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

---

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

The mitochondria isolated from the ciliate protozoon Tetrahymena pyriformis carry an oxidative phosphorylation with P/O ratio of 2 for succinate oxidation and P/O ratio of 3 for the oxidation of the NAD-linked substrates. The respiration is more than 90% inhibited with 1 mM cyanide while antimycin A and rotenone inhibit at concentrations of 1000-fold higher than those effective in mammalian mitochondria. Using a combination of spectral studies and potentiometric titrations, the components of the respiratory chain were identified and characterized with respect to the values of their half-reduction potentials. In the cytochrome bc1 region of the chain a cytochrome c was present with an Em7.2 of 0.225 V and two components with absorption maxima at 560 nm and the half-reduction potential values of -0.065 and -0.15 V at pH 7.2. The cytochrome with the more positive half-reduction potential was identified as the analogue of the cytochrome(s) b present in mitochondria of higher organisms, while the cytochrome with the more negative half-reduction potential was tentatively identified as cytochrome o. In addition ubiquinone was present at a concentration of approx. 4 nmol per mg mitochondrial protein. In the spectral region where cytochromes a absorb at least three cytochromes were found. A cytochrome with an absorption maximum at 593 nm and a midpoint potential of -0.085 V at pH 7.2 was identified as cytochrome a1. The absorption change at 615-640 nm, attributed usually to cytochrome a2, was resolved into two components with Em7,2 values of 0,245 and 0.345 V. It is concluded that the terminal oxidase in Tetrahymena pyriformis mitochondria is cytochrome a2 which in its two component structure resembles cytochrome aa3.
...
PMID:Mitochondrial respiratory chain of Tetrahymena pyriformis. The thermodynamic and spectral properties. 40 46

A rate of endogenous respiration in mitochondria of rabbit brain visual system (visual cortex, forebrain) was higher under conditions of light deprivation (from birth up to 2.5 month) as compared with the mitochondria of control animals. The mitochondria of experimental rabbits were characterized by distinct alteration in oxidative phosphorylation of glutamic acid, by an increased rate of electron transport at the step between cytochrome c-cytochrome oxidase-succinate dehydrogenase of the respiratory chain as well as by the peculiar effect of rothenone and DNP on the chain. All the patterns studied approached the control value within the period of restoration of light impulsation. Nonlinear type of the regenerating processes was observed. Role of specific impulsation and compensatory reactions in the age-dependent development of energy processes in brain mitochondria is discussed.
...
PMID:[Mitochondrial energy processes of the visual system in the rabbit brain normally and under conditions of light deprivation]. 49 32

Redox reactions were studied in 217 placentas obtained after partus maturus and pathological labor (premature labor, gestoses, incompatibility by Rh antigen, uterine inertia, placentas at early therapeutic and spontaneous abortions). Several uniform alterations were observed in activities of NADP-dependent isocitrate dehydrogenase, lactate-, glutamate- and malate dehydrogenases. Increase in the activity of these enzymes was accompanied by alteration in distribution of LDH isoenzymes and by elevated formation of glutamic acid; activities of transaminases, cytochrome c and cytochrome oxidase were unaltered. The alterations observed appear to be due to activation of compensatory-adaptive mechanisms of placenta.
...
PMID:[Role of oxidative processes in the realization of the adaptive mechanisms of the human placenta]. 59 4

The present work is a continuation of our studies on mitochondrial functions and enzyme activities after acute exhaustive swimming in liver and myocardium. In rat heart mitochondria the activities of SDH, cytochrome oxidase and ATPase (DNP-stimulated) increase after swimming and remain at that level until the end of the 22-hour rest period studied. The enzyme complexes--rotenone-sensitive NAD. H-cytochrome c-reductase and succinate-cytochrome c-reductase--decrease their activities in both experimental groups. The reduced activity of these two enzymes is determined by changes in this part of the respiratory chain which occur after the incorporation of DCPIP in the oxidation-reduction processes. The marker enzyme of the outer mitochondrial membranes--rotenone-insensitive NAD.H-cytochrome c-reductase--reveals unchanged activity after swimming and a 22-hour period of rest. The different changes in the activities of enzymes with different localization and organization in heart mitochondria are explained by disorganization of the inner membranes after exhaustive swimming, which could induce both activation of some enzymes and inhibition of others. The effect of certain factors during muscle exercise which could cause the established structural and functional changes in the mitochondria is discussed.
...
PMID:Effect of single exhaustive swimming on mitochondrial enzyme activities in rat myocardium. 61 30

