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Duderija B, González-Orive A, Ebbert C, Neßlinger V, Keller A, Grundmeier G. Electrode Potential-Dependent Studies of Protein Adsorption on Ti 6Al 4V Alloy. Molecules 2023; 28:5109. [PMID: 37446771 DOI: 10.3390/molecules28135109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 06/23/2023] [Accepted: 06/26/2023] [Indexed: 07/15/2023] Open
Abstract
This article presents the potential-dependent adsorption of two proteins, bovine serum albumin (BSA) and lysozyme (LYZ), on Ti6Al4V alloy at pH 7.4 and 37 °C. The adsorption process was studied on an electropolished alloy under cathodic and anodic overpotentials, compared to the open circuit potential (OCP). To analyze the adsorption process, various complementary interface analytical techniques were employed, including PM-IRRAS (polarization-modulation infrared reflection-absorption spectroscopy), AFM (atomic force microscopy), XPS (X-ray photoelectron spectroscopy), and E-QCM (electrochemical quartz crystal microbalance) measurements. The polarization experiments were conducted within a potential range where charging of the electric double layer dominates, and Faradaic currents can be disregarded. The findings highlight the significant influence of the interfacial charge distribution on the adsorption of BSA and LYZ onto the alloy surface. Furthermore, electrochemical analysis of the protein layers formed under applied overpotentials demonstrated improved corrosion protection properties. These studies provide valuable insights into protein adsorption on titanium alloys under physiological conditions, characterized by varying potentials of the passive alloy.
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Affiliation(s)
- Belma Duderija
- Technical and Macromolecular Chemistry, Paderborn University, Warburger Str. 100, 33098 Paderborn, Germany
| | - Alejandro González-Orive
- Department of Chemistry, Materials and Nanotechnology Institute, University of La Laguna, Avda, Astrofisico Francisco Sánchez s/n, 38206 San Cristóbal de La Laguna, Spain
| | - Christoph Ebbert
- Technical and Macromolecular Chemistry, Paderborn University, Warburger Str. 100, 33098 Paderborn, Germany
| | - Vanessa Neßlinger
- Technical and Macromolecular Chemistry, Paderborn University, Warburger Str. 100, 33098 Paderborn, Germany
| | - Adrian Keller
- Technical and Macromolecular Chemistry, Paderborn University, Warburger Str. 100, 33098 Paderborn, Germany
| | - Guido Grundmeier
- Technical and Macromolecular Chemistry, Paderborn University, Warburger Str. 100, 33098 Paderborn, Germany
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2
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Continuous background correction of refractive index signal to improve monoclonal antibody concentration monitoring during UF/DF and SPTFF operations. Bioprocess Biosyst Eng 2022; 45:647-657. [PMID: 34989873 DOI: 10.1007/s00449-021-02683-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 12/12/2021] [Indexed: 11/02/2022]
Abstract
Inline refractive index (RI) has the potential for monitoring protein concentration during final bulk concentration. While useful for monitoring and controlling product concentration, RI is sensitive to the respective background buffer being used for processing. This raises concerns around variations in buffer preparations, and during diafiltration where the buffer background is a mixture of different buffers during exchange. This study evaluated whether the use of a RI probe in the permeate line could facilitate continuous background subtraction (dual RI) and improve concentration monitoring during ultrafiltration/diafiltration and single pass TFF concentration for IgG1 and IgG4 antibodies. The proposed dual RI strategy yielded reductions in % error compared to the use of a single refractive index estimate from the retentate line (6.18% vs 8.63% for IgG4 and 2.65% vs 8.85% for IgG1) during traditional ultrafiltration/diafiltration. The improvement in IgG estimates were best during diafiltration where the continuous background subtraction of the permeate RI-enabled continuous monitoring of antibody material without knowledge of what the background buffer was compared to the use of a single RI estimate (6.47% vs 10.79% for IgG4 and 3.29% vs 19.59% for IgG1). In contrast minimal improvement to accuracy was obtained when using SPTFF as a concentration step. The ability to monitor product concentration changes via the proposed dual RI approach removes the need for complex calibrations, minimal worry about changing buffer backgrounds during diafiltration, and could enable better process control during product concentration in the cGMP manufacture of biologics.
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3
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Bender MF, Li Y, Ivleva VB, Gowetski DB, Paula Lei Q. Protein and glycan molecular weight determination of highly glycosylated HIV-1 envelope trimers by HPSEC-MALS. Vaccine 2021; 39:3650-3654. [PMID: 34053790 PMCID: PMC11106716 DOI: 10.1016/j.vaccine.2021.05.048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 05/15/2021] [Accepted: 05/18/2021] [Indexed: 10/21/2022]
Abstract
High Performance Size-Exclusion Chromatography coupled with Multi-Angle Light Scattering detection (HPSEC-MALS) is an important tool to provide a reliable molecular weight measurement for a large complex biomolecule. A recent HIV-1 soluble envelope trimer vaccine candidate, BG505 DS-SOSIP.664, is among the most glycosylated proteins to enter a clinical trial to date, and determination of its protein and glycan molecular weight is one of the key attributes in pre-clinical characterization. However, protein and glycans possess disparate dndcvalues making molecular weight measurement inaccurate in conventional SEC-MALS. To overcome these challenges, a simple mathematically guided experiment was explored, and a composite dndcvalue was established by utilizing protein and glycan mass contributions for the HIV-1 envelope trimer. This establishment was further verified by an orthogonal mass spectrometry analysis. This innovative, simple, and quick analytical approach can be applied broadly to measuring the molecular weight of various composite molecular structures, such as complex glycoconjugates.
