scholarly journals LOCALIZATION OF Na+, K+-ATPASE AND OTHER ENZYMES IN TELEOST PSEUDOBRANCH

1973 ◽  
Vol 57 (3) ◽  
pp. 675-688 ◽  
Author(s):  
Leslie A. Dendy ◽  
Russell L. Deter ◽  
Charles W. Philpott
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Specific Activity ◽  
Kinetic Properties ◽  
Sedimentation Analysis ◽  
Marker Enzymes ◽  
Lagodon Rhomboides ◽  
Particle Population ◽  
P Fraction ◽  
Sodium And Potassium

In an effort to determine the subcellular localization of sodium- and potassium-activated adenosine triphosphatase (Na+, K+-ATPase) in the pseudobranch of the pinfish Lagodon rhomboides, this tissue was fractionated by differential centrifugation and the activities of several marker enzymes in the fractions were measured. Cytochrome c oxidase was found primarily in the mitochondrial-light mitochondrial (M+L) fraction. Phosphoglucomutase appeared almost exclusively in the soluble (S) fraction. Monoamine oxidase was concentrated in the nuclear (N) fraction, with a significant amount also in the microsomal (P) fraction but little in M+L or S. Na+, K+-ATPase and ouabain insensitive Mg2+-ATPase were distributed in N, M+L, and P, the former having its highest specific activity in P and the latter in M+L. Rate sedimentation analysis of the M+L fraction indicated that cytochrome c oxidase and Mg2+-ATPase were associated with a rapidly sedimenting particle population (presumably mitochondria), while Na+, K+-ATPase was found primarily in a slowly sedimenting component. At least 75% of the Na+, K+-ATPase in M+L appeared to be associated with structures containing no Mg2+-ATPase. Kinetic properties of the two ATPases were studied in the P fraction and were typical of these enzymes in other tissues. Na+, K+-ATPase activity was highly dependent on the ratio of Na+ and K+ concentrations but independent of absolute concentrations over at least a fourfold range.

scholarly journals The mechanism for the ATP-induced uncoupling of respiration in mitochondria of the yeast Saccharomyces cerevisiae

1995 ◽  
Vol 307 (3) ◽  
pp. 657-661 ◽  
Author(s):  
S Prieto ◽  
F Bouillaud ◽  
E Rial
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Membrane Potential ◽  
Cytochrome C ◽  
Oxidative Phosphorylation ◽  
Cytochrome C Oxidase ◽  
Kinetic Properties ◽  
Yeast Saccharomyces Cerevisiae ◽  
Saccharomyces Cerevisiae Mitochondria ◽  
Low Efficiency ◽  
Respiratory Chain Activity

We have recently reported that ATP induces an uncoupling pathway in Saccharomyces cerevisiae mitochondria [Prieto, Bouillaud, Ricquier and Rial (1992) Eur. J. Biochem. 208, 487-491]. The presence of this pathway would explain the reported low efficiency of oxidative phosphorylation in S. cerevisiae, and may represent one of the postulated energy-dissipating mechanisms present in these yeasts. In this paper we demonstrate that ATP exerts its action in two steps: first, at low ATP/Pi ratios, it increases the respiratory-chain activity, probably by altering the kinetic properties of cytochrome c oxidase. Second, at higher ATP/Pi ratios, an increase in membrane permeability leads to a collapse in membrane potential. The ATP effect on cytochrome c oxidase corroborates a recent report showing that ATP interacts specifically with yeast cytochrome oxidase, stimulating its activity [Taanman and Capaldi (1993) J. Biol. Chem. 268, 18754-18761].

scholarly journals ATP binding to bovine heart cytochrome c oxidase. A photoaffinity labelling study

1986 ◽  
Vol 234 (1) ◽  
pp. 241-243 ◽  
Author(s):  
C Montecucco ◽  
G Schiavo ◽  
R Bisson
Keyword(s):  
Cytochrome C ◽  
Binding Site ◽  
Cytochrome C Oxidase ◽  
Nucleotide Binding ◽  
Nucleotide Binding Site ◽  
Regulatory Role ◽  
Atp Binding ◽  
Kinetic Properties ◽  
Bovine Heart ◽  
Enzyme Subunits

ATP influences the kinetic properties of cytochrome c oxidase. A photoactivatable radioactive ATP analogue was used to localize the nucleotide-binding site on the bovine heart enzyme. Subunits IV and VIII were specifically labelled, suggesting that these two nuclear-coded polypeptides may play a regulatory role on the oxidase functions.

scholarly journals Isoforms of human cytochrome-c oxidase. Subunit composition and steady-state kinetic properties

1991 ◽  
Vol 199 (3) ◽  
pp. 615-622 ◽  
Author(s):  
Andre B. P. KUILENBURG ◽  
Henk L. DEKKER ◽  
Coby BOGERT ◽  
Popko NIEBOER ◽  
Bob F. GELDER ◽  
...  
Keyword(s):  
Steady State ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Subunit Composition ◽  
Kinetic Properties ◽  
Oxidase Subunit ◽  
Steady State Kinetic ◽  
Human Cytochrome ◽  
State Kinetic ◽  
Human Cytochrome C

scholarly journals Canine submandibular-gland hyaluronidase. Identification and subcellular distribution

