Biomaterial Database

Kinetics and thermodynamics of the molecular mechanism of the reductive half-reaction of xanthine oxidase. 1994

M S Mondal, and S Mitra

Chemical Physics Group, Tata Institute of Fundamental Research, Bombay, India.

The kinetics and thermodynamics of the reductive half-reaction of xanthine oxidase with xanthine as substrate have been investigated by stopped-flow kinetic measurements. The temperature dependence of the steady-state and transient kinetics of the reductive half-reaction reveals the existence of at least three molecular intermediates during this half-reaction. All the microscopic rate constants and the thermodynamic activation parameters of the elementary steps of the reductive half-reaction have been determined for the first time. The microscopic rate constants and the thermodynamic activation parameters of the individual steps show wide variations in their magnitudes. The present work provides the most detailed and incisive description of the reaction of xanthine oxidase with its physiological substrate xanthine.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
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
D002417	Cattle	Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.	Beef Cow,Bos grunniens,Bos indicus,Bos indicus Cattle,Bos taurus,Cow,Cow, Domestic,Dairy Cow,Holstein Cow,Indicine Cattle,Taurine Cattle,Taurus Cattle,Yak,Zebu,Beef Cows,Bos indicus Cattles,Cattle, Bos indicus,Cattle, Indicine,Cattle, Taurine,Cattle, Taurus,Cattles, Bos indicus,Cattles, Indicine,Cattles, Taurine,Cattles, Taurus,Cow, Beef,Cow, Dairy,Cow, Holstein,Cows,Dairy Cows,Domestic Cow,Domestic Cows,Indicine Cattles,Taurine Cattles,Taurus Cattles,Yaks,Zebus
D005260	Female		Females
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
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D013379	Substrate Specificity	A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.	Specificities, Substrate,Specificity, Substrate,Substrate Specificities
D013816	Thermodynamics	A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)	Thermodynamic
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