The binding specificity of a second lectin purified from seeds of Bandeiraea simplicifolia (BS II) was studied by quantitative precipitin and inhibition assays. The lectin is not blood group specific and did not precipitate with A1, A2, Le(a) and a precursor blood group substance with I and i activity. Individual human B and H substances reacted to different extents due to their heterogeneity, those with terminal non-reducing αDGlcNAc reacting well; those lacking such residues did not precipitate. Glycoproteins with terminal βDGlcNAc such as agalactoorosomucoid also precipitated the lectin. Inhibition of precipitation showed phenyl αDGlcNAc and pNO2 phenyl αDGlcNAc to be the best inhibitors, while their β anomers were relatively inactive. Of the free sugars tested only DGlcNAc showed considerable activity; methyl αDGlcNAc was twice as good as DGlcNAc but only 1/3 as active as phenyl αDGlcNAc, while methyl βDGlcNAc was relatively inactive. DGlcNAcβ1→3 or β1→6 linked to DGal and DGlcNACβ1→3[DGlcNAcβ1→6]DGal were not active. DGlcNAcα1→4DGal was 80% as active as methyl αDGlcNAc; reduction of the DGal to galactitol reduced its activity greatly. The presence of a third sugar giving DGlcNAcα1→4DGalβ1→4DGlcNAc made it as active as methyl αDGlcNAc. N,N'-diacetylchitobiose, N,N',N''-triacetylchitotriose and N,N',N'',N'''-tetraacetylchitotetraose which were all equal and as active as methyl αDGlcNAc and DGlcNAcα1→4DGalβ1→4DGlcNAc. However, DGlcNAcα1→4DGalβ1→3DGalNAc had much lower activity. DGlcNAcα1→5DGlcf had the same activity as phenyl αDGlcNAc. To explain the unusual finding that α and β linked oligosaccharides of DGlcNAc were of comparable activity, molecular models were constructed. The best inhibitors showed a basic similarlity in three dimensional structure, the overall planarity of the molecule and hydrophobic interactions are of importance.
|Original language||English (US)|
|Number of pages||16|
|State||Published - 1978|
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