4-Fluoro-3-nitrophenyl azide, a selective photoaffinity label for type B monoamine oxidase.
Biochem Pharmacol
; 34(6): 781-8, 1985 Mar 15.
Article
em En
| MEDLINE
| ID: mdl-3977955
ABSTRACT
The effects of 4-fluoro-3-nitrophenyl azide (FNPA) on types A and B monoamine oxidase in rat brain cortex were studied using serotonin and phenylethylamine as substrates respectively. FNPA competitively inhibited the oxidative deamination of both serotonin (Ki = 3 microM) and phenylethylamine (Ki = 0.78 microM) in the dark. Upon photoirradiation in the presence of FNPA, a photodependent inhibition of type B MAO activity resulted. This photodependent inhibition was apparently irreversible since there was no recovery of activity upon washing of the photolyzed FNPA-enzyme mixture. Additional evidence for the photoinduced covalent binding of FNPA to type B MAO is that non-competitive inhibition kinetics resulted after photolysis. The specificity of the photodependent incorporation of FNPA to type B MAO was shown by the protective effect of phenylethylamine and by decreased [3H]pargyline labeling after the enzyme was photolyzed with FNPA. Under the same experimental conditions, only minimal photodependent inhibition of type A MAO by FNPA was found. The observed difference in the efficiencies of the photodependent inactivation of the two types of MAO by FNPA suggests that there is a conformational or a structural difference in the active sites of the two types of MAO. The active site of type B MAO could be characterized by utilizing FNPA as a photoaffinity labeling probe.
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Base de dados:
MEDLINE
Assunto principal:
Azidas
/
Marcadores de Afinidade
/
Monoaminoxidase
/
Inibidores da Monoaminoxidase
Limite:
Animals
Idioma:
En
Revista:
Biochem Pharmacol
Ano de publicação:
1985
Tipo de documento:
Article