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1

Tyrosinase and Catechol Oxidase  

Microsoft Academic Search

THE nature of tyrosinase has been under discussion for a very long time. Raper and his school1, Graubard and Nelson2, and Keilin and Mann3 believe it to be a distinct enzyme, different from catechol oxidase. Onslow and Robinson4, McCance5, and Richter6 believe it to be a catechol oxidase plus o-chinone plus dehydrogenase. Kubowitz7, whose work appeared in a recent issue

L. Califano; D. Kertesz

1938-01-01

2

Catechol oxidase — structure and activity  

Microsoft Academic Search

Recently determined structures of copper-containing plant catechol oxidase in three different catalytic states have provided new insights into the mechanism of this enzyme and its relationship to other copper type-3 proteins. Moreover, the active site of catechol oxidase has been found to be structurally conserved with the oxygen-binding site of a molluscan hemocyanin.

Christoph Eicken; Bernt Krebs; James C Sacchettini

1999-01-01

3

The catalytic cycle of catechol oxidase  

Microsoft Academic Search

Hybrid density functional theory with the B3LYP functional has been used to investigate the catalytic mechanism of catechol oxidase. Catechol oxidase belongs to a class of enzymes that has a copper dimer with histidine ligands at the active site. Another member of this class is tyrosinase, which has been studied by similar methods previously. An important advantage for the present

Per E. M. Siegbahn

2004-01-01

4

Coniferyl alcohol oxidase — a catechol oxidase?  

Microsoft Academic Search

The physico-chemical properties of coniferyl alcohol oxidase (CAO), a copper containing glycoprotein spatiotemporally associated with lignification in conifers, is reported here. By electron paramagnetic resonance spectroscopy, only type 3 copper was indicated in CAO. CAO oxidizes several laccase substrates; however, it is not a blue-copper protein and monoclonal antibodies against both native and deglycosylated CAO did not recognize any of

Preethi V. Udagama-Randeniya; Rodney A. Savidge

1995-01-01

5

Discovery of a new tyrosinase-like enzyme family lacking a C-terminally processed domain: production and characterization of an Aspergillus oryzae catechol oxidase  

Microsoft Academic Search

A homology search against public fungal genome sequences was performed to discover novel secreted tyrosinases. The analyzed\\u000a proteins could be divided in two groups with different lengths (350–400 and 400–600 residues), suggesting the presence of\\u000a a new class of secreted enzymes lacking the C-terminal domain. Among them, a sequence from Aspergillus oryzae (408 aa, AoCO4) was selected for production and

Chiara Gasparetti; Greta Faccio; Mikko Arvas; Johanna Buchert; Markku Saloheimo; Kristiina Kruus

2010-01-01

6

Chemical tools for mechanistic studies related to catechol oxidase activity  

Microsoft Academic Search

Important questions remain unanswered concerning the catalytic mechanism of catechol oxidase, an enzyme with a coupled dinuclear copper active site, which catalyzes the oxidation of o-diphenols to o-quinones in presence of dioxygen. In this review we try to demonstrate how well-suited biomimetic models could help elucidate the mechanistic pathway involved in the catalytic cycle of the enzyme. Moreover, the use

Catherine Belle; Katalin Selmeczi; Stéphane Torelli; Jean-Louis Pierre

2007-01-01

7

Leaf peroxidase and catechol oxidase polymorphism and the identification of commercial apple varieties  

Microsoft Academic Search

Isozyme electrophoresis, using poly?acrylamide gradient gel electrophoresis has been applied to leaf extracts from 12 commercial apple varieties. The oxidative enzymes peroxidase and catechol oxidase show sufficient polymorphism to allow unique identification of most of the varieties tested.

M. F. Barnes

1993-01-01

8

A flexible hydroxy-bridged dicopper complex as catechol oxidase mimic  

Microsoft Academic Search

A flexible hydroxy-bridged dicopper complex with isoindoline ligand has prepared and characterized and shown that it does not maintain its dimeric nature when catalyzing catechol oxidase-like reaction.

