ESTIMATION OF FUNCTIONAL CARBOHYDRATE-BINDING LECTIN IN PEANUT TISSUES BY ENZYME-LINKED IMMUNOASSAY

A glycoprotein antibody sandwich enzyme-linked immunoassay (GAS ELISA) was used for the detection of functional galactose- and mannose-binding lectins (GL and ML, respectively) in the tissues of peanut (Arachis hypogaea L.) as an alternative to haemagglutination assay (HA). Selection of an appropriate glycoprotein receptor for each lectin was essential as nodule GL and seed GL differed in their respective GAS ELISA reactions with asialothyroglobulin. Their reaction with blood group substance A + H (BGS) was identical, however. Nodule ML and cotyledon ML did not differ in their ability to bind to either ovalbumin or transferrin. Use of the glycoproteins BGS and ovalbumin for the assay of GL and ML, respectively, allowed the detection of each lectin down to 30-80 ng/ml. This was less sensitive than the double antibody sandwich (DAS) ELISA (2 ng/ml) but more sensitive than HA (400 mug/ml). Estimates of GL and ML in peanut tissues by GAS ELISA were comparable to those obtained by DAS ELISA but HA appeared to overestimate ML concentrations.