Abstract
Previous time resolved measurements had indicated that protons could propagate on the surface of a protein, or a membrane, by a special mechanism that enhances the shuttle of the proton towards a specific site [1]. It was proposed that a proper location of residues on the surface contributes to the proton shuttling function. In the present study, this notion was further investigated using molecular dynamics, with only the mobile charge replaced by Na+ and Cl− ions. A molecular dynamics simulation of a small globular protein (the S6 of the bacterial ribosome) was carried out in the presence of explicit water molecules and four pairs of Na+ and Cl− ions. A 10 ns simulation indicated that the ions and the protein's surface were in equilibrium, with rapid passage of the ions between the protein's surface and the bulk. Yet it was noted that, close to some domains, the ions extended their duration near the surface, suggesting that the local electrostatic potential prevented them from diffusing to the bulk. During the time frame in which the ions were detained next to the surface, they could rapidly shuttle between various attractor sites located under the electrostatic umbrella. Statistical analysis of molecular dynamics and electrostatic potential/entropy consideration indicated that the detainment state is an energetic compromise between attractive forces and entropy of dilution. The similarity between the motion of free ions next to a protein and the proton transfer on the protein's surface are discussed.
Key words: molecular dynamics, ions at interface, protein-salt interactions
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References
- Nachliel E., Gutman M., Tittor J., Oesterhelt D.Proton Transfer Dynamics on the Surface of the Late M State of Bacteriorhodopsin Biophys. J. 200283416–426.2002BpJ....83..416N [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bizzarri A.R., Cannistraro S. Molecular Dynamics of Water at the Protein-Solvent Interface. J. Phys. Chem. B. 2002;106:6617–6633. doi: 10.1021/jp020100m. [DOI] [Google Scholar]
- Makarov V., Pettitt B.M., Feig M. Solvation and Hydration of Proteins and Nucleic Acids: A Theoretical View of Simulation and Experiment. Acc. Chem. Res. 2002;35:376–384. doi: 10.1021/ar0100273. [DOI] [PubMed] [Google Scholar]
- Svergun D.I., Richard S., Koch M.H., Sayers Z., Kuprin S., Zaccai G.Protein Hydration in Solution: Experimental Observation by X-ray and Neutron Scattering Proc. Natl. Acad. Sci. U.S.A. 1998952267–2272. 10.1073/pnas.95.5.22671998PNAS...95.2267S [DOI] [PMC free article] [PubMed] [Google Scholar]
- Smith J.C., Merzel F., Verma C.S., Fischer S. Protein Hydration Water: Structure and Thermodynamics. J. Mol. Liquid. 2002;101:27–33. [Google Scholar]
- Schiffer C.A., van Gunsteren W.F. Accessibility and Order of Water Sites in and Around Proteins: A Crystallographic Time-Averaging Study. Proteins. 1999;36:501–511. doi: 10.1002/(SICI)1097-0134(19990901)36:4<501::AID-PROT14>3.0.CO;2-1. [DOI] [PubMed] [Google Scholar]
- Sanschagrin P.C., Kuhn L.A. Cluster Analysis of Consensus Water Sites in Thrombin and Trypsin Shows Conservation Between Serine Proteases and Contributions to Ligand Specificity. Protein Sci. 1998;7:2054–2064. doi: 10.1002/pro.5560071002. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fenimore P.W., Frauenfelder H., McMahon B.H., Parak F.G.Slaving: Solvent Fluctuations Dominate Protein Dynamics and Functions Proc. Natl. Acad. Sci. U.S.A. 20029916047–16051. 10.1073/pnas.2126378992002PNAS...9916047F [DOI] [PMC free article] [PubMed] [Google Scholar]
- Higo J., Nakasako M. Hydration Structure of Human Lysozyme Investigated by Molecular Dynamics Simulation and Cryogenic X-Ray Crystal Structure Analyses: On the Correlation Between Crystal Water Sites, Solvent Density, and Solvent Dipole. J. Comput. Chem. 2002;23:1323–1336. doi: 10.1002/jcc.10100. [DOI] [PubMed] [Google Scholar]
