大肠杆菌L- 天冬酰胺酶的分离纯化及其特性

目的 建立简单有效的L- 天冬酰胺酶分离纯化工艺，研究L-天冬酰胺酶的特性。方法 采用冷丙酮破壁处理，经稀碱液抽提、离子交换层析和亲和层析进行纯化。通过温度试验、pH试验、SDS－PAGE图谱、紫外吸收光谱等研究酶的特性。结果 建立了简单高效的纯化工艺，可使L-天冬酰胺酶的纯度达94．4％，比活为520u/mg蛋白，总收率为65．7％。L-天冬酰胺酶的相对分子质量分别为143900和166700，均为有抗癌活性的EC－2组分，在270nm有最大吸收。最适作用温度为40－50℃，最适作用州为8.0-9.0在40℃以下能保持稳定。结论建立了大肠杆菌L-天冬酰胺酶的分离纯化工艺，并研究了L-天冬酰胺酶的酶学特性。     

尿卟啉原Ⅲ合成酶研究进展

尿卟啉原Ⅲ合成酶（UrogenⅢs）是四吡咯化合物生物代谢中的关键酶之一,它催化羟甲基胆素重排环合形成天然四吡咯化合物的共同前体-尿卟啉原Ⅲ。总结了UrogenⅢS在生化性质、晶体结构、催化机理等方面的研究成果。     

氨基酸生物合成中除草剂靶酶研究进展

氨基酸在植物的生长过程中起着至关重要的作用,以氨基酸生物合成过程中的酶作为靶标,是研发除草剂的一个重要方向和热点。ALS、EPSPS等是非常成功的除草剂靶酶。随着植物生理和生物化学的发展,氨基酸生物合成中的除草剂靶酶的研究有了新的进展,开发出新的潜在的除草剂靶酶和具有一定除草效果的潜在抑制剂。     

具有除草活性的1,4-桉树脑衍生物的研究进展

1，4-桉树脑衍生物是一类具有良好除草活性的化合物。概述了具有烷氧基、取代苯氧基、取代苄氧基以及杂(并)环氧基四种结构类型桉树脑类衍生物的结构与除草活性的关系，阐述了取代基的变化对除草活性的影响以及它们作为苗前和苗后除草剂的应用效果。此外，还介绍了1，4-桉树脑衍生物除草作用机理的研究动态，研究表明，1，4-桉树脑衍生物可作为天冬酰胺合成酶抑制剂。     

神经氨酸酶抑制剂的研究进展

神经氨酸酶在微生物和病毒侵染宿主过程中有重要作用,使用神经氨酸酶抑制剂是抑制侵染的有效方式,因此,基于神经氨酸酶和底物的结构设计、合成神经氨酸酶抑制剂是近年来的研究热点。由于微生物的广泛性,利用微生物来源的神经氨酸酶和底物结合是开发抑制剂的主要途径。简单介绍了神经氨酸酶的结构和应用,着重就神经氨酸酶抑制剂的研究进展进行了综述。     

HPPD抑制剂类除草剂及其市场开发进展

HPPD抑制剂类除草剂是近年除草剂研究开发的热点之一。介绍了10多个此类除草剂及其市场与应用开发进展。     

新型乙酰乳酸合成酶(ALS)抑制剂的研究进展

ALS抑制剂不仅具有超高除草活性 ,而且这类除草剂对人和动物十分安全 ,近年来 ,ALS抑制剂的研究一直是除草剂开发中的热点。综述了近十多年来 ALS抑制剂的研究和应用进展。     

黄酮类神经氨酸酶抑制剂的研究进展

神经氨酸酶(Neuraminidase,NA)是抗流感病毒药物的重要靶点。近年来研究者发现一系列黄酮类化合物对流感病毒NA有很好的抑制作用,其结构与传统NA抑制剂差异较大。文章综述了近年来报道的黄酮类NA抑制剂的研究进展,为抗流感病毒药物先导化合物的筛选和设计提供借鉴和参考。     

神经氨酸酶抑制剂研究进展

流感是由流感病毒引起的呼吸道传染病。对人类的健康危害极大。神经氨酸酶(NA)在流感病繁殖过程起重要作用,通过抑制NA可阻止流感的蔓延,从此神经氨酸酶成了抗流感病毒药物理想的进攻靶点,基于神经氨酸酶与底物的酶促活性结构合理设计的神经氨酸酶药物相继上市,该文对扎那米韦,奥斯米伟及帕拉米韦高活性衍生物的研究做了综述。     

