PAP-H2O2-HRP酶促反应产物光谱及电化学研究

前文［１］首次提出了以对氨基酚（ＰＡＰ）为底物的ＰＡＰ－Ｈ２Ｏ２－辣根过氧化物酶（ＨＲＰ）伏安酶联免疫分析新体系,并成功地应用于烟草花叶等植物病毒的血清学检测．在此之前,我们也曾报道过一些伏安酶联免疫分析新体系［２,３］．迄今,还没有人对 ＨＲＰ催化 Ｈ２Ｏ２氧化 ＰＡＰ的酶促反应进行过探讨．Ｐｒａｔｉ等［４］报道了在铜催化作用下,Ｏ２氧化对氨基酚生成３－［（４－个羟苯基）氨基」－４－（２－氨基－５－羟苯基）－６－［（４－羟苯基）亚胺基］－２,４－环己二烯基－１－酮．本文的实验结果与此文献不符． 为…     

H2O2—H2SO4体系电化学振荡行为的研究

Ｈ２Ｏ２参与的电化学振荡反应长期以来倍受人们的关注［１,２,３］,文献［１］报道了Ａｇ电极在Ｈ２Ｏ２－ＨＣｌＯ４水溶液中的电势振荡现象;文献［２］报道了Ｐｔ电极Ｈ２Ｏ２－Ｈ２ＳＯ４体系在控电流条件下的电势振荡,其实验的Ｈ２Ｏ２浓度范围为０．０２～０．...     

以交联聚丙烯酸甲酯为载体的多乙烯多胺／铜（Ⅱ）络合物的合成及其对尿素的吸附性

以大孔交联聚丙烯酸甲酯为原料，引入多乙烯多胺［Ｈ（ＮＨＣＨ２ＣＨ２）ｎＮＨ２，ｎ＝２，３，４］配体，络合二价铜离子，合成出一系列以交联聚内烯酸甲酯为载体的多乙烯多胺／铜（Ⅱ）络合物，研究了这类高分子络合物在不同条件下对尿素的吸附性能。结果说明，在载体树脂相同时．配体不同的络合物树脂对尿素的吸附性能有很大差异，以二乙烯三胺或三乙烯四胺为配体，产物树脂对尿素的吸附量较大，而以四乙烯五胺为配体则吸附量较小。在尿素浓度１３０ｍｇ／ｄｌ、吸附时间８小时、介质为ｐＨ＝７的Ｎａ２ＨＰＯ４－ＮａＨ２ＰＯ４缓冲溶液、温度１８℃时，该类高分子络合物对尿素的最大吸附量达到７５．２ｍｇ／ｇ。     

葡萄糖氧化酶电极的制备

葡萄糖氧化酶电极的制备于秀娟，周定，郭京华（哈尔滨工业大学应用化学系哈尔滨１５０００６）关键词葡萄糖氢化酶，酶电极，制备酶与电极的连接即酶膜的形成是制备酶电极的关键步骤之一，有许多种方式［１～９］．葡萄糖氧化酶（ＧＯＤ）电极是研究较早和报道较多的一类...     

4-[2-(4-N,N-二甲基苯胺基)乙烯基]吡啶氧化物的电化学行为

半菁染料是人们制造ＬＢ膜的材料之一．近年来,为得到电导率较高的薄膜,电荷转移络合物的ＬＢ膜受到重视［１］．实验证明,有机材料的ＬＢ膜经化学修饰或改性以后,电导率大大增加．化学工作者常将有机染料分子用来修饰电极,在光电化学、电催化等方面有较好的效果,因而,受到人们极大的关注．化学工作者已成功地制备出许多染料化学修饰电极,研究膜修饰电极的电化学行为［２,３］,而用循环伏安法和光谱技术对有机染料的电化学行为研究得较少［４,５］．本文对４ ［２ (４ Ｎ,Ｎ 二甲基苯胺基 )乙烯基］吡啶氧化物这个新改性的半菁化…     

