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)

A new rapid method for fractionation of crude synaptosomes (postmitochondrial pellet, P2) on a discontinuous 4-step Percoll gradient is described. The homogeneity and integrity of the 5 major subcellular fractions were determined by analysis of the distribution of protein, lactate dehydrogenase, cytochrome oxidase, pyruvate dehydrogenase, synapsin I (a synaptic vesicle marker) and the myelin basic proteins. The biochemical results were substantiated by quantitative electron microscopy. Fractions 3, 4 and 5 were enriched in synaptosomes and contained 19.7, 40.6 and 19.5% of the intact, identifiable synaptosomes in P2, respectively. Fraction 1 was enriched in membranous material, fraction 2 in myelin and fraction 5 in extrasynaptosomal mitochondria. The synaptosomes in fractions 3, 4 and 5 differed in their size, and their content of mitochondria, synapsin I and neurotransmitters. These results suggest that partial separation of different pools of synaptosomes has been achieved. The synaptosomes in fractions 3, 4 and 5 are viable, as they take up calcium, phosphate and noradrenaline; they are metabolically normal as judged by their ability to perform protein phosphorylation and they respond normally to depolarization by increasing calcium uptake, protein phosphorylation and neurotransmitter release. The synaptosomes in fraction 4 are relatively homogeneous and appear to be free of contamination from lysed synaptosomes and synaptic plasma membranes. This constitutes a major advantage of the Percoll method over traditional procedures which involve centrifugation to equilibrium. We have therefore confirmed (J. Neurochem., 43 (1984) 1114-1123) the advantages of Percoll use over traditional procedures, while further reducing the time taken, and extended our analysis to show that the present procedure provides a fractionation of synaptosomes into different pools of viable synaptosomes.
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PMID:A rapid method for isolation of synaptosomes on Percoll gradients. 301 Dec 5

Van Etten, James L. (University of Illinois, Urbana), H. Peter Molitoris, and David Gottlieb. Changes in fungi with age. II. Respiration and respiratory enzymes of Rhizoctonia solani and Sclerotium bataticola. J. Bacteriol. 91:169-175. 1966.-The rate of respiration of Rhizoctonia solani and Sclerotium bataticola decreased with age. This decrease in respiratory rate might be produced by a decrease in the specific activity of one or more enzymes involved in carbohydrate metabolism. Specific activities in cell-free extracts were measured for most of the enzymes in the hexose monophosphate shunt, Embden-Meyerhof-Parnas pathway, tricarboxylic acid cycle, and terminal electron-transport system. In addition, glucose oxidase, isocitritase, and malic enzyme were measured. In R. solani, increases in activity with age occurred for hexokinase, alpha-glycerolphosphate dehydrogenase, malic dehydrogenase, and cytochrome oxidase. Decreases occurred for phosphohexokinase, aconitase, nicotinamide adenine dinucleotide-specific isocitric dehydrogenase, reduced nicotinamide adenine dinucleotide oxidase, and at least one of the enzymes between 3-phosphoglycerate and pyruvate. In S. bataticola, increases in activity with age were observed for phosphohexokinase, pyruvic dehydrogenase, fumarase, malic dehydrogenase, and malic enzyme, whereas none of the enzymes decreased. The specific activities of the remaining enzymes did not change with age in either fungus.
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PMID:Changes in fungi with age. II. Respiration and respiratory enzymes of Rhizoctonia solani and Sclerotium bataticola. 428 29

We will present 8 children with progressive infantile or juvenile poliodystrophy (Alpers' disease), associated with a defect in pyruvate metabolism. Laboratory studies showed elevated levels of lactate in CSF and, in 4 children, elevated levels in serum. Histopathologic studies revealed lipid storage in liver and/or muscle tissue, sometimes myopathy with abnormal mitochondria and slight axonal degeneration in the peripheral nerve. Autopsy showed the characteristics of progressive poliodystrophy with degeneration and loss of neurons. Electron microscopy of cerebral cortex showed no mitochondrial abnormalities in neurons or astroglia. Biochemical studies in muscle and/or liver and/or cerebral tissue showed different deficiencies in pyruvate metabolism: in the pyruvate dehydrogenase complex, in the second part of the citric acid cycle (after the oxoglutarate dehydrogenase complex), in the NADH oxidation, in cytochrome aa3 and in pyruvate carboxylase.
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PMID:Defects in citric acid cycle and the electron transport chain in progressive poliodystrophy. 643 1

