毛细管电泳前沿分析法研究钾离子与18-冠醚-6体系相互作用

采用毛细管电泳前沿分析(CE／FA)法，利用间接紫外检测方法，在pH为5．10，运行电压为30kV，缓冲溶液组成为咪唑和醋酸的条件下，测定了钾离子与18-冠醚-6体系的相互作用参数，结合常数对数值lgK=3．50；在同样条件下用峰漂移法作对照实验，求得体系的结合常数对数值lgK=3．40，结果与前沿分析法基本一致。验证了两种方法测定结果的正确性。     

稀土离子(Ⅲ)与牛血清白蛋白结合作用的研究

模拟生理条件研究了稀土离子(Ⅲ)与牛血清白蛋白(BSA)的结合性质.荧光光谱结果表明,Tb与BSA形成1∶2配合物,表观络合常数lgK=7.93,并由pH电位法得出相近结果.用平衡透析法确定Pr与BSA结合的高亲合位点数为2,低亲合位点数大于6,两类条件结合常数lgK1=5.157,lgK2=3.435.由NMR法通过²³Na弛豫时间的改变可知稀土与BSA络合后蛋白质体积膨胀,活动性增加,相关时间τ_c减小.     

毛细管电泳用于不稳定络合体系形态分析

1 引言毛细管区带电泳技术,不存在色谱分析中组分与固定相间的作用,从而可最大可能地保持体系中各易变形态的浓度和分布,使之用于元素的易变形态分析和不稳定络合体系稳定常数测定.使用“峰漂移法”的实验模型,在对一级络合体系的研究基础上,推广到多级逐步络合体系.该方法不是基于分离测定,而是通过缓冲液组分对各种形态物电泳淌度的影响,演算出n级逐步络合的不稳定络合体系的各级逐步络合平衡常数,从而求得各易变组分的浓度和分布.本文将该方法应用于乙酰丙酮与镁离子这种二级逐步络合的不稳定体系.     

毛细管电泳法研究牛血清白蛋白与盐酸异丙肾上腺素的相互作用

本研究分别采用区段-区段动力学毛细管电泳法(Plug-Plug Kinetic Capillary Electrophoresis,ppKCE),及以药物为添加剂的亲和毛细管电泳法(Affinity Capillary Electrophoresis,ACE)对盐酸异丙肾上腺素(Hydrochloric Acid Isoproterenol,HAI)与牛血清白蛋白(Bovine Serum Albumin,BSA)的结合作用进行研究。实验结果显示,ppKCE法可同时测得HAI与BSA相互作用体系的结合速率常数kon和离解速率常数koff分别为163.60L·mol-1·s-1、3.50×10-2±0.95×10-2s-1(n=3)。ppKCE法和ACE法测得HAI与BSA的结合常数Kb分别为4.67×103 L·mol-1、6.02×103 L·mol-1,两种方法所得结果能够较好吻合。证明毛细管电泳法在药物-蛋白相互作用研究领域的可靠性,可用于测定药物与蛋白的相互作用,从而用于新药筛选研究。     

亲和毛细管电泳间接紫外检测法测定金属络合物的亲和常数

 采用亲和毛细管电泳间接紫外检测方法 ,根据“峰漂移”模型 ,通过迁移时间的测定 ,可以获得在水体系中有极低亲和常数的金属络合物的亲和常数。将该方法分别应用于镁离子 柠檬酸体系和锰离子 酒石酸体系 ,在 pH为 5 .0 1,运行电压为 2 0kV ,缓冲溶液组成为咪唑和醋酸的条件下 ,测定了缓冲溶液中加入不同浓度配体后金属离子迁移时间的变化 ,经过数据处理后得出它们的亲和常数对数值分别是 3.2 7和 2 .2 8,与文献值较为一致。该方法适用于结合比为 1∶1的金属络合物的亲和常数的测定。     

高氯酸铊-18冠6-水体系的核磁共振研究

本文用核磁共振法测定了高氯酸铊-18冠6-水体系的各个热力学参数.该体系的络合稳定常数、热焓、熵和吉氏函数在25.1℃时的数值分别为:lgK=2.11±0.02、△H=-4.49±0.17kcal/mol、△S=-5.35±0.54cal/mol和△G⁰=-2.88kcal/mol。所得结果与用量热法测得的数值一致。     

药物与细胞膜相互作用的毛细管电泳方法研究

以细胞膜在毛细管内构成假固定相,建立一种基于毛细管电泳测定药物与细胞膜相互作用参数的方法．以西酞普兰和兔红细胞膜为相互作用模型,以不同浓度的细胞膜混悬液为电泳缓冲液,采用峰漂移法,并结合Scatchard分析,测得西酞普兰与兔红细胞膜的结合常数为0．977g^-1·L．该方法简单、快速,为研究药物与细胞膜的相互作用提供了新的技术手段,为高通量筛选药物膜通透性和活性,以及评价药物在体内吸收提供一种新的方法．     

