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Protein surface hydration mapped by site-specific mutations

Qiu, Weihong and Kao, Ya-Ting and Zhang, Luyuan and Yang, Yi and Wang, Lijuan and Stites, Wesley E. and Zhong, Dongping and Zewail, Ahmed H. (2006) Protein surface hydration mapped by site-specific mutations. Proceedings of the National Academy of Sciences of the United States of America, 103 (38). pp. 13979-13984. ISSN 0027-8424. PMCID PMC1599899.

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[img] PDF (Fig. 6. Normalized femtosecond-resolved W140 fluorescence transients of SNase mutants K133A, E129A, K110C, and K100A on both short and long time scales. Note that, for each mutant, only three characteristic transients from >10 gated fluorescence ... ) - Supplemental Material
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[img] PDF (Fig. 7. Femtosecond-resolved emission maxima of the overall emission spectra (ns) and lifetime-associated emission spectra (nl) for WT Snase and mutants K133A, E129A, and K110C) - Published Version
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[img] PDF (Fig. 8. Femtosecond-resolved fluorescence anisotropy of W140 of WT SNase and four mutants. The initial ~100-fs decay is due to the internal conversion between the ^1L_a and ^1L_b states) - Published Version
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Water motion at protein surfaces is fundamental to protein structure, stability, dynamics, and function. By using intrinsic tryptophans as local optical probes, and with femtosecond resolution, it is possible to probe surface-water motions in the hydration layer. Here, we report our studies of local hydration dynamics at the surface of the enzyme Staphylococcus nuclease using site-specific mutations. From these studies of the WT and four related mutants, which change local charge distribution and structure, we are able to ascertain the contribution to solvation by protein side chains as relatively insignificant. We determined the time scales of hydration to be 3–5 ps and 100–150 ps. The former is the result of local librational/rotational motions of water near the surface; the latter is a direct measure of surface hydration assisted by fluctuations of the protein. Experimentally, these hydration dynamics of the WT and the four mutants are also consistent with results of the total dynamic Stokes shifts and fluorescence emission maxima and are correlated with their local charge distribution and structure. We discuss the role of protein fluctuation on the time scale of labile hydration and suggest reexamination of recent molecular dynamics simulations.

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Additional Information:© 2006 by the National Academy of Sciences. Contributed by Ahmed H. Zewail, July 25, 2006. Published online before print September 12, 2006, 10.1073/pnas.0606235103. We thank Prof. Patrik R. Callis for catalysis of the initial collaboration for the work with W.E.S. and for constructive comments on the manuscript, Bradford Bullock for help with preparing protein samples, Prof. Sherwin Singer for helpful discussion, Tanping Li for efforts in preparing Fig. 5, and Dr. Wenyun Lu for initial help with the experiments. This work was supported by Petroleum Research Fund Grant PRF-42734-G4, the Packard Foundation Fellowship (to D.Z.), National Science Foundation grants (to D.Z. and A.H.Z.), and National Institutes of Health Grant NCRR COBRE P20 RR15569 (to W.E.S.). Author contributions: D.Z. and A.H.Z. designed research; W.Q., Y.-T.K., L.Z., Y.Y., and L.W. performed research; W.E.S. contributed proteins; W.Q., Y.-T.K., and L.Z. analyzed data; and D.Z. and A.H.Z. wrote the paper. The authors declare no conflict of interest.
Funding AgencyGrant Number
American Chemical Society Petroleum Research FundPRF-42734-G4
David and Lucile Packard FoundationUNSPECIFIED
Subject Keywords:protein hydration; femtosecond dynamics; protein fluctuation; selective mutation
Issue or Number:38
PubMed Central ID:PMC1599899
Record Number:CaltechAUTHORS:QIUpnas06
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Official Citation:Weihong Qiu, Ya-Ting Kao, Luyuan Zhang, Yi Yang, Lijuan Wang, Wesley E. Stites, Dongping Zhong, and Ahmed H. Zewail Protein surface hydration mapped by site-specific mutations PNAS 2006 103 (38) 13979-13984; published ahead of print September 12, 2006, doi:10.1073/pnas.0606235103
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7776
Deposited By: Tony Diaz
Deposited On:16 Aug 2007
Last Modified:02 Oct 2019 23:45

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