Major grove (S)-alpha-(N(super 6)-adenyl)styrene oxide adducts in an oligodeoxynucleotide containing the human N-ras codon 61 sequence: conformations of the S(61,2) and S(61,3) sequence isomers from 1H NMR

High-resolution 1H NMR spectroscopy of the S(61,2) and S(61,3) adducts in an oligodeoxynucleotide possessing the human N-ras codon 61 indicates that the isomers are oriented in a direction opposite to that of the styrene ring in the major grove. The styrene ring is oriented in the 3'-direction in the S adducts. The S adducts exhibit a strong sequence effect. Two conformations of the S(61,2) adduct exist in equilibrium but the S(61,3) adduct has a single conformation.