Sieving study of chromatin and histone-DNA complex by porous hollow fiber membranes

Permeation of chromatin isolated from human HeLa S3 cells and histone-DNA complex through regenerated cellulose hollow fibers was investigated as a model study of DNA removal for drug manufacturing using membrane technology. It was found that the permeation of histone-DNA and chromatin through the membranes having a mean pore diameter of 15 nm was substantially lower than the permeation of free DNA which did not complex with proteins based on the concentration determination of the feed and permeate solutions using UV spectroscopy. Direct observation to determine the existence of chromatin and histone-DNA complex in the permeate solution was also performed using atomic force microscopic imaging. No chromatin and chromatin-like structures were found in the examination of 10 areas of 1.0 x 1.0 mu m on the mica which had been adsorbed from the solution permeated through the membranes. Thus, the membranes having a mean pore diameter of 15 nm most likely reject the chromatin and histone-DNA complex that are observed to have an apparent width of 25-30 nm based on atomic force microscopic imaging.