Redox Enzymes

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Expansion of the enzymatic repertoire of the CAZy database to integrate auxiliary redox enzymes

Expansion of the enzymatic repertoire of the CAZy database to integrate auxiliary redox enzymes

Cell wall carbohydrates and lignin co-occur in all land plants and are intimately interconnected and covalently cross-linked. We therefore believe that a strict boundary between (hemi)cellulolysis and ligninolysis is perhaps artifi- cial, since functional inference often hinges on the choice of the substrates and analytical methods used in biochem- ical assays. Moreover, several publications have evidenced a concerted action of specific enzymes able to act on both carbohydrates and lignin [13,21]. In the post-genomic era, where the quest for efficient enzymes for plant cell wall de- construction has become a major research subject, the sim- ultaneous identification of CAZymes and lignin-degrading enzymes is required to describe the full enzymatic reper- toire necessary for plant cell wall deconstruction. Here, we describe the integration of a novel class in the CAZy database. This novel category, broadly termed “Auxiliary Activities” groups together the families of LPMO and the families of redox enzymes involved in lignin breakdown. Like the traditional CAZy families, the new families are based on sequence similarity with one or several biochemically-characterized founding member(s), ensuring that members of a given family share the same three- dimensional structure. Combined with the traditional CAZy families, this addition allows a complete description of the main actors involved in the degradation of all plant cell wall components. Like all enzyme classes in CAZy, the novel class features a hierarchical division in families and, where relevant, clans and subfamilies, all freely accessible at http://www.cazy.org.
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Disulfide Bond Formation at the C Termini of Vaccinia Virus A26 and A27 Proteins Does Not Require Viral Redox Enzymes and Suppresses Glycosaminoglycan-Mediated Cell Fusion

Disulfide Bond Formation at the C Termini of Vaccinia Virus A26 and A27 Proteins Does Not Require Viral Redox Enzymes and Suppresses Glycosaminoglycan-Mediated Cell Fusion

In eukaryotic yeasts and mammalian cells, the redox regu- lation is highly compartmentalized, and accumulative knowl- edge revealed that each of the major compartments have unique redox characteristics (15). Among the different cellular compartments, cytosol is highly reduced, whereas the endo- plasmic reticulum (ER) and the secretory pathway contain proteins with oxidative functions, including Ero-1 and PDI, that introduce disulfides into proteins during refolding and export processes (15, 46). On the other hand, it has been suggested that some vaccinia virus membrane proteins formed disulfide bonds in the cytosol of virus-infected cells (30) and that vaccinia virus contains a complete redox pathway, includ- ing E10, G4, and A2.5 proteins for forming cytoplasmic disul- fide bonds on viral proteins (43, 45). Based on these published results, we originally expected that A26 and A27 proteins would be similar to L1 protein in the need of viral redox enzymes for disulfide formation. In contrast, the 70-/90-kDa protein complexes and some oxidized forms of L1 protein still formed in the infected cells when no G4 or E10 protein was expressed. The data thus suggested that, while the repression of viral redox enzymes significantly affects virus growth, these enzymes are not required for the disulfide bond between A26 and A27 proteins. This conclusion is supported by our data using transiently transfected 293T cells in which A26 and A27 proteins readily formed 70-/90-kDa complexes, showing that the viral redox system is dispensable for A26-A27 disulfide bond formation. Interestingly, Rodriguez et al. had con- structed a chimeric molecule of vaccinia virus A27 fused with human immunodeficiency virus Env and found that this mol- ecule was partially glycosylated and could be expressed on the cell surface, suggesting that the chimera molecule has passed through the ER lumen for limited glycosylation (39). The chi- mera A27-Env molecule contains the N-terminal 110 aa of A27 sequences, implying that the A27 N-terminal region could serve as a signal peptide for targeting the chimera molecule to the ER/secretory pathway. Besides, A17 and A27 proteins, when transfected into 293T cells, formed a complex and trans- ported to the cell surface in 293T cells (27), providing another example in which viral membrane protein complexes were formed and exported, most likely using the cellular ER/secre- tory pathway. Alternatively, although the eukaryotic cytosolic environment often is considered highly reduced, the slow oxi- dation of newly synthesized cytosolic proteins occurred and was correlated with the oxidized glutathione/glutathione ratio in the cytosol (33). Therefore, we cannot totally rule out a cytoplasmic contribution to A26-A27 protein disulfide bond formation.
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The electrochemistry of redox enzymes

The electrochemistry of redox enzymes

6.6, REAGENTLESS MEMBRANE ELECTRODES In this section the responses of membrane electrodes constructed using ferrocene carboxylic acid modified glucose oxidase GOD is described.. The kine[r]

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Electrochemical studies of modified redox enzymes

