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)

Hydrogen peroxide is the final electron acceptor for the biosynthesis of thyroid hormone catalyzed by thyroperoxidase at the apical surface of thyrocytes. Pig and human thyroid plasma membrane contain a Ca(2+)-dependent NAD(P)H oxidase that generates H(2)O(2) by transferring electrons from NAD(P)H to molecular oxygen. We purified from pig thyroid plasma membrane a flavoprotein which constitutes the main, if not the sole, component of the thyroid NAD(P)H oxidase. Microsequences permitted the cloning of porcine and human full-length cDNAs encoding, respectively, 1207- and 1210-amino acid proteins with a predicted molecular mass of 138 kDa (p138(Tox)). Human and porcine p138(Tox) have 86.7% identity. The strongest similarity was to a predicted polypeptide encoded by a Caenorhabditis cDNA and with rbohA, a protein involved in the Arabidopsis NADPH oxidase. p138(Tox) shows also similarity to the p65(Mox) and to the gp91(Phox) in their C-terminal region and have consensus sequences for FAD- and NADPH-binding sites. Compared with gp91(Phox), p138(Tox) shows an extended N-terminal containing two EF-hand motifs that may account for its calcium-dependent activity, whereas three of four sequences implicated in the interaction of gp91(Phox) with the p47(Phox) cytosolic factor are absent in p138(Tox). The expression of porcine p138(Tox) mRNA analyzed by Northern blot is specific of thyroid tissue and induced by cyclic AMP showing that p138(Tox) is a differentiation marker of thyrocytes. The gene of human p138(Tox) has been localized on chromosome 15q15.
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PMID:Purification of a novel flavoprotein involved in the thyroid NADPH oxidase. Cloning of the porcine and human cdnas. 1060 Dec 91

A NAD(P)H oxidase has been isolated from the archaeon Sulfolobus solfataricus. The enzyme is a homodimer with M(r) 38,000 per subunit (SsNOX38) containing 1 FAD molecule/subunit. It oxidizes NADH and, less efficiently, NADPH with the formation of hydrogen peroxide. The enzyme was resistant against chemical and physical denaturating agents. The temperature for its half-denaturation was 93 and 75 degrees C in the absence or presence, respectively, of 8 M urea. The enzyme did not show any reductase activity. The SsNOX38 encoding gene was cloned and sequenced. It accounted for a product of 36.5 kDa. The translated amino acid sequence was made of 332 residues containing two putative betaalphabeta-fold regions, typical of NAD- and FAD-binding proteins. The primary structure of SsNOX38 did not show any homology with the N-terminal amino acid sequence of a NADH oxidase previously isolated from S. solfataricus (SsNOX35) (Masullo, M., Raimo, G., Dello Russo, A., Bocchini, V. and Bannister, J. V. (1996) Biotechnol. Appl. Biochem. 23, 47-54). Conversely, it showed 40% sequence identity with a putative thioredoxin reductase from Bacillus subtilis, but it did not contain cysteines, which are essential for the activity of the reductase.
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PMID:A NAD(P)H oxidase isolated from the archaeon Sulfolobus solfataricus is not homologous with another NADH oxidase present in the same microorganism. Biochemical characterization of the enzyme and cloning of the encoding gene. 1062 24

Since an increased endothelial superoxide formation plays an important role in the pathogenesis of endothelial dysfunction its specific detection is of particular interest. The widely used superoxide probe lucigenin, however, has been reported to induce superoxide under certain conditions, especially in the presence of NADH. This raises questions as to the conclusion of a NAD(P)H oxidase as the major source of endothelial superoxide. Using independent methods, we showed that lucigenin in the presence of NADH leads to the production of substantial amount of superoxide (approximately 15-fold of control) in endothelial cell homogenates. On the other hand, these independent methods revealed that endothelial cells without lucigenin still produce superoxide in a NAD(P)H-dependent manner. This was blocked by inhibitors of the neutrophil NADPH oxidase diphenyleniodonium and phenylarsine oxide. Our results demonstrate that a NAD(P)H-dependent oxidase is an important source for endothelial superoxide but the latter, however, cannot be measured reliably by lucigenin.
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PMID:Pitfalls of using lucigenin in endothelial cells: implications for NAD(P)H dependent superoxide formation. 1073 Aug 25

