Academic literature on the topic 'Transition metals; Hydrolytic enzymes'
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Journal articles on the topic "Transition metals; Hydrolytic enzymes"
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Bautista-Expósito, Sara, Irene Tomé-Sánchez, Ana Belén Martín-Diana, Juana Frias, Elena Peñas, Daniel Rico, María Jesús García Casas, and Cristina Martínez-Villaluenga. "Enzyme Selection and Hydrolysis under Optimal Conditions Improved Phenolic Acid Solubility, and Antioxidant and Anti-Inflammatory Activities of Wheat Bran." Antioxidants 9, no. 10 (October 13, 2020): 984. http://dx.doi.org/10.3390/antiox9100984.
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Valorization of wheat bran (WB) into new high-value products is of great interest within the framework of sustainability and circular economy. In the present study, we utilized a multi-step approach to extract nutraceutical compounds (phenolic acids) from WB and improved its antioxidant and anti-inflammatory properties through using sequential hydrothermal and enzymatic hydrolysis. Thirteen commercial glycosidases differing in their specific activity were screened and compared for hydrolytic efficiency to release monosaccharides, ferulic acid, and diferulic acid. Ultraflo XL was selected as the desired enzyme treatment on the basis of its higher WB solubilization, as well as its monosaccharide and phenolic acids yields. The relationships between better hydrolytic performance of Ultraflo XL and its particular activity profile were established. To determine the optimum conditions for Ultraflo XL treatment, we tested different factors (solvent pH, incubation temperature, and time) under 15 experiments. A multicomponent analysis (MCA), including central composite design, model fitness, regression coefficients, analysis of variance, 3D response curves, and desirability, was used for processing optimization. A beneficial effect of autoclave treatment on the release of phenolic compounds was also evidenced. The results of MCA showed involvement of linear, quadratic, and interactive effects of processing factors, although solvent pH was the main determinant factor, affecting enzymatic extraction of phenolics and bioactivity of hydrolysates. As compared to control WB, under optimized conditions (47 °C, pH = 4.4, and 20.8 h), WB hydrolysates showed 4.2, 1.5, 2, and 3 times higher content of ferulic acid (FA) and capacity to scavenge oxygen radicals, chelate transition metals, and inhibit monocyte chemoattractant protein-1 secretion in macrophages, respectively. These approaches could be applied for the sustainable utilization of WB, harnessing its nutraceutical potential.
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Sugrue, Elena, Nicholas J. Fraser, Davis H. Hopkins, Paul D. Carr, Jeevan L. Khurana, John G. Oakeshott, Colin Scott, and Colin J. Jackson. "Evolutionary Expansion of the Amidohydrolase Superfamily in Bacteria in Response to the Synthetic Compounds Molinate and Diuron." Applied and Environmental Microbiology 81, no. 7 (January 30, 2015): 2612–24. http://dx.doi.org/10.1128/aem.04016-14.
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ABSTRACTThe amidohydrolase superfamily has remarkable functional diversity, with considerable structural and functional annotation of known sequences. In microbes, the recent evolution of several members of this family to catalyze the breakdown of environmental xenobiotics is not well understood. An evolutionary transition from binuclear to mononuclear metal ion coordination at the active sites of these enzymes could produce large functional changes such as those observed in nature, but there are few clear examples available to support this hypothesis. To investigate the role of binuclear-mononuclear active-site transitions in the evolution of new function in this superfamily, we have characterized two recently evolved enzymes that catalyze the hydrolysis of the synthetic herbicides molinate (MolA) and phenylurea (PuhB). In this work, the crystal structures, mutagenesis, metal ion analysis, and enzyme kinetics of both MolA and PuhB establish that these enzymes utilize a mononuclear active site. However, bioinformatics and structural comparisons reveal that the closest putative ancestor of these enzymes had a binuclear active site, indicating that a binuclear-mononuclear transition has occurred. These proteins may represent examples of evolution modifying the characteristics of existing catalysts to satisfy new requirements, specifically, metal ion rearrangement leading to large leaps in activity that would not otherwise be possible.
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Grootveld, Martin, Edward Lynch, Georgina Page, Wyman Chan, Benita Percival, Eugenia Anagnostaki, Valina Mylona, Sonia Bordin-Aykroyd, and Kerry L. Grootveld. "Potential Advantages of Peroxoborates and Their Ester Adducts Over Hydrogen Peroxide as Therapeutic Agents in Oral Healthcare Products: Chemical/Biochemical Reactivity Considerations In Vitro, Ex Vivo And In Vivo." Dentistry Journal 8, no. 3 (August 7, 2020): 89. http://dx.doi.org/10.3390/dj8030089.
