A De Novo Chemoenzymatic Assembly Strategy Enables the Efficient Preparation of a Large Core-Xylosylated N-Glycan Library for Probing Antibodies Against Schistosoma japonicum.

Core-xylosylated N-glycans represent a ubiquitous class of N-glycans widely distributed across nature. Recently, core-xylosylated N-glycans have attracted considerable attention in the medical field, as they could elicit strong immune responses. Notably, antibodies targeting core-xylosylated N-glycans could kill Schistosoma in vitro, and thus process potentials for protecting host from Schistosoma infections. However, the structural complexity has posed significant challenges to access structure-defined core-xylosylated N-glycans. Here, a powerful synthetic platform enabling the efficient preparation of core-xylosylated N-glycans is described. The strategy is based on de novo biosynthetic pathways to efficiently generate a sufficient quantity of N-glycan core precursors, coupled with the use of a robust β1,2-Xylosyltransferase to install core xylose in a stereoselective and regioselective manner. This approach further leverages diversity-oriented synthesis to systematically construct a comprehensive core-xylosylated N-glycan library, encompassing a broad range of structurally diverse N-glycans through enzymatic extension strategy. With the glycan array made from this glycan library, we investigated the binding activities of the antibodies against Schistosoma japonicum, which has caused widespread infections in Asia. In addition to the synthetic breakthroughs, this work also provides an insightful understanding of the structure-function relationships of core-xylosylated N-glycans, which will advance the rational design of carbohydrate-based vaccine against Schistosoma infections.