The Enzymic Decarboxylation ofγ-methyleneglutamic Acid by Plant Extracts

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Abstract
γ-Methyleneglutamic acid, an acidic amino-acid isolated from groundnut plants, was decarboxylated by enzymes present in extracts of Capsicum fruits, barley roots, and tulip leaves, and also by intact cells of Clostridium welchii S.R. I2. The amino-acid was attacked in a similar manner to, but in all cases at a slower rate than, l-glutamic acid. The nature of the enzyme responsible for the decarboxylation of γ-methyleneglutamic acid was further investigated using preparations from barley roots (which do not contain the amino-acid) and from tulip leaves (in which the amino-acid is normally present, together with larger amounts of its amide form, γ-methyleneglutamine). The effects of pH, inhibitors, and partial heat denaturation upon the enzyme systems present in the barley and tulip extracts indicated that a single enzyme was responsible for the decarboxylation of both l-glutamic acid and γ-methyleneglutamic acid. Although the Cl. welchii rapidly deamidated and then decarboxylated l-glutamine, γ-methyleneglutamine was not attacked by the organism.