The selective inhibition of ortho- and para-diphenol oxidases

Ortho- and para-diphenol oxidases (DPO's) are often distinguished by substrate specificity tests which are not always unequivocal. This paper suggests that they may be differentiated by their response patterns to certain inhibitors and activators. In general o-DPO's (‘catecholases’) are inhibited by substituted cinnamic acids (cinnamic, p-coumaric and ferulic), or polyvinylpyrrolidone (PVP) and may be activated by anionic detergents. By contrast p-DPO's (‘laccases’) are unaffected by cinnamic acids and PVP but are inhibited by cationic detergents such as cetyltrimethylammonium bromide (CTAB). Thus in crude extracts these enzymes may be clearly distinguished by a simple combination of substrate and inhibitor specificity tests.