Polyphenol oxidase characteristics

The phenol oxidases probably play no important role in the elimination of phenolic pressor amines, in spite of the importance that has been attached to the oxidation of the catechol nucleus in the past. The names phenolase and cresolase, polyphenol oxidase, and catechol oxidase serve to identify the enzyme with its mono- or diphenolic substrate, but they usually occur together and are difficultly separated. The enzymes have been purified and their characteristics have been described (56, 104, 106, 156). Beyer (21), Alles (5), and Randall and Hitchings (129) have described the relationship of structure of the phenolic pressor amines to the rate of oxidation of their nucleus in the presence of these enzymes. 

Park, E.B., Lee, J.S., and Choi, E.H., Isolation and characteristics of polyphenol oxidase from Jerusalem artichoke tuber, Han guk Sikp um Kwahakhoechi, 23, 414—419, 1991. 

Kim MK, Lee JS, Lee HG. Ascorbyl palmitate-loaded chitosan nanoparticles Characteristic and polyphenol oxidase inhibitory activity. Colloids Sirrf B Biointerfaces. 2012 103 391. ... 

Oxidations now known to be catalyzed by copper-containing enzymes were noticed over a century ago, when Schoenbein observed that oxidation of natural substrates resulted in pigment formation in mushrooms. Individual enzymes were gradually identified laccase by Yoshida in 1883 and tyrosinase by Bertrand in 1896. However, it was not imtil potato polyphenol oxidase was isolated in 1937 by Kubowitz that the role of copper was defined. The family of copper oxidases includes a number of enzymes of both plant and animal origin that may very probably be found to react through similar mechanisms, but which exhibit a number of individual characteristics. The enzymes to be described in this section include potato phenol oxidase, mushroom polyphenol oxidase (tyrosinase), laccase, mammalian and insect tyrosinase, and ascorbic acid oxidase. Each of these differs in certain respects from the others, and undoubtedly other related enzymes will be described from other sources that resemble these, but also display individualities. In these cases, identities in nomenclature must not be extended to imply identities in enzyme structure or activity. 

Taking Into account the behaviour of laccase towards carbon monoxide and the characteristic blue colour, one can discern Its close relationship with AAO. On the other hand, the nature of the substrate utilized by laccase entitled It to be classed as a close relative of polyphenol oxidase. Thus these three enzymes are closely related to one another ... 

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