紫外-可见吸收光谱法研究细胞色素C活性中心铁离子与微量元素的相互作用

应用紫外－可见吸收光谱法研究细胞细色素C（Fecty-C)活性中心铁离子在pH7．1的磷酸缓冲液中与4种微量元素M（Ⅱ）的直接相互作用。结果表明,细胞色素C（Fecyt-C)活性中心Fe(Ⅱ）离子可被微量元素M（Ⅱ）部分取代,形成部分的细胞色素C衍生物（Mcyt-C),溶液的吸收光谱的Soret带最大吸收峰发生蓝移,且α带与β带最大吸收峰相对峰强减弱。     

细胞色素C与细胞色素氧化酶相互作用对细胞色素C共振拉曼谱和偏振特性的影响

细胞色素Ｃ与细胞色素氧化酶相互作用对细胞色素Ｃ共振拉曼谱和偏振特性的影响孙永泰，李迅，徐建兴（中国科学院生物物理研究所北京１００１０１）陈强，张明生（南京大学固体微结构国家开放实验室，南京大学分析测试中心南京２１０００８）ＩｎｆｌｕｅｎｃｅｏｆＩｎｔ...     

可见吸收光谱法研究铜锌超氧歧化酶活性中心金属离子与氯化钴的相互作用

应用可见吸收光谱首次研究了铜锌超氧歧化酶（Ｃｕ２Ｚｎ２ＳＯＤ）活性中心金属离子在一定缓冲溶液中与无机氯化钴的直接相互作用。讨论了加入不同比例量的氯化钴、不同的ｐＨ值、不同酸盐及作用的平衡时间对这种相互作用的影响。结果发现，ＣｏＣｌ２中的Ｃｏ（Ⅱ）与Ｃｕ２Ｚｎ２ＳＯＤ中的Ｚｎ（Ⅱ）有交换作用，形成部分的Ｃｕ２中的Ｃｏ２ＳＯＤ，且上述四种因素对此均有不同程度的影响。本研究开创了金属酶活性中心金属离子与外加无机金属化合物的直接相互作用的研究。     

小牛胸腺DNA与细胞色素C相互作用的电化学和光谱研究

利用电化学和紫外-可见(UV-Vis)反射吸收光谱技术研究了固定到带正电的尼龙膜上的小牛胸腺DNA(CT-DNA)与马心细胞色素C之间的相互作用,发现马心细胞色素C能以其带正电的活性区域一端吸附到带负电的CT-DNA表面,因此CT-DNA能促进马心细胞色素C的直接电化学反应。     

可见吸收光谱法研究铜锌超氧化歧化酶活性中心金属离子与氯…

应用可见吸收光谱首次研究了铜锌超氧化酶（Ｃｕ２Ｚｎ２ＳＯＤ）活性中心金属离子在一定缓冲溶液中与无机氯化钴的直接相互作用，讨论了加入不同比例量的氯化钴，不同的ｐＨ值，不同酸盐及作用的平衡时间对这种相互作用的影响，结果发现，ＣｏＣｌ２中的Ｃｏ（Ⅱ）与Ｃｕ２Ｚｎ２ＳＯＤ中的Ｚｎ（Ⅱ）有交换作用，形成部分的Ｃｕ２中的Ｃｏ２ＳＯＤ，且上述四种因素对此均有不同程度的影响，本研究开创了金属酶活性中心金属离子与外     

用同步荧光光谱法研究细胞色素C与胱氨酸的相互作用

用同步荧光技术研究了细胞色素Ｃ与促进剂胱氨酸的相互作用，分别监测了二者相互作用时细胞色素Ｃ中色氨酸残基和酪氨酸残基的荧光光谱的变化和二种氨基酸残基的荧光强度随的变化，实验结果表明，胱氨酸分子与细胞色素Ｃ的赖氨酸残基缓慢结合，二者相互作用的最终结果使细胞色素Ｃ分子的构象发生了微小的变化。     

光谱法研究铜锌超氧歧化酶与组氨酸钴(Ⅱ)的相互作用 Ⅱ.外加组氨酸钴(Ⅱ)及磷酸盐的影响

采用ＶＩＳ和 ＩＣＰ及酶活性测定等方法,研究铜锌超氧歧化酶（Ｃｕ２Ｚｎ２ＳＯＤ）与组氨酸钴（Ⅱ）［Ｃｏ（Ｈｉｓ）ｎ］ 的直接相互作用及外加组氨酸钴（Ⅱ）、磷酸盐对此类相互作用的影响。结果发现,水溶液中原酶活性中心的Ｃｕ（Ⅱ）和Ｚｎ（Ⅱ）离子可被外加的组氨酸钴（Ⅱ）部分诱导、交换出来,而Ｃｏ（Ｈｉｓ）ｎ 中的Ｃｏ（Ⅱ）进入酶的活性中心,形成“Ｃｏ－ＳＯＤ”酶衍生物各组分,并相应影响了酶的催化活性。与此同时,外加组氨酸钴（Ⅱ）及磷酸盐对此类相互作用有着重要的影响     

可见光谱法研究肌红蛋白血红素铁与金属离子相互作用(Ⅰ)

