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 content of cytochromes a,b and c, the activity of marker enzymes of the matrix and inner membrane of the mitochondria: glutamate dehydrogenase and cytochrome oxidase, as well as the rate of absorption of O2 by root segments in the presence of respiratory substrates, oxygen, inhibitors of respiration, and dinitrophenol, were determined. The intensification of cell respiration in the phase of elongation is determined not so much by new formation of cytochrome components of the respiratory cycle (during this period there is an accumulation only of cytochrome c) as by reorganization of the respiratory cycle (primarily its portion NADH - cytochrome b) and synthesis of enzymes of the matrix.
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PMID:Formation of the enzymatic apparatus of respiration in growing cells. Communication II. Reorganization of the respiratory cycle of mitochondria in the corn root tip. 16 96

The synthesis of cytochromes aa3, b, and c has been investigated during synchronous growth in the yeast, Saccharomyces cerevisiae. These cytochromes increase in concentration continuously throughout each cell cycle, with an approximate doubling in rate during successive cycles. The rates of cytochrome formation are considerably higher in galactose-grown cultures than in cells grown in glucose. Although cytochrome aa3 increases at a continuous rate, its functional counterpart, cytochrome c oxidase, increases in stepwise fashion, with the increments occurring at the beginning of each new cell cycle. Chloramphenicol, a specific inhibitor of intramitochondrial protein synthesis, inhibits the formation of cytochrome aa3 at all stages of the cell cycle, but does not inhibit cytochrome c. Chloramphenicol exhibits a somewhat intermediate effect on cytochrome b synthesis, with transient inhibition occurring only when the drug is added prior to or during the initial part of the first cell cycle. After this time, chloramphenicol had no effect on the rate of cytochrome b synthesis. The data indicate that under our conditions of cell synchrony mitochondrial membrane formation as reflected by increments in mitochondrial cytochromes occurs by continuous accretion of new material throughout the cell cycle. Intramitochondrially synthesized polypeptide products, responsible for the formation of new cytochrome aa3, appear to be synthesized throughout the cell cycle.
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PMID:Cytochrome synthesis in synchronous cultures of the yeast, Saccharomyces cerevisiae. 16 91

The effect of antimycin on (i) the respiratory activity of the KCN-insensitive pathway of mitochondria of Neurospora grown on chloramphenicol (chloramphenicol-grown) with durohydroquinone and succinate or NADH as substrate, (ii) the electron transfer from the b-type cytochromes to ubiquinone with durohydroquinone as electron donor as well as (iii) the electron transfer from the b-type cytochromes to duroquinone with succinate as electron donor in chloramphenicol-grown Neurospora and beef heart submitochondrial particles was studied. All experiments were performed in the uncoupled state. 1. The respiratory chain of chloramphenicol-grown Neurospora mitochondria branches at ubiquinone into two pathways. Besides the cytochrome oxidase-dependent pathway, a KCN-insensitive branch equiped with a salicylhydroxamate-sensitive oxidase exists. Durohydroquinone, succinate or NADH are oxidized via both pathways. The durohydroquinone oxidation via the KCN-insensitive pathway is inhibited by antimycin, wheras the succinate or NADH oxidation is not. The titer for ful inhibition is one mol antimycin per mol cytochrome b-563 or cytochrome b-557. 2. The electron transfer from durohydroquinone to ubiquinone, which takes place in the KCN-inhibited state, does not occur in the antimycin-inhibited state. 3. The reduction of duroquinone by succinate in the presence of KCN is inhibited by antimycin. The titer for full inhibition is one mol antimycin per mol cytochrome b-566 or cytochrome b-562 for beef heart (or cytochrome b-563 or cytochrome b-557 for Neurospora). 4. When electron transfer from the b-type cytochromes to cytochrome C1, ubiquinone and duroquinone is inhibited by antimycin, the hemes of cytochrome b-566 and cytochrome b-562 (or cytochrome b-563 and cytochrome b-557) are in the reduced state. 5. The experimental results suggest that the two b-type cytochromes form a binary complex the electron transferring activity of which is inhibited by antimycin, the titer for full inhibition being one mol of antimycin per mol of complex. The electron transfer from the b-type cytochromes to ubiquinone is inhibited in a non-linear fashion.
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PMID:Inhibition of electron transfer from ferrocytochrome b to ubiquinone, cytochrome c1 and duroquinone by antimycin. 16 67

