Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.6.3.1 (NADPH oxidase)
11,281 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of hydrocortisone on the respiratory burst oxidase (NADPH oxidase, EC 1.6.99.6) from human neutrophils in both whole-cell and full soluble (cell-free) systems were investigated. In the whole-cell system, hydrocortisone inhibited the generation of superoxide by neutrophils exposed to phorbol myristate acetate, suggesting that steroids inhibit the bactericidal capacity of the body in an acute inflammatory phase. Hydrocortisone, which was added to the cuvette after the addition of NADPH and before the addition of sodium dodecyl sulfate, in a cell-free system, was found to inhibit the activation of superoxide-generating NADPH oxidase by sodium dodecyl sulfate. The concentration of hydrocortisone required for 50% inhibition of oxidase was 40 microM. Its inhibition was dose- and time-dependent in the cell-free system. However, hydrocortisone did not alter the Km of the oxidase for NADPH. These results suggest that steroids inhibit the reconstitution of NADPH oxidase by sodium dodecyl sulfate in the cell-free system, and that they do not alter the affinity to NADPH of the oxidase.
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PMID:Hydrocortisone inhibits the respiratory burst oxidase from human neutrophils in whole-cell and cell-free systems. 215 98

Human fibroblasts in primary culture released reactive oxygen species upon exposure to synovial fluid obtained by joint aspiration from twelve patients suffering from rheumatoid arthritis. The primary radical produced was O2- as determined by ESR spin trapping and cytochrome c reduction. In contrast to the oxidative burst in granulocytes and monocytes, radical formation proceeded continuously for at least four hours. Low-level chemiluminescence was increased upon exposure to inflammatory human synovial fluids. Spectral characteristics and effects of azide and 1,4-diazabicyclo-(2,2,2)-octane led to the conclusion that the photoemissive species were excited carbonyls. Radical production and light emission were not altered either by xanthine or allopurinol, nor by azide, cyanide or rotenone. The O2- production increased in the presence of NADH or NADPH, making an NAD(P)H oxidase a likely source. The liberation of reactive oxygen species correlated with the number of leukocytes present in the inflammatory joint fluids, but not with the concentrations of immunoglobulins and complement factor C3.
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PMID:Human fibroblasts release reactive oxygen species in response to treatment with synovial fluids from patients suffering from arthritis. 215 76

Intact neutrophils possess a cellular mechanism that efficiently deactivates the microbicidal O2-generating NADPH oxidase during the respiratory burst (Akard, L. P., English, D., and Gabig, T. G. (1988) Blood 72, 322-327). The present studies directed at identifying the molecular mechanism(s) involved in NADPH oxidase deactivation showed that a heat- and trypsin-insensitive species in the cytosolic fraction from normal unstimulated neutrophils was capable of deactivating the membrane-associated NADPH oxidase isolated from opsonized zymosan- or phorbol 12-myristate 13-acetate-stimulated neutrophils. This cytosolic species also deactivated the cell-free-activated oxidase. Deactivation by this cytosolic species occurred in the absence of NADPH-dependent catalytic turnover and was reversible, since NADPH oxidase activity could be subsequently reactivated in the cell-free system. The sedimentable particulate fraction from unstimulated neutrophils did not demonstrate deactivator activity. Deactivator activity was demonstrated in the neutral lipid fraction of neutrophil cytosol extracted with chloroform:methanol. Following complete purification of cytosolic deactivator activity by thin layer chromatography and reversed phase high performance liquid chromatography, the deactivator species was shown to be a lipid thiobis ester compound by mass spectroscopy. Cellular metabolism of this compound in human neutrophils may reveal a unique mechanism for enzymatic control of the NADPH oxidase system and thereby play an important role in regulation of the inflammatory response.
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PMID:Purification and characterization of a lipid thiobis ester from human neutrophil cytosol that reversibly deactivates the O2- -generating NADPH oxidase. 216 Apr 58

The superoxide (O2-)-generating NADPH oxidase of resting macrophages can be activated in a soluble cell-free system by certain anionic amphiphiles, such as sodium dodecyl sulfate (SDS). We demonstrate that cell-free activation is specifically enhanced by nonhydrolyzable guanosine 5'-triphosphate (GTP) analogues. Guanosine 5'-diphosphate (GDP) and guanosine 5'-O-(2-thiodiphosphate) (GDP beta S) prevent cell-free oxidase activation and reverse the activated state when added to preactivated oxidase preparations. Nonhydrolyzable GTP analogues have a protective effect on the SDS-stimulated NADPH oxidase, as shown by the maintenance of more than 90% and close to 60% of enzyme activity 6 and 24 hr, respectively, after the addition of SDS to the cell-free preparation. A novel procedure is described for separating the activated NADPH oxidase from SDS and added nucleotides by gel filtration of the SDS-stimulated solubilized membrane-cytosol mixtures through a Sephadex G-25 column. By utilizing this method, it was found that the presence of micromolar concentrations of nonhydrolyzable GTP analogues during activation by SDS results in a marked increase in the recovery of SDS-independent, NADPH-dependent O2(-)-producing activity in the excluded volume of the column. It is suggested that GTP stabilizes the SDS-induced complex between membrane and cytosolic components of the oxidase. Cell-free activation of NADPH oxidase by SDS was found to be cholera and pertussis toxin insensitive. These results serve as evidence of the participation of a G protein in the activation of the O2(-)-generating NADPH oxidase of macrophages by SDS.
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PMID:Activation of the superoxide-generating NADPH oxidase of macrophages by sodium dodecyl sulfate in a soluble cell-free system: evidence for involvement of a G protein. 216 54

