Fractionation of Algerian common wheat proteins with 50 p.100 2-propanol: relationship with the technological quality

Sixteen Algerian common wheat genotypes have been analysed during three harvests for their technological and protein characteristics. Good relations have been found between alveograph W values and the strength parameters of the mixograph, although the mixograph parameters are less influenced by the crop year. Within the flour proteins extracted by 50 p.100 2-propanol, interesting and positive relations have been found between insoluble protein contents determined by the Kjeldahl method, insoluble proteins in total proteins ratios (0.5P2-INS/TP) and various strength parameters. Conversely, the soluble proteins in total protein ratios (0.5P2-S/TP) are negatively correlated with these parameters. These relations are globally confirmed by using an adapted Biuret method for protein dosage. Since 0.5P2-INS/TP or 0.5P2-S/TP ratios are not associated with TP content, they can constitute a good criterion to evaluate the intrinsic strength of common wheats in early selection. An original colorimetric method for insoluble glutenins (INS GLUT) dosage in 50 p.100 2-propanol is proposed and could be used to analyse the relations between the INS GLUT contents and the flour's technological quality.     

十二烷基硫酸钠-聚丙烯酰胺凝胶电泳法测定饮料中红豆含量

目的 建立十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE)法定量分析植物蛋白饮料中红豆成分含量的方法.方法 从8个主要蛋白条带中选取一个蛋白条带作为定量标记蛋白,配制红豆标准品进行SDS-PAGE实...     

聚丙烯酰胺凝胶电泳法快速检测植物源性食品中的蛋白成分

目的建立十二烷基磺酸钠-聚丙烯酰胺凝胶电泳法(sodium dodecyl sulfate polyacrylamide gel electrophoresis,SDS-PAGE)鉴定核桃、杏仁、花生、大豆中的蛋白成分,并分析植物蛋白饮料中蛋白质的来源。方法采用一步法植物活性蛋白质提取试剂盒分别提取预处理后的核桃、杏仁、花生、大豆等样品中的蛋白质成分,计算蛋白质的相对分子量,之后分别进行SDS-PAGE检测得到这几种蛋白成分的特征条带,并对不同样品中蛋白成分的电泳图谱进行比对。结果每一物种都有相对应的蛋白指纹图谱,不同种类的核桃含有相同的蛋白质亚基,具有高同源性,但核桃与花生、黄豆和杏仁含有不同种类大小的蛋白,具有高特异性。结论本方法快速、准确、灵敏,可有效分析植物蛋白饮料中各类蛋白质的来源,对食品中植物源性成分的鉴定具有重要意义。     

SDS-PAGE法检测动物肌肉蛋白质加热终点温度的研究

为了探索检测动物组织蛋白质热变性程度的方法,分别对猪、牛、羊、鸡、鱼五种新鲜动物肌肉组织进行不同温度的热处理（新鲜未加热、50、60、70、80、90、100℃）,对处理后的样品提取蛋白质进行十二烷基磺酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）分析。结果显示,同种动物组织经不同温度热处理,所得电泳图谱具有较大差异,电泳条带的数量随温度的升高逐渐减少,猪、牛、羊三种动物肌肉组织加热到80℃后,电泳图谱不再变化,达到加热终点温度;鸡和鱼的肌肉组织加热到70℃后,电泳图谱不再变化,达到加热终点温度。不同种动物组织经相同温度热处理所得电泳图谱显示：猪、牛、羊三种动物组织蛋白质的电泳图谱相似,与鸡和鱼组织蛋白质的电泳图谱差异显著。     

十二烷基硫酸钠-聚丙烯酰胺凝胶电泳技术及国内外蜂蜜掺伪检测技术研究进展

蜂蜜作为一种药食同源的食物,受到广大消费者的追捧。在利益的驱使下,市场上出现大量劣质蜂蜜,蜂产品质量良莠不齐,掺假现象严重损害了消费者权益。针对蜂蜜掺假手段的提高,现有标准无法满足检测的需求,如何分辨天然蜂蜜和假蜂蜜,成为监管部门和消费者兲心的共同话题。本文介绍了蜂蜜的概况,对国内外蜂蜜掺伪鉴别技术(碳同位素鉴定、高效液相色谱、中/近红外光谱)迚行概述,幵分析了各种方法的特点,重点介绍了十二烷基硫酸钠聚丙烯酰胺凝胶电泳检测方法的研究现状,以期在探索蜂蜜在蛋白质水平上的掺伪行为,规范蜂蜜市场健康发展的同时,为今后蜂蜜产品掺假鉴别技术的发展指明方向。     

