鸡蛋清中卵转铁蛋白的分离纯化

鸡蛋清经去卵粘蛋白、盐析后,获得卵转铁蛋白粗提物,通过两步Q-Sepharose Fast Flow离子交换色谱纯化卵转铁蛋白(OVT),利用SDS-PAGE电泳和HPLC法检测其纯度.结果表明,两步阴离子交换色谱获得纯度分别为78.26%和97.53%的卵转铁蛋白.     

鸡蛋清中卵转铁蛋白的分离纯化

鸡蛋清经去卵粘蛋白、盐析后,获得卵转铁蛋白粗提物,通过两步Q-Sepharose Fast Flow离子交换色谱纯化卵转铁蛋白（OVT）,利用SDS-PAGE电泳和HPLC法检测其纯度。结果表明,两步阴离子交换色谱获得纯度分别为78.26%和97.53%的卵转铁蛋白。      

鸡蛋清中卵转铁蛋白的分离提取

采用固定化金属螯合亲和色谱法(IMAC),从蛋清中分离和提取卵转铁蛋白(OVT).结果表明,采用均质处理蛋清液并结合硅藻土过滤澄清的预处理方法,去除了蛋清中的粘蛋白等一些影响柱分离的杂质蛋白,减轻了色谱柱的污染,延长了柱的使用寿命,从而降低了生产成本.SDS-PAGE电泳分析显示,分离提取的OVT纯度达到96%,远高于商品OVT;电喷雾质谱分析显示,OVT的相对分子质量为76 500.     

醇析法结合离子交换法提取分离卵转铁蛋白

乙醇析出法结合两步弱酸性阳离子交换层析可有效地从鸡蛋清中分离纯化卵转铁蛋白,结果表明:预处理后黏度降低的蛋清经两步醇析法(45%浓度乙醇沉淀杂蛋白、59%乙醇浓度沉淀获得OVT粗品),再经两步阳离子层析法(第一步:pH8.0,20 mmol/L磷酸盐缓冲液平衡,含0.5 mol/L NaCl的pH8.0,20 mmol/L磷酸盐缓冲液洗脱;第二步:pH5.2,10 mmol/L柠檬酸盐缓冲液平衡,含0.5 mol/L NaCl的pH5.2,10 mmol/L柠檬酸盐缓冲液洗脱)可得到纯度较高的卵转铁蛋白;SDS-PAGE电泳检测终产品的纯度大于96%。     

卵转铁蛋白的性质及应用

介绍了卵转铁蛋白的分子组成及其性质,从转铁功能、抑菌功能、调节功能、抑制自由基生成等方面阐述了卵转铁蛋白的生物学功能,例举了卵转铁蛋白作为食品添加剂、抑菌剂方面的应用。     

卵转铁蛋白体外免疫活性研究

研究卵转铁蛋白(OVT)的体外免疫活性。分别采用中性红吞噬法测定卵转铁蛋白对小鼠腹腔巨噬细胞吞噬功能的影响;MTT法测定卵转铁蛋白对小鼠腹腔巨噬和脾淋巴细胞增殖作用的影响;双抗体夹心ELISA法测定卵转铁蛋白对脾淋巴细胞IL-2分泌水平的影响。结果表明,OVT能显著增强小鼠腹腔巨噬细胞对中性红吞噬能力(P<0.01),协同LPS促进腹腔巨噬细胞的增殖(P<0.05),并显著改善由CsA引起的对小鼠腹腔巨噬细胞增殖活性的抑制作用(P<0.05);OVT能显著促进脾淋巴细胞的增殖(P<0.01),协同LPS和ConA促进小鼠脾淋巴细胞的增值(P<0.05),并能显著促进小鼠正常脾淋巴细胞IL-2的分泌(P<0.01)。在体外培养的条件下,卵转铁蛋白对正常小鼠免疫细胞的免疫能力有促进作用。     

一步层析法分离高纯度蛋清过敏原卵转铁蛋白

鸡蛋是引起食物过敏最常见的食物之一.为了快速高效分离鸡蛋中主要过敏原卵转铁蛋白,开展鸡蛋过敏的研究,采用DEAE-Sepharose Fast Flow阴离子交换层析一步分离出高纯度、高回收卒的卵转铁蛋白,纯度达97%,回收率为87.47%.本实验所建立的方法操作简便,设备简单,分离效率高,纯化出的卵转铁蛋白可为进一步研究提供实验材料.     

一步层析法分离高纯度蛋清过敏原卵转铁蛋白

鸡蛋是引起食物过敏最常见的食物之一。为了快速高效分离鸡蛋中主要过敏原卵转铁蛋白,开展鸡蛋过敏的研究,采用DEAE-Sepharose Fast Flow阴离子交换层析一步分离出高纯度、高回收率的卵转铁蛋白,纯度达97%,回收率为87.47%。本实验所建立的方法操作简便,设备简单,分离效率高,纯化出的卵转铁蛋白可为进一步研究提供实验材料。      

色谱法在鸡蛋清主要过敏原分离纯化中研究进展

鸡蛋营养丰富,同时也是引起人体过敏的主要食物之一。蛋清中含有4种主要过敏原,包括卵白蛋白、卵转铁蛋白、卵类黏蛋白和溶菌酶。概述了鸡蛋中4种主要过敏原的理化特性及色谱法纯化过敏原的研究进展,旨在为规模化分离得到高纯度和高活性的过敏原提供参考。     

一步法分离鸡蛋清中三种主要过敏原的研究

为快速高效分离鸡蛋中主要过敏原开展鸡蛋过敏的研究,本实验采用DEAE-Sepharose FF 色谱柱一步分离鸡蛋中的三种主要过敏原卵白蛋白、卵转铁蛋白和溶菌酶,通过SDS-PAGE 比对,纯度均高于相应标准品纯度,得率分别为87.66%、55.87% 和92.80%。本实验操作简便、设备简单、分离效率高,是一种分离鸡蛋过敏原的好方法。     

Functional properties of ovotransferrin from chicken egg white and its derived peptides: a review

Food Science and Biotechnology - With emerging trends in the food and pharmaceutical industries, potential applications of egg-derived bioactive compounds were recognized. Ovotransferrin is a major...     

