Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.9.3.1 (cytochrome oxidase)
8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nitric oxide (NO) is a mobile, highly reactive signal molecule, and changes the expression of specific genes in effector cells. Under physiological conditions, NO reacts with molecular oxygen and with reactive oxygen species (ROS) to produce intermediates known as reactive nitrogen species (RNS). The production of NO and RNS in the cell is controlled by hormones, neurotransmitters, cytokines, and growth factors. Hence NO and its derivatives act as secondary paracrinous factors and transmit the signal from NO-producing to neighboring cells. Intracellular reception of NO and RNS is due to Src-related tyrosine protein kinases, G-protein Ras, cytochrome oxidase, and guanylate cyclase. Receptor proteins mostly contain heme, active thiol, or iron-sulfur groups, and are both on the plasma membrane and in internal cell compartments. Many of the NO receptors are the key components of cell regulatory systems controlling the transcription factors AP-1, HIF-1, NF-kappa B, and p53 and the expression of their target genes. A distinguishing feature of NO signaling is that changes in redox potential of the cell switch the NO receptor and, consequently, modify the NO effect. Depending on the ROS level, NO activates different signal transduction pathways to induce (or suppress) different gene sets. The data considered indicate that antioxidants may be used to directionally change the transcriptional response of the cell to NO.
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PMID:[Redox-dependent regulation of gene expression induced by nitric oxide]. 1504 36

Theoretical studies (B3LYP) on models of the active sites in Photosystem II (PSII) and cytochrome oxidase are discussed. The role of a tyrosyl radical in the O-O bond formation in PSII is investigated, as well as the tyrosyl radical formation. In cytochrome oxidase, mechanisms for O-O bond cleavage involving tyrosyl radical formation are investigated, together with possible roles for the tyrosine in the proton translocation.
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PMID:Important roles of tyrosines in photosystem II and cytochrome oxidase. 1510 15

Time-resolved spectroscopic studies in our laboratory of bovine heart cytochrome c oxidase dynamics are summarized. Intramolecular electron transfer was investigated upon photolysis of CO from the mixed-valence enzyme, by pulse radiolysis, and upon light-induced electron injection into the cytochrome c/cytochrome oxidase complex from a novel photoactivatable dye. The reduction of dioxygen to water was monitored by a gated multichannel analyzer using the CO flow-flash method or a synthetic caged dioxygen carrier. The pH dependence of the intermediate spectra suggests a mechanism of dioxygen reduction more complex than the conventional unidirectional sequential scheme. A branched model is proposed, in which one branch produces the P form and the other branch the F form. The rate of exchange between the two branches is pH-dependent. A cross-linked histidine-phenol was synthesized and characterized to explore the role of the cross-linked His-Tyr cofactor in the function of the enzyme. Time-resolved optical absorption spectra, EPR and FTIR spectra of the compound generated after UV photolysis indicated the presence of a radical residing primarily on the phenoxyl ring. The relevance of these results to cytochrome oxidase function is discussed.
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PMID:Time-resolved optical absorption studies of cytochrome oxidase dynamics. 1510 41

Tyrosine radicals play catalytic roles in essential metalloenzymes. Their properties--midpoint potential, stability...--or environment varies considerably from one enzyme to the other. To understand the origin of these properties, the redox tyrosines are studied by a number of spectroscopic techniques, including Fourier transform infrared (FTIR) and resonance Raman (RR) spectroscopy. An increasing number of vibrational data are reported for the (modified-) redox active tyrosines in ribonucleotide reductases, photosystem II, heme catalase and peroxidases, galactose and glyoxal oxidases, and cytochrome oxidase. The spectral markers for the tyrosinyl radicals have been recorded on models of (substituted) phenoxyl radicals, free or coordinated to metals. We review these vibrational data and present the correlations existing between the vibrational modes of the radicals and their properties and interactions formed with their environment: we present that the nu7a(C-O) mode of the radical, observed both by RR and FTIR spectroscopy at 1480-1515 cm(-1), is a sensitive marker of the hydrogen bonding status of (substituted)-phenoxyl and Tyr*, while the nu8a(C-C) mode may probe coordination of the Tyr* to a metal. For photosystem II, the information obtained by light-induced FTIR difference spectroscopy for the two redox tyrosines TyrD and TyrZ and their hydrogen bonding partners is discussed in comparison with those obtained by other spectroscopic methods.
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PMID:Vibrational spectroscopy to study the properties of redox-active tyrosines in photosystem II and other proteins. 1572 6

