A Complete Library of Amino Acid Alterations at N304 in Streptomyces clavuligerus Deacetoxycephalosporin C Synthase Elucidates the Basis for Enhanced Penicillin Analogue Conversion

N304 of Streptomyces clavuligerus deacetoxycephalosporin C synthase was mutagenized to alter its catalytic ability. Given that N304A, N304K, N304L, and N304R mutant enzymes exhibited significant improvements in penicillin analogue conversions, we advocate that replacement of N304 with residues with aliphatic or basic side chains is preferable for engineering of a hypercatalytic enzyme.