Electrochemical studies of modified redox enzymes

the enzyme with some reagents, such as urea, enables one to gain some form of access to the active site of the enzyme, the distance between the active site and the electrode surface is usually too great for the direct exchange of electrons with the electrode. Studies by Marcus and Sutin (29) have demonstrated clearly the effect of distance on the rate of electron transfer. They concluded that the rate o f electron transfer decreases exponentially with the distance between the reactants (section 1.2). Thus the rational for modifying an enzyme by attaching a number of redox mediators to the amino acid residues on the polypeptide backbone is that in this way we add some electron-transfer relays or "stepping stones" to allow the electron to transfer via several short steps instead of one long "jump" (figure 3.1). An excellent review of the criteria for covalent modification of glucose oxidase and D-amino acid oxidase can be found in the PhD thesis by R.G. Whitaker 020)
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Nigella sativa fixed and essential oil modulates glutathione redox enzymes in potassium bromate induced oxidative stress

Nigella sativa fixed and essential oil modulates glutathione redox enzymes in potassium bromate induced oxidative stress

Conclusive approach drawn from this efficacy study is, Nigella sativa fixed and essential oils hold potential to improve the antioxidant status and decrease antioxi- dant damage significantly in potassium bromate in- duced oxidative stressed rats. The oxidative stress and ROS induced negative changes in enzyme expressions but experimental diets modulated hepatic enzymes and immune system including GR, Gpx, GST, MPO, and xanthine oxidase positively. However, there is need to conduct further trials in other types of ani- mal modeling to validate the findings.

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The impact of enzyme orientation and electrode topology on the catalytic activity of adsorbed redox enzymes

The impact of enzyme orientation and electrode topology on the catalytic activity of adsorbed redox enzymes

platform for fundamental research and have application in biosensing and biofuel cells [4-6]. In order for PFE, biosensors or biofuel cells to achieve their optimal efficacy, the interfacial ET between the electrode and enzyme has to be fast compared to the enzyme’s turnover. In turn, this requires the enzyme to be oriented with its electron-entry site towards the surface or, alternatively, the redox site of the enzyme can be ‘wired’ to the electrode [7, 8]. The orientation of enzymes physisorbed (i.e., non-covalently bound) on an electrode depends on many factors, including the charge of the electrode. For over two decades, a common and very successful approach to control the properties of a gold interface has been to modify it with self-assembled monolayers (SAMs). The influence of different SAMs on the
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Rhodium and Its Compounds in Amperometric Biosensors Based on Redox Enzymes

Rhodium and Its Compounds in Amperometric Biosensors Based on Redox Enzymes

phenylpyridine)rhodium(III) dimer (CFPRD) were tested as mediators/catalysts of electron transfer in electrochemical biosensors for the determination of glucose. Measurements were realized using flow injection system and screen-printed carbon electrodes containing glucose oxidase as a model redox enzyme. From all of the above-mentioned matters, a sensor with RhO 2 was found the best exhibiting a

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Enzymes for industrial applications

Enzymes for industrial applications

Résumé – Développement d’enzymes pour des applications industrielles. Protéus est une société de biotechnologie spécialisée dans la découverte, l’ingénierie et la production d’enzymes pour des applications industrielles, ainsi que dans le développement de bioprocédés innovants mettant en œuvre ces enzymes. Protéus est une fi liale du groupe PCAS actif dans le développement, la fabrication et la commercialisation de produits de chimie fine et de spécialités. Les enzymes permettent de produire de nouvelles molécules dans un contexte de chimie verte (économie d’atomes, conditions douces de mise en œuvre, amélioration de la sélectivité, réduction de la toxicité) et d’envisager des fonctionnalisations uniques qui sont difficiles à obtenir par des moyens chimiques classiques. Des exemples de réalisation seront présentés avec notamment le criblage de notre toolbox enzymatique, l’ingénierie de la lipase issue de Candida antarctica et la fonctionnalisation de liaisons CH non activées.
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Coordination and Redox Chemistries of the Rare Earths Within Redox Active Nitroxide Ligand Frameworks

Coordination and Redox Chemistries of the Rare Earths Within Redox Active Nitroxide Ligand Frameworks

Nitroxides are important compounds in a wide variety of chemical disciplines, ranging from organic to inorganic to medicinal and materials chemistries, due to their stabilities in multiple redox forms. [1] In their neutral state, these compounds exist as π-radicals with spin density primarily located on the N–O moiety. These radicals can either be oxidized to their cationic oxoammonium forms or reduced to the anionic nitroxides, both of which have closed shell electronic configurations (Figure 2.1.1). [2] The electrochemical potentials for these transformations fall into chemically accessible ranges, which makes them desirable reagents for the synthetic chemist. For example, derivatives of the well-known nitroxide, 2,2,6,6- tetramethylpiperidine-N-oxyl (TEMPO), have been used in organic chemistry as catalysts in the oxidation of primary and secondary alcohols to aldehydes and ketones. TEMPO can also be activated towards oxidation chemistry through coordination to a Lewis acid such as Cu(II), [1a-c] Fe(III), [1d] and Al(III). [1d]
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Redox signaling in pathophysiology of hypertension