基于Fe3O4 纳米颗粒修饰膜固定尿素酶与谷脱氢酶的尿素传感器

将Fe3O4纳米粒子吸附于涂有壳聚糖(CH)膜的铟锡氧化物导电玻璃(ITO)上,获得Fe3O4纳米粒子-壳聚糖膜修饰电极,再将脲酶(Ur)和谷氨酸脱氢酶(GLDH)通过静电吸附固定在复合物膜上制备了尿素传感器.运用红外光谱、电子显微镜对传感膜的结构进行了表征;以制备的双酶电极为工作电极,采用微分脉冲伏安法研究了酶电极对尿素的响应,结果表明Ur-GLDH/CH-Fe3O4/ITO生物电极的峰电流对尿素非常敏感,尿素的质量浓度与峰电流分别在5 ～40 mg/L和60 ～100 mg/L范围内呈线性相关,检出限为0.5 mg/L .固定酶的米氏常数Km为0.56 mmol/L,该值较小,表明混合酶(Ur-GLDH)和尿素具有较好的亲和性.在CH-Fe3O4膜中,Fe3O4纳米粒子的引入增加了壳聚糖膜的表面积,增强了电极的电子传递;CH具有生物相容性,有利于保持生物酶活性.     

燃料电池电极制作方法的研究

对燃料电池,性能良好的催化剂至关重要,它决定着大电流密度放电时的性能、成本和运行寿命［１］．但因电极上的反应是气、液、固三相反应,所以必须制备出高效的、结构合理的气体电极［２～３］,减小气相、液相传质阻力,提高三相接触性能,降低电极极化．Ｋ．Ｍｕｎｄ等［４～５］所制作的电极,气体扩散距离长,溶解气体的扩散电阻大．Ｒ．Ｐ．Ｉｃｚｋｏｗｓｋｉ等人［６］用ＰＴＦＥ（ｐｏｌｙｔｅｔｒａｆｌｕｏｒｏｅｔｈｙｌｅｎｅ,聚四氟乙烯）作疏水剂,在整个气体反应层制成气体扩散通道,改善了电极性能．后来,Ｓ．Ｍｏｔ…     

用尖晶石型化合物NiCo2O4和复合镀技术制备析氧电极

为减少析氧电位、提高电极的稳定性、降低能耗和成本，人们一直在努力合成各种过渡金属复合氧化物作为析氧的电催化材料［１］．研究表明，尖晶石型化合物ＮｉＣｏ２Ｏ４对氧的析出有较高的催化活性［２］．但因其制备方法多为喷涂热解法，需４００℃以上温度，因此易发生...     

核糖核酸酶在DAB-环已烷反胶束溶液中的活性

表面活性剂在有机溶剂中形成的反胶束可以增溶大量的水分子，很多水溶性的物质又可溶解在反胶束的核心水团当中，这些都已是不争的事实［1］．酶在反胶束中的溶解对蛋白质的萃取分离，生物合成等方面有着十分广阔的应用前景，已引起了广泛的注意，文献逐年增加［2－4］．核糖核酸酶A（RNaseA）分子量较小，性质稳定，活性的测定简便易行，很适于作为反胶束－酶体系的研究对象，但大部分研究集中在阴离子表面活性剂AerosolT（AOT）的反胶束体系上，而对其它表面活性剂反胶束－酶体系的研究很少［5，6］．Papadimitriou等曾发现．糜蛋白酶…     

一种简易的尿素酶pH电极

酶电极最初以制备测定葡萄糖的电极而取名。只要将一层固定化酶膜包在特殊的离子选择性电极外面,就作成了酶电极。近年已制备了测定多种化合物的酶电极,将有可能在工业、临床、环境监测分析中得到广泛应用。尿素是肾、肝功能的重要指标。故曾有人制备了以铵离子选择性电极和CO_2选择性电极为基础的尿素酶电极用于测定尿素,但受到K~+、Na~+离子的干扰,后来又制备出只对NH_3     

Enzyme engineering

Enzyme research and development efforts have been shaped by the tools and concepts available for enzyme production and utilization. A new phase of enzymology characterized by the production of modified protein catalysts has begun, made possible by recombinant DNA technology.     

Enzyme mimics

Chemists are trying to create synthetic molecules which mimic the recognition and catalytic properties of real enzymes. One target of interest is catalysis of reactions for which there are no known natural enzymes. Inspired by the examples of nature, approaches to the design of enzyme mimics for catalysis of Diels-Alder reaction are described. The design is based on porphyrin molecular boxes and zinc co-ordination. The potential of design of enzyme mimics employing cholic acid and other systems is also discussed.     

