γ-Glutamyl transpeptidase (EC 22.214.171.124) activity is described in the coelenterate, Hydra attenuata, using the substrate γ-glutamyl-p-nitroanilide. The properties of the γ-glutamyl donor required for binding to the transpeptidase were investigated by measuring the ability of GSH analogs to inhibit the release of p-nitroaniline. Whereas no binding was observed when the γ-glutamyl moiety was altered, analogs with substitution in the Cys residue were capable of binding to the enzyme. A specificity for the Gly residue was indicated because analogs containing Leu or Tyr in place of Gly exhibited decreased binding capacities for the hydra transpeptidase. A comparison of these data with those obtained using the same analogs in the GSH induced feeding response bioassay shows that γ-glutamyl transpeptidase activity and the GSH receptor for the hydra feeding response have different specificities.
|Original language||English (US)|
|Number of pages||7|
|Journal||Biochemical and Biophysical Research Communications|
|State||Published - Nov 8 1976|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology