1
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Gulotta A, Bucciarelli S, Roosen-Runge F, Holderer O, Schurtenberger P, Stradner A. Testing mixing rules for structural and dynamical quantities in multi-component crowded protein solutions. APL Bioeng 2024; 8:026116. [PMID: 38827499 PMCID: PMC11143939 DOI: 10.1063/5.0204201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 05/14/2024] [Indexed: 06/04/2024] Open
Abstract
Crowding effects significantly influence the phase behavior and the structural and dynamic properties of the concentrated protein mixtures present in the cytoplasm of cells or in the blood serum. This poses enormous difficulties for our theoretical understanding and our ability to predict the behavior of these systems. While the use of course grained colloid-inspired models allows us to reproduce the key physical solution properties of concentrated monodisperse solutions of individual proteins, we lack corresponding theories for complex polydisperse mixtures. Here, we test the applicability of simple mixing rules in order to predict solution properties of protein mixtures. We use binary mixtures of the well-characterized bovine eye lens proteins α and γB crystallin as model systems. Combining microrheology with static and dynamic scattering techniques and observations of the phase diagram for liquid-liquid phase separation, we show that reasonably accurate descriptions are possible for macroscopic and mesoscopic signatures, while information on the length scale of the individual protein size requires more information on cross-component interaction.
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Affiliation(s)
- Alessandro Gulotta
- Division for Physical Chemistry, Lund University, Naturvetarvägen 14, 22100 Lund, Sweden
| | - Saskia Bucciarelli
- Division for Physical Chemistry, Lund University, Naturvetarvägen 14, 22100 Lund, Sweden
| | | | - Olaf Holderer
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Garching, Germany
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2
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Peters J, Oliva R, Caliò A, Oger P, Winter R. Effects of Crowding and Cosolutes on Biomolecular Function at Extreme Environmental Conditions. Chem Rev 2023; 123:13441-13488. [PMID: 37943516 DOI: 10.1021/acs.chemrev.3c00432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2023]
Abstract
The extent of the effect of cellular crowding and cosolutes on the functioning of proteins and cells is manifold and includes the stabilization of the biomolecular systems, the excluded volume effect, and the modulation of molecular dynamics. Simultaneously, it is becoming increasingly clear how important it is to take the environment into account if we are to shed light on biological function under various external conditions. Many biosystems thrive under extreme conditions, including the deep sea and subseafloor crust, and can take advantage of some of the effects of crowding. These relationships have been studied in recent years using various biophysical techniques, including neutron and X-ray scattering, calorimetry, FTIR, UV-vis and fluorescence spectroscopies. Combining knowledge of the structure and conformational dynamics of biomolecules under extreme conditions, such as temperature, high hydrostatic pressure, and high salinity, we highlight the importance of considering all results in the context of the environment. Here we discuss crowding and cosolute effects on proteins, nucleic acids, membranes, and live cells and explain how it is possible to experimentally separate crowding-induced effects from other influences. Such findings will contribute to a better understanding of the homeoviscous adaptation of organisms and the limits of life in general.
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Affiliation(s)
- Judith Peters
- Univ. Grenoble Alpes, CNRS, LiPhy, 140 rue de la physique, 38400 St Martin d'Hères, France
- Institut Laue Langevin, 71 avenue des Martyrs, 38000 Grenoble, France
- Institut Universitaire de France, 75005 Paris, France
| | - Rosario Oliva
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, 80126 Naples, Italy
| | - Antonino Caliò
- European Synchrotron Radiation Facility, 71 avenue des Martyrs, 38000 Grenoble, France
| | - Philippe Oger
- INSA Lyon, Universite Claude Bernard Lyon1, CNRS, UMR5240, 69621 Villeurbanne, France
| | - Roland Winter
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, Dortmund, Otto-Hahn-Str. 4a, D-44227 Dortmund, Germany
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3
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Contraction of the rigor actomyosin complex drives bulk hemoglobin expulsion from hemolyzing erythrocytes. Biomech Model Mechanobiol 2022; 22:417-432. [PMID: 36357646 PMCID: PMC10097772 DOI: 10.1007/s10237-022-01654-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 10/23/2022] [Indexed: 11/12/2022]
Abstract
Erythrocyte ghost formation via hemolysis is a key event in the physiological clearance of senescent red blood cells (RBCs) in the spleen. The turnover rate of millions of RBCs per second necessitates a rapid efflux of hemoglobin (Hb) from RBCs by a not yet identified mechanism. Using high-speed video-microscopy of isolated RBCs, we show that electroporation-induced efflux of cytosolic ATP and other small solutes leads to transient cell shrinkage and echinocytosis, followed by osmotic swelling to the critical hemolytic volume. The onset of hemolysis coincided with a sudden self-propelled cell motion, accompanied by cell contraction and Hb-jet ejection. Our biomechanical model, which relates the Hb-jet-driven cell motion to the cytosolic pressure generation via elastic contraction of the RBC membrane, showed that the contributions of the bilayer and the bilayer-anchored spectrin cytoskeleton to the hemolytic cell motion are negligible. Consistent with the biomechanical analysis, our biochemical experiments, involving extracellular ATP and the myosin inhibitor blebbistatin, identify the low abundant non-muscle myosin 2A (NM2A) as the key contributor to the Hb-jet emission and fast hemolytic cell motion. Thus, our data reveal a rapid myosin-based mechanism of hemolysis, as opposed to a much slower diffusive Hb efflux.
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4
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Beck C, Grimaldo M, Lopez H, Da Vela S, Sohmen B, Zhang F, Oettel M, Barrat JL, Roosen-Runge F, Schreiber F, Seydel T. Short-Time Transport Properties of Bidisperse Suspensions of Immunoglobulins and Serum Albumins Consistent with a Colloid Physics Picture. J Phys Chem B 2022; 126:7400-7408. [PMID: 36112146 PMCID: PMC9527755 DOI: 10.1021/acs.jpcb.2c02380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
The crowded environment of biological systems such as
the interior
of living cells is occupied by macromolecules with a broad size distribution.
This situation of polydispersity might influence the dependence of
the diffusive dynamics of a given tracer macromolecule in a monodisperse
solution on its hydrodynamic size and on the volume fraction. The
resulting size dependence of diffusive transport crucially influences
the function of a living cell. Here, we investigate a simplified model
system consisting of two constituents in aqueous solution, namely,
of the proteins bovine serum albumin (BSA) and bovine polyclonal gamma-globulin
(Ig), systematically depending on the total volume fraction and ratio
of these constituents. From high-resolution quasi-elastic neutron
spectroscopy, the separate apparent short-time diffusion coefficients
for BSA and Ig in the mixture are extracted, which show substantial
deviations from the diffusion coefficients measured in monodisperse
solutions at the same total volume fraction. These deviations can
be modeled quantitatively using results from the short-time rotational
and translational diffusion in a two-component hard sphere system
with two distinct, effective hydrodynamic radii. Thus, we find that
a simple colloid picture well describes short-time diffusion in binary
mixtures as a function of the mixing ratio and the total volume fraction.
Notably, the self-diffusion of the smaller protein BSA in the mixture
is faster than the diffusion in a pure BSA solution, whereas the self-diffusion
of Ig in the mixture is slower than in the pure Ig solution.
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Affiliation(s)
- Christian Beck
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
- Institut Max von Laue─Paul Langevin (ILL), CS 20156, F-38042 Grenoble Cedex 9, France
| | - Marco Grimaldo
- Institut Max von Laue─Paul Langevin (ILL), CS 20156, F-38042 Grenoble Cedex 9, France
| | - Hender Lopez
- School of Physics and Optometric & Clinical Sciences, Technological University Dublin, D07 XT95 Grangegorman, Ireland
| | - Stefano Da Vela
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Benedikt Sohmen
- Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany
| | - Fajun Zhang
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Martin Oettel
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | | | - Felix Roosen-Runge
- Department of Biomedical Science and Biofilms-Research Center for Biointerfaces (BRCB), Malmö University, 20506 Malmö, Sweden
| | - Frank Schreiber
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Tilo Seydel
- Institut Max von Laue─Paul Langevin (ILL), CS 20156, F-38042 Grenoble Cedex 9, France
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5
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Chen D, Kuzmenko I, Ilavsky J, Pinho L, Campanella O. Structural evolution during gelation of pea and whey proteins envisaged by time-resolved ultra-small-angle x-ray scattering (USAXS). Food Hydrocoll 2022. [DOI: 10.1016/j.foodhyd.2021.107449] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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6
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Chen Y, Yan R, Zhao N. Passive and active tracer dynamics in polymer solutions with isotropic-to-nematic phase transition. Phys Chem Chem Phys 2022; 24:7415-7429. [PMID: 35266498 DOI: 10.1039/d2cp00323f] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Macromolecular crowding plays a crucial role in determining the dynamics in a living cell. We adopt Langevin dynamics simulations to investigate the anomalous diffusion dynamics of passive and active particles in a solution of polymer chains with tunable stiffness. The solution's anisotropic feature is modulated by changing both the polymer stiffness and volume fraction, where isotropic-to-nematic phase transition is involved. Our results demonstrate the significant impact of polymer flexibility on the dynamics of both passive and active probes. The distinct diffusion mechanism for an active particle is clarified by the interplay between polymer stiffness, crowdedness and activity. Polymer stiffness leads to a global inhibition effect on passive particle diffusion. The diffusion coefficient exhibits an intriguing non-monotonic variation at increasing polymer stiffness, which is due to the fact that the alignment of polymer chains is beneficial for diffusion along the nematic direction but unfavorable for that in the direction perpendicular to it. In sharp contrast, polymer stiffness plays a dominant role in facilitating active particle diffusion. Self-propulsion of the particle can utilize stiffness-induced elastic interactions more efficiently, which promotes its mobility in both directions. Meanwhile, an active particle might have a stronger ability to take advantage of the polymer alignment, contributing substantially enhanced diffusivity. In addition, the diffusion coefficient of an active particle is subject to a tendency of degeneration against varying volume fraction. This counter-intuitive behavior is due to the contrasting factors that increasing crowdedness induces a lower particle speed but a longer persistent motion time.
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Affiliation(s)
- Ying Chen
- College of Chemistry, Sichuan University, Chengdu 610064, China.
| | - Ran Yan
- College of Chemistry, Sichuan University, Chengdu 610064, China.
| | - Nanrong Zhao
- College of Chemistry, Sichuan University, Chengdu 610064, China.
