In vitro studies of the digestibility of lectin from black turtle bean (Phaseolus vulgaris)

In this study, the in vitro digestibility of lectin from black turtle bean was investigated in simulated gastric fluid (SGF) and tryptic digestion, using kinetic densitometric analysis for SDS–PAGE and spectroscopic measurements. It was found that the native lectin was relatively stable in both SGF (half-life = 22.71 min) and tryptic digestion (half-life ⩾90 min), the susceptibility of the protein to hydrolysis by proteases was markedly increased by preheating and also enhanced by demetallization. An unfolding state of the preheated lectin was observed by UV and fluorescence spectroscopy, although the conformational changes were found to be limited by the demetallization. This study provides evidence that metal ions may provide resistance during protease hydrolysis, and suggests both preheating and demetallization contribute to in vitro proteolytic degradation of lectin.