Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.8.1.4 (diaphorase)
 2,754 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fifteen isolates of Verticillium dahliae (eight of race 1, seven of race 2; most from the island of Crete, Greece) were examined for isozyme and molecular variation. Among the isozyme banding patterns (zymograms) of six enzymes that were "activity-stained" after electrophoresis in 9% polyacrylamide gels, differences were observed in diaphorase, alpha-esterase, peroxidase and superoxide dismutase; 2, 2, 3 and 5 different types of zymograms were recorded, respectively. The zymograms could not be correlated with either race 1 or 2. However, all six isolates originating from the Oropedio (plateau) area of Lasithi (Crete) showed an esterase zymogram clearly distinguishable from the other isolates. No differences were observed when staining for acid phosphatase or aspartate aminotransferase ('glutamic-oxaloacetic transaminase'). Furthermore, electrophoresis of random-amplified polymorphic DNA (RAPD) in 2% agarose gels showed that three race-2 isolates from Oropedio of Lasithi could also be distinguished by the RAPD pattern generated with primer OPA-1. The variation observed possibly represents adaptation of V. dahliae to the Oropedio environment.
 ...
PMID:Isozyme variation in Verticillium dahliae isolates from Crete. 1205 96

Peroxidase/H2O2/phenothiazine systems irreversibly inhibit Trypanosoma cruzi dihydrolipoamide dehydrogenase (LADH). Inactivation of the parasite enzyme depended on (a) phenothiazine structure; (b) peroxidase nature; (c) incubation time and (d) the presence of a cation radical scavenger. With the myeloperoxidase/H2O2/system, promazine, trimeprazine, thioridazine, promethiazine, prochlorperazine, chlorpromazine and perphenazine were the most effective derivatives out of twelve phenothiazines studied. An electronegative substituent at position 2 of the phenothiazine ring such as Cl, or trifluoromethyl, propionyl and nitrile groups decreased or nullified phenothiazine activity. Myeloperoxidase/H2O2/, horseradish peroxidase/H2O2/, and myoglobin/H2O2/systems activated phenothiazines producing the corresponding cation radicals, myeloperoxidase being the most selective one with respect to phenothiazine structure. The myoglobin/H2O2/system activated phenothiazines that were scarcely active or inactivate with the MPO/H2O2/system, such as the trifluoromethyl derivatives. Production of phenothiazine cation radicals was demonstrated by optical spectroscopy. Phenothiazine cation radical stability depended on their structure as illustrated by promazine and thioridazine. Thiol compounds (GSH, N-acetyl-cysteine and penicillamine), aromatic aminoacids (L-tyrosine, L-tryptophan, and the corresponding peptides) and ascorbate scavenged phenothiazine cation radicals, thus preventing LADH inactivation. Comparison of the summarized phenothiazine effects with those of phenothiazines on T. cruzi suggest the role of cation radicals in phenothiazines chemotherapeutic actions.
 ...
PMID:Myeloperoxidase-generated phenothiazine cation radicals inactivate Trypanosoma cruzi dihydrolipoamide dehydrogenase. 1218 Feb 62