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Affiliation(s)
- Michael F Bender
- Vaccine Production Program Laboratory, Vaccine Research Center, National Institute of Allergy and Infectious Disease, United States
| | - Yile Li
- Vaccine Production Program Laboratory, Vaccine Research Center, National Institute of Allergy and Infectious Disease, United States
| | - Vera B Ivleva
- Vaccine Production Program Laboratory, Vaccine Research Center, National Institute of Allergy and Infectious Disease, United States
| | - Daniel B Gowetski
- Vaccine Production Program Laboratory, Vaccine Research Center, National Institute of Allergy and Infectious Disease, United States
| | - Q Paula Lei
- Vaccine Production Program Laboratory, Vaccine Research Center, National Institute of Allergy and Infectious Disease, United States.
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4
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Holloway L, Roche A, Marzouk S, Uddin S, Ke P, Ekizoglou S, Curtis R. Determination of Protein-Protein Interactions at High Co-Solvent Concentrations Using Static and Dynamic Light Scattering. J Pharm Sci 2020; 109:2699-2709. [DOI: 10.1016/j.xphs.2020.05.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 04/07/2020] [Accepted: 05/18/2020] [Indexed: 01/21/2023]
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5
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Janc T, Lukšič M, Vlachy V, Rigaud B, Rollet AL, Korb JP, Mériguet G, Malikova N. Ion-specificity and surface water dynamics in protein solutions. Phys Chem Chem Phys 2018; 20:30340-30350. [PMID: 30488933 PMCID: PMC6318450 DOI: 10.1039/c8cp06061d] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Ion-specific effects at the protein surface are investigated here in light of the changes they infer to surface water dynamics, as observed by 1H NMR relaxation (at 20 MHz). Two well-known proteins, hen egg-white lysozyme (LZM) and bovine serum albumin (BSA), show qualitatively opposite trends in the transverse relaxation rate, R2(1H), along a series of different monovalent salt anions in the solution. Presence of salt ions increases R2(1H) in the case of lysozyme and diminishes it in the case of BSA. The effect magnifies for larger and more polarizable ions. The same contrasting effect between the two proteins is observed for protein-solvent proton exchange. This hints at subtle effects ion-binding might have on the accessibility of water surface sites on the protein. We suggest that the combination of the density of surface charge residues and surface roughness, at the atomic scale, dictates the response to the presence of salt ions and is proper to each protein. Further, a dramatic increase in R2(1H) is found to correlate closely with the formation of protein aggregates. The same ordering of salts in their ability to aggregate lysozyme, as seen previously by cloud point measurements, is reproduced here by R2(1H). 1H NMR relaxation data is supplemented by 35Cl and 14N NMR relaxation for selected salt ions to probe the ion-binding itself.
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Affiliation(s)
- Tadeja Janc
- University of Ljubljana, Faculty of Chemistry and Chemical Technology, Večna pot 113, SI-1000 Ljubljana, Slovenia
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6
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Wu W, Zhang R, McClements DJ, Chefetz B, Polubesova T, Xing B. Transformation and Speciation Analysis of Silver Nanoparticles of Dietary Supplement in Simulated Human Gastrointestinal Tract. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:8792-8800. [PMID: 29969018 DOI: 10.1021/acs.est.8b01393] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Knowledge of the physicochemical properties of ingestible silver nanoparticles (AgNPs) in the human gastrointestinal tract (GIT) is essential for assessing their bioavailability, bioactivity, and potential health risks. The gastrointestinal fate of AgNPs and silver ions from a commercial dietary supplement was therefore investigated using a simulated human GIT. In the mouth, no dissolution or aggregation of AgNPs occurred, which was attributed to the neutral pH and the formation of biomolecular corona, while the silver ions formed complexes with biomolecules (Ag-biomolecule). In the stomach, aggregation of AgNPs did not occur, but extensive dissolution was observed due to the low pH and the presence of Cl-. In the fed state (after meal), 72% AgNPs (by mass) dissolved, with 74% silver ions forming Ag-biomolecule and 26% forming AgCl. In the fasted state (before meal), 76% AgNPs dissolved, with 82% silver ions forming Ag-biomolecule and 18% forming AgCl. A biomolecular corona around AgNPs, comprised of mucin with multiple sulfhydryl groups, inhibited aggregation and dissolution of AgNPs. In the small intestine, no further dissolution or aggregation of AgNPs occurred, while the silver ions existed only as Ag-biomolecule. These results provide useful information for assessing the bioavailability of ingestible AgNPs and their subsequently potential health risks, and for the safe design and utilization of AgNPs in biomedical applications.
