Thanh法提取7S、11S球蛋白功能特性的研究

以中豆36为原料,分别提取大豆分离蛋白(SPI)、7S、11S球蛋白,系统地比较了它们的功能性质的差异。结果表明:SPI、7S及11S的功能特性之间存在较大差异,11S球蛋白具有较强的凝胶性、吸油性和溶解度;7S球蛋白具有较高的持水性和乳化性。     

7S 伴大豆球蛋白及其糖基化产物对大豆11S 球蛋白热聚集的影响

研究7S 伴大豆球蛋白(β - 伴大豆球蛋白)及其糖基化产物对大豆11S 球蛋白热聚集的影响。从浊度、ξ -电位、粒度、SDS-PAGE 测定得出在30mmol/L Tris-HCl 缓冲溶液中(含β - 巯基乙醇),7S 球蛋白及其糖基化产物能够抑制11S 球蛋白的热聚集,并且糖基化产物的抑制效果比未糖基化的7S 球蛋白明显;7S 球蛋白及其糖基化产物抑制11S 球蛋白热聚集的机理不同,7S 球蛋白糖基化产物对11S 球蛋白热聚集的抑制不是由于电荷的作用。     

11S/7S比例对大豆蛋白膜性能的影响

以自制的11S球蛋白、7S球蛋白以及商业化大豆蛋白(GS5000)为原料制备不同11S/7S比例大豆蛋白膜。通过比较膜的抗张强度、断裂延伸率、水蒸气透过率、水分含量、总可溶性物质和透光率等性质,研究11S/7S比例对大豆蛋白膜机械性能和阻隔性能的影响。结果表明,11S球蛋白含量高的膜具有较高的抗拉强度和在水中较高的稳定性,而7S球蛋白含量高的膜具有较高的断裂延伸率和较高的透明度。11S/7S比例对于大豆蛋白膜水蒸气透过率没有显著影响。     

pH对大豆7S、11S球蛋白功能特性影响

通过pH对大豆7S、11S球蛋白影响进行比较和分析,结果表明,随pH变化,大豆7S、11S球蛋白溶解度和乳化性变化趋势相同,即在等电点处值最小,偏离等电点区域则逐渐增大;且起泡性和起泡稳定性随pH升高呈上升趋势;而乳化稳定性则随pH升高呈下降趋势。     

添加不同配比7S/11S大豆球蛋白对鸡肉丸品质的影响

从大豆蛋白中分离出7S、11S大豆球蛋白,根据7S与11S球蛋白不同的蛋白质功能性质,通过不同的比例配比,添加至鸡肉丸中,考察7S/11S(质量比)大豆球蛋白不同配比对鸡肉丸蒸煮损失、颜色、硬度、弹性、自旋-自旋弛豫时间(T_2)时间变化以及感官特征的影响。结果表明:随着7S/11S比值的增大,鸡肉丸的蒸煮损失显著降低(P0.05),亮度值显著增加(P0.05)、硬度和弹性以及结合水的能力也显著增强(P0.05)。当7S/11S比值为4∶1时,蒸煮损失降低至最低2.13%(P0.05),此时肉丸的亮度值达到最大值51.85,肉丸的硬度、弹性、咀嚼性、胶黏性和回复性显著增强(P0.05),并具有良好的感官评分。     

纳米SiO2与尿素修饰大豆7S与11S球蛋白胶黏特性的研究

以大豆7S和11S球蛋白为研究对象,采用纳米二氧化硅(SiO2)对其进行分子修饰,添加量分别为蛋白基料的0.5%、1.0%、1.5%,然后用1、3、5 mol/L尿素控制变性相结合的方法来提高7S与11S球蛋白在3种木材(水曲柳、樱桃木、松木)上的胶黏强度。结果表明,经纳米SiO2修饰后,大豆7S和11S球蛋白的胶黏强度明显增大,最佳添加量为1%;当浓度为1 mol/L的尿素与1%的纳米SiO2共同修饰7S和11S球蛋白后,其胶黏强度最大。同时采用差示扫描量热仪测定了大豆球蛋白修饰前后的焓变,并探讨了胶黏作用增强的可能机理。     

不同处理方法对分离7S、11S中抗原含量的影响

7S和11S是大豆的主要球蛋白,两者占全蛋白的70%。GlymBd30K、GlymBd28K和β-伴大豆球蛋白(7S球蛋白)的α-亚基(MW68k)是大豆中的主要致敏蛋白。本文主要用三种缓冲液的不同处理方法分离7S、11S,使大豆的主要致敏蛋白尽量少的存在于分离后的11S组分中,而主要集中在分离后的7S组分中。豆腐的硬度主要依赖于11S球蛋白,因此这为大豆蛋白脱敏的同时仍能保有良好的凝胶形成能力提供新思路。     

7S和11S大豆球蛋白的分离研究

本研究选择低温脱脂大豆粕为原料,提出并采用碱提酸沉膜分离法来分离7S和11S大豆球蛋白,通过SDS-PAGE电泳鉴定分离纯度,并与传统的几种方法比较分离效果.结果表明,碱提酸沉膜分离法的分离效果明显优于传统的方法,所得的7S和11S大豆球蛋白的纯度可以分别达到75.5%和84.7%.     

