共查询到20条相似文献,搜索用时 15 毫秒
1.
NAD+、NADP+、NADH、NADPH等四类烟酰胺类辅因子也被称为氧化还原辅因子,是维持细胞氧化还原平衡,驱动胞内许多分解与合成反应的重要分子。近年来,辅因子在生物转化系统中的作用受到研究者的重视,氧化还原辅因子更成为人们关注的重点。文章综述了大肠杆菌(Escherichia coli, E. coli)氧化还原辅因子代谢工程研究的最新进展,重点总结最近发展的氧化还原辅因子代谢工程策略,讨论不同代谢工程策略对细胞氧化还原辅因子水平的影响及其在生物合成中的应用,并展望了辅因子代谢工程未来发展方向。 相似文献
2.
The organometallic compound [Cp*Rh(bpy)(H2O)]2+ is a versatile catalyst for the in situ regeneration of reduced nicotinamides and flavins by catalyzing the electron transfer between the cathode or formate to the oxidized cofactors and prosthetic groups. In the present contribution we demonstrate the feasibility of phosphite as an alternative source of reducing equivalents. Thus, [Cp*Rh(bpy)(H2O)]2+ combines the catalytic activities of hydrogenases, formate and phosphite dehydrogenases in one catalyst. The catalytic properties of this novel regeneration approach are investigated, demonstrating that the general catalytic properties of [Cp*Rh(bpy)(H2O)]2+ are preserved. The principal applicability to promote alcoholdehydrogenase‐catalyzed reduction reactions is demonstrated. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
3.
4.
A. V. Vvedenskii T. V. Kartashova E. V. Bobrinskaya 《Russian Journal of Electrochemistry》2008,44(12):1373-1381
The theory of linear-sweep voltammetry (LSV) applied to heterogeneous redox reactions accompanied by the nondissociative adsorption of the reactant or the product is developed. The basic criterial relationships of LSV in this case are invariant with respect to the type of adsorption isotherm and the number of adsorption sites occupied by one species. The degree of irreversibility of the discharge-ionization step can be evaluated from the effect of the potential scan rate on the peak potential. The nature of the adsorbate can be deduced from the effect of the reactant concentrations on the peak current. 相似文献
5.
Water is a suitable medium for the Petasis-borono-Mannich multicomponent reaction. Salicylaldehyde, glyoxalic acid, glycoaldehyde and glyoxal were reacted with several boronic acids and different amines affording alkylaminophenols, 2H-chromenes, α-amino acids, α-amino alcohols and 2-hydroxylmorpholines in good to high yields. An efficient new one-pot method for the assembly of boron-heterocycles based on amino-acids, boronic acids and salicylaldehyde using water as the reaction media is presented. The mechanisms of these reactions were studied by means of DFT calculations, and the effect of solvent on the calculated energy barriers was addressed, for different aldehydes. 相似文献
6.
V. A. Sadykov A. Ya. Rozovskii V. V. Lunin G. I. Lin G. M. Alikina G. A. Buchtiyarova B. P. Zolotovskii S. A. Beloshapkin 《Reaction Kinetics and Catalysis Letters》1999,66(2):337-341
The rate-limiting stage of heterogeneous catalytic redox reactions with participation of strongly bound surface species, such
as nitrates, carbonates and sulfites, is the interaction of these heteroatomic oxidants with the reducing agents. It appears
to be mainly determined by their bonding strength with the surface, being independent of the nature of the central atom (carbon,
sulfur, nitrogen) and the energy of its bond with oxygen. 相似文献
7.
Ahmed T. Mubarak Ashraf A. Mohamed Khalid F. Fawy Ayed S. Al-Shihry 《Mikrochimica acta》2007,157(1-2):99-105
An extremely sensitive and selective kinetic method was developed for the determination of trace levels of nitrite based on
its catalytic effect on the oxidation of perphenazine (PPZ) with bromate in a phosphoric acid medium. The reaction rate was
monitored spectrophotometrically by tracing the formation of the red-colored oxidized product of PPZ at 525 nm within 30 sec
of mixing. The optimum reaction conditions were 4.0 μmol L−1 PPZ, 0.4 mol L−1 H3PO4 and 30 mmol L−1 bromate at 25 °C. Using the recommended procedure, nitrite could be determined with a linear calibration graph up to 4.50 ng mL−1 and a detection limit of 0.07 ng mL−1. The method was conveniently applied to the determination of nitrite in samples of rain, polluted well and formulated waste
waters. Moreover, the published kinetic spectrophotometric methods for nitrite determination are reviewed. 相似文献
8.
