METHYLMERCURY(II) SULFHYDRYL INTERACTIONS - POTENTIOMETRIC DETERMINATION OF THE FORMATION-CONSTANTS FOR COMPLEXATION OF METHYLMERCURY(II) BY SULFHYDRYL CONTAINING AMINO-ACIDS AND RELATED MOLECULES, INCLUDING GLUTATHIONE

Formation constants for the interaction of methylmercury(II) with 2-mercaptoethanol, mercaptoacetic acid, O-methyl-mercaptoacetate, 2-mercaptosuccinic acid, L-cysteine, D,L-penicillamine, N-acetyl-D,L-penicillamine, glutathione, thiocholine, and 4-mercapto-N-methylpiperidine have been determined by potentiometric titration. For the equilibrium [Formula: see text], log β occurs in the range 14.60(1)–17.14(1), with the lowest value obtained for the cationic complex of thiocholine, [Formula: see text]. Acid dissociation constants for the ligands are reported. Formation constants for the addition of both one and two equivalents of MeHg(II) to L-cysteine have been determined, giving log K ca. 4.1 for the reaction[Formula: see text]occurring at low pH, and log K 8.8 for the reaction[Formula: see text]occurring at higher pH.