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7
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Nakagawa H, Saio T, Nagao M, Inoue R, Sugiyama M, Ajito S, Tominaga T, Kawakita Y. Conformational dynamics of a multidomain protein by neutron scattering and computational analysis. Biophys J 2021; 120:3341-3354. [PMID: 34242590 PMCID: PMC8391080 DOI: 10.1016/j.bpj.2021.07.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 06/07/2021] [Accepted: 07/01/2021] [Indexed: 11/25/2022] Open
Abstract
The flexible conformations of a multidomain protein are responsible for its biological functions. Although MurD, a 47-kDa protein that consists of three domains, sequentially changes its domain conformation from an open form to a closed form through a semiclosed form in its enzymatic reaction, the domain dynamics in each conformation remains unclear. In this study, we verify the conformational dynamics of MurD in the corresponding three states (apo and ATP- and inhibitor-bound states) with a combination of small-angle x-ray and neutron scattering (SAXS and SANS), dynamic light scattering (DLS), neutron backscattering (NBS), neutron spin echo (NSE) spectroscopy, and molecular dynamics (MD) simulations. Applying principal component analysis of the MD trajectories, twisting and open-closed domain modes are identified as the major collective coordinates. The deviations of the experimental SAXS profiles from the theoretical calculations based on the known crystal structures become smaller in the ATP-bound state than in the apo state, and a further decrease is evident upon inhibitor binding. These results suggest that domain motions of the protein are suppressed step by step of each ligand binding. The DLS and NBS data yield collective and self-translational diffusion constants, respectively, and we used them to extract collective domain motions in nanometer and nanosecond scales from the NSE data. In the apo state, MurD shows both twisting and open-closed domain modes, whereas an ATP binding suppresses twisting domain motions, and a further reduction of open-closed mode is seen in the inhibitor-binding state. These observations are consistent with the structure modifications measured by the small-angle scattering as well as the MD simulations. Such changes in the domain dynamics associated with the sequential enzymatic reactions should be related to the affinity and reaction efficiency with a ligand that binds specifically to each reaction state.
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Affiliation(s)
- Hiroshi Nakagawa
- Materials Sciences Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki, Japan; 2 J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki, Japan.
| | - Tomohide Saio
- Division of Molecular Life Science, Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan
| | - Michihiro Nagao
- NIST Centre for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland; Department of Materials Science and Engineering, University of Maryland, College Park, Maryland; Department of Physics and Astronomy, University of Delaware, Newark, Delaware
| | - Rintaro Inoue
- Institute for Integrative Radiation and Nuclear Science, Kyoto University, Kumatori, Sennan-gun, Osaka, Japan
| | - Masaaki Sugiyama
- Institute for Integrative Radiation and Nuclear Science, Kyoto University, Kumatori, Sennan-gun, Osaka, Japan
| | - Satoshi Ajito
- Materials Sciences Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki, Japan
| | - Taiki Tominaga
- Neutron Science and Technology Center, CROSS, Tokai, Ibaraki, Japan
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8
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Reinhardt M, Bruce NJ, Kokh DB, Wade RC. Brownian Dynamics Simulations of Proteins in the Presence of Surfaces: Long-Range Electrostatics and Mean-Field Hydrodynamics. J Chem Theory Comput 2021; 17:3510-3524. [PMID: 33784462 DOI: 10.1021/acs.jctc.0c01312] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Simulations of macromolecular diffusion and adsorption in confined environments can offer valuable mechanistic insights into numerous biophysical processes. In order to model solutes at atomic detail on relevant time scales, Brownian dynamics simulations can be carried out with the approximation of rigid body solutes moving through a continuum solvent. This allows the precomputation of interaction potential grids for the solutes, thereby allowing the computationally efficient calculation of forces. However, hydrodynamic and long-range electrostatic interactions cannot be fully treated with grid-based approaches alone. Here, we develop a treatment of both hydrodynamic and electrostatic interactions to include the presence of surfaces by modeling grid-based and long-range interactions. We describe its application to simulate the self-association and many-molecule adsorption of the well-characterized protein hen egg-white lysozyme to mica-like and silica-like surfaces. We find that the computational model can recover a number of experimental observables of the adsorption process and provide insights into their determinants. The computational model is implemented in the Simulation of Diffusional Association (SDA) software package.
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Affiliation(s)
- Martin Reinhardt
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Schloß-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany.,Department of Theoretical and Computational Biophysics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Neil J Bruce
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Schloß-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
| | - Daria B Kokh
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Schloß-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
| | - Rebecca C Wade
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Schloß-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany.,Center for Molecular Biology (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.,Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Im Neuenheimer Feld 368, 69120 Heidelberg, Germany
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9
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Chorieva NM, Fayziev DD, Tsiferova NA, Toshtemirova GA, Khamidova OJ, Merzlyak PG, Kurbannazarova RS, Ziyaev KL, Gafurov MB, Sabirov RZ. Lytic and sublytic effects of gossypol on red blood cells and thymocytes. Clin Exp Pharmacol Physiol 2021; 48:227-237. [PMID: 33124084 DOI: 10.1111/1440-1681.13429] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 10/22/2020] [Accepted: 10/23/2020] [Indexed: 01/21/2023]
Abstract
Gossypol is a natural polyphenol presently considered as a promising biological phytochemical with a range of activities including anticancer. We examined volume regulation-dependent effects of gossypol using erythrocytes and thymic lymphocytes. Gossypol effectively lysed human red blood cells (RBC) with a half-maximal concentration of 67.4 ± 1.6 μmol/L and in a non-colloid osmotic manner. Sublytic gossypol doses of 1-10 μmol/L significantly protected RBC from osmotic hemolysis, but potentiated their sensitivity to the colloid-osmotic lysis induced by a pore-former nystatin. When added to the thymocytes suspension, gossypol caused a strong depression of the ability of cells to restore their volume under hypoosmotic stress with a half-maximal activity at 2.1 ± 0.3 μmol/L. Gossypol suppressed regulatory volume decrease under experimental conditions, when cationic permeability was controlled by gramicidin D, and volume recovery depended mainly on anionic conductance, suggesting that the polyphenol inhibits the swelling-induced anion permeability. In direct patch-clamp experiments, gossypol inhibited the volume-sensitive outwardly rectifying (VSOR) chloride channel in thymocytes and in human HCT116 and HeLa cells, possibly by a mechanism when gossypol molecule with a radius close to the size of channel pore plugs into the narrowest portion of the native VSOR chloride channel. Micromolar gossypol suppressed proliferation of thymocytes, HCT116 and HeLa cells. VSOR blockage may represent new mechanism of anticancer activity of gossypol in addition to its action as a BH3-mimetic.
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Affiliation(s)
- Nargiza M Chorieva
- Institute of Biophysics and Biochemistry, National University of Uzbekistan, Tashkent, Uzbekistan
- Termez State University, Termez, Uzbekistan
| | - Diyor D Fayziev
- Institute of Biophysics and Biochemistry, National University of Uzbekistan, Tashkent, Uzbekistan
| | - Nargiza A Tsiferova
- Institute of Biophysics and Biochemistry, National University of Uzbekistan, Tashkent, Uzbekistan
- Center for Advanced Technologies, Tashkent, Uzbekistan
| | - Gulnoza A Toshtemirova
- Institute of Biophysics and Biochemistry, National University of Uzbekistan, Tashkent, Uzbekistan
| | - Ozoda J Khamidova
- Institute of Biophysics and Biochemistry, National University of Uzbekistan, Tashkent, Uzbekistan
| | - Petr G Merzlyak
- Institute of Biophysics and Biochemistry, National University of Uzbekistan, Tashkent, Uzbekistan
| | - Ranokhon Sh Kurbannazarova
- Institute of Biophysics and Biochemistry, National University of Uzbekistan, Tashkent, Uzbekistan
- Technical Institute of the National Guard, Tashkent, Uzbekistan
| | - Khayrulla L Ziyaev
- Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan
| | - Makhmud B Gafurov
- Institute of Bioorganic Chemistry, Academy of Sciences of Uzbekistan, Tashkent, Uzbekistan
| | - Ravshan Z Sabirov
- Institute of Biophysics and Biochemistry, National University of Uzbekistan, Tashkent, Uzbekistan
- Department of Biophysics, National University of Uzbekistan, Tashkent, Uzbekistan
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10
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Roosen-Runge F, Gulotta A, Bucciarelli S, Casal-Dujat L, Garting T, Skar-Gislinge N, Obiols-Rabasa M, Farago B, Zaccarelli E, Schurtenberger P, Stradner A. Crowding in the Eye Lens: Modeling the Multisubunit Protein β-Crystallin with a Colloidal Approach. Biophys J 2020; 119:2483-2496. [PMID: 33189682 PMCID: PMC7822730 DOI: 10.1016/j.bpj.2020.10.035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 10/07/2020] [Accepted: 10/19/2020] [Indexed: 11/29/2022] Open
Abstract
We present a multiscale characterization of aqueous solutions of the bovine eye lens protein βH crystallin from dilute conditions up to dynamical arrest, combining dynamic light scattering, small-angle x-ray scattering, tracer-based microrheology, and neutron spin echo spectroscopy. We obtain a comprehensive explanation of the observed experimental signatures from a model of polydisperse hard spheres with additional weak attraction. In particular, the model predictions quantitatively describe the multiscale dynamical results from microscopic nanometer cage diffusion over mesoscopic micrometer gradient diffusion up to macroscopic viscosity. Based on a comparative discussion with results from other crystallin proteins, we suggest an interesting common pathway for dynamical arrest in all crystallin proteins, with potential implications for the understanding of crowding effects in the eye lens.
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Affiliation(s)
| | | | | | | | - Tommy Garting
- Division of Physical Chemistry, Lund University, Lund, Sweden
| | | | | | | | - Emanuela Zaccarelli
- Institute for Complex Systems, National Research Council, Uos Sapienza, Rome, Italy; Department of Physics, Sapienza Università di Roma, Rome, Italy
| | | | - Anna Stradner
- Division of Physical Chemistry, Lund University, Lund, Sweden.
