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 effect of chronic ethanol intoxication on oxidative phosphorylation in the rat brain mitochondrial fraction was examined. Moreover, electron microscopy was used to verify the quantitative composition of the fraction and for examination of ultrastructural changes in the mitochondria. The experiments were carried out with 60 rats receiving, beside the normal diet, ethyl alcohol according to a modified RATCLIFFE model. In isolated rat brain mitochondria the NAD-dependent oxidation of substrates (glutamate + malate) was decreased. The phosphorylation index ADP/0 and the respiratory control ratio (RCR) in rat brain mitochondria from ethanol-treated rats were unchanged in the presence of both succinate and glutamate + malate. Chronic ethanol feeding did not induce any changes of succinate dehydrogenase and cytochrome oxidase activities in solubilised mitochondria fractions of rat brain. Electron microscopy studies revealed that mitochondria from control animals retained their outer and inner membranes, whereas those from rats given ethanol were almost always swollen and some were disrupted. In mitochondrial fractions isolated from ethanol-intoxicated rats an increase was observed of contaminating elements i.e. axons and synaptosomes of various sizes. It should be stressed that the mitochondria located inside synaptosomes and axons were unchanged. The composition of the fractions was quantitatively evaluated and confirmed the diminution of "free" mitochondria in the experimental fractions in favour of "bound" mitochondria which mainly occurred in the synaptosomes with preserved metabolic activity. On the basis of electron microscopy studies it could be suggested that ethanol intoxication causes the damage of some mitochondria, which become more sensitive to mechanical destruction during isolation procedure, and they do not sediment together with the fraction of normal ones. The absence of "free" mitochondria in pellets explains the spurious lack of disturbances in the energy metabolism of brain mitochondria after chronic ethanol intoxication.
...
PMID:Ultrastructural and biochemical studies of the brain and other organs in rat after chronic ethanol administration. III. Influence of ethanol intoxication on oxidative phosphorylation of the rat brain mitochondria with ultrastructural and morphometric evaluation of mitochondrial fraction). 624 56

Unilateral chemical lesion of the nucleus locus coeruleus in rats produced unilateral depletion of ipsilateral cortical norepinephrine. Norepinephrine depletion was not associated with changes in "resting" metabolic balance of the cerebral cortex, as determined by in situ reflection spectrophotometry of the redox state of cytochrome oxidase. Norepinephrine depletion, however, caused slowing of the transient metabolic response to sudden increases in energy demand produced by direct cortical electrical stimulation. The effect was apparent in the redox state of both cytochrome oxidase and NAD, the latter being measured, also in situ, by reflection microfluorometry. These results demonstrate that norepinephrine has a role in modulating the response to increased metabolic demand in the cerebral cortex. Norepinephrine may mediate its effect by potentiating Na+, K+-ATPase or through its effects on vascular reactivity, or both.
...
PMID:Norepinephrine depletion alters cerebral oxidative metabolism in the "active" state. 626 26

Various examples illustrating the use of spectrophotometry and fluorometry in epithelia are presented. The first example uses the redox level of cytochrome aa3, measured spectrophotometrically as an index of tissue anoxia in cortical tubules and slices from the rabbit kidney. In the second example the redox level is used to measure the kinetics of aerobic energy production during transition to anoxia in the midgut of the tobacco hornworm. In the third application, the redox level of mitochondrial NADH is measured fluorometrically in a cortical tubule suspension from the rabbit kidney. Inhibition of active transport work causes reduction of NAD whereas increased work elicits oxidation of NAD, both occurring as expected from mitochondrial transitions to a lesser or more active state, respectively. Another use of NADH fluorescence is the determination of the relative effectiveness of metabolic substrates to deliver reducing equivalents to the respiratory chain in a particular tissue. Redox changes in mitochondrial NAD may be used to distinguish between primary metabolic and primary transport effects of hormones, drugs, and changes in the state of the organism. Finally, examples are provided of the use of an intracellular pH-sensitive dye and an extracellular calcium-sensitive dye in kidney tubules.
...
PMID:Use of noninvasive fluorometry and spectrophotometry to study epithelial metabolism and transport. 627 32

