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Dalton BA, Kiefer H, Netz RR. The role of memory-dependent friction and solvent viscosity in isomerization kinetics in viscogenic media. Nat Commun 2024; 15:3761. [PMID: 38704367 PMCID: PMC11069540 DOI: 10.1038/s41467-024-48016-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 04/18/2024] [Indexed: 05/06/2024] Open
Abstract
Molecular isomerization kinetics in liquid solvent depends on a complex interplay between the solvent friction acting on the molecule, internal dissipation effects (also known as internal friction), the viscosity of the solvent, and the dihedral free energy profile. Due to the absence of accurate techniques to directly evaluate isomerization friction, it has not been possible to explore these relationships in full. By combining extensive molecular dynamics simulations with friction memory-kernel extraction techniques we consider a variety of small, isomerising molecules under a range of different viscogenic conditions and directly evaluate the viscosity dependence of the friction acting on a rotating dihedral. We reveal that the influence of different viscogenic media on isomerization kinetics can be dramatically different, even when measured at the same viscosity. This is due to the dynamic solute-solvent coupling, mediated by time-dependent friction memory kernels. We also show that deviations from the linear dependence of isomerization rates on solvent viscosity, which are often simply attributed to internal friction effects, are due to the simultaneous violation of two fundamental relationships: the Stokes-Einstein relation and the overdamped Kramers prediction for the barrier-crossing rate, both of which require explicit knowledge of friction.
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Affiliation(s)
| | - Henrik Kiefer
- Freie Universität Berlin, Fachbereich Physik, Berlin, Germany
| | - Roland R Netz
- Freie Universität Berlin, Fachbereich Physik, Berlin, Germany.
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2
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Bley M, Dzubiella J. Nonequilibrium free energy during polymer chain growth. J Chem Phys 2022; 156:084902. [DOI: 10.1063/5.0080786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
During fast diffusion-influenced polymerization, nonequilibrium behavior of the polymer chains and the surrounding reactive monomers has been reported recently. Based on the laws of thermodynamics, the emerging nonequilibrium structures should be characterizable by some “extra free energy” (excess over the equilibrium Helmholtz free energy). Here, we study the nonequilibrium thermodynamics of chain-growth polymerization of ideal chains in a dispersion of free reactive monomers, using off-lattice, reactive Brownian dynamics computer simulations in conjunction with approximative statistical mechanics and relative entropy (Gibbs–Shannon and Kullback–Leibler) concepts. In the case of fast growing polymers, we indeed report increased nonequilibrium free energies Δ Fneq of several kB T compared to equilibrium and near-equilibrium, slowly growing chains. Interestingly, Δ Fneq is a non-monotonic function of the degree of polymerization and thus also of time. Our decomposition of the thermodynamic contributions shows that the initial dominant extra free energy is stored in the nonequilibrium inhomogeneous density profiles of the free monomer gas (showing density depletion and wakes) in the vicinity of the active center at the propagating polymer end. At later stages of the polymerization process, we report significant extra contributions stored in the nonequilibrium polymer conformations. Finally, our study implies a nontrivial relaxation kinetics and “restoring” of the extra free energy during the equilibration process after polymerization.
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Affiliation(s)
- Michael Bley
- Applied Theoretical Physics–Computational Physics, Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder Strasse 3, D-79104 Freiburg, Germany
| | - Joachim Dzubiella
- Applied Theoretical Physics–Computational Physics, Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder Strasse 3, D-79104 Freiburg, Germany
- Cluster of Excellence livMats@FIT–Freiburg Center for Interactive Materials and Bioinspired Technologies, Albert-Ludwigs-Universität Freiburg, Georges-Köhler-Allee 105, D-79110 Freiburg, Germany
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3
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Han Z, Hilburg SL, Alexander-Katz A. Forced Unfolding of Protein-Inspired Single-Chain Random Heteropolymers. Macromolecules 2022. [DOI: 10.1021/acs.macromol.1c02411] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Zexiang Han
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Shayna L. Hilburg
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Alfredo Alexander-Katz
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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Chae MK, Lee NK, Johner A, Park JM. The Measurement of Information and Free Energy in Mechanical-Force-Driven Coil-Globule Transitions. J Phys Chem B 2021; 125:4987-4997. [PMID: 33973787 DOI: 10.1021/acs.jpcb.1c01119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We study the role of information (the relative entropy) for polymers undergoing coil-globule transitions driven by a time-dependent force. Pulling experiments at various speeds are performed by Brownian dynamics simulations. We obtain the work distributions for the forward and time-reversed backward processes and information stored at the end of the nonequilibrium pulling processes. We present the systematic method to measure the information from the pulling experiments and extract the information by analyzing slowly relaxing modes. When the information is incorporated, the work distributions modified by the information allow access to the proper free energy via the formulation of the generalized fluctuation theorems even if the initial states of the forward and time-reversed backward processes are out of equilibrium. This demonstrates that the work-information conversion works well for a single-molecule system with many degrees of freedom.
