A comparative study on the purification of the Amaranthus leucocarpus syn.Hypocondriacus lectin

Amaranthus leucocarpus lectin is a homodimeric glycoprotein of 35 kDa per s ub-unit, which interacts specifically with N-acetylgalactosamine. In this w ork, we compared different glycoproteins that contain Gal beta 1-3 GalNAc a lpha 1-3 Ser/Thr or GalNAc alpha 1-3 Ser/Thr in their structure as ligands to purify the A. leucocarpus lectin. From the glycoproteins tested, fetuin was the most potent inhibitor of the hemagglutinating activity and the bett er ligand for lectin purification; however, the use of desialylated stroma from erythrocytes represented the cheapest method to purify this lectin O-l inked glycans released from the glycoproteins used as affinity matrix and t hose from different erythrocytes were less inhibitory than parental glycopr oteins. The NH2-terminal of the lectin is blocked; moreover, this is the on ly example of a lectin isolated from this genus to be a glycoprotein. Analy sis of the glycoprotein sequences with inhibitory activity for the lectin, showed a different pattern in the O-glycosylation, which confirms that A. l eucocarpus lectin recognizes conformation and, probably, distances among O- linked glycans moieties.