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Mitochondrial Enzyme (mitochondrial + enzyme)

Distribution by Scientific Domains

Medical Sciences	40%
Life Sciences	40%

Terms modified by Mitochondrial Enzyme

mitochondrial enzyme activity

Selected Abstracts

In Vivo Labeling of Mitochondrial Complex I (NADH:UbiquinoneOxidoreductase) in Rat Brain Using [3H]Dihydrorotenone

JOURNAL OF NEUROCHEMISTRY, Issue 6 2000
Deepa J. Talpade
Abstract: Defects in mitochondrial energy metabolism have beenimplicated in several neurodegenerative disorders. Defective complex I(NADH:ubiquinone oxidoreductase) activity plays a key role in Leber'shereditary optic neuropathy and, possibly, Parkinson's disease, but there isno way to assess this enzyme in the living brain. We previously described anin vitro quantitative autoradiographic assay using[3H]dihydrorotenone ([3H]DHR) binding to complex I. Wehave now developed an in vivo autoradiographic assay for complex I using[3H]DHR binding after intravenous administration. In vivo[3H]DHR binding was regionally heterogeneous, and brain uptake wasrapid. Binding was enriched in neurons compared with glia, and white matterhad the lowest levels of binding. In vivo [3H]DHR binding wasmarkedly reduced by local and systemic infusion of rotenone and was enhancedby local NADH administration. There was an excellent correlation betweenregional levels of in vivo [3H]DHR binding and the in vitroactivities of complex II (succinate dehydrogenase) and complex IV (cytochromeoxidase), suggesting that the stoichiometry of these components of theelectron transport chain is relatively constant across brain regions. Theability to assay complex I in vivo should provide a valuable tool toinvestigate the status of this mitochondrial enzyme in the living brain andsuggests potential imaging techniques for complex I in humans. [source]

Glutamate Export at the Choroid Plexus in Health, Thiamin Deficiency, and Ethanol Intoxication: Review and Hypothesis

ALCOHOLISM, Issue 8 2008
Peter F. Nixon
Introduction:, The earliest observed effect in the pathogenesis of experimental Wernicke's encephalopathy and of ethanol intoxication in rats is impairment of the blood cerebrospinal fluid (CSF) barrier at the choroid plexus (CP). For an explanation, these observations direct attention to the role of the CP in maintaining glutamate homeostasis in the CSF. Methods:, Characteristics of the CP epithelium (CPE) are reviewed, focusing on its role in removal of glutamate from the CSF and its potential for impairment by ethanol oxidation or by thiamin-deficient glucose oxidation. Results:, The export of glutamate from CSF to blood at the CP is energy dependent, saturable, and stereospecific. However, the incapacity of the CP to convert glutamate to other metabolites makes it vulnerable to glutamate accumulation should ,-ketoglutarate dehydrogenase activity be decreased. Elsewhere ethanol metabolism and thiamin-deficiency independently decrease the activity of this mitochondrial enzyme. We argue that they have the same effect within the mitochondria-rich CPE, thereby decreasing energy production necessary for export of glutamate from CSF to blood; diverting its energy metabolism to further glutamate production; and impairing its blood CSF barrier function. This impairment appears to be mediated by glutamate and is attenuated by MK801 but whether it involves one of the CPE glutamate receptors is yet uncertain. This impairment exposes the CSF and hence the paraventricular brain extracellular fluid to neuroactive substances from the blood, including further glutamate, explaining the paraventricular location of neuropathology in Wernicke's encephalopathy. Other organs normally protected from blood by a barrier are affected also by ethanol abuse and by thiamin deficiency, namely the eye, peripheral nerves, and the testis. Much less is known regarding the function of these barriers. Conclusions:, Impairment of the CP by ethanol intoxication and by thiamin-deficient carbohydrate metabolism has a common, rational explanation that can guide future research. [source]

Perioperative management of a child with short-chain acyl-CoA dehydrogenase deficiency

PEDIATRIC ANESTHESIA, Issue 9 2005
BRIAN TURPIN BS
Summary Short-chain acyl-CoA dehydrogenase (SCAD) is a mitochondrial enzyme that catalyzes the dehydrogenation of short chain fatty acids (4 to 6 carbons in length) thereby initiating the cycle of , -oxidation. This process generates acetyl-CoA, the key substrate for hepatic ketogenesis or ATP production by the Kreb's cycle. A deficiency of SCAD results in the build-up of potentially cytotoxic metabolites including ethylmalonic acid, methylsuccinyl CoA and butyryl-carnitine. The end-organ involvement is heterogeneous, but most commonly includes hypotonia with possible lipid myopathy and developmental delay. Other reported complications include dysmorphic craniofacial features, hypoglycemia, seizures, scoliosis, hypertonia and hyperreflexia, cyclic vomiting and myocardial dysfunction. We present a 23-month-old girl with SCAD deficiency, who required posterior fossa decompression for type 1 Chiari malformation. The potential perioperative implications of SCAD deficiency are reviewed. [source]

Purification, crystallization and data collection of the apoptotic nuclease endonuclease G

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 5 2009
Sei Mee Yoon
Endonuclease G (EndoG) is a mitochondrial enzyme that responds to apoptotic stimuli by translocating to the nucleus and cleaving chromosomal DNA. EndoG is the main apoptotic endonuclease in the caspase-independent pathway. Mouse EndoG without the mitochondrial localization signal (amino-acid residues 1,43) was successfully overexpressed, purified and crystallized using a microbatch method under oil. The initial crystal (type I) was grown in the presence of the detergent CTAB and diffracted to 2.8,Å resolution, with unit-cell parameters a = 72.20, b = 81.88, c = 88.66,Å, , = 97.59° in a monoclinic space group. The crystal contained two monomers in the asymmetric unit, with a predicted solvent content of 46.6%. Subsequent mutation of Cys110 improved the stability of the protein significantly and produced further crystals of types II, III and IV with space groups C2, P41212 (or P43212) and P212121, respectively, in various conditions. This suggests the critical involvement of this conserved cysteine residue in the crystallization process. [source]

Mitochondrial A, A potential cause of metabolic dysfunction in Alzheimer's disease

IUBMB LIFE, Issue 12 2006
Xi Chen
Abstract Deficits in mitochondrial function are a characteristic finding in Alzheimer's disease (AD), though the mechanism remains to be clarified. Recent studies revealed that amyloid , peptide (A,) gains access into mitochondrial matrix, which was much more pronounced in both AD brain and transgenic mutant APP mice than in normal controls. A, progressively accumulates in mitochondria and mediates mitochondrial toxicity. Interaction of mitochondrial A, with mitochondrial enzymes such as amyloid , binding alcohol dehydrogenase (ABAD) exaggerates mitochondrial stress by inhibiting the enzyme activity, releasing reactive oxygen species (ROS), and affecting glycolytic, Krebs cycle and/or the respiratory chain pathways through the accumulation of deleterious intermediate metabolites. The pathways proposed may play a key role in the pathogenesis of this devastating neurodegenerative disorder, Alzheimer's disease. iubmb Life, 58: 686-694, 2006 [source]