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Peroxides present in oral healthcare products generally exert favourable protective activities against the development and progression of tooth decay, plaque, gingivitis, and halitosis, etc. However, despite the high level of research focus on hydrogen and carbamide peroxides as therapeutically active (and tooth-whitening) agents, to date the use of alternative chemical forms of peroxides such as peroxoborates for these purposes has received only scant attention. Intriguingly, peroxoborate and its esters with polyols, such as glycerol, have a very diverse chemistry/biochemistry in aqueous solution, for which there is an increasing amount of evidence that it remains distinctive from that of hydrogen peroxide; such properties include self-associative and hydrolytic equilibria, and their abilities to participate in electrophile- or nucleophile-scavenging, metal ion-complexing, redox and free radical reactions, for example. Therefore, the purpose of this detailed commentary is to evaluate both differences and similarities between the molecular/biomolecular reactivities of peroxoborate species and hydrogen peroxide in vitro, ex-vivo and in vivo. It encompasses brief sectional accounts regarding the molecular heterogeneity of peroxoborates, the release of bioactive agents therefrom, and their oxidative attack on oral cavity biomolecules (the nucleophilic or electrophilic character of these oxidations are discussed). Further areas explored are the abilities of borates and peroxoborates to enhance the solubility of iron ions in aqueous solution, their involvements in free radical biochemistry (particularly the complexation of oxygen radical-promoting transition metal ions by, and antioxidant properties of, peroxoborate-polyol ester adducts), and the specific inhibition of protease enzymes. Further aspects focus on the tooth-whitening, oral malodor neutralizing, and potential mutagenic and genotoxic properties of peroxoborates, along with possible mechanisms for these processes. The abilities of peroxoborates, and peroxides in general, to modulate the activities of inflammatory mediators and vitamins, antioxidant or otherwise, are also explored.
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Purg, Miha, Anna Pabis, Florian Baier, Nobuhiko Tokuriki, Colin Jackson, and Shina Caroline Lynn Kamerlin. "Probing the mechanisms for the selectivity and promiscuity of methyl parathion hydrolase." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 374, no. 2080 (November 13, 2016): 20160150. http://dx.doi.org/10.1098/rsta.2016.0150.
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Diverse organophosphate hydrolases have convergently evolved the ability to hydrolyse man-made organophosphates. Thus, these enzymes are attractive model systems for studying the factors shaping enzyme functional evolution. Methyl parathion hydrolase (MPH) is an enzyme from the metallo-β-lactamase superfamily, which hydrolyses a wide range of organophosphate, aryl ester and lactone substrates. In addition, MPH demonstrates metal-ion-dependent selectivity patterns. The origins of this remain unclear, but are linked to open questions about the more general role of metal ions in functional evolution and divergence within enzyme superfamilies. Here, we present detailed mechanistic studies of the paraoxonase and arylesterase activities of MPH complexed with five different transition metal ions, and demonstrate that the hydrolysis reactions proceed via similar pathways and transition states. However, while it is possible to discern a clear structural origin for the selectivity between different substrates , the selectivity between different metal ions appears to lie instead in the distinct electrostatic properties of the metal ions themselves, which causes subtle changes in transition state geometries and metal–metal distances at the transition state rather than significant structural changes in the active site. While subtle, these differences can be significant for shaping the metal-ion-dependent activity patterns observed for this enzyme. This article is part of the themed issue ‘Multiscale modelling at the physics–chemistry–biology interface’.
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Barrozo, Alexandre, David Blaha-Nelson, Nicholas H. Williams, and Shina C. L. Kamerlin. "The effect of magnesium ions on triphosphate hydrolysis." Pure and Applied Chemistry 89, no. 6 (June 27, 2017): 715–27. http://dx.doi.org/10.1515/pac-2016-1125.
