谷胱甘肽过氧化物酶模拟物碲化透明质酸的合成及催化动力学研究

以透明质酸(HA)作为谷胱甘肽过氧化物酶(GPX)的酶模型,将碲(Te)引入HA中,合成了一种新型的高活力的GPX模拟物碲化透明质酸(TeHA).用红外光谱和核磁共振技术对TeHA的结构进行了研究,证明Te的修饰位点位于HA的N-乙酰氨基葡萄糖的羟甲基(-CH2OH)上.采用Wilson辅酶偶联法测定得到TeHA催化还原型谷胱甘肽(GSH)还原H2O2的GPX活力为163.6 U/μmol,高于文献报道的其它模拟酶.TeHA还能够催化GSH还原异丙苯基过氧化物(CuOOH)和叔丁基过氧化物(t-BuOOH)的反应,并且CuOOH为该模拟酶的最适底物.通过研究TeHA催化GSH还原三种不同过氧化物的反应动力学发现,TeHA的催化遵循乒乓机制.

Synthesis and kinetics of a novel mimic with glutathione peroxidase activity - Tellurium-containing hyaluronic acid (TeHA)

A novel mimic was synthesized by modifying hyaluronic acid (HA) with tellurium, whose function is similar to that of glutathione peroxidase (GPX). The structure of TeHA was characterized by means of IR and NMR, the target-Te was located at -CH2OH of the N-acetyl-D-glucosamine of HA. The H2O2 reducing activity of TeHA, by glutathione (GSH), was 163.6 U/mu mol according to Wilson's method. In contrast to other mimics, TeHA displayed the highest activity. Moreover, TeHA accepted many hydroperoxides as its substrates, such as H2O2, cumenyl hydroperoxide (CuOOH) and tert-butyl hydroperoxide (t-BuOOH), and CuOOH was the optimal substrate of TeHA. A ping-pong mechanism was observed in the steady-state kinetic studies of the reactions catalyzed by TeHA.

LB films of 2-n-heptadecanoylbenzoic-rare earth and their luminescence properties

Several ultrathin luminescent Langmuir-Blodgett (LB) films have been prepared by using the subphase containing the rare earth ions (Eu3+, Tb3-). The effect of the rare earth ions on the monolayer of 2-n-heptadecanoylbenzoic acid (HBA) was investigated. IR and UV spectra showed the rare earth ions were bound to the carboxylic acid head groups and the coordination took place between the polar head group and the rare earth ions. The layer structure of the LB films was demonstrated by low-angle X-ray diffraction. UV absorbance intensity increases linearly with the number of LB films layers, which indicate that the LB films are homogeneously deposited. The LB films can give off strong fluorescence. and the signal can be detected from a single layer. The characteristic luminescence behaviors of LB films have been discussed compared with those of the complexes.

Application of ionic liquids in organic reactions

Room-temperature ionic liquids are good solvents for a wide of organic, inorganic and organometallic compounds. Typically consisting of nitrogen-containing organic cations and inorganic anions, they are easy to recycle, nonflammable, and have no detectable vapor pressure. More recently, ionic liquids have been found to be excellent solvents for a number of chemical reactions, e. g. hydrogenation, alkylation, epoxidation, Heck-vinylation, Suzuki cross-coupling reactions and enzyme catalyzed organic reactions. This paper focuses on the recent development of using ionic liquids as solvents for transition metal and enzyme catalyzed reactions.

白山草乌中二萜生物碱的电喷雾串联质谱分析

利用电喷雾串联质谱 ( ESI-MS2 )对吉林省白山市地产草乌的乙醇提取液进行了直接分析 ,方法简便 ,直观 ,用样量少。ESI-MS可以给出分子量信息 ,MS2 方法则可以从复杂体系中获得结构信息。在该植物中发现中乌头碱、次乌头碱乌头碱及中乌头碱的水解产物和脂类生物碱等九种二萜生物碱

结构解析专家系统(ESESOC)中的两种自同构群算法

从图论的观点出发,在全通道拓扑等价性算法的基础上,进行了自同构群的生成研究,通过组合算法和将非环化合物转化为树的方法,分别对自同构群的生成算法进行了改进,并且应用于ESESOC系统的立体异构体的穷举生成过程中,取得了良好的结果。

离子液体在有机反应中的应用

室温离子液体 ,由含氮的有机阳离子和无机阴离子组成 ,可溶解各种有机、无机、金属有机化合物 .它们没有蒸气压、不易燃、容易循环使用 .近年已发现 ,离子液体可广泛地用于许多过渡金属化合物和酶催化的反应 .着重讨论这方面的发展状况

Further study on double-melting endotherms of isotactic polypropylene

The origins of the single- and double-melting endotherms of isotactic polypropylene crystallized at different temperatures were studied carefully by differential scanning calorimetry, wide-angle X-ray diffraction, and small-angle X-ray scattering. The experimental data show that spontaneous crystallization occurs when the crystallization temperature is lower than 117 degrees C; thus the lamellae formed are imperfect. At a lower heating rate, the recrystallization or reorganization of these imperfect lamellae leads to double endotherms. On the other hand, when the crystallization temperature is higher than 136 degrees C, two major kinds of lamellae with different thickness are developed during the isothermal process, which also results in the double-melting endotherms. In the intermediate temperature range the lamellae formed are perfect, and there is only a single peak in the distribution of lamellar thickness. This explains the origin of the single-melting endotherm. (C) 2000 John Wiley & Sons, Inc.