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Affiliation(s)
- Min-Kyung Chae
- Department of Physics and Astronomy, Sejong University, Seoul, Korea
| | - Nam-Kyung Lee
- Department of Physics and Astronomy, Sejong University, Seoul, Korea
| | - Albert Johner
- Institute Charles Sadron, CNRS 23 Rue du Loess, 67034 Strasbourg cedex 2, France
| | - Jeong-Man Park
- Department of Physics, The Catholic University of Korea, Bucheon, Korea
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5
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Xia C, Kang W, Wang J, Wang W. Temperature Dependence of Internal Friction of Peptides. J Phys Chem B 2021; 125:2821-2832. [PMID: 33689339 DOI: 10.1021/acs.jpcb.0c09056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Internal friction is a valuable concept to describe the kinetics of proteins. As is well known, internal friction can be modulated by solvent features (such as viscosity). How can internal friction be affected by environmental temperature? The answer to this question is not evident. In the present work, we approach this problem with simulations on two model peptides. The thermodynamics and relaxation kinetics are characterized through long molecular dynamics simulations, with the viscosity modulated by varying the mass of solvent molecules. Based on the extrapolation to zero viscosity together with scaling of the relaxation time scales, we discover that internal friction is almost invariant at various temperatures. Controlled simulations further support the idea that internal friction is independent of environmental temperature. Comparisons between the two model peptides help us to understand the diverse phenomena in experiments.
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Affiliation(s)
- Chenliang Xia
- School of Physics, Nanjing University, Nanjing 210093, P.R.China.,National Laboratory of Solid State Microstructure, Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, P.R.China
| | - Wenbin Kang
- School of Public Health and Management, Hubei University of Medicine, Shiyan 442000, P.R. China
| | - Jun Wang
- School of Physics, Nanjing University, Nanjing 210093, P.R.China.,National Laboratory of Solid State Microstructure, Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, P.R.China
| | - Wei Wang
- School of Physics, Nanjing University, Nanjing 210093, P.R.China.,National Laboratory of Solid State Microstructure, Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, P.R.China
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Heidari M, Satarifard V, Mashaghi A. Mapping a single-molecule folding process onto a topological space. Phys Chem Chem Phys 2019; 21:20338-20345. [PMID: 31497825 DOI: 10.1039/c9cp03175h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Physics of protein folding has been dominated by conceptual frameworks including the nucleation-propagation mechanism and the diffusion-collision model, and none address the topological properties of a chain during a folding process. Single-molecule interrogation of folded biomolecules has enabled real-time monitoring of folding processes at an unprecedented resolution. Despite these advances, the topology landscape has not been fully mapped for any chain. Using a novel circuit topology approach, we map the topology landscape of a model polymeric chain. Inspired by single-molecule mechanical interrogation studies, we restrained the ends of a chain and followed fold nucleation dynamics. We find that, before the nucleation, transient local entropic loops dominate. Although the nucleation length of globules is dependent on the cohesive interaction, the ultimate topological states of the collapsed polymer are largely independent of the interaction but depend on the speed of the folding process. After the nucleation, transient topological rearrangements are observed that converge to a steady-state, where the fold grows in a self-similar manner.
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Affiliation(s)
- Maziar Heidari
- Leiden Academic Centre for Drug Research, Faculty of Mathematics and Natural Sciences, Leiden University, Leiden, The Netherlands.