Analysis of fish and squid myofibrillar proteins by capillary sodium dodecyl sulfate gel electrophoresis: actin and myosin quantification

 A capillary electrophoretic method for the separation and quantification of fish and squid myofibrillar proteins was developed. The method uses sodium dodecyl sulfate and β-mercaptoethanol for solubilization and analysis of myofibrillar protein subunits. The separation of the different polypeptides is achieved by the sieving effect of the gel inside the capillary. A calibration curve for myosin heavy chain and actin UV absorbance quantification of these proteins was developed. Received: 2 November 1999 / Revised version: 16 February 2000     

Fractionation by gel exclusion HPLC of proteins from acidic and alkaline extractions of Phaseolus beans

The proteins extracted from Phaseolus vulgaris (white kidney, navy) beans and P. lunatus (baby lima, large lima) beans by sodium hydroxide (NaOH) solution and citric acid (CA) solutions were fractionated by gel exclusion high-pressure liquid chromatography. The isoelectric amorphous proteins from the NaOH extraction and bipyramidal crystalline and spheroidal proteins from the CA extractions were also fractionated. Both the NaOH and the CA extracts of the beans contained 8–10 fractions. The proteins isolated from the extracts of the P. vulgaris beans were comprised predominantly of a relatively large molecular weight fraction, regardless of the microstructure of the protein precipitate; several of the fractions which were relatively major components of the extracts were not found in the precipitates obtained from the extracts. The differences in behaviour between the extracts and protein isolates of the different beans might be related to genetic variations.     

Cultivar identification of Vicia faba (L.) by sodium dodecyl sulphate–polyacrylamide gel electrophoresis of seed globulins

The globulin fraction isolation from Vicia faba seeds of different cultivars and different lines of the same cultivar has been examined by sodium dodecyl sulphate-poly-acrylamide gel electrophoresis (SDS-PAGE). The technique separates the globulin polypeptides into three distinct groups, termed A, B and C, with molecular weights above 46 kD, between 30–40 kD and below 26 kD, respectively. Distinct differences between polypeptide patterns of the different cultivars and of the different lines of the same cultivar were observed in groups A and B, little variation occurred in group C. Gradient zonal isoelectric precipitation was used to separate the globulin fraction of different cultivars into vicilin and legumin. Variation in polypeptide composition between cultivars was observed in both vicilin and legumin following SDS-PAGE. No difference between cultivars was detected in group C polypeptides of legumin.     

Characterisation of wheat flour and gluten proteins using buffers containing sodium dodecyl sulphate

The application of buffers containing the anionic detergent sodium dodecyl sulphate (SDS) to the study of wheat flour proteins is described. SDS-containing buffers are more effective than alternative solvents, including those which contain a cationic detergent, e.g. cetyltrimethylammonium bromide, in terms both of their ability to solubilise wheat proteins and of their suitability as buffers for column chromatography. Thus, a solvent containing 0.069m (2%) SDS solubilises a high proportion (95%) of flour protein, and gel filtration chromatography on columns of Sepharose CL-4B in the presence of 3.47 × 10^?3M (0.1%) SDS, particularly when used in conjunction with polyacrylamide gel electrophoresis, is a powerful tool for the detailed analysis of flour proteins. This technique enables flour proteins to be resolved into three major groups which have been identified as glutenins, gliadins and albumins plus globulins. It can be used to monitor increases in the molecular size of the glutenin fraction during the preparation of gluten from flour, and preliminary data suggests that there may be a correlation between the molecular size of this protein fraction and the breadmaking quality of the flour.     

The varietal identification of single seeds of wheat by sodium dodecyl-sulphate polyacrylamide gel electrophoresis of gliadin

Sodium dodecyl-sulphate polyacrylamide gel electrophoresis of gliadin is used to distinguish between wheat varieties which cannot be differentiated by starch gel electrophoresis. The technique identifies differences in high molecular weight gliadin polypeptides between the bread wheat varieties Sappo and Sicco, Flanders and Chalk, Cappelle Desprez and West Desprez and the three Durum varieties Durtal, Rikita and Lakota.     

