Branching mode in complex-type triantennary N-glycans as regulatory element of their ligand properties.
We address the question whether the two natural types of branching in complex-type triantennary N-glycans differ in ligand properties. Toward this end, we prepared the set of pergalactosylated undecasaccharides and derivatives with alpha2,3/6-sialylation by chemoenzymatic synthesis. Conjugation resulted in neoglycoproteins which were tested in assays with lectins/antibodies, cultured cells and animals. Solid-phase assays with galactoside-specific proteins (a plant toxin, galectins and an antibody fraction) disclosed that the branching mode did not significantly affect affinity. However, compared to previous studies under identical conditions increase in antennae number and presence of substitutions in biantennary N-glycans altered KD-values with differences between receptors. Neoglycoprotein binding to cells of eight human tumor lines was sensitive to N-glycan branching. Staining intensity revealed pronounced branch-mode-dependent differences in four cases. Biodistribution profiles in mice uncovered dramatic changes in clearance rates with prolonged serum presence associated with type II branching of sialylated N-glycans and markedly increased uptake of neoglycoproteins with type I-branched N-glycans into liver, spleen, heart and lungs. This part of the study is relevant for rational glycoengineering of pharmaproteins. In general, our study supports the concept to view details of N-glycan structure, here branching, as a means to modulate ligand properties.
Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig-Maximilians-University, Veterinaerstr. 13, 80539 Munich, Germany. Sabine.Andre@lmu.de
Sabine
S
André
Shuji
S
Kojima
Gislinde
G
Gundel
Roland
R
Russwurm
Xaver
X
Schratt
Carlo
C
Unverzagt
Hans-Joachim
HJ
Gabius
D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000737:chemistry; D006023:Glycoproteins / Q000138:chemical synthesis / Q000737:chemistry*; D006801:Humans; D037102:Lectins / Q000737:chemistry; D008024:Ligands; D008969:Molecular Sequence Data; D009369:Neoplasms / Q000737:chemistry; D011134:Polysaccharides / Q000138:chemical synthesis / Q000737:chemistry*; D015202:Protein Engineering / Q000379:methods*; D014018:Tissue Distribution
D006023:Glycoproteins; D037102:Lectins; D008024:Ligands; D011134:Polysaccharides