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11
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Shou K, Sarter M, de Souza NR, de Campo L, Whitten AE, Kuchel PW, Garvey CJ, Stadler AM. Effect of red blood cell shape changes on haemoglobin interactions and dynamics: a neutron scattering study. ROYAL SOCIETY OPEN SCIENCE 2020; 7:201507. [PMID: 33204483 PMCID: PMC7657910 DOI: 10.1098/rsos.201507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Accepted: 09/18/2020] [Indexed: 06/11/2023]
Abstract
By using a combination of experimental neutron scattering techniques, it is possible to obtain a statistical perspective on red blood cell (RBC) shape in suspensions, and the inter-relationship with protein interactions and dynamics inside the confinement of the cell membrane. In this study, we examined the ultrastructure of RBC and protein-protein interactions of haemoglobin (Hb) in them using ultra-small-angle neutron scattering and small-angle neutron scattering (SANS). In addition, we used the neutron backscattering method to access Hb motion on the ns time scale and Å length scale. Quasi-elastic neutron scattering (QENS) experiments were performed to measure diffusive motion of Hb in RBCs and in an RBC lysate. By using QENS, we probed both internal Hb dynamics and global protein diffusion, on the accessible time scale and length scale by QENS. Shape changes of RBCs and variation of intracellular Hb concentration were induced by addition of the Na+-selective ionophore monensin and the K+-selective one, valinomycin. The experimental SANS and QENS results are discussed within the framework of crowded protein solutions, where free motion of Hb is obstructed by mutual interactions.
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Affiliation(s)
- Keyun Shou
- Jülich Centre for Neutron Science (JCNS-1) and Institute of Biological Information Processing (IBI-8: Neutron Scattering and Biological Matter), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
- Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia
| | - Mona Sarter
- Jülich Centre for Neutron Science (JCNS-1) and Institute of Biological Information Processing (IBI-8: Neutron Scattering and Biological Matter), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
- I. Physikalisches Institut (IA), AG Biophysik, RWTH Aachen, Sommerfeldstrasse 14, 52074 Aachen, Germany
| | - Nicolas R. de Souza
- Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia
| | - Liliana de Campo
- Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia
| | - Andrew E. Whitten
- Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia
| | - Philip W. Kuchel
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Christopher J. Garvey
- Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia
- Biofilm—Research Center for Biointerfaces and Biomedical Science Department, Faculty of Health and Society, Malmö University, Malmö, Sweden
- Lund Institute for Advanced Neutron and X-ray Science, Lund, Sweden
| | - Andreas M. Stadler
- Jülich Centre for Neutron Science (JCNS-1) and Institute of Biological Information Processing (IBI-8: Neutron Scattering and Biological Matter), Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
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12
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Nikfar M, Razizadeh M, Paul R, Liu Y. Multiscale modeling of hemolysis during microfiltration. MICROFLUIDICS AND NANOFLUIDICS 2020; 24:33. [PMID: 33235552 PMCID: PMC7682248 DOI: 10.1007/s10404-020-02337-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 03/28/2020] [Indexed: 05/22/2023]
Abstract
In this paper, we propose a multiscale numerical algorithm to simulate the hemolytic release of hemoglobin (Hb) from red blood cells (RBCs) flowing through sieves containing micropores with mean diameters smaller than RBCs. Analyzing the RBC damage in microfiltration is important in the sense that it can quantify the sensitivity of human erythrocytes to mechanical hemolysis while they undergo high shear rate and high deformation. Here, the numerical simulations are carried out via lattice Boltzmann method and spring connected network (SN) coupled by an immersed boundary method. To predict the RBC sublytic damage, a sub-cellular damage model derived from molecular dynamic simulations is incorporated in the cellular solver. In the proposed algorithm, the local RBC strain distribution calculated by the cellular solver is used to obtain the pore radius on the RBC membrane. Index of hemolysis (IH) is calculated by resorting to the resulting pore radius and solving a diffusion equation considering the effects of steric hinderance and increased hydrodynamic drag due to the size of the hemoglobin molecule. It should be mentioned that current computational hemolysis models usually utilize empirical fitting of the released free hemoglobin (Hb) in plasma from damaged RBCs. These empirical correlations contain ad hoc parameters that depend on specific device and operating conditions, thus cannot be used to predict hemolysis under different conditions. In contrast to the available hemolysis model, the proposed algorithm does not have any empirical parameters. Therefore, it can predict the IH in microfilter with different sieve pore sizes and filtration pressures. Also, in contrast to empirical correlations in which the Hb release is related to shear stress and exposure time without considering the physical processes, the proposed model links flow-induced deformation of the RBC membrane to membrane permeabilization and hemoglobin release. In this paper, the cellular solver is validated by simulating optical tweezers experiment, shear flow experiment as well as an experiment to measure RBC deformability in a very narrow microchannel. Moreover, the shape of a single RBC at the rupture moment is compared with corresponding experimental data. Finally, to validate the damage model, the results obtained from our parametric study on the role of filtration pressure and sieve pore size in Hb release are compared with experimental data. Numerical results are in good agreement with experimental data. Similar to the corresponding experiment, the numerical results confirm that hemolysis increases with increasing the filtration pressure and reduction in pore size on the sieve. While in experiment, the RBC pore size cannot be measured, the numerical results can quantify the RBC pore size. The numerical results show that at the sieve pore size of 2.2 μm above 25 cm Hg, RBC pore size is above 75 nm and RBCs experience rupture. More importantly, the results demonstrate that the proposed approach is independent from the operating conditions and it can estimate the hemolysis in a wide range of filtration pressure and sieve pore size with reasonable accuracy.
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Affiliation(s)
- Mehdi Nikfar
- Department of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA 18015, USA
| | - Meghdad Razizadeh
- Department of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA 18015, USA
| | - Ratul Paul
- Department of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA 18015, USA
| | - Yaling Liu
- Department of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA 18015, USA
- Department of Bioengineering, Lehigh University, Bethlehem, PA 18015, USA
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13
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Nikfar M, Razizadeh M, Zhang J, Paul R, Wu ZJ, Liu Y. Prediction of mechanical hemolysis in medical devices via a Lagrangian strain-based multiscale model. Artif Organs 2020; 44:E348-E368. [PMID: 32017130 DOI: 10.1111/aor.13663] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 12/22/2019] [Accepted: 01/31/2020] [Indexed: 01/25/2023]
Abstract
This work introduces a new Lagrangian strain-based model to predict the shear-induced hemolysis in biomedical devices. Current computational models for device-induced hemolysis usually utilize empirical fitting of the released free hemoglobin (Hb) in plasma from damaged red blood cells (RBCs). These empirical correlations contain parameters that depend on specific device and operating conditions, thus cannot be used to predict hemolysis in a general device. The proposed algorithm does not have any empirical parameters, thus can presumably be used for hemolysis prediction in various blood-wetting medical devices. In contrast to empirical correlations in which the Hb release is related to the shear stress and exposure time without considering the physical processes, the proposed model links flow-induced deformation of the RBC membrane to membrane permeabilization and Hb release. In this approach, once the steady-state numerical solution of blood flow in the device is obtained under a prescribed operating condition, sample path lines are traced from the inlet of the device to the outlet to calculate the history of the shear stress tensor. In solving the fluid flow, it is assumed that RBCs do not have any influence on the flow pattern. Along each path line, shear stress tensor will be input into a coarse-grained (CG) RBC model to calculate the RBC deformation. Then the correlations obtained from molecular dynamics (MD) simulations are applied to relate the local areal RBC deformation to the perforated area on the RBC membrane. Finally, Hb released out of transient pores is calculated over each path line via a diffusion equation considering the effects of the steric hindrance and increased hydrodynamic drag due to the size of the Hb molecule. The total index of hemolysis (IH) is calculated by integration of released Hb over all the path lines in the computational domain. Hemolysis generated in the Food and Drug Administration (FDA) nozzle and two blood pumps, that is, a CentriMag blood pump (a centrifugal pump) and HeartMate II (an axial pump), for different flow regimes including the laminar and turbulent flows are calculated via the proposed algorithm. In all the simulations, the numerical predicted IH is close to the range of experimental data. The results promisingly indicate that this multiscale approach can be used as a tool for predicting hemolysis and optimizing the hematologic design of other types of blood-wetting devices.
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Affiliation(s)
- Mehdi Nikfar
- Department of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA, USA
| | - Meghdad Razizadeh
- Department of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA, USA
| | - Jiafeng Zhang
- Department of Surgery, University of Maryland, School of Medicine, Baltimore, MD, USA
| | - Ratul Paul
- Department of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA, USA
| | - Zhongjun J Wu
- Department of Surgery, University of Maryland, School of Medicine, Baltimore, MD, USA
| | - Yaling Liu
- Department of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA, USA.,Department of Bioengineering, Lehigh University, Bethlehem, PA, USA
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14
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Blake RC, White RA. In situ absorbance measurements: a new means to study respiratory electron transfer in chemolithotrophic microorganisms. Adv Microb Physiol 2020; 76:81-127. [PMID: 32408948 DOI: 10.1016/bs.ampbs.2020.01.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Absorbance measurements on intact chemolithotrophic microorganisms that respire aerobically on soluble iron are described that used a novel integrating cavity absorption meter to eliminate the effects of light scattering on the experimental results. Steady state kinetic measurements on ferric iron production by intact cells revealed that the Michaelis Menten equation described the initial rates of product formation for at least 8 different chemolithotrophic microorganisms in 6 phyla distributed equally among the archaea and the Gram negative and Gram positive eubacteria. Cell-monitored turnover measurements during aerobic respiration on soluble iron by the same 12 intact microorganisms revealed six different patterns of iron-dependent absorbance changes, suggesting that there may be at least six different sets of prosthetic groups and biomolecules that can accomplish aerobic respiration on soluble iron. Detailed kinetic studies revealed that the 3-component iron respiratory chain of Acidithiobacillus ferrooxidans functioned as an ensemble with a single macroscopic rate constant when the iron-reduced proteins were oxidized in the presence of excess molecular oxygen. The principal member of this 3-component system was a cupredoxin called rusticyanin that was present in the periplasm of At. ferrooxidans at an approximate concentration of 350 mg/mL, an observation that provides new insights into the crowded environments in the periplasms of Gram negative eubacteria that conduct electrons across their periplasm. The ability to conduct direct spectrophotometric measurements under noninvasive physiological conditions represents a new and powerful approach to examine the rates and extents of biological events in situ without disrupting the complexity of the live cellular environment.