1. In mitochondrial particles antimycin binds to two separate specific sites with dissociation constants KD1 less than 4 - 10(-13) M and KD2 = 3 - 10(-9) M, respectively. 2. The concentrations of the two antimycin binding sites are about equal. The absolute concentration for each binding site is about 100 - 150 pmol per mg of mitochondrial protein. 3. Antimycin bound to the stronger site mainly inhibits NADH-and succinate oxidase. Binding of antimycin to the weaker binding site inhibits the electron flux to exogenously added cytochrome c after blocking cytochrome oxidase by KCN. 4. Under certain conditions cytochrome b and c1 are dispensible components for antimycin-sensitive electron transport. 5. A model of the respiratory chain in yeast is proposed which accounts for the results reported here and previously. (Lang, B., Burger, G., and Bandlow, W. (1974) Biochim. Biophys. Acta 368, 71-85).
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PMID:Studies on the mechanism of electron transport in the bc1-segment of the respiratory chain in yeast. II. The binding of antimycin to mitochondrial particles and the function of two different binding sites. 16 19

The midgut of Hyalophora cecropia actively transports potassium from hemolymph to lumen and the energy for this process appears to be intimately linked to oxidative metabolism. In the present investigation, we monitored concurrently the rate of active transport and the redox levels of the components of the respiratory chain in the intact tissue under a variety of experimental conditions. Approximately equal concentrations of cytochromes a3, a, c and b-557 were found. Other investigators (Pappenheimer, Jr, A.M. and Williams, C.M. (1954) J. Biol. Chem. 209, 915, Shappirio, D.G. and Williams, C.M. (1957) Proc. R. Soc. Lond. Ser. B 147, 233 and Chance, B. and Pappenheimer, Jr, A.M. (1957) J. Biol, Chem, 209, 931) have indentified cytochrome b-557 with b5 and found that it exists primarily in an extramitochondrial location. Steady-state experiments demonstrated that all these cytochromes were approximately 50% reduced while active transport proceeded at a high rate in regular cecropia Ringer containing 32 mM KCl. When the potassium concentration was reduced, the active transport decreased and all the cytochromes became more oxidized. Addition of 1 mM cyanide inhibited active transport by 90% and caused a 100% reduction of all cytochromes. Redox state and short circuit current (Isc) kinetics measured as the tissue was made anoxic showed that all the respiratory enzymes, except cytochrome b-557, became fully reduced at a faster rate than the rate of inhibition of the Isc. The rate of cytochrome b-557 reduction followed kinetically the Isc. These observations are interpreted in a scheme where cytochrome b-557 (possibly b5) branches off cytochrome c from the conventional resporatory chain, utilizing cytochrome a3 as the terminal oxidase for both branches. Cytochrome b-557 may be involved in providing a direct link between oxidative metabolism and active transport in the midgut of the silkworm.
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PMID:Redox state of respiratory chain enzymes and potassium transport in silkworm mid-gut. 17 28

1. Three methods are described for the genetic analysis of yeast cytoplasmic mutants (mit- mutants) lacking cytochrome oxidase or coenzyme QH2-cytochrome c reductase. The procedures permit mutations in mitochondrial DNA to be mapped relative to each other and with respect to drug-resistant markers. The first method is based upon the finding that crosses of mit- mutants with some but not other isonuclear q- mutants lead to the restoration of respiratory functions. Thus a segment of mitochondrial DNA corresponding to a given mit- mutation or to a set of mutations can be delineated. The second method is based on the appearance of wild-type progeny in mit- X mit- crosses. The third one is based on the analysis of various recombinant classes issued from crosses between mit-, drug-sensitive and mit+, drug-resistant mutants. Representative genetic markers of the RIBI, OLII, OLI2 and PAR1 loci were used for this purpose. 2. The three methods when applied to the study of 48 mit- mutants gave coherent results. At least three distinct regions on mitochondrial DNA in which mutations cause loss of functional cytochrome oxidase have been established. A fourth region represented by closely clustered mutants lacking coenzyme QH2-cytochrome c reductase and spectrally detectable cytochrome b has also been studied. 3. The three genetic regions of cytochrome oxidase and the cytochrome b region were localized by the third method on the circular map, in spans of mitochondrial DNA defined by the drug-resistant markers. The results obtained by this method were confirmed by analysis of the crosses between selected mit- mutants and a large number of q- clones whose retained segments of mitochondrial DNA contained various combinations of drug-resistant markers. 4. All the genetic data indicate that the various regions studied are dispersed on the mitochondrial genome and in some instances regions or clusters of closely linked mutations involved in the same respiratory function (cytochrome oxidase) are separated by other regions which code for entirely different functions such as ribosomal RNA.
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PMID:Localization in yeast mitochondrial DNA of mutations expressed in a deficiency of cytochrome oxidase and/or coenzyme QH2-cytochrome c reductase. 17 53

