Affiliation:
1. Novexel SA, Parc Biocitech, 102 Avenue Gaston Roussel, 93230 Romainville, France
2. CIP/Enzymology, Université de Liège, Institute of Chemistry B6, Sart-Tilman B4000 Liège, Belgium
Abstract
ABSTRACT
NXL104 is a potent inhibitor of class A and C serine β-lactamases, including KPC carbapenemases. Native and NXL104-inhibited TEM-1 and P99 β-lactamases analyzed by liquid chromatography-electrospray ionization-time of flight mass spectrometry revealed that the inactivated enzymes formed a covalent adduct with NXL104. The principal inhibitory characteristics of NXL104 against TEM-1 and P99 β-lactamases were determined, including partition ratios, dissociation constants (
K
), rate constants for deactivation (
k
2
), and reactivation rates. NXL104 is a potent inhibitor of TEM-1 and P99, characterized by high carbamylation efficiencies (
k
2
/
K
of 3.7 × 10
5
M
−1
s
−1
for TEM-1 and 1 × 10
4
M
−1
s
−1
for P99) and slow decarbamylation. Complete loss of β-lactamase activity was obtained at a 1/1 enzyme/NXL104 ratio, with a
k
3
value (rate constant for formation of product and free enzyme) close to zero for TEM-1 and P99. Fifty percent inhibitory concentrations (IC
50
s) were evaluated on selected β-lactamases, and NXL104 was shown to be a very potent inhibitor of class A and C β-lactamases. IC
50
s obtained with NXL104 (from 3 nM to 170 nM) were globally comparable on the β-lactamases CTX-M-15 and SHV-4 with those obtained with the comparators (clavulanate, tazobactam, and sulbactam) but were far lower on TEM-1, KPC-2, P99, and AmpC than those of the comparators. In-depth studies on TEM-1 and P99 demonstrated that NXL104 had a comparable or better affinity and inactivation rate than clavulanate and tazobactam and in all cases an improved stability of the covalent enzyme/inhibitor complex.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology
Cited by
130 articles.
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