荧光光谱研究CBAP与人血清白蛋白的相互作用

在模拟人体生理条件下,用荧光光谱和紫外可见吸收光谱法研究了不同温度下4-(2-羧基苯偶氮)-连苯三酚(CBAP)与人血清白蛋白(HSA)的相互作用.结果表明,CBAP对HSA的荧光猝灭属静态猝灭.通过288、293、298 K时的荧光猝灭,得出CBAP与HSA的结合常数K分别为1.62×106,3.97×105和3.56×105,结合位点数n=0.92(平均值).据F(o)rster非辐射能量转移理论计算出CBAP与HSA的结合距离r=1.44 nm,由热力学参数焓变和熵变,推断两者反应时氢键和范德华力可能起主要作用.运用同步荧光和三维荧光技术分析了CBAP对HSA构象的影响,表明CBAP的加入改变了HSA中酪氨酸残基和色氨酸残基的构象.     

氢键对物质性质的影响及应用

氢键不属于化学键,也不属于范德华力,是介于化学键和范德华力之间的一种由氢原子参与成键的特殊键型。氢键的键能较小,但其存在却对物质的性质,结构等方面有很大影响。故对氢键的研究应用也为人们所关注。     

两种β-环糊精与冰片包结过程的动力学模拟

为研究冰片与β-环糊精(β-CD)或羟丙基-β-环糊精(HP-β-CD)包结机理,并解释冰片与两者的相溶解度关系,利用Accelrys公司开发的Materials Studio 4.0进行分子动力学模拟实验。在Compass力场下建立晶胞模型并进行恒温恒容(NVT)和恒温恒压(NPT)模拟得出能量图。两个能量图均显示发生包结作用的范德华力远大于氢键与疏水作用力之和,这证明冰片与环糊精发生包结作用的主要驱动力是范德华力。能量图显示:冰片与β-环糊精包结物的结合能低,而冰片与羟丙基-β-环糊精包结物的结合能高;故冰片与β-环糊精形成不溶性包结物,冰片与羟丙基-β-环糊精形成可溶性包结物。     

席夫碱铜配合物合成及与DNA/蛋白质作用的研究

利用2-吡啶甲醛、N,N-二甲基乙二胺制备了一种新的席夫碱铜配合物,并通过X-射线单晶衍射、元素分析和ESI-MS对其结构进行分析.晶体结构分析表明,配合物呈现扭曲的四方锥构型.用紫外-可见吸收光谱、荧光光谱和圆二色光谱研究了配合物与小牛胸腺DNA(CT-DNA)和人血清白蛋白(HSA)的结合性质.结果表明:配合物以插入的方式与DNA相互作用,且配合物与HSA的相互作用为静态猝灭机制,分子间作用力为氢键和范德华力.     

对范德瓦耳斯气体引力势能的一种谬论的深入分析

对范德瓦耳斯气体引力势能理解中的一种错误进行深入分析,根据统计的思想,用两种方法证明了范氏气体摩尔引力势能的表达式,并指出它的适用条件是短程弱引力分子气体;通过对比范氏固体和范氏气体引力势能的计算过程,揭示了谬论的错误所在;从概率论的角度分析了膨胀时气体引力势能变化量有别于固体的根本原因。     

聚合物的溶解与选择性分子间引力

将控制论的结构适应性原理引入高分子学科，解释了一些范德华力、氢键等化学基本理论未能恰当解释的聚合物溶解现象。     

Subnormal osmolarity may underlie microcephaly in Zika viral infections

Leucines accounted for 9.144%of the Zika viral full length protein with over 300 leucines.The amino acid residue lacks γ methyl group,thus devoid of the σ-σ hyperconjugation in beta carbon,as well as strong van der Waals interactions with the carbonyl group of leucine.This results in the low cation affinity with carbonyl oxygen,and un-enhanced secondary chemical bonding with the oxygen atom.The subnormal osmolarity generated in the presence of leucine rich proteins and degraded peptides would affect the development of the brain.A carbohydrate diet could be effective in the prevention of viral infections.     

19世纪人类有关语言本质问题的探索历程

19世纪,人类有关语言本质问题的认识,在已有语言工具论、符号论等有关理论继续得以向前发展的同时,又出现了语言世界观说、语言生物机体说,以及语言的本质在于交际等一些新的思想火花。     

高压下β硼电输运行为中的晶界效应

利用交流阻抗谱方法,讨论了高压下晶界效应对β硼电输运性质的影响,最高压力为28.3GPa.结果表明：晶粒电阻和晶界电阻均随压力逐渐减小;晶界电阻对总电阻的贡献随压力逐渐减小,当压力达23.9GPa时,随着范德瓦尔斯力及晶界相互作用的出现,晶界传导几乎消失.     