Superoxide anion plays important roles in vascular disease states. Increased superoxide production contributes to reduced nitric oxide (NO) bioactivity and endothelial dysfunction in experimental models of vascular disease. We measured superoxide production by NAD(P)H oxidase in human blood vessels and examined the relationships between NAD(P)H oxidase activity, NO-mediated endothelial function, and clinical risk factors for atherosclerosis. Endothelium-dependent vasorelaxations and direct measurements of vascular superoxide production were determined in human saphenous veins obtained from 133 patients with coronary artery disease and identified risk factors. The predominant source of vascular superoxide production was an NAD(P)H-dependent oxidase. Increased vascular NAD(P)H oxidase activity was associated with reduced NO-mediated vasorelaxation. Furthermore, reduced endothelial vasorelaxations and increased vascular NAD(P)H oxidase activity were both associated with increased clinical risk factors for atherosclerosis. Diabetes and hypercholesterolemia were independently associated with increased NADH-dependent superoxide production. The association of increased vascular NAD(P)H oxidase activity with endothelial dysfunction and with clinical risk factors suggests an important role for NAD(P)H oxidase-mediated superoxide production in human atherosclerosis. The full text of this article is available at http://www.circresaha.org. Key Words:atherosclerosis endothelium superoxide nitric oxide diabetes Two Distinct Congenital Arrhythmias Evoked by a Multidysfunctional Na(+) Channel Marieke W. Veldkamp, Prakash C. Viswanathan, Connie Bezzina, Antonius Baartscheer, Arthur A.M. Wilde, Jeffrey R. Balser Abstract-The congenital long-QT syndrome (LQT3) and the Brugada syndrome are distinct, life-threatening rhythm disorders linked to autosomal dominant mutations in SCN5A, the gene encoding the human cardiac Na(+) channel. It is believed that these two syndromes result from opposite molecular effects: LQT3 mutations induce a gain of function, whereas Brugada syndrome mutations reduce Na(+) channel function. Paradoxically, an inherited C-terminal SCN5A mutation causes affected individuals to manifest electrocardiographic features of both syndromes: QT-interval prolongation (LQT3) at slow heart rates and distinctive ST-segment elevations (Brugada syndrome) with exercise. In the present study, we show that the insertion of the amino acid 1795insD has opposite effects on two distinct kinetic components of Na(+) channel gating (fast and slow inactivation) that render unique, simultaneous effects on cardiac excitability. The mutation disrupts fast inactivation, causing sustained Na(+) current throughout the action potential plateau and prolonging cardiac repolarization at slow heart rates. At the same time, 1795insD augments slow inactivation, delaying recovery of Na(+) channel availability between stimuli and reducing the Na(+) current at rapid heart rates. Our findings reveal a novel molecular mechanism for the Brugada syndrome and identify a new dual mechanism whereby single SCN5A mutations may evoke multiple cardiac arrhythmia syndromes by influencing diverse components of Na(+) channel gating function. The full text of this article is available at http://www.circresaha.org. Key Words: Na(+) channel inactivation long-QT syndrome Brugada syndrome
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PMID:UltraRapid communications : vascular superoxide production by NAD(P)H OxidaseAssociation with endothelial dysfunction and clinical risk factors 1080 75

Superoxide anion plays important roles in vascular disease states. Increased superoxide production contributes to reduced nitric oxide (NO) bioactivity and endothelial dysfunction in experimental models of vascular disease. We measured superoxide production by NAD(P)H oxidase in human blood vessels and examined the relationships between NAD(P)H oxidase activity, NO-mediated endothelial function, and clinical risk factors for atherosclerosis. Endothelium-dependent vasorelaxations and direct measurements of vascular superoxide production were determined in human saphenous veins obtained from 133 patients with coronary artery disease and identified risk factors. The predominant source of vascular superoxide production was an NAD(P)H-dependent oxidase. Increased vascular NAD(P)H oxidase activity was associated with reduced NO-mediated vasorelaxation. Furthermore, reduced endothelial vasorelaxations and increased vascular NAD(P)H oxidase activity were both associated with increased clinical risk factors for atherosclerosis. Diabetes and hypercholesterolemia were independently associated with increased NADH-dependent superoxide production. The association of increased vascular NAD(P)H oxidase activity with endothelial dysfunction and with clinical risk factors suggests an important role for NAD(P)H oxidase-mediated superoxide production in human atherosclerosis. The full text of this article is available at http://www.circresaha.org.
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PMID:Vascular superoxide production by NAD(P)H oxidase: association with endothelial dysfunction and clinical risk factors. 1080 76