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AbstractThe role of metal ions in catalyzing phosphate ester hydrolysis has been the subject of much debate, both in terms of whether they change the transition state structure or mechanistic pathway. Understanding the impact of metal ions on these biologically critical reactions is central to improving our understanding of the role of metal ions in the numerous enzymes that facilitate them. In the present study, we have performed density functional theory studies of the mechanisms of methyl triphosphate and acetyl phosphate hydrolysis in aqueous solution to explore the competition between solvent- and substrate-assisted pathways, and examined the impact of Mg2+ on the energetics and transition state geometries. In both cases, we observe a clear preference for a more dissociative solvent-assisted transition state, which is not significantly changed by coordination of Mg2+. The effect of Mg2+ on the transition state geometries for the two pathways is minimal. While our calculations cannot rule out a substrate-assisted pathway as a possible solution for biological phosphate hydrolysis, they demonstrate that a significantly higher energy barrier needs to be overcome in the enzymatic reaction for this to be an energetically viable reaction pathway.
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da Silva, Antônio Carlos, S. C. Santos, and Sonia Regina Homem de Mello-Castanho. "Transition Metals in Glass Formation." Materials Science Forum 727-728 (August 2012): 1496–501. http://dx.doi.org/10.4028/www.scientific.net/msf.727-728.1496.
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The structure of silicate glasses gets its charge stability through SiO2, R2O3, R2+and R+groups arrangement. In these glassy structures, transition metals are usually used as dopants in small amounts. However, in soda-lime glass systems, transition metals can take part in the glassy network in larger quantities as secundary former or modifier, insted R2+groups, if the charge balance conditions are made favorable by R2O3groups additions. This paper studies transition metals (Cr, Ni, Fe, Cu, Zn, Pb, Ru) soda-lime-borosilicate glass network incorporation. This process was applied for many kinds of toxic metals containing vitrification waste. The glasses were obtaind by melt at temperature of 1300°C, and characterized by FT-IR and XRD techinics. The chemical stability was evaluated by hydrolytic attack test. The glasses showed a high chemistry and environmental stability like the soda-lime glass.Keywords: glass structure, electroplating waste, e-waste, nanowaste.
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Lemanowicz, Joanna, and Agata Bartkowiak. "Diagnosis of the Content of Selected Heavy Metals in the Soils of the Pałuki Region Against their Enzymatic Activity." Archives of Environmental Protection 39, no. 3 (September 1, 2013): 23–32. http://dx.doi.org/10.2478/aep-2013-0026.
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Abstract The paper presents the research results for the soils sampled from the area located in the eastern part of the Chodzieskie Lakes, between the Middle Noteć River Valley and the Wełna River Valley, the right tributary of the Warta River. The research involved 7 soil samples from the surface horizons, allocated to the cultivation of various plant species (cereals and vegetable crops). The following were determined in the soil material: the content of phytoavailable forms of selected heavy metals Zn, Cu, Pb, Ni, Fe and Mn, active and available to plants phosphorus against the activity of selected oxydo-reduction and hydrolytic enzymes. The soil under the vegetable crops showed a very high richness in phosphorus available to plants, which must have been related to an intensive fertilisation. There were identified relatively low contents of the available forms of the heavy metals investigated, the fact that points to their natural content in soil, which triggered the inhibition of neither the oxydo-reduction nor hydrolytic enzymes.
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Abouhmad, Adel, Ahmed H. Korany, Carl Grey, Tarek Dishisha, and Rajni Hatti-Kaul. "Exploring the Enzymatic and Antibacterial Activities of Novel Mycobacteriophage Lysin B Enzymes." International Journal of Molecular Sciences 21, no. 9 (April 30, 2020): 3176. http://dx.doi.org/10.3390/ijms21093176.
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Mycobacteriophages possess different sets of lytic enzymes for disruption of the complex cell envelope of the mycobacteria host cells and release of the viral progeny. Lysin B (LysB) enzymes are mycolylarabinogalactan esterases that cleave the ester bond between the arabinogalactan and mycolic acids in the mycolylarabinogalactan-peptidoglycan (mAGP) complex in the cell envelope of mycobacteria. In the present study, four LysB enzymes were produced recombinantly and characterized with respect to their enzymatic and antibacterial activities. Examination of the kinetic parameters for the hydrolysis of para-nitrophenyl ester substrates, shows LysB-His6 enzymes to be active against a range of substrates (C4–C16), with a catalytic preference towards p-nitrophenyl laurate (C12). With p-nitrophenyl butyrate as substrate, LysB-His6 enzymes showed highest activity at 37 °C. LysB-His6 enzymes also hydrolyzed different Tween substrates with highest activity against Tween 20 and 80. Metal ions like Ca2+ and Mn2+ enhanced the enzymatic activity of LysB-His6 enzymes, while transition metal ions like Zn2+ and Cu2+ inhibited the enzymatic activity. The mycolylarabinogalactan esterase activity of LysB-His6 enzymes against mAGP complex was confirmed by LC-MS. LysB-His6 enzymes showed marginal antibacterial activity when tested alone against Mycobacterium smegmatis, however a synergetic activity was noticed when combined with outer membrane permealizers. These results confirm that LysB enzymes are lipolytic enzymes with potential application as antimycobacterials.
