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Chemical synthesis of a polypeptide backbone derived from the primary sequence of the cancer protein NY‐ESO ‐1 enabled by kinetically controlled ligation and pseudoprolines
Author(s) -
Harris Paul W. R.,
Brimble Margaret A.
Publication year - 2015
Publication title -
peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.22621
Subject(s) - native chemical ligation , chemistry , peptide , chemical ligation , cysteine , residue (chemistry) , solid phase synthesis , peptide synthesis , thioester , combinatorial chemistry , stereochemistry , biochemistry , enzyme
The cancer protein NY‐ESO‐1 has been shown to be one of the most promising vaccine candidates although little is known about its cellular function. Using a chemical protein strategy, the 180 amino acid polypeptide, tagged with an arginine solubilizing tail, was assembled in a convergent manner from four unprotected peptide α‐thioester peptide building blocks and one cysteinyl polypeptide, which were in turn prepared by Boc and Fmoc solid phase peptide synthesis (SPPS) respectively. To facilitate the assembly by ligation chemistries, non‐native cysteines were introduced as chemical handles into the polypeptide fragments; pseudoproline dipeptides and microwave assisted Fmoc SPPS were crucial techniques to prepare the challenging hydrophobic C‐terminal fragment. Three sequential kinetically controlled ligations, which exploited the reactivity between peptide arylthioesters and peptide alkylthioesters, were then used in order to assemble the more tractable N‐terminal region of NY‐ESO‐1. The ensuing 147 residue polypeptide thioester then underwent successful final native chemical ligation with the very hydrophobic C‐terminal polypeptide bearing an N‐terminal cysteine affording the 186 residue polypeptide as an advanced intermediate en route to the native NY‐ESO‐1 protein. © 2015 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 104: 116–127, 2015.