肌红蛋白(Myoglobin,Mb)是哺乳动物细胞主要是肌细胞贮存和分配氧的蛋白质, 由一条多肽链和一个血红素辅基构成,其血红素铁在氧气的传递和运输中起到关键作用。文章利用紫外-可见光谱法对肌红蛋白的血红素铁和外加金属离子M(Ⅱ)[Cu(Ⅱ), Zn(Ⅱ)和Co(Ⅱ)] 的直接相互作用进行了研究。结果发现, 金属离子M(Ⅱ)与肌红蛋白活性中心的Fe(Ⅱ)发生了直接相互作用,外加金属离子将铁离子从肌红蛋白中“拖拽”出来,形成部分空位肌红蛋白衍生物。同时研究了外界条件,如离子浓度对这种相互作用的影响,发现随着外加金属离子量的增加这种相互作用逐渐增强,其作用强度依次为Co(Ⅱ)＞Zn(Ⅱ)＞Cu(Ⅱ)。 研究证实了肌红蛋白的血红素铁与金属离子之间存在直接相互作用,并且离子浓度对这种相互作用有影响。     

光谱、波谱法研究铜锌超氧歧化酶与氯化钴(Ⅱ)、组氨酸钴(Ⅱ)相互作用

我们首次发现的铜锌超氧歧化酶（Ｃｕ２Ｚｎ２ＳＯＤ）与氨基酸等发生直接相互作用的现象,是一种前人未研究过的重要的生化新现象［１］。在此新发现的基础上,本文用ＩＣＰ,ＶＩＳ,ＮＭＲ和酶活性测定等方法,又从不同角度拓展研究了Ｃｕ２Ｚｎ２ＳＯＤ酶与两类不同化合物,即无机氯化钴（ＣｏＣｌ２）、有机组氨酸钴（Ｃｏ（Ⅱ）（Ｈｉｓ）ｎ）的直接相互作用,发现酶活性中心金属离子同样与外加的这两类不同化合物发生相互作用,相应地影响了酶的催化活性。还发现Ｃｏ（Ⅱ）（Ｈｉｓ）ｎ比ＣｏＣｌ２与酶相互作用更强、更快,Ｃｏ（Ⅱ）（Ｈｉｓ）ｎ中的Ｃｏ（Ⅱ）更易进入酶中,更影响了酶的催化活性。     

光谱法研究铜锌超氧歧化酶与组氨酸钴（Ⅱ）的相互作用：Ⅱ. …

采用ＶＩＳ和ＩＣＰ及酶活性测定等方法,研究铜锌超氧歧化酶（Ｃｕ２ＺｎＳＯＤ）与组氨酸钴（Ⅱ）〖Ｃｏ（Ｈｉｓ）〗的直接相互作用及外加组氨酸钴（Ⅱ）、磷酸盐对此类相互作用的影响。结果发现,水溶液中原酶活性中心Ｃｕ（Ⅱ）和Ｚｎ（Ⅱ）离子可被外加的组氨酸钴（Ⅱ）部分诱导,交换出来,而Ｃｏ（Ｈｉｓ）。中的Ｃｏ（Ⅱ）进入酶的活性中心,形成“Ｃｏ－ＳＯＤ”酶衍生物各组分,并相应影响了酶的催化活性。与此同时,外加     

The Cu(II)-nitroxyl radicals system: the high activity and reactivation of the catalyst in the decomposition of hydroperoxides

Chelate copper(II) compounds were shown to exhibit high catalytic activity in the decomposition of hydroperoxides in the presence of nitroxyl radicals. The participation of nitroxyl radicals as cocatalysts increased the rate of the reaction and the number of catalytic cycles. Nitroxyl radicals provided catalyst reactivation after complete activity loss characteristic of the process in the absence of promoting admixtures. The promoting action of nitroxyl radicals was observed for hydroperoxides and was not for diacylperoxides. The special behavior of the catalytic system with respect to hydroperoxides presupposed the participation of nitroxyl radicals in one of the key stages of proton transfer from the copper(II)…hydroperoxide complex in the overall reaction mechanism. We, however, did not observe direct interaction between nitroxyl radicals and copper(II) ions by the electron transfer mechanism.     

Synthesis,characterization, and thermo-mechanical properties of copper-loaded apatitic calcium phosphates

Copper is well known as a classical transition metal used in heterogeneous catalysis. In this study, copper-loaded apatitic calcium phosphates were prepared using incipient wetness impregnation (IWI) and ionic exchange (IE) methods. The interaction between copper precursor (copper nitrate trihydrate, Cu(NO₃)₂?3H₂O) and apatitic calcium phosphate (CaP) depended strongly on the preparation method and the content of copper-loaded. Using IE, copper(II) cations (Cu²⁺) were incorporated in the apatitic structure of CaP. The content of copper(II) cations seemed to be limited at about 2.2?wt.%. Calcination at 400?°C had no influence on the solids obtained by the IE method. Using IWI, the deposition of a theoretical copper content of 2?wt.% led to the incorporation of copper(II) cations in the apatitic structure of CaP by IE with Ca²⁺, despite the low quantity of aqueous solvent used. Therefore the resulting product was similar to that obtained by IE. When the theoretical copper content rose to 20?wt.%, the entire amount of copper precursor molecules were largely deposited, which resulted in the formation of copper oxide particles (CuO) after air calcination at 400?°C. Thermo-mechanical analysis study showed that the presence of copper oxide did not modify the thermal shrinkage of the initial calcium phosphate. On the other hand, thermal shrinkage was much more important in the case of CaP substituted with copper(II) cations.     

