Are colorimetric assays appropriate for measuring phenol oxidase activity in peat soils?

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© 2016 The activity of extracellular phenol oxidases is believed to play a critical role in decomposition processes in peatlands. The water logged, acidic conditions, and recalcitrant litter from the peatland vegetation, lead to exceptionally high phenolics in the peat. In order to quantify the activity of oxidative enzymes involved in the modification and break down of phenolic compounds two types of assays are primarily utilized: L-DOPA and ABTS. This note focuses on the strengths and weaknesses of both approaches. Both assays involve a redox reaction and the resulting oxidized chromophore is measured spectrophotometrically. However, in the presence of reducing agents such as the phenolics commonly found in peat the colorimetric reaction is reversed and cannot be used to quantify phenol oxidase activity.

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Soil Biology and Biochemistry