Teaching chemical bonding through jigsaw cooperative learning

This study examined the effectiveness of jigsaw cooperative learning in teaching chemical bonding at tertiary level. This study was carried out in two different classes in the Department of Primary Science Education of Atatürk University during the 2005–2006 academic year. One of the classes was the non‐jigsaw group (control) and the other was the jigsaw group (experimental). Students in the jigsaw group were divided into four ‘home groups’ since chemical bonding is divided into four subtopics (Modules A, B, C and D). Each of these home groups consisted of four students. The subjects covered were ionic bonding (Module A), covalent bonding (Module B), hydrogen bonding and van der Waals (Module C) and basic concepts about bonds (Module D). The main instrument for obtaining data was the Chemical Bonding Achievement Test (CBAT), which was applied to both groups. The CBAT was divided into four modules (A, B, C and D), in which each module consisted of five questions (four multiple‐choice and one open‐ended). The data obtained indicated that the students in the jigsaw group were more successful than those in the non‐jigsaw group.     

谈谈对气体的范德瓦耳斯方程中压强p的理解

本文将对准真实气体的范德瓦耳斯状态方程中压强p,提出作者的理解,并指出部分现行教材中对此问题阐述的不足之处。     

Inhibitory mechanism of angiotensin-converting enzyme inhibitory peptides from black tea

The aim of this work is to discover the inhibitory mechanism of tea peptides and to analyse the affinities between the peptides and the angiotensin-converting enzyme(ACE) as well as the stability of the complexes using in vitro and in silico methods. Four peptide sequences identified from tea, namely peptides I, II, III, and IV, were used to examine ACE inhibition and kinetics. The half maximal inhibitory concentration(IC_(50)) values of the four peptides were(210.03±18.29),(178.91±5.18),(196.31±2.87), and(121.11±3.38) μmol/L, respectively. The results of Lineweaver-Burk plots showed that peptides I, II, and IV inhibited ACE activity in an uncompetitive manner, which requires the presence of substrate. Peptide III inhibited ACE in a noncompetitive manner, for which the presence of substrate is not necessary. The docking simulations showed that the four peptides did not bind to the active sites of ACE, indicating that the four peptides are allosteric inhibitors. The binding free energies calculated from molecular dynamic(MD) simulation were-72.47,-42.20,-52.10, and-67.14 kcal/mol(1 kcal=4.186 kJ),r espectively. The lower IC_(50) value of peptide IV may be attributed to its stability when docking with ACE and changes in the flexibility and unfolding of ACE. These four bioactive peptides with ACE inhibitory ability can be incorporated into novel functional ingredients of black tea.     

荧光法研究司他夫定与牛血清白蛋白的结合作用

在Tris缓冲溶液（pH7．1）体系中,用荧光光谱技术研究水溶液中司他夫定与牛血清白蛋白的结合作用．结果表明,司他夫定对牛血清白蛋白内源荧光产生较强的荧光猝灭作用,根据不同温度下司他夫定对牛血清白蛋白的荧光猝灭作用,证明其为静态猝灭机制,运用位点模型计算出298K,310K时其结合常数KA（分别为1．01×10^4,4．17×10^4L·mol^-1）和结合位点数n（分别为0．99,0．93）,根据热力学参数确定其作用力以氢键或VanderWall＇s作用为主;蛋白质变性剂尿素的存在导致上述荧光猝灭效率减少;运用FSster偶极-偶极非辐射能量转移原理,计算了司他夫定与牛血清白蛋白的结合距离r为3．79nm．     

Investigating Interaction Between Biochanin A and Human Serum Albumin by Multi-spectroscopic and Molecular Simulation Methods

Biochanin A(BCA), the most abundant isoflavone in chickpeas, presents a wide range of biological activities, such as hypolipidaemic, anti-oxidative, antiproliferative, and estrogen-like effects. We investigated the interaction between BCA and human serum albumin(HSA) via several techniques. UV–Vis absorption spectroscopy verified the conformational variation of HSA after BCA addition, and fluorescence spectroscopy revealed the relevant binding parameters. Circular dichroism spectroscopy was used to estimate the secondary structural changes of HSA with and without BCA. Molecular docking and dynamics simulations were then applied to study the characteristics of HSA with BCA. Energy decomposition analysis was used to prove that Trp214 in subdomain ⅡA of HSA is the most likely binding site of BCA. Van der Waals forces and hydrophobic interactions may play important roles during the binding process. All of our results showed that BCA presents significant binding affinity to HSA, thus confirming that the role of HSA has as an efficient transporter of biomolecules.     

