ABSTRACT
The present investigation deals with the isolation and characterization of a lectin from Aedes aegypti (Ae aegypti) female mid gut extract that agglutinates various mammalian red blood cells (RBCs) such as human three groups A, B, and O (RH+), mouse, rat, guinea-pig, sheep and goat erythrocytes. The highest activity of both crude and isolated mid gut lectins were detected against sheep RBCs. Using (NH4)2 SO4 fractionation, ion-exchange and mannose-CNBr-Sepharose 6B affinity chromatography techniques, Ae. aegypti midgut lectin (Aelec) was purified to homogeneity.Isoelectric focusing (IEF) and reducing SDS/PAGE revealed that the isolated mid gut lectin had isoelectric point (PI) of 5.90, and subunits approximate molecular weights of 35.50 and 27.35 KDa. The hemagglutination (HA) of lectins were Ca2+ - independent and heat-resistant. The sugar specificity of the purified Aelec was strongly inhibited by D (+)-mannose and raffinose, followed by D (+) glucose. N-acetyl-D-manosamine and N-acetyl-D-glucosamine were moderate inhibitors. None of the lectins were inhibited by the disaccharides such as galactose, lactose, trehalose (IC50 up to 200 mM or fetuin up to 1%) but the glycosubstances mucin and laminarin were strong inhibitors up to very low concentrations (0.030 - 0.003%).
Key words:
Lectin; purification; characterization; hemagglutination; Aedes aegypti; mosquitoes
