Principles of covalent binding of reactive metabolites and examples of activation of bis-electrophiles by conjugation.

Guengerich FP
Arch Biochem Biophys. 2005 433 (2): 369-78

PMID: 15581593 · DOI:10.1016/j.abb.2004.07.035

Mechanisms of toxicity continue to be important in developing rational strategies to deal with chemicals present in the environment. Understanding and predicting toxicity have also become a critical step in the process of drug development. Covalent binding of chemicals to macromolecules is one aspect of toxicity, and the principles and outcomes of the process are considered. Two examples of chemicals for which several aspects of metabolism and reactions are understood are aflatoxin B(1) and polyhalogenated olefins. Ethylene dibromide is a compound that is activated to genotoxic half-mustards by conjugation with glutathione or the DNA repair protein O(6)-alkylguanine DNA alkyltransferase (AGT). The AGT reaction is unusual, in that crosslinking of the protein to DNA increases mutagenicity. One of the involved mechanisms is formation of N(7)-guanyl crosslinks and depurination to produce G-->T transversions; other reactions appear to yield the additional mutagenic events. The phenomenon of thiol conjugation to increase mutagenicity is widespread among bis-electrophiles.

MeSH Terms (32)

Aflatoxin B1 Animals Biotransformation Butadienes Cross-Linking Reagents DNA DNA Adducts DNA Damage DNA Repair Dose-Response Relationship, Drug Enzyme Activation Escherichia coli Ethylene Dibromide Forecasting Genes, Bacterial Glutathione Half-Life Humans Hydrolysis Kinetics Lysine Models, Chemical Molecular Structure Mutagenicity Tests Mutagens Mutation O(6)-Methylguanine-DNA Methyltransferase Oxidation-Reduction Salmonella typhimurium Signal Transduction Tetrachloroethylene Trichloroethylene

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