Biomaterial Database

DT diaphorase [NAD(P)H: (quinone acceptor) oxidoreductase] facilitates redox cycling of menadione in channel catfish (Ictalurus punctatus) cytosol. 1992

B M Hasspieler, and R T Di Giulio

Ecotoxicology Laboratory, School of the Environment, Duke University, Durham, North Carolina 27706.

Characteristics of DT diaphorase (NAD(P)H: (quinone acceptor) oxidoreductase, DTD) activity in Ictalurus punctatus and the effect of DTD activity on menadione (MND)-mediated reduction of acetylated cytochrome c (AcC) were examined. DTD activity in cytosols of four organs followed a distinct gradient in the order stomach greater than gill greater than liver greater than posterior kidney. A similar gradient was observed in organ-specific rates of in vitro AcC reduction in the presence of either NADH or NADPH as reducing equivalent. A greater proportion of the AcC reduction rate was sensitive to inhibition by dicoumarol (DC) in organs with relatively high DTD specific activity (e.g., stomach) than in organs with low DTD activity (e.g., kidney). No such trend was observed in the superoxide dismutase (SOD)-sensitive proportion of AcC reduction rates. DTD was observed to contribute to MND-mediated superoxide production to a greater extent in organs with high DTD activity than in organs with low DTD activity. DC-sensitive (i.e., DTD-mediated) AcC reduction was observed to increase with organ-specific DTD activity, and the majority of the AcC reduction rate was inhibitable by SOD. These findings demonstrate a direct contribution by DTD activity to MND-mediated superoxide production in this in vitro system. The role of I. punctatus DTD as a possible deleterious agent in quinone metabolism and implications regarding the traditional conception of DTD as a detoxifying enzyme are discussed.

UI	MeSH Term	Description	Entries
D007059	Ictaluridae	A family of North American freshwater CATFISHES. It consists of four genera (Ameiurus, Ictalurus, Noturus, Pylodictis,) comprising several species, two of which are eyeless.	Ameiurus,Catfish, Channel,Channel Catfish,Ictalurus,Bullhead Catfishes,Catfishes, Channel,Channel Catfishes,Ictalurus punctatus,Noturus,Pylodictis,Pylodictus,Catfishes, Bullhead
D008058	Dihydrolipoamide Dehydrogenase	A flavoprotein containing oxidoreductase that catalyzes the reduction of lipoamide by NADH to yield dihydrolipoamide and NAD+. The enzyme is a component of several MULTIENZYME COMPLEXES.	Lipoamide Dehydrogenase,NAD Diaphorase,NADH Diaphorase,Diaphorase (Lipoamide Dehydrogenase),Dihydrolipoyl Dehydrogenase,Glycine Decarboxylase Complex L-Protein,L-Protein, Glycine Decarboxylase Complex,Lipoamide Dehydrogenase, Valine,Lipoic Acid Dehydrogenase,Lipoyl Dehydrogenase,Valine Lipoamide Dehydrogenase,Dehydrogenase, Dihydrolipoamide,Dehydrogenase, Dihydrolipoyl,Dehydrogenase, Lipoamide,Dehydrogenase, Lipoic Acid,Dehydrogenase, Lipoyl,Dehydrogenase, Valine Lipoamide,Diaphorase, NAD,Diaphorase, NADH,Glycine Decarboxylase Complex L Protein
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
D003574	Cytochrome c Group	A group of cytochromes with covalent thioether linkages between either or both of the vinyl side chains of protoheme and the protein. (Enzyme Nomenclature, 1992, p539)	Cytochromes Type c,Group, Cytochrome c,Type c, Cytochromes
D003600	Cytosol	Intracellular fluid from the cytoplasm after removal of ORGANELLES and other insoluble cytoplasmic components.	Cytosols
D004305	Dose-Response Relationship, Drug	The relationship between the dose of an administered drug and the response of the organism to the drug.	Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D014812	Vitamin K	A lipid cofactor that is required for normal blood clotting. Several forms of vitamin K have been identified: VITAMIN K 1 (phytomenadione) derived from plants, VITAMIN K 2 (menaquinone) from bacteria, and synthetic naphthoquinone provitamins, VITAMIN K 3 (menadione). Vitamin K 3 provitamins, after being alkylated in vivo, exhibit the antifibrinolytic activity of vitamin K. Green leafy vegetables, liver, cheese, butter, and egg yolk are good sources of vitamin K.
D015219	Substrate Cycling	A set of opposing, nonequilibrium reactions catalyzed by different enzymes which act simultaneously, with at least one of the reactions driven by ATP hydrolysis. The results of the cycle are that ATP energy is depleted, heat is produced and no net substrate-to-product conversion is achieved. Examples of substrate cycling are cycling of gluconeogenesis and glycolysis pathways and cycling of the triglycerides and fatty acid pathways. Rates of substrate cycling may be increased many-fold in association with hypermetabolic states resulting from severe burns, cold exposure, hyperthyroidism, or acute exercise.	Futile Cycling,Futile Cycles,Futile Substrate Cycles,Futile Substrate Cycling,Cycle, Futile,Cycle, Futile Substrate,Cycles, Futile,Cycles, Futile Substrate,Cycling, Futile,Cycling, Futile Substrate,Cycling, Substrate,Cyclings, Futile,Cyclings, Futile Substrate,Cyclings, Substrate,Futile Cycle,Futile Cyclings,Futile Substrate Cycle,Futile Substrate Cyclings,Substrate Cycle, Futile,Substrate Cycles, Futile,Substrate Cycling, Futile,Substrate Cyclings,Substrate Cyclings, Futile
D015262	Xenobiotics	Chemical substances that are foreign to the biological system. They include naturally occurring compounds, drugs, environmental agents, carcinogens, insecticides, etc.	Xenobiotic