Main binding sites of the carcinogen, 4-nitroquinoline 1-oxide in nucleic acids

4-Hydroxyaminoquinoline 1-oxide, the reduced metabolite of 4-nitroquinoline 1-oxide, was reacted with homopolyribonucleotides through the catalysis of an activating enzyme. It bound specifically to poly(G), poly(A) and poly(X) but negligibly to poly(C), poly (U) and poly(I). Chromatographic analysis of the acid hydrolysates of carcinogen-bound polynucleotides revealed that the reaction of the carcinogen with polynucleotides yielded two guanine, one adenine and two xanthine adducts. The same kinds of guanine and adenine adducts were found in DNA or RNA isolated from Escherichia coli and mammalian cells that had been exposed to the carcinogen. Analysis of nucleic acids isolated from 4-hydroxyaminoquinoline 1-oxide-treated cells revealed that 4-hydroxy-aminoquinoline reacts in vivo preferentially with guanines, to a less, but significant, extent with adenines and not significantly with pyrimidines.