Selective isopeptide bond formation: coupling ubiquitin(67-76) with histone 2A(114-128) by use of the transfer active ester condensation technique.

A peptide, ubiquitin(67-76)-histone 2A(114-128) fragment (UBH2AF), was synthesized by selective formation of an isopeptide bond between the C-terminus of ubiquitin(67-76) and the epsilon-amino group of lysine-119 in histone 2A(114-128) which contained 4 lysine residues at positions 118, 119, 125 and 127, respectively. The transfer active ester condensation technique, together with the Tnm amine protecting group, were used successfully in the peptide segment coupling reaction. [structure: see text]