PURIFICATION OF LECTINS FROM ROBINIA-PSEUDOACACIA L ROOT-TIPS

The presence of lectins in Robinia pseudoacacia root-tip extracts was demonstrated by horse erythrocyte agglutination and aggregation of (ne o)glycoprotein-coated beads. Two lectins were purified from a crude pr otein extract by ion-exchange and affinity chromatography. A mixture o f lectins was obtained by cation-exchange chromatography on a CM-Trisa cryl column. Rabinia pseudoacacia root agglutinin II (RPrAII) was furt her purified by specific elution from a GalNAc-BSA-Sepharose-4B column . Material passing through the GalNAc-BSA-Sepharose-4B column was stil l active as determined by erythrocyte agglutination, and aggregated or osomucoid-coated beads, this material was further purified by affinity chromatography on an orosomacuoid-Sepharose-4B column. Elution with 5 0 mM HC1 at pH 1.5 led to the purification of the second lectin referr ed as Rabinia pseuctoacacia root agglutinin I (RPrAI). Biochemical ana lysis suggests that RPrAI is a heterodimer made up of M(r)29 000 and 3 1 000 subunits whereas RPrAII is a homodimer made up of M(r) 30 000 su bunits, and that both lectins are glycoproteins. N-terminal sequences were determined for both lectins and compared with those deduced from cDNA clones encoding bark and seed lectins. Our results suggest that r oot lectins are not strictly identical with, but closely related to th e Robinia pseudoacacia seed and bark lectins. (C) 1997 Elsevier Scienc e Ireland Ltd.