- Curtis R.A., Prausnitz J.M., Blanch H.W. Protein-Protein and Protein-Salt Interactions in Aqueous Protein Solutions Containing Concentrated Electrolytes. Biotechnol. Bioeng. 1998;57:11–21. doi: 10.1002/(SICI)1097-0290(19980105)57:1<11::AID-BIT2>3.0.CO;2-Y. [DOI] [PubMed] [Google Scholar]
- Scheiner S.Quantum Chemical Studies of Proton Transport Through Biomembranes Ann. N.Y. Acad. Sci. 1981367493–509.1981NYASA.367..493S [DOI] [PubMed] [Google Scholar]
- Gutman M., Huppert D., Nachliel E. Kinetic Studies of Proton Transfer in the Microenvironment of a Binding Site. Eur. J. Biochem. 1982;121:637–642. doi: 10.1111/j.1432-1033.1982.tb05833.x. [DOI] [PubMed] [Google Scholar]
- Paddock M.L., McPherson P.H., Feher G., Okamura M.Y.Pathway of Proton Tranfer in Bacterial Reaction Centers: Replacement of Serinve-L22 by Alanine Inhibits Electron and Proton Transfers Associated with Reduction of Quinone to Dihydroquinone Proc. Natl. Acad. Sci. U.S.A. 1990876803–6807.1990PNAS...87.6803P [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bashford D., Gerwert K. Electrostatic Calculations of the pKa Values of Ionizable Groups in Bacteriorhodopsin. J. Mol. Biol. 1992;224:473–486. doi: 10.1016/0022-2836(92)91009-E. [DOI] [PubMed] [Google Scholar]
- Heberle J., Riesle J., Thiedemann G., Oesterhelt D., Dencher N.A.Proton Migration Along the Membrane Surface and Retarded Surface to Bulk Transfer Nature 1994370379–382. 10.1038/370379a01994Natur.370..379H [DOI] [PubMed] [Google Scholar]
- McPherson P.H., Schonfeld M., Paddock M.L., Okamura M.Y., Feher G. Protonation and Free Energy Changes Associated with Formation of QBH2 in Native and Glu-L212→Gln Mutant Reaction Centers from Rhodobacter Sphaeroides. Biochemistry. 1994;33:1181–1193. doi: 10.1021/bi00171a018. [DOI] [PubMed] [Google Scholar]
- le Coutre J., Gerwert K. Kinetic Isotope Effects Reveal an Ice-Like and a Liquid-Phase-type Intramolecular Proton Transfer in Bacteriorhodopsin. FEBS Lett. 1996;398:333–336. doi: 10.1016/s0014-5793(96)01254-9. [DOI] [PubMed] [Google Scholar]
- Gutman M., Nachliel E. Time Resolved Dynamics of Proton Transfer in Proteinous Systems. Annu. Rev. Phys. Chem. 1997;48:329–356. doi: 10.1146/annurev.physchem.48.1.329. [DOI] [PubMed] [Google Scholar]
- Adelroth P., Paddock M.L., Sagle L.B., Feher G., Okamura M.Y.Identification of the Proton Pathway in Bacterial Reaction Centers: Both Protons Associated with Reduction of QB to QBH2 Share a Common Entry Point Proc. Natl. Acad. Sci. U.S.A. 20009713086–13091. 10.1073/pnas.2304395972000PNAS...9713086A [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zscherp C., Schlesinger R., Heberle J. Time-Resolved FT-IR Spectroscopic Investigation of the pH-Dependent Proton Transfer Reactions in the E194Q Mutant of Bacteriorhodopsin. Biochem. Biophys. Res. Commun. 2001;283:57–63. doi: 10.1006/bbrc.2001.4730. [DOI] [PubMed] [Google Scholar]
- Gutman M., Nachliel E., Mezer A., Noivirt O. Gauging of Local Micro-Environment at Protein Water Interface by Time-Resolved Single-Proton Transfer Reactions. Ann. Eur. Acad. Sci. 2003;1:75–107. [Google Scholar]
- Nachliel E., Gutman M. Kinetic Analysis of Proton Transfer Between Reactants Adsorbed to the Same Micelle. The Effect of Proximity on the Rate Constants. Eur. J. Biochem. 1984;143:83–88. doi: 10.1111/j.1432-1033.1984.tb08344.x. [DOI] [PubMed] [Google Scholar]
- Gutman M., Nachliel E., Bamberg E., Christensen B. Time-Resolved Protonation Dynamics of a Black Lipid Membrane Monitored by Capacitative Currents. Biochim. Biophys. Acta. 1987;905:390–398. doi: 10.1016/0005-2736(87)90468-8. [DOI] [PubMed] [Google Scholar]
