{"doi":"10.1073/pnas.1121040109","title":"Heme-copper terminal oxidase using both cytochrome\n                    <i>c</i>\n                    and ubiquinol as electron donors","abstract":"<jats:p>\n                    The cytochrome\n                    <jats:italic>c</jats:italic>\n                    oxidase Cox2 has been purified from native membranes of the hyperthermophilic eubacterium\n                    <jats:italic>Aquifex aeolicus</jats:italic>\n                    . It is a cytochrome\n                    <jats:italic>ba</jats:italic>\n                    <jats:sub>3</jats:sub>\n                    oxidase belonging to the family B of the heme-copper containing terminal oxidases. It consists of three subunits, subunit I (CoxA2, 63.9 kDa), subunit II (CoxB2, 16.8 kDa), and an additional subunit IIa of 5.2 kDa. Surprisingly it is able to oxidize both reduced cytochrome\n                    <jats:italic>c</jats:italic>\n                    and ubiquinol in a cyanide sensitive manner. Cox2 is part of a respiratory chain supercomplex. This supercomplex contains the fully assembled cytochrome\n                    <jats:italic>bc</jats:italic>\n                    <jats:sub>1</jats:sub>\n                    complex and Cox2. Although direct ubiquinol oxidation by Cox2 conserves less energy than ubiquinol oxidation by the cytochrome\n                    <jats:italic>bc</jats:italic>\n                    <jats:sub>1</jats:sub>\n                    complex followed by cytochrome\n                    <jats:italic>c</jats:italic>\n                    oxidation by a cytochrome\n                    <jats:italic>c</jats:italic>\n                    oxidase, ubiquinol oxidation by Cox2 is of advantage when all ubiquinone would be completely reduced to ubiquinol, e.g., by the sulfide∶quinone oxidoreductase, because the cytochrome\n                    <jats:italic>bc</jats:italic>\n                    <jats:sub>1</jats:sub>\n                    complex requires the presence of ubiquinone to function according to the Q-cycle mechanism. In the case that all ubiquinone has been reduced to ubiquinol its reoxidation by Cox2 will enable the cytochrome\n                    <jats:italic>bc</jats:italic>\n                    <jats:sub>1</jats:sub>\n                    complex to resume working.\n                  </jats:p>","journal":"Proceedings of the National Academy of 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Zwicker","orcid":null,"position":3,"is_corresponding":false},{"id":186890,"name":"Michael Karas","orcid":null,"position":4,"is_corresponding":false},{"id":186891,"name":"Bernd Brutschy","orcid":null,"position":5,"is_corresponding":false},{"id":186892,"name":"Guohong Peng","orcid":null,"position":6,"is_corresponding":false},{"id":186893,"name":"Hartmut Michel","orcid":null,"position":7,"is_corresponding":false},{"id":186886,"name":"Ye Gao","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"base_score":3.5263605246161616,"endowment":3.5263605246161616,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"22334648","pmcid":"PMC3295305","openalex_id":"https://openalex.org/W2169163193","authors":[],"funders":[],"total_grants":0,"fwci":1.2091,"citation_percentile":0.78681552,"influential_citations":1,"citation_trend":[{"year":2012,"count":5},{"year":2013,"count":1},{"year":2015,"count":3},{"year":2016,"count":2},{"year":2018,"count":3},{"year":2019,"count":3},{"year":2020,"count":1},{"year":2021,"count":3},{"year":2022,"count":4},{"year":2023,"count":2},{"year":2024,"count":4},{"year":2025,"count":1},{"year":2026,"count":1}],"oa_status":"bronze","license":null,"oa_locations":[{"url":"https://www.pnas.org/content/pnas/109/9/3275.full.pdf","host_type":"journal"},{"url":"https://www.pnas.org/content/pnas/109/9/3275.full.pdf","host_type":"BRONZE"},{"url":"https://www.pnas.org/content/pnas/109/9/3275.full.pdf","host_type":"publisher"},{"url":"https://pnas.org/doi/pdf/10.1073/pnas.1121040109","host_type":"publisher"},{"url":"https://doi.org/10.1073/pnas.1121040109","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/22334648","host_type":"repository"},{"url":"https://www.ncbi.nlm.nih.gov/pmc/articles/3295305","host_type":"repository"}],"fields_of_study":["Photosynthetic Processes and Mechanisms","Mitochondrial Function and Pathology","Microbial Fuel Cells and Bioremediation","Chemistry","Medicine","Biology","Amino Acid Sequence","Bacterial Proteins","Chemoautotrophic Growth","Copper","Cyanides","Cytochromes c","Electron Transport","Electron Transport Complex IV","Electrons","Energy Metabolism","Heme","Molecular Sequence Data","Multienzyme Complexes","Oxidation-Reduction","Protein Subunits","Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization","Ubiquinone"],"mesh_terms":["Amino Acid Sequence","Bacterial Proteins","Copper","Cyanides","Electron Transport Complex IV","Electron Transport","Electrons","Energy Metabolism","Heme","Molecular Sequence Data","Multienzyme Complexes","Oxidation-Reduction","Ubiquinone","Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization","Protein Subunits","Cytochromes c","Chemoautotrophic Growth"],"keywords":["Ubiquinol","Cytochrome c oxidase","Chemistry","Cytochrome","Copper","Heme","Oxidase test","Biochemistry","Cytochrome c","Electron transport chain","Coenzyme Q – cytochrome c reductase","Enzyme","Mitochondrion","Organic chemistry"],"sdg_mappings":[{"sdg_number":0,"sdg_label":"Clean water and sanitation"}],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[{"name":"gen"}],"source":"live","citation_network_status":"fetched"},"created_at":"2026-06-10T18:42:43.142677Z","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":[]}