Biomaterial Database

Cytochrome a620 in Tetrahymena pyriformis. Reactions with carbon monoxide and oxygen at subzero temperatures and photochemical action spectra. 1982

D Lloyd, and R I Scott, and S W Edwards, and C Edwards, and B Chance

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.

UI	MeSH Term	Description	Entries
D008928	Mitochondria	Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)	Mitochondrial Contraction,Mitochondrion,Contraction, Mitochondrial,Contractions, Mitochondrial,Mitochondrial Contractions
D010100	Oxygen	An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.	Dioxygen,Oxygen-16,Oxygen 16
D010777	Photochemistry	A branch of physical chemistry which studies chemical reactions, isomerization and physical behavior that may occur under the influence of visible and/or ultraviolet light.	Photochemistries
D002248	Carbon Monoxide	Carbon monoxide (CO). A poisonous colorless, odorless, tasteless gas. It combines with hemoglobin to form carboxyhemoglobin, which has no oxygen carrying capacity. The resultant oxygen deprivation causes headache, dizziness, decreased pulse and respiratory rates, unconsciousness, and death. (From Merck Index, 11th ed)	Monoxide, Carbon
D003080	Cold Temperature	An absence of warmth or heat or a temperature notably below an accustomed norm.	Cold,Cold Temperatures,Temperature, Cold,Temperatures, Cold
D003580	Cytochromes	Hemeproteins whose characteristic mode of action involves transfer of reducing equivalents which are associated with a reversible change in oxidation state of the prosthetic group. Formally, this redox change involves a single-electron, reversible equilibrium between the Fe(II) and Fe(III) states of the central iron atom (From Enzyme Nomenclature, 1992, p539). The various cytochrome subclasses are organized by the type of HEME and by the wavelength range of their reduced alpha-absorption bands.	Cytochrome
D004579	Electron Transport	The process by which ELECTRONS are transported from a reduced substrate to molecular OXYGEN. (From Bennington, Saunders Dictionary and Encyclopedia of Laboratory Medicine and Technology, 1984, p270)	Respiratory Chain,Chain, Respiratory,Chains, Respiratory,Respiratory Chains,Transport, Electron
D006420	Hemeproteins	Proteins that contain an iron-porphyrin, or heme, prosthetic group resembling that of hemoglobin. (From Lehninger, Principles of Biochemistry, 1982, p480)	Hemeprotein,Heme Protein,Heme Proteins,Protein, Heme,Proteins, Heme
D013053	Spectrophotometry	The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.
D013347	Subcellular Fractions	Components of a cell produced by various separation techniques which, though they disrupt the delicate anatomy of a cell, preserve the structure and physiology of its functioning constituents for biochemical and ultrastructural analysis. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p163)	Fraction, Subcellular,Fractions, Subcellular,Subcellular Fraction