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Affiliation(s)
- Wenhao Wu
- Stockbridge School of Agriculture , University of Massachusetts , Amherst , Massachusetts 01003 , United States
| | - Ruojie Zhang
- Department of Food Science , University of Massachusetts , Amherst , Massachusetts 01003 , United States
| | - David Julian McClements
- Department of Food Science , University of Massachusetts , Amherst , Massachusetts 01003 , United States
| | - Benny Chefetz
- Department of Soil and Water Sciences , Hebrew University of Jerusalem , Rehovot 76100 , Israel
| | - Tamara Polubesova
- Department of Soil and Water Sciences , Hebrew University of Jerusalem , Rehovot 76100 , Israel
| | - Baoshan Xing
- Stockbridge School of Agriculture , University of Massachusetts , Amherst , Massachusetts 01003 , United States
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7
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Chen C, Hou X, Si J. Protein analysis by Mach-Zehnder interferometers with a hybrid plasmonic waveguide with nano-slots. OPTICS EXPRESS 2017; 25:31294-31308. [PMID: 29245806 DOI: 10.1364/oe.25.031294] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 11/17/2017] [Indexed: 06/07/2023]
Abstract
Optical biosensing devices for the affinity analysis of molecular binding events could offer significant advantages over current analytical methods. However, most of those excited with a single optical mode are "blind" to the conformational change of bound molecules. We succeeded in designing Mach-Zehnder interferometers (MZI) with a hybrid plasmonic (HP) waveguide with nano-slots. By addressing the structure with dual polarizations, the optogeometrical properties (density and thickness) of protein layers have been determined without ambiguity. Differences in the hybrid mode dispersion between the transverse electric (TE) and transverse magnetic (TM) modes separately allow the determination of the thickness and the density at all stages during the molecular interaction. Moreover, nano-slots can be equated with an effective optical capacitance resulting in strong field confinement and low propagation loss. A proof of concept is conducted by analyzing the conformational change of HepV, a recombinant fragment of collagen V, during complicated molecular interaction. Instead of wavelength interrogation, a cost-effective method with output intensity variation at particular wavelengths due to "resonance phenomena" was employed to monitor the biological event.
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8
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Levdikov VM, Blagova E, Young VL, Belitsky BR, Lebedev A, Sonenshein AL, Wilkinson AJ. Structure of the Branched-chain Amino Acid and GTP-sensing Global Regulator, CodY, from Bacillus subtilis. J Biol Chem 2016; 292:2714-2728. [PMID: 28011634 PMCID: PMC5314169 DOI: 10.1074/jbc.m116.754309] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 12/23/2016] [Indexed: 01/02/2023] Open
Abstract
CodY is a branched-chain amino acid (BCAA) and GTP sensor and a global regulator of transcription in low G + C Gram-positive bacteria. It controls the expression of over 100 genes and operons, principally by repressing during growth genes whose products are required for adaptations to nutrient limitation. However, the mechanism by which BCAA binding regulates transcriptional changes is not clear. It is known that CodY consists of a GAF (cGMP-stimulated phosphodiesterases, adenylate cyclases, FhlA) domain that binds BCAAs and a winged helix-turn-helix (wHTH) domain that binds to DNA, but the way in which these domains interact and the structural basis of the BCAA dependence of this interaction are unknown. To gain new insights, we determined the crystal structure of unliganded CodY from Bacillus subtilis revealing a 10-turn α-helix linking otherwise discrete GAF and wHTH domains. The structure of CodY in complex with isoleucine revealed a reorganized GAF domain. In both complexes CodY was tetrameric. Size exclusion chromatography with multiangle laser light scattering (SEC-MALLS) experiments showed that CodY is a dimer at concentrations found in bacterial cells. Comparison of structures of dimers of unliganded CodY and CodY-Ile derived from the tetramers showed a splaying of the wHTH domains when Ile was bound; splaying is likely to account for the increased affinity of Ile-bound CodY for DNA. Electrophoretic mobility shift and SEC-MALLS analyses of CodY binding to 19-36-bp operator fragments are consistent with isoleucine-dependent binding of two CodY dimers per duplex. The implications of these observations for effector control of CodY activity are discussed.
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Affiliation(s)
- Vladimir M Levdikov
- From the Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, United Kingdom
| | - Elena Blagova
- From the Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, United Kingdom
| | - Vicki L Young
- From the Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, United Kingdom
| | - Boris R Belitsky
- the Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, and
| | - Andrey Lebedev
- the STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - Abraham L Sonenshein
- the Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, and
| | - Anthony J Wilkinson
- From the Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, United Kingdom,
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9
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Theoretical approximations and experimental extinction coefficients of biopharmaceuticals. Anal Bioanal Chem 2015; 408:1523-30. [DOI: 10.1007/s00216-015-9261-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 12/02/2015] [Accepted: 12/08/2015] [Indexed: 01/25/2023]
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10
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Zangle TA, Teitell MA. Live-cell mass profiling: an emerging approach in quantitative biophysics. Nat Methods 2014; 11:1221-8. [PMID: 25423019 PMCID: PMC4319180 DOI: 10.1038/nmeth.3175] [Citation(s) in RCA: 150] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 07/22/2014] [Indexed: 12/16/2022]
Abstract
Cell mass, volume and growth rate are tightly controlled biophysical parameters in cellular development and homeostasis, and pathological cell growth defines cancer in metazoans. The first measurements of cell mass were made in the 1950s, but only recently have advances in computer science and microfabrication spurred the rapid development of precision mass-quantifying approaches. Here we discuss available techniques for quantifying the mass of single live cells with an emphasis on relative features, capabilities and drawbacks for different applications.
