Metal-polynucleotide interactions. A comparison of carcinogenic and non-carcinogenic metals in vitro.

The effects of divalent cations on mixing curves of synthetic polyribonucleotides in solution are described. Manganese and cadmium chlorides at 10(-3) M induce changes suggestive of base mispairing. MnCl2 induces mispairing in complexes formed between both poly(I) and poly(C,U) and poly(I) and poly(C,A) while CdCl2 affects base pairing between poly(I) and poly(C,U) only. By contrast, the chlorides of magnesium and zinc show no mispairing effects with either polymer pair. Manganese and cadmium are both reported carcinogens in animals while magnesium and zinc are not. The possibility that direct metal-nucleic acid interaction may be involved in metal carcinogenesis is discussed.