Preparation And Functional Properties Of Silver Carp Myosin-konjac Glucomannan Complex

In this paper,the myosin protein?Ms?and konjac oligo-glucomannan?KOG?were used as the main materials,choosing glucose as a control,and Ms-saccharide glycoconjugates were obtained by using the controlled glycation.The physicochemical characteristics?conformation and functional properties of the glycoconjugates were studied systematacially in order to research the Ms-saccharide glycoconjugates modification,find the functional properties of the products,which could provide the basic theory for the industry in some degree.Konjac oligo-glucomannan?KOG?was prepared by degradation of konjac glucomannan?KG?using neutral?-mannanase.The hydrolysis process was monitored by the viscosity of the enzymatic hydrolysates.Factors affecting the enzymatic hydrolysis of KG were investigated,and the optimum hydrolysis conditions were as follows:time 2 h;temperature 50oC;pH 6.0;and enzymatic concentration 150 U/g.The results of Fourier transform infrared?FTIR?spectra of KG and KOG indicated that KG was successfully degraded.After Ms glycated with saccharide,the content of its saccharide rose obviously.Amino acid analysis indicated that lysine and arginine decreased significantly in the glycoconjugates.Formation of glycoconjugates reduced pI?the total SH content and H₀.While the heat-denaturalization temperature in it increased in some degree with the incubation time.According to the analysis of SDS-PAGE,the bands of the glycoconjugates exhibited a lower electrophoretic mobility,yielding a molecular weight noticeably higher than that of unglycated Ms.Furthermore,it was proved by FTIR that the Ms was glycated with saccharide by the covalent bond.It was observed with SEM that the surface structure of Ms was different with Ms-saccharide glycoconjugates,whose aggregates were dispersed,especially for the Ms-KOG conjugate.AFM images indicated that coarser and bigger structures of Ms-saccharide glycoconjugates were formed by glycation.In addition,because of the particle size of the glycoconjugates in the irregular set through dynamic laser scattering,this phenomenon reduced the aggregation of the protein molecule.In comparison with Ms,the content of?-helix conformation and the random structure in the second structure of Ms-saccharide glycoconjugates,which was detected by CD,decreased,but that of the?-strand and turn increased.In addition,by the analysis of intrinsic emission fluorescence spectroscopy,the fluorescence emission maximum??_m?of Ms-saccharide glycoconjugates suffered a red shift and the quantum yield of fluorescence decreased.In addition,as a new-type of saccharide with abundant hydrophilic groups and a certain amount of branches,Ms-KOG conjugate has a strong steric hindrance than Ms-glucose conjugate,thus the?_m of Ms-KOG conjugate suffered a red shift ahead of Ms-glucose conjugate and the quantum yield of fluorescence decreased more than that of Ms-glucose conjugate.The study also found that the solubility?especially in low salt-concentration solution?and heat stability of Ms-saccharide glycoconjugates were improved in comparison with Ms,and with the incubation time increased,emulsifying property?EAI and ESI?was firstly increases and then decreases.Furthermore,SDS-PAGE was used to qualitatively compare the digestibility of Ms before and after glycation,the digestion of Ms in the simulated gastric fluid and intestinal digestion increased significantly after glycation.In addition,the digestion of Ms occurred mainly in intestine.Using Ms-saccharide glycoconjugates to prepare protein film,the physical characteristics of the silm were studied in this paper.Compared with films prepared from Ms,films prepared from the glycoconjugates had darker color,lower moisture content?MC?and total water solubility?TSM?,better elongation and decreased water vapor permeability?WVP?.In addition,films prepared from the Ms-KOG conjugate had darker color,lower elongation,better stability in the water and tensile strength?Ts?and WVP compared with the film of Ms-glucose conjugate.This study showed that glycosylation of Ms with KOG could significantly improve the functional properties of Ms.And the mechanism of glycosylation of Ms for improvement of thermal stability was revealed.The results of this study will provide the scientific basis for the application of protein in food industries.