Inverse acyl phosph(on)ates: Substrates or inhibitors of beta-lactam-recognizing enzymes?

Acyl phosph(on)ates represent a new class of inhibitors of beta -lactam-rec ognizing enzymes. Previously described members of this class were aroyl pho sph(on)ates. These compounds have been shown to acylate and/or phosphylate the active site serine residue, leading to either transient or essentially irreversible inhibition [Li, N., and Pratt, R. F. (1998) J. Am. Chem. Soc. 120, 4264-4268]. The present paper describes the synthesis and evaluation a s inhibitors of an inverse pair of acyl phosph(on)ates that incorporate the amido side chain that represents a major substrate specificity determinant of these enzymes. Thus, N-(phenylacetyl)glycyl phenyl phosphate and benzoy l N-(benzyloxycarbonyl)aminomethyl phosphonate were prepared. The former of these compounds was found to be a substrate of typical class A and C beta -lactamases and of the DD-peptidase of Streptomyces R61; it thus acylates t he active site serine. In contrast, the latter compound was an irreversible inhibitor of the above enzymes, probably by phosphorylation of the active site serine. With each of these enzymes therefore, the amido side chain rat her than the acyl group dictates the orientation of the bound phosph(on)ate and thus the mode of reaction. (C) 2001 Academic Press.