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)

The subunits of the cytochrome oxidase from bovine heart were isolated in large quantities suitable for amino acid sequence studies. The preparation of subunits III, IV, V, VI, and VII for sequence determination can be achieved without employing sodium dodecyl sulfate. The method presented essentially involves pyridine extraction, pH fractionation, ammonium sulfate fractionation, and various types of column chromatography. However, subunits I and II can be prepared only in the presence of sodium dodecyl sulfate by molecular sieve chromatography; subunit III can also be isolated in this manner. The separation of subunits is found to be hindered by phospholipids associated with the enzyme and therefore the phospholipid-depleted preparation is used as the starting material. The molecular weights of subunits I, II, III, IV, V, VI, and VII are 40,000, 21,000, 14,800, 13,500, 11,600, 9,500, and 7,600, respectively. These values are based on the results of the conventional Weber and Osborn method of gel electrophoresis in the presence of sodium dodecyl sulfate. The amino termini of subunits I and II have been determined as N-formylmethionine, and those of subunits III, IV, V, VI, and VII are alanine, alanine, serine, alanine, and an N-acetyl-blocked residue, respectively. The carboxyl termini for subunits I to VII are lysine, leucine, lysine, histidine, valine, isoleucine, and valine, respectively. The complete amino acid sequence of some subunits has been published and that of other subunits will be reported elsewhere in collaboration with the Amino Acid Sequence Group of Cytochrome Oxidase at the University of Hawaii.
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PMID:Large scale isolation and properties of subunits from bovine heart cytochrome oxidase. 627 Jan 41

Oxidized Pseudomonas cytochrome oxidase (ferrocytochrome c-551:oxidoreductase; EC 1.9.3.2), digested with subtilisin in the absence and presence of KCN, produces discrete, high molecular weight fragments. The presence of KCN alters the rate of this fragmentation but does not change the nature of the fragments. When digested in the absence of KCN, the oxidase gives a major product (A) which is enzymatically active and has an apparent Mr = 58,000 on sodium dodecyl sulfate polyacrylamide gel electrophoresis. In the presence of KCN, the major product (B) has Mr = 48,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis but with gel permeation high performance liquid chromatography it has an apparent Mr = 92,000. This implies that product B is dimeric, as is the parent enzyme which has Mr = 110,000 by high performance liquid chromatography. Absorption spectra of product B, isolated by gel filtration, show that it contains only the heme d1 moiety. The digestion time course indicates that the rate at which several minor products are formed is also dependent on the absence or presence of KCN. These observations suggest that the binding of KCN to the heme centers induces a conformational change in the enzyme so that the heme c-containing portion of the protein, which is at one end of the intact enzyme, can be removed without disrupting the integrity of the heme d1-containing portion.
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PMID:Controlled proteolysis by subtilisin as a probe for cyanide-induced conformational changes in Pseudomonas cytochrome oxidase. 627 87

The conditions for the preparation of the ferricytochrome a-ferrocytochrome a3-carbon monoxide complex (a3+, a3(2)+CO) of cytochrome oxidase [EC 1.9.3.1] by the ferricyanide-reoxidation method and some properties of the prepared complex were studied. The addition of a small volume of concentrated ferricyanide solution to the dithionite-reduced and carbon monoxide-treated cytochrome oxidase preparation was required to obtain the (a3+, a3(2)+CO) spectrum showing absorption maxima at 590, 545, and 429 nm. The addition of larger volumes of ferricyanide solution, thus introducing larger amounts of oxygen into the preparation, caused decomposition of the carbon monoxide complex. A part of the added ferricyanide was immediately reduced by dithionite whereas the remainder was gradually reduced by partial oxidation product(s) of dithionite. The (a3+, a3(2)+CO) complex was stable only when excess ferricyanide remained in the reaction mixture. The formation of the (a3+, a3(2)+CO) spectrum was observed when sodium citrate, phosphate or borate buffer containing either cholate or a non-ionic detergent was employed as the solvent buffer, but not with the buffers containing sodium dodecyl sulfate (SDS) or cetyltrimethyl-ammonium bromide (CETAB). The formation was considerably inhibited by trishydroxymethyl-aminomethane(Tris)-HCl buffer. The (a3+, a3(2)+CO) spectrum appeared with maximal intensity at around pH 7. The pH-dependency of the intensity of the spectrum was not in parallel with the pH-dependent change of the polymerization state of the cytochrome oxidase preparation. On freezing to liquid nitrogen temperature, the (a3+, a3(2)+CO) complex prepared in usual solvent buffers was mostly converted to the oxidized form of cytochrome oxidase (a3+, a3(3)+. However, when prepared in the phosphate buffer, pH 8.0, containing 1.2% (w/v) sodium cholate and with 20% saturation with ammonium sulfate, the complex mostly remained unchanged after the freezing. Based on the results obtained, the stability of the juxta-heme structure of cytochrome a3 was also discussed.
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PMID:Studies on the ferricytochrome a-ferrocytochrome a3-carbon monoxide complex of mammalian cytochrome oxidase. Conditions for preparation and some properties. 630 30