Phenothiazine cation radicals (PTZ+*) irreversibly inactivated Trypanosoma cruzi dihydrolipoamide dehydrogenase (LADH). These radicals were obtained by phenothiazine (PTZ) peroxidation with myeloperoxidase (MPO) or horseradish peroxidase (HRP/H2O2) systems. LADH inactivation depended on PTZ structure and incubation time. After 10 min incubation of LADH with the MPO-dependent systems, promazine, trimeprazine and thioridazine were the most effective; after 30 min incubation, chlorpromazine, prochlorperazine and promethazine were similarly effective. HRP-dependent systems were equally or more effective than the corresponding MPO-dependent ones. Chloro, trifluoro, propionyl and nitrile groups at position 2 of the PTZ ring significantly decreased molecular activity, specially with the MPO/H2O2 systems. Comparison of inactivation values for LADH and T. cruzi trypanothione reductase demonstrated a greater sensitivity of LADH to chlorpromazine and perphenazine and a 10-fold lower sensitivity to promazine, thioridazine and trimeprazine. Alkylamino, alkyl-piperidinyl or alkyl-piperazinyl groups at position 10 modulated PTZ activity to a limited degree. Production of PTZ+* radicals was demonstrated by optical and ESR spectroscopy methods. PTZ+* radicals stability depended on their structure as demonstrated by promazine and thioridazine radicals. Thiol compounds such as GSH and N-acetylcysteine, L-tyrosine, L-tryptophan, the corresponding peptides, ascorbate and Trolox, prevented LADH inactivation by the MPO/H2O2/thioridazine system, in close agreement with their action as PTZ+* scavengers. NADH (not NAD+) produced transient protection of LADH against thioridazine and promazine radicals, the protection kinetics being affected by the relatively fast rate of NADH oxidation by these radicals. The role of the observed effects of PTZ radicals for PTZ cytotoxicity is discussed.
 ...
PMID:Phenothiazine radicals inactivate Trypanosoma cruzi dihydrolipoamide dehydrogenase: enzyme protection by radical scavengers. 1268 23

Mycobacterium tuberculosis (Mtb) persists for prolonged periods in macrophages, where it must adapt to metabolic limitations and oxidative/nitrosative stress. However, little is known about Mtb's intermediary metabolism or antioxidant defences. We recently identified a peroxynitrite reductase-peroxidase complex in Mtb that included products of the genes sucB and lpd, which are annotated to encode the dihydrolipoamide succinyltransferase (E2) and lipoamide dehydrogenase (E3) components of alpha-ketoglutarate dehydrogenase (KDH). However, we could detect no KDH activity in Mtb lysates, nor could we reconstitute KDH by combining the recombinant proteins SucA (annotated as the E1 component of KDH), SucB and Lpd. We therefore renamed the sucB product dihydrolipoamide acyltransferase (DlaT). Mtb lysates contained pyruvate dehydrogenase (PDH) activity, which was lost when the dlaT gene (formerly, sucB) was disrupted. Purification of PDH from Mtb yielded AceE, annotated as an E1 component of PDH, along with DlaT and Lpd. Moreover, anti-DlaT antibody coimmunoprecipitated AceE. Finally, recombinant AceE, DlaT and Lpd, although encoded by genes that are widely separated on the chromosome, reconstituted PDH in vitro with Km values typical of bacterial PDH complexes. In sum, Mtb appears to lack KDH. Instead, DlaT and Lpd join with AceE to constitute PDH.
 ...
PMID:Mycobacterium tuberculosis appears to lack alpha-ketoglutarate dehydrogenase and encodes pyruvate dehydrogenase in widely separated genes. 1604 27

We report the 2.4 A crystal structure for lipoamide dehydrogenase encoded by lpdC from Mycobacterium tuberculosis. Based on the Lpd structure and sequence alignment between bacterial and eukaryotic Lpd sequences, we generated single point mutations in Lpd and assayed the resulting proteins for their ability to catalyze lipoamide reduction/oxidation alone and in complex with other proteins that participate in pyruvate dehydrogenase and peroxidase activities. The results suggest that amino acid residues conserved in mycobacterial species but not conserved in eukaryotic Lpd family members modulate either or both activities and include Arg-93, His-98, Lys-103, and His-386. In addition, Arg-93 and His-386 are involved in forming both "open" and "closed" active site conformations, suggesting that these residues play a role in dynamically regulating Lpd function. Taken together, these data suggest protein surfaces that should be considered while developing strategies for inhibiting this enzyme.
 ...
PMID:Crystal structure and functional analysis of lipoamide dehydrogenase from Mycobacterium tuberculosis. 1609 39

