Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Indophenol”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources
PubMed1980

Menadione reductase from Clostridium tyrobutyricum.

Menadione reductase (EC 1.6.99.2) has been purified 67-fold from Clostridium tyrobutyricum extracts. The molecular weight was found to be 60 000 and the prosthetic group was identified as FMN on the basis of the enzymatic analysis data. The binding of FMN to the menadione dehydrogenase apoenzyme was relatively weak with an apparent Km value of 2.5 x 10(-6) M. The enzyme exhibited group substrate specificity for compounds with a quinoid structure; naphthoquinones and benzoquinones without long carbon chain substituents were the most active. The reactivity of the enzyme with vitamin K1, coenzyme Q6, and cytochrome c was negligible and, with 2,6-dichlorophenol indophenol, relatively low. It was shown that the enzymatic reduction of menadione with the participation of either NADH or NADPH takes place by a "Ping-Pong" mechanism. The enzyme catalyzed the oxidation of NADH and NADPH at equal rates and was inhibited by dicumarol and p-chloromercuribenzoate.

Clostridium↗
PubMed1995

Diversity of lactate metabolism in halophilic archaea.

D-Lactate is readily used as a substrate for the growth of species of halophilic archaea belonging to the genera Haloferax and Haloarcula. L-Lactate was used by Haloferax species (Haloferax volcanii, Haloferax mediterranei) only when a substantial concentration of the D-isomer was also present in the medium. On the enzymatic level, considerable diversity was found in the lactate metabolism of the different representatives of the Halobacteriaceae. At least three types of lactate dehydrogenases were detected in halophilic archaea. A high level of activity of an NAD-linked enzyme was present constitutively in Haloarcula species, and a low level of activity was also detected in Haloferax mediterranei. NAD-independent lactate dehydrogenases, oxidizing L-lactate and D-lactate with 2,6-dichlorophenol-indophenol as electron acceptor, were detected in all nine species tested, but L-lactate dehydrogenase activity in Halobacterium species was very low, and Haloarcula species, which possess a high level of activity of NAD-linked lactate dehydrogenase, showed very low activities of both NAD-independent D- and L-lactate dehydrogenase. An inducible lactate racemase, displaying an unusually high pH optimum, was found in Haloferax volcanii. Lactate racemase activity was found constitutively in Haloarcula species, but no activity was detected in Halobacterium species and in Haloferax mediterranei.

Halobacteriaceae↗
PubMed1994

Properties of a superoxide anion-generating microsomal NADH oxidoreductase, a potential pulmonary artery PO2 sensor.

In this study, we describe properties of a microsomal NADH oxidoreductase that is a potential PO2-dependent source of vasoactive reactive O2 species in the calf pulmonary artery. Microsomes show an NADH-dependent production of superoxide anion (O2-.), as detected by lucigenin-elicited chemiluminescence, a superoxide dismutase inhibited reduction of nitro blue tetrazolium (NBT) and 2,6-dichlorophenol-indophenol, and O2 consumption. The microsomal production of O2-. was modulated by physiologically relevant levels of NADH and PO2, and O2-. production was reduced by inhibitors of NADH-dependent microsomal electron transport. Microsomes catalyzed an NADH-mediated reduction of several electron acceptor dyes, cytochrome c (rotenone insensitive) and methemoglobin. On reduction with dithionite, a cytochrome with an absorbance at approximately 558 nm was observed. Arterial O2-. levels (chemiluminescence) were also reduced by NBT and microsomal electron transport inhibitors. In pulmonary arteries, NBT selectively inhibited PO2 and lactate elicited changes in force generation, presumably by trapping O2-. and preventing H2O2 formation. Thus these studies are consistent with an involvement of O2-.-derived H2O2 generation via a microsomal NADH-cytochrome b558 electron transport system in calf pulmonary artery smooth muscle PO2 and lactate-elicited tone responses.

Animals↗
PubMed1991

Cutaneous NAD(P)H: quinone reductase: a xenobiotica-metabolizing enzyme with potential cancer and oxidation stress-protecting properties.

