作者:Ryan B. Pelto、R. F. Pratt
DOI:10.1021/bi101071r
日期:2010.12.14
O-(1-Carboxy-1-alkyloxycarbonyl) hydroxamates were found to spontaneously decarboxylate in aqueous neutral buffer to form O-(2-hydroxyalkylcarbonyl) hydroxamates, While the former molecules do not react rapidly with serine beta-lactamases, the latter are quite good substrates of representative class A and C, but not D, enzymes, and particularly of a class C enzyme. The enzymes catalyze hydrolysis of these compounds to a mixture of the alpha-hydroxy acid and hydroxamate. Analogous compounds containing aryloxy leaving groups rather that hydroxamates are also substrates. Structure-activity experiments showed that the alpha-hydroxyl group was required for any substantial substrate activity. Although both D- and L-alpha-hydroxy acid derivatives were substrates, the former were preferred. The response of the class C activity to pH and to alternative nucleophiles (methanol and D-phenylalanine) suggested that the same active site functional groups participated in catalysis as for classical substrates. Molecular modeling was employed to explore how the alpha-hydroxy group might interact with the class C beta-lactamase active site. Incorporation of the alpha-hydroxyalkyl moiety into novel inhibitors will be of considerable interest.