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Sanyal, Sankar N, Gurdeep Singh, and Shailender S Kanwar. "Thermotropic Lipid Phase Transition and the Behavior of Hydrolytic Enzymes in the Kidney Cortex Brush Border Membrane." Chemistry & Biodiversity 3, no. 10 (October 2006): 1102–15. http://dx.doi.org/10.1002/cbdv.200690112.
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Olin, Magnus, Jonas Carlsson, and Leif Bülow. "Quantitation of Transition Metals Using Genetically Engineered Enzymes Carrying Polyhistidine Tails." Analytical Letters 28, no. 7 (May 1995): 1159–71. http://dx.doi.org/10.1080/00032719508000335.
Full textDissertations / Theses on the topic "Transition metals; Hydrolytic enzymes"
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Allen, Joanne Victoria. "Recent advances in asymmetric catalysis." Thesis, Loughborough University, 1995. https://dspace.lboro.ac.uk/2134/27574.
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CHAPTER ONE reviews the literature, discussing aspects of transition metal mediated asymmetric catalysis in the presence of enantiomerically pure ligands. CHAPTER TWO discusses the asymmetric addition of dialkyl-zinc reagents to aromatic aldehydes. The work presented is particularly concerned with the design and construction of enantiomerically pure oxazoline ligands tethered to alcohols These ligands have proved effective in the acceleration of the alkylation reaction and are able to influence good levels of asymmetric induction in the resultant secondary alcohol products CHAPTER THREE examines the electronic (and steric) effects of enantiomerically pure oxazoline ligands for the palladium catalysed allylic substitution reaction. Using ligands possessing two electronically different donor atoms, it is possible to create electronic distortion upon the intermediate allyl complex. In doing so it is possible to direct nucleophilic addition to one carbon centre preferentially to the other, resulting in asymmetric induction. Manipulation of these ligands enables control in the extent of electron distortion inflicted upon the allyl complex and consequently influences the levels of enantioselectivity observed. CHAPTER FOUR investigates the ability of hydrolytic enzymes to kinetically resolve a series of allylic acetates, under varying conditions. Lipases appeared superior to esterases for the substrates employed. In particular cis-3-acetoxy-5-carbomethoxycyclohexene was smoothly resolved m high yield and enantioselectivity. CHAPTER FIVE reports on the potentiality of a dynamic resolution of allylic acetates, using hydrolytic enzymes in the presence of a palladium catalyst. A proposed mechanism is discussed. Initial results are promising, however, the sensitivity of the reaction is realised and optimisation of conditions still needs to be addressed.
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Turner, Nigel Arthur. "Studies on the molybdenum centre in enzymes." Thesis, University of Sussex, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284106.
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Dinescu, Adriana Cundari Thomas R. "Metals in chemistry and biology computational chemistry studies /." [Denton, Tex.] : University of North Texas, 2007. http://digital.library.unt.edu/permalink/meta-dc-3678.
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Dinescu, Adriana. "Metals in Chemistry and Biology: Computational Chemistry Studies." Thesis, University of North Texas, 2007. https://digital.library.unt.edu/ark:/67531/metadc3678/.
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Numerous enzymatic reactions are controlled by the chemistry of metallic ions. This dissertation investigates the electronic properties of three transition metal (copper, chromium, and nickel) complexes and describes modeling studies performed on glutathione synthetase. (1) Copper nitrene complexes were computationally characterized, as these complexes have yet to be experimentally isolated. (2) Multireference calculations were carried out on a symmetric C2v chromium dimer derived from the crystal structure of the [(tBu3SiO)Cr(µ-OSitBu3)]2 complex. (3) The T-shaped geometry of a three-coordinate β-diketiminate nickel(I) complex with a CO ligand was compared and contrasted with isoelectronic and isosteric copper(II) complexes. (4) Glutathione synthetase (GS), an enzyme that belongs to the ATP-grasp superfamily, catalyzes the (Mg, ATP)-dependent biosynthesis of glutathione (GSH) from γ-glutamylcysteine and glycine. The free and reactant forms of human GS (wild-type and glycine mutants) were modeled computationally by employing molecular dynamics simulations, as these currently have not been structurally characterized.
