Purification, Characterization and Antitumor Activity of Rana nigromaculata Lectin

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Abstract
The lectin from R. 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 by SDS[sodium dodecyl sulfate]-PAGE and isoelectric focusing. The lectin is a basic protein with a MW of 15,500 and an isoelectric point of pH 9.6. Amino acid analysis revealed threonine, aspartic acid, serine and glutamic acid to be the predominant amino acids; there were relatively little basic amino acids. The isolated lectin strongly agglutinated cancer cells from experimental animals. The minimum agglutinating dose of lectin was 2.0 .mu.g/0.2 ml for [mouse] Ehrlich ascites carcinoma cells and 0.5 .mu.g/0.2 ml for ascites [mouse] hepatoma 109A cells. Agglutination was specifically inhibited by ganglioside of human erythrocytes. This lectin strongly inhibited the growth of ascitic Ehrlich carcinoma; it was less active against the solid type.