Immunochemical studies on the binding specificity of the blood group Leb specific lectin Griffonia simplicifolia IV

Abstract

The specificity of the Griffonia simplicifolia IV (GS-IV) lectin was studied by quantitative precipitin and quantitative precipitin inhibition assays. The lectin precipitated most strongly with a human H,Leb blood group substance and reacted strongly with an Lea and an A2 blood group substance with Leb activity. Because of the heterogeneity of the blood group glycoproteins, the lectin reacted to different extents with substances of the same blood group activity. Specific precipitates of lectin with blood group substances which reacted strongly were less soluble than with those which reacted weakly. By inhibition of precipitation of GS-IV with H,Leb blood group substance, the lectin is most specific for the Leb oligosaccharide lacto-N-difucohexaose I, Lacto-N-difucohexaose II, was about one-fourth as active on a molar basis and other difucosyl oligosaccharides were somewhat less active but were more potent than monofucosyl Lea and H active oligosaccharides. Fuc was inhibitory only at very high concentrations. The binding site of the GS-IV lectin appears most specific for difucosyl oligosaccharides. Although the most active is an Leb oligosaccharide, the site may prove not to be Leb specific.