Tamás Csay; Balázs Kripli; Michel Giorgi; József Kaizer; Gábor Speier

2010-01-01

9

Comparative modeling of the latent form of a plant catechol oxidase using a molluskan hemocyanin structure  

Microsoft Academic Search

The structure of the precursor form of catechol oxidase from sweet potatoes (Ipomoea batatas) has been modeled on the basis of the 3D structural data of mature catechol oxidase [Nat. Struct. Biol. 5 (1998) 1084] and of hemocyanin from giant octopus (Octopus dofleini) [J. Mol. Biol. 278 (1998) 855]. A C-terminal extension peptide is found in the cDNA sequence but

Carsten Gerdemann; Christoph Eicken; Hans-Joachim Galla; Bernt Krebs

2002-01-01

10

Limitations of the quantitative cytochemical assay of catechol oxidase in melanoma cells  

Microsoft Academic Search

Summary  The cytochemical quantification of catechol oxidase activity in fixed B16 melanoma cells was investigated using dopa as the substrate. Inhibitors showed that peroxidases do not significantly interfere. The kinetics of melanin formation were studied initially in solution with purified catechol oxidase. Two key parameters were identified: lag-time and the rate of melanin formation. The lag-time was taken as the time

A. C. Croce; G. Bottiroli; E. Prosperi; R. Supino; P. J. Stoward

1988-01-01

11

Purification and spectroscopic studies on catechol oxidase from lemon balm (Melissa officinalis).  

PubMed

A catechol oxidase from lemon balm (Melissa officinalis) moCO which only catalyzes the oxidation of catechols to quinones without hydroxylating tyrosine was purified. The molecular mass of the M. officinalis enzyme of 39,370 Da was obtained by MALDI mass spectrometry and the isoelectric point was determined to be 3.4. Addition of 2 eq. H(2)O(2) to the enzyme leads to oxy catechol oxidase. In the UV/Vis spectrum two new absorption bands occur at 343 nm (?=8510 M(-1)cm(-1)) and 580 nm (?=580 M(-1)cm(-1)) due to O(2)(2-)Cu (II) charge transfer transitions in accordance with the oxy forms of other type 3 copper proteins. The N-terminal sequence has been determined by Edman degradation to NPVQAPELDKCGTAT, exhibiting a proline at the second and sixth position conserved in other polyphenol oxidases. PMID:22727580

Rompel, Annette; Büldt-Karentzopoulos, Klaudia; Molitor, Christian; Krebs, Bernt

2012-09-01

12

THE GENETIC CONTROL AND BIOCHEMICAL MODIFICATION OF CATECHOL OXIDASE IN MAIZE  

Microsoft Academic Search

Three isozyme variants of catechol oxidase have been shown to be deter- mined by alleles of a gene, Cz, which has been located on chromosome 10 less than 0.1 recombination units from the endosperm marker &,.-The ex- tractable form of the enzyme is modified by an endogeneous \\

TONY PRYOR

13

Enzymatic dynamics of catechol oxidase from Gastrolina depressa  

Microsoft Academic Search

Properties of the phenoloxidase (PO) from adult of Gastrolina depressa Baly (Coleoptera: Chrysomelidae) as well as effects of some metal ions and inhibitors on the activity of PO purified by (NH4)2SO4 were determined. The optimal pH and temperature of the enzyme for the oxidation of catechol were determined to be at pH 7.5 and at 40°C, respectively. The kinetic parameters

Yan Zhao; Chao-Bin Xue; Long Yang; Cheng-Gang Zhou; Wan-Chun Luo

2010-01-01

14

Egg Capsule Catechol Oxidase from the Little Skate Raja erinacea Mitchill, 1825  

Microsoft Academic Search

A phenoloxidase was demonstrated in cx tracts ofegg capsules tanning in utero and of nidamental glands from spawning little skate, Raja eninacea. The en zyme was identified as a catechol oxidase based on its ability to oxidize the ortho-diphenols pyrocatechol, 4-methylcatechol, 3,4-dihydroxyphenylalanine, 3-hy droxytyramine and N-acetyldopamine to their corre sponding ortho-quinones and its relative inactivity against monophenols. 4-methylcatechol was oxidized

THOMAS J. KOOB; Mount Desert; Salsbury Cove

1988-01-01

15

Crystal structure of a plant catechol oxidase containing a dicopper center  

Microsoft Academic Search

Catechol oxidases are ubiquitous plant enzymes containing a dinuclear copper center. In the wound-response mechanism of the plant they catalyze the oxidation of a broad range of ortho-diphenols to the corresponding o-quinones coupled with the reduction of oxygen to water. The crystal structures of the enzyme from sweet potato in the resting dicupric Cu(II)-Cu(II) state, the reduced dicuprous Cu(I)-Cu(I) form,