In the current work we investigated for the first time the biochemical basis of 4-hydroxyanisole (4-HA) induced toxicity in B16-F0 melanoma cells. It was found that dicoumarol, a diaphorase inhibitor, and 1-bromoheptane, a GSH depleting agent, increased 4-HA induced toxicity towards B16-F0 cells whereas dithiothreitol, a thiol containing agent, and ascorbic acid (AA), a reducing agent, largely prevented 4-HA toxicity. TEMPOL and pyrogallol, free radical scavengers, did not significantly prevent 4-HA toxicity towards B16-F0 cells. GSH>AA>NADH prevented the o-quinone formation when 4-HA was metabolized by tyrosinase/O(2). 4-HA metabolism by horseradish peroxidase/H(2)O(2) was prevented more effectively by AA than NADH>GSH. We therefore concluded that quinone formation was the major pathway for 4-HA induced toxicity in B16-F0 melanoma cells whereas free radical formation played a negligible role in the 4-HA induced toxicity.
 ...
PMID:Biochemical basis of 4-hydroxyanisole induced cell toxicity towards B16-F0 melanoma cells. 1642 88

Ferric leghemoglobin reductase (FLbR) from soybean (Glycine max [L.] Merr) nodules catalyzed oxidation of NADH, reduction of ferric leghemoglobin (Lb(+3)), and reduction of dichloroindophenol (diaphorase activity). None of these reactions was detectable when O(2) was removed from the reaction system, but all were restored upon readdition of O(2). In the absence of exogenous electron carriers and in the presence of O(2) and excess NADH, FLbR catalyzed NADH oxidation with the generation of H(2)O(2) functioning as an NADH oxidase. The possible involvement of peroxide-like intermediates in the FLbR-catalyzed reactions was analyzed by measuring the effects of peroxidase and catalase on FLbR activities; both enzymes at low concentrations (about 2 mug/mL) stimulated the FLbR-catalyzed NADH oxidation and Lb(+3) reduction. The formation of H(2)O(2) during the FLbR-catalyzed NADH oxidation was confirmed using a sensitive assay based on the fluorescence emitted by dichlorofluorescin upon reaction with H(2)O(2). The stoichiometry ratios between the FLbR-catalyzed NADH oxidation and Lb(+3) reduction were not constant but changed with time and with concentrations of NADH and O(2) in the reaction solution, indicating that the reactions were not directly coupled and electrons from NADH oxidation were transferred to Lb(+3) by reaction intermediates. A study of the affinity of FLbR for O(2) showed that the enzyme required at least micromolar levels of dissolved O(2) for optimal activities. A mechanism for the FLbR-catalyzed reactions is proposed by analogy with related oxidoreductase systems.
 ...
PMID:Involvement of Molecular Oxygen in the Enzyme-Catalyzed NADH Oxidation and Ferric Leghemoglobin Reduction. 1665 65

Neocortical gamma-aminobutyric acid (GABA)ergic neurons have been previously described as largely involved in local intracortical circuitry. However, our recent findings in the murine model described select neocortical GABAergic neurons that project to both neighboring and more distant neocortical regions. Here, we investigated whether such GABAergic projection neurons are also found in the cat neocortex. Wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) was injected into the visual, auditory, or somatosensory cortex, in order to label efferent cortical neurons retrogradely and to label axons and terminals orthogradely. Staining for nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d), an enzyme involved in nitric oxide synthesis, was employed, and co-localization with WGA-HRP was determined by means of both polarizing and brightfield microscopy. We concluded that neurons double-labeled with WGA-HRP and NADPH-d in a distant region from the WGA-HRP-injection site are GABAergic neurons with long-range projection axons. All double-labeled neurons were found in cortical layers VIa and VIb and in the white matter. Neurons with intense NADPH-d reactivity (type I) were determined to be neuronal nitric oxide synthase (nNOS) positive in all cases. However, weakly NADPH-d-reactive neurons (type II) lacked nNOS immunoreactivity. Moreover, nNOS often co-localized with GABA, neuropeptide-Y, and somatostatin in the cat neocortex. In summary, the GABAergic neurons described here projected in a manner similar to that previously described for neocortical principal neurons, although some unique GABAergic long-range projections were also demonstrated.
 ...
PMID:Long-range GABAergic projection neurons in the cat neocortex. 1750 78

