Nucleosome mono-,di-, tri-, and tetramers from chicken embryo chromatin

The fractionation of gram quantities of nuclease digested chromatin from chicken embryos into nucleosome mono-, di-, tri-, and tetramers is described in detail. Each of these nucleosomal species contains a fraction soluble in 0.1 M KC1 that decreases with increasing repeat number. Less histone HI is associated with the nucleosome fractions soluble as compared to the respective fractions precipitated in 0.1 M KC1. Thermal denaturation pro-files of the four nucleosomal species are monophaslc. The same T of 78 C has been determined for the KCl-soluble nucleosomes and for the KCl-insoluble monomer. The T of the KCl-insoluble oligomers is 79-8 C. Multiphasic melting curves were recorded for nucleosomal material that was concentrated by lyophilisation or stored at k °C in 0.25 mM EDTA. Total nucleosome mono-, di-, tri-, and tetramers (consisting of both the fraction soluble and insoluble in 0.1 M KC1) have been analyzed concerning their se-dimentation, diffusion, partial specific volume, and molecular weight and compared with the ' sedimentation and molecular weight data of KCl-soluble nucleosome mono- and tetramers