明胶的构象组份随抽提次序变化的研究

运用改进的ＳＤＳ－ＰＡＧＥ法，对明胶中的不同构象的组份随抽提次序的变化进行定量的测定和。工作结果表明：比α分子量小的肽链组份可以分离出５个峰，以αｐ１－５表示，最小的αｐ５组份的分子量约３万，αｐ５组份含量在第３和第４道胶中消失。αｐ组份的分子量，随抽提次序增多而不断增大。β组含量随抽提次序增多时变化不大。（最后一道高温抽提除外）。α１与α２两个不同构象的比值α１／α２比值差别较大。β组份变化情况     

明胶分子量分布测定和表征的研究进展(二)

<正> 6.SDS—PAGE(十二烷基硫酸钠-聚丙烯 酰胺凝胶电泳)法 从1959年Raymond和1964年Davis用聚丙烯酰胺凝胶分离人血清蛋白成功后,聚丙烯酰胺凝胶电泳得到了广泛的发展,成为分离、分析蛋白质、核酸类生物     

Quality Control and Stability Studies with the Monoclonal Antibody,Trastuzumab: Application of 1D- vs. 2D-Gel Electrophoresis

Recombinant monoclonal antibodies (rmAbs) are medicinal products obtained by rDNA technology. Consequently, like other biopharmaceuticals, they require the extensive and rigorous characterization of the quality attributes, such as identity, structural integrity, purity and stability. The aim of this work was to study the suitability of gel electrophoresis for the assessment of charge heterogeneity, post-translational modifications and the stability of the therapeutic, recombinant monoclonal antibody, trastuzumab. One-dimensional, SDS-PAGE, under reducing and non-reducing conditions, and two-dimensional gel electrophoresis were used for the determination of molecular mass (Mr), the isoelectric point (pI), charge-related isoform patterns and the stability of trastuzumab, subjected to stressed degradation and long-term conditions. For the assessment of the influence of glycosylation in the charge heterogeneity pattern of trastuzumab, an enzymatic deglycosylation study has been performed using N-glycosidase F and sialidase, whereas carboxypeptidase B was used for the lysine truncation study. Experimental data documented that 1D and 2D gel electrophoresis represent fast and easy methods to evaluate the quality of biological medicinal products. Important stability parameters, such as the protein aggregation, can be assessed, as well.     

Cooking does not impair the impact of pulsed electric field on the protein digestion of venison (Cervus elaphus) during in vitro gastrointestinal digestion

The present study was conducted to elucidate whether cooking impairs the positive effect of pulsed electric field (PEF) on the digestibility of venison during in vitro gastrointestinal protein digestion. Previous studies have used fresh uncooked meat to demonstrate the effect of PEF on protein digestibility during gastrointestinal digestion neglecting the effect that cooking could induce during meat preparation process. PEF-treated samples (T₁, 10 kV, 90 Hz, 20 µs) were cooked (core temperature of 75 °C) and subjected to in vitro simulated gastrointestinal protein digestion along with non-treated controls. A 3% increase of in vitro protein digestibility was found in cooked PEF-treated venison (P < 0.05). A positive (P < 0.05) impact of PEF processing was observed on overall protein digestion as measured by soluble protein (%) and SDS-PAGE. PEF did not change (P > 0.05) the release of minerals from cooked venison during digestion. Cooking had no negative influence on the mechanism through which PEF operates in improving the protein digestibility of venison.     

预热变性程度对大豆蛋白凝胶性质的影响

以非还原SDS-PAGE表征大豆蛋白的预热变性程度,并采用质构分析、流变分析研究预热变性程度对大豆蛋白凝胶性质的影响。SDS-PAGE结果表明,随着加热温度的升高蛋白质变性速率逐渐增大,相同加热时间条件下,蛋白质变性程度随加热温度升高呈S型曲线上升。质构、流变分析结果表明:随着预热变性程度的增大,大豆蛋白凝胶硬度先增大后减小,变性程度为86.11%时凝胶硬度最大,是未经预热变性的大豆蛋白凝胶硬度的2.15倍;凝胶弹性则随预热变性程度的增大持续增大;变性程度在22.28%以上时大豆蛋白形成凝胶更快,但完全变性大豆蛋白在形成凝胶时的降温阶段不能形成很好的凝胶结构。粒径分析结果表明,预热变性程度对大豆蛋白凝胶性质的影响与蛋白质预热变性时形成的聚集体尺寸及形态有关。     

Electrophoretic and HPLC methods for comparative study of the protein fractions of malts,worts and beers produced from Scarlett and Prestige barley (Hordeum vulgare L.) varieties

Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and reversed-phase high performance liquid chromatography (RP-HPLC) methods were used for studying the protein fractions (hordeins; albumins and other soluble proteins) of Scarlett and Prestige barley malts and to follow changes of the protein profile of worts and beers from these two malt varieties. Similar industrial brewing conditions were applied for both varieties.     

