大豆7S球蛋白与葡聚糖共价键合纳米凝胶的制备与表征

基于蛋白质与多糖的Maillard反应与自组装制备一种新型的绿色的具备核壳结构的纳米凝胶。利用干热反应制备大豆7S球蛋白与葡聚糖的共价接枝物(soy β-conglycinin-dextran conjugates,SDC),通过对SDC热处理使其自组装成大豆7S球蛋白-葡聚糖纳米凝胶(soy β-conglycinin-dextran nanogels,SDN),对其形貌、结构及性质进行分析,并利用多糖的空间位阻效应抑制蛋白质宏观过度聚集的理论指导,探讨尺寸均一SDN的形成机制。形貌学与zeta电位分析表明SDN为具备核壳结构的球状粒子,其外壳由亲水性的葡聚糖构成,内核由凝胶化的蛋白构成;表面疏水性分析表明内核蛋白的三级结构发生转变,疏水基团暴露,从而形成多个疏水空腔;稳定性分析表明SDN具有高度的pH稳定性与储存稳定性,对疏水活性物质的输送载体构建具有重要的借鉴意义。     

分子动力学模拟研究两亲聚合物与疏水纳米粒子自组装核-壳结构

基于Martini力场采用粗粒化分子动力学模拟研究了Pluronic嵌段共聚合物在疏水纳米表面自组装膜结构,考察了Pluronic嵌段共聚合物结构对自组装单分子膜结构的影响。模拟结果发现Pluronic聚合物在疏水纳米表面自组装形成了以纳米材料为核,聚合物为壳的特殊核-壳结构。聚合物的浓度和结构都会影响该壳层结构,在浓度较低时,聚合物EO嵌段卷曲地附着在疏水纳米颗粒表面,类似形成层状的壳层结构;随着浓度的提高,EO嵌段伸向溶剂相,形成星形自组装膜结构。增加Pluronic共聚物相对分子质量,吸附在纳米材料的聚合物壳层厚度也逐渐增加。随着聚合物PO摩尔的增加,吸附在纳米材料表面的PO嵌段由“S”形或“W”形吸附逐渐变成“U”形吸附。这可能因为随着聚合物浓度的提高,有限的纳米颗粒表面不足以提供足够多的吸附位点导致聚合物吸附构型转变。     

分子动力学模拟研究两亲聚合物与疏水纳米粒子自组装核-壳结构

基于Martini力场采用粗粒化分子动力学模拟研究了Pluronic嵌段共聚合物在疏水纳米表面自组装膜结构,考察了Pluronic嵌段共聚合物结构对自组装单分子膜结构的影响。模拟结果发现Pluronic聚合物在疏水纳米表面自组装形成了以纳米材料为核,聚合物为壳的特殊核-壳结构。聚合物的浓度和结构都会影响该壳层结构,在浓度较低时,聚合物EO嵌段卷曲地附着在疏水纳米颗粒表面,类似形成层状的壳层结构;随着浓度的提高,EO嵌段伸向溶剂相,形成星形自组装膜结构。增加Pluronic共聚物相对分子质量,吸附在纳米材料的聚合物壳层厚度也逐渐增加。随着聚合物PO摩尔的增加,吸附在纳米材料表面的PO嵌段由"S"形或"W"形吸附逐渐变成"U"形吸附。这可能因为随着聚合物浓度的提高,有限的纳米颗粒表面不足以提供足够多的吸附位点导致聚合物吸附构型转变。     

多糖的共价键合对7S球蛋白凝胶性能的影响

引入细胞学说中的大分子拥挤体系并在该体系通过Maillard反应制备了大豆7S球蛋白（β-conglycinin,7S）和葡聚糖（dextran,Dex）的共价复合物,利用转谷氨酰胺酶（transglutaminase,TGase）的交联作用制得蛋白-多糖共价复合物凝胶。对其流变学、质构特性及微结构进行分析。结果表明,在大分子拥挤环境下,7S-葡聚糖比例为2：1的共价复合物制得具有致密且孔洞分布均匀的凝胶网络结构。单纯的蛋白自聚集或者与多糖的共混状态时形成的凝胶弹性模量都较高,但蛋白过度的聚集并不能得到孔洞均匀的凝胶网络结构,共价复合物制备的凝胶中葡聚糖的共价键合作用抑制了TGase交联过程中蛋白质分子间发生过度的相互作用。形貌学观察表明,共价复合物制备的凝胶形成了网络孔径均匀且非常致密的凝胶网络结构。     

