1
|
Shu P, You G, Li W, Chen Y, Chu Z, Qin D, Wang Y, Zhou H, Zhao L. Cefmetazole sodium as an allosteric effector that regulates the oxygen supply efficiency of adult hemoglobin. J Biomol Struct Dyn 2024; 42:7442-7456. [PMID: 37555593 DOI: 10.1080/07391102.2023.2245043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 07/17/2023] [Indexed: 08/10/2023]
Abstract
Allosteric effectors play an important role in regulating the oxygen supply efficiency of hemoglobin for blood storage and disease treatment. However, allosteric effectors that are approved by the US FDA are limited. In this study, cefmetazole sodium (CS) was found to bind adult hemoglobin (HbA) from FDA library (1338 compounds) using surface plasmon resonance imaging high-throughput screening. Using surface plasmon resonance (SPR), the interaction between CS and HbA was verified. The oxygen dissociation curve of HbA after CS interaction showed a significant increase in P50 and theoretical oxygen-release capacity. Acid-base sensitivity (SI) exhibited a decreasing trend, although not significantly different. An oxygen dissociation assay indicated that CS accelerated HbA deoxygenation. Microfluidic modulated spectroscopy showed that CS changed the ratio of the alpha-helix to the beta-sheet of HbA. Molecular docking suggested CS bound to HbA's β-chains via hydrogen bonds, with key amino acids being N282, K225, H545, K625, K675, and V544.The results of molecular dynamics simulations (MD) revealed a stable orientation of the HbA-CS complex. CS did not significantly affect the P50 of bovine hemoglobin, possibly due to the lack of Valβ1 and Hisβ2, indicating that these were the crucial amino acids involved in HbA's oxygen affinity. Competition between the 2,3-Diphosphoglycerate (2,3-DPG) and CS in the HbA interaction was also determined by SPR, molecular docking and MD. In summary, CS could interact with HbA and regulate the oxygen supply efficiency via forming stable hydrogen bonds with the β-chains of HbA, and showed competition with 2,3-DPG.Communicated by Ramaswamy H. Sarma.
Collapse
Affiliation(s)
- Peilin Shu
- Institute of Health Service and Transfusion Medicine, Academy of Military Medical Sciences, Academy of Military Science of the Chinese People's Liberation Army, Beijing, P.R. C
| | - Guoxing You
- Institute of Health Service and Transfusion Medicine, Academy of Military Medical Sciences, Academy of Military Science of the Chinese People's Liberation Army, Beijing, P.R. C
| | - Weidan Li
- Institute of Health Service and Transfusion Medicine, Academy of Military Medical Sciences, Academy of Military Science of the Chinese People's Liberation Army, Beijing, P.R. C
| | - Yuzhi Chen
- Institute of Health Service and Transfusion Medicine, Academy of Military Medical Sciences, Academy of Military Science of the Chinese People's Liberation Army, Beijing, P.R. C
| | - Zongtang Chu
- Institute of Health Service and Transfusion Medicine, Academy of Military Medical Sciences, Academy of Military Science of the Chinese People's Liberation Army, Beijing, P.R. C
| | - Dong Qin
- Institute of Health Service and Transfusion Medicine, Academy of Military Medical Sciences, Academy of Military Science of the Chinese People's Liberation Army, Beijing, P.R. C
| | - Ying Wang
- Institute of Health Service and Transfusion Medicine, Academy of Military Medical Sciences, Academy of Military Science of the Chinese People's Liberation Army, Beijing, P.R. C
| | - Hong Zhou
- Institute of Health Service and Transfusion Medicine, Academy of Military Medical Sciences, Academy of Military Science of the Chinese People's Liberation Army, Beijing, P.R. C
| | - Lian Zhao
- Institute of Health Service and Transfusion Medicine, Academy of Military Medical Sciences, Academy of Military Science of the Chinese People's Liberation Army, Beijing, P.R. C
| |
Collapse
|
2
|
Aydin S, Salehi SM, Töpfer K, Meuwly M. SCN as a local probe of protein structural dynamics. J Chem Phys 2024; 161:055101. [PMID: 39092954 DOI: 10.1063/5.0216657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 07/03/2024] [Indexed: 08/04/2024] Open
Abstract
The dynamics of lysozyme is probed by attaching -SCN to all alanine residues. The one-dimensional infrared spectra exhibit frequency shifts in the position of the maximum absorption of 4 cm-1, which is consistent with experiments in different solvents and indicates moderately strong interactions of the vibrational probe with its environment. Isotopic substitution 12C → 13C leads to a redshift by -47 cm-1, which agrees quantitatively with experiments for CN-substituted copper complexes in solution. The low-frequency, far-infrared part of the protein spectra contains label-specific information in the difference spectra when compared with the wild type protein. Depending on the position of the labels, local structural changes are observed. For example, introducing the -SCN label at Ala129 leads to breaking of the α-helical structure with concomitant change in the far-infrared spectrum. Finally, changes in the local hydration of SCN-labeled alanine residues as a function of time can be related to the reorientation of the label. It is concluded that -SCN is potentially useful for probing protein dynamics, both in the high-frequency part (CN-stretch) and in the far-infrared part of the spectrum.
