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  • Title: Enzymic degradiation of starch granules in the cotyledons of germinating peas.
    Author: Juliano BO, Varner JE.
    Journal: Plant Physiol; 1969 Jun; 44(6):886-92. PubMed ID: 5799049.
    Abstract:
    Starch, total alpha- and beta-amylase, and phosphorylase levels and the zymogram patterns of these 3 starch-degrading enzymes were determined in the cotyledons of smooth pea (Pisum sativum L.) during the first 15 days of germination. Starch is degraded slowly in the first 6 days; during this time, alpha-amylase is very low, beta-amylase is present at a constant level while phosphorylase gradually increases and reaches a peak on the fifth day. Beginning on the sixth day there is a more rapid degradation of starch which coincides with alpha-amylase production. One phosphorylase band and 2 beta-amylase bands are present in the zymogram of the imbibed cotyledon. An additional phosphorylase band and 1 alpha-amylase band appear during germination. Seeds imbibed in benzyladenine, chloramphenicol, and in cycloheximide show retarded growth and slower starch degradation and enzyme production than the controls. We conclude that alpha-amylase is the major enzyme involved in the initial degradation of starch into more soluble forms while phosphorylase and beta-amylase assist in the further conversion to free sugars.
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