Аннотация:Since the serine proteases form the most thoroughly understood family of enzymes, it is of some interest to consider what the two principal physical techniques of studying enzymes, crystallography and nuclear magnetic resonance (NMR), have told us about the details of their enzymatic mechanism. Due to limitations of space, this review cannot be compre hensive nor can it describe the history of the current ideas concerning the action of these enzymes. Two major issues have attracted the attention of both diffraction and NMR studies in the past ten years: the first concerns the nature and the role of the catalytic triad of serine 195, histidine 57, and aspartic acid 102; the second is the possibility of induced distortions upon complexa tion of either the substrate or the enzyme. We first consider these issues in terms of the crystallographic studies and then of the NMR experi ments. Finally, we interpret these results in terms of a detailed structural and electronic mechanism. Our conclusions, subject to further test, are that the triad does not exist in the resting state of the enzyme because the serine-histidine bond is not formed. However, we suggest that this bond does form upon complexation with substrates allowing the triad to play an important role in catalysis.