The toxicity of quinones--including certain chemotherapeutic agents such as doxorubicin--have been related to the enzymatic or nonenzymatic formation of the corresponding semiquinones and their subsequent reaction with molecular oxygen yielding superoxide anion radicals by spontaneous regenerating of the quinones. This semiquinone redox cycling is prevented by the NAD(P)H:quinone reductase (NQR; EC 1.6.99.2) because it mediates a 2-electron reduction which results in the formation of hydroquinones instead of semiquinones. Interestingly, inducers of this enzyme such as butylated hydroxytoluene protect against the severe ulceration of accidental infiltration of doxorubicin into the area around the intravenous infusion. Recently, it has been shown that this highly protective enzyme has a very high basal activity in the epidermis which is in the same range as in the liver. The human gene of the NQR is localized on chromosome 16 and has been cloned recently as well as the gene of the murine liver NQR. We determined NQR in the cytoplasma of murine skin, liver, and human keratinocytes using 2,6-dichlorophenol-indophenol as substrate. In order to characterize this enzyme, induction by polycyclic hydrocarbones and inhibition with several known inhibitors of dihydrodiol dehydrogenase, aldo-keto and carbonyl reductase activities were determined. There was a similar pattern of inhibition of the basal and induced activity in all tissues so far investigated. Pyrazole, progesterone and phenobarbital did not inhibit; however, rutin and indomethacin inhibited dose-dependently. The most potent inhibitor was dicoumarol. These findings suggest that the same enzymatic form is present in liver and skin, and in murine skin and human keratinocytes.

Animals↗
PubMed1995

H2O2 determination in rat lens: chemiluminescent versus radioisotopic methods.

Hydrogen peroxide levels have been determined in rat lenses by using two methods, a chemiluminescent and a radioisotopic method. The average content was found to be 155 +/- 20 and 127 +/- 18 nmol/g wet weight of the tissue, respectively, by the two methods. The reaction of H2O2 with dichlorophenol-indophenol in the presence of peroxidase was also studied. However, this was found to be less suitable. The results of the chemiluminescent determinations are similar to the results with the radioisotopic methods demonstrating the feasibility of determining H2O2 by chemiluminescence measurement as well.

2,6-Dichloroindophenol↗
PubMed2001

High prevalence of G6PD deficiency in Vataliya Prajapati community in western India.

OBJECTIVE: Sporadic cases of drug-induced haemolytic anaemia due to glucose-6-phosphate dehydrogenase (G6PD) deficiency in patients belonging to Vataliya Prajapati community prompted us to study the prevalence of G6PD deficiency in the community. METHODS: Screening for G6PD deficiency was carried out using the dichlorophenol-indophenol (DPIP) dye decolorization method. RESULTS: A total of 471 individuals were screened. Of these, 385 unrelated individuals were considered to calculate the prevalence of G6PD deficiency. Among 272 unrelated males, 76 persons (27.94%) and among 113 unrelated females, 11 individuals (9.73%) were found to be G6PD deficient. A quantitative assay on 41 of the G6PD deficient samples showed the enzyme activity ranged from 0-0.5 unit/ml RBC/min. CONCLUSION: The prevalence of G6PD deficiency in Vataliya Prajapatis community was found to be the highest ever reported in the Indian caste-groups population studied so far.

Anemia, Hemolytic↗
PubMed2002

Measurement of microbial activity in soil by colorimetric observation of in situ dye reduction: an approach to detection of extraterrestrial life.

BACKGROUND: Detecting microbial life in extraterrestrial locations is a goal of space exploration because of ecological and health concerns about possible contamination of other planets with earthly organisms, and vice versa. Previously we suggested a method for life detection based on the fact that living entities require a continual input of energy accessed through coupled oxidations and reductions (an electron transport chain). We demonstrated using earthly soils that the identification of extracted components of electron transport chains is useful for remote detection of a chemical signature of life. The instrument package developed used supercritical carbon dioxide for soil extraction, followed by chromatography or electrophoresis to separate extracted compounds, with final detection by voltammetry and tandem mass-spectrometry. RESULTS: Here we used Earth-derived soils to develop a related life detection system based on direct observation of a biological redox signature. We measured the ability of soil microbial communities to reduce artificial electron acceptors. Living organisms in pure culture and those naturally found in soil were shown to reduce 2,3-dichlorophenol indophenol (DCIP) and the tetrazolium dye 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide inner salt (XTT). Uninoculated or sterilized controls did not reduce the dyes. A soil from Antarctica that was determined by chemical signature and DNA analysis to be sterile also did not reduce the dyes. CONCLUSION: Observation of dye reduction, supplemented with extraction and identification of only a few specific signature redox-active biochemicals such as porphyrins or quinones, provides a simplified means to detect a signature of life in the soils of other planets or their moons.

Bacteria↗
PubMed2006

Cerebrospinal fluid adenosine deaminase activity: a complimentary tool in the early diagnosis of tuberculous meningitis.

