Institut des Biomolécules Max Mousseron (IBMM), UMR 5247, Université de Montpellier, CNRS, Ecole Nationale Supérieure de Chimie de Montpellier, 8 Rue de l'Ecole Normale, 34296, Montpellier- cedex 5, France.
Key Laboratory of Organofluorine Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, P. R. China.
Chemistry. 2018 Dec 17;24(71):18981-18987. doi: 10.1002/chem.201803912. Epub 2018 Nov 26.
Protein glycosylation is the most complex post-translational modification process. More than 50 % of human cells proteins are glycosylated, whereas bacteria such as E. coli do not have this modification machinery. Indeed, the carbohydrate residues in natural proteins affect their folding, immunogenicity, and stability toward proteases, besides controlling biological properties and activities. It is therefore important to introduce such structural modification in bioengineered proteins lacking the presence of carbohydrate residues. This is not trivial as it requires reagents and conditions compatible with the protein's stability and reactivity. This work reports on the introduction of lactose moieties in two natural proteins, namely ubiquitin (Ub) and l-asparaginase II (ANSII). The synthetic route employed is based on the sulfur(VI) fluoride exchange (SuFEx) coupling of a lactose tethered arylfluorosulfate (Lact-Ar-OSO F) with the ϵ-NH group of lysine residues of the proteins. This metal-free click SuFEx reaction relies on the properties of the fluorosulfate employed, which is easily prepared in multigram scale from available precursors and reacts chemoselectively with the ϵ-NH group of lysine residues under mild conditions. Thus, iterative couplings of Lact-Ar-OSO F to Ub and ANSII, afforded multiple glycosylations of these proteins so that up to three and four Lact-Ar-OSO groups were introduced in Ub and ANSII, respectively, via the formation of a sulfamoyl (OSO -NH) linkage.
蛋白质糖基化是最复杂的翻译后修饰过程。超过 50%的人类细胞蛋白都发生了糖基化，而像大肠杆菌这样的细菌则没有这种修饰机制。事实上，天然蛋白质中的碳水化合物残基影响其折叠、免疫原性和对蛋白酶的稳定性，此外还控制着生物特性和活性。因此，在缺乏碳水化合物残基的生物工程蛋白中引入这种结构修饰是很重要的。这并不简单，因为它需要与蛋白质稳定性和反应性兼容的试剂和条件。本工作报道了在两种天然蛋白（即泛素（Ub）和 l-天冬酰胺酶 II（ANSII））中引入乳糖部分。所采用的合成路线基于乳糖连接的芳基氟硫酸盐（Lact-Ar-OSO F）与蛋白质赖氨酸残基的 ε-NH 基团之间的硫（VI）氟交换（SuFEx）偶联。这种无金属点击 SuFEx 反应依赖于所使用的氟硫酸盐的性质，它可以从可用的前体多克规模制备，并在温和条件下与赖氨酸残基的 ε-NH 基团选择性反应。因此，通过 Lact-Ar-OSO F 与 Ub 和 ANSII 的迭代偶联，使得这些蛋白质的糖基化程度得到提高，以至于在 Ub 和 ANSII 中分别引入了多达三个和四个 Lact-Ar-OSO 基团，通过形成磺酰胺（OSO-NH）键。
