过氧化物酶催化去除水体中酚类内分泌干扰物的研究进展

内分泌干扰物(EDCs)会干扰生物体的内分泌系统从而对人类、野生动物以及水生生物产生负面影响,这一问题已经引起了人们的广泛关注.广泛分布于自然环境中的辣根过氧化物酶(HRP)和木质素过氧化物酶(LiP),具有较强的催化氧化能力,能够催化去除雌激素、双酚A等多种具有内分泌干扰效应的污染物.本文在介绍辣根过氧化物酶(HRP)和木质素过氧化物酶(LiP)两种过氧化物酶的相关性质和催化氧化机理的基础上,从污染物结构与其催化去除效率关系的角度综述了过氧化物酶去除具有内分泌干扰效应的污染物的研究进展.为污水处理过程中过氧化物酶用于去除内分泌干扰物提供依据,并展望了其未来的发展方向.     

纳米金属氧化物模拟天然酶催化水体中酚类污染物转化的研究进展

天然酶作为一种绿色催化剂,能够介导水体中酚类污染物形成酚氧自由基中间体,随后这些活性中间体通过共价偶联机制生成大分子聚合产物.纳米金属氧化物(N-MOs)兼具纳米材料和天然酶"双重身份",有望克服天然酶稳定性差、难回收、易失活和价格昂贵等缺点,高效地催化氧化水体中酚类污染物的转化.本文概述了两种天然酶(过氧化物酶和酚氧化酶)的基本性能及其催化偶联酚类污染物转化的作用机理,系统地探讨了N-MOs的纳米特性及其模拟天然酶催化氧化底物的显色反应、作用效能和影响因素,并阐释了N-MOs作为纳米酶催化氧化酚类污染物转化的最新研究进展及其潜在的应用价值,旨在为拓展和开发新型、有效地纳米酶在环境中的应用提供新的理论基础和技术指导.     

苏云金芽胞杆菌(Bacillus thuringiensis)几丁质酶的分离纯化及酶学性质

以苏云金芽胞杆菌为材料 ,通过硫酸铵沉淀分级分离、DEAE - 32离子交换柱层析初步纯化 ,获得比活力为15 0 .5Umg-1的酶制剂 .研究酶催化胶体几丁质水解的反应时间和酶量对酶活力的关系 ,探讨酶催化胶体几丁质的最适条件 .温度和 pH对酶活力的影响和酶的热稳定性及酸碱稳定性的结果表明 :酶催化胶体几丁质水解的的最适pH为 5 .6、最适温度为 5 8℃ .该酶在pH 4 .5～ 6 .5区域稳定 ,而在pH >8能很快失活 ;在 5 5℃以下处理 30min ,酶活力保持不变 ;高于 5 5℃ ,酶快速失活 .图 5参 11     

提高天冬氨酸β-脱羧酶在酸性环境中催化活力的分子改造

克隆了德阿昆哈假单胞菌(Pseudomonas dacunhae)来源的L-天冬氨酸β-脱羧酶基因(Asd),实现其在Escherichiacoli中的异源表达,但该酶在酸性环境中活性较低,不利于工业生产.为通过定点突变技术提高该酶在酸性环境中的活力,选择底物通道区域内的5个氨基酸残基作为突变位点,构建6个突变体,随后分析突变体的酶学特性.结果表明,相比于野生型Asd,大多数突变体的比酶活显著下降,只有突变体N34D比酶活(71.67 U/mg)比野生型(65.95 U/mg)略高;另外,突变体N34D在3.5 pH 5.5酸性环境中的酶活力与野生型Asd相比均得到了提高,其中pH5.0条件下突变体N34D相对酶活达到82%,而野生型Asd相对酶活只有50%左右;而在pH 5.5-8.5范围内突变体N34D的酶活力与野生型相当.最后将突变体N34D应用于催化合成L-丙氨酸,在最适催化条件(pH 5.5)下,突变体N34D催化合成L-丙氨酸的产量是野生型Asd的1.5倍.本研究通过对德阿昆哈假单胞菌来源的N34位点进行突变,成功提高了天冬氨酸β-脱羧酶在酸性环境中的酶活力,并提高了其合成L-丙氨酸的能力,这对酶法生产L-丙氨酸具有重要的指导意义.     

