脉冲毛细管电泳分离蛋白质的研究

蛋白质是机体细胞的重要组成成分,通过分析蛋白质可获得机体的受损或病变情况,因此毛细管电泳（CE）分析蛋白质分子在临床医学中具有重要的应用价值。该文以溶菌酶、生长激素、碳酸酐酶、肌动蛋白、牛血清白蛋白和磷酸化酶B为样本,采用有效长度为6 cm和总长度为8 cm的毛细管,以羟乙基纤维素（HEC）为分离介质,首次采用脉冲电场毛细管电泳（PFCE）,研究了脉冲频率及调制深度对不同蛋白质（分子量14.4～97.4 kDa）分离效率的影响。结果表明,相对于电场强度为100 V/cm的直流电场毛细管电泳（DCCE）,在1.4% HEC筛分介质中采用平均电场强度为100 V/cm,脉冲频率为10 Hz,调制深度为250%的脉冲电场时,相同蛋白质分子的分离时间缩短6.6%～9.6%;脉冲电场与蛋白质分子的共振频率为10 Hz,当脉冲频率低于共振频率时,分离时间随脉冲频率的增高而延长,反之则随脉冲频率的增高而减少;当脉冲频率与共振频率相同时,其分离度提高34.1%～88.1%,理论塔板数最高为4.03 × 104;在相同平均电场下,当调制深度由0提至250%时,筛分介质内的焦耳热比直流电场时提高了2.64倍;焦耳热的提高使得筛分介质的粘度降低,导致蛋白质分子在筛分介质内的迁移时间随电场脉冲调制深度的增加而减少,且蛋白质的分子量越大,其迁移时间越小,其中磷酸化酶B的迁移时间减少约9.6%,但相邻蛋白质分子间的分离度无明显降低。该研究为提高CE对蛋白质分子的分离效率提供了新方法。     

羟乙基纤维素中毛细管电泳DNA分离特性研究

本实验以羟乙基纤维素(HEC)为筛分介质,以100～1500 bp DNA ladder为分离对象,系统地研究了直流电场下毛细管电泳时DNA分离特性.论文考察了DNA迁移淌度及分离度随HEC溶液浓度和分子量、毛细管两端电场强度(E)、毛细管有效长度(le)及其内径形状、背景电解液(BGE)温度等因素变化规律.研究发现:(1)当筛分介质HEC浓度高于其阈值浓度c*时,HEC分子量越大,相邻DNA片段之间淌度差越大,HEC浓度越高,其迁移淌度越低;(2)对于相邻的DNA片段,le在一定范围内,其分离度随le增大而线性升高;(3)毛细管有效长度一定时,DNA淌度随毛细管侧面积与截面积之比R增大而升高,分离效率提高;(4)BGE温度升高,DNA在筛分介质中扩散效应增强,迁移淌度变大,相邻DNA片段间分离度减小.根据以上结论,在直流电场下毛细管电泳φ×174-Hirc II限制性酶切片段,并实现了其高分离度、快速分离.     

毛细管电泳-激光诱导荧光检测分枝杆菌脱氧核糖核酸限制性内切酶谱

建立了毛细管电泳分离-激光诱导荧光检测（CE-LIFD）分析分枝杆菌脱氧核糖核酸（DNA）限制性内切酶谱的新方法。用聚合酶链反应(PCR)扩增分枝杆菌hsp65基因的长度为439 bp的片段,该扩增片段经限制性内切酶BstEⅡ和 HaeⅢ酶切后,分别用CE-LIFD装置和常规琼脂糖电泳（AGE）对比检测酶切片段。对PCR扩增片段的酶切样品的预处理和CE条件进行了优化,获得了8种分枝杆菌DNA的限制性内切酶谱图。 DNA片段相对迁移时间的相对标准偏差（RSD）≤3.6%。结果表明,CE的分离效能明显高于AGE,是研究DNA限制性内切酶谱的更有效的检测手段。     

含有金纳米粒子的筛分介质对不同长度DNA片段的毛细管电泳分离

探讨了含有金纳米粒子(GNPs)的筛分介质在毛细管电泳(CE)中对不同长度DNA片段的分离.以聚环氧乙烷(PEO)-金纳米粒子(GNPs)-TBE为CE筛分介质,用涂层的毛细管柱(37 cm×75 μm,有效长度27 cm)分离DNA Marker D和1 kbp DNA Ladder Marker标准DNA片段,考察了CE过程中各参数(如筛分介质质量浓度、分离电压、温度和筛分介质pH值)对不同长度DNA片段分离的影响.对比了新型筛分介质与不含GNPs的PEO-TBE筛分介质的分离效果,并将新型筛分介质用于实际样品的检测.结果表明,在筛分介质中添加GNPs后能够改进CE的分离效果,且分离时间短.方法较适于分离较宽范围的DNA片段.     

