Stimulation of glutathione degradation by amino acids: lack of stereospecificity

The rate of degradation of glutathione by rat kidney slices has been analysed. In the absence of exogenous amino acids a half-life of 84 min is found. In the presence of the L-isomer of three amino acids which are good substrates for gamma-glutamyl transpeptidase the rate of degradation is increased in a concentration-dependent manner. The stimulatory effect is not stereospecific, the D-isomers having a similar effect to their L-enantiomers. These findings indicate that perturbations in glutathione metabolism need not be due to the stimulation of active transport mediated by gamma-glutamyl transpeptidase.