FTIR, ESI-MS, VT-NMR and SANS study of trehalose thermal stabilization of lysozyme

Abstract

Protein aggregation is often associated with conformational and structural changes of secondary structure elements that may lead to exposure of some specific residues. Data obtained in our experimental work indicate that trehalose (1.0M) effectively prevent thermal inactivation and aggregation of lysozyme. In fact, following heat treatment, lysozyme generates insoluble aggregates which are almost completely absent in the samples incubated in the presence of the disaccharide. The experimental approach consists in studying FTIR spectra of intrinsic chromophores and VT-NMR measurements on lysozyme water mixtures in the presence of trehalose. FTIR measurements suggest that in the presence of 1.0M of trehalose there is a clear decrease in the loss of α-helix structure and in the formation of intermolecularly aggregated structures. Electrospray ionization mass spectrometry (ESI-MS) was employed to characterize protein structural transition, highlighting as trehalose remarkably influenced solvent accessibility to the amide peptide backbone upon heat treatment, consequentially decreasing local protein environment changes. Complementary informations are also obtained by UV–vis spectroscopy measurements, Congo Red binding and activity determinations.