限制性内切酶指纹-高效毛细管电泳激光诱导荧光法测定原核/真核质粒

采用线性聚丙烯酰胺修饰石英毛细管的高效毛细管电泳无胶筛分技术,对原核/真核质粒用不同限制性内切酶酶切,运用限制性内切酶指纹-高效毛细管电泳激光诱导荧光(REF-HPCE-LIF)检测法同时对内切酶酶切后多个和较长DNA片段进行了检测,电泳缓冲液为1×TBE(pH8.3),阴极电压进样(10kV,5s),分离电压13kV,25℃,激光诱导荧光检测器检测(λex=520nm)。结果表明,所建立的REF-HPCE-LIF方法可对原核/真核酶切后多个和较长DNA片段进行检测,获得了满意的限制性内切酶指纹图谱,能够检测片段大小相差不超过10bp。所建立的方法较琼脂糖电泳分辨率高,可应用在检测多个和较长DNA片段的突变,在诊断肿瘤方面有一定应用前景。     

毛细管电泳聚乙烯吡咯烷酮与羟乙基纤维素混配无胶筛分介质分离DNA片段

本文报道了毛细管电泳聚乙烯吡咯烷酮与羟乙基纤维素混配无胶筛分介质分离较短的 p GEM7Zf(+) Hae DNA片段 (DNA长度为 1 8～ 675bp)。研究表明 ,在 1 %的羟乙基纤维素无胶筛分介质中 ,加入 2 %的聚乙烯吡咯烷酮能显著提高 DNA片段的分辨率和分离效率。在混配无胶筛分介质中 ,聚乙烯吡咯烷酮有两种作用 ,一是动态涂渍 ,降低毛细管内壁对 DNA片段与 DNA荧光插入试剂的吸附 ,改善分离效率 ;二是两种不同长度、性质的线性高分子能形成更为致密的“缠绕网络”,有利于较短的 DNA片段电泳分离。     

聚N-异丙基丙烯酰胺无胶筛分毛细管电泳分离DNA片段

采用0．5％～6％聚N-异丙基丙烯酰胺作为筛分介质,对ФX174／Hae Ⅲ酶切DNA片段毛细管电泳分离进行了研究,结果表明其筛分效果差,信噪比低。然而,添加适量甘露醇可以显著改善分离效率。在3％聚N-异丙基丙烯酰胺中添加2％～6％甘露醇可以取得较好的分离结果,并对甘露醇改善筛分能力的机制进行了探讨。     

癌胚抗原毛细管电泳-化学发光均相免疫分析

建立了一种测定人血清中癌胚抗原的毛细管电泳-化学发光检测的均相免疫分析新方法.采用四苯硼钠增强luminol-H2 O2-HRP体系化学发光的原理,化学发光检测经毛细管电泳分离的,用辣根过氧化物酶(HRP)标记的癌胚抗体及免疫复合物.测定癌胚抗原的线性范围2.0～80.0 μg/L(R=0.9921),检出限为0.1 μg/L(绝对检出限为0.75 fg).     

毛细管电泳检测肺癌基因突变的方法学研究

建立了一种毛细管电泳快速高效检测聚合酶链反应(PCR)扩增产物以及限制性内切酶酶切产物的方法,使其更好地用于基因诊断.以聚环氧乙烷(poly(ethylene oxide),PEO)为筛分介质,用涂层的毛细管柱(37 cm×75 μm,有效长度27 cm)分离pUC19 DNA/MspⅠ(HpaⅡ) Marker标准DNA片段.考察了筛分介质的质量浓度、pH值、毛细管柱的温度和运行电压.在1×TBE (pH 8.2)电泳液、电压15 kV、温度15 ℃,于10 min内成功分离了Marker标准DNA片段.该方法快速、灵敏、准确,用于临床76例肺癌患者正常组织和肿瘤组织p53基因和ras基因点突变情况的检测,结果满意.     

