[Isolation, purification and characterization of a lectin from the seed of Erythrina costaricensis (Leguminosae)]

A lectin was isolated from the crude extract prepared from the seeds of E. costaricensis. It was purified by gel filtration on Sephadex G-100 followed by DEAE-Sephadex A-50 chromatography. PAGE revealed only one protein band, while analytical isoelectric focusing revealed four bands. The protein is a dimer with M(r) 58kda not united by disulfide bridges. It is a glycoprotein with 6.5% of neutral sugars, stable at 70 degrees C and at a pH range between 2 to 10. The protein exhibited a non specific agglutination of human erythrocytes, nevertheless it differentiated between erythrocytes of animal origin, agglutinating those of rabbit and chicken and not those from horse, goat, sheep or rat. Galactose, N-acetyl-D-galactosamine, lactose and EDTA are inhibitors while Ca++ and Mn++ acted as activators of the agglutination. No change in the blood pressure was observed when the lectin was intravenously injected in rats.