Purification and Characterization of a Lectin of the Swartzieae Legume Taxa

Andreia      Varmes Fernandes; Marcio      Viana Ramos; Ilka      Maria Vasconcelos; Ana      Cristina Oliveira Monteiro Moreira; Frederico      Bruno Moreno; Jose      Odair Pereira; Jose      Francisco de Carvalho Goncalves

Abstract

This work aimed at describing the first biochemical and structural data of a lectin belonging to Swartzieae, a primitive Legume Taxa. A lactose-binding seed lectin (SLL) was purified by affinity chromatography of crude saline extracts of Swartzia laevicarpa on immobilized lactose. The SLL agglutinated rabbit erythrocytes but not rat or human (A, B, O) erythrocytes. Lectin activity was retained after heating at 100 °C for 15 min and was best inhibited by Nacetylgalactosamine, lactose and galactose. The lectin exhibited a single electrophoretic pattern that corresponded to a molecular mass of 29,000 Da, which was confirmed by MS analysis. In addition, the lectin reacted positively with Schiff’s reagent. The unique N-terminal amino acid sequence (39 residues) and the internal peptide sequence were determined by Edman degradation and MS/MS, respectively. The sequencing revealed complete homology of the SLL with legume lectins belonging to primitive groups (Dalbergieae and Sophoreae). The SLL (at 1 mg/ml) did not exhibit antifungal activity against various phytopathogens or cytotoxicity (at 100 μg/ml) towards different cancer cell lines.

Keywords: Amino acid sequence, lectin homology, Sophora japonica, lactose-binding seed lectin (SLL), affinity chromatography, erythrocytes, Edman degradation, peptide sequence