Purification of a Lectin from Amaranthus Leucocarpus by Affinity Chromatography

-A lectin of M, ca 45,000 per subunit from Amaranthus leucocarpus seeds, has been isolated and purified by affinity chromatography using a stroma column. It is a glycoprotein (10% w/w carbohydrate) containing six N-acetylD-glucosamines, four D-galactoses, one D-glucose and traces of xylose residues for each three D-mannose residues per molecule. Its amino acid composition reveals a predominance of acidic residues (aspartic and glutamic) and of glycine and alanine. In addition, the lectin contains an unusual amount of essential aminoacids such as methionine, tryptophan and lysine. Electrophoretically and chromatographically homogenous, it focuses as a multiple-band protein in the pH range of 4.8-5.2. It agglutinates the different human blood groups of the ABO system equally well, albeit being inhibited by N-acetyl-D-galactosamine in a specific fashion. In contrast to A. caudatus hemagglutinin A. leucocarpus lectin is inhibited by serum glycoproteins such as fetuin, it is mitogenic and is not toxic.