Lectins of <i>Erythrina poeppigiana</i> and <i>Erythrina steyermarkii</i> (Leguminosae): charaderization and mitogenic effect

Abstract

Erythrina species are widely distributed in Costa Rica and known popularly as "poró". In this study, two species were selected, Erythrina poeppigiana and Erythrina sreyermarldi. Seed extracts were prepared in phosphate-buffered saline. The presence of lectins in the extracts was verified by hemagglutinating effect over suspensions of human erythrocytes. A selective hemagglutinating effect on erythrocytes of severa! marnmal species, goat, horse and rabbit red cells was tested; only the latler were agglutinated by E. sreyermarkii. The hemagglutinating effect of both lectins was inhibited with the following carbohydrates: D-galactose, N-acetyl galactosamine, D-Iactose and D-raffinose. The lectin from E. sreyermarkii was also inhibited with L-rhamnose. Both lectins were isolated with gel filtration and affinity chrornatography using lactose as ligand. Fractions that proved positive were tested with the sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Gel filtration and SDS-PAGE showed that these lectins have an apparent molecular mass of 50kDa, and are formed by two subunits of approximately 25 kDa. E. poeppigiana had no mitogenic effect, but the extraet of E. steyermarkíi had a mitogenic effect on human mononucJeat cells isolated from peripheral blood. The stability of the lectins was tested at different temperature and pH ranges (4 to 100 oC) and at pH 2 to 12. 80th were stable al a pH range: from 2 to 10, and at temperatures from 40 to 70 oC.