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91.
92.
用微量热法研究漆酶和过氧化氢的反应 总被引:6,自引:0,他引:6
漆树酶是含铜酶。在酶系统中属于一种选择性较差的氧化酶,它能与许多还原底物作用,同时亦能还原分子氧生成水。在这些反应中漆酶中的三个不同的氧化还原活性中心和其作用途径常常是研究中的主要对象。在无氧条件下,漆酶被底物还原后,可用氧再氧化,实验表明,酶分子中的Cu2~+—Cu~(1+)循环是催化机理的一部分。1970年Farver等人在研究漆树酶与过氧化氢之间的反应时发现,漆树酶与过氧化氢有一种特殊作用,二者会生成一种稳定的具有高亲合力的复合物,该复合物不会被氧再氧化,其反应可用下式表示:式中L-Cu(Ⅱ)表示含二价铜的漆酶分子,二价铜在此反应中起活性中心的作用。本工作中,用微量热法测量了漆树酶与过氧化氢反应的一些热动力学性质。 相似文献
93.
Wanchao Chen Yan Kang Han Zhang Tianxiong Huang Xin Tao Aiping Lu Yiping Du 《中国化学快报》2019,30(5):1027-1030
In this study, a convenient method of preparing the substrate is proposed with one-pot synthesis of silver colloid under body heat, and the SERS detection uses the fresh substrate to avoid the drawback of substrates' short life of use. The synthesis of silver colloid is carried out in a 10 mL vial by using ascorbic acid as a reductant and trisodium citrate as a stabilizer. The vial is grasped with the palm of the experimenter for several minutes without shaking. The proposed method is simple, rapid, green energy and cost-effective. By adjusting the concentration of trisodium citrate, not only the particle size can be controlled from about 110 nm to 50 nm but also the homogeneity of nanoparticles can be improved. As a SERS substrate, the silver colloid has high batch reproducibility and showed good SERS activity. The relative standard deviation between different manufacturers is 5.51% when the substrate of silver colloid is used for the detection of rhodamine 6 G. Using the substrate, the lowest detection concentrations of rhodamine 6 G, crystal violet, enrofloxacin, melamine and leucomalachite green are 1.0×10~(-8), 6.1×10~(-8),1.4 × 10~(-6), 7.1 ×10~(-5) and 5.1 ×10~(-8) mol/L, respectively. Results demonstrate that the developed method has the advantage of convenience and high efficiency in the field preparation of reliable SERS substrate. 相似文献
94.
《中国化学快报》2020,31(4):931-936
MXenes,the new family of two-dimensional(2D) transition metal carbides/nitrides,can serve as the substrate materials for the catalysts due to the large specific surface area,tunable electronic structures and thermal stability.The first 2D layered MXene,Ti_3C_2,was successfully obtained by selective etching of the A element from the MAX phases using hydrofluoric acid(HF) at room temperature in 2011.In this review,we summarize the preparation,structure of MXenes and discuss the recent progress in potential application of MXenes in catalysis,mainly in CO oxidation and oxygen reduction reaction(ORR),from the views of both experimental and theoretical inve stigations.The outlook of the major challenges and future directions on research of MXenes is also included. 相似文献
95.
研究了PS PMMA的共混物溶液溶剂蒸发成膜时的基板界面效应 .利用扫描电子显微镜 (SEM)研究了PS PMMA(5 5 ) (W W) THF高分子共混物溶液在不同基板上通过溶剂挥发成膜的相形态结构 .通过FTIR及ATR FTIR检测了共混物薄膜及其表面的共混组成 .研究结果表明 ,成膜基板对高分子共混物溶液成膜后的相形态有很重要的影响 .控制共混物溶液体系成膜过程中的动力学因素 ,可以调控出所设想的各种复杂的相结构形态 相似文献
96.
In the frame of substrate specificity, CAL-B-catalysed asymmetric N-alkoxycarbonylations of 1-substituted tetrahydro-ß-carbolines (Me, Et, Pr, iPr) have been studied. High enantioselectivities (>200) were observed, when alkoxycarbonylation of racemic compounds (±)-1,3,5,7 were performed in DIPE in the presence of phenyl allyl carbonate and Et3N at 60?°C using ultrasound shaking method. The reaction time increased considerably with increasing substituent size on C1; however, the isopropyl-substituted compound proved to be too bulky for the optimum activity of CAL-B. The (R)-carbamate enantiomers were hydrolysed using Pd2(dba)3.CHCl3 and the enantiomers of the free amines were obtained with excellent ee (>99%). 相似文献
97.
Kenji Miyamoto 《Tetrahedron letters》2007,48(18):3255-3257
To clarify the substrate specificity of the recombinant styrene oxide isomerase, various epoxides were subjected to the reaction. From the substituent effect on the rate of isomerization, the mechanism of the isomerase catalyzed reaction was estimated. 相似文献
98.
William Porzio Guido Scavia Sergey Arnautov Lucia Conzatti Jérôme Charmet Edith Laux Herbert Keppner Giuseppe Zerbi Luigi Brambilla Alberto Bolognesi 《European Polymer Journal》2011,47(9):1725-1735
Poly(2-chloroxylylene) (PCX) thin films are obtained on the surface of liquids with different density and surface tension values. Morphology of these films is different showing increasing roughness and hydrophobicity in correlation with aforementioned physical parameters. A detailed study by means of vibrational spectroscopy, XRD and TEM of the structure of PCX at the interface with the liquid is reported. The results here obtained prove the possibility to tailor the surface of thin solid films of PCX changing the liquid substrate thus addressing the surface functionalities. 相似文献
99.
Juozas Kulys Heinz-Josef Deussen Kastis Krikstopaitis Palle Schneider Arturas Ziemys 《Monatshefte für Chemie / Chemical Monthly》2001,132(2):295-304
Summary. N-Aryl-N-hydroxy urethanes (AHUs), which are promising N*OH mediators for oxidoreductase catalysis, are electrochemically active redox compounds with a redox
potential of 0.35–0.40 V vs. SCE (0.59–0.64 V vs. NHE). Alkyl substituents in the carbamic acid residue have, as expected, only little influence on the redox potential. The
highest potential was noticed for N-hydroxy-N-(4-cyanophenyl)-carbamic acid methyl ester. Recombinant Coprinus cinereus peroxidase (rCiP) catalyzes oxidation of the AHUs with apparent bimolecular constants k
ox of 2.5ċ104–7.5ċ104 M
−1s−1 at pH = 8.5 and 25°C.
Structure-function connectivities of the substrates were analysed within the framework of the Marcus cross relationship and by using ab initio quantum chemical calculations. An excellent correlation of the redox potentials and the HOMO energies could be found. However,
no correlation of log(k
ox) with redox potential and HOMO energy was indicated as predicted by theory. This was explained by specific docking of the
substrates in the active center of rCiP.
Received June 26, 2000. Accepted (revised) August 9, 2000 相似文献
100.