毛细管电泳测定物质三元相互作用体系的结合系数

毛细管电泳一般只能对二元结合体系的结合常数进行测定。研究了三元相互竞争体系的毛细管电泳测定方法,测定了金属锌离子与酒石酸和半胱氨酸以及锌离子与乳酸和半胱氨酸两个三元结合体系的结合常数,并以此比较了两种锌形态与半胱氨酸结合能力的大小。本法可用于测定两配体相互竞争结合体系的结合常数。     

分光光度法测定I3-的稳定常数

用分光光度法测定了反应I2+I-=I3-的平衡常数.在350nm处,I3-的摩尔吸光系数为2.3×104L*mol-1*cm-1,而I2和I-在这一波长没有吸收,据此提出了用分光光度法测定I3-稳定常数的方法.研究了适当的实验条件,测定结果为lgK=2.96.     

紫外-可见分光光度法测定溴代卟啉的质子化反应常数

采用紫外-可见分光光度法研究了溴代卟啉(H2TPPBrx)在N,N-二甲基甲酰胺(DMF)中的吸收光谱性质,并测定了其在非水溶剂DMF中与HClO4反应的质子化常数。结果表明H2TPP,H2TPPBr2在DMF溶剂中与高氯酸反应得到两个质子生成[H4TPP]2 和[H4TPPBrx]2 ,而H2TPPBr3,H2TPPBr4只能得到一个质子生成[H4TPPBrx] 和[H4TPPBrx] ,其质子化常数分别为:lgK1=3.28,lgK2=2.86,lgK3=2.16,lgK4=1.93。     

用从头算量化参数预测多氯代二苯并呋喃的1gKow

采用G98W程序包中的HF方法和6-31g(d)基组对135个多氯代二苯并呋喃(PCDFs)分子和二苯并呋喃进行了全几何优化计算．以计算所得的分子轨道能量、原子电荷作为PCDFs分子结构描述符，运用多元线性回归技术建立了PCDFs的lgKow与上述参数的四元线性方程，相关系数为0．9306，标准偏差为0．1849，用Jackknife法检验该模型的稳健性好，并对未有实验数据的85个PCDFs的lgKow进行了预测．     

Solving the Schrodinger equation for helium atom and its isoelectronic ions with the free iterative complement interaction (ICI) method

The Schrodinger equation was solved very accurately for helium atom and its isoelectronic ions (Z=1-10) with the free iterative complement interaction (ICI) method followed by the variational principle. We obtained highly accurate wave functions and energies of helium atom and its isoelectronic ions. For helium, the calculated energy was -2.903,724,377,034,119,598,311,159,245,194,404,446,696,905,37 a.u., correct over 40 digit accuracy, and for H(-), it was -0.527,751,016,544,377,196,590,814,566,747,511,383,045,02 a.u. These results prove numerically that with the free ICI method, we can calculate the solutions of the Schrodinger equation as accurately as one desires. We examined several types of scaling function g and initial function psi(0) of the free ICI method. The performance was good when logarithm functions were used in the initial function because the logarithm function is physically essential for three-particle collision area. The best performance was obtained when we introduce a new logarithm function containing not only r(1) and r(2) but also r(12) in the same logarithm function.     

Voltammetric study of the interaction of pentoxifylline (PTX) with Zn(II) in the presence and absence of cysteine

The interaction of pentoxifylline (PTX) with Zn(II) in the presence and absence of cysteine at physiological pH (7.40) was investigated for the first time by square-wave and cyclic voltammetry techniques. The Zn(II)–PTX complex was found to be an electroinactive inert complex, the composition of the formed complex is 1?:?1 (metal?:?ligand), and the logarithm of its stability constant (log β_1?:?1) was determined as 3.46 by direct monitoring of the current of free zinc(II). The logarithm of the stability constant (log β_1?:?2) and stoichiometry of the complexation of Zn(II) with cysteine were determined to be 9.94 and 1?:?2, respectively. The stability constants were in agreement with those calculated from electronic spectral data. In the presence of cysteine, Zn(II)–PTX dissociated and an irreversible peak for Zn(II)–cysteine appeared at ?1.342?V. Cysteine prevents complex formation of Zn(II) with PTX.     