The cyc1 gene encoding the soluble dihemic cytochrome c CYC(41) from Acidithiobacillus ferrooxidans, an acidophilic organism, has been cloned and expressed in Escherichia coli as the host organism. The cytochrome was successfully produced and folded only in fermentative conditions: this allowed us to determine the molecular basis of the heme insertion at extreme pH. Point mutations at two sequence positions (E121 and Y63) were introduced near the two hemes in order to assign individual redox potentials to the hemes and to identify the interaction sites with the redox partners, rusticyanin and cytochrome oxidase. Characterization of mutants E121A, Y63A, and Y63F CYC(41) with biochemical and biophysical techniques were carried out. Substitution of tyrosine 63 by phenylalanine alters the environment of heme B. This result indicates that heme B has the lower redox potential. Interaction studies with the two physiological partners indicate that CYC(41) functions as an electron wire between RCy and cytochrome oxidase. A specific glutamate residue (E121) located near heme A is directly involved in the interaction with RCy. A docking analysis of CYC(41), RCy, and cytochrome oxidase allowed us to propose a model for the complex in agreement with our experimental data.
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PMID:Insight into molecular stability and physiological properties of the diheme cytochrome CYC41 from the acidophilic bacterium Acidithiobacillus ferrooxidans. 1585 Mar 81

Fourteen-day-old Phaseolus vulgaris L. cv. Top Crop (bush bean) plants were sprayed with the plant growth stimulant, potassium naphthenate (20 mm). Seven days after treatment the contents of glutamic acid dehydrogenase, glutamic-oxaloacetic transaminase, nitrate reductase, glutamine synthetase, and cytochrome oxidase in the trifoliate leaf blades of treated plants were significantly larger, and the specific activity of the last four was significantly greater. Potassium nephthenate (1 mum) in the assay solutions did not significantly alter the activity of these enzymes in the cell-free extracts of untreated plants. Leaf discs from treated plants did not incorporate (14)C-leucine into protein more actively. The protein content of leaves of treated plants was 15.3% greater, and the percentages of 16 individual amino acids in the hydrolysates of the proteins of control and treated plants showed numerous differences. The major changes were greater percentages of glutamic acid, glycine, and proline, and smaller values of arginine, lysine, tyrosine, and leucine in protein of treated plants. The content of ethanol-soluble (free) amino acids was greater by 7.5%. The principal changes in content of these acids were larger percentages of arginine and lysine, and smaller values for glutamic acid, serine, and proline in the leaves of potassium naphthenate-treated plants. The content of DNA, measured 1, 2, and 3 weeks after a foliar application of potassium naphthenate, was not significantly different from that of untreated plants, but the amount of RNA was significantly greater at all three times of measurement. The number and weight of green pods per plant 30 days after potassium naphthenate application were significantly larger, suggesting that the stimulative action of potassium naphthenate was in progress at the times of the assays. A mechanism, involving a genetic and a metabolic phase, is suggested for the stimulation of plant growth by naphthenate.
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PMID:Mechanism of plant growth stimulation by naphthenic Acid: effects on nitrogen metabolism of phaseolus vulgaris L. 1665 19

By altering key amino acid residues of the Alzheimer's disease-associated amyloid-beta peptide, we investigated the mechanism through which amyloid-beta inhibits cytochrome c oxidase (EC 1.9.3.1). Native amyloid-beta inhibited cytochrome oxidase by up to 65%, and the level of inhibition was determined by the period of amyloid-beta ageing before the cytochrome oxidase assay. Substituting tyrosine-10 with alanine did not affect maximal enzyme inhibition, but the altered peptide required a longer period of ageing. By contrast, oxidizing the sulfur of methionine-35 to a sulfoxide, or substituting methionine-35 with valine, completely abrogated the peptide's inhibitory potential towards cytochrome oxidase. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that the loss of inhibitory potential towards cytochrome oxidase with the methionine-35-altered peptides did not correlate with a substantially different distribution of amyloid-beta oligomeric species. Although the amyloid-beta-mediated inhibition of cytochrome oxidase was completely dependent on the presence of divalent Cu2+, it was not supported by monovalent Cu+, and experiments with catalase and H2O2 indicated that the mechanism of cytochrome oxidase inhibition does not involve amyloid-beta-mediated H2O2 production. We propose that amyloid-beta-mediated inhibition of cytochrome oxidase is dependent on the peptide's capacity to bind, then reduce Cu2+, and that it may involve the formation of a redox active amyloid-beta-methionine radical.
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PMID:Copper-dependent inhibition of cytochrome c oxidase by Abeta(1-42) requires reduced methionine at residue 35 of the Abeta peptide. 1698 48

