Penicillin amidase fromAlcaligenes faecalisis a recently identifiedN-terminal nucleophilehydrolase,whichpossesses the highest specificity constant (kcat /Km)forthehydrolysis of benzylpenicillin compared with penicillin amidases from other sources. Similar to theEscherichia colipenicillin ami-dase, theA. faecalispenicillin amidase is maturatedin vivo from an inactive precursor into the catalytically active enzyme, containing one tightly bound Ca 2+ ion, via a complex post-translational autocatalytic processing with a multi-step excision of a small internal pro-peptide. .
