A, FITC-casein hydrolyzing proteinase activity of
extracts from 6- (○), 18- (•), and 30-month-old (▵) tubers. B,
Inhibition of the proteinase activity in extracts from 18- (•) and
30-month-old (▵) tubers with extracts from 6-month-old tubers. Data
are averages ± se of three replicates (se
values are eclipsed by the symbols in B). Inset shows immunoblots of
PMC (32 μg of protein per lane) in extracts from tubers, before and
after the addition of 6-month-old extract to extracts from 18- and
30-month-old tubers.