title: Glutamate dehydrogenase covalently binds to a reactive metabolite of acetaminophen.
abstract: The mechanism of the hepatotoxicity of the analgesic acetaminophen is believed to be mediated by covalent binding to protein; however, critical targets which effect the toxicity are unknown. It has been shown that mitochondrial respiration in vivo is inhibited in mice as early as 1 h following a hepatotoxic dose of acetaminophen, and it is postulated that covalent binding to critical mitochondrial proteins may be important. A time course of mitochondrial proteins stained with anti-acetaminophen in an immunoblot detected two major adducts of 50 and 67 kDa as early as 30 min after a hepatotoxic dose of acetaminophen in mice. To further understand the role of covalent binding to mitochondrial proteins and acetaminophen hepatotoxicity, we have purified and identified a 50 kDa mitochondrial protein which becomes covalently bound to a reactive metabolite of acetaminophen. An N-terminal sequence of the 50 kDa adduct was 100% homologous with the deduced amino acid sequence of glutamate dehydrogenase. In addition, the purified protein was immunochemically reactive with rat liver anti-glutamate dehydrogenase. Enzyme activity of glutamate dehydrogenase was significantly decreased in mice 1 h following hepatotoxic treatment with acetaminophen. These data suggest that acetaminophen hepatotoxicity may in part be mediated by covalent binding to glutamate dehydrogenase.
authors.affiliation: Division of Toxicology, University of Arkansas for Medical Sciences, Little Rock 72205-7199, USA.
authors.forename: N C
authors.initials: NC
authors.lastname: Halmes
authors.forename: J A
authors.initials: JA
authors.lastname: Hinson
authors.forename: B M
authors.initials: BM
authors.lastname: Martin
authors.forename: N R
authors.initials: NR
authors.lastname: Pumford
mesh_terms: D000082:Acetaminophen / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D018736:DNA Adducts / Q000494:pharmacology*; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000378:metabolism*; D005969:Glutamate Dehydrogenase / Q000378:metabolism*; D006657:Histones / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008930:Mitochondria, Liver / Q000201:enzymology; D008969:Molecular Sequence Data; D009532:Nickel / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D010710:Phosphates / Q000494:pharmacology; D011485:Protein Binding
chemical_list: D018736:DNA Adducts; D006657:Histones; D010710:Phosphates; D000082:Acetaminophen; D009532:Nickel; D005969:Glutamate Dehydrogenase; D003849:Deoxyguanosine