不同电解质溶液对反胶束萃取花生蛋白的影响研究

研究了KCl、NaCl、LiCl、MgCl2、NaNO3、KNO3、Na2SO4、MgSO4 8种不同的电解质对AOT/正己烷反胶束溶液萃取低温花生粕中花生蛋白的影响,对反胶束的含水量、蛋白质的提取率及通过SDS-PAGE电泳试验对蛋白质的亚基条带进行了比较。试验结果表明,电解质的种类会影响反胶束的含水量;阴离子与阳离子对反胶束溶液萃取大豆蛋白的前萃与后萃都有影响,电解质KCl和NaCl溶液所提取的蛋白质得率较高,分别为54.22%和50.19%;不同的电解质可以影响所得蛋白的亚基组成,可以用来分离不同的蛋白。     

聚乙二醇/硫酸铵双水相萃取猪胃蛋白酶工艺研究

采用聚乙二醇/硫酸铵[PEG/(NH4)2SO4]建立稳定的双水相体系以分离猪胃蛋白酶。通过上下相体积比(VR)、比活力(SA)、纯化因子(PF)、酶活回收率(η)和SDS-聚丙烯酰胺凝胶电泳(SDS-PAGE)分析测定萃取效果。结果表明,萃取猪胃蛋白酶的最佳配比体系为25%PEG1000:18%(NH4)2SO4,所萃取的猪胃蛋白酶酶活回收率为91.5%,SDS-PAGE结果显示,萃取的蛋白质和猪胃蛋白酶对照品分子量大小一致。     

20种蚕豆样品蛋白质含量与其蛋白组分的分子质量

采用微量凯氏定氮、蛋白质分级提取、变性凝胶电泳（SDS-PAGE）等技术研究了我国蚕豆主产区20种代表性蚕豆样品的蛋白质含量,蚕豆蛋白质中水溶性、盐溶性以及醇溶蛋白质的质量分数,以及蚕豆水溶性与盐溶性蛋白质亚基的分子量分布。结果表明：中国蚕豆主产区20种蚕豆样品的蛋白含量范围26.48～32.51g/100g,20种蚕豆蛋白含量差异显著（p<0.05）。20种蚕豆样品中的水溶性蛋白、盐溶性蛋白、醇溶蛋白的含量分别为88.6%～92.4%、4.3%～7.5%、 0.3%～2.5%、其他非蛋白氮为0.3%～2.5%。不同品种间的蚕豆水溶性、盐溶性蛋白亚基组成具有一定的差异;SDS-PAGE电泳分析,蚕豆水溶性蛋白共分离出10～19条迁移率不同的条带, 亚基分子量集中在43.0～95.0ku之间, 盐溶性蛋白共分离出7～16条不同迁移率的条带,因品种不同而不同。分子质量为65、55、48、43、32ku的谱带在20种蚕豆盐溶蛋白中均检测出来,为共有带。     

Genetic Variation in Glutenin Protein Composition of Aestivum and Durum Wheat Cultivars and Its Relationship with Dough Quality

Genetic variability of high molecular weight glutenin subunits and low molecular weight glutenin subunits composition at the Glu-1 loci in Triticum aestivum L., and T. durum L., wheat was studied using sodium dodecyl sulfate polyacrylamide gel electrophoresis and polymerase chain reaction based markers. The end use quality of wheat is mainly influenced by the composition of glutenin protein. Aestivum cultivar GW-273 showed highest gluten index (94.4%) and sedimentation value (61 mL). GW-273 and GW-322 showed highest Glu-1 score of 10 out of 10, indicating superior dough quality for bread making. Results from glutenin protein separation using electrophoresis revealed that selected Indian wheat cultivars were abundant in high molecular weight glutenin subunits AxNull allele, which is responsible for poor quality. Gene specific polymerase chain reaction using high molecular weight glutenin subunits and low molecular weight glutenin subunits primers showed Dx5 and Dy10 in only two cultivars GW-273 and GW-322, which is responsible for good dough quality. Sequencing of high molecular weight glutenin subunits Dx5 gene fragment showed four cysteine at the N-terminal end. Cysteine residues are helpful in intermolecular disulfide bond formation among different glutenin and gliadins proteins leading to good elasticity of dough.