Gomas endospérmicas de Delonix regia e Schizolobium parahybae: uso no isolamento de lectinas vegetais

Abstract

The isolation of lectins, seed proteins with the ability to interact with carbohydrate and glycoconjugates, is normally done by affinity chromatography on commercial polysaccharides of known composition as Sephadex, Sepharose and substituted agarose. The use of natural gums as matrices for these affinity chromatographies is poorly investigated. The gums, as galactomannans, have diverse proporions of galactose to mannose, that give to these glycoconjugates different susceptibility to interact with different lectins. Thus, the use of seed endospermic gums of Delonix regia, Parkinsonia aculeata and Schizolobium parahybae as matrices for affinity chromatography of lectins were investigated. In ordes to obtain the galactomannan, the seed coat and cotyledons, ground and freeze dried. The dry material was then treated with diferent concentrations of epychlorydrin in 3 N NaOH, and let to react (40°C, 12 h and 70°C, 24 h). The cross - linked gums, after washing and homogenation was used to prepare the column. The different cross - linked material obtained were tested with severa I lectins, with different specificity and only the lectins D-galactose specific showed affinity for the matrix. Thus, when crude extracts from seeds of Artocarpus integrifolia, Artocarpus incisa, Abrus precatorius and Abrus pulchellus were applied to the column, two fractions were obtained. One non-retained fraction, showed ali the activity that could be eluted with 0,2 M D-galactose. The purity of the peaks was demonstrated by SDS/PAGE. The efficiency and specificity of the differents gums were compared and it was observed that, although ali of then were able to isolate D-galactose specific lectins. Their efficiency were different, probably due to the differences of in their fine structure of the galactomannas.