Lectins (haemagglutinins) in the haemolymph of Glossina fuscipes fuscipes: Isolation, partial characterization, selected physico-chemical properties and carbohydrate-binding specificities: Isolation, partial characterization, selected physico-chemical properties and carbohydrate-binding specificities

Glossina fuscipes fuscipes haemolymph contained agglutinins (lectins), titre range 2-11-2-18, against red blood cells (RBC) of human ABO(H) blood group with highest values detected against "AB" RBC. The use of protease- and neuraminidase-treated RBC in many cases increased titres whilst treatment with galactosidases or glucosidases caused decreased levels. Haemolymph adsorption with "O" RBC reduced titres against "O" and "AB" but to a lesser extent anti-A or -B activity indicating lectin heterogeneity. The carbohydrate-binding specificities for human RBC were directed towards N-acetylated and deoxy derivatives of glucose and/or galactose. In addition the haemagglutinins were reactive against some oligosaccharides, ribose, deoxymannose, deoxygalactose, xylose and xylan with certain of the RBC types. The agglutinins were glycoprotein in nature, thermo-labile, affected by storage, freezing and thawing treatments and exposure to a high dosage of γ-radiation, possessed limited disulphide and hydrogen bonds, and depended upon slightly acid to neutral conditions for optimum agglutination. The haemag-glutinins did not require the presence of divalent cations (Ca2+, Mn2+ or Cu2+ ions) for activity although an elevated concentration of Mg2+ ions resulted in increased endpoint titres. However heavy metal ions (Pb2+ and Fe2+) in the buffer lowered agglutinin levels. The intact lectin molecule had an isoelectric point of 6.2, a relative molecular weight of 710 kDa and comprised approx. 70 kDa subunits.