Collapse
Affiliation(s)
- Sena Aydin
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Seyedeh Maryam Salehi
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Kai Töpfer
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
| |
Collapse
|
3
|
Zhang HQ, Sun C, Xu N, Liu W. The current landscape of the antimicrobial peptide melittin and its therapeutic potential. Front Immunol 2024; 15:1326033. [PMID: 38318188 PMCID: PMC10838977 DOI: 10.3389/fimmu.2024.1326033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Accepted: 01/03/2024] [Indexed: 02/07/2024] Open
Abstract
Melittin, a main component of bee venom, is a cationic amphiphilic peptide with a linear α-helix structure. It has been reported that melittin can exert pharmacological effects, such as antitumor, antiviral and anti-inflammatory effects in vitro and in vivo. In particular, melittin may be beneficial for the treatment of diseases for which no specific clinical therapeutic agents exist. Melittin can effectively enhance the therapeutic properties of some first-line drugs. Elucidating the mechanism underlying melittin-mediated biological function can provide valuable insights for the application of melittin in disease intervention. However, in melittin, the positively charged amino acids enables it to directly punching holes in cell membranes. The hemolysis in red cells and the cytotoxicity triggered by melittin limit its applications. Melittin-based nanomodification, immuno-conjugation, structural regulation and gene technology strategies have been demonstrated to enhance the specificity, reduce the cytotoxicity and limit the off-target cytolysis of melittin, which suggests the potential of melittin to be used clinically. This article summarizes research progress on antiviral, antitumor and anti-inflammatory properties of melittin, and discusses the strategies of melittin-modification for its future potential clinical applications in preventing drug resistance, enhancing the selectivity to target cells and alleviating cytotoxic effects to normal cells.
Collapse
Affiliation(s)
- Hai-Qian Zhang
- Changchun Veterinary Research Institute, Chinese Academy of Agricultural Science, Changchun, Jilin, China
| | - Chengbiao Sun
- Changchun Veterinary Research Institute, Chinese Academy of Agricultural Science, Changchun, Jilin, China
| | - Na Xu
- Academic Affairs Office, Jilin Medical University, Jilin, Jilin, China
| | - Wensen Liu
- Changchun Veterinary Research Institute, Chinese Academy of Agricultural Science, Changchun, Jilin, China
| |
Collapse
|
4
|
Shin S, Willard AP. Quantifying the Molecular Polarization Response of Liquid Water Interfaces at Heterogeneously Charged Surfaces. J Chem Theory Comput 2023; 19:1843-1852. [PMID: 36866865 DOI: 10.1021/acs.jctc.2c01256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
The hydration shells of proteins mediate interactions, such as small molecule binding, that are vital to their biological function or in some cases their dysfunction. However, even when the structure of a protein is known, the properties of its hydration environment cannot be easily predicted due to the complex interplay between protein surface heterogeneity and the collective structure of water's hydrogen bonding network. This manuscript presents a theoretical study of the influence of surface charge heterogeneity on the polarization response of the liquid water interface. We focus our attention on classical point charge models of water, where the polarization response is limited to molecular reorientation. We introduce a new computational method for analyzing simulation data that is capable of quantifying water's collective polarization response and determining the effective surface charge distribution of hydrated surfaces over atomistic length scales. To illustrate the utility of this method, we present the results of molecular dynamics simulations of liquid water in contact with a heterogeneous model surface and the CheY protein.