Rat heart and liver cytochrome concentrations were determined after three hypoxic conditions (atmospheric pressure 50.5 kPa, 40.8 kPa and 38.0 kPa) lasting one week and two weeks. The heart showed clear hypertrophy which was 38% in most severe hypoxia (38 kPa, 2 weeks). A small decline in the liver weight to body weight ratio was observed, this decrease being 21% in the most severe case. During the hypoxic periods the mitochondrial cytochrome concentration decreased. This phenomenon was more obvious when the degree of hypoxia was increased and more pronounced after 2 weeks than one week. The heart and liver showed quite similar patterns in this respect. In most severe hypoxia the decreases in the liver were 29% for cytochrome aa3, 30% for cytochrome b, 20% for cytochrome c and 15% for cytochrome c1, with the concentrations expressed on mitochondrial protein basis. The corresponding values in the heart were 31%, 43%, 28%, and 22%. It can be concluded that in mammals the mitochondrial cytochrome content probably varies according to the amount of oxygen available.
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PMID:Mitochondrial cytochrome concentrations in rat heart and liver as a consequence of different hypoxic periods. 17 79

A cytochrome b complex and cytochrome oxidase have been purified 14- and 20-fold respectively from yeast submitochondrial particles by a simple procedure involving their spontaneous precipitation from a deoxycholate extract. The recovery of both proteins was almost quantitative. The specific heme contents were 11 and 8 nmoles/mg protein for the cytochrome b complex and cytochrome oxidase respectively and both were spectrally pure. Sodium dodecyl sulfate gel electrophoresis resolved the cytochrome b complex into seven distinct subunits with molecular weights 42,000, 33,000, 27,500, 23,000, 15,500, 13,000 and 10,500. Cytochrome oxidase contained five bands with molecular weights 42,000, 26,500, 21,000, 14,000 and 10,500.
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PMID:Isolation and partial charcterization of a cytochrome b complex and cytochrome oxidase from yeast mitochondria. 18 46

Tridemorph (N-tridecyl-2,6-dimethylmorpholine) inhibits both the NADH-oxidase and the succinate-cytochrome c oxydoreductase system of non-phosphorylating electron transfer particles from beef heart. The concentration required for half-inhibition amounted to 3,4 muM and 24 muM respectively. Two different sites of action in the respiratory chain could be localized by means of difference spectroscopy and measurements of enzymic activities in various partial systems. The inhibition of the NADH-ubiquinone oxydoreductase activity as well as the suppression of the NADH-induced reduction of all cytochromes on the one hand and the insensitivity of the NADH-ferricyanide oxydoreductase system on the other argue in favour of a site of action similar to rotenone. The partial suppression of the succinate-induced reduction of cytochrome b with simultaneous complete inhibition of the reduction of the other cytochromes indicate an additional site of action analogous to antimycin A. Both inhibitory actions appeared instantaneously after the addition of tridemorph and were counteracted by serum albumin. Furthermore, tridemorph inhibited the oxydation of external ferrocytochrome c but not that of ascorbate/tetra-methyl-p-phenylene-diamine-HCI (TMPID) showing that it is not a true inhibitor of the cytochrome oxidase. The TMPD-induced bypass of the succinate oxidation was inhibited as well. The possible role of the inhibition of the main pathway of the respiratory chain for the fungicidal action of tridemorph is discussed.
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PMID:[The systemic fungicide tridermorph as an inhibitor of the respiratory chain of electron transfer particles from beef heart mitochondria]. 18 65

Nineteen mutants of S. cerevisiae exhibiting a double deficiency in cytochrome oxidase and coenzyme QH2-cytochrome c reductase (also cytochrome b deficient) have been studied. The mutants have been crossed to a set of rho- tester strains with different segments of mitochondrial DNA. The mutants have also been crossed to mit- testers with defined genetic lesions. In addition, crosses were performed with a respiratory competent strain to ascertain whether mitotic and meiotic segregants could be isolated with only one of the two enzymatic deficiencies. The rho- testers allowed the doubly deficient mutants to be separated into two classes. Mutants in class 1 were not restored by any of the rho- testers and appeared to have separate mutations, one in cytochrome oxidase and the other in cytochrome b. Mutants in class 2 were restored by a set of rho- clones whose retained segments of mitochondrial DNA contained the cytochrome b but not the cytochrome oxidase loci. These appeared to behave as single hit mutations. Further studies, however, indicated that both class 1 and class 2 mutants carried separate mutations in two different loci. Mitotic and meiotic segregants with a single enzymatic deficiency could be isolated. In a number of strains, the mutations were mapped in known cytochrome oxidase and cytochrome b loci. The apparent discrepancy of the rho- tests for the class 2 mutants was shown to be probably due to a high unstability in one of the mutations. It has been concluded that all the doubly deficient strains carry two mutations in previously described cytochrome oxidase and cytochrome b loci. This conclusion argues against the existence of a single gene on mitochondrial DNA that controls the biosynthesis of the two respiratory enzymes.
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PMID:Assembly of the mitochondrial membrane system. XIX. Genetic characterization of mit- mutants with deficiencies in cytochrome oxidase and coenzyme qh2-cytochrome c reductase. 18 77


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