Abstract: Objective To investigate the nucleosome positioning of DNA repeats sequence in vitro which can cause human genetic disease. Methods The recombinant plasmids containing (GAA) 42, (ATTCT)43, (GCCT)18 and 601 sequence were cloned.The histone and plasmids were used to assemble chromatin structure in vitro,and then analyzed by agarose gel electrophoresis after micrococcal nuclease digestion. Results The plasmid containing ATTCT repeats sequence was more easy to form nucleosome than containing GAA repeats sequence in vitro. Conclusion The recombinant plasmids’ ability to form chromatin structure were changed because of the insert of the different repeats sequence fragment.

Key words: DNA repeat sequence, Nucleosome positioning, Assembly chromatin in vitro, Micrococcal nuclease,, Chromatin structure