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Articles

Induction of -Amylase in Barley Endosperm by Substrate Levels of Glutamate and Aspartate ¹

^a Department of Biological Sciences, Northwestern University, Evanston, Illinois 60201

Incubation of embryoless barley (Hordeum vulgare) half-seeds for 24 hours with 0.1 M glutamate or aspartate resulted in the release of 17 to 48% as much -amylase as did incubation with 260 mµM gibberellin. With incubation periods of 48 to 51 hours these amino acids were on the average about half as active as response-saturating concentrations of gibberellin, and in some experiments they were essentially as active. Citric acid cycle intermediates, glycolytic pathway intermediates, and cofactors of these pathways failed to induce -amylase synthesis, while the following compounds were active: asparagine, homoserine, diaminopimelate, isoleucine, methionine, glutamine, ornithine, citrulline, argininosuccinate, and -aminolevulinate. However, threonine, lysine, -alanine, alanine, -aminobutyrate, -ketobutyrate, proline, arginine, glycine, leucine, and putrescine were inactive. Two patterns were noted in the list of active and inactive compounds: (a) all of the active compounds contain an amino group and are biosynthetically derived from citric acid cycle intermediates; and (b) biosynthetic precursors of the amino acids arginine, proline, threonine, and lysine were active whereas these amino acids were not.

¹ This investigation was supported by United States Public Health Service Research Grant CA-05387 from the National Cancer Institute and by National Science Foundation Grant GU-3320.