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Wang Y, An Y, Shmidov Y, Bitton R, Deshmukh SA, Matson JB. A combined experimental and computational approach reveals how aromatic peptide amphiphiles self-assemble to form ion-conducting nanohelices. MATERIALS CHEMISTRY FRONTIERS 2020; 4:3022-3031. [PMID: 33163198 PMCID: PMC7643854 DOI: 10.1039/d0qm00369g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Reported here is a combined experimental-computational strategy to determine structure-property-function relationships in persistent nanohelices formed by a set of aromatic peptide amphiphile (APA) tetramers with the general structure K S XEK S , where KS= S-aroylthiooxime modified lysine, X = glutamic acid or citrulline, and E = glutamic acid. In low phosphate buffer concentrations, the APAs self-assembled into flat nanoribbons, but in high phosphate buffer concentrations they formed nanohelices with regular twisting pitches ranging from 9-31 nm. Coarse-grained molecular dynamics simulations mimicking low and high salt concentrations matched experimental observations, and analysis of simulations revealed that increasing strength of hydrophobic interactions under high salt conditions compared with low salt conditions drove intramolecular collapse of the APAs, leading to nanohelix formation. Analysis of the radial distribution functions in the final self-assembled structures led to several insights. For example, comparing distances between water beads and beads representing hydrolysable KS units in the APAs indicated that the KS units in the nanohelices should undergo hydrolysis faster than those in the nanoribbons; experimental results verified this hypothesis. Simulation results also suggested that these nanohelices might display high ionic conductivity due to closer packing of carboxylate beads in the nanohelices than in the nanoribbons. Experimental results showed no conductivity increase over baseline buffer values for unassembled APAs, a slight increase (0.4 × 102 μS/cm) for self-assembled APAs under low salt conditions in their nanoribbon form, and a dramatic increase (8.6 × 102 μS/cm) under high salt conditions in their nanohelix form. Remarkably, under the same salt conditions, these self-assembled nanohelices conducted ions 5-10-fold more efficiently than several charged polymers, including alginate and DNA. These results highlight how experiments and simulations can be combined to provide insight into how molecular design affects self-assembly pathways; additionally, this work highlights how this approach can lead to discovery of unexpected properties of self-assembled nanostructures.
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Affiliation(s)
- Yin Wang
- Department of Chemistry, Virginia Tech Center for Drug Discovery, and Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA 24061, United States
| | - Yaxin An
- Department of Chemical Engineering, Virginia Tech, Blacksburg, VA 24061, United States
| | - Yulia Shmidov
- Department of Chemical Engineering and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Ronit Bitton
- Department of Chemical Engineering and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Sanket A Deshmukh
- Department of Chemical Engineering, Virginia Tech, Blacksburg, VA 24061, United States
| | - John B Matson
- Department of Chemistry, Virginia Tech Center for Drug Discovery, and Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA 24061, United States
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Mateos-Gil P, Tsortos A, Vélez M, Gizeli E. Monitoring structural changes in intrinsically disordered proteins using QCM-D: application to the bacterial cell division protein ZipA. Chem Commun (Camb) 2016; 52:6541-4. [DOI: 10.1039/c6cc02127a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Characterization of structural changes in an intrinsically disordered protein attached on a QCM-D, with a sensitivity of 1.8 nm or better.
