Preparation Of Tibetan Egg Ovalbumin Active Polypeptide And Its Effect On Lipid Metabolism And Intestinal Flora In Rats

The proteomics characteristics in Tibetan chicken egg ovalbumin,compared to ordinary eggs,using isobaric tags for the relative and absolute quantification labeling technique(iTRAQ).The results showed that 165 proteins were identified and 56 proteins were significantly changed including 34 significantly upregulated and 22 significantly downregulated proteins.The more abundant proteins of the Tibetan ovalbumin included vitellogenin-2,vitellogenin-1,vitellogenin,apolipoprotein A-1,and serum albumin,which were upregulated.GO(Gene ontology)analysis showed that these proteins were involved in the biological processes of cells.KEGG(Kyoto Encyclopedia of Genes and Genomes)pathway analysis results showed the four enrichment pathways with significant influence.Protein-protein interaction(PPI)analysis showed that vitellogen-2,vitellogen-1,vitellogenin,apolipoprotein A-I and serum albumin had strong interactions and were associated with PPAR lipid metabolism pathway.The enzymatic hydrolysis technology of alkaline protease,pepsin and papain was studied,the optimum conditions of enzymatic hydrolysis were optimized,and the optimum preparation technology of TEOP was obtained.The TEOP's DPPH,O2-· and hydroxyl radical scavenging capacity and the analysis of lipid oxidation resistance were measured.The results showed that the pepsin is the best protease for TEOP preparation by TEO.The optimal enzymatic hydrolysis conditions were as follows:8000U/g,3%substrate mass,4h enzymatic hydrolysis time and the O2·-scavenging rate of enzymatic lysates was 80.66%,DPPH radical scavenging rate was 69.90%,hydroxyl radical scavenging rate was 85.09%,and lipid oxidation resistance was 54.51%.Column chromatography gradient elution method was used to isolate enzym atic TEOP according to the antioxidant activity of polypeptides collected seperatly.The results showed that active peptides 1(SP1)had the strongest antioxidant activity,mainly short chain peptides with molecular weight within 100kDa and length of 6-10 amino acids.Invivo tests showed that TEOP could reduce the body weight,liver weight and liver index of high-fat rats,inhibit the formation of fatty liver,and reduce the blood alanine transaminase,glutinous straw transaminase and creatinine of high-fat rats,thus playing a protective role in liver.TEOP can reduce the levels of TG,TC and LDL in the high-fat group and increase the level of HDL,which has the function of lowering lipids.It can increase the activity of SOD,CAT and gsh-px enzymes in rat liver,reduce the content of MDA in liver,and improve the antioxidant capacity of the rats.Through analyzing the expression of genes related to lipid metabolism,it was found that the lipid-lowering effect of TEOP may be realized by down-regulating mRNA and protein expression of SREBP-2 and HMG-CoA in liver,and up-regulating mRNA and protein expression of PPAR-? and LDLR,which may be one of the molecular mechanisms of TEOP lipid-lowering effect.The cluster analysis of intestinal flora OTU abundance samples showed that TEOP could reduce the OTU species differences caused by high-fat diet.The OTU abundance of the high-fat group significantly deviated from the normal group,while TEOP could make the OTU abundance closer to the normal group,with the most significant effect in the medium dose group.Phyla level analysis showed that TEOP could effectively increase the abundance of beneficial bacteria such as Verruciformis and Bacteroidetes in the intestinal tract,and reduce the abundance of hararmful bacteria such as Firmicutes and Proteobacteria.The abundance of Akkermansia in the medium dose group was even higher than that in the normal group.Genus level analysis showed that the abundance of Blautia,Barnesiella and Clostridium IV was decreased.UniFrac analysis showed that the high-fat group deviated far from the normal group,while the TEOP middle dose was the closest to the normal group.COG and KEGG function analysis showed that TEOP can significantly improve expressiong of related mRNA in lipid metabolism and lipid transfer function,the most significant effect was observed in medium dose group.This may be another way that TEOP play a role in lipid-lowering.TEOP may adjust the intestinal flora and improve the levels of lipid metabolism and lipid transport.