光谱法研究金属离子与肿瘤抑制蛋白p53的DNA结合结构域的相互作用

利用荧光滴定法研究了9种金属离子与序列特异性的DNA结合结构域(p53DBD)的结合反应,其结合能力依次为Fe3+＞Zn2+＞Cu2+＞Ca2+＞Mg2+＞Ba2+＞Mn2+＞Ni2+＞Co2+.圆二色谱研究结果表明,Ba2+, Ca2+, Co2+, Mn2+及Ni2+并未引起蛋白二级结构变化; Zn2+, Mg2+及Fe3+诱导蛋白结构细微调整;而Cu2+结合导致蛋白螺旋结构大量丢失.ANS结合研究结果表明, Mg2+与Zn2+相似,诱导p53DBD蛋白表面疏水性增强,而Fe3+引起p53DBD蛋白表面疏水性降低.因此,Mg2+和Fe3+可能是影响或调节p53活性的潜在因子之一.     

基于脱氧核酶的新型铅离子荧光探针

将荧光猝灭基团修饰的17E脱氧核酶(17E DNAzyme)与荧光基团修饰的底物链通过6个脱氧核苷酸相连, 得到了一种新型的对Pb2+敏感的荧光探针. 由于DNAzyme与底物链发生分子内杂交, 荧光基团与猝灭基团相互靠近, 导致荧光猝灭. 当Pb2+存在时, DNAzyme被激活, 底物链被切断后释放出荧光基团标记的DNA片段, 从而产生明显的荧光信号. 据此可在常温下快速检测Pb2+, 检测下限为10 nmol/L. 在Zn2+, Mn2+, Co2+, Cd2+, Cu2+, Mg2+和Ni2+等多种二价金属离子中, 除Zn2+, Mn2+和Cd2+略有干扰外, 其它几种金属离子均无响应, 表明该荧光探针对Pb2+具有良好的选择性.     

Ni2+和Cd2+跨人红细胞膜的比较研究

以往对金属离子跨红细胞膜转运多集中在体内的宏量金属离子, 如Na+, K+, Ca2+, Mg2+及某些必需的重金属元素Fe2+, Cu2+, Zn2+等[1～3], 对其它重金属离子的跨膜转运研究较少. 我们曾研究了具有不同电荷的Co(Ⅲ)配合物的红细胞摄入动力学及机理[4]. 在此基础上进一步选择离子电荷数相同, 但电子组态不同的两个金属离子Ni2+和Cd2+为研究对象. Ni2+为d8组态, 动力学上是惰性的, 为体内必需的微量元素; 而Cd2+为d10组态, 动力学上是活性的, 却为有毒重金属, 本研究比较了它们跨人红细胞膜传递的动力学以及其与人红细胞作用的差异性.     

A New Fluorescent Chemosensor for Cu2+ Based on Acridine-1, 8-dione Fluorophore

合成了以吖啶为发色团,以二吡啶甲基胺为离子受体的Cu2+荧光探针,并进行了表征及离子识别性能的研究。研究表明该化合物对Cu2+具有良好的识别性能,同时相对于Na+, K+, Ca2+, Cd2+, Co2+, Hg2+, Mg2+, Mn2+, Ni2+, Fe3+, Zn2+, Ag+ and Pb2+.等金属离子具有良好的选择性。并研究了EDTA作用下荧光恢复性能,结果表明该化合物具有Cu2+引发的荧光开光功能。     

磷酸二甲酯阴离子与二价金属离子相互作用的研究

在B3LYP/6-31G(d, p)水平上,用全电子分别研究了Mg2+、Ca2+、Mn2+、Co2+、Ni2+、Cu2+和Zn2+与磷酸二甲酯(DMP-)“双齿”配位模式下的相互作用,且由4个水分子((H2O)4)“饱和”各金属离子六配位模式下的其它位点。结果表明:这种配位模式下,DMP-对上述金属离子的选择性顺序为:Cu2+>Ni2+>Zn2+>Co2+>Mg2+>Mn2+>Ca2+,和Irving-Williams序列基本一致。且具有未充满d层轨道的金属对配体的变化“响应”明显。通过NBO(自然键轨道)方法对配合物电荷布居分析可得出主族金属离子与配体间以静电相互作用为主,非主族金属离子配合物中存在一定的共价作用的结论,同时关于配合物各部分间键轨道相互作用的分析部分的反映了金属离子与配体的作用实质。     

