Reactivity and Function of Carboxyl Groups in Bacterial and Fungal Proteinases (Subtilases): Relation to X—Ray Models

ABSTRACT

Carboxyl groups in five proteinases from microorganisms, the bacterial mesentericopeptidase, subtilisin DY and subtilisin Carlsberg as well as the fungal proteinase K and thermitase were modified with glycinamide in the presence of water soluble carbodiimide. Computer graphic studies using crystallographic models of the investigated proteinases showed a reasonably good correlation between the chemical reactivity of the carboxyl groups on one side and the degree of their exposure to the solvent or participation in ionic interactions, on the other. Differences in the binding of a large protein substrate by proteinases from microorganisms belonging to two subgroups are discussed.