BACKGROUND: Tuberculous meningitis (TBM) is the commonest form of neurotuberculosis caused by Mycobacterium tuberculosis bacilli (MTB). The diagnosis of TBM is often difficult. A reliable, cost-effective and rapid diagnostic test, which can be performed in any standard pathology laboratory, could be of help in the diagnosis of TBM. In the present study we measured the adenosine deaminase (ADA) activity in cerebrospinal fluid (CSF) of TBM and non-TBM patients. METHOD: ADA activity in CSF was determined according to a method based on the Berthlot reaction, which is the formation of a colored indophenol complex from ammonia liberated from adenosine, and quantified spectrophotometrically. RESULTS: The CSF ADA activity from TBM patients was compared with CSF ADA from non-TBM infectious meningitis patients, and from patients with non-infectious neurological disorders. The mean CSF ADA activity was found to be significantly higher in CSF of TBM patients, 14.31 +/- 3.87 (2.99-26.94), mean +/- SD with range, than in the CSF from non-TBM infectious meningitis, 9.25 +/- 2.14 (4.99-13.96) and from the non-infectious neurological disorders group, 2.71 +/- 1.96 (0.00-7.68), P < 0.0001 for both comparisons. A cut-off value of 11.39 U/L/min for the TBM patients was calculated from the mean + SD of the non-TBM patients. The ADA test gave a sensitivity of 82% and a specificity of 83% for infectious TBM when this cut-off value was used. CONCLUSION: This study demonstrated that ADA activity in the CSF of TBM patients, using a cut-off value 11.39 U/L/min, can be useful for the early differential diagnosis of TBM. This test can be performed in any pathology laboratory where more sophisticated methods are not available.

Journal Article↗
PubMed2000

Effects of lanthanum and calcium on photoelectron transport activity and the related protein complexes in chloroplast of cucumber leaves.

The effects of lanthanum and calcium ions on electron transport, dichlorephenol indophenol (DCIP) photoreduction, and oxygen evolution activities in chloroplast from cucumber (Cucumis satives L.) were determined. The lanthanum inhibited the whole electron chain-transport activity of chloroplast. DCIP photoreduction and oxygen evolution activities of the photosystem I (PSII) also decrease after treatment with La3+. But the diminished activities of PSII and chloroplast caused by La3+ could be reversed by Ca2+ and even became higher than the control level. The concentration analysis of related protein complexes to photoelectron transport in chloroplast included that La3+ induced the concentration of chlorophyll protein complexes increasing but caused some nonchlorophyll protein complexes to decompose partially. This increasing effect of La3+ on chlorophyll protein complexes results in the improvement of chlorophyll content, which will improve the absorption of photoelectron and energy transport in the process of photosynthesis.

2,6-Dichloroindophenol↗
PubMed1988

Reductions of 2-enals, dehydrogenation of saturated aldehydes and their racemisation.

Enoate reductase or clostridia containing this enzyme (Clostridium tyrobutyricum or C. kluyveri) catalyse the reduction of alpha,beta-unsaturated aldehydes (enals). The enantiomeric purity of the saturated aldehydes obtained from alpha-substituted enals is usually rather low and depends heavily on the reaction conditions. The reduction of the corresponding allyl alcohols to the saturated alcohols leads to much higher enantiomeric purities, though the reduction of the enal corresponding to the allyl alcohol to the saturated aldehyde is an intermediary step in the reaction sequence allyl alcohol----saturated alcohol. The explanation seems to be the racemisation of saturated aldehydes caused by enoate reductase. This is illustrated by the reduction of (E)-2-methylcinnamyl aldehyde to (R)-2-methyl-3-phenylpropanal or (R)-2-methyl-3-phenylpropanol under different conditions and measuring the racemisation of the aldehyde as well as the hydrogen-deuterium exchange of 3-phenylpropanal. In contrast to saturated carboxylates saturated aldehydes can be dehydrogenated to alpha,beta-unsaturated aldehydes (enals) by enoate reductase in the presence of electron acceptors such as oxygen or dichlorophenol indophenol. Under these conditions enoate reductase shows in the presence of oxygen a surprisingly high half life (greater than 20 h) as compared to that which is observed when the enzyme was used as a reductase with NADH in the presence of oxygen. In this case the enzyme is inactivated within a few minutes.

Aldehydes↗
PubMed1978

Evaluation of the enzymatic ammonia method for urine on the Du Pont automatic clinical analyzer.

