The Stability and in Vitro Digestibility of Lectin from Tartary Buckwheat(Fagopyrum tataricum)

Purpose:To purify lectin from tartary buckwheat(TBL)seeds and investigate the stability and digestibility of TBL in vitro. Methods:Acid buffer was used to extract TBL from the defatted buckwheat flour and anion exchange chromatography was applied to purify TBL. The effects of heat treatment,pH,the digestibility of TBL in simulated gastric fluid(SGF)and simulated intestinal fluid(SIF)were studied,using kinetic densitometric analysis for SDS-PAGE. Results:Extraction with acid buffer simplified the purification protocol,as TBL was separated to electrophoretic purity by only one step of chromatography. After heated in boil water for 60 min,more than half of TBL still remained. Furthermore,no obvious degradation was observed after TBL was placed in different buffers ranging from pH4 to 12 for 30 min. It was found that TBL was reasonably stable in SGF with a half-time of digestion of 10 min. In SIF it was extremely stable. Even after 50 min of digestion there was no discernible degradation. But the susceptibility of TBL to hydrolysis by proteases was markedly increased by preheating. The preheated protein was totally degraded in both SGF and SIF after being digested for only 10 min and the protein band disappeared by SDS-PAGE. Conclusion:TBL was stable when exposed to heat and over a wide pH range. Moreover,no trypsin digestion was observed and hydrolysis upon exposure to pepsin was limited. However,preheating could obviously increase the digestibility of BTI in SGF and SIF.