Nucleotide-selective cleavage of duplex DNA by nitric oxide.

In the presence of sodium nitrite and sodium hydrosulfite, the produced NO has been confirmed by the detection of bleomycin-Fe(II)-NO adduct complex. Nitric oxide clearly induces DNA form change of form I-->forms II & III. Of special interest is the fact that (1) NO attacks guanine bases as the most preferential cleaving sites and (2) the frequency of the NO-induced cutting decreases in the order G > C > A > T. The preferred cleavage at GC sequences by NO may correlate to predominant mutagenicity at GC sites by nitric oxide.