title: Carbon monoxide-insensitive respiratory chain of Pseudomonas carboxydovorans.
abstract: Experiments employing electron transport inhibitors, room- and low-temperature spectroscopy, and photochemical action spectra have led to a model for the respiratory chain of Pseudomonas carboxydovorans. The chain is branched at the level of b-type cytochromes or ubiquinone. One branch (heterotrophic branch) contained cytochromes b558, c, and a1; the second branch (autotrophic branch) allowed growth in the presence of CO and contained cytochromes b561 and o (b563). Electrons from the oxidation of organic substrates were predominantly channelled into the heterotrophic branch, whereas electrons derived from the oxidation of CO or H2 could use both branches. Tetramethyl-p-phenylenediamine was oxidized via cytochromes c and a exclusively. The heterotrophic branch was sensitive to antimycin A, CO, and micromolar concentrations of cyanide. The autotrophic branch was sensitive to 2-n-heptyl-4-hydroxyquinoline-N-oxide, insensitive to CO, and inhibited only by millimolar concentrations of cyanide. The functioning of cytochrome a1 as a terminal oxidase was established by photochemical action spectra. Reoxidation experiments established the functioning of cytochrome o as an alternative CO-insensitive terminal oxidase of the autotrophic branch.
mesh_terms: D002248:Carbon Monoxide / Q000378:metabolism / Q000494:pharmacology*; D002374:Catalase / Q000378:metabolism; D003573:Cytochrome b Group / Q000378:metabolism; D003574:Cytochrome c Group / Q000378:metabolism; D003580:Cytochromes / Q000378:metabolism*; D004579:Electron Transport / Q000187:drug effects; D029968:Escherichia coli Proteins; D005560:Formate Dehydrogenases / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D008027:Light; D009097:Multienzyme Complexes / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D011549:Pseudomonas / Q000378:metabolism*; D013385:Succinate Dehydrogenase / Q000378:metabolism
chemical_list: D003573:Cytochrome b Group; D003574:Cytochrome c Group; D003580:Cytochromes; D029968:Escherichia coli Proteins; D009097:Multienzyme Complexes; D002248:Carbon Monoxide; D006859:Hydrogen; C017168:cytochrome bo, E coli; D006861:Hydrogen Peroxide; D002374:Catalase; D005560:Formate Dehydrogenases; D013385:Succinate Dehydrogenase; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases