ENZYMATIC DEGRADATION OF PHENOLIC MATERIALS IN PEATLANDS - MEASUREMENT OF PHENOL OXIDASE ACTIVITY

The model substrate L-dihydroxy phenylalanine (L-DOPA) was used to measure the activity of phenol-oxidase (PO) in peat from a Welsh riparian wetland. The sensitive and relatively simple technique measured the rate of formation of the red coloured compound 2-carboxy-2,3-dihydroindole-5,6-quinone from the enzymic oxidation of L-dopa. The method was used to test the hypothesis that the large exports of phenolic materials from peatlands into aquatic systems were caused by low phenolic-degrading enzyme activities within the peat matrix. The low oxygen availability and acidic pH of the peat soil were found to be sub-optimal for PO activity. Furthermore, a depth-dependent decline in PO activity was inversely correlated with phenolic concentrations. Thus, the findings supported the above hypothesis.