One of the first problems encountered by primitive cells was that of volume regulation; the continuous entry of ions, (eg, NaCl) and water in response to the internal colloid osmotic pressure threatening to destroy the cell by lysis. We propose that to meet this environmental challenge cells evolved an ATP-driven proton extrusion system plus a membrane carrier that would exchange external protons with internal Na+. With the appearance of the ability to generate proton gradients, additional mechanisms to harness this source of energy emerged. These would include proton-nutrient cotransport, K+ accumulation, nucleic acid entry, and motility. A more efficient system for the uptake of certain carbohydrates by vectorial phosphorylation via the PEP-phosphotransferase system probably appeared rather early in the evolution of anaerobic bacteria. The reversal of the proton-ATPase reaction to give net ATP synthesis became possible with the development of other types of efficient proton transporting machinery. Either light-driven bacterial rhodopsin or a redox system coupled to proton translocation would have served this function. Oxidation of one substrate coupled to the reduction of another substrate by membrane-bound enzymes evolved in such a manner that protons were extruded from the cell during the reaction. The progressive elaboration of this type of redox proton pump permitted the use of exogenous electron acceptors, such as fumarate, sulfate, and nitrate. The stepwise growth of these electron transport chains required the accretion of several flavoproteins, iron-sulfur proteins, quinones, and cytochromes. With modifications of these four basic components a chlorophyll-dependent photosynthetic system was subsequently evolved. The oxygen that was generated by this photosynthetic system from water would eventually accumulate in the atmosphere of the earth. With molecular oxygen present, the emergence of cytochrome oxidase would complete the respiratory chain. The proton economy of membrane energetics has been retained by most present-day microorganisms, mitochondria, chloroplasts, and cells of higher plants. A secondary use of the energy stored as an electrochemical difference of Na+ for powering membrane events probably also evolved in microorganisms. The exclusive age of the Na+ economy is distinctive of the plasma membrane of animal cells; the Na+-K+ ATPase sets up an electrochemical Na+ gradient that provides the energy for osmoregulation, Na+-nutrient co-transport, and the action potential of excitable cells.
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PMID:Evolution of membrane bioenergetics. 645 55

The single and combined influences of exercise training, chemical sympathectomy (SYMX), and surgical adrenal demedullation (D) were examined in four separate spontaneously hypertensive rat (SHR) groups. SYMX was accomplished by subcutaneous injections of antinerve growth factor (ANGF) over a 5-day period after birth followed by 20 separate injections of guanethidine sulfate during a 27-day period. Measurements of urine, plasma, or tissue levels of catecholamines indicated that these experimental procedures were effective. The animals were exercise trained (T) for 10 wk or longer at 40-60% of their VO2max capacity, and all T groups exhibited longer run times or higher muscle cytochrome oxidase activity; however, only the SHR + T subgroup had a significantly higher VO2max value than its control (NT). Training lowered resting systolic blood pressure (SBP) in the SHR subgroup but normalization of SBP occurred only with SYMX. Interestingly, only the SYMX + T subgroup with intact adrenal glands also had lower SBP values than the NT. The SHR + T and SYMX + T subgroups but not the SYMX + D + T had less cardiac acceleration after ip injections of atropine than their controls. Heavier heart weights were observed only in the SHR + T subgroup; SYMX was associated with lighter heart weights regardless of whether the rats had been T or D. These collective findings demonstrated again the importance of the sympathetic nervous system to an exercise response, suggesting that an intact adrenal medulla was essential for SHR groups to achieve many of the adaptations associated with training.
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PMID:Responses of SHR to combinations of chemical sympathectomy, adrenal demedullation, and training. 674 8

