Chemical cross-linking of H1 histone to the nucleosomal histones.

When whole steer kidney nuclei were treated with dimethyl-3,3'-dithiobisproprionimidate, N,N'-bis(2-carboxyimidomethyl) tartaramide dimethyl ester, or 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide under approximately physiological ionic conditions, H1 histone was cross-linked to each of the four histones in the nucleosome core. The carbodiimide reagent, which introduces no atoms between the amino acid side chains being joined, seemed to give the same result as did the longer di-imidate cross-linking reagents. When conditions were optimized for the production of of H1-containing dimers, the total yield of H1-core histone heterodimers was nearly equal to the yield of H1 homodimers. Naturally occurring H1 dimers and cross-linked heterodimers of high mobility group proteins 14 and 17 with H1 and core histones were also observed.