A new method for determination of antithrombotic activity of egg white protein hydrolysate by microplate reader

A new method for the determination of antithrombotic activity of egg white protein hydrolysate （EWPH） was developed using a microplate reader. Reaction was carried out at 37℃and pH 7.2 with fibrinogen concentration 0.1%. Microplate reading was conducted at 405 nm. Inhibition rate of EWPH on thrombin activity showed linearity （R2 = 0.9971）, when the inhibition rate was in the range of 10-90%. The lower limit of detection （LLD, at 99.7% probability） and the biological limit of detection （BLD, at 99.7% probability） of the method were 10.643 and 40 mg/mL, respectively. The repeatability standard deviation （R.S.D.） was 1.08%. The standard deviation of the method was ±0.027 AT-U.

Regulation of Microstructure of Calcium Carbonate Crystals by Egg White Protein

Crystal growth of calcium carbonate in biological simulation was investigated via egg white protein with different volume fractions,during which calcium carbonate was synthesized by calcium chloride and sodium carbonate.The morphology,thermal properties and microstructure of the calcium carbonate micro-to-nanoscale crystals were characterized by scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,Fourier transform infrared spectroscopy（FTIR）,thermogravimetric analysis（TG） and X-ray diffraction（XRD） analysis.The results show that the volume fraction of egg white protein has great influence on the shape,size and morphology of calcium carbonate crystals.The calcium carbonate crystals were the mixtures of calcite-vaterite-like crystals including spherical and rough surface,which are different from that formed in pure water.With the increase of egg white protein concentration,the diameter of calcium carbonate crystals changed,the amount of formed spherical calcium carbonate particles decreased and that of vaterite increased.These results indicate that the coordination and electrostatic interaction between egg white protein and Ca2＋ significantly affect the calcium carbonate crystalization.

Analysis on the Variation Expression of Difficult-Dissolved-Proteins of Diapause Eggs After Activating by Acid Treatment

Using HCl to activate the diapause eggs is a traditional technique of artificial hatching applied in silkworm egg production. Its mechanism has not yet been clarified. This experiment explored the effect of HCl on the termination of diapause of silkworm eggs cold-stored for 45 days from the point of proteomes. Two-dimensional electrophoresis techniques and ESI- MS-MS were used to compare and analyze the variation expression of difficult-dissolved-proteins of diapause eggs coldstored for 45 days before and after acid treatment. Through analysis on the two-dimensional electrophoretogram, there were 296 dots before acid treatment and 302 after the treatment, respectively. Amongst them 265 dots were matchable. The matchability reached 88.6%. There were 31 specific protein dots before acid treatment and 37 after acid treatment, respectively. ESI-MS-MS analysis was conducted for two specific protein-rich dots which disappeared after acid treatment. The results indicated that the sequence of No. 1 protein dot had 55 amino acids＇ peptide matched with those of chorion protein （Bombyx mori）. While the sequence of No. 2 protein dot had only 15 amino acids＇ peptide matched with those of heat shock protein hsp 19.9 （Bombyx mori）, and it was presumed to be an unknown protein. The difficult-dissolvedproteins of diapause eggs have variation expression after acid treatment. Some proteins before and after acid treatment are changed in MW.

Phase Transformation of Amorphous Calcium Carbonate to Single-Crystalline Aragonite with Macroscopic Layered Structure in the Presence of Egg White Protein and Zinc Ion

Highly oriented calcium carbonate lamellas are exquisite structure produced by biomineralization. Strategies mimicking nature have been developed to synthesize inorganic materials with excellent structures and optimal properties. In our strategy, egg white protein and zinc ion were employed in the solution to induce the crystallization of calcium carbonate, resulting in the macroscopic aragonite laminate with an average length of 1.5 mm, which was comprised of single-crystalline tablets. During the crystallization at initial stage, it was found that the particles displayed the characteristics of amorphous calcium carbonate, which was then transformed into the sophisticated structured aragonite through a multistage assembly process. The rebuilt nacre structure in vitro was achieved owing to the synergistic effects of egg white protein and zinc ion.