Collapse
Affiliation(s)
- Sucheol Shin
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.,Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Adam P Willard
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| |
Collapse
|
5
|
Turan HT, Meuwly M. Local Hydration Control and Functional Implications Through S-Nitrosylation of Proteins: Kirsten Rat Sarcoma Virus (K-RAS) and Hemoglobin (Hb). J Phys Chem B 2023; 127:1526-1539. [PMID: 36757772 DOI: 10.1021/acs.jpcb.2c07371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
S-nitrosylation, the covalent addition of NO to the thiol side chain of cysteine, is an important post-transitional modification (PTM) that can affect the function of proteins. As such, PTMs extend and diversify protein function and thus characterizing consequences of PTM at a molecular level is of great interest. Although PTMs can be detected through various direct/indirect methods, they lack the capability to investigate the modifications with molecular detail. In the present work local and global structural dynamics, their correlation, the hydration structure, and the infrared spectroscopy for WT and S-nitrosylated Kirsten rat sarcoma virus (K-RAS) and hemoglobin (Hb) are characterized from molecular dynamics simulations. It is found that attaching NO to Cys118 in K-RAS rigidifies the protein in the Switch-I region which has functional implications, whereas for Hb, nitrosylation at Cys93 at the β1 chain increases the flexibility of secondary structural motives for Hb in its T0 and R4 conformational substates. Solvent water access decreased by 40% after nitrosylation in K-RAS, similar to Hb for which, however, local hydration of the R4SNO state is yet lower than for T0SNO. Finally, S-nitrosylation leads to detectable peaks for the NO stretch frequency, but the congested IR spectral region will make experimental detection of these bands difficult. Overall, S-nitrosylation in these two proteins is found to influence hydration, protein flexibility, and conformational dynamics which are all eventually involved in protein regulation and function at a molecular level.
Collapse
Affiliation(s)
- Haydar Taylan Turan
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
| | - Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
| |
Collapse
|
6
|
Salehi SM, Pezzella M, Willard A, Meuwly M, Karplus M. Water dynamics around T 0 vs R 4 of hemoglobin from local hydrophobicity analysis. J Chem Phys 2023; 158:025101. [PMID: 36641390 DOI: 10.1063/5.0129990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The local hydration around tetrameric hemoglobin (Hb) in its T0 and R4 conformational substates is analyzed based on molecular dynamics simulations. Analysis of the local hydrophobicity (LH) for all residues at the α1β2 and α2β1 interfaces, responsible for the quaternary T → R transition, which is encoded in the Monod-Wyman-Changeux model, as well as comparison with earlier computations of the solvent accessible surface area, makes clear that the two quantities measure different aspects of hydration. Local hydrophobicity quantifies the presence and structure of water molecules at the interface, whereas "buried surface" reports on the available space for solvent. For simulations with Hb frozen in its T0 and R4 states, the correlation coefficient between LH and buried surface is 0.36 and 0.44, respectively, but it increases considerably if the 95% confidence interval is used. The LH with Hb frozen and flexible changes little for most residues at the interfaces but is significantly altered for a few select ones: Thr41α, Tyr42α, Tyr140α, Trp37β, Glu101β (for T0) and Thr38α, Tyr42α, Tyr140α (for R4). The number of water molecules at the interface is found to increase by ∼25% for T0 → R4, which is consistent with earlier measurements. Since hydration is found to be essential to protein function, it is clear that hydration also plays an essential role in allostery.
Collapse
Affiliation(s)
- Seyedeh Maryam Salehi
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Marco Pezzella
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Adam Willard
- Department of Chemistry MIT, Cambridge, Massachusetts 02139, USA
| | - Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Martin Karplus
- Department of Chemistry, Harvard University, Cambridge, Massachusetts 02138, USA
| |
Collapse
|
7
|
Cross-Correlated Motions in Azidolysozyme. Molecules 2022; 27:molecules27030839. [PMID: 35164105 PMCID: PMC8838508 DOI: 10.3390/molecules27030839] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 01/13/2022] [Accepted: 01/19/2022] [Indexed: 02/01/2023] Open
Abstract
The changes in the local and global dynamics of azide-labelled lysozyme compared with that of the wild type protein are quantitatively assessed for all alanine residues along the polypeptide chain. Although attaching -N3 to alanine residues has been considered to be a minimally invasive change in the protein it is found that depending on the location of the alanine residue, the local and global changes in the dynamics differ. For Ala92, the change in the cross-correlated motions are minimal, whereas attaching -N3 to Ala90 leads to pronounced differences in the local and global correlations as quantified by the cross-correlation coefficients of the Cα atoms. We also demonstrate that the spectral region of the asymmetric azide stretch distinguishes between alanine attachment sites, whereas changes in the low frequency, far-infrared region are less characteristic.
