Characterization of a lectin from cowpeas.

A lectin without blood group specificity was isolated from cowpeas (Vigna unguiculata (L.) Walp.). This lectin was prepared from a crude saline extract by acid precipitation and Sephadex gel filtration. Purification steps generally resulted in increased agglutination activity. Homogeneity was demonstrated by polyacrylamide gel electrophoresis, and ultracentrifugation. The native lectin had a molecular weight of approximately 55,000 as shown by gel filtration, polyacrylamide electrophoresis, and analytical ultracentrifugation. Amino acid analysis showed a very low sulfur amino acid content and relatively high content of aspartic and glutamic acids. Total neutral sugar analysis indicated less than 1% of saccharides. The lectin interacted with several saccharides.