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 , log β occurs in the range 14.60(1)–17.14(1), with the lowest value obtained for the cationic complex of thiocholine, . 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 reactionoccurring at low pH, and log K 8.8 for the reactionoccurring at higher pH.