ON THE USE OF 2,4,5-TRIHYDROXYPHENETHYLAMINE AS PEROXIDASE SUBSTRATE

The rate of autoxidation of 2,4,5-trihydroxyphenethylamine (6-hydroxyd opamine) and the sensitivity of this autoxidation to increase by perox idases was studied. The autoxidation of 6-hydroxydopamine proceeds by a free radical chain reaction involving O-2 and produces the correspon ding chromogen 6-hydroxydopaminequinone and hydrogen peroxide. The yie ld of quinone produced increased with increasing pH in the range 5 --> 9. The ability of peroxidases to increase the autoxidation of 6-hydro xydopamine at pH 5.5 has been used as sensitive assay for these enzyme s. The results are tabulated and discussed.