1968 ◽  
Vol 110 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Y. H. Tan ◽  
J. M. Bowness
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Submandibular Gland ◽  
High Speed ◽  
Specific Activity ◽  
Mitochondrial Fraction ◽  
Product Formation ◽  
Triton X ◽  
Submandibular Saliva ◽  
Testicular Hyaluronidase

1. Submandibular glands from four species of mammal have been shown to contain a hyaluronidase active at acid pH; glands from dog and cat had a much higher content of this enzyme than has been found in other sources. 2. Product formation from hyaluronate after 24hr. incubation was almost the same as with testicular hyaluronidase, indicating that the enzyme is an endo-poly-β-hexosaminidase. 3. When submandibular-gland homogenates were fractionated by the scheme developed for liver by de Duve, Pressman, Gianetto, Wattiaux & Appelmans (1955), all the enzymes assayed, except cytochrome c oxidase, were found to occur partly in the soluble fraction and partly in the particulate fractions. Among the particular fractions, the highest specific activity was found in the heavy-mitochondrial fraction for cytochrome c oxidase, in the microsomal fraction for alkaline phosphatase and in the light-mitochondrial fraction for acid phosphatase, β-N-acetylhexosaminidase and acid-active hyaluronidase. 4. Release of the enzyme activity from the sedimentable fractions occurred in 0·1% Triton X-100 or after high-speed homogenization. 5. Stimulation of dogs by pilocarpine was found to decrease the hyaluronidase content of the submandibular gland by 5% and to cause the occurrence of a corresponding amount of acid-active hyaluronidase in the submandibular saliva. 6. The results are discussed in relation to the subcellular localization of hyaluronidase.

Bioenergetic remodeling during cellular differentiation: changes in cytochrome c oxidase regulation do not affect the metabolic phenotype

2004 ◽  
Vol 82 (3) ◽  
pp. 391-399 ◽  
Author(s):  
Carrie N Lyons ◽  
Scot C Leary ◽  
Christopher D Moyes
Keyword(s):  
Nitric Oxide ◽  
Reactive Oxygen Species ◽  
Cytochrome C ◽  
Oxidative Phosphorylation ◽  
Cytochrome C Oxidase ◽  
Oxidative Metabolism ◽  
Specific Activity ◽  
Reactive Oxygen ◽  
Metabolic Phenotype ◽  
Oxygen Species

Myogenesis induces mitochondrial proliferation, a decrease in reactive oxygen species (ROS) production, and an increased reliance upon oxidative phosphorylation. While muscles typically possess 20%–40% excess capacity of cytochrome c oxidase (COX), undifferentiated myoblasts have only 5%–20% of the mitochondrial content of myotubes and muscles. We used two muscle lines (C2C12, Sol8) and 3T3-L1 pre-adipocytes to examine if changes in COX regulation or activity with differentiation cause a shift in metabolic phenotype (i.e., more oxidative, less glycolytic, less ROS). COX activity in vivo can be suppressed by its inhibitor, nitric oxide, or sub-optimal substrate (cytochrome c) concentrations. Inhibition of nitric oxide synthase via L-NAME had no effect on the respiration of adherent undifferentiated cells, although it did stimulate respiration of myoblasts in suspension. While cytochrome c content increased during differentiation, there was no correlation with respiratory rate or reliance on oxidative metabolism. There was no correlation between COX specific activity and oxidative metabolism between cell type or in relation to differentiation. These studies show that, despite the very low activities of COX, undifferentiated myoblasts and pre-adipocytes possess a reserve of COX capacity and changes in COX with differentiation do not trigger the shift in metabolic phenotype.Key words: oxidative phosphorylation, myogenesis, nitric oxide, reactive oxygen species, cytochrome c oxidase.

scholarly journals Changes in enzyme activities and distributions during glucose de-repression and respiratory adaptation of anaerobically grown Saccharomyces carlsbergensis

1973 ◽  
Vol 132 (3) ◽  
pp. 609-621 ◽  
Author(s):  
T. G. Cartledge ◽  
D. Lloyd
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Respiration Rate ◽  
Enzyme Activities ◽  
Specific Activity ◽  
Antimycin A ◽  
Saccharomyces Carlsbergensis ◽  
Whole Cells ◽  
Nadh Cytochrome ◽  
A Minor

