Study On The Properties Of Water Dispersion System Of Soybean 7S And 11S Globulin In Different Ratios

Because of different structures and properties of 7S globulin and 11S globulin,they have different effects on the structure and functional properties of the soybean protein water dispersion system.In order to investigate the effects of different content of soybean 7S globulin and 11S globulin in soy protein water dispersion system,the soybean protein system with 7S globulin and 11S globulin compounded in different proportions was studied.In order to explore the mechanism of the interaction between the 7S globulin and 11S globulin on the properties of soy protein water dispersion system,the structure and function of the dispersion were analyzed,to provide a theoretical basis for the subsequent processing and improvement of soybean protein products.At the same time,in order to further study the theoretical system of the structure-activity relationship of soybean protein from the molecular level in the further study,the?subunit of soybean 7S globulin was initially isolated,which provided experimental materials for subsequent research.The main conclusions of this research are as follows:7S and 11S globulin were isolated from Lu 96150 soybean seeds by isoelectric point precipitation method,and the purified target protein was obtained by gel filtration on agarose gel CL-6B.According to the optimized selection of the conditions for purification of proteins by gel filtration chromatography in previous studies,the following chromatographic conditions were selected:the column size was 1.6×50 cm;the chromatography column was agarose gel CL-6B;The loading quantity of protein sample was 500 mg;the elution rate was0.3ml/min,and 5ml of the eluate was collected per tube.After SDS-PAGE gel electrophoresis,the purity of 7S globulin was 89.9%and the purity of 11S globulin was 40.1%after analysis by Image J software.The subunit of soybean 7S globulin was isolated and purified by DEAE agarose gel FF ion exchange chromatography column.Combined with the results of previous studies,the chromatographic conditions selected for this experiment were:protein loading quantity of500 mg;natural soybean 7S globulin was incubated in 8 mol/L urea,pH=8.0 phosphate buffer for 4 hours.A linear gradient elution was carried out with a phosphate buffer containing 0 to 0.4 mol/L NaCl at an elution rate of 0.3 ml/min.Two distinct separation peaks appeared in the elution curve.Combined with the molecular weight analysis of the electropherogram,the purity of the?subunit was 85.77%by Image J software.Differential scanning calorimetry analysis of the thermal properties of proteins showed that the thermal deformation range of 7S and 11S globulin components was significantly different.The denaturation temperature(T_d)of 7S globulin was 70.94°C,and the denaturation temperature of 11S globulin(T_d)was 84.59°C.The observed thermal deformation transition peak indicates that the 7S and 11S globulin samples are in an incompletely denatured state.The results of Fourier transform infrared spectroscopy indicated that the different proportions of soybean 7S/11S globulin had the same form of spectrum,and the content of?-sheet decreased gradually with the increase of 11S globulin content,whereas the content of?-helix,?-turn and random curls gradually increased.The surface hydrophobicity of the compound system was positively correlated with?-sheet content,and negatively correlated with the content of?-helix.The solubility of different proportions of soybean 7S/11S globulin aqueous dispersion was negatively correlated with the exposed sulfhydryl content,total sulfhydryl content and surface hydrophobicity.With the increase of 11S globulin content in the system,the solubility of the soybean protein water dispersion system increased gradually,while the exposed sulfhydryl content,total sulfhydryl content and surface hydrophobicity index decreased gradually.The particle size and absolute value of zeta-potential of 11S globulin is significantly greater than that of 7S globulin.With the increase of 11S globulin content in the composite dispersion system,the particle size and absolute value of zeta-potential increased gradually,and the PDI value gradually decreased,indicating that the dispersion of globulin in aqueous solution gradually became uniform.