大豆7S与11S球蛋白分离方法的研究

文章就提取分离低温脱脂大豆粕中大豆7S和11S球蛋白的方法进行了研究.利用SDS-PAGE凝胶电泳来评定不同pH值对分离大豆7S球蛋白和大豆11S球蛋白的纯度的影响.实验结果表明,浸提大豆蛋白的最佳工艺参数为磷酸盐缓冲液浓度为0.02 mol/L、料液比1∶16、浸泡温度45 ℃、pH值为8.5,可得到最高浸提率为89.55%.分离大豆11S球蛋白的最适pH值为6.2,纯度达75.76%;分离大豆7S球蛋白的最适pH值为4.7,纯度达72.99%.     

超声波辅助不同反胶束体系前萃7S和11S球蛋白的研究

主要研究了利用3种反胶束体系萃取7S、11S球蛋白,考查了缓冲溶液pH、WO、萃取温度、萃取时间等4因素对蛋白前萃率的影响规律,通过对3种反胶束体系提取7S、11S球蛋白的比较,筛选出最适于7S、11S蛋白的提取方法。在相同的条件下,AOT、CAB反胶束体系对大豆7S球蛋白的提取率一般高于对大豆11S球蛋白的提取率;而SDS反胶束体系对大豆7S球蛋白的提取率一般低于对11S球蛋白的提取率。为今后研究不同分子量大小的蛋白与反胶束"水池"微观结构相互关系的规律奠定基础。     

Effects of AOT reverse micelle on properties of soy globulins

This study was focused on the influence of AOT reverse micelle on physical–chemical properties of 7S and 11S globulins from soy proteins, and compared with aqueous buffer extraction. The results showed that the contents of the surface hydrophobicity and SH groups of 7S and 11S globulins and SS bonds of 11S globulin, using AOT reverse micelle extraction, were augmented, and SS bonds of 7S globulin decreased. The thermal and rheological properties of 7S and 11S globulins extracted using the two methods were studied by differential scanning calorimetry (DSC) and rheometery. It was found that the peak denaturation temperature and heat of transition of 7S and 11S globulins with aqueous buffer extraction were different from that with AOT reverse micellar extraction. The AOT reverse micelle did not affect the gel properties of 11S globulin, while it influenced 7S globulin’s. Hardness, springiness, gumminess, adhesiveness and chewiness of 7S globulin from AOT reverse micelle were lower than that from aqueous buffer extraction, but gumminess was higher.     

Heat‐induced denaturation impairs digestibility of legume (Phaseolus vulgaris L and Vicia faba L) 7S and 11S globulins in the small intestine of rat

7S globulin from common bean (Phaseolus vulgaris L) and 11S globulin from faba bean (Vicia faba L) were isolated to over 90% purity and the digestibility of the proteins, either in native or denatured (120 °C, 20 min, 1 atm) state, was tested in the small intestine of growing rats in acute (1 h) experiments. Native globulins were well digested (92 and 95% for 7S and 11S proteins, respectively). However, after thermal denaturation, protein digestibility of 7S globulin was reduced to 88%, while that of 11S globulin to only 79%. SDS‐PAGE revealed that high amounts of the intermediate proteolytic products of phaseolin (MW 22 000–27 000 Da) were present in the small intestine of rats after 1 h digestion of the denatured 7S globulin, while protein material in the high MW range (>55 000 Da) were recovered from the 11S globulin. The overall negative charge of unavailable proteins from the 7S globulin was found by anion exchange–FPLC separation to be higher than that of products from the 11S globulin. MALDI‐MS analysis of proteins in the small intestine confirmed the presence of half‐size phaseolin subunits (MW 23 700 Da) as breakdown products from the denatured 7S globulin, and of highly hydrophobic basic subunits (MW 20 000 Da) from the 11S globulin. Copyright © 2004 Society of Chemical Industry     

Purification and characterisation of the 7S globulin storage protein from sesame (Sesamum indicum L.)

The 7S globulin from sesame seeds was purified by means of selective precipitation and anion-exchange chromatography on Q Sepharose Fast Flow. The 7S globulin migrated as a single band on native PAGE, which suggested homogeneity of the sample. The isolated protein was composed of at least eight polypeptide chains, ranging from 12.4 to 65.5 kDa, judged by SDS–PAGE analysis, and did not contain disulphide bonds. Furthermore, comparison of the polypeptide bands of the 7S and 11S globulins by SDS–PAGE indicated that the purified 7S globulin was free of legumin-like contaminant polypeptides and of 2S albumin. The identity of the purified polypeptides was verified by comparing the N-terminal amino acid sequences of the main polypeptide bands with the amino acid sequence deduced from a cDNA clone, which encoded the sesame 7S globulin precursor. Purification of the 7S globulin from sesame has not previously been reported.     

