Bioorganic Chemistry, Gebaeude NWI, University of Bayreuth, 95440 Bayreuth (Germany).
Angew Chem Int Ed Engl. 2014 Nov 3;53(45):12125-31. doi: 10.1002/anie.201407160. Epub 2014 Sep 22.
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.
人白细胞介素 6（IL-6）是一种具有免疫调节特性的强效细胞因子。由于 N-糖基化对 IL-6 的体内活性的影响迄今尚未阐明，因此通过顺序的天然化学连接建立了 IL-6 同质糖型的半合成。IL-6 的四个半胱氨酸适合连接，仅需要短的合成糖肽 43-48。Cys-肽 49-183 可以通过 SUMO 标签的切割重组获得。片段 1-42 可通过同时切割两个内含肽获得，导致具有天然 N 末端的 1-42 硫酯。连接和复性研究表明，固有不稳定的 Asp-Pro 键 139-140 不利于顺序从 C 末端到 N 末端的连接。使用糖肽酰肼的反向连接序列得到全长的 IL-6 糖蛋白，在有效复性和纯化后显示出完全的生物活性。
