Inhibition of Stenotrophomonas maltophilia dihydrofolate reductase by methotrexate: A single slow-binding process
Source: Journal of Enzyme Inhibition and Medicinal Chemistry, Volume 22, Number 4, August 2007 , pp. 377-382(6)
Publisher: Informa Healthcare
Abstract:Although antifolates such as trimethoprim are used in the clinical treatment of Stenotrophomonas maltophilia infection, the dihydrofolate reductase (DHFR) of this microorganism is scarcely known because it has never been isolated. Here, we describe the purification of this enzyme and kinetically characterize its inhibition by methotrexate (MTX). Upon MTX treatment, time-dependent, slow-binding inhibition was observed due to the generation of a long-lived, slowly dissociating enzyme-NADPH-inhibitor complex. Kinetic analysis revealed a one-step inhibition mechanism [image omitted] with an association rate constant (ki) of 3.8 × 107 M- 1s- 1. Possible mechanisms for MTX binding to S. maltophilia DHFR are discussed.
Document Type: Research Article
Affiliations: 1: Grupo de Investigación de Enzimología, Departamento de Bioquímica y Biología Molecular A, Facultad de Biología, Universidad de Murcia, Espinardo, Murcia, Spain 2: Servicio de Análisis Clínicos, Hospital, Universitario Virgen de la Arrixaca, Murcia, Spain
Publication date: August 1, 2007