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Affiliation(s)
- Pablo Mateos-Gil
- Instituto de Catálisis y Petroleoquímica (ICP-CSIC)
- 28049 Madrid
- Spain
| | | | - Marisela Vélez
- Instituto de Catálisis y Petroleoquímica (ICP-CSIC)
- 28049 Madrid
- Spain
| | - Electra Gizeli
- Institute of Molecular Biology & Biotechnology
- Heraklion
- Greece
- Department of Biology
- University of Crete
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3
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Carmichael SP, Shell MS. Entropic (de)stabilization of surface-bound peptides conjugated with polymers. J Chem Phys 2015; 143:243103. [DOI: 10.1063/1.4929592] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Affiliation(s)
- Scott P. Carmichael
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - M. Scott Shell
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, USA
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Zhao Q, Wang G, Yan K, Yan J, Wang J. Binder-free porous PEDOT electrodes for flexible supercapacitors. J Appl Polym Sci 2015. [DOI: 10.1002/app.42549] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Qiang Zhao
- College of Chemical Engineering; Sichuan University; Chengdu 610065 China
| | - Guixin Wang
- College of Chemical Engineering; Sichuan University; Chengdu 610065 China
| | - Kangping Yan
- College of Chemical Engineering; Sichuan University; Chengdu 610065 China
| | - Jixin Yan
- Postdoctoral Scientific Research Workstation; Jiangsu United Technology Group; Tongzhou 226361 China
| | - Jianzhong Wang
- Postdoctoral Scientific Research Workstation; Jiangsu United Technology Group; Tongzhou 226361 China
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5
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Wang Z, Han X, He N, Chen Z, Brooks CL. Environmental Effect on Surface Immobilized Biological Molecules. J Phys Chem B 2014; 118:12176-85. [DOI: 10.1021/jp508550d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Zunliang Wang
- State
Key Laboratory of Bioelectronics, School of Biological Science and
Medical Engineering, Southeast University, Si Pai Lou 2, Nanjing 210096, China
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Xiaofeng Han
- State
Key Laboratory of Bioelectronics, School of Biological Science and
Medical Engineering, Southeast University, Si Pai Lou 2, Nanjing 210096, China
| | - Nongyue He
- State
Key Laboratory of Bioelectronics, School of Biological Science and
Medical Engineering, Southeast University, Si Pai Lou 2, Nanjing 210096, China
| | - Zhan Chen
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Charles L. Brooks
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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Mereuta L, Asandei A, Seo CH, Park Y, Luchian T. Quantitative understanding of pH- and salt-mediated conformational folding of histidine-containing, β-hairpin-like peptides, through single-molecule probing with protein nanopores. ACS APPLIED MATERIALS & INTERFACES 2014; 6:13242-13256. [PMID: 25069106 DOI: 10.1021/am5031177] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Inter-amino acid residues electrostatic interactions contribute to the conformational stability of peptides and proteins, influence their folding pathways, and are critically important to a multitude of problems in biology including the onset of misfolding diseases. By varying the pH and ionic strength, the inter-amino acid residues electrostatic interactions of histidine-containing, β-hairpin-like peptides alter their folding behavior, and we studied this through quantifying, at the unimolecular level, the frequency, dwell-times of translocation events, and amplitude of blockades associated with interactions between such peptides and the α-hemolysin (α-HL) protein. Acidic buffers were shown to dramatically decrease the rate of peptide capture by the α-HL protein, through the interplay of enthalpic and entropic contributions brought about on the free energy barrier, which controls the peptides-α-HL association rate. We found that in acidic buffers, the amplitude of the blockage induced by an α-HL, β-barrel-residing peptide is smaller than the value seen at neutral pH, and this supports our interpretation of the pH-induced change in the conformation of the peptide, which behaves as a less-stable hairpin at acidic pH values that obstructs, to a lesser extent, the protein pore. This is also confirmed by the fact that the dissociation rate of such model peptide from the α-HL's β-barrel is higher at acidic, as compared to neutral, pH values. Experiments performed in low-salt buffers revealed the dramatic decrease of the peptide capture rate by the α-HL protein, most likely caused by the increase in the radius of counterions cloud around the peptide that hinders peptide partition into the α-barrel, and histidines protonation at low pH bolsters this effect. Reduced electrostatic screening in low-salt buffers, at neutral pH, leads to a decrease in peptides effective cross-sectional areas and an increase of their mobility inside the α-HL pore, due most likely to the chain stretching augmentation, via increased inter-residues electrostatic interactions.
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Affiliation(s)
- Loredana Mereuta
- Department of Physics, Alexandru I. Cuza University , Iasi 700506, Romania
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7
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Wang Z, Han X, He N, Chen Z, Brooks CL. Molecular Structures of C- and N-Terminus Cysteine Modified Cecropin P1 Chemically Immobilized onto Maleimide-Terminated Self-Assembled Monolayers Investigated by Molecular Dynamics Simulation. J Phys Chem B 2014; 118:5670-80. [DOI: 10.1021/jp5023482] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Zunliang Wang
- State
Key Laboratory of Bioelectronics, School of Biological Science and
Medical Engineering, Southeast University, Si Pai Lou 2, Nanjing 210096, China
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Xiaofeng Han
- State
Key Laboratory of Bioelectronics, School of Biological Science and
Medical Engineering, Southeast University, Si Pai Lou 2, Nanjing 210096, China
| | - Nongyue He
- State
Key Laboratory of Bioelectronics, School of Biological Science and
Medical Engineering, Southeast University, Si Pai Lou 2, Nanjing 210096, China
| | - Zhan Chen
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Charles L. Brooks