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7
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Al-Obaidi H, Lawrence MJ, Buckton G. Atypical effects of incorporated surfactants on stability and dissolution properties of amorphous polymeric dispersions. ACTA ACUST UNITED AC 2016; 68:1373-1383. [PMID: 27696396 DOI: 10.1111/jphp.12645] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 08/24/2016] [Indexed: 11/30/2022]
Abstract
OBJECTIVES To understand the impact of ionic and non-ionic surfactants on the dissolution and stability properties of amorphous polymeric dispersions using griseofulvin (GF) as a model for poorly soluble drugs. METHODS Solid dispersions of the poorly water-soluble drug, griseofulvin (GF) and the polymers, poly(vinylpyrrolidone) (PVP) and poly(2-hydroxypropyl methacrylate) (PHPMA), have been prepared by spray drying and bead milling and the effect of the ionic and non-ionic surfactants, namely sodium dodecyl sulphate (SDS) and Tween-80, on the physico-chemical properties of the solid dispersions studied. KEY FINDINGS The X-ray powder diffraction data and hot-stage microscopy showed a fast re-crystallisation of GF. While dynamic vapour sorption (DVS) measurements indicated an increased water uptake, slow dissolution rates were observed for the solid dispersions incorporating surfactants. The order by which surfactants free dispersions were prepared seemed critical as indicated by DVS and thermal analysis. Dispersions prepared by milling with SDS showed significantly better stability than spray-dried dispersions (drug remained amorphous for more than 6 months) as well as improved dissolution profile. CONCLUSIONS We suggest that surfactants can hinder the dissolution by promoting aggregation of polymeric chains, however that effect depends mainly on how the particles were prepared.
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Affiliation(s)
| | - M Jayne Lawrence
- Institute of Pharmaceutical Science, King's College London, London, UK
| | - Graham Buckton
- The School of Pharmacy, University College London, London, UK
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Sashi P, Ramakrishna D, Bhuyan AK. Dispersion Forces and the Molecular Origin of Internal Friction in Protein. Biochemistry 2016; 55:4595-602. [DOI: 10.1021/acs.biochem.6b00500] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Pulikallu Sashi
- School of Chemistry, University of Hyderabad, Hyderabad 500 046, India
| | | | - Abani K. Bhuyan
- School of Chemistry, University of Hyderabad, Hyderabad 500 046, India
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9
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Radtke M, Lippok S, Rädler JO, Netz RR. Internal tension in a collapsed polymer under shear flow and the connection to enzymatic cleavage of von Willebrand factor. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2016; 39:32. [PMID: 26993993 DOI: 10.1140/epje/i2016-16032-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 02/01/2016] [Indexed: 06/05/2023]
Abstract
By means of Brownian hydrodynamics simulations we show that the tension distribution along the contour of a single collapsed polymer in shear flow is inhomogeneous and above a threshold shear rate exhibits a double-peak structure when hydrodynamic interactions are taken into account. We argue that the tension maxima close to the termini of the polymer chain reflect the presence of polymeric protrusions. We establish the connection to shear-induced globule unfolding and determine the scaling behavior of the maximal tensile forces and the average protrusion length as a function of shear rate, globule size, and cohesive strength. A quasi-equilibrium theory is employed in order to describe the simulation results. Our results are used to explain experimental data for the shear-sensitive enzymatic degradation of von Willebrand factor.
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Affiliation(s)
- Matthias Radtke
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany.
| | - Svenja Lippok
- Fakultät für Physik, der Ludwig-Maximilians-Universität München, Schellingstraße 4, 80799, München, Germany
| | - Joachim O Rädler
- Fakultät für Physik, der Ludwig-Maximilians-Universität München, Schellingstraße 4, 80799, München, Germany
| | - Roland R Netz
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
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10
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How osmolytes influence hydrophobic polymer conformations: A unified view from experiment and theory. Proc Natl Acad Sci U S A 2015; 112:9270-5. [PMID: 26170324 DOI: 10.1073/pnas.1511780112] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
It is currently the consensus belief that protective osmolytes such as trimethylamine N-oxide (TMAO) favor protein folding by being excluded from the vicinity of a protein, whereas denaturing osmolytes such as urea lead to protein unfolding by strongly binding to the surface. Despite there being consensus on how TMAO and urea affect proteins as a whole, very little is known as to their effects on the individual mechanisms responsible for protein structure formation, especially hydrophobic association. In the present study, we use single-molecule atomic force microscopy and molecular dynamics simulations to investigate the effects of TMAO and urea on the unfolding of the hydrophobic homopolymer polystyrene. Incorporated with interfacial energy measurements, our results show that TMAO and urea act on polystyrene as a protectant and a denaturant, respectively, while complying with Tanford-Wyman preferential binding theory. We provide a molecular explanation suggesting that TMAO molecules have a greater thermodynamic binding affinity with the collapsed conformation of polystyrene than with the extended conformation, while the reverse is true for urea molecules. Results presented here from both experiment and simulation are in line with earlier predictions on a model Lennard-Jones polymer while also demonstrating the distinction in the mechanism of osmolyte action between protein and hydrophobic polymer. This marks, to our knowledge, the first experimental observation of TMAO-induced hydrophobic collapse in a ternary aqueous system.
