Isolation and partial characterization of a mitogenic lectin from Lathyrus odoratus seeds

A mitogenic lectin has been isolated from saline extract of Lathyrus odoratus seeds by (NH4)2SO4 precipitation and subsequent chromatography on DEAE-Sepharose and CM-Sepharose. The isolated lectin was almost homogeneous by SDS gel electrophoresis and gel filtration, but multiple bands were obtained on isoelectric focusing. The molecular weight, determined by gel filtration, was 37,000. Gel electrophoresis in the presence of SDS gave a molecular weight of 19,000, thus suggesting that the lectin is a dimer. It agglutinated human erythrocytes of the different ABO groups equally well. Human lymphocytes were exposed to the lectin or PHA, and the incorporation of thymidine was measured. Compared with PHA, which stimulated maximally in the concentration range of 0.25--1microgram/ml, the L. odoratus lectin had optimal activity at concentrations of 35 microgram/ml and higher.