两种不同功能蜘蛛丝的物理化学结构表征与力学性能

蜘蛛丝是一种具有优良机械性能的天然动物蛋白纤维,它特有的结构和性能与其生物学功能密切相关.采用氨基酸自动分析仪、傅立叶转换红外光谱仪、单纤强力仪和电子显微镜对棒络新妇(Nephila clavata)卵袋框丝(纺自大壶状腺)与内层丝(纺自柱状腺)两种不同功能蜘蛛丝的物理化学结构表征、力学行为与性能进行测试研究.结果表明这两种蜘蛛丝的氨基酸组成和蛋白二级结构与其力学行为与性能相一致,蜘蛛丝似乎呈现出一定的机械性能,以适应其不同的功能要求,这对人们进行新型安全防护材料的仿生设计将有重要的指导意义.     

高效液相色谱-原子荧光光谱联用技术测定富硒鸡蛋中的硒形态

为监测市场上富硒鸡蛋中蛋清及蛋黄中硒形态的种类及分布规律,优化建立了一种高效液相色谱-氢化物发生-原子荧光光谱联用技术测定富硒鸡蛋蛋清及蛋黄粉中硒形态的方法。随机选取富硒鸡蛋样品,进行蛋清蛋黄分离、冷冻干燥及蛋黄脱脂处理,处理后样品经Tris-HCl缓冲液（5 mmol/L, pH=7.5）55 oC恒温振荡、酶解提取,高速离心机（10000 r/min）离心10 min,上清液过0.22 μm有机滤膜后采用高效液相色谱-氢化物发生-原子荧光光谱联用技术进行测定,外标法定量。结果表明,该方法能在11 分钟内实现5种硒形态的基线分离,且各种硒形态的线性相关系数(r)均大于0.9994,其检出限在0.5-3.0 μg/L之间,回收率在81.6%~110.4%之间,可以满足检测需求,按照该实验方法测定市场上富硒鸡蛋中的硒形态,方法灵敏度高、准确性好,且测得的富硒鸡蛋蛋清样品中硒形态主要成分为硒代蛋氨酸,而蛋黄样品主要成分为硒代半胱氨酸,还有少量的硒代蛋氨酸,同时,一些鸡蛋还含有极少量的亚硒酸根,但蛋清及蛋黄中硒代氨基酸的含量总和占总硒含量的83.3-98.4%,适用于富硒鸡蛋中的硒形态提取。由此可见,市场上富硒鸡蛋中的硒主要以硒代氨基酸的形式存在,比较适合日常补硒,且该方法可以对市场上富硒食品起到一定监测作用。     

高效液相色谱法研究氨基酸测定中鸡蛋样品的微波水解

利用Pico-Tag高效液相色谱法（HPLC）研究了氨基酸分析中一种新的水解方法——微波水解法,鸡蛋样品以内含1％苯酚的6mol／L盐酸作为水解液水解,仅需7min即可求解完全,平均回收率为95％,相对标准偏差小于2％。方法简便、快速、准确、重现性好,适用于不同样品的水解处理。     

波动温度对乌龟卵孵化期和幼体表型特征的影响

在28℃、（28±3）℃和（28±6）℃温度条件下孵化乌龟（Chinemys reevesii）卵,检测上述温度条件对孵化期、孵化成功率、幼体大小以及运动能力的影响．孵化温度显著影响乌龟卵的孵化期、幼体重量和背甲大小,但对孵化成功率和幼体运动能力无显著影响．恒温条件下卵的孵化期短于波动温度,恒温条件下孵出的幼体体重大于波动温度条件下的幼体．因此,与恒温相比,波动孵化温度并不提高乌龟幼体质量．     

聚合物整体柱微萃取-高效液相色谱法检测鸡蛋中的磺胺嘧啶和磺胺二甲嘧啶残留

建立了鸡蛋中磺胺嘧啶和磺胺二甲嘧啶残留量的聚合物整体柱微萃取和高效液相色谱检测方法。以聚(甲基丙烯酸-乙二醇二甲基丙烯酸酯)毛细管整体柱作为萃取装置。为了得到较高的萃取效率,优化了影响萃取效率的参数(萃取流速、萃取体积、样品基质pH值)。样品经过匀浆、乙醇提取、磷酸盐缓冲溶液稀释、离心等步骤后直接进行萃取。鸡蛋中磺胺嘧啶和磺胺二甲嘧啶的检出限分别为11.2 ng/g和8.8 ng/g,在50～5000 ng/g的浓度范围内具有良好的线性关系。加标回收率大于65%,日内、日间测定的相对标准偏差不高于8.2%。结果表明,方法简单、快速、灵敏度高,适用于鸡蛋中磺胺嘧啶和磺胺二甲嘧啶的常规分析。     

Comparative Biochemistry of the Physiologically Active Components of Venom, Hemolymph, and Eggs of the Karakurt Spider (Latrodectus tredecimguttatus)

The physicochemical and functional properties of the venom, hemolymph, and egg extract of the karakurt spiderLatrodectus tredecimguttatuswere studied. A highly purified toxin that differs from the neurotoxins found previously in the venom was isolated from the hemolymph and characterized.     

