Purification, Partial Characterization, and CNBr-Sepharose Immobilization of a Vasorelaxant Glucose/Mannose Lectin from Canavalia virosa Seeds

A novel mannose/glucose-binding lectin from Canavalia virosa (designated as ConV) has been purified from seeds of C. virosa by affinity chromatography on a mannose-Sepharose 4B column. ConV strongly agglutinates rabbit erythrocytes and was inhibited by monosaccharides (D-mannose, D-glucose, and alpha-methyl-D-mannoside) and glycoproteins (ovalbumin and fetuin). SDS-PAGE revealed three bands corresponding to three subunits (alpha, beta, and gamma) confirmed by ESI mass spectrometry with exact mass of 25,480 +/- 2 Da, 12,864 +/- 1 Da, and 12,633 +/- 1 Da, respectively. The purified lectin was more stable in pH ranging from 7.0 to 9.0, supported up to 80 A(0)C without any loss in activity and unaffected by EDTA. ConV showed no toxicity against Artemia sp. nauplii and relaxed endothelized rat aorta, with the participation of the lectin domain. In our tests, the lectin immobilized on CNBr-Sepharose was capable of binding 0.8 mg of ovalbumin per chromatography, allowing the use of ConV as a tool for capture and purification of glycoproteins.