Structures of the asparagine-linked oligosaccharide chains of human von Willebrand factor. Occurrence of blood group A, B, and H(O) structures

Abstract

The asparagine-linked oligosaccharide chains of human von Willebrand factor (vWF) purified from pooled plasma were quantitatively liberated from the polypeptide moiety by hydrazinolysis. After N-acetylation, these were fractionated by paper electrophoresis and sequential chromatography on lectin-affinity columns of concanavalin A, Phaseolus vulgaris erythrophytohemagglutinin, Datura stramonium agglutinin, Ricinus communis agglutinin 120, and Ulex europaeus agglutinin I and on a Bio-Gel P-4 column. Their structures were investigated by sequential exoglycosidase digestion in conjunction with methylation analysis. The glycoprotein was shown to be unique in its great diversity of oligosaccharide structures. Another noteworthy finding which had not been reported previously was the occurrence of asparagine-linked oligosaccharide chains with blood group A, B, and H(O) structures. In the present study, this glycoprotein was shown to contain mono- (0.4% of the total oligosaccharides), bi-(78.2%), tri- (12.3%), and tetraantennary (2.3%) complex type oligosaccharides in addition to a series of high mannose type oligosaccharides, Man6-9GlcNAc2 (0.8%). Biantennary complex type oligosaccharide chains were those with (8.2%) and without (70.0%) a bisecting GlcNAc residue and approximately 13.2%, 2.2%, and 0.4% of these contained blood group H(O), A, and B structures, respectively. The tri- and tetraantennary complex type chains were those with and without N-acetyllactosamine repeats, and about 13.0% of the triantennary chains without the N-acetyllactosamine repeat contained the blood group H(O) structure. Occurrence of these asparagine-linked oligosaccharides with blood group A and B structures suggest that the repeated use of factor VIII/vWF pooled concentrate for the treatment of hemophiliacs could result in the production of antibodies against vWF with a different blood group from that of the patient, and this development may be pathogenic.