Further definition of the size of the blood group-i antigenic determinant using a chemically synthesised octasaccharide of poly-N-acetyllactosamine type.
In earlier studies, the minimum structure which inhibited the binding of anti-i to an i-active glycoprotein was the linear trisaccharide, beta-D-Galp-(1----4)-beta-D-GlcpNAc-(1----3)-D-Gal. There was an increasing hierarchy of inhibitory activities in the linear tetrasaccharide, beta-D-Galp-(1----4)-beta-D-GlcpNAc-(1----3)-beta-D-Galp-(1----4)-beta-D -GlcNAc , its methyl beta-glycoside, and in the methyl beta-glycoside of the hexasaccharide. The linear octasaccharide methyl beta-glycoside in this series is approximately only half as active as the hexasaccharide methyl beta-glycoside. Analyses by high resolution 1H-n.m.r. of these two oligosaccharides indicated that they have similar conformations in solution, and there is no evidence for the occurrence of inter-molecular interactions which might partially hinder the binding of anti-i to the octasaccharide methyl beta-glycoside. These results are consistent with the size of the i antigen being in the region of a hexasaccharide. It is proposed that the methyl aglycon group of the hexasaccharide methyl beta-glycoside confers an above normal activity by presenting a hydrophobic area for additional contact in the vicinity of the antibody-combining site.
Feizi
T
T
Glycoconjugates Section, Clinical Research Centre, Harrow, Middlesex, United Kingdom.
Hounsell
E F
EF
Alais
J
J
Veyrières
A
A
David
S
S
D002240:Carbohydrate Sequence; D000939:Epitopes / Q000276:immunology*; D006023:Glycoproteins / Q000276:immunology*; D006801:Humans; D007048:I Blood-Group System / Q000276:immunology*; D009682:Magnetic Resonance Spectroscopy; D008470:Meconium / Q000737:chemistry; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000494:pharmacology*; D011134:Polysaccharides / Q000494:pharmacology*
D000939:Epitopes; D006023:Glycoproteins; D007048:I Blood-Group System; D009844:Oligosaccharides; D011134:Polysaccharides; C037199:poly-N-acetyllactosamine