Urate as a physiological substrate for myeloperoxidase: implications for hyperuricemia and inflammation.
J Biol Chem
; 286(15): 12901-11, 2011 Apr 15.
Article
em En
| MEDLINE
| ID: mdl-21266577
ABSTRACT
Urate and myeloperoxidase (MPO) are associated with adverse outcomes in cardiovascular disease. In this study, we assessed whether urate is a likely physiological substrate for MPO and if the products of their interaction have the potential to exacerbate inflammation. Urate was readily oxidized by MPO and hydrogen peroxide to 5-hydroxyisourate, which decayed to predominantly allantoin. The redox intermediates of MPO were reduced by urate with rate constants of 4.6 × 10(5) M(-1) s(-1) for compound I and 1.7 × 10(4) M(-1) s(-1) for compound II. Urate competed with chloride for oxidation by MPO and at hyperuricemic levels is expected to be a substantive substrate for the enzyme. Oxidation of urate promoted super-stoichiometric consumption of glutathione, which indicates that it is converted to a free radical intermediate. In combination with superoxide and hydrogen peroxide, MPO oxidized urate to a reactive hydroperoxide. This would form by addition of superoxide to the urate radical. Urate also enhanced MPO-dependent consumption of nitric oxide. In human plasma, stimulated neutrophils produced allantoin in a reaction dependent on the NADPH oxidase, MPO and superoxide. We propose that urate is a physiological substrate for MPO that is oxidized to the urate radical. The reactions of this radical with superoxide and nitric oxide provide a plausible link between urate and MPO in cardiovascular disease.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Superóxidos
/
Peroxidase
/
Hiperuricemia
/
Peróxido de Hidrogênio
/
Neutrófilos
Limite:
Humans
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
2011
Tipo de documento:
Article
País de afiliação:
Nova Zelândia