Identification of the binding roles of terminal and internal glycan epitopes using enzymatically synthesized N-glycans containing tandem epitopes

Zhigang Wu; Yunpeng Liu; Cheng Ma; Lei Li; Jing Bai; Lauren Byrd-Leotis; Yi Lasanajak; Yuxi Guo; Liuqing Wen; He Zhu; Jing Song; Yanhong Li; David A. Steinhauer; David F. Smith; Baohua Zhao; Xi Chen; Wanyi Guan; Peng George Wang

doi:10.1039/C6OB01982J

Identification of the binding roles of terminal and internal glycan epitopes using enzymatically synthesized N-glycans containing tandem epitopes†

Zhigang Wu,^a Yunpeng Liu,^a Cheng Ma,^a Lei Li,^a Jing Bai,^b Lauren Byrd-Leotis,^c Yi Lasanajak,^d Yuxi Guo,^a Liuqing Wen,^a He Zhu,^a Jing Song,^a Yanhong Li,^e David A. Steinhauer,^c David F. Smith,^d Baohua Zhao,^b Xi Chen,‡*^e Wanyi Guan*^ab and Peng George Wang*^a

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* Corresponding authors

^a Department of Chemistry and Center of Diagnostics & Therapeutics, Georgia State University, Atlanta, GA 30303, USA
E-mail: pwang11@gsu.edu

^b College of Life Science, Hebei Normal University, Shijiazhuang, Hebei 050024, China
E-mail: guanwanyi@mail.hebtu.edu.cn

^c Departments of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA

^d Department of Biochemistry and Emory Comprehensive Glycomics Core, Emory University School of Medicine, Atlanta, GA 30322, USA

^e Department of Chemistry, University of California, Davis, CA 95616, USA
E-mail: xiichen@ucdavis.edu

Abstract

Glycans play diverse roles in a wide range of biological processes. Research on glycan-binding events is essential for learning their biological and pathological functions. However, the functions of terminal and internal glycan epitopes exhibited during binding with glycan-binding proteins (GBPs) and/or viruses need to be further identified. Therefore, a focused library of 36 biantennary asparagine (Asn)-linked glycans with some presenting tandem glycan epitopes was synthesized via a combined Core Isolation/Enzymatic Extension (CIEE) and one-pot multienzyme (OPME) synthetic strategy. These N-glycans include those containing a terminal sialyl N-acetyllactosamine (LacNAc), sialyl Lewis x (sLe^x) and Siaα2–8-Siaα2–3/6-R structures with N-acetylneuraminic acid (Neu5Ac) or N-glycolylneuraminic acid (Neu5Gc) sialic acid form, LacNAc, Lewis x (Le^x), α-Gal, and Galα1–3-Le^x; and tandem epitopes including α-Gal, Le^x, Galα1–3-Le^x, LacNAc, and sialyl LacNAc, presented with an internal sialyl LacNAc or 1–2 repeats of an internal LacNAc or Le^x component. They were synthesized in milligram-scale, purified to over 98% purity, and used to prepare a glycan microarray. Binding studies using selected plant lectins, antibodies, and viruses demonstrated, for the first time, that when interpreting the binding between glycans and GBPs/viruses, not only the structure of the terminal glycan epitopes, but also the internal epitopes and/or modifications of terminal epitopes needs to be taken into account.

Organic & Biomolecular Chemistry

Identification of the binding roles of terminal and internal glycan epitopes using enzymatically synthesized N-glycans containing tandem epitopes†

Abstract

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Identification of the binding roles of terminal and internal glycan epitopes using enzymatically synthesized N-glycans containing tandem epitopes

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