gamma-Glutamyltransferase activity was studied in extracts of the cnidarian Hydra attenuata. The binding of gamma-glutamyl peptide analogues to the enzyme was studied by observing their effects on heat denaturation and their inhibition of p-nitroaniline release from gamma-glutamyl p-nitroanilide. Neither position-1 analogues, in which the gamma-glutamyl moiety was changed to a beta-aspartyl (beta-Asp-Abu-Gly) or an alpha-glutamyl (Glu-Abu-Gly) linkage, nor glutamate protected the enzyme against inactivation at 58 degrees C. GSH (reduced glutathione), gamma-Glu-Abu-Gly and gamma-Glu-Met on the other hand did prevent heat denaturation. GSH and analogues of GSH were competitive inhibitors of p-nitroaniline release, but those analogues in which glycine was replaced by 2-aminoisobutyrate, phenylalanine, leucine or tyrosine had Ki values that were approximately five times those of analogues with the cysteine residue replaced.
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Research Article| November 01 1978
Interaction of glutathione analogues with Hydra attenuata γ-glutamyltransferase
Biochem J (1978) 175 (2): 547–553.
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J Danner, M H Cobb, W Heagy, H M Lenhoff, G R Marshall; Interaction of glutathione analogues with Hydra attenuata γ-glutamyltransferase. Biochem J 1 November 1978; 175 (2): 547–553. doi: https://doi.org/10.1042/bj1750547
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