多糖的共价键合对7S球蛋白凝胶性能的影响

引入细胞学说中的大分子拥挤体系并在该体系通过Maillard反应制备了大豆7S球蛋白(b-conglycinin,7S)和葡聚糖(dextran,Dex)的共价复合物,利用转谷氨酰胺酶(transglutaminase,TGase)的交联作用制得蛋白-多糖共价复合物凝胶.对其流变学、质构特性及微结构进行分析.结果表明,在大分子拥挤环境下,7S-葡聚糖比例为2:1的共价复合物制得具有致密且孔洞分布均匀的凝胶网络结构.单纯的蛋白自聚集或者与多糖的共混状态时形成的凝胶弹性模量都较高,但蛋白过度的聚集并不能得到孔洞均匀的凝胶网络结构,共价复合物制备的凝胶中葡聚糖的共价键合作用抑制了TGase交联过程中蛋白质分子间发生过度的相互作用.形貌学观察表明,共价复合物制备的凝胶形成了网络孔径均匀且非常致密的凝胶网络结构.     

相关中国专利

专利名称:一种核壳结构烟用爆珠及其制备方法 专利申请号:202011111851.5 公开号:CN112021652A 申请日:2020.10.16 公开日:2020.12.04 申请人:河南中烟工业有限责任公司 本发明介绍一种核壳结构烟用爆珠及其制备方法,以混合水溶性香精的亲水性多糖为内核,疏水性蛋白质为外壳,通过反...     

核壳纳米材料的研究进展

综述了核壳纳米结构材料的制备方法,主要包括溶胶凝胶法、原位聚合包覆法、异相凝集法、声化学法、乳液聚合法和层层自组装法等,介绍了核壳纳米结构材料的性能特点,并展望了核壳纳米材料的应用前景。     

微波水热法制备CdS微晶球及S/CdS核壳结构

以氯化镉和硫代硫酸钠为起始原料采用微波水热法(M-H)制备了CdS微晶球和S/CdS核壳结构.采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和EDS能谱对制备的CdS微晶球和S/CdS核壳结构进行表征.结果表明:在微波水热条件下,棒状S经自组装而形成直径为20 μm的圆盘核结构,经化学吸附组装,直径为1 μm左右的CdS微晶球吸附于S圆盘核的周围,形成了S/CdS核壳结构;CdS微晶球具有分级结构,是由纳米球组装而成的微晶球.     

核-壳结构二氧化硅介孔材料的制备与表征

采用溶胶凝胶法在一定条件下合成了具有核-壳结构的二氧化硅介孔材料,使用透射电子显微镜对微球样品的超微结构进行了观察,使用傅里叶红外光谱分析了样品的光谱性质。分析结果表明:制备的核-壳结构介孔二氧化硅微球样品,是由外表面为孔径约8纳米,厚度约30纳米的有序介孔二氧化硅壳层,包裹着内核为直径约200纳米的二氧化硅微球所组成,介孔壳层具有较大的比表面积,具有良好的光谱性质。     

葡聚糖对大豆7S球蛋白的物性修饰

通过大分子拥挤环境下液相体系中发生Maillard反应制备大豆7S球蛋白-葡聚糖共价复合物,采用十二烷基磺酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)技术证实大豆7S球蛋白和葡聚糖发生了共价结合。采用凝胶渗透色谱(GPC)、哈克流变仪、荧光分光光度计、紫外可见分光光度计系统研究了共价复合物的形成及葡聚糖共价键入后对蛋白特性的影响。结果表明：5%的7S球蛋白与15%的葡聚糖在pH7.0条件下,95℃反应6 h得到的产物接枝度较高,大豆7S球蛋白和葡聚糖形成了大分子的共价复合物,产物乳化活性提升了约221.7%。     

Pilot-plant fractionation of soybean glycinin and β-conglycinin

A laboratory process for separating glycinin and β-conglycinin from soybean flakes was successfully scaled up to the pilot-plant scale (15 kg soy flakes). Average yields of the glycinin and β-conglycinin fractions were both 9.4% on a dry basis (db). The protein contents of glycinin and β-conglycinin fractions were 92.8 and 97.7% db, respectively. The glycinin and β-conglycinin purities were 90.4 and 72.7% of the protein content, respectively, which were very comparable to those of the laboratory-scale process. The total sulfhydryl plus half cystine content of the glycinin fraction was 37.8 mol/mol protein and 14.8 mol/mol protein for the β-conglycinin fraction. The native glycinin structure loss in the glycinin fraction was negligible. The native β-conglycinin loss in the β-conglycinin fraction was 10%, as estimated by rocket immunoelectrophoresis analysis. Hydrophobicity index value showed that hydrophobic properties of the pilot-plant protein fraction were ordered, from high to low: β-conglycinin fraction > glycinin fraction > intermediate mixture fraction.     

