gamma-Glutamyl transpeptidase activity can be altered by kainic acid and related compounds

The effect of kainic acid and related compounds, gamma-D-glutamylglycine, cis-2,3-piperidine dicarboxylic acid and DL alpha-aminoadipic acid, was investigated on purified and membrane bound gamma-glutamyl transpeptidase [GGT]. All four compounds suppressed enzyme activity to an extent which depended upon the presence of a gamma-glutamyl moiety acceptor. Of the amino acid and dipeptide acceptors used, glycyl-glycine was the most affected. These compounds may be useful probes in determining the physiological role of gamma-glutamyl transpeptidase. The relationship between GGT, the gamma-glutamyl cycle and the toxicity of kainic acid is discussed.