- Checover S., Marantz Y., Nachliel E., Gutman M., Pfeiffer M., Tittor J., Oesterhelt D., Dencher N.A. Dynamics of the Proton Transfer Reaction on the Cytoplasmic Surface of Bacteriorhodopsin. Biochemistry. 2001;40:4281–4292. doi: 10.1021/bi002574m. [DOI] [PubMed] [Google Scholar]
- Tran-Thi T.H., Gustavsson T., Prayer C., Pommeret S., Hynes J.T.Primary Ultrafast Events Preceding the Photoinduced Proton Transfer from Pyranine to Water Chem. Phys. Lett 2000329421–430. 10.1016/S0009-2614(00)01037-X2000CPL...329..421T [DOI] [Google Scholar]
- Forster T., Volker S.Kinetics of Proton Transfer Reaction Involving Hydroxypyrene-Trisulfonate in Aqueous Solution by Nanosecond Laser Absorption Spectroscopy Chem. Phys. Lett. 1975341–5.1975CPL....34....1F [Google Scholar]
- Weller A. Excited State Proton Transfer. Prog. React. Kinet. 1961;1:198–214. [Google Scholar]
- Gutman M., Huppert D. Rapid pH and deltamuH+ Jump by Short Laser Pulse. J. Biochem. Biophys. Methods. 1979;1:9–19. doi: 10.1016/0165-022X(79)90042-3. [DOI] [PubMed] [Google Scholar]
- Checover S., Nachliel E., Dencher N.A., Gutman M. Mechanism of Proton Entry into the Cytoplasmic Section of the Proton-Conducting Channel of Bacteriorhodopsin. Biochemistry. 1997;36:13919–13928. doi: 10.1021/bi9717542. [DOI] [PubMed] [Google Scholar]
- Marantz Y., Nachliel E., Aagaard A., Brzezinski P., Gutman M.The Proton Collecting Function of the Inner Surface of Cytochrome C Oxidase from Rhodobacter Sphaeroides Proc. Natl. Acad. Sci. U.S.A. 1998958590–8595. 10.1073/pnas.95.15.85901998PNAS...95.8590M [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cohen B., Huppert D. Evidence for a Continuous Transition from Nonadiabatic to Adiabatic Proton Transfer Dynamics in Protic Solvents. J. Phys. Chem. A. 2001;105:2980–2988. [Google Scholar]
- Agalarov S.C., Prasad G.S., Funke P.M., Stout C.D., Williamson J.R.Structure of the S15,S6,S18-rRNA Complex: Assembly of the 30S Ribosome Central Domain Science 2000288107–112. 10.1126/science.288.5463.1072000Sci...288..107A [DOI] [PubMed] [Google Scholar]
- Lindahl E., Hess B., van der Spoel D. Gromacs 3.0: A Package for Molecular Simulation and Trajectory Analysis. J. Mol. Med. 2001;7:306–317. [Google Scholar]
- van Gunsteren W.F., Berendsen H.J.C. Gromos-87 Manual. Groningen: Biomos BV; 1987. [Google Scholar]
- van Buuren A.R., Marrink S.J., Berendsen H.J.C. A Molecular Dynamics Study of the Decane/Water Interface. J. Phys. Chem. 1993;97:9206–9212. doi: 10.1021/j100138a023. [DOI] [Google Scholar]
- Mark A.E., van Helden S.P., Smith P.E., Janssen L.H.M., van Gunsteren W.F. Convergence Properties of Free Energy Calculations: Alpha-Cyclodextrin Complexes as a Case Study. J. Am. Chem. Soc. 1994;116:6293–6302. doi: 10.1021/ja00093a032. [DOI] [Google Scholar]
- van Buuren A.R., Berendsen H.J.C. Molecular Dynamics Simulations of the Stability of a 22 Residue Alpha-Helix in Water and 30% Trifluoroethanol. Biopolymers. 1993;33:1159–1166. doi: 10.1002/bip.360330802. [DOI] [PubMed] [Google Scholar]
- Liu H., Muller-Plathe F., van Gunsteren W.F.A. Force Field for Liquid Dimethyl Sulfoxide and Liquid Proporties of Liquid Dimethyl Sulfoxide Calculated Using Molecular Dynamics Simulation. J. Am. Chem. Soc. 1995;117:4363–4366. [Google Scholar]
- Lindahl M., Svensson L.A., Liljas A., Sedelnikova S.E., Eliseikina I.A., Fomenkova N.P., Nevskaya N., Nikonov S.V., Garber M.B., Muranova T.A. Crystal Structure of the Ribosomal Protein S6 from Thermus Thermophilus. EMBO J. 1994;13:1249–1254. doi: 10.2210/pdb1ris/pdb. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Berman H.M., Westbrook J., Feng Z., Gilliland G., Bhat T.N., Weissig H., Shindyalov I.N., Bourne P.E. The Protein Data Bank. Nucleic Acids Res. 2000;28:235–242. doi: 10.1093/nar/28.1.235. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Berendsen H.J.C., Postma J.P.M., van Gunsteren W.F., Hermans J.Interaction Models for Water in Relation to Protein Hydration Nature 1969224175–177.5343518 [Google Scholar]
