scholarly journals Cytochrome c Reduction by H2S Potentiates Sulfide Signaling

2018 ◽  
Vol 13 (8) ◽  
pp. 2300-2307 ◽  
Author(s):  
Victor Vitvitsky ◽  
Jan Lj. Miljkovic ◽  
Trever Bostelaar ◽  
Bikash Adhikari ◽  
Pramod K. Yadav ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Reduction

Experimental Studies and Computational Modeling on Cytochrome C Reduction by Quercetin: the role of oxidability and binding affinity

2021 ◽  
pp. 130995
Author(s):  
Gabriel Zazeri ◽  
Ana Paula Ribeiro Povinelli ◽  
Nathalia M. Pavan ◽  
Daniella Romano de Carvalho ◽  
Carmen Lúcia Cardoso ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Computational Modeling ◽  
Binding Affinity ◽  
Experimental Studies ◽  
Cytochrome C Reduction

scholarly journals The importance of the interdomain hinge in intramolecular electron transfer in flavocytochrome b2

1993 ◽  
Vol 291 (1) ◽  
pp. 89-94 ◽  
Author(s):  
P White ◽  
F D C Manson ◽  
C E Brunt ◽  
S K Chapman ◽  
G A Reid
Keyword(s):  
Electron Transfer ◽  
Steady State ◽  
Cytochrome C ◽  
Kinetic Properties ◽  
Stopped Flow ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Cytochrome C Reductase ◽  
Flavocytochrome B2 ◽  
Cytochrome C Reduction

The two distinct domains of flavocytochrome b2 (L-lactate:cytochrome c oxidoreductase) are connected by a typical hinge peptide. The amino acid sequence of this interdomain hinge is dramatically different in flavocytochromes b2 from Saccharomyces cerevisiae and Hansenula anomala. This difference in the hinge is believed to contribute to the difference in kinetic properties between the two enzymes. To probe the importance of the hinge, an interspecies hybrid enzyme has been constructed comprising the bulk of the S. cerevisiae enzyme but containing the H. anomala flavocytochrome b2 hinge. The kinetic properties of this ‘hinge-swap’ enzyme have been investigated by steady-state and stopped-flow methods. The hinge-swap enzyme remains a good lactate dehydrogenase as is evident from steady-state experiments with ferricyanide as acceptor (only 3-fold less active than wild-type enzyme) and stopped-flow experiments monitoring flavin reduction (2.5-fold slower than in wild-type enzyme). The major effect of the hinge-swap mutation is to lower dramatically the enzyme's effectiveness as a cytochrome c reductase; kcat. for cytochrome c reduction falls by more than 100-fold, from 207 +/- 10 s-1 (25 degrees C, pH 7.5) in the wild-type enzyme to 1.62 +/- 0.41 s-1 in the mutant enzyme. This fall in cytochrome c reductase activity results from poor interdomain electron transfer between the FMN and haem groups. This can be demonstrated by the fact that the kcat. for haem reduction in the hinge-swap enzyme (measured by the stopped-flow method) has a value of 1.61 +/- 0.42 s-1, identical with the value for cytochrome c reduction and some 300-fold lower than the value for the wild-type enzyme. From these and other kinetic parameters, including kinetic isotope effects with [2-2H]lactate, we conclude that the hinge plays a crucial role in allowing efficient electron transfer between the two domains of flavocytochrome b2.

scholarly journals Macrophage variants in oxygen metabolism.

1980 ◽  
Vol 152 (4) ◽  
pp. 808-822 ◽  
Author(s):  
G Damiani ◽  
C Kiyotaki ◽  
W Soeller ◽  
M Sasada ◽  
J Peisach ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Cytochrome C ◽  
Superoxide Anion ◽  
Oxygen Metabolism ◽  
Hexose Monophosphate ◽  
Phagocytic Cells ◽  
Form Complex ◽  
Hexose Monophosphate Shunt ◽  
Cytochrome C Reduction ◽  
Generate Superoxide Anion

Whereas phagocytic cells from normal individuals have the capacity to kill ingested bacteria and parasites, those from patients with several uncommon genetic deficiency diseases are known to be defective in bactericidal activity. Studies on neutrophils of these patients have revealed fundamental defects in their ability to reduce molecular oxygen and metabolize it to superoxide anion, hydrogen peroxide, and oxygen radicals. In the present experiments, we describe a clone of a continuous murine macrophage-like cell line, J774.16, that, upon appropriate stimulation, activates the hexose monophosphate shunt, and produces superoxide anion and hydrogen peroxide. With nitroblue tetrazolium to select against cells capable of being stimulated by phorbol myristate acetate to reduce the dye to polymer--formazan--which is toxic fot cells, we have selected for variants that are defective in oxygen metabolism. Four of these subclones have been characterized and found to be lacking in the ability (a) to generate superoxide anion, as measured by cytochrome c reduction; (b) to produce hydrogen peroxide, as measured by the ability to form complex I with cytochrome c peroxidase; and (c) to be stimulated to oxidize glucose via the hexose monophosphate shunt. These variants appear to represent a useful model for studying the molecular basis for macrophage cytocidal activity.

