S-Methylglutathione is an S-substitued glutathione and a stronger nucleophile than GSH[1]. S-Methylglutathione has inhibitory effect on glyoxalase 1[2].
S-Methylglutathione (GS-Me) is a stronger nucleophile than GSH, which is rationalized by the more positive inductive effect of the methyl group[1].
[1]. Foye WO, et al. Synthesis and evaluation of N-alkanoyl-S-benzyl-L-cysteinylglutamic acid esters as glyoxalase I inhibitors and anticancer agents. J Pharm Sci. 1984 Apr;73(4):559-61. [2]. Milos I. Djuran,et al. Reactivity of chloro- and aqua(diethylenetriamine)platinum(II) ions with glutathione, S-methylglutathione, and guanosine 5'-monophosphate in relation to the antitumor activity and toxicity of platinum complexes. Inorg. Chem. 1991, 30, 12, 2648-2652