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Affiliation(s)
- Thomas A Zangle
- Department of Bioengineering, University of California, Los Angeles (UCLA), Los Angeles, California, USA
| | - Michael A Teitell
- 1] Department of Bioengineering, University of California, Los Angeles (UCLA), Los Angeles, California, USA. [2] Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA. [3] California NanoSystems Institute, UCLA, Los Angeles, California, USA. [4] Broad Stem Cell Research Center, UCLA, Los Angeles, California, USA. [5] Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, California, USA. [6] Molecular Biology Institute, UCLA, Los Angeles, California, USA
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11
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Miercke LJW, Robbins RA, Stroud RM. Tetra detector analysis of membrane proteins. ACTA ACUST UNITED AC 2014; 77:29.10.1-29.10.30. [PMID: 25081744 DOI: 10.1002/0471140864.ps2910s77] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Well-characterized membrane protein detergent complexes (PDC) that are pure, homogenous, and stable, with minimized excess detergent micelles, are essential for functional assays and crystallization studies. Procedural steps to measure the mass, size, shape, homogeneity, and molecular composition of PDCs and their host detergent micelles using size-exclusion chromatography (SEC) with a Viscotek Tetra Detector Array (TDA; absorbance, refractive index, light scattering, and viscosity detectors) are presented in this unit. The value of starting with a quality PDC sample, the precision and accuracy of the results, and the use of a digital benchtop refractometer are emphasized. An alternate and simplified purification and characterization approach using SEC with dual absorbance and refractive index detectors to optimize detergent and lipid concentration while measuring the PDC homogeneity is also described. Applications relative to purification and characterization goals are illustrated as well.
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Affiliation(s)
- Larry J W Miercke
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California
| | - Rebecca A Robbins
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California
| | - Robert M Stroud
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California
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12
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Wu B, Liu G, Zhang G, Craig VSJ. Stiff chains inhibit and flexible chains promote protein adsorption to polyelectrolyte multilayers. SOFT MATTER 2014; 10:3806-3816. [PMID: 24718871 DOI: 10.1039/c4sm00413b] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We tested the hypothesis that the level of protein adsorption onto polyelectrolyte multilayers (PEMs) is influenced by the chain stiffness of the polymers forming the multilayer. The implication being that by altering the chain stiffness, PEMs can be formed that promote or inhibit protein adsorption. Protein adsorption to PEMs consisting of flexible and semi-flexible polyelectrolytes was investigated. The flexible polyelectrolytes were poly(sodium 4-styrene sulfonate) (PSS) and poly(diallyldimethylammonium chloride) (PDDA) and the semi-flexible polyelectrolytes were sulfated chitosan (SC) and cationic guar gum (CGG). Polyelectrolytes were used in pairs to produce four types of polyelectrolyte multilayer films. Moreover, each of these films could be terminated with either of the polyelectrolytes resulting in protein adsorption being studied on 8 systems. Protein adsorption was investigated by optical reflectometry and quartz crystal microbalance with dissipation using bovine serum albumin as the test protein. We found that when a pair of semi-flexible polyelectrolytes was used very little protein adsorption took place, irrespective of which polyelectrolyte was used to terminate the film. When the film was formed by flexible polyelectrolytes, significant protein adsorption took place and the degree of adsorption depended strongly on which polyelectrolyte was used to terminate the film. We explain these observations by considering the conformation of the polyelectrolyte in the outermost region of the film and relate this to the flexibility of the polyelectrolyte chains employed to produce the polyelectrolyte multilayer.
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Affiliation(s)
- Bo Wu
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, 230026, P. R. China.
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13
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Benavidez TE, Garcia CD. Potential-assisted adsorption of bovine serum albumin onto optically transparent carbon electrodes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:14154-14162. [PMID: 24156567 PMCID: PMC3867293 DOI: 10.1021/la4029657] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
This article describes the effect of the applied potential on the adsorption of bovine serum albumin (BSA) to optically transparent carbon electrodes (OTCE). To decouple the effect of the applied potential from the high affinity of the protein for the bare surface, the surface of the OTCE was initially saturated with a layer of BSA. Experiments described in the article show that potential values higher than +500 mV induced a secondary adsorption process (not observed at open-circuit potential), yielding significant changes in the thickness (and adsorbed amount) of the BSA layer obtained. Although the process showed a significant dependence on the experimental conditions selected, the application of higher potentials, selection of pH values around the isoelectric point (IEP) of the protein, high concentrations of protein, and low ionic strengths yielded faster kinetics and the accumulation of larger amounts of protein on the substrate. These experiments, obtained around the IEP of the protein, contrast with the traditional hypothesis that enhanced electrostatic interactions between the polarized substrate and the (oppositely charged) protein are solely responsible for the enhanced adsorption. These results suggest that the potential applied to the electrode is able to polarize the adsorbed layer and induce dipole-dipole interactions between the adsorbed and the incoming protein. This mechanism could be responsible for the potential-dependent oversaturation of the surface and could bolster to the development of surfaces with enhanced catalytic activity and implants with improved biocompatibility.