葡萄糖胺-6-磷酸合成酶的异源表达及其酶学性质表征

葡萄糖胺-6-磷酸合成酶(GFA)是己糖胺生物合成中的一个关键酶,为建立一条高效的GFA生产工艺,其研究对象GFA来源于致病菌白色假丝酵母(Candida albicans ATCC 64548),通过基因克隆,然后在大肠杆菌中进行异源表达.结果显示,GFA的最佳异源表达条件为:诱导剂浓度为0.1 mmol.L-1,诱...     

MoP-U在22.4%食盐溶液中对碳钢的协同缓蚀作用与机理研究

采用失重法,表面观察法,极化曲线法、氩离子刻蚀时和ＸＰＳ分析法研究ＭｏＰ－Ｕ在２２．４％食盐溶液中对碳钢的协同缓蚀作用与 。结果发现５０％ＭｏＰ＋５０％Ｕ（ＸＭ－６０６）在２２．４％食盐溶液中对碳钢具有显著的协同缓蚀效应。     

Preparation of carboxy sulfonic acid-containing copolymer scale inhibitors and their scale inhibition effect on CaCO3

Free radical polymerization was selected to obtain a promising copolymer scale inhibitor IA-AM-SAS with good water solubility and temperature and salt resistance, which is suitable for the treatment of surface pipeline water in oil fields, using itaconic acid (IA), acrylamide (AM), and sodium acrylsulfonate (SAS) as the monomers. The structure of the synthesized copolymer was verified by Fourier transform infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy. Thermogravimetric results showed that the copolymer does not undergo significant thermal degradation at temperatures below 356°C, indicating that the copolymer has good thermal stability. The molecular weights of the polymers at different monomer ratios were measured using gel permeation chromatography and the relationship between the molecular weights and scale inhibition performance was discussed. The results showed that the scale inhibition effect was best when the monomer molar ratio n(IA): n(AM): n(SAS) was 0.5:2:1.5 and the number of average molecular weight of the prepared copolymer was 7712 g/mol, and the inhibition efficiency of CaCO₃ was 84.02% when IA-AM-SAS was at a concentration of 30 mg L⁻¹, and the inhibition rate was measured by the standard of static scale inhibition test in the oilfield measured. The range of conditions (PH, Ca²⁺ concentration, water temperature, and time) of the static scale inhibition test was then expanded using a one-way controlled variable experiment to explore the performance of IA-AM-SAS scale inhibitors under different water quality conditions. The scale inhibition mechanism was explored by scanning electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. Briefly, the combination of multiple functional groups enables IA-AM-SAS to be applied in complex and challenging environments.     

咪唑啉季铵盐缓蚀剂的合成及应用研究

综述了有机缓蚀剂的种类及缓蚀机理,并详细介绍了新型水溶性咪唑啉季铵盐类缓蚀剂的合成及在石油化工领域的应用现状。     

新型环保阻燃剂的研究进展

介绍了金属氢氧化物、溴系、有机磷系阻燃剂等新型环保阻燃剂的研究状况,指出烷基次膦酸盐是应电子电器工业需要而产生的、具有发展前景的阻燃剂。     

Synthesis and characterization of solid-phase super acid catalysts and their application for isomerization of n-alkanes

