Transaminase, amylase and protease activities were compared in seedlings of normal and Opaque-2 (o2) maize. Transaminase activity, greater in normal maize, was highest in the scutellum from which it decreased rapidly in activity from day 2 after imbibition; only low activity was observed in endosperm and axis tissue.Amylolytic activity, optimal around pH 5, was greater in normal maize at all stages of endosperm degradation. Activity which was low on day 2, rose to a peak on day 6 and declined afterwards. The level of free sugars in the endosperm of normal was higher than in o2 maize, and in both varieties was highly correlated with amylolysis.Protease activity, optimal at pH 3.6, was also greater in normal endosperms and increased up to day 6 and activity was maintained at this level until around day 14. Although the activity of all three enzyme systems examined was greater in normal maize there were no apparent differences in the overall growth of normal and o2 seedlings during this period. © 1983 Annals of Botany Company.524535541