1. Carbon monoxide (CO) acts competitively towards oxygen when the latter is taken up in respiration by cytochrome aa3-containing proteoliposomes, both in the presence of p-trifluoromethoxy carbonyl cyanide phenylhydrazone and valinomycin (deenergized state) and in their absence (energized state). At high levels of CO, the double reciprocal plots (1/v vs. 1/[O2]) in the energized and deenergized states are parallel, i.e. energization acts "anti-competitively" towards oxygen, and the "respiratory control ratio" decreases as the oxygen concentration decreases. 2. Azide acts non-competitively towards cytochrome c when the latter is oxidized by cytochrome aa3-containing proteoliposomes both in the energized and deenergized (plus p-trifluoromethoxy carbonyl cyanide phenylhydrazone and valinomycin) conditions. At low azide concentrations the apparent Ki for azide is unaffected by energization, but at high azide levels the Ki increases in energized liposomes, i.e. the "respiratory control ratio" decreases as the azide concentration increases. 3. It is concluded that the inhibitor experiments are consistent with but do not prove the concept that the oxidase molecules in a single vesicle are responding to a single "energization state" or set of electrochemical gradients. This and other models are discussed.
...
PMID:Control of respiration in proteoliposomes containing cytochrome aa3. II. Inhibition by carbon monoxide and azide. 65 7

The low-spin ferric cyanide complex of beef heart cytochrome aa3 can be partially reduced by stoichiometric additions of ferrous cytochrome c or by similar additions of N,N,N',N'-tetramethyl-p-phenylene diamine. In both cases the initial ratio of cytochrome c oxidized: cytochrome a reduced or Wurster's Blue: cytochrome a reduced approximates the value 2. It is concluded that the binding of a single HCN prevents the reduction of both cytochrome a3 and its associated EPR-invisible Cu atom.
...
PMID:Redox state of the partially reduced cytochrome aa3- cyanide complex. 71 82

In liver mitochondria of control animals and of animals subjected to swimming for three hours experiments are made to determine the activities of rotenone-insensitive NAD.H-cytochrome c-oxireductase, succinate-cytochrome c-oxireductase, MDH, SDH, ATP-ase and cytochrome oxidase, as well as oxygen uptake, respiratory control index and ADP/O ratio upon oxidation of succinate and glutamate + malate. Decrease of the ADP/O ratio and of the respiratory control index, as well as increased ATP-ase activity, are established after swimming. The e--transport rate decreases. The activity of the remaining enzymes is unchanged. The activities of MDH, SDH, NAD.H-cytochrome c- and succinate-cytochrome c-oxireductases decrease 22 hours after exhaustive swimming. The activities of the cytochrome oxidase and the ATP-ase are unchanged compared with the controls. A single exhaustive loading results in changes in the capacity of phosphorylation in the liver mitochondria and the changes in the activities of the enzymes studied are established 22 hours later.
...
PMID:Effect of exhaustive swimming on the oxidative phosphorylation and the activity of some enzymes in rat liver mitochondria. 101 5

