Geração de oxigenio singlete durante a oxidação de acido folico catalizada por peroxidases

AUTOR(ES)
DATA DE PUBLICAÇÃO

1981

RESUMO

An extracted protein from red blood cells catalyses the transformation of falic acid to produce pterin-6-aldeyde an p-aminobenzoylglutamic acid when hydrogen peroxide is present. Horseradish peroxidase catalyses folic acid as well to produce the same products when glutathione and Mn are presents, but in this case hydrogen peroxide seems to be prejudicial to the reaction. The photoemission that accompanies the metabolism of folic acid by both enzymes, evidences the formation of an intermediate in excited state. Studies of this metabolism with singlet oxigen quenchers as bilirubin; enhancers of singlet oxygen emission as 1.4-diazo-bicyclo(2.2.2)octane (DABCO); the system behaviour toward D2O, as well as the unefficiency of the anthracenic acceptors on the photoemission, suggest that singlet oxygen is responsable by that emission. Bilirubin quenches the emission from the enzymatic system initially by reacting with singlet oxygen to produce presumably a 1,2-dioxetane intermediate, which cleaves to ketone fragments in excited states as proved by the enhanced emission with DBAS, an excellent triplet ketone counter.

ASSUNTO(S)

oxidação fisiologica oxigenio

ACESSO AO ARTIGO

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