Biomaterial Database

The photoreduction of nicotinamide-adenine dinucleotide by chromatophore fractions from Rhodospirillum rubrum. 1972

R Govindjee, and C Sybesma

The photoreduction of nicotinamide-adenine dinucleotide (NAD(+)), catalyzed by chromatophore fractions from young (1 day) and old (4-5 days) cultures of Rhodospirillum rubrum, was measured in the presence of either succinate or 2,6-dichlorophenol indophenol (DPIP) and an excess of ascorbate. The time-course of photoreduction in the succinate system suggested a "reversed electron flow" from the donor to NAD(+) mediated by a high energy intermediate produced by a light-induced, cyclic electron transport in the chromatophore fractions. The effects of the uncoupler carbonyl cyanide [p-(trifluoromethoxy)phenyl]hydrazone (FCCP) and of the inhibitors antimycin A and 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO) were consistent with this interpretation. The time-course of NAD(+) photoreduction in the presence of DPIP and ascorbate suggested a direct, light-induced electron transport from the donor to the acceptor. We cannot yet distinguish between a model in which the same reaction center is utilized in the photoreduction by both donor systems (the reaction center component P-870 may relate to two primary acceptors at different redox potential levels) and a model in which each photoreducing system is driven by its own reaction center component.

UI	MeSH Term	Description	Entries
D007215	Indophenol	A deep blue dye (with the formula OC6H4NC6H4OH) used to detect AMMONIA in a common test called the Berthelot's reaction and to detect PARACETAMOL by spectrophotometry.
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008956	Models, Chemical	Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.	Chemical Models,Chemical Model,Model, Chemical
D009243	NAD	A coenzyme composed of ribosylnicotinamide 5'-diphosphate coupled to adenosine 5'-phosphate by pyrophosphate linkage. It is found widely in nature and is involved in numerous enzymatic reactions in which it serves as an electron carrier by being alternately oxidized (NAD+) and reduced (NADH). (Dorland, 27th ed)	Coenzyme I,DPN,Diphosphopyridine Nucleotide,Nadide,Nicotinamide-Adenine Dinucleotide,Dihydronicotinamide Adenine Dinucleotide,NADH,Adenine Dinucleotide, Dihydronicotinamide,Dinucleotide, Dihydronicotinamide Adenine,Dinucleotide, Nicotinamide-Adenine,Nicotinamide Adenine Dinucleotide,Nucleotide, Diphosphopyridine
D010084	Oxidation-Reduction	A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).	Redox,Oxidation Reduction
D010636	Phenols	Benzene derivatives that include one or more hydroxyl groups attached to the ring structure.
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
D011804	Quinolines
D003486	Cyanides	Inorganic salts of HYDROGEN CYANIDE containing the -CN radical. The concept also includes isocyanides. It is distinguished from NITRILES, which denotes organic compounds containing the -CN radical.	Cyanide,Isocyanide,Isocyanides
D005650	Fumarates	Compounds based on fumaric acid.	Fumarate,Fumaric Acid Ester,Fumaric Acid Esters,Fumarate Esters,Acid Ester, Fumaric,Acid Esters, Fumaric,Ester, Fumaric Acid,Esters, Fumarate,Esters, Fumaric Acid