The production of reactive oxygen species (ROS) by a putative NADPH oxidase-like enzyme system is thought to contribute to antimicrobial activity in oyster hemocytes. NADPH oxidase in vertebrate phagocytes generates superoxide anion from molecular oxygen and NADPH, which is then converted to additional ROS, including H2O2 and HOCl. The fungicide chlorothalonil (TCIN) is a thiol-reactive compound that binds to protein sulfhydryl groups, which can result in enzyme inactivation. NADPH oxidase, containing several sulfhydryl groups, is a potential target of TCIN. Previous studies have demonstrated that in vitro exposure of fish (Morone saxatilus) macrophages to TCIN (10-500 microg/L) suppressed immunostimulated ROS and baseline NAD[P]H concentration but did not inhibit phagocytosis; the production of NADPH in stimulated cells was decreased only at the highest concentration. In this study, we evaluated the effects of TCIN (10-500 microg/L) on oyster hemocyte functions. As with striped bass macrophages, in vitro exposure to TCIN suppressed hemocyte ROS production in a dose-dependent manner, but did not affect phagocytosis. In contrast to the striped bass data, baseline NAD[P]H concentration was relatively unaffected and immunostimulated NAD[P]H production was marginally suppressed at the higher exposure concentrations. Despite these minor differences, these results suggest that TCIN may also be inhibiting an NAD[P]H oxidase-like enzyme in oyster hemocytes.
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PMID:The effects of chlorothalonil on oyster hemocyte activation: phagocytosis, reduced pyridine nucleotides, and reactive oxygen species production. 1084 84

Small, muscular pulmonary arteries (PAs) constrict within seconds of the onset of alveolar hypoxia, diverting blood flow to better-ventilated lobes, thereby matching ventilation to perfusion and optimizing systemic PO2. This hypoxic pulmonary vasoconstriction (HPV) is enhanced by endothelial derived vasoconstrictors, such as endothelin, and inhibited by endothelial derived nitric oxide. However, the essence of the response is intrinsic to PA smooth muscle cells in resistance arteries (PASMCs). HPV is initiated by inhibition of the Kv channels in PASMCs which set the membrane potential (EM). It is currently uncertain whether this reflects an initial inhibitory effect of hypoxia on the K+ channels or an initial release of intracellular Ca2+, which then inhibits K+ channels. In either scenario, the resulting depolarization activates L-type, voltage gated Ca2+ channels, which raises cytosolic calcium levels [Ca2+]i and causes vasoconstriction. Nine families of Kv channels are recognized from cloning studies (Kv1-Kv9), each with subtypes (i.e. Kv1.1-1.6). The contribution of an individual Kv channel to the whole-cell current (IK) is difficult to determine pharmacologically because Kv channel inhibitors are nonspecific. Furthermore, the PASMC's IK is an ensemble, reflecting activity of several channels. The K+ channels which set EM, and inhibition of which initiates HPV, conduct an outward current which is slowly inactivating, and which is blocked by the Kv inhibitor 4-aminopyridine (4-AP) but not by inhibitors of Ca(2+)- or ATP-sensitive K+ channels. Using anti-Kv antibodies to immunolocalize and inhibit Kv channels, we showed that the PASMC contains numerous types of Kv channels from the Kv1 and Kv2 families., Furthermore Kv1.5 and Kv2.1 may be important in determining the EM and play a role as effectors of HPV in PASMCs. While the Kv channels in PASMCs are the "effectors" of HPV, it is uncertain whether they are intrinsically O2-sensitive or are under the control of an "O2 sensor". Certain Kv channels are rich in cysteine, and respond to the local redox environment, tending to open when oxidized and close when reduced. Candidate sensors vary the PASMC redox potential in proportion to O2. These include Nicotinamide Adenine Dinucleotide Phosphate Oxidase, (NADPH oxidase) and the cytosolic ratio of reduced/oxidized redox couples (i.e. glutathione GSH/GSSG), as controlled by electron flux in the mitochondrial electron transport chain (ETC). Using a mouse that lacks the gp91phox component of NADPH oxidase, we have recently shown that loss of the gp91phox-containing NADPH oxidase as a source of activated oxygen species does not impair HPV. However, inhibition of complex 1 of the mitochondrial electron transport chain mimics hypoxia in that it inhibits IK, reduces the production of activated O2 species and causes vasoconstriction. We hypothesize that a redox O2 sensor, perhaps in the mitochondrion, senses O2 through changes in the accumulation of freely diffusible electron donors. Changes in the ratio of reduced/oxidized redox couples, such as NADH/NAD+ and glutathione (GSH/GSSG) can reduce or oxidize the K+ channels, resulting in alterations of PA tone.
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PMID:Molecular identification of O2 sensors and O2-sensitive potassium channels in the pulmonary circulation. 1084 63

