Isolation of a Hemagglutinating γ-conglutin from Seeds of the Andean Legume Lupinus mutabilis Sweet (Tarwi)

Abstract

Background: Lupinus mutabilis Sweet is a species of Andean legume with a high content of proteins, which present hemagglutinating lectins. Here, we demonstrated that the γ-conglutin lectin isolated from L. mutabilis seeds is responsible for the hemagglutinating activity by evaluating this activity at each step of the isolation process. Methods: Seeds of three ecotypes of L. mutabilis were used. Saline protein extraction size exclusion and ionic exchange chromatography were performed to isolate the lectin. Carbohydrate specificity, thermostability and resistance to chelating and reducing agents of the lectin were tested. SDS-page and mass spectrometry were performed to characterize the isolated hemagglutinating lectin. Rabbit erythrocyte hemagglutination test was performed at each step. Result: Patón Grande ecotype had higher hemagglutinating titers and therefore was selected for further purification steps. Hemagglutinating activity of the purified lectin, which was identified as a γ-conglutin, was cation-independent and optimal between 15-20°C. Besides, it resisted temperatures up to 70°C, its activity was lost in basic pH and remained active under reducing and chelating conditions.