- van der Spoel D., Berendsen H.J.C. Molecular Dynamics Simulations of Leu-Enkephalin in Water and DMSO. Biophys. J. 1997;72:2032–2041. doi: 10.1016/S0006-3495(97)78847-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tieleman D.P., Berendsen H.J.C.Molecular Dynamics Simulations of a Fully Hydrated Dipalmitoylphosphatidylcholine Bilayer with Different Macroscopic Boundary Conditions and Parameters J. Chem. Phys. 19961054871–4880. 10.1063/1.4723231996JChPh.105.4871T [DOI] [Google Scholar]
- Hess B., Bekker H., Berendsen H.J.C., Fraaije J.G.E.M. LINCS: A Linear Constraint Solver for Molecular Simulations. J. Comp. Chem. 1997;18:1463–1472. [Google Scholar]
- Miyamoto S., Kollman P.A. SETTLE: An Analytical Version of the SHAKE and RATTLE Algorithms for Rigid Water Models. J. Comp. Chem. 1992;13:952–962. [Google Scholar]
- Berendsen H.J.C., Postma J.P.M., DiNola A., Haak J.R.Molecular Dynamics with Coupling to an External Bath J. Chem. Phys. 1984813684–3690. 10.1063/1.4481181984JChPh..81.3684B [DOI] [Google Scholar]
- Darden T., York D., Pedersen L.Particle Mesh Ewald: An N-log(N) Method for Ewald Sums in Large Systems J. Chem. Phys. 19939810089–10092. 10.1063/1.4643971993JChPh..9810089D [DOI] [Google Scholar]
- Baker N.A., Sept D., Joseph S., Holst M.J., McCammon J.A.Electrostatics of Nanosystems: Application to Microtubules and the Ribosome Proc. Natl. Acad. Sci. U.S.A. 20019810037–10041. 10.1073/pnas.1813423982001PNAS...9810037B [DOI] [PMC free article] [PubMed] [Google Scholar]
- Humphrey W., Dalke A., Schulten K. VMD: Visual Molecular Dynamics. J. Mol. Gr. 1996;14:33–38. doi: 10.1016/0263-7855(96)00018-5. [DOI] [PubMed] [Google Scholar]
- van der Spoel D., van Maaren P.J., Berendsen H.J.C.A Systematic Study of Water Models for Molecular Simulation: Derivation of Water Models Optimized for Use with a Reaction Field J. Chem. Phys. 199810810220–10230. 10.1063/1.4764821998JChPh.10810220V [DOI] [Google Scholar]
- Harned S.H., Hildreth C.L. The Differential Diffusion Coefficients of Lithium and Sodium Chlorides in Dilute Aqueous Solution at 25 degrees. J. Am. Chem. Soc. 1951;73:650–652. [Google Scholar]
- Stokes R.H. The Diffusion Coefficients of Eight Uni-Univalent Electrolytes in Aqueous Solution at 25. J. Am. Chem. Soc. 1950;72:2243–2247. [Google Scholar]
- Macdonald P.M., Seelig J. Anion Binding to Neutral and Positively Charged Lipid Membranes. Biochemistry. 1988;27:6769–6775. doi: 10.1021/bi00418a019. [DOI] [PubMed] [Google Scholar]
- Pandit S.A., Bostic D., Berkowitz M.L. Molecular Dynamics Simulation of a Dipalmitoylphosphatidylcholine Bilayer with NaCl. Biophys. J. 2003;84:3743–3750. doi: 10.1016/S0006-3495(03)75102-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Froloff N., Windemuth A., Honig B. On the Calculation of Binding Free Energies Using Continuum Methods: Application to MHC Class I Protein-Peptide Interactions. Protein Sci. 1997;6:1293–1301. doi: 10.1002/pro.5560060617. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Miyashita O., Onuchic J.N., Okamura M.Y. Continuum Electrostatic Model for the Binding of Cytochrome c2 to the Photosynthesis Reaction Center from Rhodobacter Sphaeroides. Biochemistry. 2003;42:11651–11660. doi: 10.1021/bi0350250. [DOI] [PubMed] [Google Scholar]
- Marantz Y., Einarsdottir O.O., Nachliel E., Gutman M. Proton-Collecting Properties of Bovine Heart Cytochrome C Oxidase: Kinetic and Electrostatic Analysis. Biochemistry. 2001;40:15086–15097. doi: 10.1021/bi010453w. [DOI] [PubMed] [Google Scholar]
- Agmon N.The Grotthuss Mechanism Chem. Phys. Lett. 1995244456–462. 10.1016/0009-2614(95)00905-J1995CPL...244..456A [DOI] [Google Scholar]