Catechol Oxidase versus Tyrosinase Classification Revisited by Site‐Directed Mutagenesis Studies

Catechol oxidases (COs) and tyrosinases (TYRs) are both polyphenol oxidases (PPOs) that catalyze the oxidation of ortho ‐diphenols to the corresponding quinones. By the official classification, only TYRs can also catalyze the hydroxylation of monophenols to ortho ‐diphenols. Researchers have been trying to find the molecular reason for the mono‐/diphenolase specificity for decades. However, the hypotheses for the lack of monophenolase activity...