Extraction and identification of membrane proteins from black widow spider eggs

The eggs of oviparous animals are storehouses of maternal proteins required for embryonic development. Identification and molecular characterization of such proteins will provide much insight into the regulation of embryonic development. We previously analyzed soluble proteins in the eggs of the black widow spider （Latrodectus tredecimguttatus）, and report here on the extraction and mass spectrometric identification of the egg membrane proteins. Comparison of different lysis solutions indicated that the highest extraction of the membrane proteins was achieved with 3%-4% sodium laurate in 40 mmol/L Tris-HCI buffer containing 4% CHAPS and 2% DTT （pH 7.4）. SDS-PAGE combined with nLC- MS/MS identified 39 proteins with membranelocalization annotation, including those with structural, catalytic, and regulatory activities. Nearly half of the identified membrane proteins were metabolic enzymes involved in various cellular processes, particularly energy metabolism and biosynthesis, suggesting that relevant metabolic processes were active during the embryonic development of the eggs. Several identified cell membrane proteins were involved in the special structure formation and function of the egg cell membranes. The present proteomic analysis of the egg membrane proteins provides new insight into the molecular mechanisms of spider embryonic development.

The Effect of Varied Dietary Crude Protein Levels with Balanced Amino Acids on Performance and Egg Quality Characteristics of Layers at First Laying Phase

Four diets were formulated to study the influence of varying crude protein levels on the performance, egg quality, serum and haematological characteristics at the first phase of laying cycle of sixty Bovan Nera laying birds that were randomly allotted to dietary treatments. The four experimental diets had five replicates each and three birds per repli-cate. Diet 1 contained 14% crude protein (CP), while diet 2 contained 15% CP, diets 3 and 4 contained 16% and 17% CP respectively. The experimental birds were fed for 10 weeks and the data collected were statistically analysed. Apparent variations recorded for all the performance characteristics such as Egg number, Hen-day production, Feed Conversion Ratio (FCR) and weight gain were significantly different (p < 0.05). The best FCR value were recorded by birds fed 17% CP (3.45), while the highest weight gain mean value were also recorded by birds fed 17% CP value. Findings indicated a direct relationship between dietary crude protein values and performance.

6种平衡型复方氨基酸注射液合成人体蛋白质营养价值的研究

目的:通过对临床常用的6个品种平衡型复方氨基酸注射液(BCAA)18AA(250 mL:12.5 g)、18AA-I(250 mL:17.5 g)、18AA-II(250 mL:21.25 g)、18AA-IV(250 mL:8.7 g)、18AA-V(250 mL:8.06 g)、18AA-V-SF(250 mL:8.06 g)营养价值的研究,为医院药品遴选和临床合理选药提供参考。方法:依据全鸡蛋蛋白模式,对6个品种BCAA必需氨基酸(EAA)第一限制氨基酸化学评分(CS)值、总EAA综合质量(包括必需氨基酸指数、与标准蛋白的贴近度)2个方面评价其营养价值。结果:第一限制氨基酸CS值由高到低为:18AA-II>18AA>18AA-V=18AAV-SF>18AA-I=18AA-IV。总EAA综合质量:必需氨基酸指数由高到低为:18AA-II>18AA>18AA-I>18AA-IV>18AA-V=18AA-V-SF。与全鸡蛋蛋白的贴近度由高到低为:18AA-II=18AA=18AA-I>18AA-IV>18AA-V=18AA-VSF;最终,6个品种BCAA的营养价值由高到低:18AA-II>18AA>18AA-I>18AA-IV>18AA-V=18AA-V-SF。结论:6个品种BCAA中,18AA-II营养价值最高、相同液体量氨基酸含量最高,是肝肾功能正常病人的首选药物。

