Abstract: The interaction of antitumor activity complex, cis-[Pt (NH₃)₂, (4-methylpyridine )Cl]No₃ with S-methylglutathione (GS-Me) was determined using the method of proton NMR. The proton resonances of Pt complex and GS-Me were used as an indication of whether the reaction was completed or not. The results indicate that a Pt- to GS-Me ratio of 1:1 is required to bind all available GS-Me- The complex of Pt with GS-Me were titrated over pHrange 1-12. The pHdependence of chemical shifts of g₁, g₃, g₄ and g₅ is depicted.It is concluded that GS-Me bind to Pt via Satom and no amino and carboxyl groups coordi-nate to Pt. The reaction mechanism was discussed and the time course of reaction was recorded. The reaction of Pt with GS-Me suggests a process in two steps: the first step in-volves the formation of Pt-GS-Me adduct via Satom, then ammonia coordinated trans to Swill be lbaialized due to the high trans effect of S. The rate constant of reaction between Pt complex and GS-Me was determined by proton NMR, k=0.017 L. mol^-1. s^-1 (pH3.1)and 0.013 L. mol^-1. s^-1(pH 7.2).

Key words: Platinum complex, S-methylglutathione, ¹H NMR