A new mitogenic D-galactosephilic lectin isolated from seeds of the coral-tree Erythrina corallodendron. Comparison with Glycine max (soybean) and Pseudomonas aeruginosa lectins

Abstract

The lectin of E. corallodendron (Caesalpiniaceae) seeds was purified by heating, (NH4)2SO4 fractionation and affinity chromatography on acid-treated Sepharose. The purified lectin is similar to the soybean lectin in being a glycoprotein of MW 110,000-120,000 and having D-galactosephilic activity. This lectin, like the soybean and P. aeruginosa lectins, binds to D-galactosamine, N-acetyl-D-galactosamine, .alpha.- and .beta.-D-galactosides and to D-galactose. Like these lectins it adsorbs onto either untreated or enzyme (papain or neuraminidase) treated human red blood cells, but exhibits a considerable mitogenic activity towards human lymphocytes (predominantly T cells) only after their treatment with neuraminidase. This mitogenic stimulation of lymphocytes is inhibited by D-galactose and its derivatives. Despite the great similarity between them, the E. corallodendron, soybean and Pseudomonas lectins differ in regard to the intensity of their agglutinating activity towards erythrocytes obtained from different animals and human donors of diverse ABO blood groups. This phenomenon may be attributed to the difference in the affinities of the 3 lectins to the various D-galactose derivatives and to their molecular properties.