Crystal Structure of a Carcinogen:Nucleoside Adduct¹

The product of reaction between the carcinogen, 7-bromomethyl-12-methylbenz[a]anthracene, and 2′-deoxyadenosine, i.e., N⁶-(12-methylbenz[a]anthracenyl-7-methyl)deoxyadenosine, has been prepared and characterized, and its structure has been determined by X-ray crystallographic techniques. The major structural features are: (a) the adenine and polycyclic aromatic hydrocarbon residues lie nearly perpendicular to one another; (b) the conformation about the glycosidic bond is syn, rather than anti, and an internal hydrogen bond between the deoxyribose 5′-hydroxyl group and N(3) of the adenine residue is present; and (c) the more planar anthracene portion of the hydrocarbon is stacked between adenine residues of other molecules throughout the crystal.