Extracts of hulls from developingBrassica campestrisandBrassica napusseeds were examined for alpha;-amylase activity. The enzyme was compared with alpha;-amylase from barley pericarp and germinated barley seeds, using isoelectric focusing. Enzymes of similar isoelectric point (pI) were present inB.campestris,B.napus, and barley pericarp. Additional bands of activity were present inB.napus. The major alpha;-amylase component of germinated barley has a high pI, but no corresponding isozyme was detected in the other three samples. The increase in total activity of alpha;-amylase inBrassicaseed hulls coincided with the increase in starch granule size in the epidermal cell layer, with maximum activity approximately 16 days after pollination.
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