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Affiliation(s)
| | - Carlos D. Garcia
- To whom correspondence should be addressed. One UTSA Circle, San Antonio, TX 78249, USA. Ph: (210) 458-5774, Fax: (210) 458-7428,
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14
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Soon ASC, Smith MH, Herman ES, Lyon LA, Barker TH. Development of self-assembling mixed protein micelles with temperature-modulated avidities. Adv Healthc Mater 2013; 2:1045-55. [PMID: 23441099 DOI: 10.1002/adhm.201200330] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Indexed: 11/07/2022]
Abstract
Elastin-like polypeptides (ELPs) are polypentapeptides that undergo hydrophobic collapse and aggregation above a specific transition temperature, Tt . ELP diblocks sharing a common "core" block (I60) but varying "outer" blocks (A80, P40) were designed, where Tt,I < Tt,A < Tt,P . The formation of ∼55 nm diameter mixed micelles from these ELP diblocks was verified using dynamic light scattering (DLS), multiangle light scattering (MALS) and fluorescence resonance energy transfer (FRET). To confer affinity to the blood circulating protein fibrinogen, a fibrinogen-binding tetrapeptide sequence (GPRP) was fused to A80-I60, while P40-I60 was fused to a non-binding control (GPSP). The self-assembling, peptide-displaying, mixed micelles exhibit temperature-modulated avidities for immobilized and soluble fibrinogen at 32 °C and 42 °C. In this initial proof-of-concept design, the engineered mixed micelles were shown to disengage fibrinogen at elevated temperatures. The modular nature of this system can be used for developing in vivo depot systems that will only be triggered to release in situ upon specific stimuli.
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Affiliation(s)
- Allyson S C Soon
- Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
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15
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Mehta CM, White ET, Litster JD. Correlation of second virial coefficient with solubility for proteins in salt solutions. Biotechnol Prog 2011; 28:163-70. [PMID: 22002946 DOI: 10.1002/btpr.724] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 08/30/2011] [Indexed: 11/08/2022]
Abstract
In this work, osmotic second virial coefficients (B(22)) were determined and correlated with the measured solubilities for the proteins, α-amylase, ovalbumin, and lysozyme. The B(22) values and solubilities were determined in similar solution conditions using two salts, sodium chloride and ammonium sulfate in an acidic pH range. An overall decrease in the solubility of the proteins (salting out) was observed at high concentrations of ammonium sulfate and sodium chloride solutions. However, for α-amylase, salting-in behavior was also observed in low concentration sodium chloride solutions. In ammonium sulfate solutions, the B(22) are small and close to zero below 2.4 M. As the ammonium sulfate concentrations were further increased, B(22) values decreased for all systems studied. The effect of sodium chloride on B(22) varies with concentration, solution pH, and the type of protein studied. Theoretical models show a reasonable fit to the experimental derived data of B(22) and solubility. B(22) is also directly proportional to the logarithm of the solubility values for individual proteins in salt solutions, so the log-linear empirical models developed in this work can also be used to rapidly predict solubility and B(22) values for given protein-salt systems.
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Affiliation(s)
- Chirag M Mehta
- School of Chemical Engineering, The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia.
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16
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Zhao H, Brown PH, Schuck P. On the distribution of protein refractive index increments. Biophys J 2011; 100:2309-17. [PMID: 21539801 DOI: 10.1016/j.bpj.2011.03.004] [Citation(s) in RCA: 312] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Revised: 03/04/2011] [Accepted: 03/14/2011] [Indexed: 11/25/2022] Open
Abstract
The protein refractive index increment, dn/dc, is an important parameter underlying the concentration determination and the biophysical characterization of proteins and protein complexes in many techniques. In this study, we examine the widely used assumption that most proteins have dn/dc values in a very narrow range, and reappraise the prediction of dn/dc of unmodified proteins based on their amino acid composition. Applying this approach in large scale to the entire set of known and predicted human proteins, we obtain, for the first time, to our knowledge, an estimate of the full distribution of protein dn/dc values. The distribution is close to Gaussian with a mean of 0.190 ml/g (for unmodified proteins at 589 nm) and a standard deviation of 0.003 ml/g. However, small proteins <10 kDa exhibit a larger spread, and almost 3000 proteins have values deviating by more than two standard deviations from the mean. Due to the widespread availability of protein sequences and the potential for outliers, the compositional prediction should be convenient and provide greater accuracy than an average consensus value for all proteins. We discuss how this approach should be particularly valuable for certain protein classes where a high dn/dc is coincidental to structural features, or may be functionally relevant such as in proteins of the eye.
