Quantitative theory of structural relaxation in supercooled liquids and folded proteins

This article provides a brief, up-to-date review of the theory of activated relaxations in supercooled condensed systems, of Wolynes and coworkers. Supercooled liquids and frozen glasses are truly frustrated systems whose microscopic dynamics consist of cooperative motions, high in the energy spectrum of structural states, and well above the defect states of an ordered solid. There is a temperature below which activated processes dominate dynamics and thus a free energy landscape emerges, many of whose microscopic attributes can be computed. In addition to signature phenomena in supercooled liquids, we apply this microscopic picture to the phenomenon of slaving of large scale conformational changes of a folded protein, imbedded in a glass-forming solvent, to the solvent motions. The size of the basin encompassing the corresponding conformational substates will be deduced, based on kinetic measurements alone. Implications of the theory for interpreting computer simulations of glass-forming systems are discussed.