Sequential changes in amylase isozymes during grain maturation in barley

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Abstract
Changes in amylase isozyme patterns on polyacrylamide gels were followed during maturation in grains of Deba Abed barley. Early stage seeds contained a single, high-mobility enzyme (Band A) which had an estimated molecular weight of 4.2×104 and a high activity with β-limit dextrin as a substrate. It was shown, by dissection, that Band A was confined to the aleurone layer and probably represented the initial product of amylase synthesis. This form was succeeded, in mid-course, by a less mobile form (Band B), a β-amylase with a molecular weight of approximately 1.3×105. Late-dough stage grains contained a complex of low-mobility β-amylase bands which were shown, by papain digestion, to be protein-bound forms of Band B. The changes are discussed on the basis of a unified series consisting of elaborated forms of the initial Band A type of activity.