title: Chemoenzymatic Approach for the Preparation of Asymmetric Bi-, Tri-, and Tetra-Antennary N-Glycans from a Common Precursor.
abstract: Progress in glycoscience is hampered by a lack of well-defined complex oligosaccharide standards that are needed to fabricate the next generation of microarrays, to develop analytical protocols to determine exact structures of isolated glycans, and to elucidate pathways of glycan biosynthesis. We describe here a chemoenzymatic methodology that makes it possible, for the first time, to prepare any bi-, tri-, and tetra-antennary asymmetric N-glycan from a single precursor. It is based on the chemical synthesis of a tetra-antennary glycan that has N-acetylglucosamine (GlcNAc), N-acetyllactosamine (LacNAc), and unnatural Galα(1,4)-GlcNAc and Manβ(1,4)-GlcNAc appendages. Mammalian glycosyltransferases recognize only the terminal LacNAc moiety as a substrate, and thus this structure can be uniquely extended. Next, the β-GlcNAc terminating antenna can be converted into LacNAc by galactosylation and can then be enzymatically modified into a complex structure. The unnatural α-Gal and β-Man terminating antennae can sequentially be decaged by an appropriate glycosidase to liberate a terminal β-GlcNAc moiety, which can be converted into LacNAc and then elaborated by a panel of glycosyltransferases. Asymmetric bi- and triantennary glycans could be obtained by removal of a terminal β-GlcNAc moiety by treatment with β-N-acetylglucosaminidase and selective extension of the other arms. The power of the methodology is demonstrated by the preparation of an asymmetric tetra-antennary N-glycan found in human breast carcinoma tissue, which represents the most complex N-glycan ever synthesized. Multistage mass spectrometry of the two isomeric triantennary glycans uncovered unique fragment ions that will facilitate identification of exact structures of glycans in biological samples.
authors.affiliation: Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, and Bijvoet Center for Biomolecular Research, Utrecht University , Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.
authors.forename: Ivan A
authors.initials: IA
authors.lastname: Gagarinov
authors.forename: Tiehai
authors.initials: T
authors.lastname: Li
authors.affiliation: Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, and Bijvoet Center for Biomolecular Research, Utrecht University , Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.
authors.forename: Javier Sastre
authors.initials: JS
authors.lastname: Toraño
authors.affiliation: Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University , Padualaan 8, 3584 CH Utrecht, The Netherlands.|Netherlands Proteomics Centre , Padualaan 8, 3584 CH Utrecht, The Netherlands.
authors.forename: Tomislav
authors.initials: T
authors.lastname: Caval
authors.affiliation: Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, and Bijvoet Center for Biomolecular Research, Utrecht University , Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.
authors.forename: Apoorva D
authors.initials: AD
authors.lastname: Srivastava
authors.affiliation: Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, and Bijvoet Center for Biomolecular Research, Utrecht University , Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.
authors.forename: John A W
authors.initials: JA
authors.lastname: Kruijtzer
authors.affiliation: Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University , Padualaan 8, 3584 CH Utrecht, The Netherlands.|Netherlands Proteomics Centre , Padualaan 8, 3584 CH Utrecht, The Netherlands.
authors.forename: Albert J R
authors.identifier: 0000-0002-2405-4404
authors.initials: AJ
authors.lastname: Heck
authors.affiliation: Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, and Bijvoet Center for Biomolecular Research, Utrecht University , Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.
authors.forename: Geert-Jan
authors.identifier: 0000-0003-3111-5954
authors.initials: GJ
authors.lastname: Boons
mesh_terms: D000818:Animals; D006026:Glycoside Hydrolases / Q000138:chemical synthesis* / Q000737:chemistry; D006801:Humans; D011134:Polysaccharides / Q000737:chemistry*
chemical_list: D011134:Polysaccharides; D006026:Glycoside Hydrolases