家蚕核多角体病毒基因库

本文报道家蚕核多角体病毒基因组DNA经限制性内切酶SalI酶解,琼脂糖凝胶电泳分离,得0.70至 10.0kb大小不同的29种片段.所得 DNA片段与 SalI酶解之质粒pBR 322 DNA进行体外重组后,经转化大肠杆菌 HB 101菌株,获得带重组质粒克隆株.根据重组质粒DNA 中SalI酶插八片段的分子量、Southern法DNA杂交及多种限制性内切酶酶切点等方法鉴定,证明已将家蚕核多角体病毒DNA的24种不同大小的片段克隆在质粒 pBR 322 中.克隆的 DNA片段总长度占病毒基因组DNA的百分之八十。     

高通量电旋转阵列芯片的构建及其在测定Jurkat细胞介电性中的应用

本文对基于微电极的电旋转电场进行了理论计算。提出了一种先加定位电场,后加旋转电场的实验方法。并根据计算结果构建了一种高通量电旋转阵列芯片及盖片系统。应用该系统,测定了Jurkat细胞的有关介电特性。     

Electrostatic potentials,fields and field gradients from a general crystalline charge density

Explicit expressions for the electrostatic potential, the electric field and the electric field gradient at the nuclear positions of a crystalline lattice are presented. They are derived for a charge density given as an expansion in terms of spherical harmonics around the nuclear sites and as a Fourier series in the interstitial. These expressions can be decomposed into contributions from the spherical region centered around the lattice site of interest, from spherical regions surrounding all the other lattice sites and a contribution from the interstitital region.     

Forces at the nuclei of a molecule in the presence of non-uniform electric field

The interaction Hamiltonian within the Bloch gauge for the potentials of the electric field has been used to define electric multipole moment operators. Perturbation theory has been applied to evaluate the induced electronic moments and electric field at the nuclei in the presence of spatially non-uniform electric fields of high intensity. Multipole nuclear electric shielding tensors have been defined to describe the contributions arising from a non-homogeneous electric field. These quantities are useful to rationalize linear and non-linear responses of a molecule in the presence of intense external electric perturbations.     

Electric-Field-Induced Organic Transformations

Experiments showed that the existence of electric fields in non-redox processes may alter the catalytic activity, rate enhancement, and selection of organic reactions. It is expected that the interaction between electric fields and chemical reactions will create new avenues for producing materials with desired properties in several chemical disciplines, including synthetic organic chemistry, catalysis, nanotechnology, membrane technology, and enzyme catalysis. Specifically, in this review, we discuss the elegant experimental investigations carried out using the scanning tunneling microscope, the interfacial electric field, and designed local electric fields. The results of these studies are remarkable, leading to new information on the function of electric fields in controlling chemical reactivity and selectivity in different reactions and offering a glimpse of the great potential of electrostatic fields. This article not only presents the core concepts of field-induced chemical transformations but also illustrates the potential use of electric field catalysis in chemistry and other fields.     

Calculation of multicenter electronic attraction,electric field and electric field gradient integrals of Coulomb potential over integer and noninteger <Emphasis Type="Italic">n</Emphasis> Slater orbitals

With the help of complete orthonormal sets of - ETOs, where = 1,0, – 1, – 2, ... a large number of series expansion formulas for the multicenter electronic attraction (EA), electric field (EF) and electric field gradient (EFG) integrals of integer and noninteger n Slater type orbitals (ISTOs and NISTOs) is established through the overlap integrals with the same screening constants and the new central and noncentral interaction potentials depending on the coordinates of the nuclei of a molecule are introduced. The convergence of the series is tested by calculating concrete cases for arbitrary quantum numbers, screening constants and location of ISTOs and NISTOs.     

