Glycerophosphate-dependent hydrogen peroxide production by brown adipose tissue mitochondria and its activation by ferricyanide |
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Authors: | Drahota Zdenek Chowdhury Subir K R Floryk Daniel Mrácek Tomás Wilhelm Jirí Rauchová Hana Lenaz Giorgio Houstek Josef |
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Institution: | (1) Institute of Physiology and Center for Integrated Genomics, Academy of Sciences of the Czech Republic, 142 20 Prague, Czech Republic;(2) Institute of Medical Chemistry and Biochemistry, 2nd Medical Faculty, Charles University, 150 00 Prague, Czech Republic;(3) Department of Biochemistry, Medical School, University of Bologna, 40126 Bologna, Italy |
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Abstract: | Oxidation of glycerophosphate (GP) by brown adipose tissue mitochondria in the presence of antimycin A was found to be accompanied by significant production of hydrogen peroxide. GP-dependent hydrogen peroxide production could be detected by p-hydroxyphenylacetate fluorescence changes or as an antimycin A-insensitive oxygen consumption. One-electron acceptor, potassium ferricyanide, highly stimulated the rate of GP-dependent antimycin A-insensitive oxygen uptake, which was prevented by inhibitors of mitochondrial GP dehydrogenase (mGPDH) or by coenzyme Q(CoQ). GP-dependent ferricyanide-induced peroxide production was also determined luminometrically, using mitochondria or partially purified mGPDH. Ferricyanide-induced peroxide production was negligible, when succinate or NADH was used as a substrate. These results indicate that hydrogen peroxide is produced directly by mGPDH and reflect the differences in the transport of reducing equivalents from mGPDH and succinate dehydrogenase to the CoQ pool. The data suggest that more intensive production of reactive oxygen species may be present in mammalian cells with active mGPDH. |
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Keywords: | brown adipose tissue mitochondrial glycerophosphate dehydrogenase ferricyanide hydrogen peroxide |
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