Distribution of histones in alkali-denatured chromatin studied by isopycnic centrifugation in alkaline metrizamide density gradients.
Three types of density gradients - neutral metrizamide, alkaline NaOH-metrizamide and alkaline triethanolamine-metrizamide - were used for studying the distribution of histones between the two DNA strands in alkali-denatured chromatin. It was found possible to avoid both protein redistribution and dissociation by using triethanolamine-metrizamide density gradients at pH 10.5. Under these conditions an alkali-denatured mixture of DNA and chromatin was well separated into the original DNA and DNP. When native or sonicated chromatin was denatured at pH 12.2 and centrifuged in a triethanolamine-metrizamide density gradient at pH 10.5 no peak of free DNA appeared. These results show that both DNA strands remain associated with histone molecules upon alkaline denaturation of chromatin.
D000818:Animals; D002499:Centrifugation, Density Gradient; D002843:Chromatin / Q000032:analysis*; D006657:Histones / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D008099:Liver / Q000032:analysis; D008970:Molecular Weight; D051381:Rats; D013010:Sonication
D002843:Chromatin; D006657:Histones