Although Rhodococcus spp. strains are able to degrade methoxyphenols by enzymatic means, the contact with veratric acid (3, 4-dimethoxybenzoic acid, hereafter called veratrate) is very stressful for the cells of Rhodococcus erythropolis DSM 1069 (Rh). Within 5 min of contact veratrate in phosphate buffer, the emergence of many vacuoles was observed in the cell body and respiratory bursts, with violent endogenous oxygen uptake, took place several times during the 24 h incubation. During these peaks (where the cells were in their MAX states), increased activity of NADH oxidase was noted, accompanied by maximal accumulation of vanillic and isovanillic acids (3-methoxy-4-hydroxybenzoic acid and 4-hydroxy-3-methoxybenzoic acid respectively, hereafter called vanillates) in the incubation medium, which appeared to be products of veratrate demethylation. At the troughs (cell in their MIN state), the vacuoles disappeared from the cell body, oxygen uptake was normal, and the pool of vanillates decreased while the veratrate level in the medium increased. The cells from MAX and MIN states reacted in opposite ways in the presence of either formaldehyde and GSH, or paraquate and cAMP. The NADH oxidase activity, measured as oxygen uptake against NADH in the membrane pellets of MAX and MIN stage cells, differed in their response to the exogenous presence of FAD, ATP, cAMP, catalase, GSH, H(2)O(2)and methoxyphenolic substrates. The periodic character of these events is described here. Co-operation between two multiprotein membrane complexes (NAD(P)H oxidase and 3-O/4-O-demethylases) in Rhodococcus erythropolis cells and their competition for two common substrates-NAD(P)H and O(2)-is proposed as an explanation for rhythmical nature of these reactions.
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PMID:Multiple respiratory bursts as a response to veratrate stress in Rhodococcus erythropolis cells. 1092 25

The production of reactive oxygen species (ROS) within endothelial cells may have several effects, including alterations in the activity of paracrine factors, gene expression, apoptosis, and cellular injury. Recent studies indicate that a phagocyte-type NAD(P)H oxidase is a major source of endothelial ROS. In contrast to the high-output phagocytic oxidase, the endothelial enzyme has much lower biochemical activity and a different substrate specificity (NADH>NADPH). In the present study, we (1) cloned and characterized the cDNA and predicted amino acid structures of the 2 major subunits of rat coronary microvascular endothelial cell NAD(P)H oxidase, gp91-phox and p22-phox; (2) undertook a detailed comparison with phagocytic NADPH oxidase sequences; and (3) studied the subcellular location of these subunits in endothelial cells. Although these studies revealed an overall high degree of homology (>90%) between the endothelial and phagocytic oxidase subunits, the endothelial gp91-phox sequence has potentially important differences in a putative NADPH-binding domain and in putative glycosylation sites. In addition, the subcellular location of the endothelial gp91-phox and p22-phox subunits is significantly different from that reported for the neutrophil oxidase, in that they are predominantly intracellular and collocated in the vicinity of the endoplasmic reticulum. This first detailed characterization of gp91-phox and p22-phox structure and location in endothelial cells provides new data that may account, in part, for the differences in function between the phagocytic and endothelial NAD(P)H oxidases.
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PMID:Molecular characterization and localization of the NAD(P)H oxidase components gp91-phox and p22-phox in endothelial cells. 1093 10

Intracellular redox levels play an important role in physiology and pathophysiology. The principal intracellular reductant is NADPH, which is required for both the proper activity of the entire antioxidant system and important prooxidant enzymes such as nitric oxide synthase and NADPH oxidase. Thus an easy and accurate measurement of NADPH is very desirable. The method described in this paper is based on the fact that NADH and NADPH (not NAD(+) and NADP(+)) affect absorbance at 340 nm. A single cell extract is separated into three aliquots (A(1), A(2), and A(3)). A(1) is untreated and the absorbance at 340 nm is measured. A(2) is treated with an enzyme that converts all of the NADP(+) to NADPH and then the absorbance at 340 nm is measured. A(3) is treated with an enzyme that converts all of the NADPH to NADP(+) and then the absorbance at 340 nm is measured. A(1) - A(3) is the NADPH content and A(2) - A(1) is the NADP(+) content of the extract. Using this method, we have obtained full recovery of all added nucleotides from cell extracts, thus making the method suitable for the quick determination of NADP(+) and NADPH in living cells. We conclude that this method for the measurement of NADP(+) and NADPH is rapid, simple, accurate, and reliable.
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PMID:A method for determination of pyridine nucleotides using a single extract. 1099 77


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