It is responsible for browning reactions throughout the phylogenetic scale. Bouchilloux et al . The amino acid composition has been determined. Extensive structural studies have been reported by Jolley et al . See also Jolley et al .
Polyphenol oxidase is an oxygen transferring enzyme.
The lyophilized preparation is stable for 6-12 months when stored at 5deg. Polyphenol oxidase oxidizes tyrosine to dihydroxyphenylalanine which in turn is oxidized to o-quinone. The latter is accompanied by an increase in absorbance at 280 nm. The rate of increase is proportional to enzyme concentration and linear during a period of 5-10 minutes after an initial lag. One unit causes a change in absorbance at 280 nm of 0.001 per minute at 25deg.