Study On The Mechanism Of The Interaction Of Catechol And Resorcinol With Bovine Serum Protein And Myosin

Fucoidan is a polymer of resorcinol extracted from Fucoidan.It has been previously proved that Fucoidan can improve the gel strength of surimi gel.In order to further study the reaction mechanism between brown algae polyphenols and proteins,this article first selects its monomer phenol-resorcinol(MP)as the research object.Resorcinol has not been studied for its reaction with proteins due to its structural characteristics.At the same time,we have selected catechol(OP),which has a similar structure to resorcinol,for comparison.The protein that plays a major role in surimi gel is myoglobin(Myo).Due to its structural complexity,we first select bovine serum protein(BSA)as the main protein reference.BSA is a sphere with a higher molecular weight.Protein,and can form soluble complexes with phenolic compounds,suitable for the study of such mechanisms.On this basis,myosin was selected as the research object.Changes in the free amino content of a protein can reflect chemical changes that occur in the protein.This article first studied the analytical conditions of trinitrobenzenesulfonic acid(TNBS)method to determine the free amino content of protein,and the results showed that the accuracy of the analysis of basic termination reaction conditions using UV-visible absorption spectroscopy is high,and the type of protein not only affects the method.The concentration is sampled and the disulfide bonds in the protein interfere with the accuracy of the method.Secondly,two methods for monitoring the oxidation degree of phenolic compounds were determined,and the preparation method of phenolic compoundprotein complex was selected.The Folin-Ciocalteu method and UV-Vis absorption spectroscopy were used to monitor the oxidation process of OP and MP.Two preparation methods were used to react oxidized and anoxic OP,MP and BSA to prepare phenolic compound-protein complexes.The feasibility of the two preparation methods was evaluated by measuring the changes in the free amino content of BSA before and after the reaction.The results show that OP and MP can be oxidized and polymerized under alkaline conditions(p H 9)in the presence of oxygen.Compared with the Folin-Ciocalteu method,UV-Vis absorption spectroscopy can accurately monitor the oxidation degree of OP and MP.Oxidation at 25 ? for 24 hours can completely oxidize.The oxidized OP and MP can reduce the free amino content of BSA.The best preparation method is to oxidize OP and MP first and then react with BSA.In order to study the mechanism of the interaction between phenolic compounds and proteins,oxidized catechol(OOP),resorcinol(OMP)and unoxidized OP,MP and BSA,Myo were reacted at 25 ° C.Analyze changes in free amino groups,thiol groups,and surface hydrophobicity before and after BSA and Myo react with oxidized and unoxidized OP and MP;changes in non-covalent interaction forces between proteins before and after BSA,OP,and MP reactions;apply Fourier Leaf transformation infrared spectroscopy(FTIR),circular dichroism(CD),and differential scanning calorimetry(DSC)were used to characterize changes in protein conformation.The results show that after the interaction of BSA and Myo with OP and MP,the content of free amino groups and thiol groups does not change significantly,but OOP and OMP can significantly reduce the content of free amino and thiol groups in BSA and Myo,and the reduction of OOP-BSA is greater than OMP-BSA.OP,MP,OOP,OMP will significantly reduce the surface hydrophobicity of BSA and Myo,and the reduction of OP-BSA,OOP-BSA is greater than MP-BSA,OMP-BSA,and the reduction of OP-Myo,OOP-Myo is less than MP-Myo,OMP-Myo,this difference is caused by the different structure of BSA,Myo.OP and MP have no significant effect on the ionic bonding of BSA,but will cause the hydrogen bonding of BSA to increase significantly,and the increase of MP-BSA is greater than that of OP-BSA;OP can significantly increase the hydrophobic interaction of BSA,and MP causes hydrophobic Interactions were significantly reduced;FTIR and CD results showed that OP,MP,OOP,and OMP all lead to changes in the secondary structure of BSA.The ?-helix content in the four complexes is reduced,and the ?-sheet,?-turn,and random curl content The increase indicates that the combination of BSA with OP and MP destroys the secondary structure of BSA,and the impact of OP and OOP is greater than that of MP and OMP.DSC results show that the introduction of OP,MP,OOP,and OMP improves the degeneration of BSA.temperature.These results confirm that catechol and resorcinol can covalently and non-covalently interact with BSA and Myo.Finally,the role of phenolic compounds in the formation of surimi gel was simulated.The sample was heated in two stages: 40 ° C for 1 h,then 90 ° C for 30 min.The heat treatment of hydroquinone,resorcinol,and Impact of BSA interactions.By analyzing the changes in the content of free amino groups,thiol groups,surface hydrophobicity,non-covalent interaction forces,and changes in secondary structure of BSA and its complexes before and after heat treatment,the effects of heat treatment on the interaction between phenolic compounds and BSA were characterized.influences.The results show that the temperature increase promotes the oxidation of OP and MP.The oxidized products,that is,quinones,can covalently interact with the thiol and free amino groups of BSA,thus promoting the phenolic compounds and Covalent interaction of BSA;the increase in temperature promotes the covalent bonding of phenolic compounds and BSA hydrophobic amino acids And non-covalent reaction,making the surface hydrophobicity of BSA lower;heating has no significant effect on the ionic bond between OP,MP and BSA,which will cause the hydrogen bond content of OP-BSA,MP-BSA to be significantly reduced,and the hydrophobic interaction will be increased;The increase in temperature promotes the combination of phenolic compounds and BSA and the aggregation of BSA molecules,which changes the secondary structure of BSA.The main manifestations are reduced ?-helix content and increased random coil content.When the temperature reaches the BSA denaturation temperature The phenolic compounds inhibited the denaturation and aggregation of BSA to some extent.