3.4.22.51 | E208A |
the mutant enzyme recognizes benzyloxycarbonyl-Phe-Arg-7-amido-4-methylcoumarin less effectively than wild-type cruzain does, turnover of the substrate is comparable, suggesting that once bound, mutant cruzain processes benzyloxycarbonyl-Phe-Arg-7-amido-4-methylcoumarinat rates similar to that of the wild-type enzyme. Diminutions by 300fold and 200fold in the kcat/Km values of benzyloxycarbonyl-Arg-Arg-7-amido-4-methylcoumarin and benzyloxycarbonyl-Arg-Ala-7-amido-4-methylcoumarin, respectively, are observed for the E208A mutant cruzain compared to that of the wild type, suggesting that ion pairing between Glu208 and P2 Arg is essential for recognition of these substrates. This is also reflected in values of Km, which are increased for benzyloxycarbonyl-Arg-Arg-7-amido-4-methylcoumarin (10fold) and benzyloxycarbonyl-Arg-Ala-7-amido-4-methylcoumarin (4fold) |
752781 |