稀土离子与2,9-二甲基-1,10-菲罗啉的α-氨甲基吡啶衍生物的二元配合物的稳定性研究

在25 0±0.1℃,0.1mol·L-3NaClO4的条件下,用pH电位滴定法测定了配体2,9 二甲基 1,10 菲罗啉的α 氨甲基吡啶衍生物 N,N′ 二 α 吡啶甲基 1,10 菲罗啉 2,9 二甲胺(L)在水溶液中分别与稀土离子Ln(Ln=La3+,Ce3+,Pr3+,Nd3+,Sm3+,Eu3+,Gd3+,Tb3+,Dy3+,Ho3+)的二元配合物的稳定常数。提出了配合物在溶液中的可能结构。对金属离子对配合物稳定性的影响进行了详细的讨论,并比较讨论了稀土离子和其它金属离子如Co2+,Ni2+,Cu2+等与配体L的所形成配合物的稳定性差异的原因。运用线性回归,对有放射性的Pm3+与相应配体的二元配合物的稳定常数进行了推测。     

基于短肽自组装与共组装的纳米纤维人工水解酶

将水解酶活性中心催化三联体氨基酸(His/Ser/Asp)引入9-芴亚甲氧羰基苯丙氨酸二肽(Fmoc-FF)双亲短肽序列中,利用短肽的自组装性能,构建了具有对硝基苯酚乙酸酯水解活性的超分子纳米纤维人工水解酶.研究结果表明,形成规则的纳米纤维结构是获得催化活性的必要条件.9-芴亚甲氧羰基(Fmoc)基团间的弱相互作用促使β-折叠二级结构的形成.通过对比天然水解酶的米氏动力学方程、最适催化温度及p H结果可知,所制备的超分子纳米纤维人工水解酶具有与天然酶相似的酶学性质.金属离子Ca2+和Ba2+对人工水解酶活性具有激活作用,而Mg2+,Ni2+,Co2+,Cu2+和Zn2+则抑制酶活性.     

LaCl3对轮藻光合色素含量及抗氧化酶活性的影响

研究了LaCl3对轮藻光合色素含量及抗氧化酶活性的影响,La3+浓度分别为0,0.2,1.0和5.0 μmol·L-1.结果表明0.2和5.0 μmol·L-1La3+处理降低了轮藻叶绿素b的含量,5.0 μmol·L-1 La3+处理降低了叶绿素a+b的含量;类胡萝卜素含量在1.0 μmol·L-1 La3+处理组显著高于对照.随着La处理浓度的提高超氧化物歧化酶的活性逐渐升高,处理组谷胱苷肽过氧化物酶活性均显著高于对照,且在1.0 μmol·L-1La处理组达到最大值,0.2和5.0 μmol·L-1 La3+处理将抑制过氧化氢酶活性,其变化规律与叶绿素b相似.实验浓度的La3+处理可能引起了轮藻植株的氧化损伤,作为应激反应,GSH-Px酶活性及类胡萝卜素含量的升高在一定程度上缓解了氧化损伤.     

常见金属离子对漆酶酶活的影响

检测了14种不同的金属离子对两种漆酶(laccaseA和laccaseB,简称LacA和LacB)活性的影响.结果表明:Al3+,Fe3+,Ag+,Hg2+对两种漆酶的活性都有抑制作用,其中Fe3+,Ag+的抑制作用最强,酶活完全损失;Mg2+,Cu2+对两种漆酶的活性有激活作用.     

