New insights into the metabolism of organomercury compounds: Mercury-containing cysteine S-conjugates are substrates of human glutamine transaminase K and potent inactivators of cystathionine γ-lyase

► In biological systems, Hg may exist as cysteine conjugates of CH3Hg and Hg2+. ► These conjugates [CH3Hg-S-Cys and Cys-S-Hg-S-Cys] resemble methionine and cystine. ► They are substrates for amino acid transporters and glutamine transaminase K. ► They are also potent inhibitors of cystathionine γ-lyase. ► Interaction of S-conjugates with transporters/enzymes may contribute to Hg toxicity.