Relaxed thiol substrate specificity of glutathione transferase effected by a non-substrate glutathione derivative.
Rat glutathione transferase 4-4 catalyzed the conjugation of 2-mercaptoethanol with 1-chloro-2,4-dinitrobenzene in the presence of S-methyl-glutathione. The reaction was linearly dependent on enzyme concentration and saturation was seen with respect to both 2-mercaptoethanol and S-methyl-glutathione concentration. High concentrations of S-methyl-glutathione were inhibitory. The results suggest that the natural substrate glutathione has two distinct functions in the normal catalytic reaction, (i) induction of a catalytically competent conformation of the enzyme and (ii) provision of the substrate sulfhydryl group in the reaction catalyzed.
Principato
G B
GB
Department of Biochemistry, University of Stockholm, Sweden.
Danielson
U H
UH
Mannervik
B
B
D000818:Animals; D004137:Dinitrochlorobenzene / Q000494:pharmacology; D005978:Glutathione / Q000031:analogs & derivatives* / Q000494:pharmacology; D005982:Glutathione Transferase / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008623:Mercaptoethanol / Q000378:metabolism; D051381:Rats; D013379:Substrate Specificity
D004137:Dinitrochlorobenzene; D008623:Mercaptoethanol; D005982:Glutathione Transferase; D005978:Glutathione; C017514:S-methyl glutathione