Direct Evaluation of Phenylacetyl-Coa: 6-Aminopenicillanic Acid Acyltransferase of Penicillium Chrysogenum by Bioassay

Abstract

The enzyme phenylacetyl-CoA: 6-Aminopenicillanic acid acyltransferase of Penicillium chrysogenum was evaluated by direct bioassay against Micrococcus luteus ATCC 9341. The enzyme required dithiothreitol, was inactivated by 0.2 mM Hg2+ (100%), Zn2+ (80%), Cu2+ (60%), 1 mM N-ethylmaleimide (80%), and showed maximal catalytic activity at pH 8.4 and 20°C. The V50values for phenylacetyl-CoA and 6-aminopenicillanic acid were 0.55 mM and 1 μM, respectively. When octanoyl-CoA was employed as substrate similar results were obtained. In both cases the product generated showed strong antibacterial activity which was quickly lost when incubation was carried out with β-lactamase. Reactions performed in the presence of Escherichia coli penicillin acylase did not generated active products when phenylacetyl-CoA was the substrate; they did with octanoyl-CoA. Time-course experiments revealed that the highest enzyme levels are found in 36 hours mycelium and remained almost constant from 48 to 96 hours; thereafter the level of the enzyme slowly decreased. © 1986, JAPAN ANTIBIOTICS RESEARCH ASSOCIATION. All rights reserved.