Structure of a stacked anthraquinone-DNA complex.

The crystal structure of the telomeric sequence d(UBrAGG) interacting with an anthraquinone derivative has been solved by MAD. In all previously studied complexes of intercalating drugs, the drug is usually sandwiched between two DNA base pairs. Instead, the present structure looks like a crystal of stacked anthraquinone molecules in which isolated base pairs are intercalated.

Variable role of ions in two drug intercalation complexes of DNA.

The crystal structures of the hexamer duplex d(CGTACG)(2) complexed with the intercalating anthraquinone derivative 1,5-bis[3-(diethylamino)propionamido]anthracene-9,10-dione and the acridine derivative 9-acridinyl tetralysine have been solved at 2.0- and 1.4-A resolution, respectively.

DNA variability in five crystal structures of d(CGCAATTGCG).

The deoxyoligonucleotide d(CGCAATTGCG) has previously been crystallized in four different space groups. The crystals diffract to moderate resolution (2.3-2.

A thymine tetrad in d(TGGGGT) quadruplexes stabilized with Tl+/Na+ ions.

We report two new structures of the quadruplex d(TGGGGT)4 obtained by single crystal X-ray diffraction. In one of them a thymine tetrad is found. Thus the yeast telomere sequences d(TG1-3) might be able to form continuous quadruplex structures, involving both guanine and thymine tetrads.