Influence of Chemical Chaperones on the Properties of Lysozyme and the Reaction Center Protein from <i>Rhodobacter sphaeroides</i>
The influence of three chemical chaperones: glycerol, 4-hexylresorcinol, and 5-methylresorcinol on the structure, equilibrium fluctuations, and the functional activity of the hydrophilic enzyme lysozyme and the transmembrane reaction center (RC) protein from Rb. sphaeroides in a broad range of concentrations has been studied. Selected chemical chaperones are strongly different by the structure and action on hydrophilic and membrane proteins. The influence of the chemical chaperones (except methylresorcinol) on the structure, dynamics, and functional properties of lysozyme and RC protein are well described within the frames of extended models of preferential hydration and preferential interaction of protein with a chemical chaperone. A molecule of hexylresorcinol consists of a hydrophobic (alkyl radical) and a hydrophilic (aromatic nuclus) moieties. This fact provides additional regulation of functional activity of lysozyme and RC by hexylresorcinol. The influence of methylresorcinol on proteins differs from that of glycerol and hexylresorcinol. Methylresorcinol interacts with the surface of lysozyme directly, not via water hydrogen bonds. This leads to a decrease in denaturation temperature Td, and an increase in the amplitude of equilibrium fluctuation, which allows him to be a powerful activator. Methylresorcinol interacts with the membrane RC protein only by the condensation of hydration water, which is negligible in the case of methylresorcinol. Therefore, methylresorcinol does not effect the functional properties of the RC protein. It was concluded that various chaperones at one and the same concentration and chaperones at different concentrations form diverse 3D structures of proteins, which differ by dynamic and functional characteristics.