生物催化不对称还原制备(R)-1-[3,5-二(三氟甲基)苯基]乙醇研究进展

(R)-1-[3,5-二(三氟甲基)苯基]乙醇是合成药物阿瑞匹坦的关键中间体.以羰基还原酶生物催化前手性酮3,5-二(三氟甲基)苯乙酮的方法制备该中间体具有立体选择性优异、反应条件温和、对环境友好等优点,近年来受到广泛关注,目前已报道的高立体选择性酶源(产物ee 99%)有10余种.其中原始菌株生物催化体系能够转化底物的浓度普遍低于200 mmol/L,而利用重组Escherichia coli全细胞或者粗酶液则可催化1 mol/L以上的底物.通过添加离子液体、深共熔溶剂等辅溶剂,羰基还原酶与葡萄糖脱氢酶融合表达以及酶固定化技术等方法优化反应体系可以有效提高底物转化效率.有些羰基还原酶,如LXCAR、KR01、Ch KRED20等,能够催化异丙醇脱氢实现辅酶自循环,其催化体系具有明显优势.未来利用蛋白质工程技术对野生型的潜力酶进行人工进化,可以进一步提高利于工业应用的酶学性能,同时稳定的生产工艺、规模放大、后处理等方面也需要深入开展研究.(图2表3参52)     

有机废弃物降解过程酶作用及其调控机制的研究进展

有机废弃物处置不当造成的环境污染和资源浪费已引起广泛关注,生物降解可以有效地实现有机废弃物资源化利用。微生物分泌的酶能催化生物降解的矿化和腐殖化过程,提高有机物降解率。然而,以往研究主要集中于微生物作用,对有机废弃物降解过程酶作用及其调控机制的总结很少。该文从酶学和生物化学角度出发,论述了生物酶催化降解有机质、促进腐殖质合成和削减污染物毒性等作用过程。基于酶动力学和热力学特征,从微生物、酶的固定化、理化因子和添加剂4个方面阐述酶作用的调控机制。生物酶高效、环保、可控,是有机废弃物资源化利用的重要催化剂之一。未来应加强研究酶降解的途径与分子机制、微生物-酶-有机废弃物系统的新陈代谢、激活剂对酶作用的调控、酶的固定化技术以及降解酶的生产与应用,以推动有机废弃物资源化利用的进程。     

冰川环境耐冷菌的冷适蛋白酶分离纯化及酶学性质

采用离交和凝胶层析对“中国冰川1号”耐冷菌BacilluscereusSYPA23所产的蛋白酶进行分离纯化,并进行酶学性质研究.与中温酶相比,该蛋白酶具有较高的低温催化活力,其最适催化温度为42℃,适宜pH为7.0～8.5,SDSPAGE测定的分子量(Mr)为34.2×103.金属离子Mn2 、Ca2 对该酶有激活作用,Cu2 、Hg2 、Pb2 、Co2 对其活性有一定抑制作用.该酶属金属蛋白酶,其活性受EDTA强烈抑制,不受PMSF抑制.该蛋白酶具有低温酶典型的热不稳定性,0℃下半衰期24h,但Ca2 和一些低分子醇类物质能提高其稳定性.动力学数据分析表明,该蛋白酶在低温下对底物亲和能力高,在较宽温度范围内(25～45℃)均保持着较高的催化效能.图7表3参17     

粘质沙雷氏菌酶促过氧化氢降解对氨基苯酚的研究

利用源于粘质沙雷氏菌(Serratia marcescens)AB 90027的酶催化过氧化氢氧化降解对氨基苯酚,对降解过程的影响因素和对氨基苯酚的降解途径进行了研究,并分析了酶在细胞中的存在位置.结果表明,降解500mg·l-1对氨基苯酚溶液50ml,其适宜的条件为:H2O23ml,温度40℃-60℃,pH 9.0-10.0;在酶的催化作用下,H2O2氧化对氨基苯酚首先生成对苯醌,进一步氧化生成顺丁烯二酸、反丁烯二酸、草酸等有机酸并最终转化为CO2和H2O.可催化降解对氨基苯酚的酶为胞外酶.     

日本沼虾(Macrobrachium nipponense)N-乙酰-β-D-氨基葡萄糖苷酶初步纯化及部分性质

以日本沼虾内脏为材料,通过硫酸铵沉淀分级分离、DEAE-32离子交换柱层析和SephadexG-100分子筛柱层析纯化,获得比活力为3000Umg-1、纯化倍数为8.88倍的N-乙酰-β-D-氨基葡萄糖苷酶制剂(NAGase).以对-硝基苯-N-乙酰-β-D-氨基葡萄糖为底物,研究酶催化底物水解的反应动力学,结果表明,酶的最适pH为6.0,最适温度为53℃.该酶在pH4.5~9.3区域较稳定,当pH>9.3很快失活;在50℃以下处理30min,酶活力保持稳定,高于50℃,酶稳定性较差,75℃酶完全失活.酶促反应动力学符合米氏双曲线方程,测得米氏常数Km为0.165mmolL-1,最大反应速度Vm为6.55μmolL-1min-1.酶催化pNP-β-D-GlcNAc反应的活化能为63.55kJmol-1.图5表1参16     