Lesions to the entorhinal afferent of the hippocampus in rats caused marked changes in calcium transport into mitochondria. Pyruvate-supported calcium transport into mitochondria from the denervated hippocampus was decreased to a larger extent than succinate-supported transport, and adenosine triphosphate-supported transport was not significantly modified. Although cytochrome oxidase and succinate dehydrogenase activities were not significantly changed by entorhinal lesions, pyruvate flux through pyruvate dehydrogenase was significantly decreased, and this effect was correlated with changes in pyruvate-supported calcium transport. The active portion of pyruvate dehydrogenase decreased, whereas total pyruvate dehydrogenase was not modified. These data suggest that denervation might initiate dendritic atrophy and subsequent growth responses by modifying calcium regulation through a change in the phosphorylation of pyruvate dehydrogenase.
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PMID:Entorhinal cortex lesions induce a decreased calcium transport in hippocampal mitochondria. 707 88

Protein degradation rates for liver subcellular and submitochondrial fractions from neonatal (8-day), weanling (25-day) and adult rats were estimated by the double-isotope method with NaH14CO3 and [3H] arginine as the radiolabelled precursors [Dice, Walker, Byrne & Cardiel (1978) Proc. Natl. Acad. Sci. U.S.A. 75, 2093-2097]. Decreased protein degradation rates were found during post-natal development for homogenate, nuclear, mitochondrial, lysosomal and microsomal proteins. A decrease in degradation rates for the immunoisolated subunits of monoamine oxidase and pyruvate dehydrogenase was also observed in neonatal and weanling rats respectively. The results suggest coordinate degradation of the subunits of the multi-subunit enzyme pyruvate dehydrogenase. Pyruvate dehydrogenase has a faster rate of degradation in adult rat liver than does cytochrome oxidase. Data analysis suggests heterogeneity of protein degradation rates in the mitochondrial outer membrane and intermembrane space fractions at each developmental stage but not in the mitochondrial inner membrane or matrix fractions. Results obtained for protein degradation rates in adult rat liver by the method of Burgess, Walker & Mayer [(1978) Biochem. J. 176, 919-926] in general confirmed the results obtained for the adult rat liver by the above method. No evidence of a subunit-size relationship for protein degradation was found for proteins in any subcellular or submitochondrial fraction.
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PMID:Protein degradation in rat liver during post-natal development. 730 3

Subacute necrotizing encephalomyelopathy (Leigh's syndrome) is a rare neurodegenerative disease in the adult. The precise metabolic defect is unknown, but abnormalities of a mitochondrial enzyme system related to cytochrome-c oxidase or pyruvate dehydrogenase are described. The clinical picture usually consists of an altered breathing pattern, oculomotor paralysis, other signs of cranial nerve dysfunction, ataxia, myoclonic jerks, nystagmus, generalized seizures, optic atrophy and demyelinating peripheral neuropathy. Hypopnea leads to CO2-retention with consecutive loss of consciousness demanding mechanical ventilation. Respiratory failure is the most frequent cause of death. Here we describe two patients with adult onset Leigh's syndrome and we discuss the longterm treatment strategies including vitamin B1 and CPAP mask.
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PMID:[Adult Leigh syndrome. A rare differential diagnosis of central respiratory insufficiency]. 771 56

