Isolamento, purificação, caracterização parcial e atividade biológica de uma lectina de sementes de Lonchocarpus sericeus (Leguminosae-Papilionoideae-tribo Tephrosieae)

Abstract

Lectins form a diverse group of proteins that has in common the ability to recognize specifically carbohydrates. LsL is a lectin present in Lonchocarpus sericeus seeds that was isolated and purified by affinity chromatography on chitin column followed by ionic exchange chromatography on Mono-Q column, monitored by a HPLC system. PAGE-SDS revealed a protein band with an apparent molecular mass of 25 kDa that was further confirmed by mass spectrometry. LsL activity was inhibited bya-Methyl-D-glucopyranoside and N-acetylglucosamine, rich in asparagine/aspartic acid, acid glutamine/glutamic acid and leucine amino acid residues, and it does not present residues of cystein and tyrosin. LsL was capable to inhibit the growth of the gramnegative bacteria (X anthom onas axonopodis pv. passiflorae), a plant pathogenic microorganism that wounds the P assiflora plant (passion fruit), probably by biding to the bacterial membrane. The reduction of leukocytes, neutrophyl migration, activity of the adenosine deaminase (ADA) and the decrease in the bacteria number were induced by LsL in the model of induced infectious peritonitis in rats. This effect also seems to be mediated by the carbohydrate-binding site domain, since the previous association of the lectin with its specific sugar (N-acetylglucosamine), partially reverted the effect on the neutrophyl migration and activity of the ADA in peritoneal cavity.