Separate deamination mechanisms for isomeric styrene oxide induced N-1-adenine adducts

[GRAPHICS] Styrene 7,8-oxide (SO) induced N-1-2'-deoxyadenosine 5'-phosphate (AMP) add ucts deaminate to corresponding inosine derivatives. For the beta-isomer of N-1-SO-AMP, the chiral a carbon was found to be involved in the hydrolytic deamination, suggesting formation of an oxazolinium ring as an intermediat e and that a water molecule attacks the benzylic carbon, The mechanism diff ers from the one suggested for the alpha-isomer of N-1-SO-AMP, for which de amination occurs by direct attack of water at the 6-position of purine ring .