Evidence of Protein Collective Motions on the Picosecond Timescale

He, Y.; Chen, J.Y.; Knab, J.R.; Zheng, W.; Markelz, A.G.

doi:doi:10.1016/j.bpj.2010.12.3731

Evidence of Protein Collective Motions on the Picosecond Timescale

Title

Evidence of Protein Collective Motions on the Picosecond Timescale

Author

He, Y.
Chen, J.Y.
Knab, J.R.
Zheng, W.
Markelz, A.G.

Faculty

Applied Sciences

Department

Imaging Science and Technology

Date

2011-02-16

Abstract

We investigate the presence of structural collective motions on a picosecond timescale for the heme protein, cytochrome c, as a function of oxidation and hydration, using terahertz (THz) time domain spectroscopy and molecular dynamics simulations. The THz response dramatically increases with oxidation, with the largest increase for lowest hydrations, and highest frequencies. For both oxidation states the THz response rapidly increases with hydration saturating above ?25% (g H2O/g protein). Quasiharmonic vibrational modes and dipole-dipole correlation functions were calculated from molecular dynamics trajectories. The collective mode density of states alone reproduces the measured hydration dependence, providing strong evidence of the existence of these motions. The large oxidation dependence is reproduced only by the dipole-dipole correlation function, indicating the contrast arises from diffusive motions consistent with structural changes occurring in the vicinity of buried internal water molecules. This source for the observed oxidation dependence is consistent with the lack of an oxidation dependence in nuclear resonant vibrational spectroscopy measurements.

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DOI

https://doi.org/10.1016/j.bpj.2010.12.3731

Publisher

Elsevier

ISSN

0006-3495

Source

Biophysical Journal, 100 (4), 2011

Part of collection

Institutional Repository