Collapse
|
8
|
Dynamics of camel and human hemoglobin revealed by molecular simulations. Sci Rep 2022; 12:122. [PMID: 34997093 PMCID: PMC8741986 DOI: 10.1038/s41598-021-04112-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 12/09/2021] [Indexed: 11/08/2022] Open
Abstract
Hemoglobin is one of the most widely studied proteins genetically, biochemically, and structurally. It is an oxygen carrying tetrameric protein that imparts the characteristic red color to blood. Each chain of hemoglobin harbors a heme group embedded in a hydrophobic pocket. Several studies have investigated structural variations present in mammalian hemoglobin and their functional implications. However, camel hemoglobin has not been thoroughly explored, especially from a structural perspective. Importantly, very little is known about how the heme group interacts with hemoglobin under varying conditions of osmolarity and temperature. Several experimental studies have indicated that the tense (T) state is more stable than the relaxed (R) state of hemoglobin under normal physiological conditions. Despite the fact that R state is less stable than the T state, no extensive structural dynamics studies have been performed to investigate global quaternary transitions of R state hemoglobin under normal physiological conditions. To evaluate this, several 500 ns all-atom molecular dynamics simulations were performed to get a deeper understanding of how camel hemoglobin behaves under stress, which it is normally exposed to, when compared to human hemoglobin. Notably, camel hemoglobin was more stable under physiological stress when compared to human hemoglobin. Additionally, when compared to camel hemoglobin, cofactor-binding regions of hemoglobin also exhibited more fluctuations in human hemoglobin under the conditions studied. Several differences were observed between the residues of camel and human hemoglobin that interacted with heme. Importantly, distal residues His58 of α hemoglobin and His63 of β hemoglobin formed more sustained interactions, especially at higher temperatures, in camel hemoglobin. These residues are important for oxygen binding to hemoglobin. Thus, this work provides insights into how camel and human hemoglobin differ in their interactions under stress.
Collapse
|
9
|
Meuwly M, Karplus M. The functional role of the hemoglobin-water interface. Mol Aspects Med 2021; 84:101042. [PMID: 34756740 DOI: 10.1016/j.mam.2021.101042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 09/27/2021] [Indexed: 02/06/2023]
Abstract
The interface between hemoglobin (Hb) and its environment, in particular water, is of great physiological relevance. Here, results from in vitro, in vivo, and computational experiments (molecular dynamics simulations) are summarized and put into perspective. One of the main findings from the computations is that the stability of the deoxy, ligand-free T-state (T0) can be stabilized relative to the deoxy R-state (R0) only in sufficiently large simulation boxes for the hydrophobic effect to manifest itself. This effect directly influences protein stability and is operative also under physiological conditions. Furthermore, molecular simulations provide a dynamical interpretation of the Perutz model for Hb function. Results from experiments using higher protein concentrations and realistic cellular environments are also discussed. One of the next great challenges for computational studies, which as we show is likely to be taken up in the near future, is to provide a molecular-level understanding of the dynamics of proteins in such crowded environments.
Collapse
Affiliation(s)
- Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056, Basel, Switzerland; Department of Chemistry, Brown University, Providence RI, USA.
| | - Martin Karplus
- Department of Chemistry, Harvard University, USA; Laboratoire de Chimie Biophysique, ISIS, Université de Strasbourg, 67000, Strasbourg, France.