The effects of non-steroidal anti-inflammatory drugs (NSAIDs) on the respiratory burst oxidase (NADPH oxidase, EC 1.6.99.6) from human neutrophils in both whole cell and fully soluble (cell-free) systems were investigated. Three NSAIDs, indomethacin, salicylic acid and acetylsalicylic acid (aspirin), were found to inhibit the superoxide generation by human neutrophils exposed to phorbol myristate acetate in a whole cell system and the activation of superoxide-generating NADPH oxidase by sodium dodecyl sulfate in a cell-free system. Concentrations of these NSAIDs required for 50% inhibition of the oxidase (IC50) were: indomethacin (180 microM in both systems), salicylic acid (1.30 mM in the cell-free system, and more than 3.0 mM in the whole cell system) and acetylsalicylic acid (1.35 mM in the cell-free system, and more than 3.0 mM in the whole cell system). In addition, in the cell-free system, these NSAIDs did not change the Km values for NADPH of the oxidase. These results suggest that these NSAIDs, especially indomethacin, concentration-dependently inhibit the reconstitution of the solubilized membrane-bound enzyme by sodium dodecyl sulfate in the cell-free system.
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PMID:Effects of non-steroidal anti-inflammatory drugs on human neutrophil NADPH oxidase in both whole cell and cell-free systems. 216 17

Neutrophils (PMN) from newborn calves generate significantly less superoxide anion (O2-) than do their adult counterparts after stimulation with direct protein kinase C agonists. To better understand this observation, we compared the activity and kinetics of NADPH oxidase in membrane fractions from phorbol 12-myristate 13-acetate-stimulated adult and newborn PMN. After phorbol 12-myristate 13-acetate stimulation, PMN were sonicated and the membranes assayed for O2- production with increasing concentrations of NADPH. O2- production was calculated 1 and 2 min after the beginning of the reaction. At all concentrations of NADPH used, there was no difference (p greater than 0.05) in O2- production between adult (n = 8) and newborn (n = 9) PMN membrane preparations. Enzyme kinetics calculations revealed no differences (p greater than 0.05) between age groups in Km and Vmax or in the velocity of the reactions. Determination of the protein content in the membrane pellet, however, showed that adult PMN yielded significantly (p less than 0.01) higher amounts of protein (2.82 +/- 0.14 mg/mL) than did newborn PMN (1.78 +/- 0.07 mg/mL). This difference could be partly attributed to cell size; flow cytometric analysis showed that newborn PMN had a significantly (p less than 0.01) smaller diameter (10.94 +/- 0.07 microns) than did adult PMN (11.65 +/- 0.06 microns), and calculated cell volume and surface area were also both significantly less (p less than 0.01) in newborn PMN.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Membrane NADPH oxidase activity and cell size in bovine neonatal and adult neutrophils. 217

Superoxide (.O2-) production by the NADPH oxidase of a membrane fraction derived from rabbit peritoneal neutrophils activated by 4 beta-phorbol 12-myristate 13-acetate (PMA) was studied at 25 degrees C under different conditions, and measured by the superoxide dismutase inhibitable reduction of cytochrome c. Whereas PMA-activated rabbit neutrophils incubated in a glucose-supplemented medium exhibited a substantial rate of production of .O2-, the membranes prepared by sonication of the activated neutrophils were virtually unable to generate .O2- in the presence of NADPH. Instead, they exhibited an NADPH-dependent diaphorase activity, measured by the superoxide-dismutase-insensitive reduction of cytochrome c. Upon addition of arachidonic acid, which is known to elicit oxidase activation, the NADPH diaphorase activity of the rabbit neutrophil membranes vanished and was stoichiometrically replaced by an NADPH oxidase activity. The emerging oxidase activity was fully sensitive to iodonium biphenyl, a potent inhibitor of the respiratory burst, whereas the diaphorase activity was not affected. Addition of 0.1% Triton X-100 or an excess of arachidonic acid, acting as detergent, resulted in the reappearance of the diaphorase activity at the expense of the oxidase activity. These results indicate that the diaphorase-oxidase transition is reversible. When the rabbit neutrophil membranes were supplemented with rabbit neutrophil cytosol, guanosine 5'-[gamma-thio]triphosphate and Mg2+, in addition to arachidonic acid, not only the NADPH diaphorase activity disappeared, but the emerging NADPH oxidase activity was markedly enhanced (about 10 times compared to that of membranes treated with arachidonic acid alone). The diaphorase-oxidase transition was accompanied by a 10-fold increase in the Km for NADPH, suggesting a change of conformation propagated to the NADPH-binding site during the transition. The treatment of PMA-activated rabbit neutrophils with cross-linking reagents, like glutaraldehyde or 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide, prevented the loss of the PMA-elicited oxidase activity upon disruption of the cells by sonication, suggesting that the interactions between the components of the oxidase complex are stabilized by cross-linking.
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PMID:Respiratory burst of rabbit peritoneal neutrophils. Transition from an NADPH diaphorase activity to an .O2(-)-generating oxidase activity. 217 79