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Affiliation(s)
- Huaying Zhao
- Dynamics of Macromolecular Assembly Section, Laboratory of Cellular Imaging and Macromolecular Biophysics, National Institutes of Health, Bethesda, Maryland, USA
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Colledge VL, Fogg MJ, Levdikov VM, Leech A, Dodson EJ, Wilkinson AJ. Structure and organisation of SinR, the master regulator of biofilm formation in Bacillus subtilis. J Mol Biol 2011; 411:597-613. [PMID: 21708175 PMCID: PMC3163267 DOI: 10.1016/j.jmb.2011.06.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Revised: 05/27/2011] [Accepted: 06/01/2011] [Indexed: 11/25/2022]
Abstract
sinR encodes a tetrameric repressor of genes required for biofilm formation in Bacillus subtilis. sinI, which is transcribed under Spo0A control, encodes a dimeric protein that binds to SinR to form a SinR-SinI heterodimer in which the DNA-binding functions of SinR are abrogated and repression of biofilm genes is relieved. The heterodimer-forming surface comprises residues conserved between SinR and SinI. Each forms a pair of α-helices that hook together to form an intermolecular four-helix bundle. Here, we are interested in the assembly of the SinR tetramer and its binding to DNA. Size-exclusion chromatography with multi-angle laser light scattering and crystallographic analysis reveal that a DNA-binding fragment of SinR (residues 1-69) is a monomer, while a SinI-binding fragment (residues 74-111) is a tetramer arranged as a dimer of dimers. The SinR(74-111) chain forms two α-helices with the organisation of the dimer similar to that observed in the SinR-SinI complex. The tetramer is formed through interactions of residues at the C-termini of the four chains. A model of the intact SinR tetramer in which the DNA binding domains surround the tetramerisation core was built. Fluorescence anisotropy and surface plasmon resonance experiments showed that SinR binds to an oligonucleotide duplex, 5'-TTTGTTCTCTAAAGAGAACTTA-3', containing a pair of SinR consensus sequences in inverted orientation with a K(d) of 300 nM. The implications of these data for promoter binding and the curious quaternary structural transitions of SinR upon binding to (i) SinI and (ii) the SinR-like protein SlrR, which "repurposes" SinR as a repressor of autolysin and motility genes, are discussed.
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Affiliation(s)
- Vicki L Colledge
- Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5YW, UK
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18
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Dreier B, Mikheeva G, Belousova N, Parizek P, Boczek E, Jelesarov I, Forrer P, Plückthun A, Krasnykh V. Her2-specific multivalent adapters confer designed tropism to adenovirus for gene targeting. J Mol Biol 2010; 405:410-26. [PMID: 21056576 DOI: 10.1016/j.jmb.2010.10.040] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Revised: 10/20/2010] [Accepted: 10/22/2010] [Indexed: 11/18/2022]
Abstract
Adenoviruses (Ads) hold great promise as gene vectors for diagnostic or therapeutic applications. The native tropism of Ads must be modified to achieve disease site-specific gene delivery by Ad vectors and this should be done in a programmable way and with technology that can realistically be scaled up. To this end, we applied the technologies of designed ankyrin repeat proteins (DARPins) and ribosome display to develop a DARPin that binds the knob domain of the Ad fiber protein with low nanomolar affinity (K(D) 1.35 nM) and fused this protein with a DARPin specific for Her2, an established cell-surface biomarker of human cancers. The stability of the complex formed by this bispecific targeting adapter and the Ad virion resulted in insufficient gene transfer and was subsequently improved by increasing the valency of adapter-virus binding. In particular, we designed adapters that chelated the knob in a bivalent or trivalent fashion and showed that the efficacy of gene transfer by the adapter-Ad complex increased with the functional affinity of these molecules. This enabled efficient transduction at low stoichiometric adapter-to-fiber ratios. We confirmed the Her2 specificity of this transduction and its dependence on the Her2-binding DARPin component of the adapters. Even the adapter molecules with four fused DARPins could be produced and purified from Escherichia coli at very high levels. In principle, DARPins can be generated against any target and this adapter approach provides a versatile strategy for developing a broad range of disease-specific gene vectors.
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Affiliation(s)
- Birgit Dreier
- Department of Biochemistry, University of Zurich, Winterthurerstr. 190, CH-8057 Zurich, Switzerland
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19
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Yohannes G, Wiedmer SK, Elomaa M, Jussila M, Aseyev V, Riekkola ML. Thermal aggregation of bovine serum albumin studied by asymmetrical flow field-flow fractionation. Anal Chim Acta 2010; 675:191-8. [DOI: 10.1016/j.aca.2010.07.016] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 07/11/2010] [Accepted: 07/12/2010] [Indexed: 11/27/2022]
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20
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Sharma DK, King D, Oma P, Merchant C. Micro-flow imaging: flow microscopy applied to sub-visible particulate analysis in protein formulations. AAPS JOURNAL 2010; 12:455-64. [PMID: 20517661 PMCID: PMC2895433 DOI: 10.1208/s12248-010-9205-1] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Accepted: 05/12/2010] [Indexed: 11/30/2022]
Abstract
The need to monitor, measure, and control sub-visible proteinaceous particulates in biopharmaceutical formulations has been emphasized in recent publications and commentaries. Some of these particulates can be highly transparent, fragile, and unstable. In addition, for much of the size range of concern, no practical measurement method with adequate sensitivity and repeatability has been available. A complication in measuring protein particulates in many formulations is the simultaneous presence of other particle types such as silicone micro-droplets, air bubbles, and extrinsic contaminants. The need has therefore been identified for new analytical methods which can accurately measure and characterize sub-visible particulates in formulations. Micro-flow imaging has been shown to provide high sensitivity in detecting and imaging transparent protein particles and a unique capability to independently analyze such populations even when other particle types are present.
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Affiliation(s)
- Deepak K Sharma
- Brightwell Technologies Inc, 115 Terence Matthews Crescent, Ottawa, Ontario K2M2B2, Canada.