寄生虫虫卵悬液永久封制玻片标本制作方法探索

目的:探索寄生虫虫卵液永久玻片封制标本的最佳制作方法。方法:在现有研究的基础上,改良虫卵悬液保存配方,再结合不同封片方法制作虫卵玻片标本,保存1 a后,再对其制作效果对进行观察。结果:用体积分数为50%的鸡蛋清、40%的福尔马林、10%的甘油配制的蛋白甘油液保存虫卵,再进行石蜡圈+树胶双封片制作效果最佳。结论:经比较发现虫卵保存液中甘油的含量多少对于虫卵永久封制玻片标本效果的影响很大,其次封制方法对于虫卵液的长期保存也尤为重要。

饲粮代谢能和粗蛋白水平对产蛋后期双莲鸡生产性能、蛋品质和肝脏脂代谢的影响

试验旨在研究饲粮不同代谢能和粗蛋白水平对产蛋后期双莲鸡配套系生产性能、蛋品质、肝脏脂代谢的影响。试验选取240只健康、体重及产蛋率接近的40周龄双莲鸡产蛋母鸡,随机分为6组,每组4个重复,每个重复10只鸡。试验采取2×3双因素设计,代谢能(ME)设定为11.30和10.88 MJ/kg两个水平,粗蛋白(CP)设定为16.2%、15.2%和14.2%三个水平,预试期2周,正试期12周。结果显示:(1)粗蛋白水平对产蛋率、料蛋比、平均蛋重无显著影响(P>0.05),但11.30 MJ/kg代谢能水平可显著降低51~54周龄双莲鸡产蛋率和平均日产蛋量(P<0.05),并显著增加平均蛋重(P<0.05)。(2)饲粮代谢能和粗蛋白互作极显著影响46周龄鸡蛋蛋白高度和哈氏单位(P<0.01),并显著影响50周龄鸡蛋蛋黄颜色(P<0.05);10.88 MJ/kg代谢能水平54周龄鸡蛋哈氏单位、蛋黄比例显著高于11.30 MJ/kg代谢能水平(P<0.05),而46、54周龄鸡蛋蛋黄颜色和46、54周龄鸡蛋蛋壳厚度极显著低于11.30 MJ/kg代谢能水平(P<0.01),50周龄蛋壳厚度显著低于11.30 MJ/kg代谢能水平(P<0.05);16.2%粗蛋白水平46周龄鸡蛋哈氏单位显著高于14.2%粗蛋白水平(P<0.05),而54周龄鸡蛋蛋黄比例极显著低于15.2%和14.2%粗蛋白水平(P<0.01)。(3)10.88 MJ/kg代谢能水平双莲鸡血清、肝脏甘油三酯水平,肝脏相对重量和腹脂相对重量以及肝脏脂肪酸合成相关基因如SREBP-1c、ACACA、FAS、SCD1表达量均显著低于11.30 MJ/kg代谢能水平(P<0.01)。综合分析,本试验条件下双莲鸡配套系蛋鸡产蛋后期(42~54周龄)代谢能和粗蛋白水平分别以10.88 MJ/kg和16.2%为宜。

超高压协同TG酶改性蛋清蛋白热诱导凝胶机理

为提高蛋清蛋白凝胶性,本研究以蛋清蛋白(Egg white protein,EWP)为研究对象,通过分析质构、持水率、分子作用力、傅里叶红外色谱、圆二色谱、粒径、电位、巯基含量、表面疏水力及扫描电镜的变化,探究超高压处理(Ultra-high pressure,UHP)、谷氨酰胺转胺酶处理(Transglutaminase,TG)及超高压协同TG酶处理(Ultra-high pressure synergistic Transglutaminase,UTG)的蛋清蛋白热诱导凝胶机理及结构的变化。结果表明:UHP-EWP、TG-EWP、UTG-EWP的硬度、弹性和持水性均有所提高,疏水相互作用力是维持凝胶的主要作用力;UHP-EWP、TG-EWP、UTG-EWP的α-螺旋含量均不同程度下降、β-折叠含量均上升;UHP-EWP的平均粒径值下降、电位绝对值下降,TG-EWP、UTG-EWP的变化与之相反;UHP-EWP、TG-EWP、UTG-EWP的游离巯基含量上升、总巯基含量下降、表面疏水性升高;凝胶结构更加致密光滑,平整度提高。本研究为蛋清蛋白热诱导凝胶改性提供了理论基础及研究思路。

