{"doi":"10.1111/j.1432-1033.1986.tb10073.x","title":"On the oxidation pathways of the mitochondrial <i>bc</i><sub>1</sub> complex from beef heart","abstract":"<jats:p>We have investigated the oxidation of the reduced ubiquinol: cytochrome <jats:italic>c</jats:italic> (<jats:italic>bc</jats:italic><jats:sub>1</jats:sub> complex) isolated from beef heart mitochondria. The oxidation of cytochrome <jats:italic>c</jats:italic><jats:sub>1</jats:sub> by both potassium ferricyanide and cytochrome <jats:italic>c</jats:italic> in the ascorbate‐reduced <jats:italic>bc</jats:italic><jats:sub>1</jats:sub> complex is not a first‐order process. This is taken as evidence that cytochrome <jats:italic>c</jats:italic><jats:sub>1</jats:sub> is in rapid equilibrium with the Rieske iron‐sulphur center. Among the several inhibitors tested, only 5‐<jats:italic>n</jats:italic>‐undecyl‐6‐hydroxy‐4,7‐dioxobenzothiazole and stigmatellin are seen to affect this redox equilibrium between the high‐potential centers of the beef heart <jats:italic>bc</jats:italic><jats:sub>1</jats:sub> complex.</jats:p><jats:p>The oxidation of cytochrome <jats:italic>b</jats:italic> by cytochrome <jats:italic>c</jats:italic> in both the succinate‐reduced and the fully reduced <jats:italic>bc</jats:italic><jats:sub>1</jats:sub> complex is blocked by all the inhibitors tested. This inhibition occurs simultaneoulsy with an acceleration in the oxidation of cytochrome <jats:italic>c</jats:italic><jats:sub>1</jats:sub>, even after extraction of the endogenous ubiquinone which is present in the <jats:italic>bc</jats:italic><jats:sub>1</jats:sub> preparation. Almost complete extraction of ubiquinone from the <jats:italic>bc</jats:italic><jats:sub>1</jats:sub> complex has no effect upon the rapid phase of cytochrome <jats:italic>b</jats:italic> oxidation, nor does it alter the inhibition of cytochrome <jats:italic>b</jats:italic> oxidation by the various inhibitors.</jats:p><jats:p>The oxidation of cytochrome <jats:italic>b</jats:italic> by exogenous ubiquinones is stimualted by myxothiazol and partially inhibited by antimycin. However, the addition of both these inhibitors together completely blocks the oxidation of cytochrome <jats:italic>b</jats:italic> by quinones. In contrast, the simultaneous addition of antimycin and myxothiazol has no such synergistic effect upon the oxidation of cytochrome <jats:italic>b</jats:italic> by cytochrome <jats:italic>c</jats:italic>.</jats:p><jats:p>Our data show that intramolecular electron transfer from cytochrome(s) <jats:italic>b</jats:italic> to the Rieske iron‐sulphur center can take place in the <jats:italic>bc</jats:italic><jats:sub>1</jats:sub> complex without involvement of endogenous ubiquinone‐10. This electron pathway is sensitive to all the inhibitors of the enzyme.</jats:p>","journal":"European Journal of Biochemistry","year":1986,"id":37691,"datarank":1.362503766392822,"base_score":3.1780538303479458,"endowment":3.1780538303479458,"self_citation_contribution":0.47670807455219194,"citation_network_contribution":0.8857956918406299,"self_endowment_contribution":0.47670807455219194,"citer_contribution":0.8857956918406299,"corpus_percentile":null,"corpus_rank":null,"citation_count":23,"citer_count":14,"citers_with_citation_signal":14,"citers_with_endowment":14,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":188348,"name":"Ah‐Lim TSAI","orcid":null,"position":1,"is_corresponding":false},{"id":188349,"name":"Graham PALMER","orcid":null,"position":2,"is_corresponding":false},{"id":188350,"name":"Giorgio LENAZ","orcid":null,"position":3,"is_corresponding":false},{"id":188347,"name":"Mauro DEGLI ESPOSTI","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"base_score":3.1780538303479458,"endowment":3.1780538303479458,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"3023079","pmcid":null,"openalex_id":"https://openalex.org/W1514008659","authors":[],"funders":[{"funder_name":"NIGMS NIH HHS","grant_id":"GM 21332","title":null}],"total_grants":1,"fwci":1.2775,"citation_percentile":0.78872315,"influential_citations":0,"citation_trend":[{"year":2017,"count":1},{"year":2018,"count":1},{"year":2023,"count":1}],"oa_status":"bronze","license":"http://onlinelibrary.wiley.com/termsAndConditions#vor","oa_locations":[{"url":"https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/j.1432-1033.1986.tb10073.x","host_type":"journal"},{"url":"https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/j.1432-1033.1986.tb10073.x","host_type":"BRONZE"},{"url":"https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/j.1432-1033.1986.tb10073.x","host_type":"publisher"},{"url":"https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1432-1033.1986.tb10073.x","host_type":"publisher"},{"url":"https://febs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1432-1033.1986.tb10073.x","host_type":"publisher"},{"url":"https://doi.org/10.1111/j.1432-1033.1986.tb10073.x","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/3023079","host_type":"repository"}],"fields_of_study":["Mitochondrial Function and Pathology","Photosynthetic Processes and Mechanisms","Coenzyme Q10 studies and effects","Chemistry","Medicine","Biology","Animals","Cattle","Cytochrome b Group","Cytochrome c Group","Electron Transport Complex II","Kinetics","Mitochondria, Heart","Multienzyme Complexes","Oxidation-Reduction","Oxidoreductases","Submitochondrial Particles","Succinate Dehydrogenase"],"mesh_terms":["Animals","Cattle","Cytochrome b Group","Cytochrome c Group","Kinetics","Mitochondria, Heart","Multienzyme Complexes","Oxidation-Reduction","Oxidoreductases","Submitochondrial Particles","Succinate Dehydrogenase","Electron Transport Complex II"],"keywords":["Coenzyme Q – cytochrome c reductase","Cytochrome C1","Cytochrome c","Cytochrome","Ubiquinol","Cytochrome b","Chemistry","Cytochrome c oxidase","Cytochrome c peroxidase","Cytochrome b6f complex","Cytochrome P450 reductase","Biochemistry","Antimycin A","Electron transport chain","Mitochondrion","Enzyme","Mitochondrial DNA"],"sdg_mappings":[{"sdg_number":0,"sdg_label":"Clean water and sanitation"}],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-06-10T20:36:59.698587Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}