Thermal behaviour of hydrated lysozyme in the presence of sucrose and trehalose by EINS

The main aim of the present work is to investigate the dynamical effects of the addition of disaccharides to hydrated lysozyme. The Self-Distribution-Function procedure is at first applied on Elastic Incoherent Neutron Scattering data obtained by the IN13 spectrometer on trehalose/H2O and sucrose/H2O where it highlights a different Q-dependence for the two disaccharides. Then a quantitative analysis of the Mean Square Displacement of lysozyme/trehalose/H2O and of lysozyme/sucrose/H2O from Elastic Incoherent Neutron Scattering data obtained by the IN10 spectrometer is presented. It is shown how the resolution function gives rise to a time integration of a given time-dependent Mean Square Displacement function. Furthermore the analysis shows that the protein dynamical transition, registered at a temperature value of about T = 200-220 K in the H2O hydrated lysozyme sample, is inhibited by the addition of the disaccharides. (C) 2010 Elsevier B.V. All rights reserved.