There is evidence that nitric oxide (NO), superoxide (O(2)(*-)), and their associated reactive nitrogen species (RNS) produced by vascular endothelial cells (ECs) in response to hemodynamic forces play a role in cell signaling. NO is known to impair mitochondrial respiration. We sought to determine whether exposure of human umbilical vein ECs (HUVECs) to steady laminar shear stress and the resultant NO production modulate electron transport chain (ETC) enzymatic activities. The activities of respiratory complexes I, II/III, and IV were dependent on the presence of serum and growth factor supplement in the medium. EC exposure to steady laminar shear stress (10 dyn/cm(2)) resulted in a gradual inhibition of each of the complexes starting as early as 5 min from the flow onset and lasting up to 16 h. Ramp flow resulted in inhibition of the complexes similar to that of step flow. When ECs were sheared in the presence of the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME; 100 microM), the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO; 100 microM), or the peroxynitrite (ONOO(-)) scavenger uric acid (UA; 50 microM), the flow-inhibitory effect on mitochondrial complexes was attenuated. In particular, L-NAME and UA abolished the flow effect on complex IV. Increased tyrosine nitration was observed in the mitochondria of sheared ECs, and UA blocked the shear-induced nitrotyrosine staining. In summary, shear stress induces mitochondrial RNS formation that inhibits the electron flux of the ETC at multiple sites. This may be a critical mechanism by which shear stress modulates EC signaling and function.
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PMID:Shear-induced reactive nitrogen species inhibit mitochondrial respiratory complex activities in cultured vascular endothelial cells. 1702 Sep 31

In the brain, ischemic preconditioning (IPC) diminishes mitochondrial dysfunction after ischemia and confers neuroprotection. Activation of epsilon protein kinase C (epsilonPKC) has been proposed to be a key neuroprotective pathway during IPC. We tested the hypothesis that IPC increases the levels of epsilonPKC in synaptosomes from rat hippocampus, resulting in improved synaptic mitochondrial respiration. Preconditioning significantly increased the level of hippocampal synaptosomal epsilonPKC to 152% of sham-operated animals at 2 d of reperfusion, the time of peak neuroprotection. We tested the effect of epsilonPKC activation on hippocampal synaptic mitochondrial respiration 2 d after preconditioning. Treatment with the specific epsilonPKC activating peptide, tat-psiepsilonRACK (tat-psiepsilon-receptor for activated C kinase), increased the rate of oxygen consumption in the presence of substrates for complexes I, II, and IV to 157, 153, and 131% of control (tat peptide alone). In parallel, we found that epsilonPKC activation in synaptosomes from preconditioned animals resulted in altered levels of phosphorylated mitochondrial respiratory chain proteins: increased serine and tyrosine phosphorylation of 18 kDa subunit of complex I, decreased serine phosphorylation of FeS protein in complex III, increased threonine phosphorylation of COX IV (cytochrome oxidase IV), increased mitochondrial membrane potential, and decreased H2O2 production. In brief, ischemic preconditioning promoted significant increases in the level of synaptosomal epsilonPKC. Activation of epsilonPKC increased synaptosomal mitochondrial respiration and phosphorylation of mitochondrial respiratory chain proteins. We propose that, at 48 h of reperfusion after ischemic preconditioning, epsilonPKC is poised at synaptic mitochondria to respond to ischemia either by direct phosphorylation or activation of the epsilonPKC signaling pathway.
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PMID:Ischemic preconditioning targets the respiration of synaptic mitochondria via protein kinase C epsilon. 1841 96

Aerobic respiration of Streptococcus pyogenes and pneumococcus Type 1 are strongly inhibited by KCN, NaN(3), and Na(2)S. The anaerobic glycolysis of glucose by pneumococcus is also inhibited by KCN and NaN(3). Streptococcus pyogenes, E. coli, pneumococcus Type 1, B. subtilis, B. proteus, and Staphylococcus aureus did not catalyze the oxygen uptake by p-phenylenediamine in the presence of added cytochrome c or in its absence. Yeast cells, B. subtilis, and B. pyocyaneus oxidized p-phenylenediamine to a dark purple meriquinoid substance in contrast to the other bacteria mentioned above. Streptococcus pyogenes in contrast to pneumococcus Type 1 catalyzed the oxygen uptake by cysteine. Neither of these bacteria catalyzed the oxygen uptake by tyrosine, adrenaline, pyrocatechin, xanthine, and hypoxanthine. Streptococcus pyogenes, pneumococcus Type 1, and E. coli, boiled and not boiled, gave positive peroxidative tests with benzidine showing the presence of hematin compounds. The results discussed in the light of the interpretations offered by Keilin and Harpley show that Streptococcus pyogenes and pneumococcus Type 1 contain cyanide-sensitive respiratory systems which are different from the cytochrome c-cytochrome oxidase system.
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PMID:CYANIDE-SENSITIVE BACTERIAL RESPIRATORY SYSTEMS DIFFERENT FROM THE USUAL CYTOCHROME-CYTOCHROME OXIDASE SYSTEM. 1987 23


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