Theoretical investigation on the performance of DNA electrophoresis under programmed step electric field strength: Two‐step condition

Programmed step electric field strength is a simple‐to‐use technique that has already been reported to be effective to enhance the efficiency or speed of DNA electrophoresis. However, a global understanding and the details of this technique are still vague. In this paper, we investigated the influence of programmed step electric field strength by theoretical calculation and concentrated on a basic format named as two‐step electric field strength. Both subtypes of two‐step electric field strength conditions were considered. The important parameters, such as peak spacing, peak width, resolution, and migration time, were calculated in theory to understand the performance of DNA electrophoresis under programmed step electric field strength. The influence of two‐step electric field strength on DNA electrophoresis was clearly revealed on a diagram of resolution versus migration time. Both resolution and speed of DNA electrophoresis under two‐step electric field strength conditions are simply expressed by the shape of curves in the diagram. The possible shapes of curve were explored by calculation and shown in this paper. The subtype II of two‐step electric field strength brings drastic variation on the resolution. Its limitations of enhancement and deterioration of resolution were predicted in theory.     

Numerical simulation of deformation behavior of droplet in gas under the electric field and flow field coupling

The water droplets in the process of electrostatic coalescence are important when studying electrohydrodynamics. In the present study, the electric field and flow field are coupled through the phase field method based on the Cahn–Hilliard formulation. A numerical simulation model of single droplet deformation under the coupling field was established. It simulated the deformation behavior of the movement of a droplet in the continuous phase and took the impact of droplet deformation into consideration which is affected by two-phase flow velocity, electric field strength, the droplet diameter, and the interfacial tension. The results indicated that under the single action of the flow field, when the flow velocity was lower, the droplet diameter was greater as was the droplet deformation degree. When the flow velocity was increased, the droplet deformation degree of a small-diameter droplet was at its maximum size, the large-diameter droplet had a smaller deformation degree, and the middle-diameter droplet was at a minimum deformation degree. When the flow velocity was further increased, the droplet diameter was smaller, and the droplet deformation degree was greater. Under the coupled effect of the electric field and flow field, the two-phase flow velocity and the electric field strength were greater, and the degree of droplet deformation was greater. While the droplet diameter and interfacial tension were smaller, the degree of droplet deformation was greater. Droplet deformation degree increased along with the two-phase flow velocity. The research results provided a theoretical basis for gas–liquid separation with electrostatic coalescence technology.     

白皎煤及其充甲烷样品电极化特征的研究

研究了四川白皎无烟煤在交变和恒电场中的极化特征。结果表明,在恒电场中主要由于位移极化和空间极化的作用,使通过煤和充甲烷煤的电流随时间按下式：Ｉ＝Ｉｓ＋ａｅｂｔ逐渐衰减至一稳定值,且高压电下达到稳定的时间比低电压时要长,ａ随外加电压的升高而增大,衰减系数λ随电压的升高有减小的趋势,高电压时常数ｂ与甲烷平衡压力Ｐ的关系为：１００ｂ＝１０．１１５ｅｘｐ（０．３３８０Ｐ）;在交变电场中,由于极化作用的影响,使得通过煤和充甲烷煤的电流不随时间而变。     

Numerical simulation of droplet coalescence behavior in gas phase under the coupling of electric field and flow field

The coalescence behavior of droplets in an electric field belongs to the important research contents of electrohydrodynamics. Based on the phase field method of the Cahn–Hilliard equation, the electric field and the flow field are coupled to establish the numerical model of twin droplet coalescence in a coupled field. The effects of flow rate, electric field strength, droplet diameter, and interfacial tension on the coalescence behavior of droplets during the coalescence process were investigated. The results show that the dynamic behavior of the droplets is divided into coalescence, after coalescence rupture, and no coalescence under the coupling of electric field and flow field. The proper increase of the electric field strength will accelerate the coalescence of the droplets, and the high electric field strength causes the droplets to burst after coalescence. Excessive flow rates make droplets less prone to coalescence. Under the coupling field, the larger the droplet interface tension, the smaller the droplet diameter, the smaller the flow rate, and the shorter the droplet coalescence time. The results provide a theoretical basis for the application of electrostatic coalescence in gas–liquid separation technology.     

Influence of the electric field on BN conical structures

We apply first‐principles calculations to investigate the effect of the electric field on boron nitride conical structures. The studies involve nanocones with different disclination angles. We applied fields of 0.3 V/Å and 0.6 V/Å parallel to the cone axis. It is shown that a small field does not affect the stability of such structures; however, for a larger field, a decrease of 0.1 eV/atom for all structures is observed. We also find modification in the energy gap due to the intensity of the electric field. The bandgap decreased proportionally to the intensity of the electric field, indicating that these results have consequences in the field emission properties of these structures. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006