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Biophys J. 2002 Aug;83(2):1157-64.

Effect of the environment on the protein dynamical transition: a neutron scattering study.

Author information

1
Istituto Nazionale per la Fisica della Materia, Dipartimento di Fisica dell'Università di Perugia, Perugia 06121, Italy. alessandro.paciaroni@fisica.unipg.it

Abstract

We performed an elastic neutron scattering investigation of the molecular dynamics of lysozyme solvated in glycerol, at different water contents h (grams of water/grams of lysozyme). The marked non-Gaussian behavior of the elastic intensity was studied in a wide experimental momentum transfer range, as a function of the temperature. The internal dynamics is well described in terms of the double-well jump model. At low temperature, the protein total mean square displacements exhibit an almost linear harmonic trend irrespective of the hydration level, whereas at the temperature T(d) a clear changeover toward an anharmonic regime marks a protein dynamical transition. The decrease of T(d) from approximately 238 K to approximately 195 K as a function of h is reminiscent of that found in the glass transition temperature of aqueous solutions of glycerol, thus suggesting that the protein internal dynamics as a whole is slave to the environment properties. Both T(d) and the total mean square displacements indicate that the protein flexibility strongly rises between 0.1 and 0.2h. This hydration-dependent dynamical activation, which is similar to that of hydrated lysozyme powders, is related to the specific interplay of the protein with the surrounding water and glycerol molecules.

PMID:
12124295
PMCID:
PMC1302217
DOI:
10.1016/S0006-3495(02)75239-9
[Indexed for MEDLINE]
Free PMC Article

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