Detection of a glutathionyl-carbonylated group (GS-CO-) on D-dopachrome tautomerase with preferential binding of GS-CO- to MIF proteins in rat livers damaged by carbon tetrachloride

Liver damage has been induced in animal experiments using carbon tetrachloride (CCl4), a potent hepatotoxin. CCl4 is activated by cytochrome P450 2E1, which results in the formation of various metabolites including phosgene. Although D-dopachrome tautomerase (DDT) is abundant in the liver, its role currently remains un-clear. The biological activity of DDT, for which the N-terminal proline is a key site, has been detected in various tissues. We herein incidentally detected a 333 Da modification to the N-terminal proline of DDT in rat livers damaged by CCl4. We identified that this modification as glutathionyl carbonylated group, which was formed by condensation of phosgene and reduced glutathione (GSH). We examined other glutathionyl-carbonylated pro-teins using two dimensional-polyacrylamide gel electrophoresis, mass spectrometry, and Western blotting for GSH, and detected only one glutathionyl-carbonylated protein, macrophage migration inhibitory factor (MIF). DDT belongs to the MIF family of proteins, and amino acid sequence identity between DDT and MIF is 33%. We concluded that MIF family proteins are major targets for glutathionyl carbonylation.

Automated summary

Liver damage was induced in animal experiments using carbon tetrachloride (CCl4). CCl4 is activated by cytochrome P450 2E1, resulting in the formation of various metabolites including phosgene. D-dopachrome tautomerase (DDT) was found to have a glutathionyl carbonylated group at its N-terminal proline in rat livers damaged by CCl4. Major targets for glutathionyl carbonylation were identified as macrophage migration inhibitory factor (MIF) and other MIF family proteins.