Changes in the composition of proteins and free amino acids and the activities of enzymes responsible for the metabolism of glutamine and malate in germinating triticale seeds

摘要

Substantial qualitative and quantitative changes in the polypeptide composition of triticale germs were observed during early stages of seed germination (24 h). These data show that mobilization of reserve polypeptides occurs early during seed germination. Although the content of free amino acids sharply increased after 12 h of germination, the onset of noticeable mobilization of reserve proteins in the endosperm occurred much later. Studies of individual amino acids showed that the content of glutamic acid in both the embryo and endosperm increased after 18 h of germination and then decreased almost twofold after 72 h, whereas the content of glutamine decreased. The content of aspartic acid remained virtually unchanged in the endosperm but increased many times in the embryo. The activities of glutamine synthetase (EC 6.3.1.2) and glutaminase (EC 3.5.1.2) increased significantly, especially in the embryo. This finding can be regarded as evidence for the existence of the glutamine cycle.