1. During anaerobic glucose de-repression the respiration rate of whole cells of Saccharomyces carlsbergensis remained constant and was insensitive to antimycin A but was inhibited by 30% by KCN. Aeration of cells for 1 h led to increased respiration rate which was inhibited by 80% by antimycin A or KCN. 2. Homogenates were prepared from sphaeroplasts of anaerobically grown, glucose de-repressed cells and the distribution of marker enzymes was investigated after zonal centrifugation on sucrose gradients containing MgCl2. These homogenates contained no detectable cytochrome c oxidase or catalase activity. The complex density distributions of NADH– and NADPH–cytochrome c oxidoreductases and adenosine triphosphatase(s) [ATPase(s)] were very different from those of anaerobically grown, glucose-repressed cells. 3. The specific activity of total ATPase was lowered and sensitivity to oligomycin decreased from 58 to 7% during de-repression. 4. Cytochrome c oxidase and catalase activities were detectable in homogenates of cells after 10min aeration. Zonal centrifugation indicated complex, broad sedimentable distributions of all enzyme activities assayed; the peaks of activity were at 1.27g/ml. 5. Centrifugation of homogenates of cells adapted for 30min and 3 h indicated a shift of density of the major sedimentable peak from 1.25g/ml (30min) to 1.235g/ml (3 h). After 30min adaptation a minor zone of oligomycin-sensitive ATPase and 15% of the total cytochrome c oxidase activities were detected at ρ=1.12g/l; these particles together with those of higher density containing cytochrome c oxidase, ATPase and NADH–cytochrome c oxidoreductase activities were all sedimented at 105g-min. 6. Electron microscopy indicated that the mitochondria-like structures of anaerobically grown, glucose-de-repressed cells were similar to those of repressed cells. After 10min of respiratory adaptation highly organized mitochondria were evident which resembled the condensed forms of mitochondria of aerobically grown, glucose-de-repressed cells. High-density zonal fractions of homogenates of cells after adaptation also contained numerous electron-dense vesicles 0.05–0.2μm in diameter. 7. The possibility that the `promitochondria' of anaerobically grown cells may not be the direct structural precursors of fully functional mitochondria is discussed.

scholarly journals Transient kinetics of subunit-III-depleted cytochrome c oxidase

1986 ◽  
Vol 234 (3) ◽  
pp. 569-572 ◽  
Author(s):  
F Malatesta ◽  
G Antonini ◽  
P Sarti ◽  
M Brunori
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Flash Photolysis ◽  
Order Rate Constant ◽  
Kinetic Properties ◽  
Transient Kinetics ◽  
Rate Limiting Step ◽  
Subunit Iii ◽  
The Stability ◽  
Rate Limiting

Cytochrome c oxidase from ox heart was depleted of subunit III and its transient kinetic properties studied by stopped-flow and flash photolysis. It was found that the overall mechanism of electron transfer is very similar for subunit-III-depleted and native oxidase, although significant differences in some kinetic parameters have been detected. These include the second-order rate constant for cytochrome c oxidation and the rate-limiting step of the overall process. Moreover, at low cytochrome c/oxidase ratios (where the number of reducing equivalents is insufficient), the rate of reoxidation of cytochrome a was found to be very slow, even in air, and in fact for the subunit-III-depleted enzyme is even slower than for the native oxidase. The stability of reduced cytochrome a excludes the likelihood that removal of subunit III leads to a new O2-binding site, and the result may be relevant to the lowered vectorial H+/e- stoichiometry. The subunit-III-depleted oxidase can be pulsed under appropriate conditions and its combination with CO is unchanged, as shown by kinetic experiments and difference spectroscopy.

The influence of chronic ethanol feeding to rats on liver mitochondrial membrane structure and function

1980 ◽  
Vol 58 (10) ◽  
pp. 1147-1155 ◽  
Author(s):  
E. A. Hosein ◽  
Hung Lee ◽  
Ilan Hofmann
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Rat Liver ◽  
Mitochondrial Membrane ◽  
Membrane Structure ◽  
Membrane Lipids ◽  
Specific Activity ◽  
Structure And Function ◽  
Membrane Structure And Function ◽  
And Function

Arrhenius plots were generated on the activity of rat liver mitochondrial cytochrome c oxidase from Metrecal–sucrose fed controls and Metrecal–alcohol fed experimentals. Chronic alcohol feeding resulted in diminished specific activity of cytochrome c oxidase and abolition of the discontinuity temperature at 17.5 °C found in the controls. Twenty-four hours after alcohol withdrawal, a discontinuity temperature reappeared at 14.4 °C; at 48 h it increased to 22.6 °C and returned to normal (17.4 °C) at 72 h. Such liver mitochondria also showed a decreased capacity to oxidize the acetyl group of acetyl carnitine immediately following prolonged alcohol feeding. When the assay was performed following withdrawal from alcohol 24 h later, oxidation was enhanced and this effect persisted for another 48 h. These latter results revealed a diminished capacity of such mitochondria to oxidize short chain fatty acids during alcohol feeding and the reverse during alcohol withdrawal.These results, complemented by thermographic data obtained through differential scanning calorimetry (DSC) reinforced the view that chronic alcoholic feeding induced adaptive changes in the fluidity of rat liver mitochondrial membrane lipids. Moreover, they demonstrated that in the microenvironment of the membrane-bound enzymes on withdrawal from ethanol, the membrane readapts to the new conditions without alcohol. This involved modulation of membrane structure and function and at the same time demonstrated a role for the membrane in the expression of tolerance and functional dependence on alcohol.

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