Lectins are widespread in nature and most of them have been isolated and characterized from Leguminoseae, Gramineae and Labiatae families. Preliminary experiments have shown lectin activity in crude extracts from seeds of Calopogonium galactoides (tribe Glycininae, family Leguminoseae). Therefore this work focused on purification and characterization of a novel lectin from Calopogonium galactoides which recognizes A group red blood cells (RBC). The assays were carried out using mature seeds, the crude extract was obtained using PBS-Thiourea 5 mM and fractional precipitation with ammonium sulphate (10% - 80%). The protein was purified on DEAE–Cellulose, Sephacryl S-200 and, finally on Mannose-Sepharose by eluting retained fraction with a-methyl mannopiranose 0,2 M or mannose 0,2 M. 1,4 mg of pure protein was obtained from 2 g of seeds. Some lectin´s molecular properties were determined and inhibition tests were carried out using a set of carbohydrates. The hemagglutination was inhibited by mannose and N-acetyl galactosamine; the specific titer using A human RBC was 0.09 ug/ul. SDS-PAGE profile showed four major bands around 20 kDa, 29 kDA, 41 kDa and 52 kDa and the isoelectric point (PI) showed bands in the acidic region between at pH from 4.9 to 6.4. With these studies we gave a step forward into this topic and the knowledge of new lectins that can be used to recognize carbohydrates or tumoral markers and our next aim is to carry out structural studies on calopogonium lectins in order to find out lectin-carbohydrate interactions. To date this field is unexplored.
[1] Alvarado R. C., 2012, BSc final work, unpublished.
[2] Lee J. et al 2001, American Journal of Botany 88(11): 2064–2073.
Key words: Calopogonium lectin, glycoconjugate, carbohydrates, A antigen, tumoral marker.
