Alexey Bulychev

N-Sulfonyloxy-β-lactam Inhibitors for β-Lactamases

Abstract Structure-function analysis with a series of N-sulfonyloxy β-lactam molecules as inhibitors of β-lactamases is reported. The best of these compounds acylate the active site of the class A TEM-1 β-lactamase from Escherichia coli rapidly, and resist deacylation. Whereas acylation of the active site of the class C β-lactamase from Enterobacter cloacae was not seen, these compounds function as competitive inhibitors of this enzyme.

Inhibition of the broad spectrum nonmetallocarbapenamase of class A (NMC-A) beta-lactamase from Enterobacter cloacae by monocyclic beta-lactams.

β-Lactamases hydrolyze β-lactam antibiotics, a reaction that destroys their antibacterial activity. These enzymes, of which four classes are known, are the primary cause of resistance to β-lactam antibiotics. The class A β-lactamases form the largest group. A novel class A β-lactamase, named the nonmetallocarbapenamase of class A (NMC-A) β-lactamase, has been discovered recently that has a broad substrate profile that included carbapenem antibiotics. This is a serious development, since carbapenems have been relatively immune to the action of these resistance enzymes. Inhibitors for this enzyme are sought. We describe herein that a type of monobactam molecule of our design inactivates the NMC-A β-lactamase rapidly, efficiently, and irreversibly. The mechanism of inactivation was investigated by solving the x-ray structure of the inhibited NMC-A enzyme to 1.95 Å resolution. The structure shed light on the nature of the fragmentation of the inhibitor on enzyme acylation and indicated that there are two acyl-enzyme species that account for enzyme inhibition. Each of these inhibited enzyme species is trapped in a distinct local energy minimum that does not predispose the inhibitor species for deacylation, accounting for the irreversible mode of enzyme inhibition. Molecular dynamics simulations provided evidence in favor of a dynamic motion for the acyl-enzyme species, which samples a considerable conformational space prior to the entrapment of the two stable acyl-enzyme species in the local energy minima. A discussion of the likelihood of such dynamic motion for turnover of substrates during the normal catalytic processes of the enzyme is presented.

Templates for design of inhibitors for serine proteases: Application of the program dock to the discovery of novel inhibitors for thrombin

The program DOCK was used to search for novel inhibitors for alpha-thrombin. Four among the top twelve best scoring compounds from the Cambridge Structural Data Base inhibited this enzyme, and three of them inhibited alpha-thrombin in a competitive mode. These molecules are expected to serve as general templates for structural elaboration in targeting diverse serine proteases for selective inhibition.