The respiration of mitochondria isolated from mixed skeletal muscles of hindlimbs of rats flown for 18.5 days on Cosmos-936 was investigated polarographically. At R + 10 hours the rate of mitochondrial respiration in different metabolic states during the oxidation of succinic acid and NAD-dependent substrates declined. The enzyme activity of mitochondrial cytochrome oxidase and cytosol lactate dehydrogenase diminished. At R + 25 days both aerobic and anaerobic oxidative processes increased, thus leading to the recovery of the parameters (sometimes they not only returned to the norm but exceeded it).
...
PMID:[Energy reactions in the skeletal muscles of rats following space flight on the Kosmos-936 biosatellite]. 629 7

relationship between levels of cAMP and catabolite repression in yeasts has been investigated. Strains of Saccharomyces cerevisiae, Schizosaccharomyces pombe and Kluyveromyces fragilis were used. The yeasts were grown on different carbon sources to attain various degrees of repression. Galactose repressed as much as glucose, while maltose was less effective. Full derepression was achieved with ethanol. The enzymes tested were fructose-bisphosphatase, malate dehydrogenase, glutamate dehydrogenase (NAD dependent), cytochrome oxidase and isocitrate lyase (this last enzyme was found to be absent in Schizosaccharomyces). The levels of cAMP were 2-3 times higher in the repressed conditions than in the derepressed ones. It is therefore concluded that in yeasts catabolite repression is not mediated by a lowering of the intracellular concentration of cAMP.
...
PMID:Catabolite repression in yeasts is not associated with low levels of cAMP. 632 8

In porcine interareolar placental epithelia, the following enzymes were demonstrated by histochemical methods after 30, 58, 80, 100, and 110 d of pregnancy, respectively: beta-N-acetylhexosaminidase, beta-galactosidase, beta-glucuronidase, alpha-mannosidase, acid phosphatase, alkaline phosphatase, nonspecific esterases, cytochrome oxidase, 5-nucleotidase, leucine aminopeptidase, adenosine triphosphatase, diaphorases (NADH, NADPH), glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, succinate dehydrogenase, isocitrate dehydrogenase (NAD, NADP), beta-hydroxybutyrate dehydrogenase, glycero-3-phosphate dehydrogenase, NAD-glycero-3-phosphate dehydrogenase, glutamate dehydrogenase (NAD, NADP), lactate dehydrogenase. The results show that most of the enzyme activities remained almost unchanged during the period of investigation. Only G-6-PDH and 6-PGDH activities increased within the uterine epithelium and nonspecific esterase activity within uterine as well as chorionic epithelia during the 2nd half of pregnancy. Within chorionic and uterine epithelia, hydrolases but not dehydrogenases demonstrated a higher activity at the bases of chorionic villi as compared to the apices and flanks of the latter. The action and influence of the demonstrated enzymes on metabolism, energy transfer, secretory, and resorptive activities of chorionic and uterine epithelia are discussed.
...
PMID:[Enzyme histochemical studies of the swine placenta. Histoptics of enzymes in interareolar placental epithelia]. 643 35

Fluorescence of NADH and vascular volume of the brain cortex of chloralose-anesthetized cats were measured by surface fluororeflectometry. A cranial window and superfusion technique was elaborated for the topical inhibition of mitochondrial electron transport in the brain cortex by amytal (inhibits at site I) and cyanide (inhibits at site III). The changes in NAD/NADH redox state and CVV evoked by these electron transport inhibitors were compared with those elicited by anoxic anoxia. Amytal (10(-3)-10(-1) M) and cyanide (10(-5)-10(-2) M) resulted in a concentration-dependent and reversible increase in cortical NAD reduction and vascular volume, but the cerebrocortical vessels were almost completely dilatated long before maximum NAD reduction was reached. Cyanide at 10(-2) M increased cortical NAD reduction and vascular volume as much as anoxic anoxia. Amytal at 10(-1) M induced approximately half of the NAD reduction evoked by 10(-2) M cyanide or anoxic anoxia, but resulted in only slightly less vasodilatation than that following cyanide and anoxic anoxia. Since amytal inhibits mitochondrial electron transport at site I--and cyanide and anoxia at site III--but induces a comparable degree of vasodilatation, it is concluded that cytochrome oxidase cannot be the single molecular oxygen sensor in the brain cortex.
...
PMID:A simple cranial window technique for optical monitoring of cerebrocortical microcirculation and NAD/NADH redox state. Effect of mitochondrial electron transport inhibitors and anoxic anoxia. 668 84

