Selective isopeptide bond formation: coupling ubiquitin67–76 with histone 2A114–128 by use of the transfer active ester condensation technique

A peptide, ubiquitin67–76‐histone 2A114–128 fragment (UBH2AF), was synthesized by selective formation of an isopeptide bond between the C‐terminus of ubiquitin67–76 and the ε‐amino group of lysine‐119 in histone 2A114–128 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. Leu67‐His‐Leu‐Val‐Leu‐Arg‐Leu‐Arg‐Gly‐Gly76 | Val114‐Leu‐Leu‐Pro‐Lys(NH2)‐Lys119‐Thr‐Glu‐Ser‐His‐His‐Lys(NH2)‐Ala‐Lys(NH2)‐Gly128 UBH2AF