Proteolytic digestion studies of chromatin core-histone structure. Identification of the limit peptides of histones H3 and H4.

Trypsin digestion of chromatin results in a well-defined set of limit peptides (P1--P5) derived from the four core histones. Those from histones H3 and H4 have been identified. P1 is H3 residues 27--129; P4 is H4 residues 18--102 and P5 is H4 residues 20--102. The N-terminal sequences removed correlate well with the regions that undergo post-synthetic acetylation and which show the greatest degree of sequence conservation. Autolytic digestion of chromatin releases a peptide (P1') from H3 representing residues 21--135. The implications of protease digestion for the higher order structure of chromatin are discussed.