title: Cytochrome a620 in Tetrahymena pyriformis. Reactions with carbon monoxide and oxygen at subzero temperatures and photochemical action spectra.
abstract: 1. Mitochondria-enriched fractions of the ciliate protozoan Tetrahymena pyriformis ST contained CO-reacting cytochromes b560 and a620. 2. A non-photodissociable oxygen-containing compound of cytochrome a620 was formed in whole cell suspensions at -114 degrees C after photolysis of CO in the presence of 200 microM-O2. 3. Electron transport, indicated by the oxidation of cytochrome a620 and cytochrome c, occurred at temperatures higher than -72 degrees C. 4. Photochemical action spectra for the relief of respiratory inhibition of whole cells by CO obtained by using a liquid dye laser indicate that the only CO-reacting terminal oxidase detectable was cytochrome a620. 5. It is concluded that the alternative electron transport chains in this organism utilize non-cytochrome terminal oxidases.
mesh_terms: D002248:Carbon Monoxide / Q000378:metabolism*; D003080:Cold Temperature; D017936:Cytochrome a Group; D003580:Cytochromes / Q000378:metabolism*; D004579:Electron Transport; D006420:Hemeproteins / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D010777:Photochemistry; D015800:Protozoan Proteins; D013053:Spectrophotometry; D013347:Subcellular Fractions / Q000378:metabolism; D013769:Tetrahymena pyriformis / Q000378:metabolism*
chemical_list: D017936:Cytochrome a Group; D003580:Cytochromes; D006420:Hemeproteins; D015800:Protozoan Proteins; C036213:cytochrome a620, Tetrahymena pytriformis; D002248:Carbon Monoxide; D010100:Oxygen