Glutathione S-transferases catalyzed conjugation of 1,4-disubstituted butanes with glutathione in vitro.

Rat liver glutathione S-transferases catalyzed the conjugation of 1,4-diiodobutane with glutathione in vitro. The reaction followed saturation kinetics and was dependent on the concentration of the enzyme, substrate and glutathione in the incubation media. S-Benzylglutathione inhibited the enzymatic conversion of 1,4-diiodobutane to product. The cyclic sulfonium compound, gamma-glutamyl-beta-(S-tetrahydrothiophenium) alanyl-glycine was identified as the product of this conjugation reaction. This product was stable under physiological conditions in presence of rat liver cytosol but rapidly and quantitatively decomposed at pH greater than or equal to 12 to give tetrahydrothiophene.