Modifying the specificity and activity of the Enterobacter cloacae P99 beta-lactamase by mutagenesis within an M13 phage vector

Mutagenesis within an M13 phage vector alters the specificity and activity of the Enterobacter cloacae P99 beta-lactamase. Mutations among positions 286-290 affect enzyme specificity for the 3'-substituted cephalosporins and stabilize the enzyme. Amino acids in the 286-290 region of E. cloacae enzyme play no part in the catalytic activity, though they are close to the active site of the enzyme. Michaelis-Menten kinetic analysis with cephalosporin indicates that amino acids in the region are susceptible to substitution.