Purification, Characterization and Antitumor Activity of Rana nigromaculata Lectin

The lectin from Rana nigromaculata eggs was isolated by Sephadex G-75 gel filtration, DEAE-cellulose and Hydroxylapatite column chromatography. Isolated lectin was obtained in a homogeneous state by polyacrylamide gel electrophoresis (PAGE), and characterized as a basic protein with a molecular weight of 15500 by SDS-PAGE and an isoelectric point of pH 9.6 by isoelectric focusing. Amino acid analysis revealed threonine, aspartic acid, serine and qlutamic acid to be the predominant amino acids, the basic amino acids were relatively little. The isolated lectin strongly agglutinated cancer cells from experimental animals. The minimum agglutinating dose of lectin was 2.0 μg/0.2 ml for Ehrlich ascites carcinoma cells and 0.5 μg/0.2 ml for ascites hepatoma 109A cells. Agglutination it was specifically inhibited by ganglioside of human erythrocytes. This lectin strongly inhibited the growth of ascitic Ehrlich carcinoma while it was less active against the solid type.