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Affiliation(s)
- Robert C Blake
- College of Pharmacy, Xavier University of Louisiana, New Orleans, United States
| | - Richard A White
- Department of Plant Pathology, Washington State University, Pullman, WA, United States; RAW Molecular Systems (RMS) LLC, Spokane, WA, United States; Australian Centre for Astrobiology, University of New South Wales, Sydney, NSW, Australia
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15
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Wälchli R, Ressurreição M, Vogg S, Feidl F, Angelo J, Xu X, Ghose S, Jian Li Z, Le Saoût X, Souquet J, Broly H, Morbidelli M. Understanding mAb aggregation during low pH viral inactivation and subsequent neutralization. Biotechnol Bioeng 2019; 117:687-700. [PMID: 31784982 DOI: 10.1002/bit.27237] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 10/22/2019] [Accepted: 11/22/2019] [Indexed: 12/31/2022]
Abstract
Monoclonal antibodies (mAbs) and related recombinant proteins continue to gain importance in the treatment of a great variety of diseases. Despite significant advances, their manufacturing can still present challenges owing to their molecular complexity and stringent regulations with respect to product purity, stability, safety, and so forth. In this context, protein aggregates are of particular concern due to their immunogenic potential. During manufacturing, mAbs routinely undergo acidic treatment to inactivate viral contamination, which can lead to their aggregation and thereby to product loss. To better understand the underlying mechanism so as to propose strategies to mitigate the issue, we systematically investigated the denaturation and aggregation of two mAbs at low pH as well as after neutralization. We observed that at low pH and low ionic strength, mAb surface hydrophobicity increased whereas molecular size remained constant. After neutralization of acidic mAb solutions, the fraction of monomeric mAb started to decrease accompanied by an increase on average mAb size. This indicates that electrostatic repulsion prevents denatured mAb molecules from aggregation under acidic pH and low ionic strength, whereas neutralization reduces this repulsion and coagulation initiates. Limiting denaturation at low pH by d-sorbitol addition or temperature reduction effectively improved monomer recovery after neutralization. Our findings might be used to develop innovative viral inactivation procedures during mAb manufacturing that result in higher product yields.
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Affiliation(s)
- Ruben Wälchli
- Department of Chemistry and Applied Biosciences, ETH Zurich, Institute for Chemical and Bioengineering, Zurich, Switzerland
| | - Mariana Ressurreição
- Department of Chemistry and Applied Biosciences, ETH Zurich, Institute for Chemical and Bioengineering, Zurich, Switzerland
| | - Sebastian Vogg
- Department of Chemistry and Applied Biosciences, ETH Zurich, Institute for Chemical and Bioengineering, Zurich, Switzerland
| | - Fabian Feidl
- Department of Chemistry and Applied Biosciences, ETH Zurich, Institute for Chemical and Bioengineering, Zurich, Switzerland
| | - James Angelo
- Biologics Process Development, Global Product Development and Supply, Bristol-Myers Squibb Co., Devens, Massachusetts
| | - Xuankuo Xu
- Biologics Process Development, Global Product Development and Supply, Bristol-Myers Squibb Co., Devens, Massachusetts
| | - Sanchayita Ghose
- Biologics Process Development, Global Product Development and Supply, Bristol-Myers Squibb Co., Devens, Massachusetts
| | - Zheng Jian Li
- Biologics Process Development, Global Product Development and Supply, Bristol-Myers Squibb Co., Devens, Massachusetts
| | - Xavier Le Saoût
- Biotech Process Sciences, Merck KGaA, Corsier-sur-Vevey, Vaud, Switzerland
| | - Jonathan Souquet
- Biotech Process Sciences, Merck KGaA, Corsier-sur-Vevey, Vaud, Switzerland
| | - Hervé Broly
- Biotech Process Sciences, Merck KGaA, Corsier-sur-Vevey, Vaud, Switzerland
| | - Massimo Morbidelli
- Department of Chemistry and Applied Biosciences, ETH Zurich, Institute for Chemical and Bioengineering, Zurich, Switzerland
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16
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Salvador-Castell M, Golub M, Martinez N, Ollivier J, Peters J, Oger P. The first study on the impact of osmolytes in whole cells of high temperature-adapted microorganisms. SOFT MATTER 2019; 15:8381-8391. [PMID: 31613294 DOI: 10.1039/c9sm01196j] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The hyperthermophilic piezophile, Thermococcus barophilus displays a strong stress response characterized by the accumulation of the organic osmolyte, mannosylglycerate during growth under sub-optimal pressure conditions (0.1 MPa). Taking advantage of this known effect, the impact of osmolytes in piezophiles in an otherwise identical cellular context was investigated, by comparing T. barophilus cells grown under low or optimal pressures (40 MPa). Using neutron scattering techniques, we studied the molecular dynamics of live cells of T. barophilus at different pressures and temperatures. We show that in the presence of osmolytes, cells present a higher diffusion coefficient of hydration water and an increase of bulk water motions at a high temperature. In the absence of osmolytes, the T. barophilus cellular dynamics is more responsive to high temperature and high hydrostatic pressure. These results therefore give clear evidence for a protecting effect of osmolytes on proteins.
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17
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Abstract
Diffusional motion within the crowded environment of the cell is known to be crucial to cellular function as it drives the interactions of proteins. However, the relationships between protein diffusion, shape and interaction, and the evolutionary selection mechanisms that arise as a consequence, have not been investigated. Here, we study the dynamics of triaxial ellipsoids of equivalent steric volume to proteins at different aspect ratios and volume fractions using a combination of Brownian molecular dynamics and geometric packing. In general, proteins are found to have a shape, approximately Golden in aspect ratio, that give rise to the highest critical volume fraction resisting gelation, corresponding to the fastest long-time self-diffusion in the cell. The ellipsoidal shape also directs random collisions between proteins away from sites that would promote aggregation and loss of function to more rapidly evolving nonsticky regions on the surface, and further provides a greater tolerance to mutation.
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18
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Liu Y. Short-time dynamics of proteins in solutions studied by neutron spin echo. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.07.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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19
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Abstract
AbstractThe dynamics of proteins in solution includes a variety of processes, such as backbone and side-chain fluctuations, interdomain motions, as well as global rotational and translational (i.e. center of mass) diffusion. Since protein dynamics is related to protein function and essential transport processes, a detailed mechanistic understanding and monitoring of protein dynamics in solution is highly desirable. The hierarchical character of protein dynamics requires experimental tools addressing a broad range of time- and length scales. We discuss how different techniques contribute to a comprehensive picture of protein dynamics, and focus in particular on results from neutron spectroscopy. We outline the underlying principles and review available instrumentation as well as related analysis frameworks.
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20
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von Bülow S, Siggel M, Linke M, Hummer G. Dynamic cluster formation determines viscosity and diffusion in dense protein solutions. Proc Natl Acad Sci U S A 2019; 116:9843-9852. [PMID: 31036655 PMCID: PMC6525548 DOI: 10.1073/pnas.1817564116] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We develop a detailed description of protein translational and rotational diffusion in concentrated solution on the basis of all-atom molecular dynamics simulations in explicit solvent. Our systems contain up to 540 fully flexible proteins with 3.6 million atoms. In concentrated protein solutions (100 mg/mL and higher), the proteins ubiquitin and lysozyme, as well as the protein domains third IgG-binding domain of protein G and villin headpiece, diffuse not as isolated particles, but as members of transient clusters between which they constantly exchange. A dynamic cluster model nearly quantitatively explains the increase in viscosity and the decrease in protein diffusivity with protein volume fraction, which both exceed the predictions from widely used colloid models. The Stokes-Einstein relations for translational and rotational diffusion remain valid, but the effective hydrodynamic radius grows linearly with protein volume fraction. This increase follows the observed increase in cluster size and explains the more dramatic slowdown of protein rotation compared with translation. Baxter's sticky-sphere model of colloidal suspensions captures the concentration dependence of cluster size, viscosity, and rotational and translational diffusion. The consistency between simulations and experiments for a diverse set of soluble globular proteins indicates that the cluster model applies broadly to concentrated protein solutions, with equilibrium dissociation constants for nonspecific protein-protein binding in the Kd ≈ 10-mM regime.
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Affiliation(s)
- Sören von Bülow
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Marc Siggel
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Max Linke
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany;
- Department of Physics, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
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21
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Anand R, Agrawal M, Mattaparthi VS, Swaminathan R, Santra SB. Consequences of Heterogeneous Crowding on an Enzymatic Reaction: A Residence Time Monte Carlo Approach. ACS OMEGA 2019; 4:727-736. [PMID: 31459357 PMCID: PMC6649177 DOI: 10.1021/acsomega.8b02863] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 12/26/2018] [Indexed: 05/06/2023]
Abstract
Translational diffusion of a free substrate in crowded metabolically active spaces such as cell cytoplasm or mitochondrial matrix is punctuated by collisions and nonspecific interactions with soluble/immobile macromolecules/macrostructures in a variety of shapes/sizes. It is not understood how such disruptions alter enzyme reaction kinetics in such spaces. A novel Monte Carlo (MC) technique, "residence time MC", has been developed to study the kinetics of a simple enzyme-substrate reaction in a crowded milieu using a single immobile enzyme in the midst of diffusing substrates and products. The reaction time lost while the substrate nonspecifically interacts or is transiently trapped with ambient macromolecules is quantified by introducing the residence time "tau". Tau scales with the size of crowding macromolecules but makes the knowledge of their shape redundant. The residence time thus presents a convenient parameter to realistically mimic the sticky surroundings encountered by a diffusing substrate in heterogeneously crowded physiological spaces. Results reveal that for identical substrate concentration and excluded volume, increase in tau significantly diminished enzymatic product yield and reaction rate, slowed down substrate/product diffusion, and prolonged their relaxation times. A smooth transition from the anomalous subdiffusive motion to normal diffusion at long time limits was observed irrespective of the value of tau. The predictions from the model are shown to be in qualitative agreement with in vitro experimental data revealing the rate of alkaline phosphatase-catalyzed hydrolysis of p-nitrophenyl phosphate in the midst of 40/500/2000 kDa dextrans. Our findings from the residence time MC model also attempt to rationalize previously unexplained experimental observations in crowded enzyme kinetics literature. Furthermore, major insights to emerge from this study are the reasons why free diffusion of the substrate in crowded physiological spaces is detrimental to enzyme function. It is argued that organized enzyme clusters such as "metabolon" may perhaps exist to regulate the substrate translocation in such sticky physiological spaces to maintain optimal enzyme function. In summary, this work provides key insights explaining why absence of substrate channeling can dramatically slow down enzyme reaction rate in crowded metabolically active spaces.
