The Studies On Protein Digestomics Of Milk And Deer Velvet Antler

Food Proteomics is an analytical strategy of investigating the changes and beneficial effects on human health of peptides surviving in gastrointestinal digestion based on mass-spectrometric techniques and has been a global active research field.Liquid Chromatograph-tandem Mass Spectrometry(LC-MS/MS)was used to establish a protein digestomis model to analyse food proteins during simulated gastrointestinal digestion in this paper.The model was used to investigate the peptide profile and bioactivities of yogurt,milk and antler velvet aqueous extract and the structure-activity relationship is also discussed to screen potential bioactive peptides.The main parts of this paper were divided in three sections:1.Protein digestiomics of yogurt.Food protein digestomics model was used to study the peptide profile and bioactivities of yogurt and digests after simulated gastrointestinal digestion.A total of 250,434 and 466 casein peptides were identified by LC-MS/MS in yogurt,gastric and pancreatic digests,respectively.Forty common peptides were identified in three samples.Angiotensin converting enzyme(ACE)and dipeptidyl peptidase IV(DPP-IV)inhibitory activity were used to evaluate the biological activities of peptides in yogurt and digests.The ACE inhibition rates of yogurt,gastric digests and pancreatic digests were 14.15 %,23.78 % and 52.71 % at the concentration of 0.1 mg/mL,respectively.The DPP-IV inhibition rates of yogurt,gastric digests and pancreatic digests were 8.94 %,21.19 % and 63.34 % at the concentration of 2.5 mg/mL,respectively.Three novel peptides,FVAPFPEVF,PPFLQPEVM and QEPVLGPVRGPFPIIV were screened out and PPFLQPEVM had optimal ACE and DPP-IV inhibitory activities.The half maximal inhibitory concentrations(IC50)were 0.037 and 0.464 mg/mL,respectively.The results showed that when yogurt was sequentially hydrolyzed in the gastrointestinal trials,the increase of peptides helped to improve the bioactivities of yogurt.2.Protein digestiomics of milk caseins.Food protein digestomics model was used to analyse the changes of Caseinophosphopeptides(CPPs)in milk and digests after simulated gastrointestinal digestion.Ti4+-IMAC was used to enrich CPPs in milk and digests.A total of 65,73 and 124 CPPs were identified by LC-MS/MS in milk,gastric and pancreatic digests,respectively.Most of identified CPPs were mono-phosphorylated.Four common peptides,VPQLEIVPNSpAEER,FQSpEEQQQTEDELQDK,IEKFQSpEEQQQTEDELQDK and RELE-ELNVPGEIVESpL were identified in three samples.Milk peptide profile indicated that endogenous CPPs in milk were primarily generated by plasmin,a main kind of endogenous proteinase.In total,25 CPPs with structure “SpSpSpEE” and 32 phosphopeptides with threonine(The)residues,were identified in milk and digests,which increasing the diversity of CPPs.Meanwhile,our research found that CPPs with structure “SpSpSpEE” couldn't resist digestion.3.Protein digestiomics of antler velvet aqueous extract.Food protein digestomics model was used to analyse the peptide profile of antler velvet aqueous extract(AAE)and digests after simulated gastrointestinal digestion.DPP-IV inhibitory activity and Prolyl Endopeptidase(PEP)inhibitory activity were used to evaluate the biological activities of peptides in AAE and digests.In total,23,387 and 417 peptides were indentified in AAE,gastric digest of AAE(GDAAE)and pancreatic digest of AAE(PDAAE).The DPP-IV inhibition rates of AAE,GDAAE and PDAAE were 3.47 %,16.27 % and 42.35 % at the concentration of 2.5 mg/mL and the PEP inhibition rates of GDAAE and PDAAE were 23.14 % and 26.52 %,respectively.AAE did not present PEP inhibitory activity.The DPP-IV IC50 of four novel peptides from AAE and digests,LPQPPQE,GPAGPQGPR,LPPLTAD and PPGLPGSPGQ,were 0.78,0.43,1.22 and 0.50 mg/mL,respectively.The PEP IC50 of LPQPPQE,LPPLTAD and PPGLPGSPGQ were 2.13,0.52 and 0.71 mg/mL,respectively.GPAGPQGPR did not present PEP inhibitory activity.These results indicated that the main component of AAE was protein and it released a large number of peptides with DPP-IV inhibitory activity and PEP inhibitory activity after simulated gastrointestinal digestion.