STRUCTURE OF THE A-DNA OCTAMER D(GGCATGCC)

The crystal structure of the self-complementary DNA octamer d(GGCATGCC ) has been determined to a resolution of 2.38 Angstrom and R factor of 17.1%. The structure is an A-DNA octamer duplex with Watson-Crick bas e pairing along its length. This sequence extends the investigation of octamer duplexes of the type d(GGX(4)CC) which assume P6(1) packing w ithin the crystallographic unit cell. The A-DNA duplex is non-linear w ith a helix axis curvature of 7 degrees and bending towards the DNA mi nor groove. In view of the biological importance of protein recognitio n of some A-DNA sequences the minor-groove geometry and helix-axis cur vature for this structure is compared with all others of the type d(GG XATXCC).