A new perylene diimide-based colorimetric and fluorescent sensor for selective detection of Cu~(2+) cation

A new perylene diimide (PDI) ligand (1) functionalized with a dipicolylethylenediamine (DPEN) moiety was synthesized and first used as a colorimetric and fluorometric dual-channel sensor to specifically detect the presence of Cu2+ over a wide range of other cations. The solution of 1 (10 μmol/L) upon ad-dition of Cu2+ displayed distinguishing pink color compared with other cations including K+,Ni2+,Ca2+,Mn2+,Na+,Sr2+,Zn2+,Co2+,Cd2+,Mg2+,Cr3+,Ag+,and Ba2+,indicating the sensitivity and selectivity of 1 to Cu...     

Promotion of Activity and Thermal Stability of Chloroperoxidase by Trace Amount of Metal Ions (M2+/M3+)

The effect of M²⁺ (Zn²⁺, Cu²⁺, Cd²⁺, Mn²⁺, Pb²⁺) and M³⁺ (Cr³⁺, La³⁺, Fe³⁺, Ce³⁺, Y³⁺, Al³⁺) metal ions on the activity and thermal stability of chloroperoxidase (CPO) was investigated in this work. It was found that the lower concentration of metal ions was favorable to CPO activity whereas the higher concentration reversed the results. CPO activity could be increased to 116.4–127.1 % in the presence of a trace amount of these M²⁺/M³⁺ metal ions at a concentration range of 0–25 μmol L^?1 after 2 h of incubation at 25 °C. The activating effect of M³⁺ is better than that of M²⁺, and Cr³⁺ was mostly efficient. The thermal stability of the enzyme was also improved significantly. Only 30.3 % of CPO activity was retained at 50 °C whereas 82.6 % of CPO activity was maintained in the presence of Cr³⁺ after 2 h of incubation at the same temperature. The activation of CPO by metal ions at their low concentration was studied through intrinsic fluorescence, circular dichroism (CD), and UV–Vis spectra assay. A favorable environment around the active site was achieved in the presence of metal ions. Intrinsic fluorescence and CD spectra indicated that the α-helix structure of CPO was strengthened in metal ion-contained media. More exposure of the heme ring was achieved for easy access of the substrate, which was suggested by UV–Vis spectrum analysis. This strategy for enhancing CPO activity is very simple and useful. It will be favorable to the practical application of this enzyme.     

Electrocatalytic Oxidation of Formaldehyde on Copper Oxide Nano-crystalline Modified Glassy Carbon Electrode

This research found a cheap and efficient catalyst for electrooxidation of formaldehyde (HCHO). A CuO nano‐crystalline modified glassy carbon electrode (GCE) was fabricated and had an excellent electrocatalytic activity towards the oxidation of HCHO. Both the effect of potential scan rate and the effect of HCHO concentration on the electrocatalytic oxidation performance of the electrode were investigated. The amperometric current response of the electrode was proportional to HCHO concentration in the range of 1.0 µmol·L^?1–10.0 mmol·L^?1 with a detection limit (s/n=3) of 0.25 µmol·L^?1. The electrode was stable, showing the CuO nano‐crystlline is promising for applications in fuel cells and electrochemical sensors.     

Effect of Pb2＋ on the Kinetic and Spectral Characterization of Ribulose-1,5-bisphosphate Carboxylase/Oxygenase

本文利用各种光谱手段在体外研究了各种浓度的Pb2+对菠菜Rubisco活性影响的机制。 结果表明,Rubisco活性随着Pb2+处理浓度的增加而逐渐下降,低浓度Pb2+下Rubisco的动力学常数和最大反应速率分别为1.74 µM 和 0.42 µmol CO2/mg protein∙min,高浓度Pb2+下Rubisco的动力学常数和最大反应速率分别为11.82 µM and 0.28 µmol CO2/mg protein∙min。光谱学分析证实Pb2+可直接结合到Rubisco上, 其结合位点数为1.1个,结合常数分别为8.63×104 和 2.18×105 L/mol。ICP-MS和圆二色谱分析证实Pb2+取代了酶活性中心的Mg2+ 并改变了酶的构象。     

Further New Cembrane Diterpenes from the Hainan Soft Coral Sarcophyton latum

Two new cembranoid diterpenes, diepoxysarcophytonene ( 1 ) and sarconphytonol ( 2 ), were isolated from the Hainan soft coral Sarcophyton latum. Their structures including relative stereochemistry were established by 1D and 2D NMR spectroscopic techniques. Compound 1 showed weak inhibitory activity against COX‐2 in vitro at the concentration of 10^?5 µmol·L^?1 with the inhibitory rate of 55%.     