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Affiliation(s)
- Rajat Anand
- Department of Biosciences and Bioengineering and Department of
Physics, Indian Institute of Technology
Guwahati, Guwahati 781039, Assam, India
| | - Manish Agrawal
- Department of Biosciences and Bioengineering and Department of
Physics, Indian Institute of Technology
Guwahati, Guwahati 781039, Assam, India
| | - Venkata Satish
Kumar Mattaparthi
- Department of Biosciences and Bioengineering and Department of
Physics, Indian Institute of Technology
Guwahati, Guwahati 781039, Assam, India
| | - Rajaram Swaminathan
- Department of Biosciences and Bioengineering and Department of
Physics, Indian Institute of Technology
Guwahati, Guwahati 781039, Assam, India
- E-mail:
| | - Sitangshu Bikas Santra
- Department of Biosciences and Bioengineering and Department of
Physics, Indian Institute of Technology
Guwahati, Guwahati 781039, Assam, India
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22
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Myung JS, Roosen-Runge F, Winkler RG, Gompper G, Schurtenberger P, Stradner A. Weak Shape Anisotropy Leads to a Nonmonotonic Contribution to Crowding, Impacting Protein Dynamics under Physiologically Relevant Conditions. J Phys Chem B 2018; 122:12396-12402. [PMID: 30499666 PMCID: PMC6349356 DOI: 10.1021/acs.jpcb.8b07901] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
The effect of a nonspherical
particle shape on the dynamics in
crowded solutions presents a significant challenge for a comprehensive
understanding of interaction and structural relaxation in biological
and soft matter. We report that small deviations from a spherical
shape induce a nonmonotonic contribution to the crowding effect on
the short-time cage diffusion compared with spherical systems, using
molecular dynamics simulations with mesoscale hydrodynamics of a multiparticle
collision dynamics fluid in semidilute systems with volume fractions
smaller than 0.35. We show that the nonmonotonic effect due to anisotropy
is caused by the combination of a reduced relative mobility over the
entire concentration range and a looser and less homogeneous cage
packing of nonspherical particles. Our finding stresses that nonsphericity
induces new complexity, which cannot be accounted for in effective
sphere models, and is of great interest in applications such as formulations
as well as for the fundamental understanding of soft matter in general
and crowding effects in living cells in particular.
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Affiliation(s)
- Jin Suk Myung
- Division of Physical Chemistry, Department of Chemistry , Lund University , SE-221 00 Lund , Sweden
| | - Felix Roosen-Runge
- Division of Physical Chemistry, Department of Chemistry , Lund University , SE-221 00 Lund , Sweden
| | - Roland G Winkler
- Theoretical Soft Matter and Biophysics, Institute of Complex Systems and Institute for Advanced Simulation , Forschungszentrum Jülich , D-52425 Jülich , Germany
| | - Gerhard Gompper
- Theoretical Soft Matter and Biophysics, Institute of Complex Systems and Institute for Advanced Simulation , Forschungszentrum Jülich , D-52425 Jülich , Germany
| | - Peter Schurtenberger
- Division of Physical Chemistry, Department of Chemistry , Lund University , SE-221 00 Lund , Sweden
| | - Anna Stradner
- Division of Physical Chemistry, Department of Chemistry , Lund University , SE-221 00 Lund , Sweden
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23
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Beck C, Grimaldo M, Roosen-Runge F, Braun MK, Zhang F, Schreiber F, Seydel T. Nanosecond Tracer Diffusion as a Probe of the Solution Structure and Molecular Mobility of Protein Assemblies: The Case of Ovalbumin. J Phys Chem B 2018; 122:8343-8350. [PMID: 30106587 DOI: 10.1021/acs.jpcb.8b04349] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Protein diffusion is not only an important process ensuring biological function but can also be used as a probe to obtain information on structural properties of protein assemblies in liquid solutions. Here, we explore the oligomerization state of ovalbumin at high protein concentrations by means of its short-time self-diffusion. We employ high-resolution incoherent quasielastic neutron scattering to access the self-diffusion on nanosecond timescales, on which interparticle contacts are not altered. Our results indicate that ovalbumin in aqueous (D2O) solutions occurs in increasingly large assemblies of its monomeric subunits with rising protein concentration. It changes from nearly monomeric toward dimeric and ultimately larger than tetrameric complexes. Simultaneously, we access information on the internal molecular mobility of ovalbumin on the nanometer length scale and compare it with results obtained for bovine serum albumin, immunoglobulin, and β-lactoglobulin.
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Affiliation(s)
- Christian Beck
- Institut Max von Laue-Paul Langevin (ILL) , B.P.156, F-38042 Grenoble , France.,Institut für Angewandte Physik , Universität Tübingen , Auf der Morgenstelle 10 , 72076 Tübingen , Germany
| | - Marco Grimaldo
- Institut Max von Laue-Paul Langevin (ILL) , B.P.156, F-38042 Grenoble , France
| | - Felix Roosen-Runge
- Division of Physical Chemistry, Department of Chemistry , Lund University , Naturvetarvägen 16 , SE-22100 Lund , Sweden
| | - Michal K Braun
- Institut für Angewandte Physik , Universität Tübingen , Auf der Morgenstelle 10 , 72076 Tübingen , Germany
| | - Fajun Zhang
- Institut für Angewandte Physik , Universität Tübingen , Auf der Morgenstelle 10 , 72076 Tübingen , Germany
| | - Frank Schreiber
- Institut für Angewandte Physik , Universität Tübingen , Auf der Morgenstelle 10 , 72076 Tübingen , Germany
| | - Tilo Seydel
- Institut Max von Laue-Paul Langevin (ILL) , B.P.156, F-38042 Grenoble , France
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24
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Riest J, Nägele G, Liu Y, Wagner NJ, Godfrin PD. Short-time dynamics of lysozyme solutions with competing short-range attraction and long-range repulsion: Experiment and theory. J Chem Phys 2018; 148:065101. [DOI: 10.1063/1.5016517] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Affiliation(s)
- Jonas Riest
- Forschungszentrum Jülich GmbH, ICS-3–Soft Condensed Matter, 52428 Jülich, Germany and Jülich-Aachen Research Alliance JARA–Soft Matter, 52425 Jülich, Germany
| | - Gerhard Nägele
- Forschungszentrum Jülich GmbH, ICS-3–Soft Condensed Matter, 52428 Jülich, Germany and Jülich-Aachen Research Alliance JARA–Soft Matter, 52425 Jülich, Germany
| | - Yun Liu
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA and Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, USA
| | - Norman J. Wagner
- Center for Neutron Science, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, USA
| | - P. Douglas Godfrin
- Center for Neutron Science, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, USA
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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25
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Longeville S, Stingaciu LR. Hemoglobin diffusion and the dynamics of oxygen capture by red blood cells. Sci Rep 2017; 7:10448. [PMID: 28874711 PMCID: PMC5585185 DOI: 10.1038/s41598-017-09146-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 07/21/2017] [Indexed: 11/17/2022] Open
Abstract
Translational diffusion of macromolecules in cell is generally assumed to be anomalous due high macromolecular crowding of the milieu. Red blood cells are a special case of cells filled quasi exclusively (95% of the dry weight of the cell) with an almost spherical protein: hemoglobin. Hemoglobin diffusion has since a long time been recognized as facilitating the rate of oxygen diffusion through a solution. We address in this paper the question on how hemoglobin diffusion in the red blood cells can help the oxygen capture at the cell level and hence to improve oxygen transport. We report a measurement by neutron spin echo spectroscopy of the diffusion of hemoglobin in solutions with increasing protein concentration. We show that hemoglobin diffusion in solution can be described as Brownian motion up to physiological concentration and that hemoglobin diffusion in the red blood cells and in solutions at similar concentration are the same. Finally, using a simple model and the concentration dependence of the diffusion of the protein reported here, we show that hemoglobin concentration observed in human red blood cells ([Formula: see text]330 g.L -1) corresponds to an optimum for oxygen transport for individuals under strong activity.
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Affiliation(s)
- Stéphane Longeville
- Laboratoire Léon Brillouin, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, F-91191, Gif-sur-Yvette, France.
| | - Laura-Roxana Stingaciu
- Juelich Centre for Neutron Science, outstation at SNS, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
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26
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Fujiwara S, Chatake T, Matsuo T, Kono F, Tominaga T, Shibata K, Sato-Tomita A, Shibayama N. Ligation-Dependent Picosecond Dynamics in Human Hemoglobin As Revealed by Quasielastic Neutron Scattering. J Phys Chem B 2017; 121:8069-8077. [DOI: 10.1021/acs.jpcb.7b05182] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Satoru Fujiwara
- Quantum
Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology, 2-4 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Toshiyuki Chatake
- Research
Reactor Institute, Kyoto University, 2 Asashiro-Nishi, Kumatori, Osaka 590-0494, Japan
| | - Tatsuhito Matsuo
- Quantum
Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology, 2-4 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Fumiaki Kono
- Quantum
Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology, 2-4 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Taiki Tominaga
- Neutron
Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Kaoru Shibata
- Neutron
Science Section, J-PARC Center, 2-4 Shirakata, Tokai, Ibaraki 319-1195, Japan
| | - Ayana Sato-Tomita
- Division
of Biophysics, Department of Physiology, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan
| | - Naoya Shibayama
- Division
of Biophysics, Department of Physiology, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan
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27
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Lal J, Maccarini M, Fouquet P, Ho NT, Ho C, Makowski L. Modulation of hemoglobin dynamics by an allosteric effector. Protein Sci 2017; 26:505-514. [PMID: 27977887 PMCID: PMC5326564 DOI: 10.1002/pro.3099] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 12/03/2016] [Accepted: 12/07/2016] [Indexed: 11/24/2022]
Abstract
Hemoglobin (Hb) is an extensively studied paradigm of proteins that alter their function in response to allosteric effectors. Models of its action have been used as prototypes for structure‐function relationships in many proteins, and models for the molecular basis of its function have been deeply studied and extensively argued. Recent reports suggest that dynamics may play an important role in its function. Relatively little is known about the slow, correlated motions of hemoglobin subunits in various structural states because experimental and computational strategies for their characterization are challenging. Allosteric effectors such as inositol hexaphosphate (IHP) bind to both deoxy‐Hb and HbCO, albeit at different sites, leading to a lowered oxygen affinity. The manner in which these effectors impact oxygen binding is unclear and may involve changes in structure, dynamics or both. Here we use neutron spin echo measurements accompanied by wide‐angle X‐ray scattering to show that binding of IHP to HbCO results in an increase in the rate of coordinated motions of Hb subunits relative to one another with little if any change in large scale structure. This increase of large‐scale dynamics seems to be coupled with a decrease in the average magnitude of higher frequency modes of individual residues. These observations indicate that enhanced dynamic motions contribute to the functional changes induced by IHP and suggest that they may be responsible for the lowered oxygen affinity triggered by these effectors.