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Radtke M, Netz RR. Shear-enhanced adsorption of a homopolymeric globule mediated by surface catch bonds. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2015; 38:69. [PMID: 26123772 DOI: 10.1140/epje/i2015-15069-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2015] [Revised: 05/19/2015] [Accepted: 05/27/2015] [Indexed: 06/04/2023]
Abstract
The adsorption of a single collapsed homopolymer onto a planar smooth surface in shear flow is investigated by means of Brownian hydrodynamics simulation. While cohesive intra-polymer forces are modeled by Lennard-Jones potentials, surface-monomer interactions are described by stochastic bonds whose two-state kinetics is characterized by three parameters: bond formation rate, bond dissociation rate and an effective catch bond parameter that describes how the force acting on a surface-monomer bond influences the dissociation rate. We construct adsorption state diagrams as a function of shear rate and all three surface-monomer bond parameters. We find shear-induced adsorption in a small range of parameters for low dissociation and association rates and only when the surface-monomer bond is near the transition between slip and catch bond behavior. By mapping on a simple surface-monomer interaction model with conservative pair potentials we try to estimate the conservative potential parameters necessary to observe shear-induced surface adsorption phenomena.
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Affiliation(s)
- Matthias Radtke
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany.
| | - Roland R Netz
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
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12
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Ojala H, Ziedaite G, Wallin AE, Bamford DH, Hæggström E. Optical tweezers reveal force plateau and internal friction in PEG-induced DNA condensation. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2014; 43:71-9. [DOI: 10.1007/s00249-013-0941-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 12/14/2013] [Accepted: 12/20/2013] [Indexed: 10/25/2022]
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13
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Mishra A, Panwar AS, Chakrabarti B. Equilibrium Morphologies and Force Extension Behavior for Polymers with Hydrophobic Patches: Role of Quenched Disorder. MACROMOL THEOR SIMUL 2014. [DOI: 10.1002/mats.201300154] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Ankur Mishra
- Department of Metallurgical Engineering and Materials Science; Indian Institute of Technology Bombay; Powai, Mumbai 400076 India
- Department of Mathematical Sciences; Durham University; Durham DH1 3LE UK
- Isaac Newton Institute of Mathematical Sciences; 20 Clarkson Road Cambridge CB3 0EH UK
| | - Ajay Singh Panwar
- Department of Metallurgical Engineering and Materials Science; Indian Institute of Technology Bombay; Powai, Mumbai 400076 India
- Department of Mathematical Sciences; Durham University; Durham DH1 3LE UK
- Isaac Newton Institute of Mathematical Sciences; 20 Clarkson Road Cambridge CB3 0EH UK
| | - Buddhapriya Chakrabarti
- Department of Metallurgical Engineering and Materials Science; Indian Institute of Technology Bombay; Powai, Mumbai 400076 India
- Department of Mathematical Sciences; Durham University; Durham DH1 3LE UK
- Isaac Newton Institute of Mathematical Sciences; 20 Clarkson Road Cambridge CB3 0EH UK
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Erbaş A, Netz RR. Confinement-dependent friction in peptide bundles. Biophys J 2013; 104:1285-95. [PMID: 23528088 PMCID: PMC3602766 DOI: 10.1016/j.bpj.2013.02.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 12/06/2012] [Accepted: 02/07/2013] [Indexed: 11/17/2022] Open
Abstract
Friction within globular proteins or between adhering macromolecules crucially determines the kinetics of protein folding, the formation, and the relaxation of self-assembled molecular systems. One fundamental question is how these friction effects depend on the local environment and in particular on the presence of water. In this model study, we use fully atomistic MD simulations with explicit water to obtain friction forces as a single polyglycine peptide chain is pulled out of a bundle of k adhering parallel polyglycine peptide chains. The whole system is periodically replicated along the peptide axes, so a stationary state at prescribed mean sliding velocity V is achieved. The aggregation number is varied between k = 2 (two peptide chains adhering to each other with plenty of water present at the adhesion sites) and k = 7 (one peptide chain pulled out from a close-packed cylindrical array of six neighboring peptide chains with no water inside the bundle). The friction coefficient per hydrogen bond, extrapolated to the viscous limit of vanishing pulling velocity V → 0, exhibits an increase by five orders of magnitude when going from k = 2 to k = 7. This dramatic confinement-induced friction enhancement we argue to be due to a combination of water depletion and increased hydrogen-bond cooperativity.
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Affiliation(s)
- Aykut Erbaş
- Free University of Berlin, Fachbereich Physik, Berlin, Germany.
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