Selective Coupling at the α-Amino Group of Cysteine Using Transfer Active-ester-condensation Technology to Synthesize a Linear Octadecapeptide

The peptide segment Fmoc-Ubiquitin67–76-NHNH2 was converted to the active ester Fmoc-Ubiquitin67–76-OCt and reacted with an unprotected seven residue fragment (H-mNGF110–117-OH) from murine Nerve Growth Factor, which contains a Cys at the N-terminus and a free ε-amino group at Lys115, using transfer active-ester-condensation (TAEC) technology. The linear product H-Ubiquitin67–76-murine Nerve Growth Factor110–117-OH was formed exclusively through the native chemical ligation mechanism.