The enzymatic method for ammonia with the Du Pont Automatic Clinical Analyzer was tested in our laboratory. The method is very suitable for urine samples although the method was released by Du Pont only for plasma samples. The results correlated well with those obtained by a method based on the Berthelot indophenol reaction and by a method based on the use of an ammonium electrode, which has an ammonium ion selective membrane. The day-to-day coefficient of variation is about 2 and 4% at concentration levels of 100 and 50 mumol/1 respectively. The measured and relative ammonia concentration are linearly related. Recovery of added known amounts of ammonium is complete and no interference from glucose, urea, creatinine and uric acid could be demonstrated. Recommendations are given for handling blood and urine samples before analysis.

Ammonia↗
PubMed1979

Inhibition of the nitrate reductase complex by dibromothymoquinone.

The plastoquinone antagonist 2,5-dibromothymoquinone was found to inhibit NO-3 reduction from NADH by the nitrate reductase complex from wheat. It accepts electrons from NADH through the NADH dehydrogenase activity of the nitrate reductase. However, it does not inhibit the reduction of 2,6-dichlorophenol-indophenol by the enzyme. This suggests that the two compounds may be accepting electrons at different places from the enzyme. Further it was observed that reduced DCIP could be oxidized by DBMIB in the absence of NADH indicating that the electron flow in the nitrate reductase complex may take place in a unidirectional way.

Dibromothymoquinone↗
PubMedDate not supplied

Cataract induction by 1,2-naphthoquinone. I. Studies on the redox properties of bovine lens proteins.

Conditions of oxidative stress may lead to cataract formation. Reaction of certain flavoproteins, the NADH: oxidoreductases, with different quinones is well known to form hydrogen-peroxide. This reaction was investigated to get more information on cataract induction by naphthalene and its quinone metabolites. Protein extracts from bovine lens cortex exhibit "diaphorase" activity, indicated as dye reduction in the presence of NADH and dichlorophenol-indophenol (DCPIP) or ferricyanide. Different redox cycling compounds are shown to be active in this "diaphorase" reaction by lens protein extract (LCE): Oxygen consumption can be detected in the presence of pyrroloquinoline quinone and juglone whereas 1,4-naphthoquinone, menadione and paraquat are no redox cyclists in this flavoprotein catalyzed reaction.

Animals↗
PubMedDate not supplied

Tricarboxylic acid cycle enzymes of the ectomycorrhizal basidiomycete, Suillus bovinus.

In crude cell extracts of the ectomycorrhizal fungus, Suillus bovinus, activities of citrate synthase, aconitase, isocitrate dehydrogenase, succinate dehydrogenase, fumarase, and malate dehydrogenase have been proved and analyzed. Citrate synthase exhibited high affinities for both its substrates: oxaloacetate (Km = 0.018 mM) and acetyl-CoA (Km = 0.014 mM). Aconitase showed better affinity for isocitrate (Km = 0.62 mM) than for citrate (Km = 3.20 mM). Analysis of isocitrate dehydrogenase revealed only small maximum activity (60 nmol x mg protein(-1) x min(-1)), the enzyme being exclusively NADP+-dependent. Using the artificial electron acceptor dichlorophenol indophenol, activity and substrate affinity of succinate dehydrogenase were rather poor. Fumarase proved Fe2+-independent. Its affinity for malate was found higher (Km = 1.19 mM) than that for fumarate (Km = 2.09 mM). High total activity of malate dehydrogenase could be separated by native PAGE into a slowly running species of (mainly) cytosolic (about 80%) and a faster running species of (mainly) mitochondrial origin. Affinities for oxaloacetate of the two enzyme species were found identical within limits of significance (Km = 0.24 mM and 0.22 mM). The assumed cytosolic enzyme exhibited affinity for malate (Km = 5.77 mM) more than one order of magnitude lower than that for oxaloacetate. FPLC on superose 12 revealed only one activity band at a molecular mass of 100 +/- 15 kDa. Activities of 2-oxoglutarate dehydrogenase and of succinyl-CoA synthetase could not be found. Technical problems in their detection, but also existence of an incomplete tricarboxylic acid cycle are considered. Metabolite affinities, maximum activities and pH-dependences of fumarase and of malate dehydrogenase allow the assumption of a reductive instead of oxidative function of these enzymes in vivo.

Aconitate Hydratase↗
PubMed2005

Atomic absorption spectrometry for the automatic indirect determination of ascorbic acid based on-the reduction of manganese dioxide.