A Highly Selective Colorimetric Sensor for Cu2+ Based on Phenolic Group Biscarbonyl Hydrazone

A novel copper selective sensor 2 based on hydrazide and salicylaldehyde has been designed and prepared. Sensor 2 behaves a single selectivity and sensitivity in the recognition for Cu²⁺ over other metal ions such as Fe³⁺, Hg²⁺, Ag⁺, Ca²⁺, Zn²⁺, Pb²⁺, Cd²⁺, Ni²⁺, Co²⁺, Cr³⁺ and Mg²⁺ in DMSO. The distinct color change and the rapid changement of fluorescence emission provide naked‐eyes detection for Cu²⁺. The UV‐vis data indicate that 1:2 stoichiometry complex is formed by sensor 2 and Cu²⁺. The association constant K_s was 3.51×10⁴ mol^?1·L. The detection limitation of Cu²⁺ with the sensor 2 was 2.2×10^?7 mol·L^?1. The sensing of Cu²⁺ by this sensor was found to be reversible, with the Cu²⁺‐induced color being lost upon addition of EDTA.     

Rapid Determination of Free Amino Acids in Milk by Microchip Electrophoresis Coupled with Laser‐induced Fluorescence Detection

A simple and sensitive method for determination of free amino acids in milk by microchip electrophoresis (MCE) coupled with laser‐induced fluorescence (LIF) detection was developed. Seven kinds of standard amino acids were derivated with sulfoindocyanine succinimidyl ester (Cy5) and then perfectly measured by MCE‐LIF within 150 s. The parameters of MCE separation were carefully investigated to obtain the optimal conditions: 100 mmol·L^?1 sodium borate solution (pH 10.0) as running buffer solution, 0.8 kV as injection voltage, 2.2 kV as separation voltage etc. The linear range of the detection of amino acids was from 0.01 µmol·L^?1 to 1.0 µmol·L^?1 and the detection limit was as low as about 1.0 nmol·L^?1. This MCE‐LIF method was applied to the measurements of free amino acids in actual milk samples and satisfactory experimental results were achieved.     

Effect of inorganic positive ions on the adsorption of surfactant Triton X-100 at quartz/solution interface

The electrode-separated piezoelectric sensor (ESPS), an improved setup of quartz crystal microbalance (QCM), has been employed to investigate the adsorption behavior of nonionic surfactant Triton X-100 at the hydrophilic quartz-solution interface in mineralized water medium in situ, which contained CaCl2 0.01 mol·L?1, MgCl2 0.01 mol·L?1, NaCl 0.35 mol·L?1. In a large scale of surfactant concentration, the effects of Ca2 , Mg2 and Na on the adsorption isotherm and kinetics are obviously different. In aque-ous solution containing NaCl only, adsorption of Triton X-100 on quartz-solution interface is promoted, both adsorption rate and adsorption amount increase. While in mineralized water medium, multivalent positive ions Ca2 and Mg2 are firmly adsorbed on quartz-solution interface, result in the increasing of adsorption rate and adsorption amount at low concentration of surfactant and the peculiar desorption of surfactant at high concentration of Triton X-100. The results got by solution depletion method are in good agreement with which obtained by ESPS. The "bridge" and "separate" effect of inorganic positive ions on the adsorption and desorption mechanism of Triton X-100 at the quartz- solution interface is discussed with molecular dynamics simulations (MD), flame atomic absorption spectrometry (FAAS) and atomic force microscopy (AFM) methods.     

