title: Fully Synthetic Granulocyte Colony-Stimulating Factor Enabled by Isonitrile-Mediated Coupling of Large, Side-Chain-Unprotected Peptides.
abstract: Human granulocyte colony-stimulating factor (G-CSF) is an endogenous glycoprotein involved in hematopoiesis. Natively glycosylated and nonglycosylated recombinant forms, lenograstim and filgrastim, respectively, are used clinically to manage neutropenia in patients undergoing chemotherapeutic treatment. Despite their comparable therapeutic potential, the purpose of O-linked glycosylation at Thr133 remains a subject of controversy. In light of this, we have developed a synthetic platform to prepare G-CSF aglycone with the goal of enabling access to native and designed glycoforms with site-selectivity and glycan homogeneity. To address the synthesis of a relatively large, aggregation-prone sequence, we advanced an isonitrile-mediated ligation method. The chemoselective activation and coupling of C-terminal peptidyl Gly thioacids with the N-terminus of an unprotected peptide provide ligated peptides directly in a manner complementary to that with conventional native chemical ligation-desulfurization strategies. Herein, we describe the details and application of this method as it enabled the convergent total synthesis of G-CSF aglycone.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Roberts
authors.forename: Eric V
authors.initials: EV
authors.lastname: Johnston
authors.forename: Jae-Hung
authors.initials: JH
authors.lastname: Shieh
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Sondey
authors.forename: Ronald C
authors.initials: RC
authors.lastname: Hendrickson
authors.forename: Malcolm A S
authors.initials: MA
authors.lastname: Moore
authors.affiliation: Department of Chemistry, Columbia University , New York, New York 10027, United States.
authors.forename: Samuel J
authors.initials: SJ
authors.lastname: Danishefsky
mesh_terms: D000595:Amino Acid Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D016179:Granulocyte Colony-Stimulating Factor / Q000737:chemistry*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*
chemical_list: D010455:Peptides; D016179:Granulocyte Colony-Stimulating Factor