Degradation of methyl mercury glutathione by the pancreatic enzymes in bile

Abstract

Methyl mercury glutathione (MMGSH), a major methyl mercury derivative excreted in the bile, was converted stepwise into methyl mercury cysteine (MMCys) by the enzymes in the bile as well as γ-glutamyl transpeptidase (γ-GTP, EC 2.3.2.2), contaminated with cysteinylglycine hydrolase (EC 3.4.3.5), purified from rat kidney. The responsible enzymes present in the bile seemed to be γGTP and cysteinylglycine hydrolase. The reaction products were determined by ion-exchange chromatographic analysis of methyl mercury. The stepwise conversion of MMGSH to methyl mercury cysteinylglycine (MMCysGly) and MMCys was demonstrated by thin-layer chromatographic and DEAE-Sephadex column chromatographic analyses. γ-GTP in the bile seemed to come from the pancreas, because increases or decreases of γ-GTP activity in the bile correlated well with α-amylase activity (EC 3.2.2.1), a representative pancreatic enzyme, after pancreozymin injection.