Myrosinase in Brassicaceae (Cruciferae): II. MYROSINASE ACTIVITY IN DIFFERENT ORGANS OF SINAPIS ALBA L.

Seeds of Sinapis alba L. were germinated in darkness for 3 dand a part of the etiolated seedlings were transferred to long-dayconditions for 6 weeks. Myrosinase solutions were prepared forcotyledons, hypocotyls, primary roots, leaves, stems, inflorescences,and seeds, and used to hydrolyse sinigrin. Glucose, one of the cleavage products, was determined by fourdifferent spectrophotometric methods, and their usefulness forcalculations of myrosinase activity in crude plant extractsis considered. Specific activity was calculated in relations to protein, andit was found to be about 30% higher in seedlings and also higherin seeds than in adult plants. Of the organs, those with thehighest activity were the hypocotyls and the stems. The differentparts of the plant contained different numbers of isoenzymes,as shown by polyacrylamide gel electrophoresis. Seedlings yieldedtwo, and adult plants four or five isoenzymes.