| Soybean protein is the quality resources of food protein, and plays an important role in protein supply in the daily diet for people in China. Soybean protein and its derivatives could regulate intestinal function. Soybean glycoprotein (β-conglycinin) was hydrolyzed using alcalase2.4L and soybean glycopeptides (SGP) was seperated from β-conglycinin hydrolysate in previous study. SGP could inhibit the adhesion of pathogens on human intestinal cells, but the mechanism of this effect and role of carbohydrate chain are still unclear. Based on these results, interactions between SGP and host cells and the role of carbohydrate chain in inhibiting adhesion were examined in this study. The mechanism of inhibiting adhesion was also analyzed in this study. The study provides theoretical foundation for regulation of SGP biological activity and application of the technical innovation. On the basis of theoretical research, the in vitro digestibility and thermal stability of β-conglycinin hydrolysates were also evaluated in this study, which could supply the technical foundation for the application of β-conglycinin hydrolysates as functional component for intestinal health in food industry.The carbohydrate chain in SGP was destroyed partly by periodate treatment and properties of periodate-treated SGP were also examined in this study. Results showed that the carbohydrate content in SGP decreased from15.44%to10.93%after periodate treatment. The electronegativity, content of peptides with relatively low molecular weight and the content of component with relatively high hydrophobicity were increased in periodate-treated SGP. Moreover, the exposure of the aromatic amino acids in periodate-treated SGP changed. These results indicated that periodate treatment could destroy part of sugar chain and led to conformation changes in SGP.The changes in Zeta potential and cell membrane fluidity of Caco-2cells with or without SGP and the binding interaction between SGP and cell membrane were examined using a Caco-2cell model. Results showed that the cell surface Zeta potential decreased after30min of incubation with SGP and then slowly restored to the level of Caco-2cells alone within24h. Fluorescent experimental results showed that SGP could bind to the cell membrane, and increase the membrane fluidity of Caco-2cells. The extent of binding decreased when the lipid rafts in the cell membrane were destroyed, indicating that SGP bound to the cell membrane on lipid rafts,The inhibitory effects of SGP and periodate-treated the SGP on the pathogenic bacteria adhesion intestinal cells were compared. Results showed that SGP presented inhibition effect on the bacterial adhesion to the host cell. The inhibition effect of periodate-treated the SGP on Escherichia coli adhesion were significantly lower than SGP, but there was no significant differenece between the inhibition effects of SGP and periodate-treated the SGP on Salmonella adhesion. Moreover, the increasing extent of membrane fluidity of Caco-2cells affected by periodate-treated the SGP was lower than SGP. These results suggested that carbohydrate chain in SGP played an important role in inhibiting Escherichia coli adhesion to intestinal cells.The stability of P-conglycinin hydrolysates was foundation of using it in food processing. The stability of soybean β-conglycinin hydrolysates in heat treatment (85℃,30min) was studied. Results indicated that heat treatment caused β-conglycinin hydrolysates soluble aggregation and the aggregation degree related to sample concentration. β-Conglycinin hydrolysates solution had good heat resistance at lower concentration (<200mg/mL), while heat treatment induced electronegativity increased and calcium sensitivity decreased at higher concentration. The digestibility in vitro of P-conglycinin hydrolysates was also studied. The results showed that β-conglycinin hydrolysates were degraded through in vitro digestion, but the degree of degradation was relatively low. The content of peptides with molecular weights from10kDa to20kDa remained stable during digestion in vitro. The proportion of highly hydrophobic peptides decreased through in vitro digestion, but no significant change in the surface hydrophobicity indices of digestion products was observed (P<0.05). These results indicate that peptides with molecular weights from10kDa to20kDa in the β-conglycinin hydrolysates resisted digestion by pepsin and trypsin and they remained stable during in vitro digestion. |
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