Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.6.5.3 (complex I)
 8,901 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Parkinson's disease (PD) is a common degenerative disease, but its etiology is still unknown. However, since the discovery of MPTP, many investigators have been interested in the mitochondrial function in PD. We investigated mitochondrial functions in PD patients using the methods which have successfully been applied to mitochondrial myopathies (MM), i.e. assay of lactate and pyruvate, measurement of muscle mitochondrial respiratory enzyme activities and Southern blot analysis of muscle mitochondrial DNA. Parkinson's disease patients did not differ from controls in the mean blood and CSF (cerebrospinal fluid) lactate and pyruvate levels at the basal resting state or during an aerobic exercise. But mitochondrial complex I activity of the skeletal muscle was significantly decreased in PD. In the Southern blot analysis, we could not find major deletions or insertions of mitochondrial DNA in PD. Our studies disclosed a differential mitochondrial impairment between PD and MM. We discuss the implication of our observation.
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PMID:Is Parkinson's disease a mitochondrial disorder? 157 31

Mitochondria are a major source of superoxide, formed by the one-electron reduction of oxygen during electron transport. Superoxide initiates oxidative damage to phospholipids, proteins and nucleic acids. This damage may be a major cause of degenerative disease and aging. In isolated mitochondria, superoxide production on the matrix side of the membrane is particularly high during reversed electron transport to complex I driven by oxidation of succinate or glycerol 3-phosphate. Reversed electron transport and superoxide production from complex I are very sensitive to proton motive force, and can be strongly decreased by mild uncoupling of oxidative phosphorylation. Both matrix superoxide and the lipid peroxidation product 4-hydroxy-trans-2-nonenal can activate uncoupling through endogenous UCPs (uncoupling proteins). We suggest that superoxide releases iron from aconitase, leading to a cascade of lipid peroxidation and the release of molecules such as hydroxy-nonenal that covalently modify and activate the proton conductance of UCPs and other proteins. A function of the UCPs may be to cause mild uncoupling in response to matrix superoxide and other oxidants, leading to lowered proton motive force and decreased superoxide production. This simple feedback loop would constitute a self-limiting cycle to protect against excessive superoxide production, leading to protection against aging, but at the cost of a small elevation of respiration and basal metabolic rate.
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PMID:Mitochondrial superoxide and aging: uncoupling-protein activity and superoxide production. 1577 23