scholarly journals Haemichrome formation from haemoglobin subunits by hydrogen peroxide

1978 ◽  
Vol 171 (2) ◽  
pp. 329-335 ◽  
Author(s):  
A Tomoda ◽  
K Sugimoto ◽  
M Suhara ◽  
M Takeshita ◽  
Y Yoneyama
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Glucose Oxidase ◽  
Xanthine Oxidase ◽  
Absorption Spectra ◽  
Human Haemoglobin ◽  
Kinetics Of

The effect of H2O2 on ferrous human haemoglobin subunits (alphash-, betash-, alphapmb- and betapmb-chains) was studied. These chains were easily transformed to haemichrome by the addition of H2O2 or H2O2-generating systems, including glucose oxidase (EC 1.1.3.4) AND XANTHINE OXIDASE (EC 1.2.3.2), and this was ascertained by e.p.r. measurements and by absorption spectra. The changes in these haemoglobin subunits were not inhibited by superoxide dismutase (EC 1.15.1.1), but were decreased by catalase (EC 1.11.1.6). The rate of oxidation of alphapmb-chains was higher than that of alphash-chains, and the rate of oxidation of betapmb-chains was higher than that of betash-chains. Haemichrome was demonstrated to be formed directly from these ferrous chains by the attack by H2O2, and this process did not involve formation of methaemoglobin. On the basis of these findings the kinetics of the reaction between the haemoglobin subunits and H2O2 was studied, and the pathological significance of H2O2 in disorders of erythrocytes such as thalassaemia was discussed.

Nitroalkanes as Reductive Substrates for Flavoprotein Oxidases

1972 ◽  
Vol 27 (9) ◽  
pp. 1052-1053 ◽  
Author(s):  
David J. T. Porter ◽  
Judith G. Voet ◽  
Harold J. Bright
Keyword(s):  
Hydrogen Peroxide ◽  
Amino Acid ◽  
Glucose Oxidase ◽  
Ph Dependence ◽  
Kinetic Mechanism ◽  
Acid Oxidase ◽  
Amino Acid Oxidase ◽  
Kinetics Of ◽  
Oxidase Reaction ◽  
Detailed Kinetic Mechanism

Nitroalkanes have been found to be general reductive substrates for D-amino acid oxidase, glucose oxidase and L-amino acid oxidase. These enzymes show different specificities for the structure of the nitroalkane substrate.The stoichiometry of the D-amino acid oxidase reaction is straightforward, consisting of the production of one mole each of aldehyde, nitrite and hydrogen peroxide for each mole of nitroalkane and oxygen consumed. The stoichiometry of the glucose oxidase reaction is more complex in that less than one mole of hydrogen peroxide and nitrite is produced and nitrate and traces of 1-dinitroalkane are formed.The kinetics of nitroalkane oxidation show that the nitroalkane anion is much more reactive in reducing the flavin than is the neutral substrate. The pH dependence of flavin reduction strongly suggests that proton abstraction is a necessary event in catalysis. A detailed kinetic mechanism is presented for the oxidation of nitroethane by glucose.It has been possible to trap a form of modified flavin in the reaction of D-amino acid oxidase with nitromethane from which oxidized FAD can be regenerated in aqueous solution in the presence of oxygen.

scholarly journals Hemolysis and iodination of erythrocyte components by a myeloperoxidase- mediated system

Blood ◽  
1975 ◽  
Vol 45 (5) ◽  
pp. 699-707 ◽  
Author(s):  
SJ Klebanoff ◽  
RA Clark
Keyword(s):  
Superoxide Dismutase ◽  
Thyroid Hormones ◽  
Glucose Oxidase ◽  
Xanthine Oxidase ◽  
Combined Effect ◽  
Oxidase System ◽  
Generating System

Abstract Erythrocytes are hemolyzed by myeloperoxidase, an H2O2-generating system (glucose + glucose oxidase; hypoxanthine + xanthine oxidase) and an oxidizable cofactor (chloride, iodide, thyroxine, triiodothyronine). The combined effect of chloride and either iodide or the thyroid hormones is greater than additive. Myeloperoxidase can be replaced by lactoperoxidase in the iodide-, thyroxine and triiodothyronine- dependent, but not in the chloride-dependent, systems. Hemolysis is is inhibited by the peroxidase inhibitors, azide and cyanide, and by catalase and is stimulated by superoxide dismutase when the xanthine oxidase system is employed as the source of H2O2. Hemolysis by the iodide-dependent system is associated with the iodination of erythrocyte components.