Decavanadate interacts with microsomal NADH oxidation system and enhances cytochrome c reduction

2006 ◽  
Vol 281 (1-2) ◽  
pp. 139-144 ◽  
Author(s):  
T. Ramasarma ◽  
Aparna V. S. Rao
Keyword(s):  
Cytochrome C ◽  
Nadh Oxidation ◽  
Cytochrome C Reduction ◽  
Oxidation System

scholarly journals The steady state kinetics of the NADH-dependent nitrite reductase from Escherichia coli K12. The reduction of single-electron acceptors

1982 ◽  
Vol 203 (2) ◽  
pp. 505-510 ◽  
Author(s):  
R H Jackson ◽  
J A Cole ◽  
A Cornish-Bowden
Keyword(s):  
Escherichia Coli ◽  
Cytochrome C ◽  
Nitrite Reductase ◽  
Maximum Velocity ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Steady State Kinetics ◽  
Cytochrome C Reduction ◽  
Pattern Of Variation ◽  
Rate Limiting

The kinetic characteristics of the diaphorase activities associated with the NADH-dependent nitrite reductase (EC 1.6.6.4) from Escherichia coli have been determined. The values of the apparent maximum velocity are similar for the reduction of Fe(CN)6(3)-and mammalian cytochrome c by NADH. These reactions may therefore have the same rate-limiting step. NAD+ activates NADH-dependent reduction of cytochrome c, and the apparent maximum velocity for this substrate increases more sharply with the concentration of NAD+ than for hydroxylamine. The simplest explanation is that NAD+ activation of hydroxylamine reduction derives solely from activation of steps involved in the reduction of cytochrome c, a flavin-mediated reaction, but these steps are only partly rate-limiting for the reduction of hydroxylamine. At 0.5 mM-NAD+, the apparent maximum velocity was 2.3 times higher for 0.1 mM-cytochrome c as substrate than for 100 mM-hydroxylamine, suggesting that the rate-limiting step during hydroxylamine reduction is a step that is not involved in cytochrome c reduction. A scheme is proposed that can account for the pattern of variation with [NAD+] of the Michaelis-Menten parameters for hydroxylamine and for NADH with hydroxylamine or cytochrome c as oxidized substrate.

Detection of superoxide anion released extracellularly by endothelial cells using cytochrome c reduction, ESR, fluorescence and lucigenin-enhanced chemiluminescence techniques

2000 ◽  
Vol 29 (5) ◽  
pp. 388-396 ◽  
Author(s):  
Marie-Aline Barbacanne ◽  
Jean-Pierre Souchard ◽  
Benoit Darblade ◽  
Jean-Pierre Iliou ◽  
Françoise Nepveu ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Cytochrome C ◽  
Superoxide Anion ◽  
Enhanced Chemiluminescence ◽  
Cytochrome C Reduction

Lipoxygenase-dependent superoxide release in skeletal muscle

2004 ◽  
Vol 97 (2) ◽  
pp. 661-668 ◽  
Author(s):  
Li Zuo ◽  
Fievos L. Christofi ◽  
Valerie P. Wright ◽  
Shengying Bao ◽  
Thomas L. Clanton
Keyword(s):  
Skeletal Muscle ◽  
Arachidonic Acid ◽  
Cytochrome C ◽  
Acid Metabolism ◽  
Arachidonic Acid Metabolism ◽  
Anion Channels ◽  
Cytochrome C Reduction ◽  
First Time ◽  
Cytochrome P 450 ◽  
Different Sources

Superoxide anion radical (O2•−) is released from skeletal muscle at rest and is particularly elevated during conditions of heat stress (42°C). Previous studies have shown that in isolated rat diaphragm O2•− release is not dependent on mitochondrial electron transport, reduced NADP oxidase activity, or the integrity of membrane anion channels. This study hypothesized that O2•− release, as measured by cytochrome c reduction, is linked to metabolism of arachidonic acid. Phospholipase A2 inhibition with manoalide significantly decreased O2•− release. In downstream pathways, neither the blockage of cyclooxygenase with indomethacin nor the inhibition of cytochrome P-450-dependent monooxygenase with SKF-525A decreased O2•− release. However, lipoxygenase (LOX) inhibition with general LOX blockers 5,8,11,14-eicosatetraynoic acid and cinnamyl-3,4-dihydroxy-α-cyanocinnamate greatly attenuated the signal. Furthermore, the specific 5-LOX inhibitor diethylcarbamazine also significantly decreased O2•− release. Immunohistochemistry localized 5- and 12-LOX to the cytosol and sarcolemma of muscle cells. Confocal studies, using the O2•−-sensitive fluorescent indicator hydroethidine, demonstrated that LOX inhibition had no significant influence on intracellular O2•− formation. When compared with the cytochrome c results, this indicates that intra- and extracellular O2•− must arise from different sources. These data show for the first time that arachidonic acid metabolism through LOX activity, is a major source of extracellular O2•− release in skeletal muscle.

scholarly journals CO oxidoreductase from Streptomyces strain G26 is a molybdenum hydroxylase

1988 ◽  
Vol 250 (2) ◽  
pp. 605-612 ◽  
Author(s):  
J M Bell ◽  
J Colby ◽  
E Williams
Keyword(s):  
Cytochrome C ◽  
Specific Activity ◽  
Superoxide Radicals ◽  
Native Enzyme ◽  
Benzyl Viologen ◽  
Streptomyces Strain ◽  
Cytochrome C Reduction ◽  
Acid Labile

CO oxidoreductase was purified to 95% homogeneity from crude mycelial extracts of Streptomyces G26. The purified preparation has a specific activity of 25.7 units/mg, a 13-fold improvement on crude soluble mycelial extracts. The native enzyme (Mr 282,000) is composed of non-identical subunits of Mr 110,000 and 33,000. It is a molybdenum hydroxylase containing 1.6 mol of FAD, 7.3 mol of Fe, 8.3 mol of acid-labile sulphide and 1.3 mol of Mo per mol of enzyme. Purified CO oxidoreductase catalyses the reduction of benzyl viologen, confirming the previously reported ability of this enzyme to interact with low-potential acceptors. Cytochrome c reduction cannot be accounted for entirely by non-enzymic reduction by superoxide radicals. NAD+ and NADP+ are not reduced, nor is clostridial ferredoxin.

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