The autoxidation of pyrogallol was investigated in the presence ofEDTA in the pH range7.9- 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, 02.-i,n the reaction. Up to pH 9.1 the reaction is still inhibited to over 90% by
superoxide dismutase, but at higher alkalinity, O,.--independent mechanisms rapidly become
dominant.
Catalase has no effect on the autoxidation but decreases the oxygen consumption by half,
showing that H202 is the stable product of oxygen and that H20, 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
0-methyltransferase brought about by pyrogallol.