Lectins are widespread in nature and most of them have been isolated and characterized from Leguminoseae, Gramineae and Labiatae families; the last one, signalled their ability to recognize the Tn antigen (GalNAc-α-O-Ser(Thr)) [1], normally a cryptic structure in the peptide core of O-glycoproteins and which is widely expressed in several tumours. To date, a few lectins have been described that specifically recognized Tn antigen [1]. Otherwise very few have been purified and characterized because of the low amount in the seeds also the purification processes do not produce a good yield. Therefore this work focused on purification and characterization of a lectin from Salvia rubescens seeds (SRb) which recognizes aBSM by ELLSA assay with a high percentage of activity in order to get a new lectin for working on the elucidation of the primary and tertiary structure; to date is not known from any lectin structure Lamiaceae. Preliminary assays were carried out using mature seeds, the crude extract was obtained using PBS-5 mM Thiourea; after that it was subjected to fractional precipitation with ammonium sulphate (0-40%s, 40-80%s) and ethanol (0-60%), the last procedure showed the best results. The protein was purified on DEAE –Sephadex and after that affinity chromatography on desialylated bovine submaxilar mucin (aBSM)-Sepharose 4B by eluting it at pH 11.4 [2]. A band around 25 kDa was shown by SDS-PAGE, the carbohydrate contents was determinated and the ability to agglutinate enzimatically treated erythrocytes (Tn) was proved and the minimum required lectin concentration. With these studies we gave a step forward into this topic and the knowledge of new tools that can be used to recognize tumoral markers.
Key words: lectin, glycoconjugate, carbohydrates, Tn antigen, tumoral marker.
[1] Pérez, G.; Vega, N. Functional Plant Sci. Biotechnol. (2007). 1, 288-299.
[2] Vega, N. y Pérez, G. (2006). Phytochemistry, 67, 347-355.