Thomas Klabunde; Christoph Eicken; James C. Sacchettini; Bernt Krebs

1998-01-01

16

PURIFICATION AND CLONING OF THE SALIVARY PEROXIDASE\\/CATECHOL OXIDASE OF THE MOSQUITO ANOPHELES ALBIMANUS  

Microsoft Academic Search

Salivary homogenates of the adult female mosquito Anopheles albimanus have been shown previously to contain a vasodilatory activity associated with a catechol oxidase\\/peroxidase activity. We have now purified the salivary peroxidase using high-performance liquid chromatography. The pure enzyme is able to relax rabbit aortic rings pre-constricted with norepinephrine. The peroxidase has a relative molecular mass of 66 907 as estimated

JOSÉ M. C. RIBEIRO; JESUS G. VALENZUELA

17

The studies of FT-IR and CD spectroscopy on catechol oxidase I from tobacco  

Microsoft Academic Search

A novel copper-containing enzyme named COI (catechol oxidase I) has been isolated and purified from tobacco by extracting acetone-emerged powder with phosphate buffer, centrifugation at low temperature, ammonium sulfate fractional precipitation, and column chromatography on DEAE-sephadex (A-50), sephadex (G-75), and DEAE-celluse (DE-52). PAGE, SDS-PAGE were used to detect the enzyme purity, and to determine its molecular weight. Then the secondary

Hourong Xiao; Yongshu Xie; Qingliang Liu; Xiaolong Xu; Chunhua Shi

2005-01-01

18

Inhibition of NADPH oxidase activation in endothelial cells by ortho-methoxy-substituted catechols.  

PubMed

NADPH oxidase is a major enzymatic source of oxygen free radicals in stimulated endothelial cells (ECs). The ortho-methoxy-substituted catechol, apocynin (4-hydroxy-3-methoxyacetophenone), isolated from the traditional medicinal plant Picrorhiza kurroa, inhibits the release of superoxide anion (O2*-) by this enzyme. The compound acts by blocking the assembly of a functional NADPH oxidase complex. The underlying chemistry of this inhibitory activity, and its physiological significance to EC proliferation, have been investigated. A critical event is the reaction of ortho-methoxy-substituted catechols with reactive oxygen species (ROS) and peroxidase. Analysis of this reaction reveals that apocynin is converted to a symmetrical dimer through the formation of a 5,5' carbon-carbon bond. Both reduced glutathione and L-cysteine inhibit this dimerization process. Catechols without the ortho-methoxy-substituted group do not undergo this chemical reaction. Superoxide production by an endothelial cell-free system incubated with apocynin was nearly completely inhibited after a lagtime for inhibition of ca. 2 min. Conversely, O2*- production was nearly completely inhibited, without a lagtime, by incubation with the dimeric form of apocynin. The apocynin dimer undergoes a two-electron transfer reaction with standard redox potentials of -0.75 and -1.34 V as determined by cyclic voltammetry. Inhibition of endothelial NADPH oxidase by apocynin caused a dose-dependent inhibition of cell proliferation. These findings identify a metabolite of an ortho-methoxy-substituted catechol, which may be the active compound formed within stimulated ECs that prevents NADPH oxidase complex assembly and activation. PMID:12380644

Johnson, David K; Schillinger, Kurt J; Kwait, David M; Hughes, Chambers V; McNamara, Erin J; Ishmael, Fauod; O'Donnell, Robert W; Chang, Ming-Mei; Hogg, Michael G; Dordick, Jonathan S; Santhanam, Lakshmi; Ziegler, Linda M; Holland, James A

2002-01-01

19

Limitations of the quantitative cytochemical assay of catechol oxidase in melanoma cells.  

PubMed

The cytochemical quantification of catechol oxidase activity in fixed B16 melanoma cells was investigated using dopa as the substrate. Inhibitors showed that peroxidases do not significantly interfere. The kinetics of melanin formation were studied initially in solution with purified catechol oxidase. Two key parameters were identified: lag-time and the rate of melanin formation. The lag-time was taken as the time required by intermediates to reach a critical concentration at which the polymerization process starts and melanin production becomes measurable (at 640 nm). In solution, the lag-time decreases as the enzyme activity increases, particularly when the activity is very low. The rate at which melanin is formed by pure enzyme in solution is independent of dopa concentration when its activity is low but increases linearly with dopa concentration when the activity is comparatively high. In fixed melanoma cells, the lag-time decreases linearly with increases of dopa concentrations up to 20 mM; at concentrations higher than this, the lag decreases more slowly. In contrast, the rate of melanin production is unaffected by changes in dopa concentration. The lag-times of different cells lines incubated at the same substrate concentration decrease as the enzyme activity of the cells increases. The rate of melanin production seems to be affected by factors other than catechol oxidase activity, such as the intracellular organization and distribution of the enzyme. PMID:3147271

