Isolation and characterization of a novel lectin from Dioclea lehmanni (Fabaceae) seeds

Dioclea lehmanni seeds are known to contain two lectins [G. Pérez, M. Hernández, E. Mora, Isolation and characterization of a lectin from the seeds of Dioclea lehmanni, Phytochemistry 29 (1990) 1745-1749]. Taking advantage of the strong bond shown by one of them (Dioclea lehmanni lectin I) to Sephacryl S-200, it has been purified and characterized as a Glc/Man lectin very similar to Concanavalin A. In order to compare the properties of the two lectins, we purified the second one (Dioclea lehmanni lectin II) to homogeneity by gel filtration and hydrophobic chromatography. Dioclea lehmanni lectin II is a dimeric protein (58.4 kDa) with identical subunits with M(r) = 29,000. Its molecular properties, carbohydrate specificity, human and animal erythroagglutination pattern, amino acid composition and N-terminal sequence (27 residues) were determined. These features clearly distinguish lectin II from lectin I; therefore a second novel lectin is present in the seeds of Dioclea lehmanni.