Oxygen-derived free radicals, endothelium, and responsiveness of vascular smooth muscle

1986 ◽  
Vol 250 (5) ◽  
pp. H815-H821 ◽  
Author(s):  
G. M. Rubanyi ◽  
P. M. Vanhoutte
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Smooth Muscle ◽  
Free Radicals ◽  
Vascular Smooth Muscle ◽  
Xanthine Oxidase ◽  
Isometric Tension ◽  
Oxygen Derived Free Radicals ◽  
Major Shift ◽  
The Right

Experiments were designed to determine the role of oxygen-derived free radicals in modulating contractions of vascular smooth muscle and endothelium-mediated relaxations to acetylcholine. The effects of generating or scavenging these radicals were studied in rings of canine coronary arteries suspended for isometric tension recording. Xanthine oxidase plus xanthine caused relaxations, which were greater in rings with endothelium than in rings without endothelium; the relaxations were not affected by superoxide dismutase or mannitol, but could be prevented by catalase. Xanthine oxidase plus xanthine depressed endothelium-mediated relaxations to acetylcholine; this effect was prevented by superoxide dismutase, but was not affected by catalase or mannitol. Exogenous hydrogen peroxide induced catalase-sensitive relaxations, which were depressed by the removal of the endothelium. Superoxide dismutase evoked catalase-sensitive relaxations only in rings with endothelium. Endothelium-mediated relaxations to acetylcholine were slightly depressed by superoxide dismutase or catalase alone; the combination of the two enzymes or mannitol caused a major shift to the right of the concentration-response curve to acetylcholine. In rings without endothelium, relaxations caused by sodium nitroprusside were not affected by the scavengers (alone or in combination) but were augmented by xanthine oxidase plus xanthine. These data suggest that the endothelium-derived relaxing factor released by acetylcholine is not likely to be an oxygen-derived free radical; hydrogen peroxide has a direct inhibitory action on coronary arterial smooth muscle and triggers endothelium-dependent relaxations; and superoxide anions depress and hydroxyl radicals facilitate endothelium-dependent relaxations caused by activation of muscarinic receptors.

scholarly journals Hemolysis and iodination of erythrocyte components by a myeloperoxidase- mediated system

Blood ◽  
1975 ◽  
Vol 45 (5) ◽  
pp. 699-707
Author(s):  
SJ Klebanoff ◽  
RA Clark
Keyword(s):  
Superoxide Dismutase ◽  
Thyroid Hormones ◽  
Glucose Oxidase ◽  
Xanthine Oxidase ◽  
Combined Effect ◽  
Oxidase System ◽  
Generating System

Erythrocytes are hemolyzed by myeloperoxidase, an H2O2-generating system (glucose + glucose oxidase; hypoxanthine + xanthine oxidase) and an oxidizable cofactor (chloride, iodide, thyroxine, triiodothyronine). The combined effect of chloride and either iodide or the thyroid hormones is greater than additive. Myeloperoxidase can be replaced by lactoperoxidase in the iodide-, thyroxine and triiodothyronine- dependent, but not in the chloride-dependent, systems. Hemolysis is is inhibited by the peroxidase inhibitors, azide and cyanide, and by catalase and is stimulated by superoxide dismutase when the xanthine oxidase system is employed as the source of H2O2. Hemolysis by the iodide-dependent system is associated with the iodination of erythrocyte components.

scholarly journals Synthesis of Sol-Gel Matrices for Encapsulation of Enzymes Using an Aqueous Route

1998 ◽  
Vol 519 ◽  
Author(s):  
R.B. Bhatia ◽  
C.J. Brinker ◽  
C.S. Ashley ◽  
T.M. Harris
Keyword(s):  
Hydrogen Peroxide ◽  
Glucose Oxidase ◽  
Sol Gel ◽  
Enzymatic Reactions ◽  
Host Materials ◽  
Colored Product ◽  
Silicate Matrices ◽  
Kinetics Of ◽  
Oxidation Of Glucose ◽  
Biosensor Applications