Kosevich MV Chagovets VV Shmigol IV Snegir SV Boryak OA Orlov VV Shelkovsky VS Pokrovskiy VA Gomory A 《Journal of mass spectrometry : JMS》2008,43(10):1402-1412
Redox behaviour of four imidazophenazine dye derivatives under mass spectrometric conditions of matrix-assisted laser desorption/ionization (MALDI), laser desorption/ionization (LDI) from metal and graphite surface, electrospray, low temperature secondary ion mass spectrometry (LT SIMS) and fast atom bombardment (FAB) was studied and distinctions in the reduction-dependent spectral patterns were analyzed from the point of view of different quantities of protons and electrons available for reduction in different techniques. The reduction products [M + 2H](+*), [M + 3H](+) and M(-*), [M + H](-) were observed in the positive and negative ion modes, respectively, which permitted to suggest independent occurrence of reduction and protonation/deprotonation processes. LDI from graphite substrate was the only technique that allowed us to obtain abundant negative ions of all dye derivatives. The yield of field ionization (FI) or field desorption (FD) mechanism to ion formation under LDI from rough graphite surface has been addressed. The sensitivity of reduction of the dyes to variation of reduction-initiating agents confirms high redox activity of the dyes essential for their functioning in natural and artificial systems. 相似文献
9.
LI Di SUN Chunyan HUANG Yunjie LI Jinghong & CHEN Shaowei . State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun China . Department of Chemistry Tsinghua University Beijing China . Department of Chemistry University of California Santa Cruz Santa Cruz CA USA 《中国科学B辑(英文版)》2005,48(5):424-430
The intense research interest in nanosized particle materials is mainly fueled by their unique physical, chemical, electronic, and magnetic properties[1]. Among these, they have shown great application po-tentialities in the catalytic regulation of elec-t… 相似文献
10.
该文建立了一种可视化的、基于氧化还原反应界面移动距离定量检测辣根过氧化物酶(HRP)的方法。比较了隐色结晶紫显色体系和3,3′,5,5′-四甲基联苯胺显色体系对HRP的显色效率,并构建了基于3,3′,5,5′-四甲基联苯胺显色体系的氧化还原反应电泳滴定模型。同时,文中还设计了适用于该模型的小型化、便携式滴定检测芯片,并对滴定通道凝胶中组分进行了优化。结果表明,界面移动距离与HRP浓度存在对数线性关系,检测灵敏度可达0.002 mg/L,且可在10 min内完成HRP的裸眼检测。该方法不需要配备信号读取装置,用户只需要读取有色界面移动的距离即可实现对待测物的可视化定量检测,对于即时检测具有潜在的应用价值。 相似文献
11.
Minghui He Shun Jiang Ruixin Xu Jianwen Yang Zhaohua Zeng Guangxue Chen 《Journal of polymer science. Part A, Polymer chemistry》2014,52(11):1560-1569
A detailed evaluation of the kinetics of domino free radical photopolymerization (DFRP) based on phototriggered base proliferation reaction and redox initiation was described in the condition of eliminating the heat of polymerization via reacting in the thin polymer films. First, domino photoinitiating system made a substantial breakthrough in the photoefficiency of amine generation in contrast to photocaged base system, exhibiting marked improvement in the photosensitivity. Second, both the structural feature of base amplifier (BA) and reaction temperature as two important factors impacting the proliferation rate have been detailed. Third, different domino photoinitiating components, such as BAs, peroxides, and acrylates, were investigated in the thin polymer films. It is shown that both primary and secondary BAs are efficient catalysts for DFRP. Furthermore, polymerization rate shows a consistent dependence on the pKa value of the proliferated amine. Finally, remarkable post conversion after irradiation was achieved in DFRP. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1560–1569 相似文献
12.
In this short review we describe some of the main developments of polymer reaction engineering since the early days of polymer science in the 1930's to the current challenges of today. 相似文献
13.
Nobuhiro Sugihara Yoshiro Ogoma Koji Abe Yoshimasa Murakami Yoshiyuki Kondo Toshihiro Akaike 《先进技术聚合物》1999,10(5):265-269
The relationship between the redox reaction of camphor‐induced cytochrome P‐450 (P‐450cam) and its activity was measured by using cyclic voltammetry. The redox potential of P‐450cam solution shifted to the lower side of the potential by binding of substrate, and the change was proportional to the amount of the substrate binding to the protein. The substrate binding was inhibited at the low concentration of oxygen in the reaction solution. The reaction product, hydroxycamphor, was observed in the reaction mixture by gas chromatography/mass spectroscopy. However, hydroxycamphor was not observed at an oxygen concentration of about a tenth part of the saturated one. The shift of redox potential of P‐450cam solution corresponded to the substrate specificity of the activity. These results suggest that the redox reaction of P‐450cam related to the substrate‐binding to the protein and its activity. Furthermore, the present system was very simple and speedy for the measurement of the activity. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
14.
A model describing the steady-state kinetics of thermal decomposition in the solid phase occurring with a decrease in the
solid phase volume and accompanied by fracture in the reaction zone is suggested. The model is based on the concept of positive
feedback between the reaction and fracture. The rate of the fracture front and the size of the product fragments formed were
calculated.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 626–631, April, 1998. 相似文献
15.