The dynamics of the calcium‐induced chain–chain association in the polyuronate systems

The calcium‐induced formation of strong, hydrophilic gels is the important feature of polyuronates, connected with most of their practical applications. The insight into the molecular details of gelling process dynamics is hardly feasible for both experimental and theoretical methods. Here, the application of the transition path sampling method for studying this problem is reported; the focus was on the poly(α‐L ‐guluronate) systems, treated as the representative for all polyuronate‐containing systems. The results allowed for identifying several distinct local minima of the free energy lying on the transition paths and visited by the system during the process of chain–chain association. These minima usually correspond to the intermediate structures in which the water molecules bridge calcium ion and carboxyl groups. This work emphasizes the importance of water and provides more complete understanding of the calcium binding by the polyuronate chains. © 2012 Wiley Periodicals, Inc.     

Improvement of quality and flavor of salted egg yolks by ultrasonic assisted cooking

Physicochemical, texture indexes, microstructure and volatiles were used to characterize the changes in quality, structure and flavor of cooked salted egg yolks (SEYs) with or without ultrasonic treatment. Experimental results indicated that ultrasonic significantly increased cooking (water) loss, oil exudation, lipids oxidation (TBARS), accelerated the doneness of cooked SEYs and then promoted the generation of volatiles. These results were further confirmed by the improvement of thermal stability, the changes in color, secondary structure of proteins, water distribution and mobility. Meanwhile, more “fragments” and “cracks” were observed in scanning electron microscope (SEM) and the decrease in gumminess and chewiness were detected using texture profile analysis (TPA), inducing that the migration of lipids and collapse of gel network were intensified. Moreover, ultrasonic treatment decreased the content of sodium chloride in SEYs. Therefore, it was concluded that the doneness, quality and flavor of cooked SEYs were improved by ultrasonic treatment, which could be used as an effective and alternative method for the production of SEYs with good flavor, sandy and oily texture.     

Fast separation of hen egg white protein with a phosphorylcholine type zwitterionic ion chromatography stationary phase

In this work,a kind of preparation method of zwitterionic ion chromatography(ZIC) stationary phase modified with phosphorylcholine(PC) was obtained by hydrolyzing after bonding phosphorylcholine dichloride to diol-silica to better explore the characteristics of the PC groups as ZIC stationary phase ligand in simultaneous separation of acidic proteins and basic proteins. The results showed that tw’o kinds of acidic proteins and three kinds of basic proteins can be separated completely,meanwhile,hen egg white was separated and purified and three kinds of egg white components ovalbumin,G2 ovoglobulin and ovotransfemin proteins were separated completely by one single step on PC-ZIC column,the purity of all proteins reached above 95%.PC-ZIC stationary phase was successfully improved with better separation capacity and selectivity than previously reported in this paper.     

Preparation,Characterization and Optimization of Egg Albumin Nanoparticles as Low Molecular‐Weight Drug Delivery Vehicle

Protein nanoparticles have been recognized as carriers to deliver low molecular‐weight drugs, anticancer drug, DNA, vaccines, oligonucleotides, peptides and etc. The purpose of this research was preparation of Egg Albumin (EA) nanoparticle with suitable size/size distribution and good surface properties for drug delivery application based on simple coacervation method along with optimization of the nanoparticles by employing Taguchi method. Several synthesis parameters were examined to characterize their impacts on nanoparticle size and topography. These variables were including temperature, EA concentration, desolvating agent volume, pH value and agitation speed. In addition, size and morphology of prepared nanoparticles were analyzed by photon correlation spectroscopy (PCS) as well as atomic force microscopy (AFM). As result of Taguchi analysis in this research, desolvating agent volume and pH were most influencing factors on particle size. The minimum size of nanoparticles (～51 nm) were obtained at Temperature 55 °C, 30 mg/ml EA concentration, desolvating agent volume 50 ml, agitation speed of 500 rpm and pH 4. The mechanistic of optimum conditions for preparing protein nanoparticles from Egg Albumin for the first time and their characterization as delivering nano system are discussed.