大豆7S球蛋白和11S球蛋白的研究

主要阐述了大豆7S球蛋白和11S球蛋白的分离富集方法及其主要特性。     

大豆7S球蛋白和11S球蛋白的研究

主要阐述了大豆 7S球蛋白和 1 1S球蛋白的分离富集方法及其主要特性。     

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。     

棉籽7S及12S球蛋白的分离纯化及其物化性质的研究

以棉籽贮存蛋白为原料,采用蛋白纯化系统(配备凝胶层析柱)对棉籽7S和12S球蛋白进行分离纯化,对所得7S和12S球蛋白的蛋白质含量、氨基酸组成、变性温度及荧光强度等物化性质进行了测定分析。结果表明:棉籽7S及12S球蛋白的蛋白质含量分别为(91.59±0.53)%和(93.35±0.62)%,其SDS-PAGE谱图中除显示各自特征条带外无其他杂带,其氨基酸组成与绝大部分油料种子中球蛋白的基本一致,含有丰富的谷氨酸、天冬氨酸和精氨酸,而半胱氨酸和甲硫氨酸含量较低;差示扫描量热仪(DSC)分析棉籽7S及12S球蛋白的变性温度分别为93.3℃和107.7℃;棉籽7S及12S球蛋白的荧光发射光谱最大荧光强度均在325 nm左右。     

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%.     

Saio法提取大豆7S球蛋白的纯化及鉴定

研究利用Sephadex G-200凝胶柱层析法和纤维素DE-52离子交换柱层析法分离纯化经过Saio法提取的大豆7S球蛋白样品,采用SDS-聚丙烯酰胺凝胶电泳和高效毛细管电泳进一步鉴定Saio法提取的大豆7S球蛋白样品的组分及含量。结果表明,Saio法提取的大豆7S球蛋白纯度约为81%。     

分离7S和11S大豆球蛋白简便方法

该文研究一种实验室直接分离7S和11S大豆球蛋白简便方法,并讨论影响分离效果的一些因素。发现在本方法中最适分离的pH值范围为6.2～6.4,Tris-HCl缓冲液浓度在不超过0.06M时有助于7S和11S球蛋白的分离,高蛋白质浓度(不大于4％)有利于7S和11S球蛋白分离,而NaCl浓度对这两种球蛋白分离影响比较复杂。     

不同工艺条件对大豆分离蛋白7S和11S组分影响的探讨

利用碱提酸沉的工艺，通过改变温度和离子强度得到不同参数条件下的大豆分离蛋白。经过凝胶电泳分析得到蛋白质的各个条带组分图，用图像捕捉成像技术以及相关软件，分析出分离蛋白各个组分的详细情况（包括组分数、分子量和各个组分所占的百分含量）。由实验可知，分离蛋白的7S和11S组分随温度和离子强度的改变而发生变化，分析其变化规律，从而确定合适的工艺参数。     

大豆分离蛋白中7S和11S大豆球蛋白的选择性酶解研究

使用胃蛋白酶在温度37℃,pH1.5～4.0范围内,以及木瓜蛋白酶在pH7.0,温度37～80℃范围内对大豆分离蛋白(SPI)进行水解,采用聚丙烯酰胺凝胶电泳技术对水解情况进行分析。结果表明,在37℃和pH1.5～2.5条件下,大豆分离蛋白中的11S大豆球蛋白被胃蛋白酶选择性地水解;在70℃,pH7.0条件下,7S大豆球蛋白被木瓜蛋白酶选择性地水解。      

制备方法对大豆7S和11S球蛋白的结构和热稳定性影响

大豆蛋白的主要组分是β-伴大豆球蛋白(7S)和大豆球蛋白(11S),加工方法不同将会对其结构与热稳定性产生重要的影响。文章采用扫描电镜(SEM)、X-射线衍射(XRD)、傅里叶红外光谱(FTIR)、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)及差示热量扫描仪(DSC)等方法对比研究了等电点沉淀法和等电点沉淀结合含促溶剂的反胶束法制备的大豆7S和11S球蛋白结构和热稳定性。结果表明,SEM图像显示2种提取方法制备的7S和11S球蛋白的整体微观结构及蛋白表面都存在显著差异(P<0.05);XRD检测发现2种方法制备的球蛋白骨架结构无显著差异(P>0.05),但含促溶剂的反胶束法可以修饰蛋白的无定形结构;FTIR分析发现含促溶剂的反胶束制备蛋白中β-转角含量较高,β-折叠含量较少;SDS-PAGE图谱显示含促溶剂的反胶束法更能保护蛋白分子的亚基结构,蛋白的纯度也更高;DSC结果展示含促溶剂的反胶束法制备的7S和11S球蛋白的热变性温度显著高于等电点沉淀法(P<0.05)。以上结果表明,等电点沉淀结合含促溶剂的反胶束法改变了7S和11S球蛋白结构和热稳定性,提取效果...     

