Research On The Renaturation Law Of Soybean 11S Globulin Based On Three Denaturation Treatments

Soy protein is widely used in meat processing,functional foods and environmentally friendly materials.These products will experience changes in pH,temperature and denaturant during processing.This series of processing operations may cause changes in the structure of soy protein,And even sex change.Under certain circumstances,some of the processing characteristics of soy protein can be improved by controlling the performance of soy protein,but denatured protein often leads to a decrease in its solubility in water,emulsifying properties and foaming properties will also be affected,limiting soy protein Exertion of excellent processing characteristics.If these denaturing factors are changed or removed,whether these denatured proteins can undergo renaturation and the functional changes before and after renaturation need to be systematically studied.A deeper understanding of the renaturation law of denatured proteins is the key to exploring protein stability,and it has certain guiding significance for the development of proteins with good functionality.In this study,soybean 11S globulin(11S)was the main research object,and 11S obtained by gentle extraction in the laboratory was regarded as the natural state(N).The pH of the acid-base denatured 11S was adjusted to neutral to induce renaturation.The denatured 11S was naturally renatured for 10 weeks,and the guanidine hydrochloride(GuHCl)denatured 11S was subjected to dilution and renaturation studies,and then explored whether they can renature and their secondary structure and tertiary structure during the renaturation process.The structure,surface hydrophobicity and particle size change,and the effects of solubility,foaming performance and emulsification characteristics before and after 11S renaturation were investigated.The main findings are as follows:(1)In the process of adjusting the pH of 11S denatured by acid(pH 3.0)and alkali(pH 10.0)to neutral and induce renaturation,fluorescence and ultraviolet results show that the stretched tertiary structure has undergone different degrees of refolding and Present dynamic changes.The circular dichroism showed that the negative peaks at 210 nm and 222 nm were slowly red-shifted during the 11S renaturation process under the two denaturing conditions,indicating that the stretched protein molecules were continuously shrinking.ANS fluorescence shows that the surface hydrophobicity of acidic ANS is lower than that of alkaline,and the ANS hydrophobicity of 11S is negatively correlated with a-helix content.During the renaturation process of alkalidenatured 11S,the particle size,solubility,foamability,and emulsification are continuously reduced,but are better than the natural state;while acid-denatured 11S,these properties first decrease and then increase during the renaturation process.trend.(2)After heat-denatured 11S at 100℃/15 min and 100℃/30 min,the tertiary structure and secondary structure of heat-denatured 11S cannot be renatured within 0～10 weeks.With the prolongation of the cycle,the molecular structure of thermally denatured protein becomes more stretched,and the particle size gradually increases,but its solubility,foaming,emulsifying and emulsifying stability properties all show a downward trend.(3)During the dilution and renaturation process of 11S denatured by 8.0 mol/LGuHCl,the fluorescence spectrum combined with circular dichroism spectrum showed that with the decrease of GuHCl concentration,the α-helix,β-folding and β-turning angle content of denatured 11S gradually recovered,and the structure became more orderly,and the opened secondary and tertiary structure gradually recovered,and the renaturation degree was the highest when the concentration of GuHCl was diluted to 0.4 mol/L.Compared with the natural state,the renaturation of 11S was the highest when the concentration of GuHCl was diluted to 0.4 mol/L.There are still some secondary structures missing.In the process of dilution and renaturation,the"molten globule state" was formed when the concentration of GuHCl was diluted to 2.0 mol/L.Compared with the natural state,the foaming ability and foaming stability were increased by 5 times and 2.2 times,respectively,and the emulsifying property and emulsifying stability were increased by 1.5 times and 2 times,respectively.