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21
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Mora MF, Nejadnik MR, Baylon-Cardiel JL, Giacomelli CE, Garcia CD. Determination of a setup correction function to obtain adsorption kinetic data at stagnation point flow conditions. J Colloid Interface Sci 2010; 346:208-15. [PMID: 20219204 PMCID: PMC2892644 DOI: 10.1016/j.jcis.2010.02.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 02/03/2010] [Accepted: 02/11/2010] [Indexed: 10/19/2022]
Abstract
This paper is the first report on the characterization of the hydrodynamic conditions in a flow cell designed to study adsorption processes by spectroscopic ellipsometry. The resulting cell enables combining the advantages of in situ spectroscopic ellipsometry with stagnation point flow conditions. An additional advantage is that the proposed cell features a fixed position of the "inlet tube" with respect to the substrate, thus facilitating the alignment of multiple substrates. Theoretical calculations were performed by computational fluid dynamics and compared with experimental data (adsorption kinetics) obtained for the adsorption of polyethylene glycol to silica under a variety of experimental conditions. Additionally, a simple methodology to correct experimental data for errors associated with the size of the measured spot and for variations of mass transfer in the vicinity of the stagnation point is herein introduced. The proposed correction method would allow researchers to reasonably estimate the adsorption kinetics at the stagnation point and quantitatively compare their results, even when using different experimental setups. The applicability of the proposed correction function was verified by evaluating the kinetics of protein adsorption under different experimental conditions.
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Affiliation(s)
- Maria F. Mora
- Department of Chemistry, The University of Texas at San Antonio
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22
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Montalvo BL, Pacheco Y, Sosa BA, Vélez D, Sánchez G, Griebenow K. Formation of spherical protein nanoparticles without impacting protein integrity. NANOTECHNOLOGY 2008; 19:465103. [PMID: 21836234 DOI: 10.1088/0957-4484/19/46/465103] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Protein formulation at the nanoscale is challenging because of protein susceptibility to chemical and physical degradation during processing. Herein, we present a straightforward method to prepare spherical protein nanoparticles by co-lyophilizing five structurally different enzymes (horseradish peroxidase, carbonic anhydrase, lysozyme, subtilisin Carlsberg and α-chymotrypsin) with methyl-β-cyclodextrin followed by suspension of the powders in ethyl acetate. The size distribution was narrow and varied from 88 ± 14 to 148 ± 16 nm as determined by dynamic light scattering. Scanning and transmission electron micrographs confirmed the size and spherical morphology of the protein nanoparticles. Residual activities for all enzymes tested were 100% upon dissolving the nanoparticles in buffer and no insoluble aggregates were formed.
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Affiliation(s)
- Brenda L Montalvo
- Department of Chemistry, University of Puerto Rico, Río Piedras Campus, PO Box 23346, San Juan, PR 00931-3346, USA
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23
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Static light scattering to characterize membrane proteins in detergent solution. Methods 2008; 46:73-82. [DOI: 10.1016/j.ymeth.2008.06.012] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Revised: 06/02/2008] [Accepted: 06/05/2008] [Indexed: 11/22/2022] Open
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24
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Arakawa T, Wen J. Size-exclusion chromatography with on-line light scattering. ACTA ACUST UNITED AC 2008; Chapter 20:Unit 20.6. [PMID: 18429161 DOI: 10.1002/0471140864.ps2006s25] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This unit describes the use of size-exclusion chromatography with on-line light scattering, UV absorbance, and refractive index detectors (SEC-LS/UV/RI) to determine: (a) the molecular weight of simple proteins containing no carbohydrates, (b) the molecular weight of glycoproteins, and (c), most importantly, the molecular weight and stoichiometry of protein-protein complexes or protein-carbohydrate complexes. Multiangle light scattering is also discussed.
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Affiliation(s)
- T Arakawa
- Alliance Protein Laboratories, Inc., Thousand Oaks, California, USA
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25
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Ricard-Blum S, Peel LL, Ruggiero F, Freeman NJ. Dual polarization interferometry characterization of carbohydrate–protein interactions. Anal Biochem 2006; 352:252-9. [PMID: 16545768 DOI: 10.1016/j.ab.2006.02.011] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Revised: 02/03/2006] [Accepted: 02/07/2006] [Indexed: 10/25/2022]
Abstract
Dual polarization interferometry (DPI) is an analytical technique that allows the simultaneous determination of thickness, density, and mass of a biological layer on a sensing waveguide surface in real time. The technique was applied to the analysis of carbohydrate-protein interactions. The selected system involved a 12-kDa recombinant fragment of collagen V (HepV) and heparin, a complex polysaccharide. Here we report on the analysis of thickness, density, and mass of surface structures obtained during the binding of HepV to heparin, which is a useful model compound for the sulfated, protein-binding regions of heparan sulfate. This system, which was initially studied for its biological relevance, displayed anomalous behavior in kinetic studies using surface plasmon resonance (SPR) assays that has been attributed to putative conformational changes. It was this putative conformational change that prompted us to investigate the binding using an alternative analytical approach. While using DPI to monitor binding events, a streptavidin layer (surface coverage 2.105 ng mm(-2)) was bound to the sensor surface (92% coverage), which captured 0.105 ng mm(-2) of biotinylated heparin (a stoichiometric ratio of 1:6 heparin-streptavidin). The heparin inserted into the streptavidin layer but was still found to be capable of binding 0.154 ng mm(-2) of HepV, which was also observed to insert into the streptavidin layer. This allowed the reliable calculation of the stoichiometric ratio for the HepV-heparin complex ( approximately 1.7:1.0), which has proved to be difficult to evaluate by SPR assays. Furthermore, real-time analysis of the heparin-HepV interaction by DPI suggested that there was some surface loss (probably of streptavidin) while the binding was occurring rather than the putative conformational change that has been suggested on the basis of kinetic data alone. This gives further insight into the binding mechanism of HepV to heparin.
