Документ взят из кэша поисковой машины. Адрес
оригинального документа
: http://biochem.bio.msu.ru/publications/publication.php?pubmedID=19645667
Дата изменения: Unknown Дата индексирования: Mon Oct 1 20:47:24 2012 Кодировка: Поисковые слова: hydrogen |
Title: | Site-directed mutagenesis of cytochrome c: reactions with respiratory chain components and superoxide radical. |
Authors: | Pepelina TY; Chertkova RV; Ostroverkhova TV; Dolgikh DA; Kirpichnikov MP; Grivennikova VG; Vinogradov AD |
Publication: | Biochemistry (Mosc). 2009 Jun;74(6):625-32. |
PubmedID | 19645667 |
Abstract | |
Three forms of horse heart cytochrome c with specific substitutions of heme cleft surface located amino acid residues involved in specific interactions with ubiquinol:cytochrome c reductase (complex III) and cytochrome c oxidase (complex IV) were constructed, and their reactions with superoxide radical produced by NADH:ubiquinone reductase (complex I) were studied. The proteins with six (K27E/E69K/K72E/K86E/K87E/E90K and K8E/E62K/E69K/K72E/K86E/K87E) and eight (K8E/K27E/E62K/E69K/K72E/K86E/K87E/E90K) substitutions were inactive in the cytochrome c oxidase reaction, and their reduction rates by complex III were significantly lower than that seen with acetylated cytochrome c. The reduction of these modified cytochromes c under conditions where complex I generates superoxide was almost completely (about 90%) inhibited by superoxide dismutase. The genetically modified cytochromes c are useful analytical reagents for studies on superoxide generation by the mitochondrial respiratory chain. Quantitative comparison of superoxide-mediated cytochrome c reduction with hydrogen peroxide-mediated Amplex Red oxidation suggests that complex I within its native environment (submitochondrial particles) produces both superoxide (~50%) and hydrogen peroxide (~50%). |