Protein dynamics studied by neutron scattering

Abstract

This review of protein dynamics studied by neutron scattering focuses on data collected in the last 10 years. After an introduction to thermal neutron scattering and instrumental aspects, theoretical models that have been used to interpret the data are presented and discussed. Experiments are described according to sample type, protein powders, solutions and membranes. Neutron-scattering results are compared to those obtained from other techniques. The biological relevance of the experimental results is discussed. The major conclusion of the last decade concerns the strong dependence of internal dynamics on the macromolecular environment.

From shell to cell: neutron scattering studies of biological water dynamics and coupling to activity

“…By combining EINS data from two spectrometers, Gabel and Bellissent-Funel 8 reported diffusion coefficients of deuterated C-Phycocyanin hydration water, in the presence of trehalose molecules, which are slowed down by a factor of 10-15 with respect to bulk water. As has been pointed out, however, in Gabel et al 9 and by Gabel and Bellissent-Funel 8 , results obtained at different energy resolutions, different wave vector transfers and using different fit models are not directly comparable.…”

Dynamics of an antibiotic oligopeptide

“…It was not possible in this experiment, for technical reasons, to record spectra below 99 K. The quality of the spectra from (1) is such that small inelastic intensity differences down to a few 10 À4 of S(Q, 0) are analysable with confidence. By contrast, individual spectra from the continuous T-scan are statistically poor in the inelastic region proper, but their window-integrated quasielastic intensities are comparable in quality to data from scans using the backscattering spectrometer IN13 at ILL [2], providing S qe (Q; T) functions over a fine temperature grid in the region where the dynamics begins to be affected by softer modes and anharmonic interactions.…”

“…1) : first one up to E150 K, then a 'ledge' region with a roughly linear dependence up to E235 K, and finally a steep nonlinear rise similar to that in some globular proteins. Quantitative analysis of the latter two regions in terms of the models mentioned requires data up to at least 5 Å À1 to allow extraction of parameters additional to the Gaussian DW term which dominates for To235 K. Comparisons with high-resolution backscattering data for small proteins [1][2][3] show that overall the /u p 2 S values for H 2 O-hydrated CM15 are larger by factors between 1.1 and 1.3, due in part to the wider proton time scale range sampled in our experiment (quasielastic window70.2 meV), and in part to the fact that relative to tightly folded globular proteins (such as crambin [3] or BPTI), our hybrid oligopeptide is likely to retain more hydration-induced sidechain mobility at low temperatures (5 of the 15 amino acid residues are lysine, and there are 13 CH 3 groups). This qualitative interpretation appears to be corroborated by the fact that we observe /u p 2 S differences between the hydrated and the 'dry' sample that are larger than in crambin.…”

“…The evolution of the energy landscape of proteins and peptides from low to near-ambient temperatures is a subject of central interest in current work on biodynamics [1,2]. Neutron techniques are uniquely suited to contribute data on the proton dynamics, either in the form of windowintegrated quasielastic intensities, S qe (Q; T), or as spectrally resolved dynamic structure factors, S(Q, o; T) (_Q ¼ momentum transfer, _o ¼ energy transfer).…”

“…Neutron techniques are uniquely suited to contribute data on the proton dynamics, either in the form of windowintegrated quasielastic intensities, S qe (Q; T), or as spectrally resolved dynamic structure factors, S(Q, o; T) (_Q ¼ momentum transfer, _o ¼ energy transfer). Most experiments on the low-temperature dynamics of proteins have aimed to derive mean-square proton amplitudes, /u p 2 S, from effective or modified Debye-Waller (DW) factors extracted from S qe (Q; T) functions measured at intermediate to high Q between E30 and 300 K [2]. In recent work, the emphasis has been increasingly on (i) examining the spectral changes responsible for deviations from idealised behaviour and (ii) bridging the interpretational gap between S qe (Q; T) studies of small biomolecular building blocks and those of proteins.…”