pH对蛋黄-海藻酸钠乳液冷凝胶理化性质的影响及其机制分析

乳液冷凝胶因其独特的结构和功能特性显示出巨大的优势和广阔的应用前景。以蛋黄蛋白质(egg yolk protein, EYP)和海藻酸钠(sodium alginate, SA)为基质,通过高速剪切均质机与含葵花籽油混合(油相∶水相为3∶7),形成O/W型EYP-SA乳液冷凝胶。通过改变EYP-SA的pH,分析其热稳定性、水分分布、流变、溶解度、表面疏水性、分子间作用力及二级结构,探究pH对EYP-SA乳液冷凝胶理化性质的影响及机制。结果表明,pH值对EYP-SA乳液冷凝胶的性质有显著影响,随着pH的升高,EYP-SA对水的结合能力增强,逐渐形成了均匀致密的网络结构,展现出良好的热稳定性;在频率扫描测试中,pH的提高降低了样品的G′与G″,EYP-SA弹性和刚性减弱。溶解度和表面疏水性呈显著性相关,原因可能是pH升高,静电排斥力增强导致蛋黄颗粒解聚,溶解度增加的同时蛋白质结构展开,使原本嵌在蛋白质分子内的疏水基团暴露在蛋白质分子表面,疏水相互作用和氢键是EYP-SA乳液冷凝胶形成的主要分子力。pH为9.0时EYP-SA乳液中液滴小且分散均匀,更有利于物质包埋。这些发现为EYP-SA乳液冷凝胶在食品凝胶递送体系中的应用提供了重要的理论依据。

减蛋综合征病毒抗体胶体金免疫层析试纸条的研制及初步应用

为建立快速检测减蛋综合征病毒(EDSV)抗体的方法,基于EDSV的Fiber蛋白,制备快速检测EDSV抗体的免疫层析试纸条,为养禽业提供针对病原微生物的感染预警及免疫评估。利用胶体金标记EDSV Fiber蛋白抗原为探针,将羊抗鸡IgG和抗Fiber蛋白的抗体包被到硝酸纤维膜上,分别作为质控线和检测线,对家禽EDSV抗体水平进行监测。结果表明,制备的EDSV免疫层析试纸条具有高度特异性,与其他家禽病毒抗体无交叉反应,仅与EDSV抗体反应,在试纸条上产生可见的检测线;并且制备的试纸条具有高度稳定性,在室温条件下可至少保存6个月。应用制备的检测EDSV抗体的免疫层析试纸条对从河南、安徽、山东等地养鸡场采集的576份鸡血清样本检测,与血凝抑制试验(HI)结果进行平行比较,二者的Kappa值为0.878,具有良好一致性。综上,制备的检测ESDV抗体的免疫层析试纸条具有高度的特异性、敏感性、稳定性和易操作性,对EDSV抗体的临床检测具有实际应用价值。

牛乳和鸡蛋中致敏原物质的检测

牛乳、鸡蛋及乳、蛋制品富含蛋白质、维生素和矿物质等,是人们饮食结构中的常见食物,在为人类提供丰富营养素的同时,也容易引起部分人群的过敏。针对目前过敏发生情况和过敏原检测技术的发展现状,该文简述了牛乳和鸡蛋中的主要过敏蛋白、酶等,并介绍了过敏原常见检测方法,比较各检测方法的优缺点,为牛乳和鸡蛋过敏原的检测提供理论依据和指导。

