Purification of a N-acetyl-D-galactosamine specific lectin from the orchid Laelia autumnalis.

From the pseudobulbs of the orchid L. autumnalis a lectin was purified on immobilized porcine mucin with A + H blood group substance. This lectin is a dimeric glycoprotein of M(r) 12,000 with an Sw,20 of 2.2, showing haemagglutinating activity directed mainly to human A1 desialylated erythrocytes. The lectin possesses sugar specificity for N-acetyl-D-galactosamine and also shows high specificity for glycoproteins containing the T (galactose beta 1,3GA1NAc alpha 1,0 Ser/Thr) or the Tn antigen (GalNAc alpha 1,0 Ser/Thr).