| |
Collapse
|
10
|
Maity D, Pal D. Molecular Dynamics of Hemoglobin Reveals Structural Alterations and Explains the Interactions Driving Sickle Cell Fibrillation. J Phys Chem B 2021; 125:9921-9933. [PMID: 34459602 DOI: 10.1021/acs.jpcb.1c01684] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In sickle cell anemia, deoxyhemoglobin deforms RBCs by forming fibrils inside that disintegrate on oxygenation. We studied 100 ns long all-atom molecular dynamics (MD) for sickle and normal hemoglobin fibril models to understand this process, complemented by multiple 1 μs MD for a single tetramer of sickle and normal hemoglobin in deoxy and oxy states. We find that the presence of hydrophobic residues without a bulky side chain at β-6 in hemoglobin is the reason for the stability of the fibrils. Moreover, the free energy landscapes from MD of hemoglobin starting in the tensed (T) state capture the putative transition from T to relaxed (R) state, associated with oxygen binding. The three conformational wells in the landscapes are characterized by the quaternary changes where one αβ dimer rotates with respect to the other. The conformational changes from the oxygenation of sickle hemoglobin hinder the intermolecular contacts necessary for fibril formation.
Collapse
Affiliation(s)
- Dibyajyoti Maity
- Department of Computational and Data Sciences, Indian Institute of Science, Bangalore 560012, Karnataka, India
| | - Debnath Pal
- Department of Computational and Data Sciences, Indian Institute of Science, Bangalore 560012, Karnataka, India
| |
Collapse
|
11
|
Adams E, Pezzotti S, Ahlers J, Rüttermann M, Levin M, Goldenzweig A, Peleg Y, Fleishman SJ, Sagi I, Havenith M. Local Mutations Can Serve as a Game Changer for Global Protein Solvent Interaction. JACS AU 2021; 1:1076-1085. [PMID: 34337607 PMCID: PMC8317155 DOI: 10.1021/jacsau.1c00155] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Indexed: 05/15/2023]
Abstract
Although it is well-known that limited local mutations of enzymes, such as matrix metalloproteinases (MMPs), may change enzyme activity by orders of magnitude as well as its stability, the completely rational design of proteins is still challenging. These local changes alter the electrostatic potential and thus local electrostatic fields, which impacts the dynamics of water molecules close the protein surface. Here we show by a combined computational design, experimental, and molecular dynamics (MD) study that local mutations have not only a local but also a global effect on the solvent: In the specific case of the matrix metalloprotease MMP14, we found that the nature of local mutations, coupled with surface morphology, have the ability to influence large patches of the water hydrogen-bonding network at the protein surface, which is correlated with stability. The solvent contribution can be experimentally probed via terahertz (THz) spectroscopy, thus opening the door to the exciting perspective of rational protein design in which a systematic tuning of hydration water properties allows manipulation of protein stability and enzymatic activity.
Collapse
Affiliation(s)
- Ellen
M. Adams
- Lehrstuhl
für Physkalische Chemie II, Ruhr
Universität Bochum, 44801 Bochum, Germany
| | - Simone Pezzotti
- Lehrstuhl
für Physkalische Chemie II, Ruhr
Universität Bochum, 44801 Bochum, Germany
| | - Jonas Ahlers
- Lehrstuhl
für Physkalische Chemie II, Ruhr
Universität Bochum, 44801 Bochum, Germany
| | - Maximilian Rüttermann
- Lehrstuhl
für Physkalische Chemie II, Ruhr
Universität Bochum, 44801 Bochum, Germany
| | - Maxim Levin
- Department
of Biological Regulation, Weizmann Institute
of Science, Rehovot 7610001, Israel
| | - Adi Goldenzweig
- Department
of Biomolecular Sciences, Weizmann Institute
of Science, Rehovot 7610001, Israel
| | - Yoav Peleg
- Structural
Proteomics Unit, Department of Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Sarel J. Fleishman
- Department
of Biomolecular Sciences, Weizmann Institute
of Science, Rehovot 7610001, Israel
| | - Irit Sagi
- Department
of Biological Regulation, Weizmann Institute
of Science, Rehovot 7610001, Israel
| | - Martina Havenith
- Lehrstuhl
für Physkalische Chemie II, Ruhr
Universität Bochum, 44801 Bochum, Germany
| |
Collapse
|
12
|
