%0 Journal Article
%A Voets, Ilja K.
%A Cruz, Willemberg A.
%A Moitzi, Christian
%A Lindner, Peter
%A P. G. Arêas, Elizabeth
%A Schurtenberger, Peter
%D 2010
%T DMSO-Induced Denaturation of Hen Egg White Lysozyme
%U https://acs.figshare.com/articles/journal_contribution/DMSO_Induced_Denaturation_of_Hen_Egg_White_Lysozyme/2729419
%R 10.1021/jp103515b.s001
%2 https://ndownloader.figshare.com/files/4405414
%K DMSO volume fractions
%K DMSO volume fraction
%K Hen Egg White LysozymeWe report
%K apolar side groups
%K φ DMSO
%X We report on the size, shape, structure, and interactions of lysozyme in the ternary system lysozyme/DMSO/water at low protein concentrations. Three structural regimes have been identified, which we term the “folded” (0 < φDMSO < 0.7), “unfolded” (0.7 ≤ φDMSO < 0.9), and “partially collapsed” (0.9 ≤ φDMSO < 1.0) regime. Lysozyme resides in a folded conformation with an average radius of gyration of 1.3 ± 0.1 nm for φDMSO < 0.7 and unfolds (average Rg of 2.4 ± 0.1 nm) above φDMSO > 0.7. This drastic change in the protein’s size coincides with a loss of the characteristic tertiary structure. It is preceded by a compaction of the local environment of the tryptophan residues and accompanied by a large increase in the protein’s overall flexibility. In terms of secondary structure, there is a gradual loss of α-helix and concomitant increase of β-sheet structural elements toward φDMSO = 0.7, while an increase in φDMSO at even higher DMSO volume fractions reduces the presence of both α-helix and β-sheet secondary structural elements. Protein−protein interactions remain overall repulsive for all values of φDMSO. An attempt is made to relate these structural changes to the three most important physical mechanisms that underlie them: the DMSO/water microstructure is strongly dependent on the DMSO volume fraction, DMSO acts as a strong H-bond acceptor, and DMSO is a bad solvent for the protein backbone and a number of relatively polar side groups, but a good solvent for relatively apolar side groups, such as tryptophan.
%I ACS Publications