Solution structure of two xenoantigens: alpha Gal-LacNAc and alpha Gal-Lewis X.
Organ hyperacute rejection, a phenomenon occurring during discordant xenotransplantation, is due to the recognition of an oligosaccharide epitope by human xenoreactive natural antibodies. In addition to the alpha Gal(1-3)beta Gal(1-4)GlcNAc trisaccharide, a fucosylated structure, alpha Gal-Lewis X, has been shown to be recognized by the antibodies. Both the trisaccharide and the tetrasaccharide have been synthesized by chemical methods. A complete nuclear magnetic resonance characterization of the two compounds has been performed, including the measurements of two-dimensional nuclear Overhauser effect spectroscopy data. Molecular dynamics simulations were run for several ns in the presence of explicit water molecules. The combination of experimental and theoretical approaches revealed the effect of an additional fucose residue on the conformational behavior of the xenoantigen. This branched fucose strongly rigidifies the N-acetyllactosamine. The effect on the alpha Gal(1-3)Gal fragment is less marked. In the presence of fucose, the terminal alpha Gal residue can still adopt two different conformations, but the equilibrium populations are modified.
Corzana
Francisco
F
Centre de Recherche sur les Macromolécules Végétales, Joseph Fourier University, BP 53, F-38041 Grenoble cedex 9, France.
Bettler
Emmanuel
E
Hervé du Penhoat
Catherine
C
Tyrtysh
Tatyana V
TV
Bovin
Nicolai V
NV
Imberty
Anne
A
D015478:Antigens, Heterophile / Q000737:chemistry*; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry*; D012996:Solutions
D015478:Antigens, Heterophile; D009844:Oligosaccharides; D012996:Solutions