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Affiliation(s)
- Jyotsana Lal
- Biosciences Division, Argonne National Laboratory, Argonne, Illinois, 60439
| | - Marco Maccarini
- Institut Laue-Langevin, CS 20156, 38042 Grenoble Cedex 9, France
| | - Peter Fouquet
- Institut Laue-Langevin, CS 20156, 38042 Grenoble Cedex 9, France
| | - Nancy T Ho
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, 15213
| | - Chien Ho
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, 15213
| | - Lee Makowski
- Biosciences Division, Argonne National Laboratory, Argonne, Illinois, 60439.,Department of Bioengineering, Northeastern University, Boston, Massachusetts, 02115
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28
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Sohrabi S, Liu Y. A Cellular Model of Shear-Induced Hemolysis. Artif Organs 2017; 41:E80-E91. [PMID: 28044355 DOI: 10.1111/aor.12832] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 06/12/2016] [Accepted: 07/19/2016] [Indexed: 12/13/2022]
Abstract
A novel model is presented to study red blood cell (RBC) hemolysis at cellular level. Under high shear rates, pores form on RBC membranes through which hemoglobin (Hb) leaks out and increases free Hb content of plasma leading to hemolysis. By coupling lattice Boltzmann and spring connected network models through immersed boundary method, we estimate hemolysis of a single RBC under various shear rates. First, we use adaptive meshing to find local strain distribution and critical sites on RBC membranes, and then we apply underlying molecular dynamics simulations to evaluate damage. Our approach comprises three sub-models: defining criteria of pore formation, calculating pore size, and measuring Hb diffusive flux out of pores. Our damage model uses information of different scales to predict cellular level hemolysis. Results are compared with experimental studies and other models in literature. The developed cellular damage model can be used as a predictive tool for hydrodynamic and hematologic design optimization of blood-wetting medical devices.
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Affiliation(s)
| | - Yaling Liu
- Department of Mechanical Engineering & Mechanics.,Bioengineering Program, Lehigh University, Bethlehem, PA, USA
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29
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Chen J, Wang X, Kline SR, Liu Y. Size effects of solvent molecules on the phase behavior and effective interaction of colloidal systems with the bridging attraction. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:455102. [PMID: 27617866 DOI: 10.1088/0953-8984/28/45/455102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
There has been much recent research interest towards understanding the phase behavior of colloidal systems interacting with a bridging attraction, where the small solvent particles and large solute colloidal particles can be reversibly associated with each other. These systems show interesting phase behavior compared to the more widely studied depletion attraction systems. Here, we use Baxter's two-component sticky hard sphere model with a Percus-Yevick closure to solve the Ornstein-Zernike equation and study the size effect on colloidal systems with bridging attractions. The spinodal decomposition regions, percolation transition boundaries and binodal regions are systematically investigated as a function of the relative size of the small solvent and large solute particles as well as the attraction strength between the small and large particles. In the phase space determined by the concentrations of small and large particles, the spinodal and binodal regions form isolated islands. The locations and shapes of the spinodal and binodal regions sensitively depend on the relative size of the small and large particles and the attraction strength between them. The percolation region shrinks by decreasing the size ratio, while the binodal region slightly expands with the decrease of the size ratio. Our results are very important in understanding the phase behavior for a bridging attraction colloidal system, a model system that provides insight into oppositely charged colloidal systems, protein phase behavior, and colloidal gelation mechanisms.
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Affiliation(s)
- Jie Chen
- Department of Engineering Physics, Tsinghua University, Beijing, People's Republic of China. NIST Center for Neutron Research, Gaithersburg, MD 20899, USA
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30
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Burgin T, Johnson D, Chung H, Clark A, McGrath J. ULTRATHIN SILICON MEMBRANES FOR IMPROVING EXTRACORPOREAL BLOOD THERAPIES. PROCEEDINGS OF THE ... INTERNATIONAL CONFERENCE ON NANOCHANNELS, MICROCHANNELS AND MINICHANNELS. INTERNATIONAL CONFERENCE ON NANOCHANNELS, MICROCHANNELS AND MINICHANNELS 2016; 2016:V001T15A003. [PMID: 31602425 PMCID: PMC6785995 DOI: 10.1115/icnmm2016-8052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Extracorporeal blood therapies such as hemodialysis and extracorporeal membrane oxygenation supplement or replace organ function by the exchange of molecules between blood and another fluid across a semi-permeable membrane. Traditionally, these membranes are made of polymers with large surface areas and thicknesses on the scale of microns. Therapeutic gas exchange or toxin cleara nce in these devices occurs predominantly by diffusion, a process that is described by an inverse square law relating a distance to the average time a diffusing particle requires to travel that distance. As such, small changes in membrane thickness or other device dimensions can have significant effects on device performance - and large changes can cause dramatic paradigm shifts. In this work, we discuss the application of ultrathin nanoporous silicon membranes (nanomembranes) with thicknesses on the scale of tens of nanometers to diffusion-mediated medical devices. We discuss the theoretical consequences of nanomembrane medical devices for patients, analyzing several notable benefits such as reduced device size (enabling wearability, for instance) and improved clearance specificity. Special attention is paid to computational and analytical models that describe real experimental behavior, and that in doing so provide insights into the relevant parameters governing the devices.
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Affiliation(s)
- Tucker Burgin
- Department of Biomedical Engineering, University of Rochester, 252 Elmwood Ave Rochester, NY 14627
| | - Dean Johnson
- Department of Biomedical Engineering, University of Rochester, 252 Elmwood Ave Rochester, NY 14627
| | - Henry Chung
- Department of Biomedical Engineering, University of Rochester, 252 Elmwood Ave Rochester, NY 14627
| | - Alfred Clark
- Department of Mechanical Engineering, University of Rochester, 252 Elmwood Ave Rochester, NY 14627
| | - James McGrath
- Department of Biomedical Engineering, University of Rochester, 252 Elmwood Ave Rochester, NY 14627
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31
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Rothman JS, Kocsis L, Herzog E, Nusser Z, Silver RA. Physical determinants of vesicle mobility and supply at a central synapse. eLife 2016; 5. [PMID: 27542193 PMCID: PMC5025287 DOI: 10.7554/elife.15133] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 08/14/2016] [Indexed: 12/22/2022] Open
Abstract
Encoding continuous sensory variables requires sustained synaptic signalling. At several sensory synapses, rapid vesicle supply is achieved via highly mobile vesicles and specialized ribbon structures, but how this is achieved at central synapses without ribbons is unclear. Here we examine vesicle mobility at excitatory cerebellar mossy fibre synapses which sustain transmission over a broad frequency bandwidth. Fluorescent recovery after photobleaching in slices from VGLUT1Venus knock-in mice reveal 75% of VGLUT1-containing vesicles have a high mobility, comparable to that at ribbon synapses. Experimentally constrained models establish hydrodynamic interactions and vesicle collisions are major determinants of vesicle mobility in crowded presynaptic terminals. Moreover, models incorporating 3D reconstructions of vesicle clouds near active zones (AZs) predict the measured releasable pool size and replenishment rate from the reserve pool. They also show that while vesicle reloading at AZs is not diffusion-limited at the onset of release, diffusion limits vesicle reloading during sustained high-frequency signalling. DOI:http://dx.doi.org/10.7554/eLife.15133.001
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Affiliation(s)
- Jason Seth Rothman
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Laszlo Kocsis
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Etienne Herzog
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany.,Team Synapse in Cognition, Interdisciplinary Institute for Neuroscience, Université de Bordeaux, UMR 5297, F-33000, Bordeaux, France
| | - Zoltan Nusser
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Robin Angus Silver
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
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32
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Fast antibody fragment motion: flexible linkers act as entropic spring. Sci Rep 2016; 6:22148. [PMID: 27020739 PMCID: PMC4810366 DOI: 10.1038/srep22148] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 02/08/2016] [Indexed: 01/13/2023] Open
Abstract
A flexible linker region between three fragments allows antibodies to adjust their binding sites to an antigen or receptor. Using Neutron Spin Echo Spectroscopy we observed fragment motion on a timescale of 7 ns with motional amplitudes of about 1 nm relative to each other. The mechanistic complexity of the linker region can be described by a spring model with Brownian motion of the fragments in a harmonic potential. Displacements, timescale, friction and force constant of the underlying dynamics are accessed. The force constant exhibits a similar strength to an entropic spring, with friction of the fragment matching the unbound state. The observed fast motions are fluctuations in pre-existing equilibrium configurations. The Brownian motion of domains in a harmonic potential is the appropriate model to examine functional hinge motions dependent on the structural topology and highlights the role of internal forces and friction to function.
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33
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Godfrin PD, Hudson SD, Hong K, Porcar L, Falus P, Wagner NJ, Liu Y. Short-Time Glassy Dynamics in Viscous Protein Solutions with Competing Interactions. PHYSICAL REVIEW LETTERS 2015; 115:228302. [PMID: 26650319 DOI: 10.1103/physrevlett.115.228302] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Indexed: 06/05/2023]
Abstract
The glass transition of colloidal dispersions interacting with both a short-ranged attraction and long-ranged repulsion is studied using highly purified lysozyme solutions. Newtonian liquid behavior is observed at all conditions while measurements of the dynamics in the short-time limit show features typical of glassy colloidal systems at high protein concentrations. This interesting behavior is due to the competition of the attraction and repulsion that produces a heterogeneous microstructure only at intermediate range length scales. The results demonstrate that theories for the macroscopic properties of systems with competing interactions need to include intermediate range order.
