Biomaterial Database

Glutathione dependent reduction of alloxan to dialuric acid catalyzed by thioltransferase (glutaredoxin): a possible role for thioltransferase in alloxan toxicity. 1997

M P Washburn, and W W Wells

Department of Biochemistry, Michigan State University, East Lansing 48824, USA.

Recombinant pig liver thioltransferase (rPLTT) catalyzes the reduction of alloxan to dialuric acid by glutathione (GSH). This is the second non-disulfide substrate, after dehydroascorbic acid, described for thioltransferase. The reaction kinetics, measured by a coupled assay including glutathione disulfide reductase and NADPH yielded a Km = 82 microM for alloxan, a k(cat) = 37 s(-1), and a k(cat)/Km = 4.5 x 10(5) M(-1) s(-1). The presence of rPLTT suppressed the competitive formation of compound 305, an alloxan-GSH conjugate of unknown structure, and at GSH concentrations between 0.05 mM and 1.5 mM, oxygen consumption was greater than that recorded in the uncatalyzed reaction. Both superoxide dismutase and catalase inhibited oxygen consumption in 1.0 mM GSH and 0.2 mM alloxan in the presence of rPLTT. This study suggests that thioltransferase (glutaredoxin) plays a significant role in the cytotoxicity of alloxan in vulnerable tissues.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008099	Liver	A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.	Livers
D009249	NADP	Nicotinamide adenine dinucleotide phosphate. A coenzyme composed of ribosylnicotinamide 5'-phosphate (NMN) coupled by pyrophosphate linkage to the 5'-phosphate adenosine 2',5'-bisphosphate. It serves as an electron carrier in a number of reactions, being alternately oxidized (NADP+) and reduced (NADPH). (Dorland, 27th ed)	Coenzyme II,Nicotinamide-Adenine Dinucleotide Phosphate,Triphosphopyridine Nucleotide,NADPH,Dinucleotide Phosphate, Nicotinamide-Adenine,Nicotinamide Adenine Dinucleotide Phosphate,Nucleotide, Triphosphopyridine,Phosphate, Nicotinamide-Adenine Dinucleotide
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
D010088	Oxidoreductases	The class of all enzymes catalyzing oxidoreduction reactions. The substrate that is oxidized is regarded as a hydrogen donor. The systematic name is based on donor:acceptor oxidoreductase. The recommended name will be dehydrogenase, wherever this is possible; as an alternative, reductase can be used. Oxidase is only used in cases where O2 is the acceptor. (Enzyme Nomenclature, 1992, p9)	Dehydrogenases,Oxidases,Oxidoreductase,Reductases,Dehydrogenase,Oxidase,Reductase
D010101	Oxygen Consumption	The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)	Consumption, Oxygen,Consumptions, Oxygen,Oxygen Consumptions
D011506	Proteins	Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.	Gene Products, Protein,Gene Proteins,Protein,Protein Gene Products,Proteins, Gene
D011994	Recombinant Proteins	Proteins prepared by recombinant DNA technology.	Biosynthetic Protein,Biosynthetic Proteins,DNA Recombinant Proteins,Recombinant Protein,Proteins, Biosynthetic,Proteins, Recombinant DNA,DNA Proteins, Recombinant,Protein, Biosynthetic,Protein, Recombinant,Proteins, DNA Recombinant,Proteins, Recombinant,Recombinant DNA Proteins,Recombinant Proteins, DNA
D002374	Catalase	An oxidoreductase that catalyzes the conversion of HYDROGEN PEROXIDE to water and oxygen. It is present in many animal cells. A deficiency of this enzyme results in ACATALASIA.	Catalase A,Catalase T,Manganese Catalase,Mn Catalase
D002384	Catalysis	The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.	Catalyses