-LACTOSE BINDING HEMAGGLUTININS FROM THE ASCIDIAN PHALLUSIA MAMILLATA (CUV.)

¹ Zoological Institute, Palermo University, Via Archirafi, 18, 90123 Palermo, Italy

The carbohydrate binding specificities of Phallusia mamillata anti-rabbit and anti-human (A, B, O) hemagglutinins were determined by hemagglutinin inhibition tests. Both these molecules bind -lactose, while only anti-HE hemagglutinins bind lactulose. In spite of this difference, absorption experiments did not show two distinct agglutinins for rabbit and human erythrocytes. Since both sugars are oligosaccharides which present a D-galacto-configuration, isolation by affinity chromatography with Sepharose was performed. The D-galactose-eluted fraction, investigated by PAGE and SDS-PAGE, appears to be the more anodal serum glycoprotein which consists of 2 subunits: the larger has a molecular weight of approximately 61-65,000 Daltons and the second one was 4000 Daltons smaller than the first. Gel filtration on Sephadex G 200 suggests that hemagglutinins represent a population of molecules in which the larger molecules (<200,000 Daltons) represent the greatest fraction.