Nanosecond motions in proteins impose bounds on the timescale distributions of local dynamics

Okan, Osman Burak and Atılgan, Ali Rana and Atılgan, Canan (2009) Nanosecond motions in proteins impose bounds on the timescale distributions of local dynamics. Biophysical Journal, 97 (7). pp. 2080-2088. ISSN 0006-3495

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We elucidate the physics of protein dynamical transition via 10-100-ns molecular dynamics simulations at temperatures spanning 160-300 K. By tracking the energy fluctuations, we show that the protein dynamical transition is marked by a crossover from nonstationary to stationary processes that underlie the dynamics of protein motions. A two-timescale function captures the nonexponential character of backbone structural relaxations. One timescale is attributed to the collective segmental motions and the other to local relaxations. The former is well defined by a single-exponential, nanosecond decay, operative at all temperatures. The latter is described by a set of processes that display a distribution of timescales. Although their average remains on the picosecond timescale, the distribution is markedly contracted at the onset of the transition. It is shown that the collective motions impose bounds on timescales spanned by local dynamical processes. The nonstationary character below the transition implicates the presence of a collection of substates whose interactions are restricted. At these temperatures, a wide distribution of local-motion timescales, extending beyond that of nanoseconds, is observed. At physiological temperatures, local motions are confined to timescales faster than nanoseconds. This relatively narrow window makes possible the appearance of multiple channels for the backbone dynamics to operate.
Item Type: Article
Subjects: Q Science > Q Science (General)
Divisions: Faculty of Engineering and Natural Sciences
Depositing User: Canan Atılgan
Date Deposited: 29 Oct 2009 22:04
Last Modified: 23 Jul 2019 12:07

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