Substrate specificity of penicillin acylase of E. coli

The hydrolysis of several phenylacetylamino compounds was studied using a purified preparation of E. coli penicillin acylase. The L-isomers of phenylacetyl amino acids were cleaved much faster than the D-isomers. The same observations was made for some phenylacetylamino beta-lactams. When the beta-lactam ring is incorporated in a penam or cephem ring system, the D-isomers were hydrolysed somewhat faster than the L-isomers. We also confirmed that benzylpenicillins with an hydroxy- or an amino-group in alpha-position of the side chain were hydrolysed, both in the normal and the 6-epi-series.