Metabolic and Chemical Properties of Basic Proteins Isolated From Nuclei of Rat Liver and Thymus Gland

Abstract

1. The effects of alkylating agents and disulphides on the thiol-containing proteins of nuclei from rat thymus and liver were studied. Three protein fractions were examined: histones extracted with 50mm- and 250mm-hydrochloric acid and the residual protein. None of the reagents selectively reacted with any one of the protein fractions. 2. Amino acid uptake in vitro into the histones of nuclei from rat thymus was analysed by preparative electrophoresis of the proteins extracted with 50mm- and 250mm-hydrochloric acid. After 1hr. at 37 degrees the greater incorporation was into the proteins extracted with 50mm-hydrochloric acid. 3. Preparative electrophoresis was used to study the relative thiol contents of the proteins of the 50mm-hydrochloric acid extract from thymus nuclei by labelling the histones in vitro with (14)C-labelled N-ethylmaleimide. 4. The capacity of the proteins extracted from rat thymus with 50mm- and 250mm-hydrochloric acid, and of the components from these extracts separated by preparative electrophoresis, to combine with DNA and to depress DNA-dependent RNA synthesis was studied. The histones extracted with 50mm-hydrochloric acid were more lysine-rich than those extracted with 250mm-hydrochloric acid. Wide variations were found in the abilities of the separated components to depress RNA synthesis.

Metabolic properties of histones from rat liver and thymus gland

“…Examination of the histones that could be separated by preparative electrophoresis on polyacrylamide gel showed that when rat-thymus nuclei were incubated with 14C-labelled amino acids there was a marked difference in rate of uptake of the amino acids into the different proteins, one component (6) having an especially high uptake (Ord, Raaf, Smit & Stocken, 1965). In the electrophoretic procedure used, 2-3 days were required for the separation of the different components, so that proteolysis could have occurred, and only 5mg.…”

Die Haftung von Homotransplantaten unter Behandlung mit Histon

“…Werden gereinigte IIistone einem Kulturmedium von Zellen zugesetzt, dann dringen sie in die Zellen ein (Fischer u. Brandis, 1954) und hemmen deren RNA-und DNA-Synthese (Allfrey et al, 1963 ;Fischer u. Wagner, 1954;Moskowitz et al, 1969;Ord et al, 1964;Pohjanpelto, 1967 ;Ryser and Hancock, 1965 ;Vorobyev, 1969). Danach war zu erwarten, dab kfinstlich zugeffihrte IIistone die Proteinsynthese und somit auch die Bildung von AntikSrpern hemmen, dab Itistone sich also/~hn]ich wie Immunosuppressiva verhalten.…”

Histone F1 from rat thymus. Subfractionation and incorporation of [32P]phosphate in vitro

“…Nuclei were isolated from thymus glands of rats (120g body wt.) in 0.25M-sucrose-5mM-MgCl2-5mM-tris-HCl buffer, pH7.2, as described by Ord, Raaf, Smit & Stocken (1965).…”