Recent studies show that patients presenting with cytochrome oxidase (COX) deficiency in infancy may have reduced mitochondrial DNA (mtDNA) in muscle. The human mitochondrial transcription factor A (h-mtTFA) may be an important regulator of both transcription and replication of mtDNA. h-mtTFA levels were investigated in cell lines which were either free of mtDNA (rho 0) or temporarily depleted by treatment with dideoxycytidine (ddC), and in tissue from three patients with mtDNA depletion and cytochrome oxidase deficiency. h-mtTFA was compared with other mitochondrial proteins such as pyruvate dehydrogenase and porin by Western blotting. The ratio of mtDNA and h-mtTFA mRNA to reference nuclear probes was measured by dual labelling of dot blots. The ratio of mtDNA to nuclear DNA in skeletal muscle was low in muscle in the three patients and in other tissues in one. h-mtTFA was low in cells depleted either permanently or transiently of mtDNA, and this reduction in h-mtTFA roughly paralleled mtDNA levels. Similarly, treatment of rho 0 cell lines with ddC induced a reduction in mtDNA as well as h-mtTFA protein. The relationship between h-mtTFA and mtDNA levels suggests that they may be causally linked. MtDNA depletion was accompanied by an increase in the level of h-mtTFA RNA in the cell lines but low levels in the patient. This suggests that either h-mtTFA regulates mtDNA levels, or that h-mtTFA expression may be regulated by a feedback mechanism initiated by MtDNA Depletion.
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PMID:Deficiency of the human mitochondrial transcription factor h-mtTFA in infantile mitochondrial myopathy is associated with mtDNA depletion. 784 99

We investigated the etiology of Leigh syndrome in 67 Australian cases from 56 pedigrees, 35 with a firm diagnosis and 32 with some atypical features. Biochemical or DNA defects were determined in both groups, ie, 80% in the tightly defined group and 41% in the "Leigh-like" group. Eleven patients had mitochondrial DNA point mutations (nucleotide [nt] 8993 T to G, nt 8993 T to C, or nt 8344 A to G) and 1 Leigh-like patient had a heteroplasmic deletion. Twenty-nine patients had enzyme defects, ie, 13 respiratory chain complex I, 9 complex IV, and 7 pyruvate dehydrogenase complex (PDHC). Complex I deficiency is more common than recognized previously. Six PDHC-deficient patients had mutations in the X-chromosomal gene encoding the E1alpha subunit of PDHC. Parental consanguinity suggested autosomal recessive inheritance in two complex IV-deficient sibships. We found no strong correlation between the clinical features and basic defects. An assumption of autosomal recessive inheritance (frequently made in the past) would have been wrong in nearly one-half (11 of 28 tightly defined and 18 of 41 total patients) of those in whom a cause was found. A specific defect must be identified if reliable genetic counseling is to be provided.
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PMID:Leigh syndrome: clinical features and biochemical and DNA abnormalities. 860 53

We have compared respiratory chain enzyme activities, ATP synthesis, and ATP hydrolysis in cultured fibroblast mitochondria from patients with Leigh syndrome (LS) due to: (i) cytochrome oxidase (COX) deficiency (#6); (ii) pyruvate dehydrogenase complex (PDHC) deficiency (#4); and (iii) maternally inherited LS (MILS) with the T8993G mutation in the ATPase 6 gene of mtDNA (#5). Enzyme activities were normal in patients with MILS and variably decreased in those with COX and PDHC deficiency. ATP hydrolysis was normal or mildly decreased in all three groups. In contrast, ATP synthesis was decreased in all patients but more markedly in those with MILS, and especially with pyruvate/malate as substrate. These studies show that impaired ATP production is the common feature of all three forms of LS, but it is both more severe and more specific in MILS, consistent with the genetic defect.
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PMID:Comparative biochemical studies in fibroblasts from patients with different forms of Leigh syndrome. 883 Jan 76

Disruption of early or late fetal brain development resulting in structural abnormalities may be associated with inborn errors of mitochondrial metabolism. It is common in patients with deficiency of pyruvate dehydrogenase activity and it has sporadically been described in patients with dysfunction of the tricarboxylic acid cycle. Mitochondrial respiratory chain disorders are not commonly known to interfere with early brain development. We describe here a girl with an encephalomyopathy likely to be due to a novel type of deficiency of cytochrome c oxidase (complex IV) activity that presented with severe hypotonia, myoclonic seizures, optic atrophy and elevated lactate concentration in cerebrospinal fluid shortly after birth. Cranial magnetic resonance imaging revealed hypoplasia of the cerebellum with rudimentary cerebellar hemispheres and relative sparing of the vermis. This case suggests that deficiency of cytochrome c oxidase and possibly respiratory chain disorders in general have to be considered in the differential diagnosis of cerebellar hypoplasia.
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PMID:Cerebellar hypoplasia in respiratory chain dysfunction. 889 74


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