Forssman pentasaccharide and polyvalent Ga1 beta 1 -> 4GlcNAc as major ligands with affinity for Caragana arborescens agglutinin

The binding properties of Caragana arborescens agglutinin (CAA, pea tree ag glutinin) were studied by enzyme linked lectinosorbent assay (ELLSA) and by inhibition of CAA-glycan interaction. Among glycoproteins (gps) tested, CA A reacted strongly with asialo bird nest gp, asialo rat sublingual gp, huma n Tamm-Horsfall Sd(a(+)) urinary gp (THGP) and asialo THGP that are rich in GalNAc alpha 1-->, GalNAc beta 1--> and/or Gal beta 1 --> 4GlcNAc residues . CAA also bound tightly with multivalent Gal beta 1 --> 4GlcNAc (mII) cont aining glycoproteins (human blood group precursor gps, asialo fetuin) and a sialo ovine salivary glycoprotein (Tn, GalNAc alpha 1 --> Ser/Thr) but CAA reacted poorly of not at all with sialylated glycoproteins tested, Of the s ugars tested for inhibition of binding, Forssman pentasaccharide (F-p, GalN Ac alpha 1 --> 3GalNAc beta 1 --> 3Gal alpha 1 --> 4Gal beta 1 --> 4Glc) wa s the best, It nas about 2.3, 9.5 and 52.6 times more active than Gal beta 1 --> 4GlcNAc, GalNAc and Gal, respectively, and about 1.9 times more activ e than tri-antennary Gal beta 1 --> 4GlcNAc (Tri-II), These results suggest that this agglutinin is mainly specific for F-p, mil and Tn clusters. This property can be used to detect human abnormal glycotopes related to F-p an d unmasked mII/Tn clusters and to study cell growth and differentiation giv en the lack of toxicity of this lectin toward mouse fibroblast cells, (C) 1 999 Federation of European Biochemical Societies.