title: A novel post-ligation thioesterification device enables peptide ligation in the N to C direction: synthetic study of human glycodelin.
abstract: Human glycodelin consists of 162 amino acid residues and two N-linked glycans at Asn(28) and Asn(63) . In this study, we synthesized it by a fully convergent strategy using native chemical ligation (NCL) in N to C direction. The four peptide segments corresponding to 1-31, 32-65, 66-105 and 106-162 sequences were synthesized by 9-fluorenylmethoxycarbonyl based solid-phase peptide synthesis. At the C-terminus of the second segment, N-ethyl-S-acetamidomethyl-cysteine was attached as a post-ligation thioesterification device. The N-terminal two segments were condensed by the homocysteine-mediated NCL at Leu-Met site, and the product was methylated to convert homocysteine to methionine. After deprotection of acetamidomethyl group on the N-ethylcysteine residue, the peptide was thioesterified by N-alkylcysteine-assisted method. The product was then ligated with the C-terminal half, which was obtained by the NCL of third and fourth segments, to give the full-length glycodelin.
authors.affiliation: Department of Applied Biochemistry, Faculty of Engineering, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa, 259-1292, Japan.
authors.forename: Takaomi
authors.initials: T
authors.lastname: Takenouchi
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Katayama
authors.forename: Yuko
authors.initials: Y
authors.lastname: Nakahara
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Nakahara
authors.forename: Hironobu
authors.initials: H
authors.lastname: Hojo
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids; D002851:Chromatography, High Pressure Liquid; D056148:Chromatography, Reverse-Phase; D003545:Cysteine / Q000737:chemistry; D004951:Esterification; D005449:Fluorenes; D000071816:Glycodelin; D006023:Glycoproteins / Q000138:chemical synthesis* / Q000302:isolation & purification; D006801:Humans; D060327:Solid-Phase Synthesis Techniques
chemical_list: D000596:Amino Acids; D005449:Fluorenes; D000071816:Glycodelin; D006023:Glycoproteins; C016456:N(alpha)-fluorenylmethyloxycarbonylamino acids; C045246:PAEP protein, human; D003545:Cysteine
keywords: N-alkylcysteine; glycodelin; native chemical ligation; peptide thioester; thioesterification