Catechol Oxidase in Tissue 4

Catechol oxidase activity in tissue culture of apple fruit wasfollowed during growth. Enzyme activity was not found to becorrelated with the growth of the cultures. Cnltures with initiallyhigh enzyme activity show a lag in growth while enzyme activitydeclines. In cultures with an initial low activity, rapid growthis followed by an increase in enzyme activity which declinesagain as growth slows down. As the tissue ages, a greater proportionof enzyme activity is found in the soluble part of the cell. Low concentrations of O₂, lowered sucrose concentrations, orraised NaCl concentrations in the medium depress growth of theculture rapidly, while their effect on enzyme activity is delayed. Rapid desiccation of the tissue causes a large increase in enzymeactivity, possibly by activation, within 20 h. The subcollulardistribution of enzyme is changed at the same time.