石油烃降解酶及其基因的结构、功能和表达调控

研究烃降解酶及其基因是进行石油微生物分子检测和工程菌构建的重要基础.本文对目前烃降解酶及其基因的结构、功能和调控机制的最新研究进展进行了总结.催化烷烃好氧降解的起始酶有几类加氧酶,膜整合甲烷单加氧酶、萘-1,2-双加氧酶和异丙苯双加氧酶的晶体结构已经被解析.烷基或芳基琥珀酸合酶催化烃厌氧代谢的主要起始反应,而Azoarcus sp.乙苯厌氧代谢起始反应由乙苯脱氢酶催化.在细菌中,烃代谢相关基因主要通过形成操纵子进行表达调控,基因转录受烃或类似物诱导,并受细胞全局调控.一些微生物由于存在多种烃代谢途径而可能具有复杂的基因调控机制.此外,生态学研究表明,环境中烃降解基因的诱导动态与实验室内纯培养分析不同.在分析石油降解工程菌构建有待解决问题的基础上,提出了烃代谢综合调控和环境中相关酶及基因诱导研究的重要性,并对未来烃降解酶及其基因在有毒物降解理论研究和生物修复上的应用进行了展望.     

大气汞氧化还原过程与机制的计算化学研究进展

大气中汞的氧化还原反应对于其全球生物地球化学循环起着极其重要的作用,它促进了汞在全球范围内的扩散.汞主要以气态元素汞的形态释放到大气中,并经历复杂的均相和非均相化学反应,被氧化为活性气态汞和颗粒态汞;同时,活性气态汞也可经过光致还原反应光解生成气态元素汞.计算化学是一种基于理论方法利用计算软件来对化学现象和本质进行解释...     

电子束脱除烟道气中硫和氮过程的计算机模拟

电子束干法脱硫脱硝的技术可以同时去除烟道气中的NOx与SO2。根据该处理方法建立脱除NOx和SO2的化学反应机理，并使用计算机模拟的方法，考察体系温度、辐照剂量和氨浓度与去除效率的关系。     

Nitro polycyclic aromatic hydrocarbons in atmospheric particulate matter of Athens,Greece

Polycyclic aromatic hydrocarbons (PAHs) and nitro polycyclic aromatic hydrocarbons (N-PAHs) are chemical species of proven mutant and carcinogenic activity. In this study, the concentrations of seven different N-PAHs [2-nitronaphthalene (2N-NAP), 2-nitroflourene (2N-FLU), 2-nitroflouranthene (2N-FLA), 3-nitroflouranthene (3N-FLA), 1-nitropyrene (1N-PYR) and 2-nitropyrene (2N-PYR)] were determined in two fractions of atmospheric particulate matter from the atmosphere of Athens: coarse (2.4 μm?10 μm ) and fine (<2.4 μm ). 3N-FLA was not detected, whereas 1N-PYR, mostly originating from emissions from burning fuel, showed the maximum observed concentrations for both fractions and for the whole experimental period (especially during winter). In addition, 2N-FLA, a secondary nitro-PAH produced by photochemical reactions, showed relatively high values. Analysis of statistical data for N-PAH concentrations, using clustering technique, showed that: (1) 1N-NAP, 2N-FLU and 1N-PYR are mainly produced by direct burning; and (2) photochemical reactions are the dominant sources of 2N-NAP, 2N-PYR and 2N-FLA.     

Gas-phase and aerosol chemistry interactions in South Europe and the Mediterranean region

The atmospheric chemical composition is affected by the interaction mechanisms among gases and particulate matter through a wide range of chemical reactions that can occur with the aid of particulate matter (e.g. particles act as reacting or absorbing surfaces) or be influenced by the presence of particulate matter in the atmosphere (photochemical reactions). Physical and chemical processes are also bonded in an interactive way that often leads to the influence of the radiation budget, cloud physics and the warming or cooling of the lower atmospheric levels. The Euro-Mediterranean region is a key-sensitive area due to the unique climatic and air quality characteristics associated with the regional climatic patterns, geomorphology (land and water contrast) and coexistence of pollutants from different origin. Focusing on this region, the gas-aerosol interactions are studied using state-of-the-art atmospheric and chemical transport modeling tools following the necessary development in the chemical transport model CAMx. Sensitivity and large-scale simulations have shown significant responses of the modeling system to the inclusion of natural species emissions, the direct shading effect of dust particles on photochemical processes and the formation of new types of aerosols through heterogeneous uptake of gases on dust particles. Including such interactions in the chemical transport model often led to the improvement of the model performance compared with available measurements in the region.     