丝素膜固定化丝网印刷酶电极

采用丝网印刷技术制作的一次性薄层碳电极具有良好的分析性能。经化学修饰二茂铁后,以丝素为固定化载体固定含有多酚氧化酶的蘑菇萃取蛋白,所得酸电极对其底物邻苯二酚和多巴胺有良好响应,线性范围为２．０×１０－８～２．０×１０－２,ｍｏｌ／Ｌ,在３０ｓ内即可达到９５％稳态电流。该电极的ＲＳＤ为２．７％,且可保持１０天以上的工作寿命。该酶电极在低温湿润环境中可保存较长时间,因此有较好的商品化前景。     

Stabilization of the Cellulase Enzyme Complex as Enzyme Nanoparticle

The native Celluclast BG cellulase enzyme complex consists of different enzymes which can also degrade great substrate molecules as native celluloses. This enzyme complex has been covered by a very thin, a few nanometers thick, polymer layer, in order to improve its stability. It has been proved that the polymer layer around the enzyme molecules does not hinder the digestion as great substrates as crystalline cellulose polymer. The stability of the prepared enzyme nanoparticles (PE) could significantly be increased comparing to that of the native one what was proved by results of the total cellulose activity measured. The pretreated enzyme complex holds its activity often a few magnitudes of orders longer in time than that of the native enzyme complex (enzyme without pretreatment). It retains its activity at least ten times longer than that of the native one, at a temperature range between 20 and 37?°C. The pretreated enzyme complex can have about 50?% of its original activity during 12?h of incubation at even 80?°C, while the native cellulase one totally lost it during 6?h incubation time. The activity of PE has not been significantly reduced even at extreme pH values, namely in the pH range of 1.5 to 12.     

Amperometric Enzyme Sensor-Based Enzyme Immunoassay for Factor VIII-Related Antigen

Abstract

The coupling of an enzyme immunoassay for factor VIII-related antigen with a commercial glucose oxidase based amperometric sensor permits the determination of 1.6 to 16 ng of factor XIII-related antigen in human plasma. Further pure amperometric sensors or amperometric enzyme sensors for determination of the main marker-enzymes of enzyme immunoassays are described.     

On a New Enzyme Transducer Combination: The Enzyme Transistor

Abstract

The application of a hydrogen- and ammonia-sensitive, palladium-coated semiconductor device (Pd-MOSFET) in enzymic analysis has been studied. The response of the device to NH₃ liberated both non-enzymically as well as by the enzymes urease from urea and creatinine deiminase from creatinine was investigated. In the latter case, a flow-cell was used and the analysis was continuous. The device described, a kind of enzyme-transistor, is of relatively simple design.     

Artificial Enzyme Mimics for Catalysis and Double Natural Enzyme Co-immobilization

This work presents a new chemiluminescent (CL) probe array assay. The new type CL probe array is based on enzyme mimics of Co₃O₄–SiO₂ mesoporous nanocomposite material, which not only have an excellent catalytic effect on the luminol–H₂O₂ CL reaction in an alkaline medium but also can be used for the immobilization of enzymes. The linear range of the lactose concentration is 3.0?×?10^?7 to 1.0?×?10^?5 g mL^?1 and the detection limit is 6.9?×?10^?8 g mL^?1. β-Galactosidase and glucose oxidase were selected as a model for enzyme assays to demonstrate the applicability of Co₃O₄–SiO₂ mesoporous nanocomposite material in multienzyme immobilization. The novel bifunctional CL probe array has been successfully applied to the determination of lactose in milk.     

Computational Enzyme Design

Recent developments in computational chemistry and biology have come together in the “inside‐out” approach to enzyme engineering. Proteins have been designed to catalyze reactions not previously accelerated in nature. Some of these proteins fold and act as catalysts, but the success rate is still low. The achievements and limitations of the current technology are highlighted and contrasted to other protein engineering techniques. On its own, computational “inside‐out” design can lead to the production of catalytically active and selective proteins, but their kinetic performances fall short of natural enzymes. When combined with directed evolution, molecular dynamics simulations, and crowd‐sourced structure‐prediction approaches, however, computational designs can be significantly improved in terms of binding, turnover, and thermal stability.