In this work, P2-Na0.6[Mg(II)0.3Mn(IV)0.7] O2 with inoxidizable elements (Na+, Mg2+ and Mn4+) except O2- was synthesized and investigated, which exhibited high reversible capacity (~210 mAh/g) with highly reversible ARR characteristic. 相似文献
16.
《Journal of Coordination Chemistry》2012,65(14):2267-2280
AbstractModel complexes [MoVIO2(S2C2Me2)SMe]? (A, derived from the X-ray crystal structure of native sulfite oxidase (SO)) and [MoVIO2(mnt)2]2? (B, coordination mode similar to the active site of selenate reductase (SeR)) were computed at the COSMO-B3LYP/SDDp//B3LYP/Lanl2DZ(p) energy level of Density Functional Theory in order to study their behavior in oxidation of selenite (SeIV) and sulfite (SIV) to selenate (SeVI) and sulfate (SVI), respectively. For the oxidation of sulfite, computational model A, which resembles the SO active site, is clearly the best choice (lowest barrier, minor exothermicity). For the reduction of selenate, a smaller activation is computed for model A; however, the reaction is less exothermic with model B, which resembles the SeR active site. 相似文献
17.
Andrey Kh. Vorobiev Denis Menshykau 《Journal of photochemistry and photobiology. A, Chemistry》2008,197(2-3):359-363
The kinetics of photochemical reactions in optically dense media essentially free from diffusion was considered. The photochromic isomerization A ↔ B was studied as an example. If thermal isomerization is possible, a stationary state is achieved in time determined by rate constants for the thermal reactions. The concentration wave profile is changed during the photochemical reaction propagation. Low values of thermal reaction constants and decrease in sample optical density during photochemical isomerization were found to be essential for maximal wave penetration into the sample. Sharp concentration gradients of A and B can be observed when both the optical density is increased during photochemical isomerization and the quantum yield of the direct photochemical reaction A → B is higher than that of the reverse photochemical reaction B → A. 相似文献
18.
The potential energy surface for the Cl + propene reaction was analyzed at the MP2 level using Pople's 6-31G(d,p) and 6-311+G(d,p), and Dunning's cc-pVDZ and aug-cc-pVDZ basis sets. Two different channels for the addition reaction leading to chloroalkyl radicals and five alternative channels for the abstraction reaction leading to C(3)H(5) (.) + HCl were explored. The corresponding energy profiles were computed at the QCISD(T)/aug-cc-pVDZ//MP2/aug-cc-pVDZ level of theory. Theoretical results suggest that the previously established mechanism consisting of (1) direct abstraction and (2) addition-elimination steps is instead made up of (1) addition through an intermediate and (2) two-step abstraction processes. No direct abstraction mechanism exists on the potential energy surface. The kinetic equations derived for the new mechanism are consistent with the pressure dependence experimentally observed for this reaction. 相似文献
19.
《Journal of computational chemistry》2017,38(20):1780-1788
The (nitro)(N‐methyldithiocarbamato)(trimethylphospane)nickel(II), [Ni(NO2)(S2CNHMe)(PMe3)] complex catalyses efficiently the O‐atom transfer reactions to CO and acetylene. Energetically feasible sequence of elementary steps involved in the catalytic cycle of the air oxidation of CO and acetylene are proposed promoted by the Ni(NO2)(S2CNHMe)(PMe3)] ↔ Ni(NO2)(S2CNHMe)(PMe3) redox couple using DFT methods both in vacuum and dichloromethane solutions. The catalytic air oxidation of HC≡CH involves formation of a five‐member metallacycle intermediate, via a [3 + 2] cyclo‐addition reaction of HC≡CH to the Ni‐N = O moiety of the Ni(NO2)(S2CNHMe)(PMe3)] complex, followed by a β H‐atom migration toward the Cα carbon atom of the coordinated acetylene and release of the oxidation product (ketene). The geometric and energetic reaction profile for the reversible [Ni( ‐NO2)(S2CNHMe)(PMe3)] [Ni( ‐ONO)(S2CNHMe)(PMe3)] linkage isomerization has also been modeled by DFT calculations. © 2017 Wiley Periodicals, Inc. 相似文献
20.
《Journal of computational chemistry》2018,39(19):1319-1326
Many catalytic and biomolecular reactions containing transition metals involve changes in the electronic spin state. These processes are referred to as “spin‐forbidden” reactions within nonrelativistic quantum mechanics framework. To understand detailed reaction mechanisms of spin‐forbidden reactions, one must characterize reaction pathways on potential energy surfaces with different spin states and then identify crossing points. Here we propose a practical computational scheme, where only the lowest mixed‐spin eigenstate obtained from the diagonalization of the spin‐coupled Hamiltonian matrix is used in reaction path search calculations. We applied this method to the 6,4FeO+ + H2 → 6,4Fe+ + H2O, 6,4FeO+ + CH4 → 6,4Fe+ + CH3OH, and 7Mn+ + OCS → 5MnS+ + CO reactions, for which crossings between the different spin states are known to play essential roles in the overall reaction kinetics. © 2018 Wiley Periodicals, Inc. 相似文献