scholarly journals Effects of flavonoids on xanthine oxidation as well as on cytochrome c reduction by milk xanthine oxidase.

1986 ◽  
Vol 32 (6) ◽  
pp. 635-642 ◽  
Author(s):  
Masayoshi IIO ◽  
Yoshimi ONO ◽  
Setsumi KAI ◽  
Michi FUKUMOTO
Keyword(s):  
Cytochrome C ◽  
Xanthine Oxidase ◽  
Cytochrome C Reduction

Multiple Bovine Myoglobin Inhibition of Cytochrome c Reduction by Xanthine Oxidase

Nature ◽  
1964 ◽  
Vol 201 (4922) ◽  
pp. 928-929 ◽  
Author(s):  
J. R. QUINN ◽  
A. M. PEARSON
Keyword(s):  
Cytochrome C ◽  
Xanthine Oxidase ◽  
Cytochrome C Reduction

scholarly journals Superoxide dismutase-inhibitible reduction of cytochrome c by the alloxan radical. Implications for alloxan cytotoxicity

1982 ◽  
Vol 207 (3) ◽  
pp. 609-612 ◽  
Author(s):  
C C Winterbourn
Keyword(s):  
Superoxide Dismutase ◽  
Cytochrome C ◽  
Xanthine Oxidase ◽  
Reduced Glutathione ◽  
Direct Reaction ◽  
Cytochrome C Reduction

Cytochrome c was reduced when superoxide was generated from xanthine oxidase in the presence of alloxan, and by the reaction of alloxan and with reduced glutathione. In each case, most of the reduction was inhibited by superoxide dismutase, but considerably more enzyme was required than with superoxide alone. This indicates that the superoxide dismutase-inhibitible cytochrome c reduction was mainly due to a direct reaction with the alloxan radical, and implies that other reactions that are inhibited by superoxide dismutase could be due to either alloxan radicals or superoxide.

Superoxide, Xanthine Oxidase and Platelet Reactions: Further Studies on Mechanisms by which Oxidants Influence Platelets

1981 ◽  
Vol 45 (03) ◽  
pp. 290-293 ◽  
Author(s):  
Peter H Levine ◽  
Danielle G Sladdin ◽  
Norman I Krinsky
Keyword(s):  
Superoxide Dismutase ◽  
Cytochrome C ◽  
Xanthine Oxidase ◽  
Direct Effect ◽  
Platelet Function ◽  
Experimental Conditions ◽  
Release Reaction

SummaryIn the course of studying the effects on platelets of the oxidant species superoxide (O- 2), Of was generated by the interaction of xanthine oxidase plus xanthine. Surprisingly, gel-filtered platelets, when exposed to xanthine oxidase in the absence of xanthine substrate, were found to generate superoxide (O- 2), as determined by the reduction of added cytochrome c and by the inhibition of this reduction in the presence of superoxide dismutase.In addition to generating Of, the xanthine oxidase-treated platelets display both aggregation and evidence of the release reaction. This xanthine oxidase induced aggreagtion is not inhibited by the addition of either superoxide dismutase or cytochrome c, suggesting that it is due to either a further metabolite of O- 2, or that O- 2 itself exerts no important direct effect on platelet function under these experimental conditions. The ability of Of to modulate platelet reactions in vivo or in vitro remains in doubt, and xanthine oxidase is an unsuitable source of O- 2 in platelet studies because of its own effects on platelets.

Experimental Studies and Computational Modeling on Cytochrome C Reduction by Quercetin: the role of oxidability and binding affinity

2021 ◽  
pp. 130995
Author(s):  
Gabriel Zazeri ◽  
Ana Paula Ribeiro Povinelli ◽  
Nathalia M. Pavan ◽  
Daniella Romano de Carvalho ◽  
Carmen Lúcia Cardoso ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Computational Modeling ◽  
Binding Affinity ◽  
Experimental Studies ◽  
Cytochrome C Reduction

scholarly journals The importance of the interdomain hinge in intramolecular electron transfer in flavocytochrome b2

1993 ◽  
Vol 291 (1) ◽  
pp. 89-94 ◽  
Author(s):  
P White ◽  
F D C Manson ◽  
C E Brunt ◽  
S K Chapman ◽  
G A Reid
Keyword(s):  
Electron Transfer ◽  
Steady State ◽  
Cytochrome C ◽  
Kinetic Properties ◽  
Stopped Flow ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Cytochrome C Reductase ◽  
Flavocytochrome B2 ◽  
Cytochrome C Reduction

