CROSS-LINKING TREATMENT FOR INCREASING LECTIN-BINDING CAPACITY OF A VESICULAR AFFINITY SORBENT CONSISTING OF HIGHER-PLANT CELL-WALLS

The vesicular packing material (VP) prepared from cell walls of a susp ension culture of Chenopodium album was modified to increase its bindi ng capacity for galactose-specific lectins. Partial depolymerization o f pectin was accompanied by an increase in lectin binding capacity (LB C) per g dry sorbent irrespective of whether this process was caused b y a treatment at high pH (2% sodium carbonate, pH ca 11) and moderate temperature (25-40 degrees) or by a heat treatment (100 degrees) at pH 7 or 8. Therefore, depolymerization, not de-esterification of pectin, seems to be essential fdr the increase of the LBC. Because of its hig h LBC, the VP material treated for 2 hr with 2% sodium carbonate at 35 degrees (Vp2(35)) was selected for further modification. If this mate rial was dried from an alcohol and the obtained shrunken particles wer e incubated for some hours at room temperature in acetone or another h ydrophilic organic medium containing a mineral acid, the swelling of t he particles at subsequent equlibration with water was irreversibly re duced due to cross-linking of the folded walls, probably by the format ion of ester bonds. An optimized cross-linking treatment of Vp2(35) Wi th acetone containing 2% HCl caused an increase of the LBC per bed vol ume of the packed material, which resulted both from the decrease of t he bed volume and additional increase of the LBC per g dry material. T his treatment largely improves the properties of the VP2(35) as an aff inity sorbent for galactose-specific lectins.