A kinetic analysis of the inhibition of FOX-4 ß-lactamase, a plasmid-mediated AmpC cephalosporinase, by monocyclic ß-lactams and carbapenems.
J Antimicrob Chemother
; 69(3): 682-90, 2014 Mar.
Article
em En
| MEDLINE
| ID: mdl-24235094
ABSTRACT
OBJECTIVES:
Class C ß-lactamases are prevalent among Enterobacteriaceae; however, these enzymes are resistant to inactivation by commercially available ß-lactamase inhibitors. In order to find novel scaffolds to inhibit class C ß-lactamases, the comparative efficacy of monocyclic ß-lactam antibiotics (aztreonam and the siderophore monosulfactam BAL30072), the bridged monobactam ß-lactamase inhibitor BAL29880, and carbapenems (imipenem, meropenem, doripenem and ertapenem) were tested in kinetic assays against FOX-4, a plasmid-mediated class C ß-lactamase (pmAmpC).METHODS:
The FOX-4 ß-lactamase was purified. Steady-state kinetics, electrospray ionization mass spectrometry (ESI-MS) and ultraviolet difference (UVD) spectroscopy were conducted using the ß-lactam scaffolds described.RESULTS:
The K(i) values for the monocyclic ß-lactams against FOX-4 ß-lactamase were 0.04 ± 0.01 µM (aztreonam) and 0.66 ± 0.03 µM (BAL30072), and the Ki value for the bridged monobactam BAL29880 was 8.9 ± 0.5 µM. For carbapenems, the Ki values ranged from 0.27 ± 0.05 µM (ertapenem) to 2.3 ± 0.3 µM (imipenem). ESI-MS demonstrated the formation of stable covalent adducts when the monocyclic ß-lactams and carbapenems were reacted with FOX-4 ß-lactamase. UVD spectroscopy suggested the appearance of different chromophoric intermediates.CONCLUSIONS:
Monocyclic ß-lactam and carbapenem antibiotics are effective mechanism-based inhibitors of FOX-4 ß-lactamase, a clinically important pmAmpC, and provide stimulus for the development of new inhibitors to inactivate plasmidic and chromosomal class C ß-lactamases.Palavras-chave
Texto completo:
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Carbapenêmicos
/
Proteínas de Escherichia coli
/
Beta-Lactamas
/
Inibidores Enzimáticos
Idioma:
En
Revista:
J Antimicrob Chemother
Ano de publicação:
2014
Tipo de documento:
Article