Studies on Pepsin Mutagenesis and Recombinant Rhizopuspepsinogen
During the past fifteen years, many chemical and three-dimensional structures of aspartic proteases have been determined. It is now clear that, in spite of some diverse substrate specificities, these enzymes are alike in many ways, including their folding patterns, active center structures, and mechanisms of zymogen activation. Because the catalytic apparatuses of these enzymes are nearly identical, it is obvious that this group of enzymes shares a common catalytic mechanism. Although a number of catalytic mechanisms have been proposed for the aspartic proteases after consideration of kinetic and structural results (Fruton, 1976; James et al, 1977; Davies, 1990), a consensus on the mechanism has not emerged. One of the reasons for the uncertainty is that static structural information suggests, but does not provide, direct evidence for a mechanism of catalysis. On the other hand, kinetic experiments suggest reaction schemes but do not pinpoint structural components which are operational. It seems clear that additional experimental information is necessary to link structural information to reaction schemes.
KeywordsAspartic Protease Mutant D32A Residual Proteolytic Activity Transition State Binding Active Center Structure
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