Open AccessInvolvement of the Superoxide Anion Radical in the Autoxidation of Pyrogallol and a Convenient Assay for Superoxide Dismutase
Author(s) -
MARKLUND Stefan,
MARKLUND Gudrun
Publication year - 1974
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1974.tb03714.x
Subject(s) - autoxidation , pyrogallol , chemistry , superoxide dismutase , superoxide , catechol , catalase , homolysis , oxygen , medicinal chemistry , radical , enzyme , photochemistry , nuclear chemistry , biochemistry , organic chemistry
The autoxidation of pyrogallol was investigated in the presence of EDTA in the pH range 7.9–10.6. The rate of autoxidation increases with increasing pH. At pH 7.9 the reaction is inhibited to 99% by superoxide dismutase, indicating an almost total dependence on the participation of the superoxide anion radical, O 2 · − , in the reaction. Up to pH 9.1 the reaction is still inhibited to over 90% by superoxide dismutase, but at higher alkalinity, O 2 · − ‐independent mechanisms rapidly become dominant. Catalase has no effect on the autoxidation but decreases the oxygen consumption by half, showing that H 2 O 2 is the stable product of oxygen and that H 2 O 2 is not involved in the autoxidation mechanism. A simple and rapid method for the assay of superoxide dismutase is described, based on the ability of the enzyme to inhibit the autoxidation of pyrogallol. A plausible explanation is given for the non‐competitive part of the inhibition of catechol O ‐methyltransferase brought about by pyrogallol.