SOLUBILIZATION AND PARTIAL FRACTIONATION OF SULPHUR-CONTAINING NUCLEAR PROTEINS OF HEPATOMA 223 ASCITES CELLS

Nuclei, free from cytoplasmic contamination, have been prepared from rat hepatoma 223 ascites cells disrupted by hypo-osmotic shock. Two extractions of these nuclei with 8m urea 0·05m sodium phosphate pH 7·6 removed 89% of the total nuclear thiol material and 70% of the protein. A further two extractions with 0·25m HCl removed a further 6% of the thiol material and 23% of the protein. No DNA was solubilized by these procedures. Fractionation of the urea soluble material on G-100 Sephadex, DEAE and CM-celluloses separated RNA from seven protein components, the amino-acid composition of which is reported. Further attempts at fractionation of an acidic, glycine-rich fraction on G-200 Sephadex, by gel electrophoresis and isoelectric focussing are also described. Separation of some of the thiol components of the urea insoluble, 0·25m HCl soluble nuclear proteins (histones) on microgranular CM-cellulose has been achieved. © 1969.