不对称三邻菲咯啉钌(Ⅱ)配合物的合成、电化学和荧光光谱(Ⅱ)

设计并合成了一种新化合物 5 -(3 -溴丙酰 )胺 -1 ,1 0 -邻菲咯啉 ,phen-NHCOCH2 CH2 Br(a) ,和一种新型电化学发光 (ECL)传感器活性材料 Ru(phen) 2 [phen-NHCOCH2 CH2 Br](PF6 ) 2 (b) ,利用元素分析、红外光谱、核磁共振氢谱和激光解析电离飞行时间质谱确证了其组成和结构。同时 ,还研究了化合物 b的荧光光谱和电化学行为。

Sol-gel synthesis and electrical properties of ceria-based solid electrolytes

A series of solid electrolytes (Ce0.8RE0.2)(1-x)MxO2-delta(RE: Rare earth, M: Alkali earth) were prepared by sol-gel methods. XRD indicated that a pure fluorite phase was formed at 800 degrees C. The synthesis temperature by the sol-gel methods was about 700 degrees C lower than by the traditional ceramic method. The electrical conductivity and impedance spectra were measured. XPS showed that the oxygen vacancy increased obviously by doping MO, thus, resulting in the increase of the oxygen ionic transport number and conductivity. The performance of ceria-based solid electrolyte was improved. The effects of RE2O3 and MO on the electrical properties were discussed. The conductivity and the oxygen ionic transport number of (Ce0.8Sm0.2)(1-0.05)Ca0.05O2-delta is 0.126 S.cm(-1) and 0.99 at 800 degrees C, respectively.

Ion-conducting polymers based on modified alternating maleic anhydride copolymer with oligo(oxyethylene) side chains

Comb-like polymers (CPs) based on modified alternating methyl vinyl ether/maleic anhydride copolymer with oligo(oxyethylene) side chains of the type -O(CH2CH2O)(n)CH3 were synthesized and characterized, and complexed with lithium salts to form amorphous polymer electrolytes. Maximum conductivity close to 1.38 x 10(-4) S/cm was achieved at room temperature and at a [Li]/[EO] ratio (EO = ethylene oxide) of about 0.066. The temperature dependence of ionic conductivity suggested that the ion transport was controlled by segmental motion of the polymer, shown by linear curves obtained in Vogel-Tammann-Fulcher plots. The ionic conductivity maximum moved to a higher salt concentration as the temperature increased, indicating that a larger number of charge carriers can be transferred through polymer chains, of which free volume is increased at higher temperature. IR results indicated that the ester in CPs might decompose at 140 degrees C and reproduce the maleic anhydride ring.

羟乙芦丁在玻碳电极上的阳极微分脉冲伏安法测定

本文对羟乙芦丁在玻碳电极上的阳极微分脉冲伏安行为进行了研究，发现在Na2HPO4溶液中（pH=8.95），于＋0.64V（vs．Ag／AgCl）左右产生一个良好的阳极氧化伏安峰，浓度在5～60mg／L之间与峰电流呈线性关系。不需分离直接测定了片剂中的羟乙芦丁含量。电极反应为扩散速率控制的不可逆可程。

PHYSICAL AGING OF HIGH-PERFORMANCE THERMOPLASTICS - ENTHALPY RELAXATION IN PEK-C AND PES-C

The developments of physical aging in phenolphthalein poly(aryl-ether-ketone) (PEK-C) and poly(aryl-ether-sulfone) (PES-C) with time at two aging temperatures up to 20 K below their respective glass transition temperatures (T-g = 495 and 520 K) have been studied using differential scanning calorimetry (DSC). Substantial relaxation within the aging course of several hours were observed by detecting T-g decreasing during physical aging process at the two aging temperatures. The relaxation processes of both polymers are extremely nonlinear and self-retarding. The time dependencies of their enthalpies during the initial stages of annealing were approximately modeled using the Narayanaswamy-Tool model. The structure relaxation parameters obtained from this fitting were used to predict the possibility of physical aging occurring at their respective using temperatures. (C) 1995 John Wiley and Sons, Inc.

ELECTROCHEMICAL CONTROLLED-RELEASE OF ADENOSINE-TRIPHOSPHATE

Polypyrrole (PPy) film was synthesized by anodic polymerization of pyrrole onto the surface of platinum electrode in the solution of sodium p-toluene sulfonate (NaTsO). When this film was oxidized anodically in an aqueous solution of adenosine triphosphatle (ATP), the ATP anions were incorporated into the film. Release of ATP From the film could be accomplished by reduction of the film in aqueous electrolyte solution. The total amount of ATP released from the film was determined by UV spectroscopic method.

MACROMOLECULAR COMPLEX OF POLYANILINE WITH SULFONATED POLYSTYRENE

The macromolecular complex of polyaniline(PAn) was prepared using sulfonated polystyrene(SPS) with sulfonation degree (SD) from 5 to 60mol% and characterized.