The two distinct domains of flavocytochrome b2 (L-lactate:cytochrome c oxidoreductase) are connected by a typical hinge peptide. The amino acid sequence of this interdomain hinge is dramatically different in flavocytochromes b2 from Saccharomyces cerevisiae and Hansenula anomala. This difference in the hinge is believed to contribute to the difference in kinetic properties between the two enzymes. To probe the importance of the hinge, an interspecies hybrid enzyme has been constructed comprising the bulk of the S. cerevisiae enzyme but containing the H. anomala flavocytochrome b2 hinge. The kinetic properties of this ‘hinge-swap’ enzyme have been investigated by steady-state and stopped-flow methods. The hinge-swap enzyme remains a good lactate dehydrogenase as is evident from steady-state experiments with ferricyanide as acceptor (only 3-fold less active than wild-type enzyme) and stopped-flow experiments monitoring flavin reduction (2.5-fold slower than in wild-type enzyme). The major effect of the hinge-swap mutation is to lower dramatically the enzyme's effectiveness as a cytochrome c reductase; kcat. for cytochrome c reduction falls by more than 100-fold, from 207 +/- 10 s-1 (25 degrees C, pH 7.5) in the wild-type enzyme to 1.62 +/- 0.41 s-1 in the mutant enzyme. This fall in cytochrome c reductase activity results from poor interdomain electron transfer between the FMN and haem groups. This can be demonstrated by the fact that the kcat. for haem reduction in the hinge-swap enzyme (measured by the stopped-flow method) has a value of 1.61 +/- 0.42 s-1, identical with the value for cytochrome c reduction and some 300-fold lower than the value for the wild-type enzyme. From these and other kinetic parameters, including kinetic isotope effects with [2-2H]lactate, we conclude that the hinge plays a crucial role in allowing efficient electron transfer between the two domains of flavocytochrome b2.

scholarly journals Macrophage variants in oxygen metabolism.

1980 ◽  
Vol 152 (4) ◽  
pp. 808-822 ◽  
Author(s):  
G Damiani ◽  
C Kiyotaki ◽  
W Soeller ◽  
M Sasada ◽  
J Peisach ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Cytochrome C ◽  
Superoxide Anion ◽  
Oxygen Metabolism ◽  
Hexose Monophosphate ◽  
Phagocytic Cells ◽  
Form Complex ◽  
Hexose Monophosphate Shunt ◽  
Cytochrome C Reduction ◽  
Generate Superoxide Anion

Whereas phagocytic cells from normal individuals have the capacity to kill ingested bacteria and parasites, those from patients with several uncommon genetic deficiency diseases are known to be defective in bactericidal activity. Studies on neutrophils of these patients have revealed fundamental defects in their ability to reduce molecular oxygen and metabolize it to superoxide anion, hydrogen peroxide, and oxygen radicals. In the present experiments, we describe a clone of a continuous murine macrophage-like cell line, J774.16, that, upon appropriate stimulation, activates the hexose monophosphate shunt, and produces superoxide anion and hydrogen peroxide. With nitroblue tetrazolium to select against cells capable of being stimulated by phorbol myristate acetate to reduce the dye to polymer--formazan--which is toxic fot cells, we have selected for variants that are defective in oxygen metabolism. Four of these subclones have been characterized and found to be lacking in the ability (a) to generate superoxide anion, as measured by cytochrome c reduction; (b) to produce hydrogen peroxide, as measured by the ability to form complex I with cytochrome c peroxidase; and (c) to be stimulated to oxidize glucose via the hexose monophosphate shunt. These variants appear to represent a useful model for studying the molecular basis for macrophage cytocidal activity.

The mechanism of the reduction of cytochrome c by xanthine oxidase

1967 ◽  
Vol 143 (2) ◽  
pp. 408-415 ◽  
Author(s):  
Saburo Muraoka ◽  
Hiroshi Enomoto ◽  
Mie Sugiyama ◽  
Hidemasa Yamasaki
Keyword(s):  
Cytochrome C ◽  
Xanthine Oxidase
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