Histone III

Eighteen tryptic peptides, varying from 2 to 33 residues, plus free arginine and alanine were isolated from N-maleylated calf thymus histone III. The amino acid sequences of 17 of the peptides were established completely, but the sequence of a 33-residue peptide was only partially determined. Together, these peptides account for 135 residues, including the 2 cysteinyl residues which are present in histone III but not in other histones of calf thymus. Two lysyl residues are partially e-N-acetylated. In this study 1 lysyl residue was found to be e-N-methylated. In a more comprehensive investigation (DeLange, R. J., Hooper, J. A. and Smith, E. L. (1973) J. Biol. Chem. 248, 3261) 2 lysyl residues were modified at the e-amino group as the mono-, di-, and trimethyl derivatives.