Croce, A C; Bottiroli, G; Prosperi, E; Supino, R; Stoward, P J

1988-11-01

20

Isozymes of Ipomoea batatas catechol oxidase differ in catalase-like activity 1 Dedicated to Professor Ernst-Gottfried Jäger on the occasion of his 65th birthday. 1  

Microsoft Academic Search

The amino acid sequences of two isozymes of catechol oxidase from sweet potatoes (Ipomoea batatas) were determined by Edman degradation of BrCN cleavage fragments of the native protein and by sequencing of amplified cDNA fragments. Sequence alignment and phylogenetic analysis of plant catechol oxidases revealed about 80% equidistance between the two I. batatas catechol oxidases and approximately 40–60% to catechol

Carsten Gerdemann; Christoph Eicken; Annette Magrini; Helmut E Meyer; Annette Rompel; Friedrich Spener; Bernt Krebs

2001-01-01

21

Catechol oxidase activity of dicopper complexes with N-donor ligands  

Microsoft Academic Search

The catecholase activity of two dicopper(II) complexes [Cu2(L1)(CF3SO3)2(H2O)4](CF3SO3)2 (1) and [Cu2(L2O)](CF3SO3)](CF3SO3)2 (2) containing the ligands 1,3-bis{N,N-bis(2-[2-pyridyl]ethyl)}aminopropane (L1) and 1,3-bis{N,N-bis(2-[2-pyridyl]ethyl)}amino-2-hydroxypropane (L2OH) was studied as functional as well as structural models for the type 3 copper enzyme, catechol oxidase. The X-ray structure of 1 in solid form shows a Cu?Cu distance of 7.840Ĺ, while in 2 the Cu?Cu distance is only 3.699Ĺ.

Katalin Selmeczi; Marius Réglier; Michel Giorgi; Gábor Speier

2003-01-01

22

Molecular cloning of the isoamyl alcohol oxidase-encoding gene (mreA) from Aspergillus oryzae.  

PubMed

Isoamyl alcohol oxidase (IAAOD) is a novel enzyme that catalyzes the formation of isovaleraldehyde, which is the main component of mureka that gives sake an off-flavor (Yamashita et al. Biosci. Biotechnol. Biochem., 63, 1216-1222, 1999). We cloned the genomic DNA sequence encoding IAAOD from a koji mold, Aspergillus oryzae, using a PCR-amplified DNA fragment corresponding to the partial amino acid sequences of the purified protein as a probe. The cloned gene comprises 1903 bp of an open reading frame with three putative introns and encodes 567 amino acids with a presumed signal peptide consisting of 24 amino acids at the N-terminus. Moreover, nine potential N-glycosylation sites were present. Homology search on amino acid sequence showed that IAAOD has a region significantly similar to those conserved in FAD-dependent oxidoreductases. Southern hybridization analysis revealed that the cloned gene exists as a single copy in the A. oryzae RIB 40 chromosome. The cloned gene was overexpressed under the control of the amyB promoter in A. oryzae. The isovaleraldehyde-producing activity in the culture supernatant of one transformant was over 800 times as high as that of transformant with the control vector. This result demonstrates that the cloned gene encodes IAAOD. We named this novel alcohol oxidase gene "mreA". PMID:16232791

Yamashita, N; Motoyoshi, T; Nishimura, A

2000-01-01

23

Purification and spectroscopic studies on catechol oxidases from Lycopus europaeus and Populus nigra: Evidence for a dinuclear copper center of type 3 and spectroscopic similarities to tyrosinase and hemocyanin  

Microsoft Academic Search

We purified two catechol oxidases from Lycopus europaeus and Populus nigra which only catalyze the oxidation of catechols to quinones without hydroxylating tyrosine. The molecular mass of the Lycopus enzyme was determined to 39?800 Da and the mass of the Populus enzyme was determined to 56?050 Da. Both catechol oxidases are inhibited by thiourea, N-phenylthiourea, dithiocarbamate, and cyanide, but show

