Novel penicillin G acylase from Achromobacter sp. CCM 4824

A novel penicillin G acylase from the bacterial strain Achromobacter sp. CCM 4824 was characterized. The specific activity of purified enzyme was 27.6 U mg−1 protein (6-nitro-3-phenylacetylamidobenzoic acid, NIPAB as the substrate). The enzyme consists of two dissimilar subunits α and β with a molecular mass of 27.0 and 62.4 kDa, respectively. The isoelectric point was about pH 8.8. The N-terminal amino acid sequence of β subunit (SNMWIVGRDHAKDARSILLN) and internal amino acid sequence of α subunit (YGYGYAVAQDRLFQMEMAR) exhibited a significant similarity with penicillin G acylases. The Km values for penicillin G and NIPAB were 1.9±0.1 and 4.5±0.2 μM, respectively. The turnover rates kcat for penicillin G and NIPAB were 29±1 and 19±1 s−1, respectively. The maximal hydrolytic activity of the enzyme was found at pH 7.5 and temperature of 60 °C. In contrast to the published substrate specificities of penicillin G acylases, the enzyme exhibited an almost two-fold hydrolytic activity with ampicillin, amoxicillin and cephalexin compared to penicillin G.