Physicochemical Properties of Soy Protein Adhesives Obtained by In Situ Sodium Bisulfite Modification During Acid Precipitation

Successful industrial applications of soy protein adhesives require high adhesion strength and low viscosity at high solid protein concentration. This study examined the effects of β-conglycinin (7S) and glycinin (11S) ratios on the physicochemical properties of soy protein adhesives. Soy protein adhesives with various 7S/11S ratios were extracted from soy flour slurry modified with sodium bisulfite using the acid precipitation method, which is based on the different solubilities of 7S and 11S globulins. Seven glycinin-rich soy protein fractions and six β-conglycinin-rich soy protein fractions were obtained. The external morphology of the samples changed from the viscous cohesive phase to the clay-like phase without cohesiveness. The viscous cohesive samples had good flowability and good water resistance with a wet adhesion strength of 2.0–2.8 MPa. They were stable for up to several months without phase separation at room temperature. Based on the results, we suggest that proper protein–protein interaction, hydration capacity (glycinin-rich soy protein fractions), and certain ratios of 7S and 11S (β-conglycinin rich soy protein fractions) in the soy protein sample are crucial to continuous protein phase formation. Hydrogen bonding, electrostatic forces, and hydrophobic interactions are involved in maintaining the protein viscous cohesive network, whereas disulfide bonds do not exert significant effects. This study describes a new way to investigate viscous cohesive soy protein systems with high solid protein content, thus alleviating the disadvantages of traditional methods for studying the adhesive properties of soy protein isolates, which tend to have poor water resistance, low solid contents, and short storage life.     

Sodium Bisulfite-Induced Changes in the Physicochemical,Surface and Adhesive Properties of Soy β-Conglycinin

The effects of sodium bisulfite on the electrophoresis profile; turbidity; and thermal, surface, and adhesive properties of soy β-conglycinin protein were studied. Sodium bisulfite dissociated high-molecular-weight aggregates in the protein, and the aggregate percentage decreased with increasing sodium bisulfite concentration. Denaturation temperature of sodium-bisulfite-treated β-conglycinin increased as sodium bisulfite increased. However, at high sodium bisulfite concentration (i.e. 36 g/L), denaturation enthalpy decreased significantly. Sodium bisulfite caused changes in the β-conglycinin secondary structure and promoted ionization of lysine residues as indicated by FT-IR results. A sudden drop in turbidity at pH 4.8 was observed at the same salt level. The contact angle of β-conglycinin on cherry wood reached its minimum at 6 g/L sodium bisulfite and 24 g/L on glass. Water resistance of β-conglycinin was improved but not significantly by 6 g/L sodium bisulfite at pH 9.5. An obvious increase in adhesion strength of the protein occurred at 3 and 6 g/L sodium bisulfite at pH 4.8. A high sodium bisulfite concentration at 36 g/L sharply reduced the adhesive performance of β-conglycinin.     

Potential β-sheet surfaces of soybean seed proteins

Volume and amphiphilicity profiles computed for β-sheet conformations of soybean seed proteins (the acidic and basic subunits of glycinin, the α subunit of β-conglycinin, an extensin-like high-proline protein, and a lipid body oleosin) were compared to profiles for selected nonseed proteins and random-sequence polypeptides. The major soy proteins resemble fibrinogen more than silk or collagen but are differentiated from each other by surface polarity. Polarity in acidic glycinin fluctuates somewhat regularly and symmetrically along both sides of the β-sheet, but in basic glycinin, polarity on one side is fourfold that on the other throughout 70% of the protein. Polar residues distribute equally on either side of the β-conglycinin subunit, but half of the acidic and basic residues concentrate in the N-terminal third of the molecule. The remainder of the β-conglycinin contains 90% of the molecule’s tyrosine, of which 70% is along one side. In the high-proline protein, 90% of the tyrosine distributes to one side of a β-sheet; 95% of the acidic residues to the other. Only soy oleosin approximates the per-residue volume, polarity, and uniformity of silk or collagen. Its 85-residue central lipophilic domain is much less polar than silk and nearly as uniform.     