蛋清蛋白微粒基低脂沙拉酱流变学特征及品质优化

本实验以蛋清蛋白微粒(egg white protein microparticles,EWPM)为代脂基质,研究EWPM/黄原胶(xanthan gum,XG)共混质量分数、pH值、氯化钠含量、糖含量、均质条件等对超低脂沙拉酱产品流变学特性的影响规律。研究发现,XG对EWPM基超低脂沙拉酱具有显著的增稠效果,然而含量过高会导致低脂沙拉酱恢复性下降。基础调味组分对超低脂沙拉酱品质的影响存在较大差异,pH值和盐对体系黏度影响较大,糖添加量对黏度的影响相对较小。适度的胶体磨均质转速和均质时间可以减小产品的粒径,增加其内部均一性,显著提高产品的整体黏度。本实验以沙拉酱流变学行为调控为重点,为低脂沙拉酱的研究提供一个更加明确的工艺优化方向。

蛋清蛋白对低脂凝固型酸奶品质的影响

该研究以蛋清蛋白作为品质改良剂制备低脂凝固型酸奶,探究乳蛋白与蛋清蛋白比例、总蛋白质含量和蔗糖含量对凝固型酸奶pH、硬度、流变学特性、水分状态及感官品质的影响。蛋清蛋白添加比例的升高使得酸奶pH、硬度、储能模量、表观黏度和持水性增加。总蛋白质量分数2.5%时无法形成凝固酸奶,总蛋白质量分数为3.5%和4.5%的酸奶能良好凝固。添加蔗糖能够改善酸奶的感官品质,结果显示添加蔗糖质量分数为6%的酸奶具有最高的感官评分。相关性分析表明,酸奶质地与其储能模量、pH呈正相关,与持水能力呈负相关。这些结果表明,蛋清蛋白能够改善低脂凝固型酸奶的品质。

鸡蛋清蛋白质糖肽的结构鉴定

鸡蛋清中主要蛋白质均为糖蛋白,经胃肠消化后将在消化道内产生大量糖肽,这些糖肽的结构需要被鉴定和明确。本研究采用胰蛋白酶将鸡蛋清消化,然后从水解物中通过亲水相互作用层析富集N-糖肽、以Retain AX层析结合AminoLink树脂吸附富集O-糖肽,运用液相色谱-质谱联用技术对糖肽结构进行解析,并借助生物信息学分析探究蛋清糖蛋白对肠道的潜在作用。经质谱解析,共鉴定到来自于49种N-糖蛋白的1720个N-糖肽结构,以及来自29种O-糖蛋白的565个O-糖肽结构。其中,卵黏蛋白糖肽结构最为多样,共有490个N-糖肽结构和216个O-糖肽结构。京都基因与基因组百科全书通路富集分析发现,含唾液酸修饰的N-糖蛋白主要涉及白细胞介素-17信号通路和铁死亡,而含唾液酸修饰的O-糖蛋白主要涉及胆固醇代谢、维生素消化吸收、低氧诱导因子-1信号通路和肾素-血管紧张素系统。本研究系统解析了鸡蛋清蛋白质的糖肽结构,为后续探究蛋清糖肽对肠道的潜在作用提供了重要的结构信息。

蛋清蛋白和魔芋胶对鹰爪虾虾糜凝胶制品消化和酵解特性的影响

通过构建体外消化及酵解模型,探究蛋清蛋白(eggwhiteprotein,EWP)和魔芋胶(konjac glucomannan,KGM)对鹰爪虾SSG(shrimp surimi gel,SSG)制品消化和酵解特性的影响。结果表明:SSG-EWP组的蛋白质消化率随EWP含量的增加先升高后降低,EWP也能提高SSG消化过程多肽的含量,其中SSG-EWP4%的体外消化率最高;而KGM对SSG的蛋白质消化率和多肽的释放无显著影响(P>0.05)。EWP和KGM均可以提高SSG消化产物中必需氨基酸的含量。抗氧化结果表明,EWP可以提高SSG制品消化产物的Fe2+螯合能力,但会降低1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除能力,KGM可以同时提高消化产物的Fe2+螯合能力和DPPH自由基清除能力,从而增加消化产物的抗氧化活性。此外,微生物组学分析结果显示,EWP在维持肠道微生物多样性和调控有益菌方面发挥的积极作用优于KGM。蛋白相邻类的聚簇代谢结果表明,肠道微生物的代谢途径主要有24条,其中碳水化合物、氨基酸等物质的转运和代谢是主要的相关途径。本研究为制备高品质鹰爪虾虾糜制品提供了技术指导。