Equation for isotope accumulation in products and biomass as a way to reveal the pathways in mesophilic methanol methanization by microbial community

Isotope-labelling of substrate is used to reveal the methabolic pathways of substrate transformation by microbial community. In this paper, in order to describe the batch mesophilic anaerobic methanization of ¹³C-labelled methanol and microbial ecology analysis (Li et al., 2008), an equation for the isotope accumulation in products and biomass was included into the basic mathematical model based on stoichiometric chemical reactions. The higher was the isotope level in substrate, the larger fraction of ¹³C accumulated in products and biomass. Acetate, total organic and inorganic carbon (TOC, TIC) concentrations and methane production were used for the model calibration, whereas ¹³C enrichment of acetate, TIC and biomass were used for model validation. In the model, chemical transformations including methanol and acetate oxidation, homoacetogenesis, hydrogenotrophic and aceticlastic methanogenesis were considered. The rate-limiting reactions were methanol and acetate consumption. According to the model, homoacetogens performing acetate formation and oxidation were competed with hydrogenotrophic methanogens for hydrogen. Biphasic methane production was due to hydrogenotrophic methanogenesis in the first phase and due to acetiticlastic and hydrogenotrophic methanogenesis following acetate oxidation in the second phase.     

Population dynamics of beech scale (Cryptococcus fagisuga) (Coccina,Pseudococcidae) related to physiological defence reactions of attacked beech trees (Fagus sylvatica)

Summary Changes in the density of beech scale infestation (Cryptococcus fagisuga) of a mature beech stand (Fagus sylvatica) were investigated after gap-cutting in limed and unlimed areas bordering on the gaps and in untreated areas over a 5-year period. Parallelly the concentrations of sucrose, protein amino acids, and procyanidins were examined in the inner and outer bark of non-infested beech trees and beeches infested by beech scale.Irrespective of liming in the areas bordering on the gaps the proportion of beech trees with increasing beech scale infestation was significantly higher, the proportion of beeches with diminishing infestation was significantly lower than in the untreated control areas. Trees with the same infestation tendency occurred in clusters.Physiological defence reactions in the inner and outer bark of the infested beech trees were registrated as an increase in the procyanidin content and a decrease in the protein amino acid content. A change in the outer bark—inner bark—ratio of the infested beech trees showed a transfer of compounds between the inner and outer bark. During the period of observation long-lasting shifts occurred in the pattern of compounds of the bark irrespective of actual infestation intensity.     

Toxizitätsänderungen in Photoreaktionen von Azaarenen

The azaarenes and the structurally analogous PAH accompany each other and occur ubiquitously in nature. Photochemical conversions like direct photolysis or the photoreaction with nitrate are important natural degradation reactions of azaarenes. Furthermore, photoreactions with chlorine and bromine radicals can be expected in nature. The reactions generate a large number of oxidized, nitrated and halogenated products with unknown toxicity. In this paper, a first screening of changes is reported in acute toxicity during the course of the photochemical reactions. As test system luminescent bacteria are used. For quinoline, isoquinoline and phthalazine the investigations show different changes of the toxicity of the reaction mixtures in dependence on the respective reaction type. The toxicity of the reaction mixtures of quinazoline and quinoxaline increases in all reactions investigated. Furthermore the reactions of bromine radicals with azaarenes also show an increase of the toxicity in all cases. Compared with the azaarenes in all reactions products with significantly higher toxicity are formed.     

Modelling the formation of biogenic iodine in marine aerosols

Models for the formation of biogenic iodine in marine aerosols have been proposed in the literature. Here, we analyse the possible species and reactions that could occur in the proposed models. We calculate the enthalpies of formation for the species and the enthalpies of corresponding reactions. We propose a modified model using iodous acid (HOIO) and reactions that are particularly suited to humid conditions.Selected article from the Regional Symposium on Chemistry and Environment, Krusevac, Serbia, June 2003, organised by Dr. Branimir Jovancicevic     

Recent progress on synthesis of ZIF-67-based materials and their application to heterogeneous catalysis

In recent years, an increasing amount of interest has been dedicated to the synthesis and application of ZIF-67-based materials due to their exceptionally high surface area, tunable porosity, and excellent thermal and chemical stabilities. This review summarizes the latest strategies of synthesizing ZIF-67-based materials by exploring the prominent examples. Then, the recent progress in the applications of ZIF-67-based materials in heterogeneous catalysis, including catalysis of the redox reactions, addition reactions, esterification reactions, Knoevenagel con-densations, and hydrogenation–dehydrogenation reactions, has been elaborately discussed. Finally, we end this work by shedding some light on the large-scale industrial production of ZIF-67-based materials and their applications in the future.     

大气硫酸酯研究进展

硫酸酯是一类含有-OSO_3H基团的有机化合物。它在大气中普遍存在。异戊二烯、单萜、倍半萜、芳烃、醛等均可通过大气自由基反应或非均相反应生成硫酸酯。本文在充分研读已有文献的基础上,总结探讨硫酸酯的分子结构、形成机制、分析方法以及硫酸酯对气溶胶有机物的贡献。最后,对未来研究的热点方向加以展望。