Approaches to the simultaneous inactivation of metallo- and serine-beta-lactamases.
A series of cephalosporin-derived reverse hydroxamates and oximes were prepared and evaluated as inhibitors of representative metallo- and serine-beta-lactamases. The reverse hydroxamates showed submicromolar inhibition of the GIM-1 metallo-beta-lactamase. With respect to interactions with the classes A, C, and D serine beta-lactamases, as judged by their correspondingly low K(m) values, the reverse hydroxamates were recognized in a manner similar to the non-hydroxylated N-H amide side chains of the natural substrates of these enzymes. This indicates that, with respect to recognition in the active site of the serine beta-lactamases, the OC-NR-OH functionality can function as a structural isostere of the OC-NR-H group, with the N-O-H group presumably replacing the amide N-H group as a hydrogen bond donor to the appropriate backbone carbonyl oxygen of the protein. The reverse hydroxamates, however, displayed k(cat) values up to three orders of magnitude lower than the natural substrates, thus indicating substantial slowing of the hydrolytic action of these serine beta-lactamases. Although the degree of inactivation is not yet enough to be clinically useful, these initial results are promising. The substitution of the amide N-H bond by N-OH may represent a useful strategy for the inhibition of other serine hydrolases.
Ganta
Sudhakar Reddy
SR
Department of Chemistry, Southern Methodist University, Dallas TX 75275-0314, United States.
Perumal
Senthil
S
Pagadala
Sundar Ram Reddy
SR
Samuelsen
Orjan
O
Spencer
James
J
Pratt
R F
RF
Buynak
John D
JD
D000577:Amides / Q000737:chemistry; D020816:Amino Acid Motifs; D020134:Catalytic Domain; D002511:Cephalosporins / Q000138:chemical synthesis* / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000494:pharmacology; D006877:Hydroxamic Acids / Q000737:chemistry; D020128:Inhibitory Concentration 50; D007700:Kinetics; D008670:Metals / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D010091:Oximes / Q000737:chemistry; D012694:Serine / Q000737:chemistry*; D001618:beta-Lactamases / Q000737:chemistry*
D000577:Amides; D002511:Cephalosporins; D004791:Enzyme Inhibitors; D006877:Hydroxamic Acids; D008670:Metals; D010091:Oximes; D012694:Serine; D001618:beta-Lactamases