title: Non-enzymatic and microsome-dependent binding of poly-cyclic hydrocarbons to DNA and polynucleotides.
abstract: The binding of tritium-labeled 7,12-dimethylbenz[a]anthracene (DMBA), benzo[a]pyrene (BP) and 3-methylcholanthrene (MCA) to DNA or polynucleotides in vitro was re-examined both in the presence and in the absence of rat liver or human placental microsomes. A high level of non-enzymatic binding was evident when thymus DNA was used as acceptor. This non-enzymatic binding made it difficult to determine the effect of microsomes, except in the case of BP when induced rat microsomes were used. Better results were obtained using polynucleotides: a definite microsome-dependent binding occurred between all the polynucleotides and all the hydrocarbons tested. No clear evidence of binding catalysed by microsomes from human placenta was found except in polynucleotide-BP interactions: further studies are required to completely evaluate the ability of such nucleic acid-microsomal system for testing in vitro possible oncogenic substances in animals and humans.
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene / Q000378:metabolism*; D000818:Animals; D001551:Benz(a)Anthracenes / Q000378:metabolism*; D001580:Benzopyrenes / Q000378:metabolism*; D001665:Binding Sites; D004247:DNA / Q000378:metabolism*; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008748:Methylcholanthrene / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism*; D008862:Microsomes, Liver / Q000378:metabolism*; D010920:Placenta / Q000166:cytology / Q000378:metabolism; D011061:Poly A / Q000378:metabolism; D011068:Poly G / Q000378:metabolism; D011072:Poly U / Q000378:metabolism; D011119:Polynucleotides / Q000378:metabolism*; D011247:Pregnancy; D051381:Rats; D011955:Receptors, Drug
chemical_list: D001551:Benz(a)Anthracenes; D001580:Benzopyrenes; D011119:Polynucleotides; D011955:Receptors, Drug; D011061:Poly A; D011068:Poly G; D011072:Poly U; D008748:Methylcholanthrene; D015127:9,10-Dimethyl-1,2-benzanthracene; D004247:DNA