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

  • Org Biomol Chem. 2016 Nov 29;14(47):11106-11116. doi: 10.1039/c6ob01982j.
Zhigang Wu  1 ,  Yunpeng Liu  1 ,  Cheng Ma  1 ,  Lei Li  1 ,  Jing Bai  2 ,  Lauren Byrd-Leotis  3 ,  Yi Lasanajak  4 ,  Yuxi Guo  1 ,  Liuqing Wen  1 ,  He Zhu  1 ,  Jing Song  1 ,  Yanhong Li  5 ,  David A Steinhauer  3 ,  David F Smith  4 ,  Baohua Zhao  2 ,  Xi Chen  5 ,  Wanyi Guan  6 ,  Peng George Wang  1
Affiliations
  • 1. Department of Chemistry and Center of Diagnostics & Therapeutics, Georgia State University, Atlanta, GA 30303, USA. [email protected].
  • 2. College of Life Science, Hebei Normal University, Shijiazhuang, Hebei 050024, China. [email protected].
  • 3. Departments of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA.
  • 4. Department of Biochemistry and Emory Comprehensive Glycomics Core, Emory University School of Medicine, Atlanta, GA 30322, USA.
  • 5. Department of Chemistry, University of California, Davis, CA 95616, USA. [email protected].
  • 6. Department of Chemistry and Center of Diagnostics & Therapeutics, Georgia State University, Atlanta, GA 30303, USA. [email protected] and College of Life Science, Hebei Normal University, Shijiazhuang, Hebei 050024, China. [email protected].
PMID: 27752690 DOI: 10.1039/c6ob01982j
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 (sLex) and Siaα2-8-Siaα2-3/6-R structures with N-acetylneuraminic acid (Neu5Ac) or N-glycolylneuraminic acid (Neu5Gc) sialic acid form, LacNAc, Lewis x (Lex), α-Gal, and Galα1-3-Lex; and tandem epitopes including α-Gal, Lex, Galα1-3-Lex, LacNAc, and sialyl LacNAc, presented with an internal sialyl LacNAc or 1-2 repeats of an internal LacNAc or Lex 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.

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