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)

The activity of cytochrome oxidase in tissues was decreased in short-term adaptation to reduce pO2 and administration of KCN in small doses. In the former case the activities of peroxidase and catalase were increased in blood. These effects as well as administration of Na2ATP into rats led to an increase in water content in tissues, to soption of acidic vital stain (phenol red) and to decrease in the ether-soluble fraction of lipids. The alterations were accompanied by decreased permeability of cells to n-hexane (estimation by gas-liquid chromatography). The decrease in cell permeability for nonelectrolytes was apparently due to conformational alterations in protein molecule of cytoplasmic membranes.
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PMID:[Hypoxia and tissue permeability for non-electrolytes]. 19 82

Changes in pH during the reactions of the fully reduced and mixed-valence cytochrome oxidase with molecular oxygen have been followed in flow-flash experiments, using the pH indicator phenol red. Solubilized enzyme as well as enzyme reconstituted into phospholipid vesicles has been studied. With the solubilized enzyme, a biphasic uptake of one proton from the medium was observed, whereas the reconstituted enzyme gave release of 1.3 protons to the extravesicular medium. It is concluded from these results that a total of two to three protons are taken up during oxidation of the fully reduced enzyme. Kinetic analysis suggests that the proton uptake is initiated by the transfer of the third electron to the oxygen binding site. A reaction scheme that integrates proton transfers and oxygen chemistry is presented.
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PMID:Uptake and release of protons during the reaction between cytochrome c oxidase and molecular oxygen: a flow-flash investigation. 184 96

The H+/e- stoichiometry for the proton pump of cytochrome c oxidase reportedly varies between 0 and 1, depending on experimental conditions. In this paper, we report the results obtained by a combination of transient optical spectroscopy with a time resolution of 10 ms and a singular value decomposition analysis to follow the kinetics, separate the observed spectral components, and quantitate the stoichiometry of the pump. By using cytochrome oxidase reconstituted into small unilamellar vesicles, we show that the time courses of ferrocytochrome c oxidation and phenol red acidification or alkalinization fit a simple kinetic scheme. The fitting procedure leads to unbiased and objective determination of the H+/e- ratio under various experimental conditions. The proton-pumping stoichiometry was found to be 1.01 +/- 0.10, independent of the number of turnovers, proton back-leak rate, or type of experiment (oxidant or reductant pulse).
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PMID:Proton pumping by cytochrome oxidase as studied by time-resolved stopped-flow spectrophotometry. 839 82

The degradation of the toxic phenol p-cresol by Pseudomonas bacteria occurs by way of the protocatechuate metabolic pathway. The first enzyme in this pathway, p-cresol methylhydroxylase (PCMH), is a flavocytochrome c. The enzyme first catalyzes the oxidation of p-cresol to p-hydroxybenzyl alcohol, utilizing one atom of oxygen derived from water, and yielding one molecule of reduced FAD. The reducing electron equivalents are then passed one at a time from the flavin cofactor to the heme cofactor by intramolecular electron transfer, and subsequently to cytochrome oxidase within the periplasmic membrane via one or more soluble electron carrier proteins. The product, p-hydroxybenzyl alcohol, can also be oxidized by PCMH to yield p-hydroxybenzaldehyde. The fully refined X-ray crystal structure of PCMH in the native state has been obtained at 2. 5 A resolution on the basis of the gene sequence. The structure of the enzyme-substrate complex has also been refined, at 2.75 A resolution, and reveals significant conformational changes in the active site upon substrate binding. The active site for substrate oxidation is deeply buried in the interior of the PCMH molecule. A route for substrate access to the site has been identified and is shown to be governed by a swinging-gate mechanism. Two possible proton transfer pathways, that may assist in activating the substrate for nucleophilic attack and in removal of protons generated during the reaction, have been revealed. Hydrogen bonding interactions between the flavoprotein and cytochrome subunits that stabilize the intramolecular complex and may contribute to the electron transfer process have been identified.
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PMID:Structures of the flavocytochrome p-cresol methylhydroxylase and its enzyme-substrate complex: gated substrate entry and proton relays support the proposed catalytic mechanism. 1062 31

Mitochondrial DNA (mtDNA) sequences from eight species of myiasis-causing flies, stored for up to 50 years, were amplified successfully. Universal primers were used to amplify six specific regions from total genomic DNA, including five mtDNA genes. The comparison of phenol/chloroform, DNAzol and Chelex techniques for DNA extraction showed that the DNAzol reagent was the most efficient in retrieving DNA from museum specimens, although the Chelex extraction procedure is currently the most frequently reported method. Comparison of the universal primer sequences with the homologous sequences of Cochliomyia hominivorax Coquerel and Chrysomya putoria Wiedemann (Diptera: Calliphoridae) revealed mismatches that could contribute to the low recovery of a short sequence from subunit II of cytochrome oxidase. The ability to characterize mtDNA markers from museum specimens should be useful in comparative studies of contemporary samples and should help in elucidating species introduction, colonization and dispersal.
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PMID:Methods for the recovery of mitochondrial DNA sequences from museum specimens of myiasis-causing flies. 1196 80