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Güell, Serra Mireia. "Theoretical studies of systems of biochemical interest containing Fe and Cu transition metals." Doctoral thesis, Universitat de Girona, 2009. http://hdl.handle.net/10803/7941.
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La presència de la química teòrica i computacional està augmentant en quasi tots els camps de la recerca en química. Els càlculs teòrics poden ajudar a entendre millor l'estructura, les propietats i la reactivitat de compostos metàl·lics d'àrees tan diferents com la química inorgànica, organometàl·lica i bioinorgànica. No obstant això, és imprescindible utilitzar la metodologia adequada per obtenir resultats teòrics fiables. Els estudis d'aquesta tesi es poden dividir en dos grups diferents. El primer grup inclou l'estudi teòric del mecanisme de reacció de diversos sistemes que contenen coure i tenen diferents estructures Cun-O2. Aquests estudies s'han dut a terme amb l'objectiu de profunditzar en la natura dels processos oxidants químics i biològics promoguts per sistemes que contenen coure. En la segona part de la tesi, s'estudia la fiabilitat de diferents tècniques utilitzades per estudiar l'estructura electrònica i la reactivitat de sistemes que contenen coure, ferro i altres metalls de transició.The presence of computational and theoretical chemistry is increasing in chemical research in nearly all fields. Theoretical calculations can help to better explain structure, properties, and reactivity in metallic compounds, in such diverse areas as inorganic, organometallic and bioinorganic chemistry. However, it is essential to use the suitable methodology in order to obtain reliable theoretical results. The studies of this Thesis can be divided into two different groups. The first group includes the theoretical study of the reaction mechanism of several copper-containing systems with different Cun-O2 structures. These studies are carried out with the aim of providing some insight into the nature of the chemical and biological copper-promoted oxidative processes with 1:1 and 2:1 Cu(I)/O2-derived species. In the second part of this Thesis the reliability of different theoretical approaches used to study the electronic structure and reactivity of systems containing copper, iron or other transition metals is evaluated.
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Selvi, A. Tamil. "Metallo-β-Lactamase, Phosphotriesterase And Their Functional Mimics." Thesis, 2009. http://hdl.handle.net/2005/994.
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Metallohydrolases with dinuclear-zinc active sites perform many important biological hydrolytic reactions on a variety of substrates. In this regard, metallo-β-lactamases (mβ1, class B) represent a unique subset of zine hydrolases that hydrolyze the β-lactam ring in several antibiotics. The antibiotic resistance that results from this hydrolysis is becoming an increased threat for the clinical community. These metalloenzymes can hydrolyze a wide range of β-lactam substrates, such as cephamycins and imipenem that are generally resistant t the serine-containing β-lactamases. Therefore, the clinical application of the entire range of antibiotics is severely compromised in bacteria that produce mβls. Due to the lack of information on the mechanism of mβls, to-date, no clinically known inhibitors is there for mβls. In this present study, we synthesized several mono and dizinc complexes as models for the mβls and investigated the differences in their hydrolytic properties. This study supports the assumption that the second zinc in the dinuclear enzymes does not directly involve in the catalysis, but may orient the substrates for hydrolysis and the basic amino acid residues such as Asp and His may activate the zinc-bound water molecules, fulfilling the role of the second zinc in the mononuclear enzymes.
The effect of various side chains on the hydrolysis of some commonly used cephalosporin antibiotics by mβl from B.cereus is described. It is shown that the cephalosporins having heterocyclic thiol side chains are more resistance to mβl-mediated hydrolysis than the antibiotics that do not have such side chains. This is partly due to the inhibition of enzyme activity by the thiol moieties eliminated during the hydrolysis. It is also observed that the heterocyclic side chains in pure form inhibit the lactamase activity of mβl as well as its synthetic mimics. The mode of binding of these heterocyclic side chains to the zinc has been analyzed from the crystal structure of the tetranuclear zinc complexes. The theoretical studies suggest that the eliminated heterocyclic thiols undergo a rapid tautomerism to produce the corresponding thiones. These thiones are found to irreversibly inhibit the LPO-catalyzed iodination reaction. The reaction of various thiones with I2 leads to the formation of thione-iodine complexes similar to that of the most commonly used antithyroid drug methimazole(MMI). These observations suggest that some of the latest generation of antibiotics may show negative effects on thyroid gland upon hydrolysis.