A new and simple flow injection method followed by atomic absorption spectrometry has been developed for the indirect determination of ascorbic acid. The proposed method is based on oxidation of ascorbic acid to dehydroascorbic acid using a solid-phase manganese dioxide (30% m/m suspended on silica gel beads) reactor. The flow of the sample through the column reduces the MnO2 to Mn(II) in an acidic carrier stream of 6.3 mM HNO3 (pH 2.2) with flow rate of 4.0 ml/min at room temperature; Mn(II) is measured by atomic absorption spectrometry. The absorbance of Mn(II) is proportional to the concentration of ascorbic acid in the sample. The calibration curve was linear up to 30 mg/L, with a detection limit of 0.2 mg/L for a 220 microL injected sample volume. The developed procedure was found to be suitable for the determination of AsA in pharmaceuticals and foods with a relative standard deviation better than 1.09% and a sampling rate of about 95 h(-1). The results exhibit no interference from the presence of large amounts of organic compounds. The reliability of the method was established by parallel determination against the 2,6-dichlorophenol-indophenol methods.

Ascorbic Acid↗
PubMed1983

The fate of dibenz[b,f]-1,4-oxazepine (CR) in the rat. Part II. Metabolism in vitro.

CR (dibenz[b,f]-1,4-oxazepine) is metabolized by rat liver 105 000 g supernatant fractions by (a) ring opening and reduction to 2-amino-2'-hydroxymethyldiphenyl ether and (b) oxidation at C11 to give a cyclic lactam. Reaction (a) is NADPH-dependent, decreased by dialysis and methylene blue, whereas reaction (b) is heat-resistant, inactivated by dialysis, inhibited by CN-, p-chloromercuribenzoate, amytal and menadione, and stimulated by methylene blue, phenazine methosulphate and 2,6-dichlorophenol indophenol. Reaction (a) is similar to that of aldehyde reductases (E.C.1.1.1.2) and reaction (b) to that of molybdenum hydroxylases (E.C.1.2.3.1). Reaction (a) is also catalysed by an NADH-dependent enzyme in liver microsomes and subsequent hydroxylation of the lactam also occurs in this cell fraction. Some extrahepatic metabolism of CR occurs via the same routes in kidney, small intestine and lung, though the yield is limited. Digestive gland extract of Helix pomatia converts CR to its lactam in significant amounts. The metabolism of CR in vitro is similar to that predicted from observations in vivo.

Animals↗
PubMed1987

Effects of oxygen free radical scavengers on the membrane myoinositol dehydrogenase of Bacillus pumilus strain 5.

Micromolar amounts of superoxide dismutase (SOD) or parabenzoquinone (PBQ) inhibit the membrane-bound myoinositol dehydrogenase of Bacillus pumilus strain 5 in the mode of this enzyme transferring electrons to 2,6-dichlorophenol indophenol (DCPIP). The inhibition trends are similar to those reported earlier by us for the inhibition by mannitol and benzoate. We postulate that the transfer of electrons from the enzyme to DCPIP involves in its rate-limiting step, a catalytic intermediate in the nature of superoxide (O2-) and/or hydroyl free radical (OH.). Scavenging of any one or both of these radicals, therefore, inhibits the electron transfer reaction. PBQ serves as an electron sink in the reaction preventing the reduction of DCPIP.

Bacillus↗
PubMed1995

Enhanced luminescence study of liver homogenate response to oxidative stress.

An enhanced luminescence technique was used to monitor the response of liver homogenates stressed with sodium perborate. Rat liver homogenates were subjected to oxidative stress with sodium perborate, and the light signals, generated by a suitable system, containing luminol and compounds producing enhancement of light emission such as sodium benzoate and indophenol, were detected by a luminometer. The intensity of light emission (E) was found dependent on homogenate concentration (C). When C increased, E at first increased as well and, then, decreased rapidly. The graphic expression of this phenomenon resulted as a curve that can be described by the equation: E = a.C/exp(b.C). It is proposed that the a value represents the capacity of the tissue to catalyze the production of .OH radical species. The b value might be related to the capacity of the tissue to scavenge such radicals, since it increases when homogenates are supplemented with antioxidants and decreases when homogenates are treated with prooxidant. The results obtained by supplementing homogenates with iron containing substances, or using model systems, suggest that cell substances catalyzing the luminescent reaction, such as the hemoproteins, are "scavengers" as well as radical producers. The concentration-emission curve obtained with suitable model system is described by the equation: E = a.C/exp(b.Ck). It is suggested that, using the k value, information can be obtained on the relative capacity of hemoproteins and antioxidant systems to interact with .OH radicals.

Animals↗