AbstractSol-gel matrices are promising host materials for potential chemical and biosensor applications. Previous studies have focused on modified sol-gel routes using alkoxides for encapsulation of enzymes. However the formation of alcohol as a byproduct during hydrolysis and condensation reactions poses limitations. We report the immobilization of glucose oxidase and peroxidase in silica prepared by an aqueous route which may provide a more favorable environment for the biomolecules. A two step aqueous sol-gel procedure using sodium silicate as the precursor was developed to encapsulate the enzymes and the dye precursor, o-dianisidine. Glucose oxidase catalyzes the oxidation of glucose to give gluconic acid and hydrogen peroxide. Peroxidase then catalyzes the reaction of the dye precursor with hydrogen peroxide to produce a colored product. The kinetics of the coupled enzymatic reactions were monitored by optical spectroscopy and compared to those occurring in tetramethyl orthosilicate (TMOS) derived silica matrices developed by Yamanaka et al. [1]. Enhanced kinetics in the aqueous silicate matrices were related to differences in the host microstructures as elucidated by microstructural comparisons of the corresponding aerogels.

Nature of the oxygen species generated by xanthine oxidase involved in secretory histamine release from mast cells

1989 ◽  
Vol 67 (8) ◽  
pp. 397-403 ◽  
Author(s):  
I. Aravind Menon ◽  
Shaila Shirwadkar ◽  
Narendranath S. Ranadive
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Mast Cells ◽  
Xanthine Oxidase ◽  
Cell Lysis ◽  
Oxygen Species ◽  
Hydrogen Peroxide Production ◽  
Oxidase System ◽  
Beneficial Effects ◽  
Cellular Components

The present studies were carried out to characterize the nature of reactive oxygen species generated by the xanthine – xanthine oxidase system involved in the release of histamine by noncytotoxic and cytotoxic mechanisms. To distinguish secretory release from lytic release, mast cells were loaded with 51Cr and the release of 51Cr into the incubation medium was used as a measure of cell lysis. The secretory release of histamine was not inhibited by superoxide dismutase or catalase alone. However, together these agents inhibited the release. This suggests that the combination of superoxide and hydrogen peroxide can evoke secretory release. The lytic release of histamine, as monitored by concomitant release of 51Cr from mast cells at higher concentration of xanthine oxidase or longer periods of incubation, seems to be related to hydrogen peroxide production since catalase inhibited the cell lysis. Since it has been reported that exogenously added hydrogen peroxide at concentrations below 10 mM did not induce cell lysis, the lytic release, although hydrogen peroxide dependent, may not be due to its direct effect on the cell surface. The cell lysis observed in the xanthine – xanthine oxidase system seems to be brought about by a complex mechanism involving the interactions of hydrogen peroxide and superoxide with cellular components. These studies indicate that the beneficial effects of superoxide dismutase seen in biological systems may partly be due to inhibition of the secretory processes stimulated by superoxide.Key words: superoxide, hydrogen peroxide, mast cells, histamine, xanthine oxidase.

Effects of oxygen radicals on cerebral arterioles

1985 ◽  
Vol 248 (2) ◽  
pp. H157-H162 ◽  
Author(s):  
E. P. Wei ◽  
C. W. Christman ◽  
H. A. Kontos ◽  
J. T. Povlishock
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Xanthine Oxidase ◽  
Superoxide Anion ◽  
Anion Radical ◽  
Superoxide Anion Radical ◽  
Residual Effects ◽  
Functional Changes ◽  
Free Hydroxyl ◽  
Cerebral Arterioles

Xanthine oxidase and xanthine, a combination that produces hydrogen peroxide and superoxide anion radical, applied topically in anesthetized cats equipped with cranial windows caused arteriolar dilation during application, sustained dilation 1 h after washout, and reduced reactivity to the vasoconstrictive effects of arterial hypocapnia, discrete lesions of the endothelium, and morphological abnormalities of the vascular smooth muscle by electron microscopy. Similar effects were seen in small, but not in large, arterioles during topical application of hydrogen peroxide or hydrogen peroxide plus ferrous sulfate, a combination that produces free hydroxyl radical. The functional changes caused by xanthine oxidase plus xanthine were inhibited completely by superoxide dismutase plus catalase. Superoxide dismutase or catalase, each by itself, eliminated the residual effects seen after washout and reduced the dilation during application of xanthine oxidase. The results show that superoxide anion radical and hydrogen peroxide produce reversible arteriolar dilation and that consistent vascular damage is produced in the presence of both superoxide anion radical and hydrogen peroxide.

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.

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