In the present work, first, the reference catalyst super acidic nanostructured sulfated zirconia (SZ) and super acidic nanostructured aluminum chloride impregnated sulfated zirconium oxides in mole ratios of Zr⁴⁺:Al³⁺ as 2:1 (ACSZ-1), 1:1 (ACSZ-2), and 1:2 (ACSZ-3) were synthesized by a simple precipitation method. The catalytic performance of these four catalysts were evaluated during the isomerization of n-hexane, n-heptane, and n-octane to their corresponding branched chain isomers at low temperature and pressure conditions. ACSZ-2 shows high activity toward isomerization of n-hexane, n-heptane, and n-octane into their corresponding branched chain isomers. The reference catalyst SZ was proved to be less effective compare to the other three synthesized ACSZ catalysts. Ammonia-temperature-programmed desorption of these two materials ensures that the super acidity of ACSZ-2 is higher than that of SZ. Atomic force microscopic and scanning electron microscopic pictures predict the nature of the surface of the catalysts. Transmission electron micrographic analysis indicates the presence of particle-bulks having average size 12–20?nm, presenting an amorphous nature and having no definite surface morphology of ACSZ-2. Fourier transform infrared provides an outline regarding different linkages and bond connectivities between atoms and groups in ACSZ-2 and SZ. After catalyst evaluation and characterization a probable reaction mechanism has been proposed theoretically. The reactivity and selectivity of ACSZ-2 and SZ as well as the order and activation energy of the isomerization reactions in presence of ACSZ-2 have been calculated. The use of ACSZ-2 is beneficial from the point of cost efficiency as well as its use is energy saving.     

明胶的酶降解反应动力学研究——Ⅱ.动力学规律和机理

根据文献[1]中的实验数据,结合化学反应动力学的基础理论,计算了明胶的酶降解反应的反应级数、表观活化能、指前因子等有关动力学参数值。得到反应的总速率方程。所求得的反应速率常数与温度的关系表明,在实验温度范围内,符合Arrhenius公式。最后提出了该反应的酶催化反应机理,实验结果与所推得的机理动力学方程相吻合。     

烟气脱硫脱氮技术进展

从烟气脱硫脱氮技术的机理出发,介绍了目前有代表性的3类烟气净化技术：烟气脱硫技术、烟气脱氮技术、烟气同时脱硫脱氮技术的机理和特点。相比于单独的脱硫脱氮技术,认为同时脱硫脱氮技术具有良好的经济性和灵活的技术选择性。提出了适合我国国情的烟气污染治理技术的发展方向。     

Fe基MILs材料的制备与应用研究进展

金属-有机骨架化合物(Metal-Organic Frame-works,MOFs)是由无机金属离子或离子簇与有机配体配位而成的一类具有周期性网状结构的新型多孔晶体材料。众多MOFs材料中,Fe基拉瓦锡骨架材料(Materials of Institute Lavoisier Frameworks,MILs)因具有良好生物相容性、独特的骨架柔性、突出的比表面积及高度稳定性,在医学、传感、催化等领域有着广泛的应用前景。研究者们通过合成方法创新、结构修饰以及与其他材料复合等方式对Fe基MILs的结构与性能进行优化,进一步提升了Fe基MILs材料及相关材料的实际应用效果、扩展了其应用范围。本文从Fe基MILs的种类及其结构特征入手,重点综述了其常见的合成方法及改性方法,总结了Fe基MILs在药物载体、传感、吸附和催化等方面的应用,在此基础上讨论了Fe基MILs在上述领域中的应用优势及局限性,并对其发展趋势进行了展望。     

Kinetics of methylamine conversion on a Pd catalyst in the presence of H2

The kinetics of disproportionation of methylamine to dimethylamine and ammonia in the presence of hydrogen have been investigated over a silica-supported palladium catalyst. At a fixed partial pressure of methylamine, the reaction rate generally increases with decreasing hydrogen partial pressure, approaching a limiting or maximum value at sufficiently low pressures of hydrogen. The existence of a maximum is supported by the observation that the presence of some hydrogen appears to be necessary for the reaction to proceed at a conveniently measurable rate. At a fixed hydrogen partial pressure, the reaction rate increases with increasing methylamine partial pressure. When the methylamine partial pressure is sufficiently low or the hydrogen partial pressure is sufficiently high, the reaction order with respect to methylamine can be somewhat higher than one. At such conditions, a mechanism involving a bimolecular reaction between two partially dehydrogenated methylamine molecules on the surface appears to make a significant contribution to the overall catalytic reaction.     

生物柴油低温流动性及其降凝剂的研究进展

生物柴油是典型的"绿色可再生能源".然而生物柴油的凝点一般在0℃时,其低温结晶和凝胶化限制了生物柴油在低温时的应用.生物柴油低温流动性能主要与生物柴油中的饱和脂肪酸甲酯的含量和分布有关,还与脂肪酸酯的支链程度有关.综述了改善生物柴油低温流动性的方法,降凝剂的作用机理及生物柴油降凝剂的研究、应用及发展前景.