ON THE TERTIARY STRUCTURE OF SATELLITE DNA

The primary structure of the Citrus ichangensis satellite DNA repeatin g unit has been estimated. The repeat is 181 bp long and contains four pentanucleotides of adenine residues. Oligomer forms of the stDNA rep eating unit were detected by a partial hydrolysis of the C ichangensis stDNA by BspI restriction endonuclease. Experiments on comparative mo bility of oligomers in agarose and polyacrylamide gels evidenced a cer tain retardation of those in polyacrylamide gel indicating to a slight bend in the repeating unit. The BEN computer program [9] was employed to calculate the spatial positions of monomer and oligomer axes of th e satellite DNA repeating unit of Citrus ichangensis, mouse and Africa n green monkey, and to plot their two-dimensional projections. The ben ds in the monomer for higher oligomer form proved to result in a hypot hetical solenoid-like structure, termed coiled double helix (CDH).