Nagatomo S, Kitagawa T, Nagai M. Roles of Fe-Histidine bonds in stability of hemoglobin: Recognition of protein flexibility by Q Sepharose. Biophys J 2021; 120:2734-2745. [PMID: 34087219 DOI: 10.1016/j.bpj.2021.05.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 04/22/2021] [Accepted: 05/07/2021] [Indexed: 11/24/2022] Open
Abstract
Using various mutants, we investigated to date the roles of the Fe-histidine (F8) bonds in cooperative O2 binding of human hemoglobin (Hb) and differences in roles between α- and β-subunits in the α2β2 tetramer. An Hb variant with a mutation in the heme cavity exhibited an unexpected feature. When the β mutant rHb (βH92G), in which the proximal histidine (His F8) of the β-subunit is replaced by glycine (Gly), was subjected to ion-exchange chromatography (Q Sepharose column) and eluted with an NaCl concentration gradient in the presence of imidazole, yielded two large peaks, whereas the corresponding α-mutant, rHb (αH87G), gave a single peak similar to Hb A. The β-mutant rHb proteins under each peak had identical isoelectric points according to isoelectric focusing electrophoresis. Proteins under each peak were further characterized by Sephadex G-75 gel filtration, far-UV CD, 1H NMR, and resonance Raman spectroscopy. We found that rHb (βH92G) exists as a mixture of αβ-dimers and α2β2 tetramers, and that hemes are released from β-subunits in a fraction of the dimers. An approximate amount of released hemes were estimated to be as large as 30% with Raman relative intensities. It is stressed that Q Sepharose columns can distinguish differences in structural flexibility of proteins having identical isoelectric points by altering the exit rates from the porous beads. Thus, the role of Fe-His (F8) bonds in stabilizing the Hb tetramer first described by Barrick et al. was confirmed in this study. In addition, it was found in this study that a specific Fe-His bond in the β-subunit minimizes globin structural flexibility.
Collapse
Affiliation(s)
- Shigenori Nagatomo
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
| | - Teizo Kitagawa
- Picobiology Institute, Graduate School of Life Science, University of Hyogo, Ako-gun, Hyogo, Japan.
| | - Masako Nagai
- Research Center for Micro-Nano Technology, Hosei University, Koganei, Tokyo, Japan; School of Health Sciences, College of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Ishikawa, Japan
| |
Collapse
|
13
|
Wan S, Sinclair RC, Coveney PV. Uncertainty quantification in classical molecular dynamics. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2021; 379:20200082. [PMID: 33775140 PMCID: PMC8059622 DOI: 10.1098/rsta.2020.0082] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/02/2020] [Indexed: 05/24/2023]
Abstract
Molecular dynamics simulation is now a widespread approach for understanding complex systems on the atomistic scale. It finds applications from physics and chemistry to engineering, life and medical science. In the last decade, the approach has begun to advance from being a computer-based means of rationalizing experimental observations to producing apparently credible predictions for a number of real-world applications within industrial sectors such as advanced materials and drug discovery. However, key aspects concerning the reproducibility of the method have not kept pace with the speed of its uptake in the scientific community. Here, we present a discussion of uncertainty quantification for molecular dynamics simulation designed to endow the method with better error estimates that will enable it to be used to report actionable results. The approach adopted is a standard one in the field of uncertainty quantification, namely using ensemble methods, in which a sufficiently large number of replicas are run concurrently, from which reliable statistics can be extracted. Indeed, because molecular dynamics is intrinsically chaotic, the need to use ensemble methods is fundamental and holds regardless of the duration of the simulations performed. We discuss the approach and illustrate it in a range of applications from materials science to ligand-protein binding free energy estimation. This article is part of the theme issue 'Reliability and reproducibility in computational science: implementing verification, validation and uncertainty quantification in silico'.