芝麻菜种子抗菌蛋白的纯化及其抗菌活性

本文旨在从芝麻菜种子中分离纯化得到一种具有抗菌活性的蛋白,并对其抗菌活性进行研究。通过SP-Sepharose离子交换色谱、Mono S^TM 5/50GL和Superdex^TM 75 10/300GL快速蛋白液相色谱进行分离纯化,经Tricine-SDS-PAGE电泳分析;采用纸片扩散法、荧光染色法,对其抗菌活性和稳定性进行研究。结果表明,从芝麻菜种子中纯化一种抗菌蛋白ZSU2,经Tricine-SDS-PAGE电泳鉴定达到电泳纯,相对分子质量约为12 kDa;ZSU2蛋白对小白菜炭疽病菌等12种真菌具有较强的抑制作用,抗菌活性在pH1~13、温度0~100℃稳定,且具有较强的金属阳离子耐受能力;此外,ZSU2蛋白能引起菌丝尖端几丁质积累和细胞膜选择透过性的改变。     

Purification and characterization of a new 11S globulin-like protein from Chinese jujube (<Emphasis Type="Italic">Ziziphus jujube</Emphasis> Mill.) seeds

Around 8 million tons of jujube pomace containing seeds was produced each year in China; so how to utilize these residual matters has been receiving great attentions. The 11S globulins are the major storage proteins, and it can be used as additive agents in many food products with gelling and caking functionality. In the present study, an 11S globulin-like protein (ZSG) was isolated and purified from Chinese jujube (Ziziphus jujube Mill.) seeds by two consecutive anion exchange and size exclusion chromatography. A yield of 8 mg of the ZSG from 1 kg seeds was obtained. The apparent molecular mass of the native ZSG was found to be about 210 kDa. The protein consisted of two subunits with molecular masses of 26.0 kDa and 26.5 kDa, respectively. Amino acid composition analyses indicated that ZSG contained all eight essential amino acids, while lysine was the first limiting amino acids. N-terminal amino acid sequences of 26.0- and 26.5-kDa subunits are GVEETICTLRLLENI and GLEETVCSLRLKENI. The two peptide fragments of 26.0-kDa subunit are ANPDQVLENAFQISR and GVEETICTLR by LC–MS/MS. To the best of our knowledge, this is the first report on the purification of 11S globulin-like protein from Chinese jujube (Ziziphus jujube Mill.) seeds.     

大豆蛋白11S组分的分离方法研究

采用Nagano法结合电泳图谱ImageMaster 1 D Elite V4.00软件分析法,对大豆分离蛋白的11S组分进行了分离效果研究。确定最佳工艺参数组合为:酸沉pH值6.4、Ca2 浓度40mmol/L和冰浴时间5h。制得的样品中11S组分含量可以达到81.9%。     

Properties of Biopolymers from Cross-linking Whey Protein Isolate and Soybean 11S Globulin

Biopolymers were prepared by cross-linking whey protein isolate (WPI) and soybean 11S using transglutaminase. Electrophoretic pattern, solubility, emulsification, hydrophobicity and foaming properties of the biopolymers were determined. SDS-PAGE showed bands corresponding to high-molecular-weight components (MW>200 kDa). Biopolymer solubility was > 90% at pH 3 and below, and at pH 7 and above. Emulsifying properties of biopolymers were lower than those of WPI. The foaming capacity of the biopolymers (23.6 mL) and WPI/11S mixture (22.7 mL) were similar to that of egg albumin (20.3 mL). The foaming stability of the biopolymers (122 min) was higher than that of WPI/11S mixture (33.7 min), and was similar to that of egg albumin (132 min).     

大豆球蛋白11S/7S比值对大豆蛋白功能性的影响

大豆蛋白的功能特性与11S／7S比值密切相关。本研究中将llS和7S蛋白以不同比例混合(1lS／7S=0．5、1、1．5、2、2．5、3、3．5、4)，得到具有不同llS／7S比值的大豆蛋白，用SDS-PAGE凝胶电泳测定这些大豆蛋白的实际11S／7S比值分别为0．25、0．64、0．90、1．31、1．57、1．80、1．98、2．18、2．28、3．86。然后分析实际llS／7S比值对大豆蛋白乳化性、凝胶透明性和发泡性的影响，结果表明：大豆蛋白的乳化性、凝胶透明性和起泡性都随llS／7S比值的增加而降低。     

Antioxidant capacity and chemical constituents of Chinese jujube (Ziziphus jujuba Mill.) at different ripening stages