蛋清蛋白絮凝处理脱除玉米秸秆水解液中的木质素衍生物

为了提升玉米秸秆水解液(corn stalks hydrolysate,CSH)的可生化降解性,研究了蛋清蛋白(egg white protein,EWP)絮凝处理对CSH中木质素衍生物去除的影响,并与氯化铁、阳离子聚丙烯酰胺等常规絮凝剂的效果进行对比。结果表明,在初始CODCr浓度为40 g/L的CSH中使用EWP进行热絮凝处理(100℃下加热5 min),CSH中大分子木质素(以浊度计算)去除率达(76.87±3.00)%,显著优于氯化铁、阳离子聚丙烯酰胺的处理结果 (P <0.05)。同时,EWP热絮凝处理未造成糖、呋喃及弱酸等化合物明显损失。这是由于EWP通过疏水反应与木质素衍生物结合,进一步通过巯基-二硫键交联形成大分子化合物,促进了木质素衍生物从CSH中去除。

蛋黄蛋白的可控酶解及其产物的促成骨细胞增殖活性

脱脂蛋黄粉是蛋黄卵磷脂工业化提取时的产物之一,其蛋白质及营养价值高,具有较大的商业利用前景。该文采用胰酶酶解脱脂蛋黄粉,以钙离子螯合率为主要评价指标,通过单因素(时间、温度、pH值和酶添加量)试验和响应面优化实验确定最优酶解工艺。同时评估该酶解产物的促MC3T3-E1成骨细胞增殖活性,以期对脱脂蛋黄粉进行高值化利用。结果显示,胰酶酶解脱脂蛋黄粉的最优工艺为:酶解时间3 h,酶解温度55℃,酶解pH值10.0和酶添加量1%时,钙离子螯合率87.12%。在此酶解条件下制备的酶解产物能显著促进MC3T3-E1成骨细胞增殖,在酶解产物质量浓度为1.00mg/mL时,蛋黄蛋白酶解液的促细胞增殖效果更加明显,达到空白组细胞数量的1.20倍。上述结果表明,胰酶可以有效酶解脱脂蛋黄粉,其酶解产物具有高促成骨细胞增殖活性,为脱脂蛋黄粉高值化利用奠定基础。

蛋清蛋白/黄油复合凝胶的特性研究

以蛋清蛋白(egg white protein,EWP)和黄油为原料,按照不同比例(1∶1、1∶2、1∶3、1∶4、1∶5,质量比)进行复配,经热诱导制备EWP/黄油复合凝胶,并分析其质构特性、持水性、乳化性、乳化稳定性、流变特性、扫描电镜及激光共聚焦的变化规律。结果表明,质构特性中的硬度及胶黏性随着黄油添加量的增加而增加,而弹性及内聚性则在EWP/黄油为1∶3(质量比)时达到最高(P<0.05);复合凝胶的持水性随着黄油添加量的增加而增加,在1∶4及1∶5(质量比)时差异不显著(P>0.05);当二者质量比为1∶3时,乳化性及乳化稳定性显著高于其他组(P<0.05);流变结果显示当二者质量比为1∶3时,复合凝胶具有较大的储能模量(G′)及较低的损耗因子tanδ,说明此比例下的黄油提高了复合凝胶的黏弹性;扫描电镜结果表明二者质量比为1∶3时促使复合凝胶形成了更致密紧凑的网络结构,而未添加黄油的蛋清蛋白凝胶则呈现孔洞较大且大小不均匀的结构特征;激光共聚焦结果显示EWP/黄油1∶3(质量比)时网络结构相对均匀,且无析水无孔隙。综上所述,EWP和黄油的质量比为1∶3时可以改善蛋清蛋白的乳化特性及凝胶特性,为后续替代食品中部分乳化盐,以降低食品中钠含量,制备相关低钠食品提供了数据支撑。