title: Degradation of penicillin G to phenylacetylglycine by D-alanine carboxypeptidase from Bacillus stearothermophilus.
abstract: D-Alanine carboxypeptidase from Bacillus stearothermophilus is a membrane-bound enzyme which is inhibited by covalent interaction with penicillin G. The penicilloyl enzyme spontaneously reactivates and simultaneously releases a penicillin G degradation product; 0.2 mumol of the latter was isolated after incubation of 4.2 mumol of [8-14C]penicillin G with 10 g of membrane protein. It was identified as phenylacetylglycine by chromatographic techniques, infrared spectroscopy, and mass spectrometry. A mechanism for the degradation is proposed in which the remaining part of penicillin G would be released as 5,5-dimethyl-delta2-thiazoline-4-carboxylic acid. The implications of this finding are discussed.
mesh_terms: D000409:Alanine; D002268:Carboxypeptidases / Q000378:metabolism*; D001411:Geobacillus stearothermophilus / Q000201:enzymology*; D008954:Models, Biological; D010400:Penicillin G / Q000378:metabolism*
chemical_list: D002268:Carboxypeptidases; D000409:Alanine; D010400:Penicillin G