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

Aging alters a variety of physiological functions of the heart. The molecular basis of the age-related functional changes has not been fully understood. Differential gene expression provides the basis for many fundamental cellular processes associated with development and aging. The identification and cloning of genes whose expression is modulated by aging can be of importance for our better understanding of these age-related phenomena. In order to isolate and characterize gene products differentially expressed in senescent hearts, we applied a differential display method for screening those genes in rat ventricular myocardium. Total RNAs were isolated from 2-month-old (young) and 24-month-old rat (senescent) ventricles by the acid-guanidium-phenol-chloroform method. The first-strand synthesis of the cDNAs from each RNA was carried out with oligo-d(T) primers. The differential display screening was performed with three arbitrary primers and eight anchor primers, and the products were isolated on a 6% denaturing polyacrylamide gel. The bands showing differential expression were excised and subcloned into T-vector. We selected 19 upregulated clones and 66 downregulated clones in aged rat hearts. The differential expression of those candidate genes was confirmed by reverse Northern blot analysis. The selected genes were sequenced by dye-terminator methods. Among 31 clones, 15 clones were unknown. The known products included alpha-myosin heavy chain, cytochrome oxidase subunit, H(+)-transporting ATP synthase F0 complex subunit c isoform 3 (ATP5G3), and Na(+)-K(+)-Cl(-) cotransporter. The RT-PCR differential display method effectively identified genes differentially expressed in senescent hearts, and may be a useful tool for investigating factors responsible for age-related physiological changes.
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PMID:Investigation of differentially expressed genes in the ventricular myocardium of senescent rats. 1680 79

Phialocephala fortinii s.1. and Acephala applanata are the dominant dark septate endophytes (DSE) in roots of many trees and shrubs. Population genetic analysis led to the discovery of morphologically indistinguishable but reproductively isolated cryptic species (CSP) within Phialocephala fortinii s.1. In the present study we show that sequence data of two coding (beta-tubulin and translation elongation factor [EF-lalpha]) and three noncoding DNA loci confirm subdivision of P. fortinii s.1. and allow to differentiate seven CSP of P. fortinii. In addition we show that strains collected throughout Europe can be classified correctly based on these sequence markers. Statistically significant differences in growth response on different media were observed among CSP of P. fortinii and A. applanata. Growth inhibition on MEA amended with 100 mgl(-1) cycloheximide had the strongest differential effect of all physiological traits examined. In contrast exoenzyme production (laccase, proteinase, pectinase, phenol-oxidase, amylase, cytochrome oxidase and tyrosinase) rarely helped to differentiate CSP of P. fortinii. However A. applanata was a strong producer of amylases, laccases and proteinases. Based on these data we propose to assign species rank to six CSP of P. fortinii: P. turiciensis, P. letzii, P. europaea, P. helvetica, P. uotolensis, P. subalpina spp. nov. and P. fortinii s.s.
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PMID:Assignment of species rank to six reproductively isolated cryptic species of the Phialocephala fortinii s.1.-Acephala applanata species complex. 1848 52

Natural Phytophthora hybrids (P. nicotianae x P. cactorum) infecting loquat in Peru and Taiwan were characterized with AFLP (amplified fragment length polymorphism) markers, the internal transcribed spacer (ITS) region and the phenol acid carboxylase gene (Pheca) and inheritance of the mitochondrial cytochrome oxidase I gene (coxI). AFLP profiles of two Taiwanese isolates recovered in 1995 were polymorphic in approximately 50% of the fragments whereas five Peruvian isolates, recovered 2002-2003 and 2007, showed no genotypic variation. Sequencing analysis of the cloned ITS region resulted in the identification of sequences with high homology to either P. nicotianae (99%) or P. cactorum (97%). Direct sequence analysis of the Pheca gene revealed 13 heterozygous sites suggesting the presence of both P. nicotianae and P. cactorum genes in P. hybrids isolates. Melting analyses of coxI suggested that all seven Phytophthora hybrids inherited the mitochondrial DNA from P. nicotianae. Our results suggest that Phytophthora hybrids from Peru might have originated from a single hybridization event and that the two isolates from Taiwan might have originated through different hybridization events. The Peruvian hybrids appear to have persisted at least 3 y at three locations. Possible factors influencing the population structure of Phytophthora hybrids infecting loquat are discussed.
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PMID:Molecular comparison of natural hybrids of Phytophthora nicotianae and P. cactorum infecting loquat trees in Peru and Taiwan. 1962 29

Several lines of evidence suggest that many cases of Alzheimer's disease (AD) may be due to genetic factors. We used subtraction hybridization to isolate genes that were differentially expressed in AD compared to control brains. Directionally cloned cDNA libraries from AD and control patients' cerebral temporal cortices were used for the production of sense and antisense cDNA using the polymerase chain reaction (PCR). A 30- to 40-fold excess of sense cDNA from Alzheimer's disease brain was photobiotinylated and hybridized to (32)P-labeled antisense cDNA from control brain. The hybridized and unhybridized "driver" DNA was removed by streptavidin binding and phenol extraction. The subtracted antisense cDNA sequences were PCR amplified and cloned into lambda-GEM-4 producing a subtracted cDNA library. This subtracted cDNA library was rescreened using duplicate differential colony hybridization to select specific subtracted clones. An 850-bp cDNA that was overexpressed in the AD compared to the control library was isolated and sequenced. It had >95% homology to cytochrome oxidase subunit 3. Overexpression of this gene in AD brains was confirmed using Northern blots. Since cytochrome oxidase is important for neuronal function, these findings suggest a possible role for this gene in the pathogenesis of AD.
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PMID:Isolation of a cytochrome oxidase gene overexpressed in Alzheimer's disease brain. 1991 89


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