Extraction, purification by cation exchange supermacroporous cryogel and physico-chemical characterization of γ-conglutin from lupin seeds (Lupinus albus L.)

This study focused on the extraction, purification, and physicochemical characterization of gamma-conglutin, a protein present in lupin seeds with properties of reducing blood glucose levels. Total protein was extracted with an alkaline-saline solvent, followed by isoelectric precipitation. Chromatographic purification of the precipitated fraction was performed using a cation exchange supermacroporous cryogel column. Electrophoresis of the eluted fraction from chromatography presented a single band of similar to 48 kDa under non-reducing conditions (two bands of similar to 30 and similar to 17 kDa, under reducing conditions) confirming the success of the purification protocol. Liquid chromatography-tandem mass spectrometry analysis confirmed the identity of the protein as gamma-conglutin. The purified gamma-conglutin had an isoelectric point of 7.51, beta-sheets prevailing as a secondary structure, and denaturation temperature close to 68 degrees C. The outcome of this work showed that gamma-conglutin was obtained with a high degree of purity. The proposed purification protocol is simple and can be easily scaled up.