Two-dimensional crystals of beef heart mitochondrial cytochrome c oxidase dimers were labeled at Cys-115 of subunit III with a monomaleimide derivative of an undecagold cluster compound. The binding site of the gold cluster compound and hence the site of subunit III were identified by image processing of cryoelectron micrographs of the crystals preserved in a mixture of glucose and uranyl acetate. The shape of the cytochrome oxidase dimer can be approximated as a parallelogram which is 44 by 82 A with an included angle of 80 degrees oriented with its long dimension along the a axis of the crystal. Labeling of subunit III was confirmed by a shift in the mobility of approximately 50% of subunit III molecules upon electrophoresis in polyacrylamide gels in the presence of sodium dodecyl sulfate. Averaged images of undecagold cluster labeled crystals and of unlabeled crystals were calculated; each image represents an average of approximately 17,000 molecules of either labeled or unlabeled cytochrome oxidase. On the basis of a statistical analysis of the differences between the two images, the gold cluster binds along a line 30 degrees from the a axis and 29 A from the center of the dimer. This result is interpreted in the context of other structural studies including the site of cytochrome c binding which Frey and Murray found to be near the a axis and 18 A from the center of the dimer [Frey, T. G., & Murray, J. M. (1994) J. Mol. Biol. 237, 275-297].(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Electron microscopy of cytochrome c oxidase crystals: labeling of subunit III with a monomaleimide undecagold cluster compound. 794 82

The cytochrome oxidase/nitrite reductase of Pseudomonas aeruginosa has been purified to homogeneity as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. When this "homogeneous" protein is subjected to electrophoretic titration curve analysis in ampholines or to isoelectric focusing in immobilized pH gradient gels it is resolved into several bands, each of which possesses the olive-green color of the holoenzyme. Although the patterns of resolution replicate for a given enzyme preparation differences occur among different preparations. Furthermore, storage for several months at -20 degrees C leads to an increase in the number of isoelectrophoretic forms. All preparations, however, have two primary bands, one with a pI of 6.97 and the other of 7.02. Both these bands possess significant cytochrome oxidase activity after elution from the gels. When each of the primary bands is eluted and again subjected to isoelectric focusing under the same conditions as before, each band interconverts into two bands with pIs of 6.97 and 7.02. The addition of the ligand cyanide to the holoenzyme produces a shift in the pI of the two bands to pIs 7.04 and 7.12 while the addition of nitrite shifts some of the band at pI 6.97 into that at pI 7.02. The heme d1-containing dipeptide of the enzyme, produced by treatment with subtilisin, also exhibits considerable heterogeneity upon electrophoretic titration curve analysis and by isoelectric focusing in immobiline gels. Possible explanations for the observed isoelectrophoretic behavior in terms of protein conformation and heme chemistry are discussed.
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PMID:Isoelectrophoretic characterization of Pseudomonas cytochrome oxidase/nitrite reductase and its heme d1-containing domain. 838 8