Chemical coating polysaccharide on gigaporous polystyrene microspheres as a high‐speed protein chromatography matrix

Permanent polysaccharide coating on gigaporous polystyrene (PS) microspheres was achieved through direct chemical grafting of dextran via a facile method, minimizing nonspecific adsorption of proteins and providing easily derivatizable groups on microspheres. Chloroacetylated PS microspheres (PS‐Cl) were first developed through acetylation, and hydrophilic dextran was directly grafted to hydrophobic PS‐Cl via a Williamson reaction (PS‐Dex). The homogeneous side‐bound dextran coating has the advantage of masking the hydrophobic surface of the PS microspheres, while maintains their original gigaporous structure. After grafting, the hydrophobic surface of the PS microspheres was effectively masked, and nonspecific protein adsorption was greatly reduced. Moreover, the hydroxyl‐rich coating can be easily derivatized through classical chemical methods. A column packed with PS‐Dex presented both good permeability and mechanical strength at high flow velocities of up to 3612 cm/h. These results implied that PS‐Dex should be an ideal matrix for high‐speed protein chromatography. POLYM. ENG. SCI., 56:1407–1414, 2016. © 2016 Society of Plastics Engineers     

Functional properties of protein ingredients prepared from high-sucrose/low-stachyose soybeans

High-sucrose/low-stachyose (HS/LS) soybeans were used to prepare ethanol-washed soy protein concentrate (EWSPC), soy protein isolate (SPI), and a new low-fiber soy protein concentrate (LFSPC) in which the protein was extracted with alkali to remove fiber and the protein extract was neutralized and freeze-dired. LFSPC prepared from HS/LS soybeans contained significantly higher ratios of β-conglycinin to glycinin (1∶1.32) than did EWSPC (1∶1.75) or SPI (1∶1.69), which may have affected functional properties. The LFSPC were also high in soluble sugars (14.7%) and low in fiber (0.3%) compared with traditional EWSPC (2.9 and 3.4%, respectively) and SPI (1.8 and 0.3%, respectively). For both normal and HS/LS soybean varieties, the LFSPC, especially when extracted at pH 7.5 as opposed to pH 8.5, had higher denaturation enthalpies than did EWSPC and SPI, indicating less denaturation had occurred. Water solubilities, surface hydrophobicities, and emulsification properties were highest for the LFSPC and lowest for EWSPC. The LFSPC also had good foaming properties and low viscosities. These desirable functional properties of the LFSPC make them unique among alternative soy protein ingredients and highly suitable for industrial applications as food additives and ingredients.     

The influence of genotypic variation in protein composition on emulsifying properties of soy proteins

This study describes the relationship between the emulsifying properties of soybean proteins and their composition, i.e., glycinin (11S) and β-conglycinin (7S). Twelve investigated soybean genotypes showed significant differences in storage protein composition. The β-conglycinin concentration positively correlated with extractable soluble protein content, which was positively correlated with protein extractability. These data suggest that the level of β-conglycinin has a positive influence on protein extractability. The emulsion activity index (EAI) was strongly and positively correlated with the 11S∶7S ratio and strongly and negatively correlated with the concentration of β-conglycinin. The emulsion stability index (ESI) showed a moderate positive correlation with the monomeric form of glycinin and a strong positive correlation with the ratio of the monomeric to dimeric form of glycinin. No association was evident between ESI and EAI. Also, no relationship was found between ESI or EAI and extractability. Based on these data, it appears that the 11S∶7S ratio strongly reflects the ability of soybean proteins to form emulsions, whereas the ratio of the two different forms of glycinin may be crucial factors for the stability of soybean protein emulsions. Thus, understanding the relationship between protein composition and functionality could be useful for further improvement of functional behavior of soy proteins in food systems.     

Characterization of Fractionated Soy Proteins Produced by a New Simplified Procedure

It was possible to fractionate soy protein into two soy protein isolate fractions (>90% protein) enriched in either glycinin or β-conglycinin by using a new simplified procedure (referred to as the Deak procedure) employing CaCl₂ and NaHSO₃. The Deak procedure produced fractions with higher yields of solids, protein, and isoflavones, and similar protein purities as well as improved functional properties compared to fractions recovered by established, more complex soy protein fractionation procedures. The Deak glycinin-rich fraction comprised 15.5% of the solids, 24.4% of the protein, and 20.5% of the isoflavones in the starting soy flour, whereas the glycinin-rich fraction of the established procedure (Wu procedure) comprised only 11.6% of the solids, 22.3% of the protein, and 9.6% of the isoflavones. The Deak β-conglycinin-rich fraction comprised 23.1% of the solids, 37.1% of the protein, and 37.5% of the isoflavones in the starting soy flour, whereas the Wu β-conglycinin-rich fraction comprised only 11.5% of the solids, 18.5% of the protein, and 3.3% of the isoflavones. Protein purities were >80% for both fractions when using both procedures. The Wu procedure produced protein fractions with slightly higher solubilities and similar surface hydrophobicities; whereas, the fractions produced by the Deak procedure had superior emulsification and foaming properties and similar dynamic viscosity behaviors.