Selectivity in metal ions mediated C–N bond formation reactions of 8‐aminoquinoline derivatives

Cyclisation reactions via C–N bond formation of 2‐bromo‐N‐(quinolin‐8‐yl)propanamide (I) and 2‐bromo‐N‐(quinolin‐8‐yl)acetamide (II) are facilitated by metal salts such as copper (+2), nickel (+2) perchlorate or nitrate and palladium (+2) acetate. Nickel (+2) perchlorate mediated reaction of I and II resulted in C–N bond formation to give corresponding perchlorate salts of three fused six‐membered heterocyclic rings. The copper (+2) mediated reactions are found to be solvent dependent for I, but independent for II. Copper mediated reaction of II gave cyclised product analogous to the one obtained from reaction of II with nickel (+2) perchlorate in methanol or ethanol. But the reaction of I with copper (+2) perchlorate in methanol gave C–N bonded methoxylated cyclised product. This reaction took place in two steps, cyclisation followed by methoxylation. The source of methoxy group is confirmed to be from methanol by deuterium labelling experiments. Whereas similar copper mediated reaction of I in ethanol led to nucleophilic substitution of bromide ion by ethoxide. The structures of the salts of fused heterocyclic compounds were determined and their fluorescence emissions were studied. The large difference in fluorescence emission of compound V formed from copper mediated reaction in ethanol from the compound VI formed from nickel mediated reaction in methanol or ethanol, this feature can be used to distinguish nickel (+2) and copper (+2) ions. The reaction of II with palladium (+2) acetate resulted in the formation of C–N bond to yield the corresponding heterocycle as bromide salt; without anion exchange. Copyright © 2011 John Wiley & Sons, Ltd.     

Effect of the Protonation and Chemical Doping of Poly(o-toludine) with Copper Sulfate on the Spectral and Electrical Properties of the Host Polymer

Poly(o-toluidine) (POT) and its samples doped with copper sulfate, a transition metal salt, were synthesized by a chemical oxidative polymerization technique using potassium dichromate as oxidant in aqueous hydrochloric acid medium and chemical doping with copper sulfate. The prepared polymeric samples were characterized by ultraviolet (UV)-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, and DC conductivity measurement techniques. The UV-visible spectra of doped polymer displayed peaks indicating the presence of charged particles/polarons and/or formation of conducting POT. The characteristic FTIR peaks of the doped polymer provided information regarding structural changes in the backbone of POT and were consistent with the interaction of the benzenoid groups of the polymer with metal ions. X-ray diffraction patterns of powdered doped polymer showed an amorphous nature, as exhibited by most conducting polymers. The DC conductivity of doped polymer was measured by a two-probe method in the temperature range of 300–400 K; a significant enhancement in DC conductivity was observed with an increase in temperature, showing the semiconductor nature of the synthesized doped polymer.     

Influence of activated carbon surface acidity on adsorption of heavy metal ions and aromatics from aqueous solution

Adsorption of toxic heavy metal ions and aromatic compounds onto activated carbons of various amount of surface C-O complexes were examined to study the optimum surface conditions for adsorption in aqueous phase. Cadmium(II) and zinc(II) were used as heavy metal ions, and phenol and nitrobenzene as aromatic compounds, respectively. Activated carbon was de-ashed followed by oxidation with nitric acid, and then it was stepwise out-gassed in helium flow up to 1273 K to gradually remove C-O complexes introduced by the oxidation. The oxidized activated carbon exhibited superior adsorption for heavy metal ions but poor performance for aromatic compounds. Both heavy metal ions and aromatics can be removed to much extent by the out-gassed activated carbon at 1273 K. Removing C-O complexes, the adsorption mechanisms would be switched from ion exchange to Cπ-cation interaction for the heavy metals adsorption, and from some kind of oxygen-aromatics interaction to π-π dispersion for the aromatics.     

A Structural Study of Some Metal Diethyldithiocarbamate Chelates by X-ray Photoelectron Spectroscopy

The diethyldithiocarbamate chelates of copper (II), lead (II) and tin (IV) have been prepared and characterized. Pure or nearly pure metal diethyldithiocarbamate (DEDTC) chelates could be prepared through recrystallization. The x-ray photoelectron spectra (XPS) for the recrystallized samples were obtained. Three different carbons (C Is) in the diethyldithiocarbamate molecule can be recognized through a computer deconvolution system. Sulfer 2p showed two peaks of spin doublet S 2p_1/2 and S 2p_3/2. Based on the XPS results we may conclude that the diethyldithiocarbamate ligand forms an unusual 4-membered chelate ring structure with the metal ion, both sulfur having bonding with the metal. The N in the DEDTC may also bind with the metal.