Abstract
Microsomes from both avocado mesocarps and tulip bulbs contained about six times more cytochrome P-450 than those of either potato tubers or cauliflower buds. The specific activity of trans-cinnamate 4-monooxygenase (EC 1.14.13.11) per P-450 in potato microsomes, however, was found to be 9 fold and 200 fold higher than avocado and tulip microsomes, respectively. Little activity of trans-cinnamate 4-monooxygenase was detected in microsomes of cauliflower buds, although the content of cytochrome P-450 in this tissue is comparable to potato tubers. On the other hand, trans-cinnamate 4-monooxygenase activity in Jerusalem artichoke tuber microsomes correlated with the increase of cytochrome P-450 after wounding of tuber tissues. Less heterogeneity of substrate specificity was observed among the microsomes from various plant tissues with exogenous compound, that is, benzphetamine. These results suggested the presence of multiple forms of cytochrome P-450 in plant microsomes and therefore the content of cytochrome P-450 and trans-cinnamate 4-monooxygenase activity was not proportional in a variety of plant tissues.
