Water in Enzyme Catalysis as a Promoter and Chemical Reagent

Abstract

The concepts of the dynamic structure of globular proteins and its role in the enzyme catalysis are supported by a large body of experimental and theoretical data. This chapter provides multiple evidence of the influence of the environment, primarily water, on the molecular dynamics of enzyme active sites and its chemical behavior. The experiments carried out on dry and moistened powders and at the presence of trehalose and sucrose, which excluded any motion by the macromolecule as a whole revealed nanosecond intermolecular mobility consisting of movement of the relatively large and rigid parts of the protein macromolecules modulated by mobility of the surrounding water. Many kinetic and thermodynamic studies of enzyme reaction series reveal the existence of an activation enthalpy–entropy linear correlation, the enthalpy–entropy compensation effect (EECE). The EECE theoretical model and the effect experimental examples are described.