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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Alarcón F, Pérez-Hernández G, Pérez E, Gama Goicochea A. Coarse-grained simulations of the salt dependence of the radius of gyration of polyelectrolytes as models for biomolecules in aqueous solution. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2013; 42:661-72. [DOI: 10.1007/s00249-013-0915-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Revised: 05/07/2013] [Accepted: 05/15/2013] [Indexed: 11/30/2022]
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Goh GB, García-Moreno E B, Brooks CL. The high dielectric constant of staphylococcal nuclease is encoded in its structural architecture. J Am Chem Soc 2011; 133:20072-5. [PMID: 22085022 DOI: 10.1021/ja2084866] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The pK(a) values of Lys-66, Glu-66, and Asp-66 buried in the interior of the staphylococcal nuclease Δ+PHS variant were reported to be shifted by as much as 5 pK(a) units from their normal values. Reproducing the pK(a) of these buried ionizable residues using continuum electrostatic calculations required the use of a high protein dielectric constant of 10 or higher. The apparent high dielectric constant has been rationalized as a consequence of a local structural reorganization or increased fluctuations in the microenvironment of the mutation site (Chimenti, M. S., et al. J. Mol. Biol. 2011, 405, 361-377). We have calculated the dielectric constant of Δ+PHS and the Lys-66, Asp-66, and Glu-66 mutants from first principles using the Kirkwood-Fröhlich equation and discovered that staphylococcal nuclease has a naturally high dielectric constant ranging from 20 to 30. This high dielectric constant does not change significantly with the mutation of residue 66 or with the ionization of the mutated residues. Calculation of the spatial dependence of the dielectric constant for the microenvironment of residue-66 produces a value of about 10, which matches well with the apparent dielectric constant needed to reproduce pK(a) values from continuum electrostatic calculations. Our results suggest an alternative explanation that the high dielectric constant of staphylococcal nuclease is a property resulting from the intrinsic backbone fluctuations originating from its structural architecture.
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Affiliation(s)
- Garrett B Goh
- Department of Chemistry, University of Michigan, 930 North University, Ann Arbor, Michigan 48109, USA
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Fenley MO, Mascagni M, McClain J, Silalahi ARJ, Simonov NA. Using Correlated Monte Carlo Sampling for Efficiently Solving the Linearized Poisson-Boltzmann Equation Over a Broad Range of Salt Concentration. J Chem Theory Comput 2010; 6:300-314. [PMID: 20640228 PMCID: PMC2904251 DOI: 10.1021/ct9003806] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Dielectric continuum or implicit solvent models provide a significant reduction in computational cost when accounting for the salt-mediated electrostatic interactions of biomolecules immersed in an ionic environment. These models, in which the solvent and ions are replaced by a dielectric continuum, seek to capture the average statistical effects of the ionic solvent, while the solute is treated at the atomic level of detail. For decades, the solution of the three-dimensional Poisson-Boltzmann equation (PBE), which has become a standard implicit-solvent tool for assessing electrostatic effects in biomolecular systems, has been based on various deterministic numerical methods. Some deterministic PBE algorithms have drawbacks, which include a lack of properly assessing their accuracy, geometrical difficulties caused by discretization, and for some problems their cost in both memory and computation time. Our original stochastic method resolves some of these difficulties by solving the PBE using the Monte Carlo method (MCM). This new approach to the PBE is capable of efficiently solving complex, multi-domain and salt-dependent problems in biomolecular continuum electrostatics to high precision. Here we improve upon our novel stochastic approach by simultaneouly computating of electrostatic potential and solvation free energies at different ionic concentrations through correlated Monte Carlo (MC) sampling. By using carefully constructed correlated random walks in our algorithm, we can actually compute the solution to a standard system including the linearized PBE (LPBE) at all salt concentrations of interest, simultaneously. This approach not only accelerates our MCPBE algorithm, but seems to have cost and accuracy advantages over deterministic methods as well. We verify the effectiveness of this technique by applying it to two common electrostatic computations: the electrostatic potential and polar solvation free energy for calcium binding proteins that are compared with similar results obtained using mature deterministic PBE methods.
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Affiliation(s)
- Marcia O Fenley
- Department of Physics and Institute for Molecular Biophysics, Florida State University, Tallahassee, FL USA
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Feng J, Wong KY, Dyer K, Pettitt BM. Transport properties of water at functionalized molecular interfaces. J Chem Phys 2009; 131:125102. [PMID: 19791920 DOI: 10.1063/1.3224122] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Understanding transport properties of solvent such as diffusion and viscosity at interfaces with biomacromolecules and hard materials is of fundamental importance to both biology and biotechnology. Our study utilizes equilibrium molecular dynamics simulations to calculate solvent transport properties at a model peptide and microarray surface. Both diffusion and selected components of viscosity are considered. Solvent diffusion is found to be affected near the peptide and surface. The stress-stress correlation function of solvent near the hard surface exhibits long time memory. Both diffusion and viscosity are shown to be closely correlated with the density distribution function of water along the microarray surface.
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Affiliation(s)
- Jun Feng
- Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204-5001, USA
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