Abstract
A 2:2 complex of proflavine and deoxycytidylyl-3′,5′-guanosine has been crystallized and its structure determined by x-ray crystallography. The two dinucleoside phosphate strands form self complementary duplexes with Watson Crick hydrogen bonds. One proflavin is asymmetrically intercalated between the base pairs and the other is stacked above them. The conformations of the nucleotides are unusual in that one strand has C3′,C2′ endo mixed sugar puckering and the other has C3′,C3′ endo deoxyribose sugars. These results show that the conformation of the 3′ sugar is of secondary importance to the intercalated geometry.