Annette Rompel; Helmut Fischer; Dirk Meiwes; Klaudia Büldt-Karentzopoulos; Renée Dillinger; Felix Tuczek; Herbert Witzel; Bernt Krebs

1999-01-01

24

The studies of FT-IR and CD spectroscopy on catechol oxidase I from tobacco  

NASA Astrophysics Data System (ADS)

A novel copper-containing enzyme named COI (catechol oxidase I) has been isolated and purified from tobacco by extracting acetone-emerged powder with phosphate buffer, centrifugation at low temperature, ammonium sulfate fractional precipitation, and column chromatography on DEAE-sephadex (A-50), sephadex (G-75), and DEAE-celluse (DE-52). PAGE, SDS-PAGE were used to detect the enzyme purity, and to determine its molecular weight. Then the secondary structures of COI at different pH, different temperatures and different concentrations of guanidine hydrochloride (GdnHCl) were studied by the FT-IR, Fourier self-deconvolution spectra, and circular dichroism (CD). At pH 2.0, the contents of both ?-helix and anti-parallel ?-sheet decrease, and that of random coil increases, while ?-turn is unchanged compared with the neutral condition (pH 7.0). At pH 11.0, the results indicate that the contents of ?-helix, anti-parallel ?-sheet and ?-turn decrease, while random coil structure increases. According to the CD measurements, the relative average fractions of ?-helix, anti-parallel ?-sheet, ?-turn/parallel ?-sheet, aromatic residues and disulfide bond, and random coil/?-turn are 41.7%, 16.7%, 23.5%, 11.3%, and 6.8% at pH 7.0, respectively, while 7.2%, 7.7%, 15.2%, 10.7%, 59.2% at pH 2.0, and 20.6%, 9.5%, 15.2%, 10.5%, 44.2% at pH 11.0. Both ?-helix and random coil decrease with temperature increasing, and anti-parallel ?-sheet increases at the same time. After incubated in 6 mol/L guanidine hydrochloride for 30 min, the fraction of ?-helix almost disappears (only 1.1% left), while random coil/?-turn increases to 81.8%, which coincides well with the results obtained through enzymatic activity experiment.

Xiao, Hourong; Xie, Yongshu; Liu, Qingliang; Xu, Xiaolong; Shi, Chunhua

2005-10-01

25

Tuning the activity of catechol oxidase model complexes by geometric changes of the dicopper core.  

PubMed

Dicopper(II) complexes of a series of different pyrazolate-based dinucleating ligands [L1](-)-[L4](-) have been synthesized and characterized structurally and spectroscopically. A major difference between the four complexes is the individual metal-metal separation that is enforced by the chelating side arms of the pyrazolate ligand scaffold: it varies from 3.45 A in 2 x (BF4)4 to 4.53 A in 4 x (ClO4)2. All complexes have been evaluated as model systems for the catechol oxidase enzyme by using 3,5-di-tert-butylcatechole (DTBC) as the test substrate. They were shown to exhibit very different catecholase activities ranging from very efficient to poor catalysts (k(obs) between 2430+/-202 and 22.8+/-1.2 h(-1)), with an order of decreasing activity 2 x (ClO4)4 > 1 x (ClO4)2 > 3 x (ClO4)2 > 4 x (ClO4)2. A correlation of the catecholase activities with the variation in Cu...Cu distances, as well as other effects resulting from the distinct redox potentials, neighboring groups, and the individual coordination spheres are discussed. Saturation behavior for the rate dependence on substrate concentration was observed in only two cases, that is, for the most active 2 x (ClO4)4 and for the least active 4 x (ClO4)2, whereas a catalytic rate that is almost independent of substrate concentration (within the range studied) was observed for 1 x (ClO4)2 and 3 x (ClO4)2. H2O2 was detected as the product of O2 reduction in the catecholase reaction of the three most active systems. The structures of the adducts of "L3Cu2" and "L4Cu2" with a substrate analogue (tetrachlorocatecholate, TCC) suggest a bidentate substrate coordination to only one of the copper ions for those catalysts that feature short ligand side arms and correspondingly exhibit larger metal-metal separations; this possibly contributes to the lower activity of these systems. TCC binding is supported by several H-bonding interactions to water molecules at the adjacent copper or to ligand-side-arm N-donors; this emphasizes the importance of functional groups in proximity to the bimetallic active site. PMID:11822456

Ackermann, Jens; Meyer, Franc; Kaifer, Elisabeth; Pritzkow, Hans

2002-01-01

26

Mechanistic insight into the catechol oxidase activity by a biomimetic dinuclear copper complex.  