Redox signaling in pathophysiology of hypertension

Despite the fact that cells of different systems involved in the regulation of blood pressure perform different functions, the redox signaling is by and large very similar and unveil no apparent differences among these types of cells. NADPH oxidases are primary resources of ROS in the endothelial cells, vascular smooth muscle cells, cardiomyocytes, cells of kidneys, as well as cardiovascular neurons (regions such as the circumventricular organs, paraventricular nucleus of the hypothalamus, nucleus tractus solitarii and RVLM) in the brain [10,12,21,42-44]. Ang II is important activator of NADPH oxidases and stimulator of ROS production in all types of cells [20,42-46]. Production of ROS is stimulated by shear and mechanical stress in the vascular smooth muscle cells and cardiomyocytes, respectively. In addition, MAPKs are re- sponsible for major effects of ROS such as proliferation, hypertrophy, and apoptosis in these cells [20,42,45-47]. The same signaling is also proposed to mediate the in- crease in sympathetic nerve activity, vasopressin release and drinking behavior induced by Ang II (Table 1).
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NQO1 dependent redox cycling of idebenone : effects on cellular redox potential and energy levels

NQO1 dependent redox cycling of idebenone : effects on cellular redox potential and energy levels

chemical class containing a quinoid ring system [reviewed by 1,2] as pharmacophore. Despite significant differences between quinones, the quinoid system is the dominant feature that causes all of them to be electrophiles, oxidants and colored. However, already minor variances in their chemical and physicochemical properties lead to extensive differences in their biological and pharmacological effects. Enzymes involved in cellular quinone metabolism catalyze mainly two different redox reactions. For example, NADPH:cytochrome P450 reductase can generate semiquinones by incomplete, one-electron reduction [1,2]. Since semiquinones can react with molecular oxygen to generate reactive oxygen species (ROS), this process can lead to oxidative damage of cellular macromolecules, toxicity and mutagenicity [1,2]. In contrast, NAD(P)H:quinone oxidoreductases (NQOs) are cytosolic flavoproteins that compete with P450 reductase and catalyze the reduction of highly reactive quinones and their derivates by complete, two-electron reduction [2]. This results in the formation of relatively stable hydroquinones, often also referred to as quinols, and therefore avoids the formation of ROS. Thus, NQOs are considered key detoxifying enzymes which
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Two NAD-linked redox shuttles maintain the peroxisomal redox balance in Saccharomyces cerevisiae

Two NAD-linked redox shuttles maintain the peroxisomal redox balance in Saccharomyces cerevisiae

is restored and secondly, in mdh3/gpd1Δ cells the substrate/product ratio for Lys1p is 80 fold increased. Why S. cerevisiae contains two distinct parallel pathways to reoxidise intraperoxisomal NADH is still unclear. The presence of multiple peroxisomal redox shuttles appears to be widespread throughout the eukaryotic king- dom. For instance, in addition to glycerol 3-phosphate dehydrogenase, mammalian liver peroxisomes contain malate dehydrogenase and lactate dehydrogenase that have been suggested to act as redox shuttles. However, evi- dence for a role in vivo is lacking 21–24 . T. brucei, in its mammalian host, relies exclusively on glycolysis for energy
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1.5 Enzymes

1.5 Enzymes

• Spiders and flies secrete an enzyme soup into or on their food. In spiders, this is injected into the prey's body. The enzymes digest the prey's body contents and the spider sucks up the resulting digested food. • Saprophytic fungi also secrete enzymes through their

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Enzymes Boardworks

Enzymes Boardworks

Enzymes speed up reactions by lowering the activation energy (E a ) of a reaction.. The activation energy is the energy needed to start a reaction.[r]

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Redox Poerpoint 2017.ppt

Redox Poerpoint 2017.ppt

 Oxidizing agent decreases its oxidation number Oxidizing agent decreases its oxidation number.. In reaction with metals, nonmetals In reaction with metals, nonmetals. are always oxidi[r]

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energy & enzymes ppt

energy & enzymes ppt

• Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions, typically using the energy stored in ATP molecules... 5.12 ATP drives cellular work [r]

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Redox electrode materials for supercapatteries

Redox electrode materials for supercapatteries

mentioned conducting polymers. The most commonly used conducting polymers for charge storage purposes are polypyrrole (PPy), polyaniline (PAn) and poly(3,4-ethylenedioxythiophene) (PEDOT). They are in a good balance position between polymer plasticity and electronic conductivity. In common conditions, the characteristics of redox electrode materials will greatly affect the performance of the supercapattery. Composites comprising redox materials and carbon based skeleton materials have been considered to be promising for improving the performance of charge storage in supercapattery. In the recent decade, both the metal oxides and conducting polymers have been successfully composited with CNTs and graphenes. The redox materials in such composites still play an important role in the charge storage of a supercapattery cell.
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ph, redox and I.S.E. electrodes

ph, redox and I.S.E. electrodes

Gel or liquid electrolyte Electrolyte CRISOLYT Membrane resistant to HF Ceramic diaphragm PTFE diaphragm Flat membrane Sample Encapsulated reference element Solid state membrane, c[r]

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textbook redox part 2

textbook redox part 2

voltaic cell.. a) The anode in an electroplating process is normally a high purity form of the metal to be plated. There are very few such nickel products. An inert electrode, such as p[r]

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textbook redox part 1

textbook redox part 1

Silver reacts in a single replacement reaction with 75 mL of 0.25 mol/L AuCl3(aq). What mass of reducing agent is used?.[r]

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