Enzymic degradiation of starch granules in the cotyledons of germinating peas.
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.
D000681:Amylases / Q000378:metabolism*; D000963:Antimetabolites / Q000494:pharmacology; D004586:Electrophoresis; D005964:Glucosyltransferases / Q000378:metabolism*; D007700:Kinetics; D010945:Plants, Edible / Q000201:enzymology; D012639:Seeds / Q000187:drug effects / Q000201:enzymology*; D013213:Starch / Q000378:metabolism*
D000963:Antimetabolites; D013213:Starch; D005964:Glucosyltransferases; D000681:Amylases