Research On The Glycosylation And Thermal Aggregation Of Soybean Globulin-polysaccharide

The conjugations of protein and polysaccharide based on Maillard reaction mechanism are the protein modified method with green and effective, but because of its glycosylation methods are some limitations, it is difficult to achieve controllability and industrial applications, how current glycosylation analysis and comparison of methods to better improve, become the focus of attention, and after the protein through glycosylation, to study the thermal aggregation of proteins and thus the nature of the effects attained through control of protein glycosylation thermal aggregation behavior also improve the thermal properties of soy protein an important subject area. This systematic study of soybean 7S globulin and dextran of different glycosylation methods different response mechanisms, and different sugar chain length on the nature of glycation products and structure implications of glycosylation for the soybean 7S, respectively globulin its thermal aggregation, gel and soy 11S globulin thermal aggregation properties.Hydrothermal method can inhibit the advanced stage of the Maillard reaction of the proceedings, and there is a corresponding increase for fuctional properties of products of the Maillard reaction, so it is shown that pressure can control of glycosylation reactions to the ideal stage.Preparation of three glycosylation reaction method's extent of reaction height order is in turn: the liquid heat method > hydrothermal method > the dry heat method, dry heat method crowded reaction, mild reaction conditions, mainly formed in the Maillard reaction products of the early and mid-late early the ideal response phase, and response to severe heat method, the protein peptide chains prone to aggregation and started to speed up the Maillard reaction, formed in the Maillard reaction product of more advanced stage. Solid-phase system of water than the system for greater impact protein structure, secondary structure on one hand, found that wet heat and the product of hydrothermal preparation ofα-helix content decreased, the other on the tertiary structure shows that dry thermal method for the tertiary structure of the change was not obvious, but heat and hydrothermal method for the tertiary structure of protein molecules have a significant impact, in the internal hydrophobic domain of tyrosine molecules as the protein peptide chain gradually expand the exposure peptide surface. Soybean 7S globulin after the glycosylation the thermotropy temperature had the enhancement, three kind of glycosylation product G67, G150 and G500 denatured peak value temperature Tp respectively was 84.81±0.47°C, 87.34±0.31°C and 86.32±0.27°C, thermotropy enthalpy value H respectively be 5.271±0.48, 7.612±0.25 and 7.795±0.19 J/g. Soybean 7S globulin in the thermal aggregation of macro-aggregates, the glycosylation of soybean 7S globulin inhibited the pH value and ionic strength for the thermal aggregation induced by the formation of macroscopic aggregates. Soybean 7S globulin glycosylation products in the heating process, the glycosylation reaction of depolymerization of macromolecules into soluble polymer will be a better thermal stability of polymer molecules so as to enhance the soybean 7S globulin solution of the thermal stability, G67 and G150 significant differences in inhibition, G500 inhibitory effect was slightly lower than the other two.By covalently binding dextran into the protein peptide chain, to a certain extent changed the spatial structure of proteins. In the secondary structure, the introduction of sugar chain does not change the main structure of soybean 7S globulin (β-structure), the main increase in protein secondary structure random coil structure; tertiary structure, with the sugar chain extension, the introduction of greater steric hindrance to block out a greater extent with the signal near ultraviolet region of the original two signals aromatic amino acid, particularly phenylalanine characteristics of the signal decreased.Glucan to access non-covalent protein peptide chain and covalently access the sugar chain steric played the role of soybean 7S globulin given thermotropic gel system of different functions, non-glucan were access to the protein peptide bond, its steric effect is conducive to the improvement of the nature of heat induced gels to covalently binding dextran steric effect is conducive to the protection of thermal denaturation and the formation of protein gels. Covalently binding dextran and protein molecules can be uniformly distributed in the gel network structure, and will not cause phase separation, non-covalent mixture of uneven distribution of dextran molecules in the protein gel network structure, with the mixed dextran molecular weight increases, the induced phase separation more clearly.Glycosylation increased soybean 7S globulin of soybean 11S globulin for the inhibition of thermal aggregation of the three inhibitory effect of glycation products difference is not strong, glycosylation of soybean 7S globulin inhibited the soybean 11S globulin role in the dextran molecular weight of 67-500 kDa, it neglected the differences in access to sugar chain length. Glycosylation of soybean 7S globulin in the heating process before the formation of a smaller molecular weight relative heating and better thermal stability, but glycosylation product of soybean 11S globulin dispersions heated, this part of the glycosylation products and soybean 11S globulin basic subunit generate better thermal stability of a class of compounds. In more extreme conditions (pH value or ionic strength) of soybean 7S globulin glycosylated glycosylation than not soybean 7S globulin inhibited the thermal aggregation of soybean 11S globulin better, and different mechanisms, mainly due to access into the hydrophilic dextran solution caused by the space in the mass effect, increases the basic subunits of soy 11S globulin heat resistance together to suppress the thermal aggregation.