A study of the effect of particle-bound gamma-glutamyltranspeptidase on the product of interaction of fluoropyruvate with glutathione.

Fluoropyruvate has been shown to interact with thiol compounds (Avi-Dor & Mager, 1956a; Peters & Hall, 1957). Its inhibitory action on the respiration of mitochondria (Avi-Dor & Mager, 1956b; Chari-Bitron & Avi-Dor, 1958) and of tissue celLs (Traub & Ginzburg, 1959) is presumably due to combination with thiol groups. We have observed that, during an incubation of the product formed between glutathione and fluoropyruvate with a rat-kidney homogenate, glutamate is liberated. Concomitantly the extinction in the ultraviolet region increases greatly. The change in the spectrum allows the kinetics of the reaction to be followed in the spectrophotometer. It can be demonstrated that the enzyme responsible for the reaction is in the microsomal fraction. The pattern of the reaction of the microsome-bound enzyme suggests that it is identical with y-glutamyltranspeptidase, which is known to transfer the y-glutamyl moiety of glutathione to L-amino acids, or, in their absence, to water (for references see Revel & Ball, 1959).