大豆7S和11S球蛋白的结构和功能性质

主要介绍大豆７Ｓ和１１Ｓ球蛋白的结构和功能性质，大豆蛋白质各个成分的分子量有所不同，按超速离心分离系数可分为２Ｓ，７Ｓ１１Ｓ和１５Ｓ４个组份。７Ｓ组份占总蛋白质的３０．９％，它是由４种不同大豆蛋白民组成，１１Ｓ组份占总大豆蛋白质的４１％，而且都是单一的１１Ｓ球蛋白，１１Ｓ球蛋白的等电点为ｐＨ４．６４。     

Structural and Functional Analysis of Various Globulin Proteins from Soy Seed

Storage proteins of soybean mostly consist of globulins, which are classified according to their sedimentation coefficient. Among 4 major types: 2S, 7S, 11S, and 15S of globulins, 7S and 11S constitute major fraction. The 11S fraction consists only of glycinin and 7S fraction majorly consists of β-conglycinin, small amounts of γ-conglycinin and basic 7S globulin (Bg7S). Glycinin exist as a hexamer while β-conglycinin as a trimer and Bg7S as a tetramer. Glycinin subunits are coded by 5 genes of a family, whereas about 15 genes are present for β-conglycinin subunits. Bg7S gene is present in four copies in soybean genome. Synthesis of all proteins takes place as a single polypeptide chain, which is cleaved after folding to yield different chains or subunits. Glycinin and β-Conglycinin are made for storage purpose. However, Bg7S has potential xylanase inhibition activity and protein kinase activity. Primary structure of Bg7S reveals 12 conserved cysteine residues involved in forming 6 disulfide bonds, which provides appreciable stability to protein. Secondary structure is predominately rich in β-sheets with few alpha helices. Bg7S shares structural similarity with various aspartic-proteases. In this review, our aim is to discuss sequence, structure, and function of various globulins present in Glycine max.     

Isolation and partial characterization of proteins from pea (Pisum sativum L.)

Pea flour with a protein content (Nx6,25) of 25% was subjected to an extraction by 10% NaCl. The changes of the meal particles during the extraction were studied by electron microscopy. 89% of the nitrogen substances were extracted, 14% of which are albumins The nitrogen solubility curve of the meal has a minimum of 18% solubility at pH 4-5 The proteins in the NaCl extract were fractionated using dialysis (separation of globulins and albumins) and preparative gel chromatography (separation of the 11 S and 7 S globulins). The 11 S and 7 S globulins were homogenous in gel chromatography and ultracentrifugation. Their sedimentation coefficients s⁰_{20 w} were 11,9 S and 6,4 S, respectively. They differ significantly in the gel electrophoresis The amino acid composition of the isolated globulins shows a relatively high content of glutamin and aspartic acid as well as arginine and a lack of sulphur containing amino acids which are limiting. EAA indices of 69, 63, 62, 32 and 78 were calculated for pea flour, the raw globulin fraction, the 11 S and 7 S fraction, and the albumine fraction, respectively. Therefore for preserving the nutritive value of the pea material preparation processes are to be applied which exclude the loss of albumins during the protein isolation.     

Differential scanning calorimetry of lupin and soy proteins

Differential scanning calorimetry (DSC) was used to study the 7S and 11S globulin fractions extracted from lupin seed (Lupinus luteus) flour. In agreement with previous work on other lupin species, the isolate showed three denaturation peaks compared to the two observed with soy. By comparison with the isolated globulin fractions, the denaturation peaks at the two higher temperatures in the lupin isolate were assigned to the 11S and 7S globulins. The denaturation temperature of the lupin 7S globulin was about 10 K higher than that for the corresponding soy globulin, whereas the values for the 11S globulin were similar. All globulins displayed increasing thermal stability with decreasing moisture contents. Possible reasons for the differences in behaviour of soy and lupin protein isolates are discussed.     

Effect of reverse micelle on conformation of soy globulins: A Raman study

Raman spectroscopy was applied to investigate the main and side chain conformational changes of 7S and 11S globulins from soybean proteins using aqueous buffer and reverse micelle extraction. The 7S and 11S globulins using two extraction methods displayed typical spectral features (such as amide I, III region and the side chain conformations of particular residues) due to characteristic amino acid composition and molecular conformation. In comparison, the degree of molecular disorder increased in both globulins using reverse micelle extraction and new bands appeared. The relative amount of different structures of 7S and 11S globulins could be estimated through accurate measurement of the band intensities. Finally, the increase of the I_850/830 intensity ratio of Raman tyrosine doublet in 11S globulin with reverse micelle extraction suggested a change towards a more exposed state of tyrosine residues, in good agreement with the more disordered conformation taken upon reverse micelle.