Caracterização bioquímica e estrutura primária da lectina de sementes de Pisum arvense L.

Abstract

Seeds of the leguminous plant Pisum arvense showed to contain a glicose/mannoseespecific lectin that was purified by affinity chromatography on Sephadex G-100 column. The purified lectin exhibit a native molecular weight of 50 kDa by analytical centrifugation. This value has been confirmed by SDS-PAGE, size exclusion chromatography on Supero se 12 HR/30 and Electron Spray Ionization (ESI) experiments. P. arvense lectin showed to be constituted oftwo distnct sub-units a e B, with a molecular mass of 5,591 and 19,986 kDa, respectively. The association of these sub-units led to form a dimer with the structural form of (aB)2. The amino acid composition of P . a r v e n s e lectin showed to be very similar those reported to the Vicieae tribe. The primary structure exhibited 100 % of homology with the lectin of the closely related species P. sativum. The dG' for the desnaturating process was 23 kcal/moI at 70°C and extinction coefficient of 14.8. The lectin was able to agglutinate almost at the same leveI native and enzyme-human blood groups ABO. The strongest agglutination was observed against rabbit native and enzyme treated erythrocytes. The lectin induced mitogenisis of human peripheral blood lymphocytes. Germination studies without light showed that the lectin is mobilized later when compared with other storage proteins.