Mutagenesis, biochemical characterization and X-ray structural analysis of point mutants of bovine chymosin

ChymosinBpointmutants,A115TandG243D(chymosinA),were expressed in Escherichia coli and Trichoderma reeseirespectively, characterized biochemically, crystallized andstudied by X-ray analysis at 2.3 and 2.8 A resolutionsrespectively. The three-dimensional structures showed thatthe mutations gave rise to local conformational changesonly when compared with that of chymosin B. Kineticanalysis of the A115T mutant with a six residue syntheticpeptide revealed a reduction in K