Two-step chromatographic procedure for the preparation of hen egg white ovotransferrin

 A two-step chromatographic procedure for the preparation of hen egg white ovotransferrin by using an anion exchanger is described. The method consists of a preliminary step of frontal chromatography, also called displacement chromatography, on a Q Sepharose Fast Flow column. This simple and powerful chromatographic step enables the pre-purification of ovotransferrin that is further purified by a second conventional preparative chromatography performed on the same Q Sepharose FF column. The ovotransferrin obtained is found to be homogeneous in electrophoresis and analytical chromatography. Its purity rate is calculated at 97.5% and its amino acid composition is close to that obtained from the nucleotide sequence of ovotransferrin. Moreover, ovotransferrin is iron-free, thus suitable for studies in relation to its metal-binding activity. Received: 31 March 2000 / Revised version: 29 May 2000     

Oxygen radical absorbance capacity of peptides from egg white protein ovotransferrin and their interaction with phytochemicals

Egg proteins are important components for the development of functional foods and nutraceuticals. This study investigated the oxygen radical-scavenging effects of egg white protein ovotransferrin (including the whole protein, thermolysin–pepsin hydrolysate, and its bioactive peptides) and their interactions with four phytochemicals (vitamin C, epigallocatechin gallate (EGCG), caffeic acid, and quercetin), based on the oxygen radical absorbance capacity (ORAC) assay. The results showed that the hydrolysate possessed significantly higher oxygen radical absorbance capacity than the whole protein. The peptide IRW possessed very strong oxygen radical-scavenging effect, which might be attributed to its constitutive amino acid tryptophan (W) and the peptide bond between arginine (R) and W. Both the hydrolysate and the whole protein of ovotransferrin showed negative effects on four phytochemicals. However, the interactions between peptides/amino acids and the four phytochemicals are complex: some are positive, while others are negative. The results suggest that not only the phytochemicals, but also the hydrolysates or the peptides from the egg proteins could be a potential source of natural antioxidants.     

Ultrafiltration-modified chicken egg white lysozyme and its antibacterial action

The aim of the study was to produce a lysozyme preparation with an increased content of enzyme polymeric forms using the ultrafiltration (UF) technique. The effect of selected parameters of the membrane process on the extent of enzyme modification was examined. The study showed that the membrane technique, developed for the production of lysozyme monomer, could also be used in the direct production of a preparation containing enzyme polymers. Under optimal conditions of the modification procedure, the obtained preparation contained 53.3% of lysozyme polymeric forms. The effectiveness of the antibacterial action of UF-modified lysozyme against selected strains of bacteria was determined. Its bacteriostatic activity depended on the applied modification conditions. Among lysozyme preparations modified by UF, the highest bacteriostatic activity against selected strains of bacteria was recorded in the preparation containing 53.3% polymeric forms. The modification procedure facilitates the extension of the antibacterial spectrum of lysozyme against Gram-negative bacteria ( Pseudomonas fluorescens ) .     

Multifunctional peptides from egg white lysozyme

Hen’s egg white lysozyme (HEWL) is one of the major egg white proteins with well demonstrated antimicrobial activity. Bioactive peptides other than antimicrobial peptides from HEWL have not been reported; therefore, the purpose of the study was to explore new bioactivities of lysozyme-derived bioactive peptides. HEWL was hydrolysed with Alcalase and fractionated by cation-exchange chromatography. The Alcalase HEWL hydrolysate and its fractions were analyzed for inhibitory activities against calmodulin-dependent phosphodiesterase (CaMPDE) and antioxidant activities using oxygen radical absorbance capacity-fluorescein (ORAC-FL), 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical cation (ABTS⁺) and 2,2-di(4-tert-octylphenyl)-1-picrylhydrazyl (DPPH) radical scavenging methods. The fractionated peptides had higher CaMPDE inhibition activity, ORAC-FL value and ABTS⁺ scavenging activity than those of the hydrolysate. Peptide sequences in the most overall active fractions were characterized by LC–MS/MS. Our results showed that HEWL hydrolysate and its peptide fractions may serve as useful ingredients in the formulation of functional foods and nutraceuticals.     

Rapid growth of Salmonella enteritidis in egg white reconstituted from industrial egg white powder.

The aim of this study was to evaluate the consequences of the egg white-drying process on egg white ability to limit Salmonella Enteritidis growth in addition to the elucidation of the factors involved. We observed rapid growth of Salmonella Enteritidis inoculated in egg white reconstituted from industrial powder in comparison with that observed in liquid egg white collected in the laboratory: Salmonella cell counts rose from 10(3) to 10(8) cells/ml of egg white from powder during 24 h incubation at 30 degrees C. This rapid growth was observed in powder from all egg-breaking factories investigated, and it was comparable to that observed in optimum medium (tryptone soy broth). In view of the mechanism of egg white resistance and the major role played by iron availability and by ovotransferrin, we investigated several hypotheses to explain this rapid growth: iron provided during the drying process and/or denaturation of protein (especially ovotransferrin). The rapid growth observed in egg white reconstituted from powder was in relation to egg white protein denaturation and especially ovotransferrin denaturation during powder pasteurization that enhanced the availability of iron necessary for Salmonella growth. The major role played by ovotransferrin and iron deficiency on Salmonella growth in egg white was illustrated in this study.