A method was developed for selecting cytochrome-deficient mutants of yeast Candida parapsilosis; the method is based on determining the rate of inhibition of oxygen uptake by benzhydroxamic acid, an inhibitor of cyanide-resistant oxidase in the cells of preliminarily obtained yeast mutants. The mutant (C. parapsilosis bhas-1) lacks cytochrome a+a3, contains the same quantity of cytochrome b as the wild strain and a twice as low quantity of cytochrome c. In contrast to the wild strain, the mutant does not grow on ethanol for the first two days but, being cultivated further (up to 5 days), in a medium with ethanol, it resumes its capability to utilize ethanol as a carbon and energy source. Prolonged cultivation in the medium with ethanol induces the biosynthesis of cytochrome oxidase while cytochrome a+a3 is not induced in a medium supplied with glucose. The biomass accumulated by the mutant in the medium with glucose is twice as low comparing to that of the wild strain. The oxidative activity of the mutant mitochondria involves cyanide, resistant oxidase. The mitochondria of the mutant oxidize NAD-dependent substrates, NADH, NADPH, succinate, alpha-glycerophosphate, ethanol and lactate. The mitochondria have a low respiratory control and phosphorylate ADP while oxidizing NAD-dependent substrates, ethanol and lactate, but not alpha-glycerophosphate, succinate, NADH and NADPH.
...
PMID:[Selection method and the characteristics of a cytochrome (a+a3)-deficient mutant of Candida parapsilosis yeasts]. 702 49

A delay in the onset of accumulation of methylene hexadecanoic acid could be engendered in Pseudomonas denitrificans growing under limited oxygen conditions when the concentration of citrate but not the concentration of succinate in the medium was increased from 0.1 to 0.5%. Ascorbate, which specifically reduced a cytochrome component possessing a maximum absorbance at 551 nm, partially inhibited the accumulation of methylene hexadecanoic acid under conditions which otherwise led to maximal production. Limiting terminal cytochrome oxidase activity by controlling the oxygen supply, or by the use of low concentrations of the oxidase inhibitors cyanide or azide also prevented the accumulation of the fatty acid regardless of the nature or concentration of carbon source in the medium. Measurement of the levels of ATP, NAD and NADH as well as the steady state of reduction of respiratory components in vivo showed that the onset of accumulation of methylene hexadecanoic acid could be specifically correlated with the state of reduction of respiratory components. The uniqueness of succinate respiration in promoting the synthesis of cyclopropane synthetase (unsaturated-phospholipid methyltransferase (EC 2.1.1.16) under limited oxygen conditions could therefore be assigned to the high degree of oxidation of respiratory components observed under this condition.
...
PMID:Studies on cyclopropane fatty acid synthesis. Correlation between the state of reduction of respiratory components and the accumulation of methylene hexadecanoic acid by Pseudomonas denitrificans. 728 25

Cations caused a decrease in the apparent Km and an increase in the Vmax. for the oxidation of exogenous NADH by both Jerusalem-artichoke (Helianthus tuberosus) and Arum maculatum (cuckoo-pint) mitochondria prepared and suspended in a low-cation medium (approximately or equal to 1 mM-K+). In Arum mitochondria the addition of cations caused a much greater stimulation of the oxidation of NAD(P)H via the cytochrome oxidase pathway than via the alternative, antimycin-insensitive, pathway. This shows that cations affected a rate-limiting step in the electron-transport chain at or beyond ubiquinone, the branch-point of electron transport in plant mitochondria. The effects were only dependent on the valency of the cation (efficiency C3+ greater than C2+ greater than C+) and not on its chemical nature, which is consistent with the theory of the diffuse layer. The results are interpreted to show that the screening of fixed negative membrane changes on lipids and protein complexes causes a conformational change in the mitochondrial inner membrane, leading to a change in a rate-limiting step of NAD(P)H oxidation. More specifically, it is proposed that screening removes electrostatic restrictions on lateral diffusion and thus accelerates diffusion-limited steps in electron transport.
...
PMID:Charge screening by cations affects the conformation of the mitochondrial inner membrane. A study of exogenous MAD(P)H oxidation in plant mitochondria. 731 73


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

---