[Heterogeneity of molecular forms of phenol oxidase from apple fruits]

Qualitative differences of a dimer (m.w. 60.000-70.000) and a monomer (m.w. 30.000-40.000) fractions of phenoloxidase (EC 1.10.3.1), isolated from fruits of two winter varieties of apples were studied. tthe fractions analysed differed markedly in their Km values and the Hill coefficients. The monomer fraction possessed a higher affinity for monophenols and is capable to accomplish the hydroxylation reaction more actively. The interrelation of these changes and the aging of fruits under storage conditions with resulting changes in their total metabolism is discussed.