Ap. Laws et al., THE MECHANISM OF REACTIONS CATALYZED BY THE SERINE BETA-LACTAMASES, Bioorganic & medicinal chemistry letters, 3(11), 1993, pp. 2317-2322
Nucleophilic substitution at the beta-lactam carbonyl of penicillins u
sually requires general base and acid catalysis and proceeds via the f
ormation of a tetrahedral intermediate. A class C serine beta-lactamas
e is inhibited by phosphonamidates, shows diastereoselectivity in P-N
and P-0 bond fission and exhibits enzyme catalysed nucleophilic displa
cement of proline. The requirements for general acid catalysed expulsi
on of proline have interesting stereochemical consequences.