Biomaterial Database

Kinetic and inhibition studies on reduction of diphenyl sulfoxide by guinea pig liver aldehyde oxidase. 1986

S Yoshihara, and K Tatsumi

To characterize the properties of diphenyl sulfoxide (DPSO) as a new type of electron acceptor for guinea pig liver aldehyde oxidase (AO), we compared the kinetics of the reductions of DPSO and other classical electron acceptors such as O2 and ferricyanide. The double-reciprocal plot of the 2-hydroxypyrimidine (2-OH PM)-linked DPSO reduction with the highly purified enzyme was biphasic. Similar biphasic plots were obtained with the reductions of other electron acceptors. Only the lower Km value, which was obtained by extrapolation of the plot at lower concentrations of 2-OH PM, was identical with that shown by the freshly prepared crude enzyme. DPSO as well as menadione progressively inhibited the reductions of O2 and ferricyanide with time. Menadione inhibited the DPSO reduction noncompetitively with respect to 2-OH PM and competitively with respect to DPSO, while its mode of inhibition of ferricyanide reduction was uncompetitive for either the electron donor or the acceptor. On the other hand, DPSO showed an uncompetitive and a noncompetitive inhibition of ferricyanide reduction with respect to 2-OH PM and ferricyanide, respectively. These results may indicate that DPSO interacts with the enzyme at the same site as menadione, and thereby when other electron acceptors are present it serves as an actual inhibitor rather than as an electron acceptor for AO.

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
D008892	Milk	The off-white liquid secreted by the mammary glands of humans and other mammals. It contains proteins, sugar, lipids, vitamins, and minerals.	Cow Milk,Cow's Milk,Milk, Cow,Milk, Cow's
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
D006168	Guinea Pigs	A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.	Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea
D000445	Aldehyde Oxidoreductases	Oxidoreductases that are specific for ALDEHYDES.	Aldehyde Oxidoreductase,Oxidoreductase, Aldehyde,Oxidoreductases, Aldehyde
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
D001555	Benzene Derivatives	Organic compounds derived from BENZENE.	Derivatives, Benzene
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.
D014969	Xanthine Oxidase	An iron-molybdenum flavoprotein containing FLAVIN-ADENINE DINUCLEOTIDE that oxidizes hypoxanthine, some other purines and pterins, and aldehydes. Deficiency of the enzyme, an autosomal recessive trait, causes xanthinuria.	Hypoxanthine Oxidase,Hypoxanthine Dehydrogenase,Hypoxanthine-Xanthine Oxidase,Purine-Xanthine Oxidase,Dehydrogenase, Hypoxanthine,Hypoxanthine Xanthine Oxidase,Oxidase, Hypoxanthine,Oxidase, Hypoxanthine-Xanthine,Oxidase, Purine-Xanthine,Oxidase, Xanthine,Purine Xanthine Oxidase