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'Xanthine Oxidase' in keywords
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1Author    CandadaiS. RamadossRequires cookie*
 Title    Effects of Vanadate on the Molybdoproteins Xanthine Oxidase and Nitrate Reductase: Kinetic Evidence for Multiple Site Interaction  
 Abstract    The inhibition of the activity o f xanthine oxidase by vanadate was strikingly similar to vanadate inhibition of another molybdoprotein nitrate reductase. Although the main catalytic activity of both enzymes was inhibited, the partial N AD H oxidase activity associated with these enzymes was stimulated several fold. It appears that the metal ion binds at multiple site in both enzymes. In the absence o f any enzymes a combination of vanadium (V) and molybdenum (V) in air was found to oxide NADH rapidly. 
  Reference    Z. Naturforsch. 35c, 702—707 (1980); received June 3 1980 
  Published    1980 
  Keywords    Molybdenum, Vanadium, Nitrate Reductase, Xanthine Oxidase 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0702.pdf 
 Identifier    ZNC-1980-35c-0702 
 Volume    35 
2Author    Regina Volpert, ErichF. ElstnerRequires cookie*
 Title    Biochemical Activities of Propolis Extracts I. Standardization and Antioxidative Properties of Ethanolic and Aqueous Derivatives  
 Abstract    Ethanolic extracts of Propolis are used as antiinflammatory and wound healing drugs since ancient times. In order to facilitate a comparison of different extracts, the standardization on the basis of quantitative determination of prominent components of these extracts has been substituted for simple biochemical "activity" tests. One of these activity tests bases on the in­ hibition of peroxidase-catalyzed oxidation of indole acetic acid indicating the presence of a defined mixture of monophenolic and diphenolic compounds. Other tests (diaphorase-cata-lyzed reductions and xanthine oxidase-catalyzed oxidations) demonstrate significant radical scavenging properties. Water-soluble extracts of propolis exhibit higher antioxidative and inhibitory activities as compared to the ethanolic extract. 
  Reference    Z. Naturforsch. 48c, 851—857 (1993); received June 21/August 161993 
  Published    1993 
  Keywords    Propolis, Peroxidase, Xanthine Oxidase, Diaphorase, Indole Acetic Acid Oxidation 
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 TEI-XML for    default:Reihe_C/48/ZNC-1993-48c-0851.pdf 
 Identifier    ZNC-1993-48c-0851 
 Volume    48 
3Author    E. Horozova, N. Dimcheva, Z. JordanovaRequires cookie*
 Title    Enzymatic and Electrochemical Reactions of Xanthine Oxidase Immobilized on Carbon Materials  
 Abstract    A n optimum way o f immobilizing xanthine oxidase on graphite was found where a redox transformation of the enzyme was observed. The nature o f the redox maxima was hypothe­ sized on the basis of the dependence of the half-wave potential (E p/2) on the pH of the solution. The enzymatic activity of xanthine oxidase adsorbed on two kinds o f soot was studied by the oxidation o f xanthine. The kinetic and activation parameters of the enzyme reaction were determined. 
  Reference    Z. Naturforsch. 52c, 159—164 (1997); received November ll/ 
  Published    1997 
  Keywords    Xanthine Oxidase, Immobilized Enzyme, Carbon Materials, Electrochemical and Catalytic Activity 
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 TEI-XML for    default:Reihe_C/52/ZNC-1997-52c-0159.pdf 
 Identifier    ZNC-1997-52c-0159 
 Volume    52 
4Author    UteR. Ohnert3, W. Erner Schneider5, ErichF. Elstner3Requires cookie*
 Title    Superoxide-Dependent and -Independent Nitrite Formation from Hydroxylamine: Inhibition by Plant Extracts  
 Abstract    Reactive oxygen species such as OH-, peroxynitrite and the non-radical, hypochlorous acid, play outstanding roles in many diseases. The formation of OH-(Fenton-)-type radicals is catalyzed by enzymes such as xanthine oxidase (X O D) via one-electron reduction of m o­ lecular oxygen producing superoxide radical anions (0 2 _). Subsequent transfer of one elec­ tron to hydrogen peroxide by Fe2+ or Cu+-ions yields OH-radicals measurable as ethene release from l-keto-4 methylthiobutyrate (KM B). Xanthine oxidase or activated neutrophils are prominent sources o f this strong oxidant produced at inflammatory sites. Many natural compounds such as salicylates or flavonoids interfere either with the pro­ duction of these activated oxygen species or function as radical scavengers and thus as antiox­ idants. Extracts from willow-bark (Salix spec.) and also other species such as ash-tree (Fraxi-nus spec.) or poplar (Populus spec.) have been used as antiinflammatory drugs since a long time. In this communication we wish to report on model reactions to demonstrate a) the radical scavenging activities of such plant extracts inhibiting ethene release from KMB induced by Fenton-type oxidants and b) the inhibition of the formation of nitrogen monoxide (N O) from hydroxylamine includ­ ing X O D either in the presence or absence of myoglobin (M YO) measurable as nitrite forma­ tion: In the absence of MYO, superoxide dismutase is an excellent inhibitor of nitrite forma­ tion but is inactive in its presence. Extracts from the willow-bark or the drug PhytodolorR, however, are inhibitory both in the presence and absence of MYO. As active principle, the flavonoid rutin included in these extracts is likely to function as one inhibitor of the X O D -mediated reaction. 
  Reference    Z. Naturforsch. 53c, 241 (1998); received December 19 1997/January 29 1998 
  Published    1998 
  Keywords    Reactive O xygen Species, Plant-Extracts, Antioxidants, NO-Formation, Xanthine Oxidase 
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 TEI-XML for    default:Reihe_C/53/ZNC-1998-53c-0241.pdf 
 Identifier    ZNC-1998-53c-0241 
 Volume    53 
5Author    ElenaG. Horozova, NinaD. Dimcheva, ZinaidaJ. JordanovaRequires cookie*
 Title    Study of Xanthine Oxidase Immobilized Electrode Based on Modified Graphite  
 Abstract    Xanthine oxidase (E . C. was immobilized by adsorption on electrochem ically modi­ fied graphite plate to obtain an enzyme electrode. The current of the enzyme electrode in substrate (xanthine) solutions was found to be a result of the electrooxidation of H 20 2 gener­ ated in the enzyme layer. The linearity of the amperometric signal was up to a substrate concentration of 65 ^im at 0.6 V (vs. Ag/A gCl). The response time was 2 minutes. The enzyme electrode preserves 80% of its initial activity after perature. 
  Reference    Z. Naturforsch. 55c, 60—6 (2000); received O ctober 5/Novem ber 10 1999 
  Published    2000 
  Keywords    Xanthine Oxidase, Immobilized Enzyme, Modified Graphite, Hydrogen Peroxide, Enzym e Electrode 
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 TEI-XML for    default:Reihe_C/55/ZNC-2000-55c-0060.pdf 
 Identifier    ZNC-2000-55c-0060 
 Volume    55