Mutual arrangement of histone H1 molecules in extended chromatin: Chymotryptic digestion of cross-linked H1 histone dimers

Mutual arrangement of histone H1 molecules in chromatin extended in low salt—EDTA buffer and additionally in the presence of urea was studied by means of reversible cross-linking combined with chymotryptic digestion. In the chromatins tested, the chymotryptic halves of H1 were cross-linked in all possible combinations; i.e., C—C, C—N and N—N. The results imply that the mutual arrangement of H1 histones is determined by the structure of extended nucleosomal chain, rather than chromatin superstructure.