The primary goal has been the elucidation of the structures of reactive metabolites responsible for the carcinogenic, cytotoxic and mutagenic activity of drugs, polycyclic aromatic hydrocarbons and other environmental chemicals. The approach taken consists of: i) study of the metabolism of the chemicals with liver microsomes and with purified cytochromes P450 and epoxide hydrolase, ii) synthesis of oxidative metabolites, iii) evaluation of the mutagenicity and tumorigenicity of the synthetic metabolites, iv) elucidation of the roles of the cytochrome P450 system and epoxide hydrolase in modulating the mutagenicity of these metabolites, v) determination of the rates and products of reactions of arene oxides and diol epoxides with biopolymers and model compounds, and vi) search for agents capable of preventing the tumorigenicity of reactive metabolites. Work during the past year has focused in two areas. i) Studies of the reaction mechanisms of K-region arene oxides have elucidated the role of the intrinsic chemical reactivity at each epoxide carbon. Conformational factors play a key role in the determination of rates and products of solvolytic cleavage and epoxide hydrolase-catalyzed hydrolysis. Our results also suggest that the transition state for nucleophilic attack of methoxide ion on the K-region arene oxides (a model for attack of water catalyzed by epoxide hydrolase) involves a partial positive charge on the carbon that undergoes nucleophilic substitution. ii) Synthetic studies have produced biologically significant oligonucleotides containing specific diol epoxide adducts. An adduct corresponding to trans opening of the (1R,2S)-diol (3S,4R)-epoxide of phenanthrene by the exocyclic amino group of deoxyadenosine (dA) was incorporated into a nonanucleotide comprising codons 60-62 of the human K-ras b oncogene. In duplexes formed by this adducted oligonucleotide, substitution of deoxyguanosine for thymidine in the complementary strand opposite the modified dA had almost no effect on the melting temperature. This result suggests a possible role for such base-pair """"""""mismatches"""""""" in mutations caused by diol epoxide adduct formation.

Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
United States
Zip Code
Yagi, Haruhiko; Frank, Heinrich; Seidel, Albrecht et al. (2007) Synthesis and absolute configuration of cis- and trans-opened cyclopenta[cd]pyrene 3,4-oxide N2-deoxyguanosine adducts: conversion to phosphoramidites for oligonucleotide synthesis. Chem Res Toxicol 20:650-61
Iyer, Prema C; Yagi, Haruhiko; Sayer, Jane M et al. (2007) 3'-H-phosphonate synthesis of chiral benzo[a]pyrene diol epoxide adducts at N(2) of deoxyguanosine in oligonucleotides. Chem Res Toxicol 20:311-5
Yagi, Haruhiko; Jerina, Donald M (2007) Fluorinated alcohol mediated control over cis vs trans opening of benzo[a]pyrene-7,8-diol 9,10-epoxides at C-10 by the exocyclic amino groups of O6-allyl protected deoxyguanosine and of deoxyadenosine. J Org Chem 72:6037-45
Bauer, Jacob; Xing, Guangxin; Yagi, Haruhiko et al. (2007) A structural gap in Dpo4 supports mutagenic bypass of a major benzo[a]pyrene dG adduct in DNA through template misalignment. Proc Natl Acad Sci U S A 104:14905-10
Wang, Ben; Sayer, Jane M; Yagi, Haruhiko et al. (2006) Facile interstrand migration of the hydrocarbon moiety of a dibenzo[a,l]pyrene 11,12-diol 13,14-epoxide adduct at N2 of deoxyguanosine in a duplex oligonucleotide. J Am Chem Soc 128:10079-84
Johnson, Allison A; Sayer, Jane M; Yagi, Haruhiko et al. (2006) Effect of DNA modifications on DNA processing by HIV-1 integrase and inhibitor binding: role of DNA backbone flexibility and an open catalytic site. J Biol Chem 281:32428-38
Yakovleva, Lyudmila; Handy, Christopher J; Yagi, Haruhiko et al. (2006) Intercalating polycyclic aromatic hydrocarbon-DNA adducts poison DNA religation by Vaccinia topoisomerase and act as roadblocks to digestion by exonuclease III. Biochemistry 45:7644-53
Batra, Vinod K; Shock, David D; Prasad, Rajendra et al. (2006) Structure of DNA polymerase beta with a benzo[c]phenanthrene diol epoxide-adducted template exhibits mutagenic features. Proc Natl Acad Sci U S A 103:17231-6
Choudhary, Saba; Doherty, Kevin M; Handy, Christopher J et al. (2006) Inhibition of Werner syndrome helicase activity by benzo[a]pyrene diol epoxide adducts can be overcome by replication protein A. J Biol Chem 281:6000-9
Chiapperino, Dominic; Cai, Mangmang; Sayer, Jane M et al. (2005) Error-prone translesion synthesis by human DNA polymerase eta on DNA-containing deoxyadenosine adducts of 7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene. J Biol Chem 280:39684-92

Showing the most recent 10 out of 64 publications