Biomaterial Database

Reductive activity of a manganese-dependent peroxidase from Phanerochaete chrysosporium. 1993

N Chung, and M M Shah, and T A Grover, and S D Aust

Utah State University Biotechnology Center, Logan 84322-4705.

A manganese-dependent peroxidase (MnP) from Phanerochaete chrysosporium catalyzed the reduction of cytochrome c in a reaction mixture containing H2O2, Mn(II)-tartrate, and p-hydroquinone. Electron spin resonance studies have shown that the hydroquinone-dependent reductive activity of MnP is due to the benzosemiquinone formed upon the one-electron oxidation of p-hydroquinone by Mn(III)-tartrate, which is formed upon the oxidation of Mn(II) by MnP. The reductive activity increased linearly with an increase in the concentration of p-hydroquinone. The reductive activity was also observed using other hydroquinones such as methylhydroquinone, 2,5-dimethylhydroquinone, and trimethylhydroquinone. The apparent Km values for Mn(II) and H2O2 for the hydroquinone-dependent reductive activity were similar to those for oxidative reactions of MnP. A stoichiometry study showed that about 1.5 mol of cytochrome c was reduced per mole of H2O2 consumed. The stoichiometry decreased with an increase in the concentration of H2O2. The optimal pH for the reductive activity was 5.0, approximately the physiological pH of the fungus. The reduction of cytochrome c was also observed using a quinone and cellobiose:quinone oxidoreductase isolated from the extracellular medium of the fungus.

UI	MeSH Term	Description	Entries
D007527	Isoenzymes	Structurally related forms of an enzyme. Each isoenzyme has the same mechanism and classification, but differs in its chemical, physical, or immunological characteristics.	Alloenzyme,Allozyme,Isoenzyme,Isozyme,Isozymes,Alloenzymes,Allozymes
D007700	Kinetics	The rate dynamics in chemical or physical systems.
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
D010544	Peroxidases		Ovoperoxidase
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
D004578	Electron Spin Resonance Spectroscopy	A technique applicable to the wide variety of substances which exhibit paramagnetism because of the magnetic moments of unpaired electrons. The spectra are useful for detection and identification, for determination of electron structure, for study of interactions between molecules, and for measurement of nuclear spins and moments. (From McGraw-Hill Encyclopedia of Science and Technology, 7th edition) Electron nuclear double resonance (ENDOR) spectroscopy is a variant of the technique which can give enhanced resolution. Electron spin resonance analysis can now be used in vivo, including imaging applications such as MAGNETIC RESONANCE IMAGING.	ENDOR,Electron Nuclear Double Resonance,Electron Paramagnetic Resonance,Paramagnetic Resonance,Electron Spin Resonance,Paramagnetic Resonance, Electron,Resonance, Electron Paramagnetic,Resonance, Electron Spin,Resonance, Paramagnetic
D006873	Hydroquinones	Derivatives of hydroquinone (1,4-dihydrobenzene) made by reduction of BENZOQUINONES.	Quinol,p-Dihydroxybenzenes,para-Dihydroxybenzenes,Quinols,p Dihydroxybenzenes,para Dihydroxybenzenes
D001487	Basidiomycota	A phylum of fungi that produce their sexual spores (basidiospores) on the outside of the basidium. It includes forms commonly known as mushrooms, boletes, puffballs, earthstars, stinkhorns, bird's-nest fungi, jelly fungi, bracket or shelf fungi, and rust and smut fungi.	Basidiomycetes,Basidiomycete,Basidiomycotas
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