[Studies of histone-nonhistone complex].

A chromatin protein complex was isolated from the calf thymus using hydroxyapatite without denaturants. Polyacrylamide gel electrophoresis showed that this complex consisted of five histones and nonhistone proteins. The complex is stable in 2 M sodium chloride. As the evidence of its stability the results are presented or rechromatography on hydroxyapatite, of gel-filtration on Sephadex G-150 and of polyacrylamide gel electrophoresis after crosslinking proteins by formaldehyde under mild conditions. It is suggested, that hydrophobic interactions which take place under high ionic strength due to the counteraction of protein charged groups, are among the possible mechanisms. This is supported by partial dissociation of the complex with a decrease in the sodium chloride concentrations in the solution.