Isolation and characterization of Vicia faba lectin affinity purified on chitin column

A lectin from early long pod var. of Vicia faba seed has been purified to homogeneity on chitin. The purified lectin is shown to be homogeneous in nature by Bio Gel P - 150 gel filtration, fast protein liquid chromatography and polyacrylamide gel electrophoresis. The lectin is a glycoprotein with molecular weight of 51,000. The lectin molecule is possibly composed of two types of subunits devoid of any covalent linking through sulfhydryl groups, with molecular weights 9,000 and 15,000 respectively in the ratio 2:2. The purified lectin shows a high affinity for N-acetyl-D-glucosamine (GlcNAc). Amino acid analyses show that cysteine and methionine are absent, and a high proportion of aspartic acid and glutamic acid are present in the protein molecule. The extinction coefficient of the purified lectin is 7.22. The lectin behaves as a 'cold agglutinin' displaying stronger agglutination than the naturally occurring ABO agglutinin in the cold.