Determination of the activation energy for unimolecular dissociation of a non-covalent gas-phase peptide: Substrate complex by infrared multiphoton dissociation fourier transform ion cyclotron resonance mass spectrometry

The activation energy for the unimolecular dissociation of a non-covalent supramolecular complex between an Artificial Cationic Receptor A ([Gua-Val-Val-Val-Amide]+, in which Gua is guanidiniocarbonyl pyrrole) and an Anionic Tetrapeptide B ([N-Acetyl-Val-Val-Ile-Ala]-) has been determined by measurement of the dissociation rate constant as a function of infrared CO2 laser power density. Singly-charged quasimolecular [A + B + H]+ ions are isolated, stored in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer, and irradiated by IR photons. The rate constant for dissociation of the non-covalent complex is determined at five different laser power densities. A plot of the natural logarithm of the first-order rate constant versus the natural logarithm of the laser power density yields a straight line, the slope of which provides an approximate measure of the activation energy (Ea(laser)) for dissociation. Ea(laser) is calculated by a relationship derived earlier by Dunbar and with a newly proposed equation by Paech et al. The results of the two approaches deliver significantly different activation energy values for the unimolecular dissociation of the non-covalent complex. We obtain EaI(laser) = 0.67 eV (Dunbar approximation) and EaII(laser) = 1.12 eV (Paech et al. approximation). Differences between the two approaches are discussed with respect to non-covalent complexes.     

SPECTROPHOTOMETRIC STUDY OF BIMETALLIC TERNARY COMPLEX OF LANTHANUM——COPPER WITH ALIZARIN FLUORINE BLUE

The bimetallic ternary complex formation in the aqueous solution of La and Cu with alizarin fluorine blue (AFB) was studied by spectrophotometry.The ternary complex LaCu3(AFB)3 has maximum light absorption at 550nm.The colour reaction selectivity is fairly good and the method can be applied to the direct photometric determination of copper in lanthanum or some pure metals.A new mathematical approach to the treatment of spectrophotometric data for differentiation between mononuclear and polynuclear in solution is presented.The improvable fixed logarithm method is for complexes of the type MmBn(m=n) or MmBn(m=n).We report that La(Ⅲ) combines with AFB at pH 4.5 to form a single complex,withm=n=2,La2(AFB)2.     

Is HOMO Energy Level a Good Parameter to Characterize Antioxidant Activity

As free radicals cause degradation of many industrial materials, degeneration of foods,and scores of diseases, such as inflammation, neurodegeneration, and tUmors, selectinghighly efficient antioxidants with low toxicity is of great importance and in fact, has beenpaid much attention'-3. Moreover, it has been pointed out that theoretical methods willaccelerate the selection of new antioxidants4.5. Indeed, various theoretical parametershave been found appropriate to characterize the free radica…     

Effect of the pH on the complexation of Cu(II), Ni(II) and Fe(III) Ions by a vine leaf litter extract by fluorescence quenching

An extract of dead vine leaves (vitis viniferal) (VLE) was obtained by the extraction procedure for fulvic acids and its interaction (at a concentration of 25mg/L in 0.1 M KNO₃) with the Cu(II), Ni(II) and Fe(III) ions was studied in the pH range between 3 and 6. This interaction was monitored by synchronous molecular fluorescence, since bands due to the fluorescent ligands undergo quenching upon complex formation. After the chemometric isolation of the quenching profiles from the raw spectra by a self-modeling mixture analysis, SIMPLISMA, they were analyzed by two methods: (i) graphical procedures based on the Stern-Volmer model; and (ii) a non-linear least-squares procedure. For the Cu(II) and Ni(II) ions, the treatment by these two methods provided similar values both for the logarithm of the conditional stability constants (log Kc) and the percentage of fluorescent structures that do not participate in the complexation. The log Kc were (standard deviations in parenthesis): Cu(II) ion, 2.4 (3), 3.37(3), 4.4(1) and 4.92(9), respectively, for pH = 3, 4, 5 and 6; Ni(II)ion, 2.9(1), 3.3(2), and 4.09(3), respectively, for pH = 4, 5 and 6. For Fe(III) an interaction with VLE was observed, but no values for Kc could be obtained.     

镧-铜-茜素氟蓝杂多核络合物的分光光度法研究

镧、铜和茜素氟蓝可生成杂多核络合物,本文用校正的斜率此法测定杂多核络合物的组成比;用改进的限定对数法测定镧-茜素氟蓝同多核络合物的实际组成。     

Spectroscopic study of chloranil charge-transfer complexes of amino acids and related compounds

The absorption maxima, molar absorptivities, infrared spectra, compositions, formation constants, and pH dependence of amino acid—chloranil complexes have been determined with purified chloranil The n-π charge-transfer interaction depends on the presence of an unprotonated amino group; pH 9 is optimal for complex formation, but once formed, the complex is stable in a highly acidic medium and may be quantitatively extracted by hexanol. The molar absorptivities of the chloranil complexes of glycine, iminodiacetic acid, NTA, EDTA, DTPA and TTHA were measured. There is a linear relationship between the logarithm of the molar absorptivities of their chloranil complexes and the number of carboxylic groups in the molecule. There is an inverse linear relationship between the molar absorptivities of chloranil—metal—EDTA complexes and the logarithm of the stability constants of the EDTA chelates. This leads to a new method of determining the stability constants of complexes involving a nitrogen-donating group.