Abstract
Cyanoepithioalkane (GETA) -producing activity in seeds and seedlings of 22 varieties of cruciferous vegetables was studied using 3-butenylglucosinolate as a substrate. Also, the correlation of CETA-producing activity with the activity of myrosinase (thioglucoside glucohydrolase, EC 3, 2, 3, 1) was investigated along with the effects of pH and temperature on both activities. All plant materials examined had various levels of CETA-producing activity, of which higher levels were detected in seeds and 8-day-old seedlings of Brassica oleracea L., B. juncea Coss and Raphanus sativus L., and lower levels in those of B. campestris L. Although seeds and 4-day-old seedlings showed relatively higher coefficients of correlation between CETA-producing activity and myrosinase activity, the correlation was considerably low in the case of 8-day-old seedlings. The effects of pH and temperature on the two enzyme activities, which were assayed using an enzyme extract prepared from 4-day-old seedling of Ohba-Takana (B. juncea Coss), were different. The optimum pH and temperature for CETA-producing activity were pH 6.0 and 15-25°C, whereas those for myrosinase were pH 6.6-7.8 and 45-55°C, respectively.