Autolysis detection and evaluation of some lactic acid bacteria by renaturing sodium dodecyl sulphate‐polyacrylamide gel electrophoresis and polymerase chain reaction assays

Eleven lactic acid bacterial strains were tested for autolysis ability and the presence of autolytic enzymes by renaturing sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE). Polymerase chain reaction (PCR) assays for the detection of lysogenic strains were performed. Autolysis in a buffer system was observed in Lactobacillus delbrueckii subsp. bulgaricus DSM 20080, L. delbrueckii subsp. bulgaricus DSM 20081, Bifidobacterium longum subsp. infantis DSM 20088, B. angulatum DSM 20098 and Streptococcus thermophillus DSM 20617. Mitomycin C induction of prophage was demonstrated in B. longum subsp. infantis DSM 20088, B. angulatum DSM 20098, Lactobacillus acidophilus DSM 20242 and S. thermophillus DSM 20617. The presence of genes encoding known bacteriophage lysins was demonstrated by a PCR assay and correlated well with the autolytic phenotypes of the strains, indicating that PCR screening is useful in the rapid identification of autolytic strains.     

Solubilization of fish muscle proteins with buffers containing sodium dodecyl sulfate

The extraction of fish muscle protein using SDS containing solubilization buffers was studied varying the time and the temperature of solubilization, as well as pH and SDS concentration of the buffer. At pH less than 6 the myofibrillar proteins were incompletely solubilized; temperatures of 80-100 degrees C resulted in protein degradation observable in the SDS-PAGE. Samples of fish muscle containing high amounts of formaldehyde (50 mmoles FA/kg wet weight) could only be solubilised at 100 degrees C; on the other hand it was possible to solubilize cooked and/or canned products under mild conditions (2% SDS, 1% 2-ME, pH 8.9, shaking for 2 h at 60 degrees C).     

Solubilization of fish muscle proteins with buffers containing sodium dodecyl sulfate

Summary The extraction of fish muscle protein using SDS containing solubilization buffers was studied varying the time and the temperature of solubilization, as well as pH and SDS concentration of the buffer. At pH < 6 the myofbrillar proteins were incompletely solubilized; temperatures of 80-100 °C resulted in protein degradation observable in the SDS-PAGE.Samples of fish muscle containing high amounts of formaldehyde (50 mmoles FA/kg wet weight) could only be solubilised at 100 °C; on the other hand it was possible to solubilize cooked and/or canned products under mild conditions (2% SDS, 1% 2-ME, pH 8.9, shaking for 2 h at 60 °C).

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Solubilisierung von Fischmuskelproteinen durch Natriumdodecylsulfathaltige Puffer

Zusammenfassung Der Einfluß von Solubilisierungszeit und -temperatur, des pH-Wertes und der SDS-Konzentration des Solubilisierungspuffers auf die Extraktion von Fischmuskelproteinen wurde überprüft. Bei pH-Werten < 6 wurden die myofbrillären Proteine nur unvollständig gelöst; Solubilisierungstemperaturen von 80 bis 100 °C führten zu einem in der SDS-PAGE sichtbaren Proteinabbau. Fischmuskelproben mit hohem Formaldehydgehalt (50 mmole FA/kg Feuchtgewicht) ließen sich nur bei 100 °C vollständig solubilisieren; demgegenüber gelang die weitgehende Solubilisierung gegarter und/oder sterilisierter Produkte unter milden Bedingungen (2% SDS, 1% 2-ME, pH 8,9; 2stündiges Schütteln bei 60 °C).

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Abbreviations FA formaldehyde - IEF isoelectric focusing - 2-ME 2-mercaptoethanol - PA polyacrylamide - PAGE polyacrylamide gel electrophoresis - pI isoelectric point - SDS sodium dodecyl sulfate - TMAO trimethylamine oxide - Tris Tris (hydroxymethyl)methylamine     

Fast analysis of proteins in wines by capillary gel electrophoresis

Wine proteins play an important role in different characteristics of wine (e.g., aroma and body, foaming in sparkling wines). They can also cause a number of technological problems during vinification and may be responsible for the appearance of turbidity in bottled wine. These important features of proteins in wine have made necessary the development of new and fast analytical methods that can provide deeper knowledge about these biopolymers. However, separation and characterization of wine proteins is difficult and time-consuming mainly due to their low concentration and large number of interfering compounds. Besides, long sample preparation protocols can bring about protein decomposition. This paper proposes a new and fast method for carrying out the analysis of the protein fraction of wines. The procedure consists of direct treatment of wine using a centrifugal filter device (CFD), denaturation of the proteinaceous fraction with sodium dodecyl sulfate (SDS) and 2-mercaptoethanol, and subsequent CGE analysis of SDS-proteins. Results on the molecular weight (Mw) and relative quantity of proteins of wines are attained in about 1 h with this procedure. The method is applied to analyze different wines from Canary Islands. To our knowledge, this is the first report of separation of wine proteins according to their Mw by CGE.     