Swayback disease, a neurodegenerative disorder of lambs, and Menkes disease, the human equivalent, are caused by a deficiency of dietary copper. Reports of low enzymic activity suggest that several copper-containing enzymes, including cytochrome-c oxidase (COX), may influence the progress of these diseases. To investigate its role in the development of neurodegenerative disorders, in particular swayback disease, we isolated COX from the brains and livers of swayback-diseased lambs. Comparative sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) combined with densitometric analysis revealed that whereas the structure of COX from the liver of diseased animals was normal, the corresponding brain enzyme was subunits II-, III-, and IV-deficient; the deficiency was 55, 30, and 65% respectively. The activities of liver and brain COX from normal and diseased lambs were compared by polarographic assay at low ionic strength. Whereas the enzyme from normal brains and both forms of the liver enzyme yielded characteristic biphasic Eadie-Hofstee plots, the brain enzyme from diseased animals displayed a single phase with a K(m) of 4.7 +/- 2.4 x 10(-6) M: the K(m) values of COX from the normal brain were 12 +/- 2.5 x 10(-6) and 5.5 +/- 0.5 x 10(-7) M. We conclude that the altered enzyme structure accounts for the uncharacteristic kinetics and low activity we have observed for the isolated brain enzyme. We also conclude that the altered enzyme structure partly accounts for the low oxidase activity and decreased ATP synthesis that has been widely reported for brain tissue from swayback-diseased animals. We postulate that the subunit deficiency probably results from incomplete crosslinking between the subunits and the membrane, and predict that similar structural and kinetic factors may also account for low COX activity in Menkes disease.
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PMID:Cytochrome-c oxidase isolated from the brain of swayback-diseased sheep displays unusual structure and uncharacteristic kinetics. 1032 20

Sequences in current databases show that a number of proteins involved in respiratory processes are homologous in archaeal and bacterial species. In particular, terminal oxidases belonging to oxygen, nitrate, sulfate, and sulfur respiratory pathways have been sequenced in members of both domains. They include cytochrome oxidase, nitrate reductase, adenylylsulfate reductase, sulfite reductase, and polysulfide reductase. These proteins can be assigned to the last common ancestor of living organisms assuming that the deepest split of the three domains of life occurred between Archaea and Bacteria and that they were not acquired through lateral gene transfer by one of these domains. These molecular data indicate that several of the most important respiratory pathways arose early in evolution and that the last common ancestor of living organisms was not a simple organism in its energetic metabolism. Rather, it may have been able to gain energy by means of at least four electron transport chains, and therefore it may have been prepared to face a wide range of environmental conditions.
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PMID:Respiratory chains in the last common ancestor of living organisms. 1048 3

Thiobacillus ferrooxidans cells grown on ferrous iron oxidized sulfite to sulfate at pH 3, possibly by a free radical mechanism involving iron and cytochrome oxidase. A purely chemical system with low concentrations of Fe3+ simulated the T. ferrooxidans system. Metal chelators, ethylenediamine tetraacetic acid (EDTA), 4,5-dihydroxy-1-3-benzene disulfonic acid (Tiron), o-phenanthroline, and 2,2'-dipyridyl, inhibited both sulfite oxidation systems, but the T. ferrooxidans system was inhibited only after the initial brief oxygen consumption. EDTA and Tiron, strong chelators of Fe3+, inhibited the oxidation at lower concentrations than o-phenanthroline and 2,2'-dipyridyl, strong chelators of Fe2+. Inhibition of Fe3+-catalyzed sulfite oxidation by EDTA and Tiron was instant, but the inhibition by o-phenanthroline and dipyridyl was briefly delayed, presumably for the reduction of Fe3+ to Fe2+. Mannitol, a free radical scavenger, inhibited both systems to the same extent. Cyanide and azide inhibited only the T. ferrooxidans system, suggesting a role of cytochrome oxidase. It is proposed that sulfite is oxidized by a free radical mechanism initiated by Fe3+ on the cell surface of T. ferrooxidans. Cytochrome oxidase is possibly involved in the regeneration of Fe3+ from Fe2+ by the normal Fe2+-oxidizing system of T. ferrooxidans.
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PMID:Sulfite oxidation by iron-grown cells of Thiobacillus ferrooxidans at pH 3 possibly involves free radicals, iron, and cytochrome oxidase. 1140 Jul 33


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