Lectinas de sementes de Parkia panurensis e de Parkia biglobosa: estudos físico-químicos e estruturais

Abstract

Lectins are proteins of non-immune origin with at least one non-catalytic domain that reversibly binds to specific mono or oligo saccharides and are widely distributed in the plant kingdom. These lectins are presented as valuable tools for biotechnological byplay important biological functions such as recognition of cancer cells, mitogenic agents, immune suppressants among others. In this work, it was isolated lectin from Parkia panurensis seed (Ppal) specifies to mannose and glucose by combining the techniques of ammonium sulfate fractionation and affinity chromatography on a sepharose-mannose column. The analysis of the physicochemical properties showed that Ppal can maintain its hemagglutination activity at a wide range of temperature and pH and also was dependent of metal ions Ca2+and especially Mn2+. By the electrophoresis (SDS-PAGE) analysis, the Ppal showed an electrophoretic profile composed of dual band, higher molecular weight approximately 45kDaand a smaller molecular weight of approximately30kDa. Studies to determine the three-dimensional structure of Parkia biglobosa seed lectin (PBL) showed the complete crystal structure of PBL complexed withα-methyl-manosídeo consists of a monomer in the asymmetric unit consists of threeβ-prism domains with homologous amino acid sequences arranged in tandem. The structure of the monomer has three carbohydrate binding sites, each binding site to carbohydrates is located in one of theβ-prism domains. All ligands showed different patterns of interaction with the residues of the carbohydrate binding site.