title: Semisynthesis of biologically active glycoforms of the human cytokine interleukin 6.
abstract: Human interleukin 6 (IL-6) is a potent cytokine with immunomodulatory properties. As the influence of N-glycosylation on the in vivo activities of IL-6 could not be elucidated so far, a semisynthesis of homogeneous glycoforms of IL-6 was established by sequential native chemical ligation. The four cysteines of IL-6 are convenient for ligations and require only the short synthetic glycopeptide 43-48. The Cys-peptide 49-183 could be obtained recombinantly by cleavage of a SUMO tag. The fragment 1-42 was accessible by the simultaneous cleavage of two inteins, leading to the 1-42 thioester with the native N-terminus. Ligation and refolding studies showed that the inherently labile Asp-Pro bond 139-140 was detrimental for the sequential C- to N-terminal ligation. A reversed ligation sequence using glycopeptide hydrazides gave full-length IL-6 glycoproteins, which showed full bioactivity after efficient refolding and purification.
authors.affiliation: Bioorganic Chemistry, Gebaeude NWI, University of Bayreuth, 95440 Bayreuth (Germany).
authors.forename: Andreas
authors.initials: A
authors.lastname: Reif
authors.forename: Sebastian
authors.initials: S
authors.lastname: Siebenhaar
authors.forename: Andrea
authors.initials: A
authors.lastname: Tröster
authors.forename: Marina
authors.initials: M
authors.lastname: Schmälzlein
authors.forename: Carolin
authors.initials: C
authors.lastname: Lechner
authors.forename: Phanindra
authors.initials: P
authors.lastname: Velisetty
authors.forename: Karen
authors.initials: K
authors.lastname: Gottwald
authors.forename: Claudia
authors.initials: C
authors.lastname: Pöhner
authors.forename: Irene
authors.initials: I
authors.lastname: Boos
authors.forename: Volker
authors.initials: V
authors.lastname: Schubert
authors.forename: Stefan
authors.initials: S
authors.lastname: Rose-John
authors.forename: Carlo
authors.initials: C
authors.lastname: Unverzagt
mesh_terms: D002851:Chromatography, High Pressure Liquid; D006801:Humans; D015850:Interleukin-6 / Q000138:chemical synthesis* / Q000737:chemistry; D013058:Mass Spectrometry; D020033:Protein Isoforms / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D015850:Interleukin-6; D020033:Protein Isoforms
keywords: cytokines; glycopeptides; glycoproteins; native chemical ligation; solid-phase synthesis