Chinese jujube (Ziziphus jujuba Mill.) is admired for its high nutritional value and has been commonly used in traditional Chinese medicine for its remarkable health functions. The antioxidant capacity (AOC) and the other qualitative parameters of jujube were measured at ripening stages of green maturity (GM), white maturity (WM), halfred maturity (HM), and red maturity (RM). AOC was screened with DPPH radical scavenging activity, Trolox equivalent antioxidant capacity, and reducing power. Jujube showed a significant (p<0.05) increase in the total soluble solids and titratable acidity, and firmness have no change of all maturity stages, while ascorbic acid showed a significant (p<0.05) declining trend. At stage of GM, the total phenolic content (TPC), total flavonoid content (TFC), and AOC in peel were the highest, and then rapidly decreased after WM. Meanwhile TPC and AOC in pulp reached a peak value in WM then declined, but TFC declined slowly during maturity.     

干制方式对鲜食枣食用及营养品质的影响

通过对微波真空冷冻干燥(microwave vacuum freeze drying,MVFD)、微波真空膨化(microwave vacuum puffing,MVP)、真空冷冻干燥(vacuum freeze drying,VFD)和中短波红外干燥(short-and medium-wave infrared drying,ID)4种干制加工的鲜食枣食用及营养品质进行分析,以期明确干制方式对鲜食枣营养特点的影响。结果表明:干制加工显著提高鲜食枣总糖、还原糖含量(P0.05),除ID外,干制后总酸含量均显著降低(P0.05),产品褐变程度低,糖酸比明显提高;MVFD对VC保留率高达98.62%;MVP和MVFD后总酚含量显著提高(P0.05),分别为4 721.30 mg/100 g(以干质量计,下同)和4 516.25 mg/100 g;VFD后黄酮含量增加到80.51 mg/100 g。微观结构方面,VFD鲜食枣密集多孔,呈蜂窝状;MVFD鲜食枣孔大均匀;MVP鲜食枣结构疏松,多小分子颗粒;ID鲜食枣紧实致密,无空腔结构。感官评定方面,MVFD和MVP对鲜食枣色泽、香气、口味和外形的综合评价接近于VFD。综合来看,MVFD和MVP对鲜食枣加工具有显著优势,且效率高成本低,应用前景广阔。     

Characterization of water soluble polysaccharides from organs of Chinese Jujube (<Emphasis Type="Italic">Ziziphus jujuba</Emphasis> Mill. cv. Dongzao)

Water-soluble polysaccharides (WSPs) in Chinese jujube leaves, fruits and flowers were extracted with hot water from the alcohol insoluble residues (AIRs) and precipitated with ethanol allowed to concentrate the fraction as 7.8, 5.1, 18.3%. Pectic polysaccharides were the major components in all WSPs since all extractions were very rich in sugars such as uronic acid, arabinose and galactose. Polymers extracted with hot water from different organs were different in the degree of branching, degree of esterification. All WSPs revealed immunobiological activities especially in fruits and flowers.     

Textural Characteristic,Antioxidant Activity,Sugar, Organic Acid,and Phenolic Profiles of 10 Promising Jujube (Ziziphus jujuba Mill.) Selections

Abstract: Ten promising jujubes were analyzed for textural characteristic (hardness), antioxidant activity, sugar, organic acid, and phenolic profiles. Total phenolic content (TP) measured by Folin–Ciocalteu method ranged from 275.6 to 541.8 mg of gallic acid equivalents per 100 g fresh weight (mg GAE/100 g FW). Four sugars (rhamnose, fructose, sucrose, and glucose), 3 organic acids (malic, citric, and succinic acids), and 11 phenolic compounds (gallic acid, protocatechuic acid, cinnamic acid, chlorogenic acid, caffeic acid, ferulic acid, ellagic acid, catechin, epicatechin, rutin, and quercetin) were identified and quantified by high‐performance liquid chromatography in jujube fruits. The results showed that ascorbic acid and proanthocyanidins contents were positively correlated with hardness, and antioxidant activity was well correlated with TP content. Among 10 jujube cultivars, Zizyphus jujuba cv. Qingjianmuzao is good for direct consumption containing high levels of total soluble solids, total sugars, fructose, and glucose, while Zizyphus jujuba cv. Jiaxianmuzao could be an important dietary source of natural antioxidants. Practical Application: Genotype is the main factor influencing the composition of bioactive compounds in jujubes. Zizyphus jujuba cv. Qingjianmuzao is good for direct consumption, while Zizyphus jujuba cv. Jiaxianmuzao could be an important dietary source of natural antioxidants for prevention of diseases caused by oxidative stress.