Covalent modifications of proteins by endogenous reactive nitrogen oxide species lead to cytotoxic effects that are implicated in diseases associated with chronic infections and inflammation. Tyrosine nitration is a major post-translational modification of proteins by reactive nitrogen oxide species. Recent studies suggest that nitrotyrosine is not a permanent protein modification. We previously demonstrated that lipoyl dehydrogenase is capable of converting 3-nitrotyrosine into 3-aminotyrosine in the presence of certain reducing agents. In this study, we compared the abilities of various hemoproteins, hemin, and the cobalt-containing cofactor cyanocobalamin to mediate H(2)O(2)/nitrite-dependent tyrosine nitration and found that these hemoproteins and metal-containing cofactors also catalyzed the reduction of 3-nitrotyrosine to various extents in the presence of thiol reducing agents or ascorbate. The H(2)O(2)/nitrite-induced post-translational modifications of human hemoglobin identified by nanoLC/nanospray ionization tandem mass spectrometric analysis of the tryptic digest include nitration of tyrosine and tryptophan, as well as oxidation of methionine and cysteine residues. Nitration of human hemoglobin by H(2)O(2)/nitrite was detected on Tyr24 and Tyr42 (alpha-chain) and on Tyr130 and Trp15 (beta-chain) in the alphabeta-dimer. Oxidation of methionine and cysteine residues was also observed. Furthermore, hemoglobin also catalyzed nitro reduction of 3-nitrotyrosine to form 3-aminotyrosine, at Tyr24 in the alpha-chain peptide of human Hb in the presence of ascorbate. The enhanced peroxidase activity of nitrated hemoglobin can be reversed by the antioxidant ascorbate. These results suggest a possible in vivo pathway for hemoglobin contributing to denitration of nitrated proteins through redox regulation.
 ...
PMID:H2O2/nitrite-induced post-translational modifications of human hemoglobin determined by mass spectrometry: redox regulation of tyrosine nitration and 3-nitrotyrosine reduction by antioxidants. 1816 31

The construction and performance of integrated amperometric biosensors for the determination of glycerol are reported. Two different biosensor configurations have been evaluated: one based on the glycerol dehydrogenase/diaphorase (GDH/DP) bienzyme system, and another using glycerol kinase/glycerol-3-phosphate oxidase/peroxidase (GK/GPOx/HRP). Both enzyme systems were immobilized together with the mediator tetrathiafulvalene (TTF) on a 3-mercaptopropionic acid (MPA) self-assembled monolayer (SAM)-modified gold electrode by using a dialysis membrane. The electrochemical oxidation of TTF at +150mV (vs. Ag/AgCl), and the reduction of TTF(+) at 0mV were used for the monitoring of the enzyme reactions for the bienzyme and trienzyme configurations, respectively. Experimental variables concerning both the biosensors composition and the working conditions were optimized for each configuration. A good repeatability of the measurements with no need of cleaning or pretreatment of the biosensors was obtained in both cases. After 51 days of use, the GDH/DP biosensor still exhibited 87% of the original sensitivity, while the GK/GPOx/HRP biosensor yielded a 46% of the original response after 8 days. Calibration graphs for glycerol with linear ranges of 1.0x10(-6) to 2.0x10(-5) or 1.0x10(-6) to 1.0x10(-5)M glycerol and sensitivities of 1214+/-21 or 1460+/-34microAM(-1) were obtained with GDH/DP and GK/GPOx/HRP biosensors, respectively. The calculated detection limits were 4.0x10(-7) and 3.1x10(-7)M, respectively. The biosensors exhibited a great sensitivity with no significant interferences in the analysis of wines. The biosensors were applied to the determination of glycerol in 12 different wines and the results advantageously compared with those provided by a commercial enzyme kit.
 ...
PMID:Integrated multienzyme electrochemical biosensors for the determination of glycerol in wines. 1826 15


<< Previous 1 2 3 4 5 6 Next >>