Direct Experimental Characterization of Contributions from Self-Motion of Hydrogen and from Interatomic Motion of Heavy Atoms to Protein Anharmonicity

Zhuo Liu, Chenxing Yang, Juan Huang, Gaia Ciampalini, Jun Li, Victoria García Sakai, Madhusudan Tyagi, Hugh O'Neill, Qiu Zhang, Simone Capaccioli, K. L. Ngai, Liang Hong

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

One fundamental challenge in biophysics is to understand the connection between protein dynamics and its function. Part of the difficulty arises from the fact that proteins often present local atomic motions and collective dynamics on the same time scales, and challenge the experimental identification and quantification of different dynamic modes. Here, by taking lyophilized proteins as the example, we combined deuteration technique and neutron scattering to separate and characterize the self-motion of hydrogen and the collective interatomic motion of heavy atoms (C, O, N) in proteins on the pico-to-nanosecond time scales. We found that hydrogen atoms present an instrument-resolution-dependent onset for anharmonic motions, which can be ascribed to the thermal activation of local side-group motions. However, the protein heavy atoms exhibit an instrument-resolution-independent anharmonicity around 200 K, which results from unfreezing of the relaxation of the protein structures on the laboratory equilibrium time (100-1000 s), softening of the entire bio-macromolecules.

Original languageEnglish
Pages (from-to)9956-9961
Number of pages6
JournalJournal of Physical Chemistry B
Volume122
Issue number43
DOIs
StatePublished - Nov 1 2018

Funding

This work was supported by NSF China 11504231 and 31630002 and the Innovation Program of Shanghai Municipal Education Commission. H.O’N. and Q.Z. acknowledge the support of Center for Structural Molecular Biology (FWP ERKP291) funded by the U.S. Department of Energy (DOE) Office of Biological and Environmental Research. Z.L. acknowledges the Visiting Student Program of University of Pisa supporting the stay at Pisa in Italy. Access to the HFBS was provided by the Center for High Resolution Neutron Scattering, a partnership between the National Institute of Standards and Technology and the National Science Foundation under Agreement No. DMR-1508249. Certain commercial products are identified in order to specify adequately the experimental procedure. In no case does such identification imply recommendation or endorsement by the NIST, nor does it imply that the products are necessarily the best for the purpose.

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