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Affiliation(s)
- P Douglas Godfrin
- Center for Neutron Science, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, USA
| | - Steven D Hudson
- Polymers and Complex Fluids Group, NIST, Gaithersburg, Maryland 20899, USA
| | - Kunlun Hong
- Center for Nanophase Materials and Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Lionel Porcar
- Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156, 38042 Grenoble cedex 9, France
| | - Peter Falus
- Institut Laue-Langevin, 71 avenue des Martyrs, CS 20156, 38042 Grenoble cedex 9, France
| | - Norman J Wagner
- Center for Neutron Science, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, USA
| | - Yun Liu
- Center for Neutron Science, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, USA
- Center for Neutron Research, NIST, Gaithersburg, Maryland 20899, USA
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34
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Vascular nitric oxide: Beyond eNOS. J Pharmacol Sci 2015; 129:83-94. [PMID: 26499181 DOI: 10.1016/j.jphs.2015.09.002] [Citation(s) in RCA: 489] [Impact Index Per Article: 54.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 09/11/2015] [Accepted: 09/16/2015] [Indexed: 02/06/2023] Open
Abstract
As the first discovered gaseous signaling molecule, nitric oxide (NO) affects a number of cellular processes, including those involving vascular cells. This brief review summarizes the contribution of NO to the regulation of vascular tone and its sources in the blood vessel wall. NO regulates the degree of contraction of vascular smooth muscle cells mainly by stimulating soluble guanylyl cyclase (sGC) to produce cyclic guanosine monophosphate (cGMP), although cGMP-independent signaling [S-nitrosylation of target proteins, activation of sarco/endoplasmic reticulum calcium ATPase (SERCA) or production of cyclic inosine monophosphate (cIMP)] also can be involved. In the blood vessel wall, NO is produced mainly from l-arginine by the enzyme endothelial nitric oxide synthase (eNOS) but it can also be released non-enzymatically from S-nitrosothiols or from nitrate/nitrite. Dysfunction in the production and/or the bioavailability of NO characterizes endothelial dysfunction, which is associated with cardiovascular diseases such as hypertension and atherosclerosis.
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35
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Li TF, Painter RG, Ban B, Blake RC. The Multicenter Aerobic Iron Respiratory Chain of Acidithiobacillus ferrooxidans Functions as an Ensemble with a Single Macroscopic Rate Constant. J Biol Chem 2015; 290:18293-303. [PMID: 26041781 PMCID: PMC4513090 DOI: 10.1074/jbc.m115.657551] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 05/26/2015] [Indexed: 11/06/2022] Open
Abstract
Electron transfer reactions among three prominent colored proteins in intact cells of Acidithiobacillus ferrooxidans were monitored using an integrating cavity absorption meter that permitted the acquisition of accurate absorbance data in suspensions of cells that scattered light. The concentrations of proteins in the periplasmic space were estimated to be 350 and 25 mg/ml for rusticyanin and cytochrome c, respectively; cytochrome a was present as one molecule for every 91 nm(2) in the cytoplasmic membrane. All three proteins were rapidly reduced to the same relative extent when suspensions of live bacteria were mixed with different concentrations of ferrous ions at pH 1.5. The subsequent molecular oxygen-dependent oxidation of the multicenter respiratory chain occurred with a single macroscopic rate constant, regardless of the proteins' in vitro redox potentials or their putative positions in the aerobic iron respiratory chain. The crowded electron transport proteins in the periplasm of the organism constituted an electron conductive medium where the network of protein interactions functioned in a concerted fashion as a single ensemble with a standard reduction potential of 650 mV. The appearance of product ferric ions was correlated with the reduction levels of the periplasmic electron transfer proteins; the limiting first-order catalytic rate constant for aerobic respiration on iron was 7,400 s(-1). The ability to conduct direct spectrophotometric studies under noninvasive physiological conditions represents a new and powerful approach to examine the extent and rates of biological events in situ without disrupting the complexity of the live cellular environment.
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Affiliation(s)
- Ting-Feng Li
- From the College of Pharmacy, Xavier University of Louisiana, New Orleans, Louisiana 70125
| | - Richard G Painter
- From the College of Pharmacy, Xavier University of Louisiana, New Orleans, Louisiana 70125
| | - Bhupal Ban
- From the College of Pharmacy, Xavier University of Louisiana, New Orleans, Louisiana 70125
| | - Robert C Blake
- From the College of Pharmacy, Xavier University of Louisiana, New Orleans, Louisiana 70125
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36
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Chen J, Kline SR, Liu Y. From the depletion attraction to the bridging attraction: The effect of solvent molecules on the effective colloidal interactions. J Chem Phys 2015; 142:084904. [DOI: 10.1063/1.4913197] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Affiliation(s)
- Jie Chen
- Department of Engineering Physics, Tsinghua University, Beijing, China
- Center for Neutron Research, National Institute of Standards and Technology, Gaithursburg, Maryland 20899, USA
| | - Steven R. Kline
- Center for Neutron Research, National Institute of Standards and Technology, Gaithursburg, Maryland 20899, USA
| | - Yun Liu
- Center for Neutron Research, National Institute of Standards and Technology, Gaithursburg, Maryland 20899, USA
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, USA
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37
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Pajic-Lijakovic I. Erythrocytes under osmotic stress – modeling considerations. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 117:113-24. [DOI: 10.1016/j.pbiomolbio.2014.11.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 10/10/2014] [Accepted: 11/19/2014] [Indexed: 10/24/2022]
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38
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Grimaldo M, Roosen-Runge F, Zhang F, Seydel T, Schreiber F. Diffusion and Dynamics of γ-Globulin in Crowded Aqueous Solutions. J Phys Chem B 2014; 118:7203-9. [DOI: 10.1021/jp504135z] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Marco Grimaldo
- Institut Max von Laue − Paul Langevin (ILL), B.P.156, F-38042 Grenoble, France
- Institut
für Angewandte Physik, Universität Tübingen, Auf
der Morgenstelle 10, D-72076 Tübingen, Germany
| | - Felix Roosen-Runge
- Institut Max von Laue − Paul Langevin (ILL), B.P.156, F-38042 Grenoble, France
| | - Fajun Zhang
- Institut
für Angewandte Physik, Universität Tübingen, Auf
der Morgenstelle 10, D-72076 Tübingen, Germany
| | - Tilo Seydel
- Institut Max von Laue − Paul Langevin (ILL), B.P.156, F-38042 Grenoble, France
| | - Frank Schreiber
- Institut
für Angewandte Physik, Universität Tübingen, Auf
der Morgenstelle 10, D-72076 Tübingen, Germany
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39
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Blanco MA, Perevozchikova T, Martorana V, Manno M, Roberts CJ. Protein-protein interactions in dilute to concentrated solutions: α-chymotrypsinogen in acidic conditions. J Phys Chem B 2014; 118:5817-31. [PMID: 24810917 PMCID: PMC4051245 DOI: 10.1021/jp412301h] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Protein-protein interactions were investigated for α-chymotrypsinogen by static and dynamic light scattering (SLS and DLS, respectively), as well as small-angle neutron scattering (SANS), as a function of protein and salt concentration at acidic conditions. Net protein-protein interactions were probed via the Kirkwood-Buff integral G22 and the static structure factor S(q) from SLS and SANS data. G22 was obtained by regressing the Rayleigh ratio versus protein concentration with a local Taylor series approach, which does not require one to assume the underlying form or nature of intermolecular interactions. In addition, G22 and S(q) were further analyzed by traditional methods involving fits to effective interaction potentials. Although the fitted model parameters were not always physically realistic, the numerical values for G22 and S(q → 0) were in good agreement from SLS and SANS as a function of protein concentration. In the dilute regime, fitted G22 values agreed with those obtained via the osmotic second virial coefficient B22 and showed that electrostatic interactions are the dominant contribution for colloidal interactions in α-chymotrypsinogen solutions. However, as protein concentration increases, the strength of protein-protein interactions decreases, with a more pronounced decrease at low salt concentrations. The results are consistent with an effective "crowding" or excluded volume contribution to G22 due to the long-ranged electrostatic repulsions that are prominent even at the moderate range of protein concentrations used here (<40 g/L). These apparent crowding effects were confirmed and quantified by assessing the hydrodynamic factor H(q → 0), which is obtained by combining measurements of the collective diffusion coefficient from DLS data with measurements of S(q → 0). H(q → 0) was significantly less than that for a corresponding hard-sphere system and showed that hydrodynamic nonidealities can lead to qualitatively incorrect conclusions regarding B22, G22, and static protein-protein interactions if one uses only DLS to assess protein interactions.
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Affiliation(s)
- Marco A Blanco
- Department of Chemical and Biomolecular Engineering, University of Delaware , Newark, Delaware 19716, United States
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40
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Trovato F, Nifosì R, Di Fenza A, Tozzini V. A Minimalist Model of Protein Diffusion and Interactions: The Green Fluorescent Protein within the Cytoplasm. Macromolecules 2013. [DOI: 10.1021/ma401843h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Fabio Trovato
- Center
for Nanotechnology and Innovation @ NEST-Istituto Italiano di Tecnologia, 56127 Pisa, Italy
- Scuola Normale Superiore, Piazza
San Silvestro 12, 56127 Pisa, Italy
| | - Riccardo Nifosì
- NEST- Istituto Nanoscienze, CNR, 56127 Pisa, Italy
- Scuola Normale Superiore, Piazza
San Silvestro 12, 56127 Pisa, Italy
| | - Armida Di Fenza
- Scuola Normale Superiore, Piazza
San Silvestro 12, 56127 Pisa, Italy
- MGU, MRC Harwell, Harwell
Science and Innovation Campus, Oxfordshire OX11 0RD, U.K
| | - Valentina Tozzini
- NEST- Istituto Nanoscienze, CNR, 56127 Pisa, Italy
- Scuola Normale Superiore, Piazza
San Silvestro 12, 56127 Pisa, Italy
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41
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Grünberger A, Lai PK, Blanco MA, Roberts CJ. Coarse-grained modeling of protein second osmotic virial coefficients: sterics and short-ranged attractions. J Phys Chem B 2013; 117:763-70. [PMID: 23245189 DOI: 10.1021/jp308234j] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A series of coarse-grained models, with different levels of structural resolution, were tested to calculate the steric contributions to protein osmotic second virial coefficients (B(22,S)) for proteins ranging from small single-domain molecules to large multidomain molecules, using the recently developed Mayer sampling method. B(22,S) was compared for different levels of coarse-graining: four-beads-per-amino-acid (4bAA), one-bead-per-amino-acid (1bAA), one-sphere-per-domain (1sD), and one-sphere-per-protein (1sP). Values for the 1bAA and 4bAA models were quantitatively indistinguishable for both spherical and nonspherical proteins, and the agreement with values from all-atom models improved with increasing protein size, making the CG approach attractive for large proteins of biotechnological interest. Interestingly, in the absence of detailed structural information, the hydrodynamic radius (R(h)) along with a simple 1sP approximation provided reasonably accurate values for B(22,S) for both globular and highly asymmetric protein structures, while other 1sP approximations gave poorer agreement; this helps to justify the currently empirical practice of estimating B(22,S) from R(h) for large proteins such as antibodies. The results also indicate that either 1bAA or 4bAA CG models may be good starting points for incorporating short-range attractions. Comparison of gD-crystallin B(22) values including both sterics and short-range attractions shows that 1bAA and 4bAA models give equivalent results when properly scaled to account for differences in the number of surface beads in the two CG descriptions. This provides a basis for future work that will also incorporate long-ranged electrostatic attractions and repulsions.