Synthetic organophosphorus compounds have been used extensively as pesticides and petroleum additives. These compounds are very toxic to mammals and their widespread use in agriculture leads to serious environmental problems. Therfore, degradation of organophosphorus trimesters and remediation of associated contaminated sites are of worldwide concern. In this regards, the bacterial phsophotriesterase (PTE) enzyme plays an important role in degrading a wide range of organophosphorus esters and the active side of PTE has been shown to be very similar to that of mβl. This identification prompted us to check the hydrolysis of phosphotriesters by the mβl and its mimics. It has been observed that the dinuclear zine(II) complexes that do not allow a strong binding of phosphodiestes would be a better PTE mimics.
Books on the topic "Transition metals; Hydrolytic enzymes"
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O, Hill H. A., Sadler P. J, and Thompson A. J, eds. Metal sites in proteins and models: Redox centres. Berlin: Springer, 1998.
Find full textBook chapters on the topic "Transition metals; Hydrolytic enzymes"
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Marino, Tiziana, Mario Prejanò, and Nino Russo. "How Metal Coordination in the Ca-, Ce-, and Eu-Containing Methanol Dehydrogenase Enzymes Can Influence the Catalysis: A Theoretical Point of View." In Transition Metals in Coordination Environments, 487–501. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-11714-6_16.
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Valentine, Joan Selverstone, Judith N. Burstyn, and Lawrence D. Margerum. "Mechanisms of Dioxygen Activation in Metal-Containing Monooxygenases: Enzymes and Model Systems." In Oxygen Complexes and Oxygen Activation by Transition Metals, 175–87. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-0955-0_13.
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Doraiswamy, L. K. "Homogeneous Catalysis." In Organic Synthesis Engineering. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780195096897.003.0014.
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Catalysis by soluble complexes of transition metals is a rapidly gaining mode of catalysis in organic synthesis. These metals form bonds with one or more carbons in an organic reactant resulting in complexes that are known as organometallic complexes. Catalysis by these complexes is often referred to as homogeneous catalysis. Among the important applications of homogeneous catalysis in organic synthesis are isomerization of olefins; hydrogenation of olefins (carried out using Wilkinson type catalysts); oligomerization; hydroformylation of olefins to aldehydes with CO and H2 (the oxo process); carbonylation of unsaturated hydrocarbons and alcohols with CO (and coreactants such as water); oxidation of olefins to aldehydes, ketones, and alkenyl esters (Wacker process); and metathesis of olefins (a novel kind of disproportionation). Enantioselective catalysis that rivals enzymes in selectivity is a major development in homogeneous catalysis. As a result, many earlier processes in the pharmaceutical and perfumery industries are being replaced by more elegant syntheses using soluble catalysts in which “handedness” is introduced in the critical step of the process, thus avoiding the costly separation of racemic mixtures. In view of its importance in organic synthesis, enantioselective (or asymmetric) catalysis was briefly introduced in Chapter 6 and is again considered as a powerful synthetic tool in Chapter 9. This chapter is concerned with the use in general of homogeneous catalysis in organic synthesis (including asymmetric synthesis). Among the several books and reviews written on the subject, the following may be mentioned: Halpern (1975, 1982), Bau et al. (1978), Parshall (1980), Masters (1981), Collman and Hegedus (1980), Eby and Singleton (1983), Chaudhari (1984), Davidson (1984), Kegley and Pinhas (1986), Collman et al. (1987), Parshall and Nugent (1988), Noyori and Kitamura (1989), Parshall and Ittel (1992), Gates (1992), Chan (1993), Akutagawa (1995). Gas (or liquid)-phase reactions on solid catalysts are among the most common industrial reactions. However, homogeneous catalysis is rapidly catching up. Excluding applications in petroleum refining, the dollar value of organic chemicals produced worldwide by homogeneous catalysis (more than $35 billion) is quite impressive compared to that by heterogeneous catalysis (more than $45 billion). Attempts are now under way to find an integrated approach to homogeneous and heterogeneous catalyses (Moulijn et al., 1993).