Pseudomonas AM1, Hyphomicrobium X and Pseudomonas MS all contain cytochrome a/a(3) and a b-type cytochrome able to react with CO. Pseudomonas AM1 and Hyphomicrobium X also have a CO-binding cytochrome c. The purified cytochrome c (redox potential 0.26V) of Pseudomonas AM1 was not susceptible to oxidation by molecular oxygen. CO reacted slowly with the reduced form giving a CO difference spectrum with a peak at 412nm and troughs at 420nm and 550nm. Similar results were obtained with the cytochrome c of Hyphomicrobium (aerobically grown or anaerobically grown with nitrate) and with that of Pseudomonas extorquens. The results given in the present paper are incompatible with an oxygenase or oxidase function for the soluble cytochrome c of methylotrophs. Studies with whole cells of Pseudomonas AM1 and a cytochrome c-deficient mutant have demonstrated that cytochrome b (redox potential 0.009V) is the first cytochrome in the electron-transport chain for oxidation of all substrates except methanol (and ethanol) whose oxidation does not involve this cytochrome. All substrates are usually oxidized by way of cytochrome c and cytochrome oxidase (cytochrome a/a(3)), but there is an alternative route for the reduction of cytochrome a/a(3) in the mutant lacking cytochrome c. Results of experiments on cyanide inhibition of respiration and cytochrome oxidation support the suggestion that the susceptibility of cytochrome b to oxidation by molecular oxygen (reflected in its ability to react with CO) is probably irrelevant to the normal physiology of Pseudomonas AM1.
...
PMID:The microbial metabolism of C1 compounds. The electron-transport chain of Pseudomonas am1. 122 Jun 89

Mouse myeloma cells and mitochondria had the same kinds of cytochrome components in the respiratory chain as the normal ones. Their constitution, however, was abnormally different from that found in normal cells and mitochondria. The cytochrome aa3 concentration was especially low in the myeloma as compared with cytochrome c concentration, and the resulting cytochrome aa3/c ratio was 0.25, which was the lowest ever reported in animal mitochondria. Normal lymph node cells, producing the immunoglobulin similar to the myeloma cells, had a ratio of 1.1. Human myeloma mitochondria had the same characteristics as the mouse myeloma. Ascite form myeloma originated from mouse solid from myeloma grew faster, and yet aa3/c of 0.5 in the ascites myeloma was found to be quite similar to that observed in various ascites tumor cells such as hepatomas, Ehrlich and sarcoma 180. A significant part of the cytochromes in the respiratory chain of the mouse myeloma remained in the oxidized form in the cyanide-inhibited or anaerobic states, and was reduced only by the addition of dithionite. The properties of the b cytochromes in mouse myeloma mitochondria are also described and discussed in the context of multiple forms of the b cytochromes in the respiratory chain.
...
PMID:An abnormal ratio of cytochromes in the respiratory chain of mouse and human myelomas. 125 59

The cytochrome o complex of Escherichia coli is a ubiquinol oxidase which is the predominant respiratory terminal oxidase when the bacteria are grown under high oxygen tension. The amino acid sequences of three of the subunits of this quinol oxidase reveal a substantial relationship to the aa3-type cytochrome c oxidases. The two cytochrome components (b563.5 and o) and the single copper (CuB) present in the E. coli quinol oxidase appear to be equivalent to cytochrome a, cytochrome a3, and CuB of the aa3-type cytochrome c oxidases, respectively. These three prosthetic groups are all located within subunit I of the oxidase. Sequence alignments indicate only six totally conserved histidine residues among all known sequences of subunit I of the cytochrome c oxidases of various species plus the E. coli quinol oxidase. Site-directed mutagenesis has been used to change each of these totally conserved histidines with the presumption that two of these six must ligate to the low spin cytochrome center of the E. coli oxidase. The presence of the low spin cytochrome b563.5 component of the oxidase can be evaluated both by visible absorbance properties and by its EPR spectrum. The results unambiguously indicate that His-106 and His-421 are the ligands of the six-coordinate low spin cytochrome b563.5. Although the data are not definitive in making additional metal ligation assignments of the remaining four totally conserved histidines, a reasonable model is suggested for the structure of the catalytic core of the cytochrome o complex and, by extrapolation, of cytochrome c oxidase.
...
PMID:Determination of the ligands of the low spin heme of the cytochrome o ubiquinol oxidase complex using site-directed mutagenesis. 130 9


<< Previous 1 2 3 4 5 6 7 8 9 10

---