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Affiliation(s)
- Sylvie Ricard-Blum
- Institut de Biologie et Chimie des Protéines, UMR 5086 CNRS-UCBL, 7 passage du Vercors 69367, Lyon cedex 07, France
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26
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Lillis B, Manning M, Berney H, Hurley E, Mathewson A, Sheehan MM. Dual polarisation interferometry characterisation of DNA immobilisation and hybridisation detection on a silanised support. Biosens Bioelectron 2006; 21:1459-67. [PMID: 16112566 DOI: 10.1016/j.bios.2005.06.009] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Revised: 06/16/2005] [Accepted: 06/17/2005] [Indexed: 11/21/2022]
Abstract
Dual polarisation interferometry is an analytical technique that allows the simultaneous determination of thickness, density and mass of a biological layer on a sensing waveguide surface in real time. We evaluated, for the first time, the ability of this technique to characterise the covalent immobilisation of single stranded probe DNA and the selective detection of target DNA hybridisation on a silanised support. Two immobilisation strategies have been evaluated: direct attachment of the probe molecule and a more complex chemistry employing a 1,2 homobifunctional crosslinker molecule. With this technique we demonstrate it was possible to determine probe orientation and measure probe coverage at different stages of the immobilisation process in real time and in a single experiment. In addition, by measuring simultaneously changes in thickness and density of the probe layer upon hybridisation of target DNA, it was possible to directly elucidate the impact that probe mobility had on hybridisation efficiency. Direct covalent attachment of an amine modified 19 mer resulted in a thickness change of 0.68 nm that was consistent with multipoint attachment of the probe molecule to the surface. Blocking with BSA formed a dense layer of protein molecules that absorbed between the probe molecules on the surface. The observed hybridisation efficiency to target DNA was approximately 35%. No further significant reorientation of the probe molecule occurred upon hybridisation. The initial thickness of the probe layer upon attachment to the crosslinker molecule was 0.5 nm. Significant reorientation of the probe molecule surface normal occurred upon hybridisation to target DNA. This indicated that the probe molecule had greater mobility to hybridise to target DNA. The observed hybridisation efficiency for target DNA was approximately 85%. The results show that a probe molecule attached to the surface via a crosslinker group is better able to hybridise to target DNA due to its greater mobility.
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Affiliation(s)
- B Lillis
- Tyndall Institute, Lee Maltings, Prospect Row, Cork, Ireland
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27
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Lu JR, Swann MJ, Peel LL, Freeman NJ. Lysozyme adsorption studies at the silica/water interface using dual polarization interferometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:1827-1832. [PMID: 15801450 DOI: 10.1021/la0360299] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Lysozyme adsorption at the silica/water interface has been studied using a new analytical technique called dual polarization interferometry. This laboratory-based technique allows the build up or removal of molecular layers adsorbing or reacting on a lightly doped silicon dioxide (silica) surface to be measured in terms of thickness and refractive index changes with time. Lysozyme adsorption was studied at a range of concentrations from 0.03 to 4.0 g dm(-3) and at both pH 4 and pH 7. Adsorbed layers ranging from 14 to 43 +/- 1 A in thickness and 0.21 to 2.36 +/- 0.05 mg m(-2) in mass coverage were observed at pH 4 with increasing lysozyme concentration, indicating a strong deformation of the monolayer over the low concentration range and the formation of an almost complete sideways-on bilayer toward the high concentration of 4 g dm(-3). At pH 7, the thickness of adsorbed layers varied from 16 to 54 +/- 1 A with significantly higher surface coverage (0.74 to 3.29 +/- 0.05 mg m(-2)), again indicating structural deformation during the initial monolayer formation, followed by a gradual transition to bilayer adsorption over the high concentration end. The pH recycling performed at a fixed lysozyme concentration of 1.0 g dm(-3) indicated a broadly reversible adsorption regardless of whether the pH was cycled from pH 7 to pH 4 and back again or vice versa. These observations are in good agreement with earlier studies undertaken using neutron reflection although the fine details of molecular orientations in the layers differ subtly.
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Affiliation(s)
- Jian R Lu
- Biological Physics Group, Department of Physics, UMIST, PO Box 88, Manchester M60 1QD, United Kingdom
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28
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Abstract
In the light scattering technique, glycosylation gives rise to excess light scattering for glycoproteins. Assuming additivity of refractive index and using an appropriate refractive index increment for carbohydrate, one can determine the degree of glycosylation from the excess light scattering. Here we have used size-exclusion chromatography in combination with online light scattering, UV absorbance, and refractive index. The results show that the technique accurately determines the carbohydrate content of recombinant stem cell factor.
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Affiliation(s)
- T Arakawa
- Alliance Protein Laboratories, 3957 Corte Cancion, Thousand Oaks, California 91360, USA.
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