Mapping of the highest occupied molecular orbital of a DNA–RNA hybrid by cobalt–benzoyl peroxide oxidation

Ab initio calculations of the highest occupied molecular orbital (HOMO) of the guanine (G)-containing sequences with DNA–RNA hybrid geometry were performed at the HF 6-31G* level. Sequence dependent guanine oxidation with Co(II) and benzoyl peroxide (BPO) has been observed for a DNA–RNA hybrid as revealed by PAGE analysis of the reaction mixture after hot piperidine treatment. The DNA cleavage of 5′-GGG-3′ sequence was consistent with the selectivity predicted from calculated HOMOs of 5′-GGG-3′ sequence.