Effects Of Fat On The Progress And Structural Changes Of Ovalbumin Glycosylation

Glycosylation and lipid peroxidation are commol/Lon reactions during food processing and storage.They impart unique color,flavor,texture and texture to foods,and also produce substances that are harmful to the human body,such as advanced glycation end products(AGEs)and advanced lipid peroxidation end products(ALEs).The two reactions are highly correlated,promoting and competing with each other within the food system.In this experiment,ovalbumin was used as the amino source,glucose was used as the carbonyl source,and a glycosylation model system containing different saturated fatty acids(EPA,LIN,OLE)and a simulated glycosylation system containing different saturation edible oils(soybean oil,butter,palm oil)were established.They are used to compare with lipid-free glycosylation systems.To investigate the effect of lipid peroxidation on dicarbonyl compounds in glycosylation systems by measuring the changes in 3-deoxyglucosone(3-DG)and glyoxal(GO),and To investigate the effects of lipid peroxidation on advanced glycation end products(AGEs)in the system by measuring the changes in pyrraline(PRL)and carboxymethyl lysine(CML).Combined with the above indicators,explore the effect of lipid peroxidation on the glycosylation process of proteins by measuring representative lipid peroxidation indicators(POV value,TBA value).The effect of the addition of lipids on the structure of glycosylated proteins was investigated by measuring ultraviole absorption spectra,fluorescence spectra and 3-D fluorescence spectra,circular dichroism spectroscopy,and gel electrophoresis.The main findings are as follows:(1)The higher the unsaturation of fatty acids or edible oils,the higher the content of 3-DG and GO in the system.The addition of EPA significantly promoted the formation of 3-DG and GO in the system(p<0.05),while the addition of OLE and LIN was not conducive to the accumulation of 3-DG and GO in the system.The content of PRL and CML in the lipid-containing system is higher than that in the GLC+OVA system(p<0.05).It shows that lipids can promote the formation of P RL and CML in the system.The higher the lipid unsaturation,the weaker the promotion of PRL and CML.The TBA value in the pseudo-system is significantly higher than that in the GLC+OVA system(p<0.01).It shows that most of the MDA in the system comes from lipid peroxidation.The higher the lipid unsaturation,the greater the MDA content produced.The POV value in the simulation system showed a downward trend.The rate of decline gradually slows as the reaction time increases.The higher the lipid unsaturation,the faster the rate of decline(p < 0.05).It shows that the higher the lipid unsaturation,the stronger the effect on each reaction step in the system.(2)Regression analysis of the data,path analysis of the SEM structural model shows that lipid oxidation has a significant impact on the glycosylation process.Lipid peroxidation secondary products have a strong influence on glycosylation intermediates(path coefficient 0.814),and the effect on glycosylation end products is relatively weak(0.246).The lipid peroxidation primary product has a stronger influence on the final glycation end product(0.412),and has a weaker influence on the intermediate product(0.331).(3)Analysis of the structure of OVA in different systems shows that the addition of lipids causes an increase in the intensity of the OVA ultraviolet absorption peak.The higher the lipid unsaturation,the greater the intensity of the absorption peak.Lipids promote the progression of the Maillard reaction in the system,producing more products with UV-absorbing properties.Lipids reduce the endogenous fluorescence intensity of OVA.The higher the lipid unsaturation,the weaker the endogenous fluorescence intensity of OVA.Lipid peroxidation promotes the progress of the OVA glycosylation reaction and promotes the consumption of fluorescent amino acid residues.It can be seen from the circular dichroism spectrum that the change of the OVA single-component secondary structure is larger than that of the simulated group and the control group.It shows that the Maillard reaction can alleviate the secondary structure changes of OVA.The secondary structure change increases with the increase of oil unsaturation,which indicates that the oil promotes the Maillard reaction.Protein gel electrophoresis showed that lipid addition can alleviate the upward shift of the protein band.The higher the lipid unsaturation,the more obvious the relief.It shows that lipid peroxidation alleviates cross-linking polymerization between OVA molecules.