In respiratory chain

L-selegiline alters the redox state of ubiquinone, suggesting that the flow of electrons is impaired in the respiratory chain. Furthermore, a decrease in ubiquinone levels has been observed, whereas ubiquinol (reduced ubiquinone) concentrations are increased in the striatum. Ubiquinol levels have been shown to augment as a result of impaired mitochondrial respiration. For example, ubiquinol concentrations were demonstrated to increase in tubular kidney cells exposed to complex IV inhibitors and in disease states with defects in respiratory chain components. These results are also consistent with the hypothesis that L-selegiline enhances 02 formation by altering the rate of electron transfer within the respiratory chain leading to increases in SOD activities in the mouse striatum. 

A8344G tRNALys Severe defects in respiratory chain activity M8... 

Rustin P, Chretien D, Bourgeron T, Gerard B, Rotig A, Saudubray JM, Munnich A. Biochemical and molecular investigations in respiratory chain deficiencies. Clin. Chim. Acta 1994 228 35-51. Lopez LC, Schuelke M, Quinzii CM, Kanki T, Rodenburg RJ, Naini A, Dimauro S, Hirano M. Leigh syndrome with... 

B. A. Ackrell. 2000. Progress in understanding structure-function relationships in respiratory chain complex II FEBSLett. 466 1-5. (PubMedl... 

The reduction of NADP" by PSI is therefore catalyzed by an association of a flavoprotein and an Fe-S protein, somewhat in analogy with the dehydrogenases operating in the same redox span in respiratory chains the dissociability of ferredoxin from the complex, however, can assure a large degree of flexibility in the utilization of the reducing power generated by photosynthesis. 

Mitochondrial dysfunction has long been considered to play a central role in the development of cell injury during ischemia-reperfusion and hypoxia-reoxygenation [19]. Besides the inhibition of fatty acid oxidation, mitochondrial energy generation is diminished because of defects in respiratory chain function. Inhi-hition of the FO-Fl-ATPase leading to impaired function of respiratory complex I has been observed in I/R injury. Similar to ischemia, dsplatin has been shown to affed mitochondrial respiratory complexes and func-... 

V y of pyruvate, fatty acids, and other fuels. In many cases, the inhibition of mitochondrial electron transport results in higher than normal levels of lactate and pyruvate in the blood and an increased lactate/pyruvate ratio. NADH oxidation requires the completed transfer of electrons from NADH to O2, and a defect anywhere along the chain will result in the accumulation of NADH and decrease of NAD+. The increase in NADH/NAD inhibits pyruvate dehydrogenase and causes the accumulation of pyruvate. It also increases the conversion of pyruvate to lactate, and elevated levels of lactate appear in the blood. A large number of genetic defects of the proteins in respiratory chain complexes have, therefore, been classified together as "congenital lactic acidosis."... 

Another important function of the kinases is the synthesis of ATP from ADP and energy-rich bound phosphate in substrate-linked phosphorylation (cf. Chapt. XV-7) and in respiratory-chain phosphorylation (Chapt. X-6). ATP hence represents a pool for energy-rich phosphates—and, in a sense, for chemical energy in general. 

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