当前位置： SCI文献检索 > BIOCHEMISTRY期刊下所有文献 > A New Covalent Inhibitor of Class C β-Lactamases Reveals Extended Active Site Specificity.

A New Covalent Inhibitor of Class C β-Lactamases Reveals Extended Active Site Specificity.

Abstract：

:O-Aryloxycarbonyl hydroxamates have previously been shown to efficiently inactivate class C β-lactamases by cross-linking serine and lysine residues in the active site. A new analogue of these inhibitors, D-(R)-O-(phenoxycarbonyl)-N-[(4-amino-4-carboxy-1-butyl)oxycarbonyl]hydroxylamine, designed to inactivate certain low-molecular mass dd-peptidases, has now been synthesized. Although the new molecule was found to be only a poor inactivator of the latter enzymes, it proved, unexpectedly, to be a very effective inactivator (ki = 3.5 × 10(4) M(-1) s(-1)) of class C β-lactamases, more so than the original lead compound, O-phenoxycarbonyl-N-(benzyloxycarbonyl)hydroxylamine. Furthermore, the mechanism of inactivation is different. Mass spectrometry demonstrated that β-lactamase inactivation by the new molecule involved formation of an O-alkoxycarbonylhydroxamate with the nucleophilic active site serine residue. This acyl-enzyme did not cyclize to cross-link the active site as did that from the lead compound. Model building suggested that the rapid enzyme acylation by the new molecule may occur because of favorable interaction between the polar terminus of its side chain and elements of the Ω loop that abuts the active site, Arg 204 in particular. This interaction should be considered in the design of new covalent β-lactamase inhibitors. The initially formed acyl-enzyme partitions (ratio of ∼ 1) between hydrolysis, which regenerates the active enzyme, and formation of an inert second acyl-enzyme. Structural modeling suggests that the latter intermediate arises from conformational movement of the acyl group away from the reaction center, probably enforced by the inflexibility of the acyl group. The new molecule is thus a mechanism-based inhibitor in which an inert complex is formed by noncovalent rearrangement. Phosphyl analogues of the new molecule were efficient inactivators of neither dd-peptidases nor β-lactamases.

journal_name

Biochemistry

journal_title

Biochemistry

authors

Tilvawala R,Cammarata M,Adediran SA,Brodbelt JS,Pratt RF

doi

10.1021/acs.biochem.5b01149

subject

Has Abstract

pub_date

2015-12-22 00:00:00

pages

7375-84

issue

eissn

0006-2960

issn

1520-4995

journal_volume

pub_type

杂志文章

在线工具

A New Covalent Inhibitor of Class C β-Lactamases Reveals Extended Active Site Specificity.