Structure-activity profiles of complex biantennary glycans with core fucosylation and with/without additional alpha 2,3/alpha 2,6 sialylation: synthesis of neoglycoproteins and their properties in lectin assays, cell binding, and organ uptake.
The consideration of oligosaccharides and glycoconjugates as biopharmaceuticals is an emerging topic in drug design. Chemoenzymatic synthesis of N-glycans was performed to examine the influence of N-glycan core fucosylation on lectin-binding properties and biodistribution. As a first step in a systematic comparison of N-glycans, the core fucose moiety was chemically introduced into a complex-type biantennary heptasaccharide azide. After deprotection and attachment of a spacer, the terminal sections of the N-glycan were elongated enzymatically. Conversion of the amino group in the spacer to an isothiocyanate gave derivatives allowing convenient ligand attachment to bovine serum albumin (BSA). The resulting neoglycoproteins contained an average of 2.9-4.6 chains per carrier molecule. Relative to unsubstituted biantennary complex-type N-glycans, the core fucosylation appears to favor the extended orientation of the alpha 1,6-arm. This was deduced from an up to 5-fold alteration of affinity for lectins in solid-phase assays. Marked differences were also found for cell surface binding of cultured tumor cells, for staining of tumor cells in lung sections, and in organ distribution. In vivo, the alpha 2,6-sialylated neoglycoproteins showed a reduced serum half-life in mice relative to the alpha 2,3-sialylated isomer and the non-fucosylated congeners. These results support the notion that changing the shape of a glycan provides a promising strategy to optimize the affinity of protein-carbohydrate interactions. Overall, our study underscores the importance of chemoenzymatic synthesis to define the effect of chain orientation on the ligand properties of N-glycans.
Unverzagt
Carlo
C
Institut für Organische Chemie und Biochemie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany. carlo.unverzagt@uni-bayreuth.de
André
Sabine
S
Seifert
Joachim
J
Kojima
Shuji
S
Fink
Christian
C
Srikrishna
Geetha
G
Freeze
Hudson
H
Kayser
Klaus
K
Gabius
Hans-Joachim
HJ
D000818:Animals; D000911:Antibodies, Monoclonal; D001665:Binding Sites; D002240:Carbohydrate Sequence; D002286:Carcinoma, Ehrlich Tumor / Q000378:metabolism; D002417:Cattle; D004337:Drug Carriers; D005643:Fucose / Q000737:chemistry*; D037483:Galectin 1; D006023:Glycoproteins / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D006388:Hemagglutinins / Q000737:chemistry; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry; D008024:Ligands; D008175:Lung Neoplasms / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D019158:N-Acetylneuraminic Acid / Q000737:chemistry*; D028321:Plant Preparations; D010940:Plant Proteins; D011134:Polysaccharides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D011485:Protein Binding; D054790:Ribosome Inactivating Proteins, Type 2; D012710:Serum Albumin, Bovine; D013329:Structure-Activity Relationship; D014018:Tissue Distribution; D014118:Toxins, Biological / Q000737:chemistry; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D004337:Drug Carriers; D037483:Galectin 1; D006023:Glycoproteins; D006388:Hemagglutinins; D007074:Immunoglobulin G; D008024:Ligands; D028321:Plant Preparations; D010940:Plant Proteins; D011134:Polysaccharides; D054790:Ribosome Inactivating Proteins, Type 2; D014118:Toxins, Biological; C009674:ribosome inactivating protein, Viscum; D012710:Serum Albumin, Bovine; D005643:Fucose; D019158:N-Acetylneuraminic Acid