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Affiliation(s)
- Alexander Grünberger
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, USA
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42
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Abstract
In the densely filled biological cells often subdiffusion is observed, where the average squared displacement increases slower than linear with the length of the observation interval. One reason for such subdiffusive behavior is attractive interactions between the diffusing particles that lead to temporary complex formation. Here, we show that such transient binding is not an average state of the particles but that intervals of free diffusion alternate with slower displacement when bound to neighboring particles. The observed macroscopic behavior is then the weighted average of these two contributions. Interestingly, even at very high concentrations, the unbound fraction still exhibits essentially normal diffusion.
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Affiliation(s)
- Tihamér Geyer
- Zentrum für Bioinformatik, Universität des Saarlandes, D-66041 Saarbrücken, Germany.
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43
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Qin S, Cai L, Zhou HX. A method for computing association rate constants of atomistically represented proteins under macromolecular crowding. Phys Biol 2012. [PMID: 23197255 DOI: 10.1088/1478-3975/9/6/066008] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
In cellular environments, two protein molecules on their way to form a specific complex encounter many bystander macromolecules. The latter molecules, or crowders, affect both the energetics of the interaction between the test molecules and the dynamics of their relative motion. In earlier work (Zhou and Szabo 1991 J. Chem. Phys. 95 5948-52), it has been shown that, in modeling the association kinetics of the test molecules, the presence of crowders can be accounted for by their energetic and dynamic effects. The recent development of the transient-complex theory for protein association in dilute solutions makes it possible to easily incorporate the energetic and dynamic effects of crowders. The transient complex refers to a late on-pathway intermediate, in which the two protein molecules have near-native relative separation and orientation, but have yet to form the many short-range specific interactions of the native complex. The transient-complex theory predicts the association rate constant as k(a) = k(a0)exp(-ΔG*(el)/k(B)T), where k(a0) is the 'basal' rate constant for reaching the transient complex by unbiased diffusion, and the Boltzmann factors captures the influence of long-range electrostatic interactions between the protein molecules. Crowders slow down the diffusion, therefore reducing the basal rate constant (to k(ac0)), and induce an effective interaction energy ΔG(c). We show that the latter interaction energy for atomistic proteins in the presence of spherical crowders is 'long'-ranged, allowing the association rate constant under crowding to be computed as k(ac) = k(ac0)exp[-(ΔG*(el) + ΔG*(c))/k(B)T]. Applications demonstrate that this computational method allows for realistic modeling of protein association kinetics under crowding.
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Affiliation(s)
- Sanbo Qin
- Department of Physics and Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
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Mereghetti P, Wade RC. Atomic detail brownian dynamics simulations of concentrated protein solutions with a mean field treatment of hydrodynamic interactions. J Phys Chem B 2012; 116:8523-33. [PMID: 22594708 DOI: 10.1021/jp212532h] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
High macromolecular concentrations are a distinguishing feature of living organisms. Understanding how the high concentration of solutes affects the dynamic properties of biological macromolecules is fundamental for the comprehension of biological processes in living systems. In this paper, we describe the implementation of mean field models of translational and rotational hydrodynamic interactions into an atomically detailed many-protein brownian dynamics simulation method. Concentrated solutions (30-40% volume fraction) of myoglobin, hemoglobin A, and sickle cell hemoglobin S were simulated, and static structure factors, oligomer formation, and translational and rotational self-diffusion coefficients were computed. Good agreement of computed properties with available experimental data was obtained. The results show the importance of both solvent mediated interactions and weak protein-protein interactions for accurately describing the dynamics and the association properties of concentrated protein solutions. Specifically, they show a qualitative difference in the translational and rotational dynamics of the systems studied. Although the translational diffusion coefficient is controlled by macromolecular shape and hydrodynamic interactions, the rotational diffusion coefficient is affected by macromolecular shape, direct intermolecular interactions, and both translational and rotational hydrodynamic interactions.
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Affiliation(s)
- Paolo Mereghetti
- Heidelberg Institute for Theoretical Studies (HITS) gGmbH, Schloß-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany.
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Wang SC, Mirarefi P, Faraone A, Lee CT. Light-controlled protein dynamics observed with neutron spin echo measurements. Biochemistry 2011; 50:8150-62. [PMID: 21809812 DOI: 10.1021/bi200206z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A photoresponsive surfactant has been used as a means to control protein structure and dynamics with light illumination. This cationic azobenzene surfactant, azoTAB, which undergoes a reversible photoisomerization upon exposure to the appropriate wavelength of light, adopts a relatively hydrophobic, trans structure under visible light illumination and a relatively hydrophilic cis structure under UV light illumination. Small-angle neutron scattering (SANS) and neutron spin echo (NSE) spectroscopy were used to measure the tertiary structure and internal dynamics of lysozyme in the presence of the photosurfactant, respectively. The SANS-based in vitro structures indicate that under visible light the photosurfactant induces partial unfolding that principally occurs away from the active site near the hinge region connecting the α and β domains. Upon UV exposure, however, the protein refolds to a nativelike structure. At the same time, enhanced internal dynamics of lysozyme were detected with the surfactant in the trans form through NSE measurements of the Q-dependent effective diffusion coefficient (D(eff)) of the protein. In contrast, the D(eff) values of lysozyme in the presence of cis azoTAB largely agree with the rigid-body calculation as well as those measured for pure lysozyme, suggesting that the native protein is dormant on the nanosecond time and nanometer length scales. Lysozyme internal motions were modeled by assuming a protein of two (α and β domains) or three (α and β domains and the hinge region) domains connects by either soft linkers or rigid, freely rotating bonds. Protein dynamics were also tracked with Fourier transform infrared spectroscopy through hydrogen-deuterium exchange kinetics, which further demonstrated enhanced protein flexibility induced by the trans form of the surfactant relative to the native protein. Ensemble-averaged intramolecular fluorescent resonance energy transfer measurements similarly demonstrated the enhanced dynamics of lysozyme with the trans form of the photosurfactant. Previous results have shown a significant increase in protein activity in the presence of azoTAB in the trans conformation. Combined, these results provide insight into a unique light-based method of controlling protein structure, dynamics, and function and strongly support the relevance of large domain motions for the activity of proteins.
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Affiliation(s)
- Shao-Chun Wang
- Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-1211, USA
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Abstract
Macromolecular crowding in biological media is an essential factor for cellular function. The interplay of intermolecular interactions at multiple time and length scales governs a fine-tuned system of reaction and transport processes, including particularly protein diffusion as a limiting or driving factor. Using quasielastic neutron backscattering, we probe the protein self-diffusion in crowded aqueous solutions of bovine serum albumin on nanosecond time and nanometer length scales employing the same protein as crowding agent. The measured diffusion coefficient D(ϕ) strongly decreases with increasing protein volume fraction ϕ explored within 7% ≤ ϕ ≤ 30%. With an ellipsoidal protein model and an analytical framework involving colloid diffusion theory, we separate the rotational D(r)(ϕ) and translational D(t)(ϕ) contributions to D(ϕ). The resulting D(t)(ϕ) is described by short-time self-diffusion of effective spheres. Protein self-diffusion at biological volume fractions is found to be slowed down to 20% of the dilute limit solely due to hydrodynamic interactions.
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Tokuyama M, Moriki T, Kimura Y. Self-diffusion of biomolecules in solution. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 83:051402. [PMID: 21728529 DOI: 10.1103/physreve.83.051402] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Indexed: 05/31/2023]
Abstract
A simple soft-core model potential is proposed to discuss the self-diffusion of biomolecules in solution. Extensive Brownian-dynamics simulations are performed to obtain the long-time self-diffusion coefficient. Then the simulation results are compared with the experimental data from a unified point of view recently obtained for suspensions of hard spheres. Thus, it is shown that the proposed potential can qualitatively well describe the experimental data.
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Affiliation(s)
- Michio Tokuyama
- World Premier International Research Center, Advanced Institute for Materials Research and Institute of Fluid Science, Tohoku University, Sendai, Japan
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The DFPase from Loligo vulgaris in sugar surfactant-based bicontinuous microemulsions: structure, dynamics, and enzyme activity. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2011; 40:761-74. [DOI: 10.1007/s00249-011-0689-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Revised: 02/11/2011] [Accepted: 02/17/2011] [Indexed: 11/25/2022]
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Membrane lysis by gramicidin S visualized in red blood cells and giant vesicles. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:2033-9. [DOI: 10.1016/j.bbamem.2010.07.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2010] [Revised: 06/15/2010] [Accepted: 07/05/2010] [Indexed: 12/27/2022]
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50
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Experimental analysis of Hb oxy–deoxy transition in single optically stretched red blood cells. Phys Med 2010; 26:233-9. [DOI: 10.1016/j.ejmp.2010.02.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Revised: 01/16/2010] [Accepted: 02/01/2010] [Indexed: 11/20/2022] Open
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