Formation of L-Glutamic Acid from γ-Aminobutyric Acid by Plant Enzyme

(1) From our view point, several investigations of the reverse action of L-glutamic acid decarboxylase occuring in plants were at-tempted, and the distribution and activity of L-glutamic acid decarboxylase in 50 kinds of edible plants were tested. During these experiments, severe inhibition of α-ketoglutaric acid was recognized, besides activation of the enzyme action by pyridoxal phosphate, and the occurrence of L-glutamic acid and γ-aminobutyric acid was always found in the same plant tissue. (2) From repeated experiments, it has been made clear that α-ketoglutaric-γ-aminobutyric transaminase may be demonstrated in the same plant tissue containing L-glutamic acid decarboxylyase, and finally we succeeded to confirm α-ketoglutaric-γ-aminobutyric trans-aminase in the L-glutamic acid decarboxylase as it is repbrted in many papers. (3) Moreover, it was confirmed that the dry plant α-ketoglutaric-γ-aminobutyric transaminase preparation obtained here catalyses the biosynthesis in vitro of L-glutamic acid from γ-aminobutyric acid in addition of α-ketoglutaric acid, at pH 7.4, while the same preparation may also activate the conversion of L-glutamic acid to γ-aminobutyric acid and CO2, at pH5.8.