Food-derived Bioactive Peptides And Their Interaction With Cellular Membrane Models

The bioactivities of food-derived proteins is mainly attributed to the peptide fragments released from gastrointestinal digestion.In this study,in vitro enzymatic hydrolysis method was used to prepare zein hydrolysates?ZH?and soybean?-conglycinin hydrolysates?7S-Pep?The potentials of ZH as delivery systems for hydrophobic bioactive molecules were then systematically evaluated and investigated.The interactions between peptides?ZH and 7S-Pep?and cellular membrane models were also studied.These findings would help to understand the possible cholesterol-lowering mechanism of 7S on molecular level and provide the theoretical and technical supports for the development of bioactive peptides delivery systems in the food industry.The main conclusions are as follows:?1?The?-zein hydrolysate??-ZH?was used as a new delivery system for hydrophobic bioactive molecules such as curcumin?Cur?.?-ZH-Cur nano-complexes were successfully formed via the hydrogen bonding and hydrophobic interactions.Compared to?-ZH,the complexation of Cur in?-ZH showed a better improvement in the water solubility and physicochemical stability of Cur,and showed greater potential for absorption of Cur.These differences between?-ZH and?-ZH may be associated with the differences in the amino acid composition,such as more cysteine in?-ZH.?2?The interactions between the N-terminal proline-rich sequence of?-ZH,?VHLPPP?_n=1?₃and cellular membrane models?liposomes and Langmuir-Blodgett monolayers?were further studied.?VHLPPP?_n=1?₃ could bind to DPPC cellular membrane models.This binding behavior induced peptides to form PPII structure,increased the surface pressure and fluidity of lipid monolayer,decreased the stability of lipid monolayer,and induced the formation of liquid-expanded phase?LE?of lipid monolayer.?VHLPPP?₃ showed the stronger binding affinity with cellular membrane models compared to the?VHLPPP?₁.?3?The interaction between 7S-Pep and cellular membrane models?liposomes and Langmuir-Blodgett monolayers?was also studied to obtain an underlying molecular mechanism on the cholesterol-lowering effect.7S-Pep were bound to DPPC/DOPC/CHOL liposomes mainly through hydrogen bonds and Van der Waals'force,and the presence of cholesterol enhanced the binding affinity.The incorporation of 7S-Pep increased the lipid monolayer fluidity and the size of lipid rafts.The presence of cholesterol accelerated the7S-Pep accumulation on the lipid rafts,which could serve as platforms for peptides to develop into?-sheets rich structures.