Extraction, Isolation And Purification Of Lectin From Leguminosae Beans

Lectins are essential and ubiquitous in plants. Over70different lectins have been identified in various legumes till now. They are carbohydrate-binding glycoproteins which can specifically recognize and reversibly bind to carbohydrates. They also display a variety of biological activities including anti-tumor, immunomodulatory, anti-fungal, anti-human immunodeficiency virus (HIV), and anti-insect. In the present study, small black kidney beans (P. vulgaris) was chosen as an example and its lectin extraction conditions were determined. Lectins from23types of beans from Northeast China were measured in contents and vitality.4types of representative legume lectins were purified. Furthermore, the distribution of lectins in different parts of legume beans was studied.Firstly, extractant, solid-liquid ratio, pH and extracting time were determined for crude extraction of legume lectins. Results showed that (1)different extractants had significant effects on the yield of lectins;(2)the optimum solid-liquid ratio was1:10;(3)pH also had an effect on the extraction of lectins;(4)the special vitality of lectins rise gradually over time. Ammonium sulfate fractional precipitation was performed afterwards. Chromatography of little black kidney bean extract on DEAE-52and Superdex-200were performed for further purification. SDS-PAGE analysis showed that a single protein fraction was obtained after the purification process. In addition, lectins from22other kinds of legume were extracted and isolated using the same method for black kidney bean.Lectins are widespread in many leguminous plants. However, their studies are subjected to soybean, mung bean, cowpea and several other limited species. Recent researches have changed their subjects to Phaseolus beans while only preliminary isolations are involved. It is reasonable to predict that deeper investigations into lectins from various leguminous species will be a potential research hot-spot.