Electrochemiluminescence of SDBS‐Ru(bpy)32+‐CPM System and Its Application

When the concentration of dodecyl benzene sulfonic acid sodium salt (SDBS) is 0.7 mmol·L^?1, the electrochemical and electrochemiluminescence (ECL) intensity of Ru(bpy)₃²⁺‐chlorpheniramine maleate (CPM) system at the Au electrode were studied. The results showed that compared with the absence of SDBS, enhancement of the ECL intensity was 14‐fold at Au electrode. Base on this, an ECL method was established for efficient and simple determination of CPM at Au electrode. Under the optimum experimental condition, the enhanced ECL intensities had good linear relationship with the concentration of CPM in the range of 1.0×10^?4–1.0×10^?7 mol·L^?1, and a linear regression equation was obtained as follows: I (counts)=48.805×10⁶c+394.03 (r=0.9975), the detection limit for CPM was 1.4×10^?8 mol·L^?1. The RSD for 5 times determinations of 1.0×10^?5 mol·L^?1 CPM was 3.2%. The results of recovery test were between 96.3%–102.5%, and the RSD of recovery test (n=5) was 2.7%. In addition, eleven kinds of tertiary amines‐Ru(bpy)₃²⁺ systems were investigated in the absence and presence of SDBS. The results showed that the enhancement of SDBS on ECL intensity of tertiary amines‐Ru(bpy)₃²⁺ systems was universal.     

Cu2+和Cu+对原代培养的小鼠成骨细胞增殖、分化和钙化的影响

利用噻唑蓝(MTT)法、碱性磷酸酶(ALP)比活性测定、油红O染色和矿化结节染色及定量分析,研究了Cu²⁺和Cu⁺对原代培养的成骨细胞增殖、分化及钙化的影响。结果显示：Cu²⁺(1×10^-9~1×10^-6 mol·L^-1)促进成骨细胞增殖,随时间延长,促进作用变弱。Cu⁺(1×10^-7~1×10^-5 mol·L^-1)抑制成骨细胞增殖,随时间延长,浓度为1×10^-6 mol·L^-1的Cu⁺为促进作用,其余浓度则没有影响。对于成骨细胞分化,Cu²⁺和Cu⁺表现出相似的影响,浓度为1×10^-9和1×10^-6 mol·L^-1时均促进成骨细胞分化,而当浓度为1×10^-7和1×10^-5 mol·L^-1时,则抑制成骨细胞分化,随作用时间延长,大多数浓度均表现为促进作用。测试浓度下的Cu²⁺和Cu⁺均对成骨细胞向脂肪细胞的横向分化表现为促进效应。对矿化功能的影响,1×10^-5 mol·L^-1的Cu²⁺和Cu⁺表现出显著的抑制效应,但随浓度降低,抑制效应变弱。1×10^-7 mol·L^-1的Cu²⁺ 促进成骨细胞矿化结节的形成。结果提示：作用浓度、作用时间及铜离子的价态都是影响Cu²⁺和Cu⁺生物效应转变(从毒性到活性,从损伤到保护,从下调到上调)的关键因素。     

Solid-phase extraction of Pb2+ ion from environmental samples onto L-AC-Ag-NP by flame atomic absorption spectrometry (FAAS)

The development of a solid-phase extraction (SPE) procedure for the pre-concentration of trace amounts of Pb²⁺ ion on 2-furan-2-yl-1-furan-2-ylmethyl-1H-benzoimidazole loaded on activated carbon modified with silver nanoparticles (L-AC-Ag-NP) was presented. The metal ion retained on the sorbent was quantitatively determined via complexation with the ligand. The complexed metal ion was efficiently eluted using 10 mL of 4 mol L^?1 sulphuric acid in 10 w/v% acetone. The influences of the analytical parameters, including pH, amounts of the ligand and the solid phase, eluent conditions and sample volume, on the recoveries of the metal ion were optimised. Using the optimised parameters, the linear response of the SPE method for Pb²⁺ ion were in the ranges of 0.2–160 µg L^?1, and the detection limit for Pb²⁺ ion was 0.034 µg L^?1. The proposed method exhibits a pre-concentration factor (PF) of 80 and an enhancement factor of 30 for Pb²⁺ ion. The presented results demonstrate the successful application of the proposed method for the determination of Pb²⁺ ion in some real samples with high recoveries (>93%) and reasonable relative standard deviation (RSD < 2%).