Purification and Identification of a Natural Lectin from the Seed of Peanut Arachis hypogaea

A natural lectin from the seed of peanut Arachis hypogaea was purified by singlestep affinity chromatography using galactoside-coupled agarose. The native molecular mass of purified A. hypogaea lectin (PN-L) was 29 kDa. The lectin PN-L was detected for agglutinating activity, glycoinhibiting action and thermostability. The influence of pH on those activities was also tested. The results showed that PN-L could not agglutinate three kinds of human erythrocytes. But it showed a strong affinity to human A, B and O erythrocytes (RBC) treated by neuraminidase. Agglutinating activity of PN-L to neuraminidase treated human O erythrocytes was inhibited by lactose, raffinose, melibiose and D-galactose. The agglutinating activity of peanut seed lectin was stable up to 55°C and at pH 5.0-11.0. The results of MALDI-TOFTOF analysis indicated that the protein PN-L showed highly homology with the Peanut Lectin Chain A protein (gi|1942899).