The mechanism of reactions catalysed by the serine β-lactamases

Nucleophilic substitution at the β-lactam carbonyl of penicillins usually requires general base and acid catalysis and proceeds via the formation of a tetrahedral intermediate. A class C serine β-lactamase is inhibited by phosphonamidates, shows diastereoselectivity in P---O and P---O bond fission and exhibits enzyme catalysed nucleophilic displacement of proline. The requirements for general acid catalysed expulsion of proline have interesting stereochemical consequences.

Necleophilic substitution at the β-lactam carbonyl of penicillins usually requires general base and acid catalysis and proceeds via the formation of a tetrahedral intermediate. A class C serine β-lactamase is inhibited by phosphonamidates, shows diastereoselectivity in P---N and P---O bond fission and exhibits enzyme catalysed nucleophilic displacement of proline. The requirements for general acid catalysed expulsion of proline have interesting stereochemical consequences.