Enzymatic Hydrolysis of N-Acylated 1-Aminophosphonic Acids

Abstract

Abstract Penicillin acylase from E. coli (FC 3.5.1.11) was found to hydrolyse N-phenylacetylated 1-aminoalkylphosphonic acids and their esters. Enzyme preferentially converts the R-form of the substrates: the ratios of the bimolecular rate constants of penicillin acylase-catalysed hydrolysis of R-and S- forms of 1-(N-phenylacetaminol-ethylphosphonic acid and its dimethyl- and diisopropyl- esters are 58000, 2600, 1800; these derivatives were shown to have the greatest values of the catalytic constants for enzymatic hydrolysis of all known substrates of penicillin acylase: 237, 148, and 134 s; corresponding values of Michaelis constants are 3.7×10−5, 6.8×10−4, and 6.2×10−4 M. The kinetics of the enzymatic hydrolysis of 1-(N-phenylacetaminol-ethylphosphonic acid was investigated up to high degrees of conversion. The inhibition of penicillin acylase by high concentrations of the R-form of the substrate (with substrate inhibition constant 0.07 Ml and competitive inhibition by the reaction product phenylacetic acid (Ki=3.5×10−5 M) was observed. Penicillin acylase was shown to possess quite broad substrate specificity among N-acylated 1-aminoalkylphosphonic acids and was found to be capable of hydrolysing 1-(N-phenylacetaminol-substituted 2-phenylethyl-, 1-phenylmethyl- and 3-methylbutylphosphonic acids with high efficiency and enantioselectivity.