Collapse
Affiliation(s)
- Shunzhou Wan
- Centre for Computational Science, University College London, Gordon Street, London WC1H 0AJ, UK
| | - Robert C. Sinclair
- Centre for Computational Science, University College London, Gordon Street, London WC1H 0AJ, UK
| | - Peter V. Coveney
- Centre for Computational Science, University College London, Gordon Street, London WC1H 0AJ, UK
- Institute for Informatics, Science Park 904, University of Amsterdam, 1098 XH Amsterdam, The Netherlands
| |
Collapse
|
14
|
Abstract
The spectroscopic response of and structural dynamics around all azido-modified alanine residues (AlaN3) in lysozyme are characterized. It is found that AlaN3 is a positionally sensitive probe for the local dynamics, covering a frequency range of ∼15 cm-1 for the center frequency of the line shape. This is consistent with findings from selective replacements of amino acids in PDZ2, which reported a frequency span of ∼10 cm-1 for replacements of Val, Ala, or Glu by azidohomoalanine. For the frequency fluctuation correlation functions, the long-time decay constants τ2 range from ∼1 to ∼10 ps, which compares with experimentally measured correlation times of 3 ps. Attaching azide to alanine residues can yield dynamics that decays to zero on the few ps time scale (i.e., static component Δ0 ∼ 0 ps-1) or to a remaining, static contribution of ∼0.5 ps-1 (corresponding to 2.5 cm-1), depending on the local environment on the 10 ps time scale. The magnitude of the static component correlates qualitatively with the degree of hydration of the spectroscopic probe. Although attaching azide to alanine residues is found to be structurally minimally invasive with respect to the overall protein structure, analysis of the local hydrophobicity indicates that the hydration around the modification site differs for modified and unmodified alanine residues, respectively.
Collapse
Affiliation(s)
- Seyedeh Maryam Salehi
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| |
Collapse
|
15
|
Cui AY, Cui Q. Modulation of Nanoparticle Diffusion by Surface Ligand Length and Charge: Analysis with Molecular Dynamics Simulations. J Phys Chem B 2021; 125:4555-4565. [PMID: 33881853 DOI: 10.1021/acs.jpcb.1c01189] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To help better interpret experimental measurement of nanoparticle size, it is important to understand how their diffusion depends on the physical and chemical features of surface ligands. In this study, explicit solvent molecular dynamics simulations are used to probe the effect of ligand charge and flexibility on the diffusion of small gold nanoparticles. The results suggest that despite a high bare charge (+18 e), cationic nanoparticles studied here have reduced diffusion constants compared to a hydrophobic gold nanoparticle by merely a modest amount. Increasing the ligand length by 10 CH2 units also has a limited impact on the diffusion constant. For the three particles studied here, the difference between estimated hydrodynamic radius and radius of gyration is on the order of one solvent layer (3-5 Å), confirming that the significant discrepancies found in the size of similar nanoparticles by recent transmission electron microscopy and dynamic light scattering measurements were due to aggregation under solution conditions. The limited impact of electrostatic friction on the diffusion of highly charged nanoparticles is found to be due to the strong anticorrelation between electrostatic and van der Waals forces between nanoparticle and environment, supporting the generality of recent observation for proteins by Matyushov and co-workers. Including the first shell of solvent molecules as part of the diffusing particle has a minor impact on the total force autocorrelation function but reduces the disparity in relaxation time between the total force and its electrostatic and van der Waals components.
Collapse
Affiliation(s)
- Anthony Y Cui
- Weston High School, 444 Wellesley Street, Weston, Massachusetts 02493, United States
| | - Qiang Cui
- Departments of Chemistry, Physics, and Biomedical Engineering, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| |
Collapse
|
16
|
Gapsys V, de Groot BL. On the importance of statistics in molecular simulations for thermodynamics, kinetics and simulation box size. eLife 2020; 9:57589. [PMID: 32812868 PMCID: PMC7481008 DOI: 10.7554/elife.57589] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Accepted: 08/14/2020] [Indexed: 12/30/2022] Open
Abstract
Computational simulations, akin to wetlab experimentation, are subject to statistical fluctuations. Assessing the magnitude of these fluctuations, that is, assigning uncertainties to the computed results, is of critical importance to drawing statistically reliable conclusions. Here, we use a simulation box size as an independent variable, to demonstrate how crucial it is to gather sufficient amounts of data before drawing any conclusions about the potential thermodynamic and kinetic effects. In various systems, ranging from solvation free energies to protein conformational transition rates, we showcase how the proposed simulation box size effect disappears with increased sampling. This indicates that, if at all, the simulation box size only minimally affects both the thermodynamics and kinetics of the type of biomolecular systems presented in this work.
Collapse
Affiliation(s)
- Vytautas Gapsys
- Computational Biomolecular Dynamics Group, Max-Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Bert L de Groot
- Computational Biomolecular Dynamics Group, Max-Planck Institute for Biophysical Chemistry, Göttingen, Germany
| |
Collapse
|