Quantification of monomeric and polymeric wheat proteins and the relationship of protein fractions to wheat quality

Wheat protein composition is important for understanding the biochemical basis of wheat quality. The objective of this study was to design a simple protein fractionation protocol with low cross‐contamination and to show that these protein fractions were associated with wheat quality. The protocol consists of three sequential extractions from 100 mg of flour with 7.5% propan‐1‐ol and 0.3 M sodium iodide (monomeric‐rich protein), 50% propan‐1‐ol (soluble glutenin‐rich protein) and 40% propan‐1‐ol and 0.2% dithiothreitol (insoluble glutenin‐rich protein). Nitrogen content of protein solubility groups was determined from dry residues using an automated combustion nitrogen analyser. About 90% of the total protein in the flour was solubilised. Cross‐contamination of protein fractions was evaluated by SDS‐PAGE, SE‐HPLC and RP‐HPLC. Variation in nitrogen content of the protein solubility fractions was lowest for monomeric‐rich protein (<2%) and insoluble glutenin‐rich protein (<4%). Three wheats with similar high‐molecular‐weight (HMW) glutenin subunit composition, Alpha 16, Glenlea and Roblin, varied significantly (P ≤ 0.05) in the proportion of monomeric‐rich and insoluble glutenin‐rich protein in the flour. Dough rheological properties were directly related to the proportion of insoluble glutenin‐rich protein and inversely related to the proportion of monomeric‐rich protein. The protocol was validated using an expanded set of 11 wheats which also showed that inter‐cultivar differences in the proportion of monomeric‐rich, insoluble glutenin‐rich protein and glutenin‐to‐gliadin ratio in the flour governed dough rheological properties such as mixograph, farinograph and microextension tests. The protocol has merit for quality screening in wheat‐breeding programmes when the sample size is too small or when time constraints limit the ability to perform traditional rheological tests. For the Department of Agriculture and Agri‐Food, Government of Canada, Copyright © Minister of Public Works and Government Services Canada 2003. Published for SCI by John Wiley & Sons, Ltd.     

SDS-Chitin-PAGE电泳法分析大葱叶几丁质酶特性

使用Sodium dodecyl sulfate-几丁质-聚丙烯胺酰胺凝胶电泳（SDS-Chitin-PAGE）方法分析了大葱葱叶几丁质酶的特性。在大葱叶组织中共检测到三种几丁质酶同工酶,分别命名为CH-A、CH-B、CH-C。分析结果表明,这三种几丁质酶具有SDS抗性,β-巯基乙醇对其活性也无显著影响。在SDS-Chitin-PAGE前,样品缓冲溶液与样品蛋白粗提液孵化处理的最适温度为24℃、时间为10～20min。凝胶电泳酶活分析表明,大葱葱叶中CH-A、CH-B的耐热温度可达60℃,CH-C的耐热温度达到70℃。葱叶中CH-A的最适pH为5.2～5.6,CH-B的最适pH为4.0～4.4,CH-C的最适pH为6.6～8.0。      

SDS-Chitin-PAGE电泳法分析大葱叶几丁质酶特性

使用Sodium dodecyl sulfate-几丁质-聚丙烯胺酰胺凝胶电泳(SDS-Chitin-PAGE)方法分析了大葱葱叶几丁质酶的特性.在大葱叶组织中共检测到三种几丁质酶同工酶,分别命名为CH-A、CH-B、CH-C.分析结果表明,这三种几丁质酶具有SDS抗性,β-巯基乙醇对其活性也无显著影响.在SDS-Chitin-PAGE前,样品缓冲溶液与样品蛋白粗提液孵化处理的最适温度为24℃、时间为10～20min.凝胶电泳酶活分析表明,大葱葱叶中CH-A、CH-B的耐热温度可达60℃,CH-C的耐热温度达到70℃.葱叶中CH-A的最适pH为5.2～5.6,CH-B的最适pH为4.0～4.4,CH-C的最适pH为6.6～8.0.