范德瓦尔斯频移及线型畸变现象

从理论上研究了囚禁于两电介质间薄原子蒸汽的频率调制吸收光谱中范德瓦尔斯频移及线型畸变现象,发现在频率调制情形下频移很明显,线型则由对称类色散型转为非对称类吸收型。采用频率调制的方法解决了在很多情形下采用直接法或吸收法不易实现对vdW作用势进行精确测量的难题。     

4-X-N-Y-6-氮杂雄-4-烯-3-酮衍生物的QSAR研究

分别采用人工神经网络BP算法（网络结构为3-9-1）和线性回归分析方法对17个4-X-N-Y-6-氮杂雄-4-烯-3-酮衍生物在4℃时与小牛子宫雌激素受体的亲合力参数Iog1/K（iKi为衍生物对3BHSD的抑制常数）与分子的范德华体积V、最高被占据分子轨道能量EHOMO和9号碳原子的净电荷Q之间建立了QSAR模型,ANN模型的相关系数R=0.9999,标准偏差SD=0.0014。MLR模型的相关系数R=0.9470,标准偏差SD=0.4459。结果表明人工神经网络是一种比较精密的拟合方法,具有良好的预测效果。     

Growth Mixture Modeling With Nonnormal Distributions: Implications for Data Transformation

This study investigated the extent to which class-specific parameter estimates are biased by the within-class normality assumption in nonnormal growth mixture modeling (GMM). Monte Carlo simulations for nonnormal GMM were conducted to analyze and compare two strategies for obtaining unbiased parameter estimates: relaxing the within-class normality assumption and using data transformation on repeated measures. Based on unconditional GMM with two latent trajectories, data were generated under different sample sizes (300, 800, and 1500), skewness (0.7, 1.2, and 1.6) and kurtosis (2 and 4) of outcomes, numbers of time points (4 and 8), and class proportions (0.5:0.5 and 0.25:0.75). Of the four distributions, it was found that skew-t GMM had the highest accuracy in terms of parameter estimation. In GMM based on data transformations, the adjusted logarithmic method was more effective in obtaining unbiased parameter estimates than the use of van der Waerden quantile normal scores. Even though adjusted logarithmic transformation in nonnormal GMM reduced computation time, skew-t GMM produced much more accurate estimation and was more robust over a range of simulation conditions. This study is significant in that it considers different levels of kurtosis and class proportions, which has not been investigated in depth in previous studies. The present study is also meaningful in that investigated the applicability of data transformation to nonnormal GMM.     

Molecular modeling study of the effect of base methylation on internal interactions and motions in DNA and implication to B-Z conformation change

1. Introduction Experimental studies have shown that a DNA molecule with alternating pyrimidine-purine sequence can adopt a left-handed, double-helical Z-DNA conformation [1,2]. Such structural changes of DNA occur as a consequence of environmental conditions such as at salt concentration above 4 mol/L NaCl [1,2] or through certain chemical modification such as methylation [1] or bromination [2,3] of bases at physiological conditions. These structural changes and chemical modifications …     

Affinity Purification of Insulin by Peptide-Ligand Affinity Chromatography

The affinity heptapeptide(HWWWPAS)for insulin,selected from phage display library,was coupled to EAH Sepharose 4B gel and packed to a 1-mL column.The column was used for the affinity purification of insulin from protein mixture and commercial insulin preparation.It was observed that the minor impurity in the commercial insulin was removed by the affinity chromatography.Nearly 40 mg of insulin could be purified with the 1-mL affinity column.The results revealed the high specificity and capacity of the affinity column for insulin purification.Moreover,based on the analysis of the amino acids in the peptide sequence,shorter peptides were designed and synthesized for insulin chromatography.As a result,HWWPS was found to be a good alternative to HWWWPAS,while the other two peptides with three or four amino acids showed weak affinity for insulin.The results indicated that the peptide sequence of HWWWPAS was quite conservative for specific binding of insulin.     

铁配合物[Fe（C_（12）H_8N_2）_3]（C_6H_6N_2S_2O_6）·4H_2O的合成及晶体结构表征

采用水溶液法,合成了铁配合物[Fe（C12H8N2）3]（C6H6N2S2O6）.4H2O,该配合物晶体属三斜晶系,P-1空间群,晶胞参数是：a=12.8789（12）,b=13.3808（13）,c=14.859（2）,α=104.558（2）°,β=100.780（2）°,γ=107.5760（10）°,V=2264.8（5）3,Z=2.铁离子周围有6个由1,10-邻菲罗啉提供的氮原子与之配位形成畸变的八面体的配位构型.相邻结构单元中的邻菲罗啉分子存在着弱的π-π堆积作用,没有参与配位的邻苯二胺-3,5-二磺酸根离子与结晶水分子通过氢键将配合物扩展为二维超分子结构.