1989 Volume 42 Issue 10 Pages 1502-1505
Two different penicillins (p- and m-methylbenzylpenicillin) were obtained "in vitro" by direct enzymatic synthesis, using homogeneously pure acyl-CoA: 6-aminopenicillanic acid (6-APA) acyltransferase from Penicillium chrysogenum, 6-APA and p- or m-tolylacetyl-CoA. The Km for these substrates were 6 and 15mM, respectively, indicating that the affinity of the enzyme for these two molecules is much lower that shown by phenylacetyl-CoA (0.55 HIM). Furthermore, acyltransferase does not recognize o-tolylacetyl-CoA as a substrate suggesting that the position of the methyl group on the aromatic moiety may have a very important role in the formation of the enzyme-substrate complex.