Neutrophil NADPH:O2 oxidoreductase activity, essential in the killing of bacteria by neutrophils, can be elicited in a cell-free system that requires plasma membranes, cytosol and sodium dodecyl sulfate. In addition, GTP or its nonhydrolyzable analog guanosine 5'-3-O-(thio)triphosphate (GTP gamma S) enhances NADPH oxidase activity. We investigated the mechanism of this effect of GTP gamma S in the cell-free system. Cytosol from human neutrophils was separated in three different soluble oxidase components (SOC I, SOC II, and SOC III). Previously we (Bolscher, B. G. J. M., Van Zwieten, R., Kramer, I. J. M., Weening, R. S., Verhoeven, A. J., and Roos, D. (1989) J. Clin. Invest. 83, 757-763) reported that the cytosol contains two components which act synergistically. We now report that one component (previously labeled SOC II) contains two different components that can be separated by ion exchange chromatography. Immunoblotting with antiserum B-1 (Volpp, B. D., Nauseef, W. M., and Clark, R. A. (1988) Science 242, 1295-1297), directed against a cytosolic complex capable of activating latent membranes in the cell-free system, showed a 47-kDa protein in SOC II and a 67-kDa protein in SOC III. SOC II also contains the 47-kDa phosphoprotein, which indicates that this phosphoprotein and the protein recognized by the antiserum are identical. Low rates of NADPH-dependent O2 consumption can be elicited by SOC II and SOC III in the absence of SOC I. This activity is independent of GTP gamma S. Addition of SOC I increases this activity 3-4-fold, only when GTP gamma S is present. Plasma membranes, incubated with SOC I plus GTP gamma S and re-isolated, showed a similar 3-4-fold enhanced O2 consumption with SOC II and SOC III. The GTP gamma S effect is exerted primarily at the level of the plasma membrane. The concentration of GTP gamma S that causes a half-maximal stimulation was 0.4 mu M. It is concluded that SOC I is a functional component of the NADPH oxidase.
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PMID:The activity of one soluble component of the cell-free NADPH:O2 oxidoreductase of human neutrophils depends on guanosine 5'-O-(3-thio)triphosphate. 220 87

The effects of anti-inflammatory drugs (acetylsalicylic acid, ASA; salicylic acid, SA; indomethacin, IM; hydrocortisone, HC) on the respiratory burst oxidase (NADPH oxidase) from human neutrophils in both whole cell and fully soluble (cell-free) systems were investigated. These drugs were found to inhibit the superoxide generation by human neutrophils exposed to phorbol myristate acetate in a whole cell system and the activation of superoxide-generating NADPH oxidase by sodium dodecyl sulfate in cell-free systems. Concentrations of these drugs required for 50% inhibition of the oxidase (ID50) were; ASA (more than 3.0 mM in the whole cell system and 1.35 mM in the cell-free system), SA (more than 3.0 mM in the whole cell system and 1.30 mM in the cell-free system), IM (180 microM in both systems) and HC (50 microM in the whole cell system and 40 microM in the cell-free system). In addition, these drugs time-dependently inhibited the activation of NADPH oxidase in cell-free systems. In the cell-free system, all of the drugs did not change the Km values for NADPH of the oxidase. These results suggest that these anti-inflammatory drugs, especially HC and IM, inhibit the reconstitution (activation) of neutrophil NADPH oxidase enzyme in the cell-free (whole cell) system.
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PMID:[Studies on relationships between the inhibition of human neutrophil NADPH oxidase by anti-inflammatory drugs and development of bacterial infections]. 224 89

The bovine filarial parasite, Setaria cervi, has been found to contain NAD(P)H oxidase activity. The system was predominantly located in the mitochondrial membranes, with very little activity available in the soluble fraction of the organelle. The membrane preparation also exhibited the presence of a reduced pyridine nucleotide transhydrogenase which converted NADPH into NADH by transferring a hydride ion. The oxidase activity was inhibited by all the respiratory inhibitors examined, with the greatest sensitivity to rotenone, a site I-specific inhibitor. The system was also found to be susceptible to exposure to anthelmintics, amongst which levamisole proved the most effective.
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PMID:Mitochondrial NADH oxidase activity of Setaria cervi. 226 25


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