Structure And Lipidomics Analysis Of Hen Egg LDL And Its Effect On Mice Blood Lipid Metabolism

Low density lipoprotein is spherical particle.TAG and cholesterol make the core,which was surrounded by a layer of single phospholipid membrane with protein embedded.LDL is the main component of hen egg yolk,accounts for about 2/3 parts of yolk dry weight,and has important processing character and nutritive value.This project developed research about extraction optimization of LDL,structure analysis,fatty acid analysis,lipidomic analysis and effect on blood lipid metabolism.The main research results are as following:We constructed a high efficiency and low oxidative degree separation method of hen egg yolk LDL with PEG.An optimized experimental condition of 5% PEG 4 000 and p H 6.00 with 0.02% Vc addition was obtained,with an oil concentration of 68.14 g/100 g DM and protein concentration of 68.91%,of which the oil concentration was significant higher than and the oxidation degree was significant lower than that of ammonium sulfate precipitation method(p<0.05).The PEG precipitation method can extract low oxidative degree hen egg yolk LDL with high efficiency.We analyzed the particle size and distribution of two LDL samples extracted by two separation methods.The results showed that two LDL samples have similar particle size(15-40 nm),shape and distribution.However,LDL extracted by ASP method proved to be more aggregation than PEG-LDL with same concentration.Structure analysis showed that the two LDL samples have similar surface secondary structure and some difference from the plasma sample.The main difference between LDL and plasma is the secondary structure of amide?band.FTIR and Raman spectrum demonstrated that the LDL sample have symmetry and asymmetry stretching vibration of CH2,C=O vibration of apoprotein peptide,P=O stretching vibration of lipid chain,asymmetry vibration of choline and stretching vibration of C=C.The results showed that LDL extracted by two methods have similar structural characteristics,while the PEG-LDL has higher dissolving capacity.We employed HPLC/MS/MS to detect lipid species of yolk and LDL under both positive and negative ion mode.A total of 387 lipids were detected,which belong to 24 lipid species.In LDL lipid sample,the PL contents was lower than yolk sample,while the TG and CE contents were higher than yolk sample,which indicate that TG and CE of yolk were riched in LDL particle.To analyze the fatty acids composition of different lipid species,we found that the main fatty acids in yolk and LDL oil samples were C16:0,C18:0,C18:1 and C18:2.Two methods were employed to extract lipids in LDL,and the results showed that the two lipid extraction methods complement with each other.Fatty acids contents of ASP-LDL and PEG-LDL showed significant difference with each other.PEG-LDL had less SFA and more MUFA,which was highly nutritive.To analyze the fatty acids composition of TL,NL and PL of LDL lipid samples,the main fatty acids of TL were C16:0,C18:0,C18:1 and C18:2,the main fatty acids of NL were C16:0 and C18:1,and the main fatty acids of PL were C16:0,C18:0,C18:1 and C18:2,which verified the previous lipidomic results.We developed research about growing development,physiology and chemistry index of mice with LDL gavage under both Chow Diet and High Fat Diet modes.The results showed that LDL gavage can significant improve the weight growth rate of mice.HFD-LDL can significant increase the body fat rate of mice.Anatomy of the abdominal cavity and HE tissue slice of hepatic and Epi fat of 100 d-HFD-LDL group showed a tendency of hepatic lesion.OGTT and ITT results all proved that no mice have diabetes.The results demonstrated that HFD seems to be easier to cause a reduction of OGT and produce insulin resistance.The results of serum biochemistry showed that Chow Diet can give rise to serum TAG content more easily than the High Fat Diet.Our research results showed that a short time LDL gavage under Chow Diet can improve the fatty acid component and promote the outflow of hepatic lipids,while a long time LDL gavage can cause lipid accumulation in hepatic.CD-LDL can significant increase LDL-C level,while HFD-LDL can significant decrease serum LDL-C level.We researched the effect of LDL on mice blood lipid metabolism.The results showed that LDL can significant reduce Fasn expression level,and slow down the lipogenesis speed in hepatic.A long term of LDL gavage under both diet modes can significant reduce MTP expression level,cause the accumulation of fatty acids in hepatic,lead to hepatic lesions,and significant reduce fatty acid content in fecal.LDL can improve the fatty acids constituent of mice serum and 100 d hepatic by increasing the content of n-3 PUFA.We also made lipidomic analysis of serum and hepatic lipids.