α-淀粉酶法制备小麦胚芽蛋白的研究

小麦胚芽用超临界CO2脱脂,用α-淀粉酶水解麦胚蛋白提取液中的淀粉,酸沉淀麦胚蛋白,使麦胚蛋白含量和得率均较碱溶酸沉淀法明显提高,分别达到94.5%和81.36%,用高效毛细管电泳鉴定小麦胚芽蛋白的纯度,SDS-PAGE电泳测定小麦胚芽蛋白的分子量。     

IgY isolation from a watery by-product obtained from an egg yolk fractionation process

The possibility of recovering IgY from a watery by-product produced during an egg yolk fractionation process was evaluated. The protocol employed for the extraction of IgY was the polyethylene glycol precipitation method. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) was carried out to confirm the presence of IgY at the different steps of the IgY purification process. Finally, the amount of IgY obtained was quantified by means of anion exchange chromatography. Native egg yolk was employed as IgY reference source, and results showed that the by-product could be at least as suitable as egg yolk as an IgY source. Additionally, the use of the by-product as a source of biotechnological compounds, such as IgY, leads to an increase in the value added during the egg yolk fractionation process.     

谷氨酰胺转胺酶对酪蛋白的改性效应

羊乳中的酪蛋白经商品级谷氨酰胺转胺酶作用后,产物经SDS-PAGE检测,发现生成了相对分子量较大的聚合物。聚合的最佳条件为:酶量/酪蛋白=15U/g;最适pH:6.0～8.0;最适反应温度:50℃;反应时间:120min。其中β-酪蛋白最易被催化,其次为αs-1酷蛋白,αs-2酷蛋白,k-酪蛋类白不易被催化。经谷氨酰胺转胺酶改性后的酪蛋白溶液,其粘度增加,乳化能力提高,起泡性下降。     

嗜酸乳杆菌亚油酸异构酶的分离纯化研究

本实验对嗜酸乳杆菌亚油酸异构酶的分离纯化进行了研究。嗜酸乳杆菌的粗酶液经40%～80%饱和度的硫酸铵盐析、透析、SephadexG-100凝胶过滤层析等步骤进行分离纯化后,酶的纯化倍数达到3.10,比活力为475.75U/(mg蛋白质);纯化后的亚油酸异构酶在SDS-PAGE电泳中只呈现一条带,并测得分子量约为46.6kDa。     

不同反胶束体系提取大豆蛋白质的研究

反胶束技术是一种新的生物技术,是表面活性剂在非极性溶剂中形成的与正胶束结构相反的含水聚集体。本文对四种常用表面活性剂所形成的反胶束在提取大豆蛋白质方面进行了研究,首次对它们“水池”（ω0）大小、蛋白质提取率及通过SDS-PAGE电泳实验对蛋白质的亚基条带进行了比较。     

SDS-PAGE of salted anchovies (Engraulis encrasicholus L) during the ripening process

 Changes in the muscle proteins during the ripening of salted anchovies have been examined using sodium dodecyl sulphate polyacrylamide gel electrophoresis. The chemical changes occurring in the muscle proteins of anchovy during the ripening process were related to the degradation of the myofibrillar structure of the muscle. In spite of a considerable protein degradation the ripened salted anchovy maintained its structure and was easily cut into fillets. Hydrolysis of muscle proteins was significant during the first 6 weeks. Proteins of molecular weight higher than 35 kDa were more likely to be hydrolysed. Myosin heavy chains were the most sensitive myofibrillar protein. α-Actinin, actin and tropomyosin were more resistant to enzymatic degradation. Due to protein build-up of peptides resulting from the breakdown of the higher molecular proteins, it was difficult to measure changes in the myosin light chains and troponin sub-units. Received: 28 December 1999 / Revised version: 9 March 2000     

Sesame seed as an alternative plant protein source: A comprehensive physicochemical characterisation study for alkaline,salt and enzyme-assisted extracted samples

Sesame seed is mostly utilised for its oil but also the waste of the oil processing; the seed meal has also significant potential to be used as an alternative protein source. In this study, the goal is to produce sesame seed protein by using three different techniques; alkaline, salt and enzyme-assisted extraction. A comprehensive physicochemical characterisation of the extracts was performed. Total and soluble protein contents, emulsification activity & emulsion stability, FTIR spectroscopy, hydration behaviour and gelling ability experiments by TD-NMR were conducted for all extracted proteins. Also, SDS-PAGE experiments were performed to observe the effect of extraction conditions on protein folding. Overall, the aqueous phase of enzyme-assisted extracted proteins (E-ACP) had the highest protein content and solubility, which resulted in other improved physicochemical properties. Salt extracted samples were ‘salted-out’, therefore, had poor physicochemical properties. TD-NMR experiments further confirmed the solubility and gelling ability results by measuring the change in the T₂ spin relaxation times. Additionally, FTIR spectroscopy confirmed the most critical peaks for the proteins; Amide I (C=O stretching) and Amide II (N–H bending). In summary, depending on the physicochemical property of interest, different extraction methods yielded proteins with different properties.     

Purification and characterization of superoxide dismutase from garlic

An efficient and easily scaled up method to isolate superoxide dismutase from garlic is proposed. The separation and purification procedure consists of phosphate buffer extraction, heat treatment and a two-stage ultrafiltration process. The enzyme was purified 139-fold with a specific activity of 2867 U/mg protein and a yield of 91%. The native molecular mass of superoxide dismutase estimated by fast protein liquid chromatography on a Superose 6 column was 28 kDa. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed a single band near 14 kDa, suggesting that native enzyme was homo-dimeric. The optimal pH for enzyme activity was found to be 7.0, and at this pH the enzyme exhibited maximum activity at 50 °C in 50 mM sodium phosphate buffer. Among various metal ions examined, Cu²⁺ and Zn²⁺ exerted a positive effect on superoxide dismutase activity, whereas Hg²⁺ was found to be a strong inhibitor. The final purified enzyme had an isoelectric point of 5.1-5.4 and a sheet content of 46%, consistent with the literature values. This shows that the purified SOD folded with a reasonable secondary structure.     

大豆脂肪氧化酶凝胶电泳分析研究

本文介绍利用SDS电泳、簿层等电聚焦电泳技术及激光光密度计扫描分析大豆脂肪氧化酶的方法,其中薄层等电聚焦电泳技术具有准确、快速、分辨率高的特点,并应用于53份大豆资源LOX同功酶缺失体的鉴定以及激光扫描定量测定酶带峰值面积,为在我国开展大豆脂肪氧化酶研究提供了鉴定技术。     

Japanese barnyard millet (Echinochloa frumentacea): Protein content,quality and SDS–PAGE of protein fractions

Total protein from five varieties of Japanese barnyard millet (Echinochloa frumentacea,) was separated into albumin/globulin, prolamin and glutelin fractions. The protein fractions were examined by sodium dodecylsulphate polyacrylamide gel electrophoresis. Total protein of the varieties ranged from 110·5 to 139·3 mg g^?1 of which 11·3–17·2% was albumin/globulins, 6·8–9·3% prolamins, 7·5–11·6% prolamin–like, 5·9–9·1% glutelin-like and 39·3–54·4% true glutelins. Amino acid analyses of the total protein showed that the varieties had essentially the same ammo acid composition. With the exception of lysine the amino acid levels adequately matched the provisional FAO scoring pattern. The amino acid composition of the protein fractions was also very similar. Electrophoretic analysis showed that the albumin/globulin fraction contained three or four components; the prolamin and glutelin fractions each had five components. The glutelin fraction had higher molecular weight components than the other two fractions.