Isolation Of Acidic Protein Research Articles

Preparation and some properties of strongly acidic proteins from calf-thymus nucleohistone.

The isolation of acidic proteins from calf-thymus nucleohistone (starting from purified nuclei) is reported. The method involved dissociation in 1 M KCl solution. Denaturating agents were not used at all. After electrophoresis on polyacrylamide gel, fractions containing a small number of components were obtained. The fractions display high ratios of acidic to basic amino acids, the ratios ranging from 4.0 to 1.5. In all fractions, the major components were of molecular weights in the ranges 12000-15000 and 24000-28000 as determined by gel-disc electrophoresis in dodecylsulphate and by equilibrium ultracentrifugation. Minor components of high molecular weights were also present. Amino-acid analyses are also reported. The tryptophan content was determined by a fluorometric method. Circular dichroism spectra depict a very low content of alpha-helicity that did not increase at higher ionic strength. A marked RNA-polymerase activity was found in one fraction.

Chromatin acidic proteins with high affinity for nucleohistone and DNA

Isolation of acidic proteins with high affinity for DNA and/or nucleohistone, from rat liver chromatin, is described. It is rapid and avoids the use of harsh extraction conditions. The isolated proteins comprise less than 4% of the total nuclear proteins, and are distinct from the other major groups of nuclear proteins in their solubility properties and SDS-acrylamide gel electrophoresis patterns. They bind to DNA 5 to 7 times more effectively than other nuclear acidic proteins.