A lectin with some unique characteristics from the samta tomato

A lectin, with a molecular mass of 79 kDa, and with specificity toward rhamnose and O-nitrophenyl-β-d-galactopyranoside, was isolated from samta tomato fruits. The procedure entailed ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on CM-cellulose and gel filtration by fast protein liquid chromatography on Superdex 75. The lectin was unadsorbed on DEAE-cellulose but adsorbed on Affi-gel blue gel and CM-cellulose. The lectin was stable up to 70 °C. The lectin activity was potentiated by NaOH solutions (25–100 mM), but was reduced by 50 and 100 mM HCl solutions. The activity of the lectin was reduced in the presence of CaCl2, MgCl2 and ZnCl2, but was potentiated by 5 and 10 mM AlCl3 solutions. The lectin stimulated the mitogenic response in mouse splenocytes and inhibited human immunodeficiency virus-1 reverse transcriptase with an IC50 of 6.2 μM.