title: [Two sites of ubisemiquinone binding in mitochondrial succinate oxidase].
abstract: The inhibiting effects of several phenol compounds on electron transfer in the respiratory chain of submitochondrial particles were studied. It was shown that the terminal part of the succinate dehydrogenase complex contains a site, which specifically binds the negatively charged phenols (e. g. pentachlorophenol, 2,4-dibromophenol, 2-methoxy-4,6-dibromophenol). The efficiency of the inhibitor anion binding by this site is increased 12-fold after introduction of a methoxy-group into the o-position of 2,4-dibromophenol. Since this site binds both methoxy- and negatively charged phenol groups, it can also act as a possible site of ubisemiquinone interaction with succinate dehydrogenase. Based on the structural similiarity of the b-c1 complex inhibitors, e. g. antimycin, o-hydroxybenzoic acid amides, 2-hydroxy-3-alkyl-1,4-quinones, and ubisemiquinone, an assumption has been made on possible ubisemiquinone binding between cytochromes b and c1. A structural analysis of phenols inhibiting succinate dehydrogenase and the b-c1 complex revealed that in the region between cytochromes b and c1 there act only the inhimitors which contain: a) a negatively charged phenol group; b) a group comprising a heteroatom with an undepleted electron pair and which can act as a ligand, and c) a hydrophobic residue.
mesh_terms: D000818:Animals; D001665:Binding Sites; D008928:Mitochondria / Q000201:enzymology*; D008929:Mitochondria, Heart / Q000201:enzymology*; D010636:Phenols / Q000494:pharmacology; D011485:Protein Binding; D011809:Quinones; D013329:Structure-Activity Relationship; D013367:Submitochondrial Particles / Q000201:enzymology*; D013385:Succinate Dehydrogenase / Q000378:metabolism*; D014451:Ubiquinone / Q000031:analogs & derivatives*
chemical_list: D010636:Phenols; D011809:Quinones; D014451:Ubiquinone; D013385:Succinate Dehydrogenase; C024989:coenzyme Q10
vernacular_title: Dva tsentra sviazyvaniia ubisemikhinona v suktsinatoksidaze mitokhondriĭ.