PubMed

The biomimetic catalytic oxidation of 3,5-di- tert-butylcatechol by the dicopper(II) complex of the ligand alpha,alpha'-bis(bis[1-(1'-methyl-2'-benzimidazolyl)methyl]amino)- m-xylene in the presence of dioxygen has been investigated as a function of temperature and pH in a mixed aqueous/organic solvent. The catalytic cycle occurs in two steps, the first step being faster than the second step. In the first step, one molecule of catechol is oxidized by the dicopper(II) complex, and the copper(II) centers are reduced. From the pH dependence, it is deduced that the active species of the process is the monohydroxo form of the dinuclear complex. In the second step, the second molecule of catechol is oxidized by the dicopper(I)-dioxygen complex formed upon oxygenation of the reduced complex. In both cases, catechol oxidation is an inner-sphere electron transfer process involving binding of the catechol to the active species. The binary catechol-dicopper(II) complex formed in the first step could be characterized at very low temperature (-90 degrees C), where substrate oxidation is blocked. On the contrary, the ternary complex of dicopper(I)-O(2)-catechol relevant to the second step does not accumulate in solution and could not be characterized, even at low temperature. The investigation of the biphasic kinetics of the catalytic reaction over a range of temperatures allowed the thermodynamic (Delta H degrees and Delta S degrees ) and activation parameters (Delta H( not equal) and Delta S( not equal)) connected with the key steps of the catecholase process to be obtained. PMID:15449133

Granata, Alessandro; Monzani, Enrico; Casella, Luigi

2004-10-01

27

Plasma catechols and monoamine oxidase metabolites in untreated Parkinson's and Alzheimer's diseases  

Microsoft Academic Search

Prior studies have documented functional and pathological compromise of the peripheral sympathetic nervous system in patients with Parkinson's disease, suggesting the possibility of reduced catecholamine release into the circulation. We measured free plasma catechols in early and untreated patients with Parkinson's disease, but found no evidence of reduced concentrations, compared to control subjects or a group of patients with probable

J. Eric Ahlskog; Ryan J. Uitti; Gertrude M. Tyce; John F. O'Brien; Ronald C. Petersen; Emre Kokmen

1996-01-01

28

Catechol oxidase model compounds based on aminocarbohydrates: new structure types and investigations on the catalytic reaction  

Microsoft Academic Search

Recently, we reported the structure and properties of several copper(II) complexes with aminocarbohydrate-based ligands. Four of these complexes are capable of catalyzing the oxidation of 3,5-di-tbutyl-catechol (dtbc) to the corresponding quinone. The present work contains new compounds of this ligand series of which most form different structure types than the previously described. Investigations on the influence of possible inhibitors like

Rainer Wegner; Michael Gottschaldt; Wolfgang Poppitz; Ernst-G. Jäger; Dieter Klemm

2003-01-01

29

Mechanistic insight into the catechol oxidase activity by a biomimetic dinuclear copper complex  

Microsoft Academic Search

The biomimetic catalytic oxidation of 3,5-di- tert-butylcatechol by the dicopper(II) complex of the ligand ?,??-bis{bis[1-(1?-methyl-2?-benzimidazolyl)methyl]amino}- m-xylene in the presence of dioxygen has been investigated as a function of temperature and pH in a mixed aqueous\\/organic solvent. The catalytic cycle occurs in two steps, the first step being faster than the second step. In the first step, one molecule of catechol

Alessandro Granata; Enrico Monzani; Luigi Casella

2004-01-01

30

Plasma catechols and monoamine oxidase metabolites in untreated Parkinson's and Alzheimer's diseases.  

PubMed

Prior studies have documented functional and pathological compromise of the peripheral sympathetic nervous system in patients with Parkinson's disease, suggesting the possibility of reduced catecholamine release into the circulation. We measured free plasma catechols in early and untreated patients with Parkinson's disease, but found no evidence of reduced concentrations, compared to control subjects or a group of patients with probable Alzheimer's disease. Rather, there was a significant elevation of plasma norepinephrine within the Parkinson's disease group. Furthermore, 6 of 15 untreated Parkinson's disease patients (40%) displayed markedly elevated plasma concentrations of the catecholamine MAO metabolites, DOPAC or DOPEG. Despite this finding, platelet MAO-B activity measured in these and all other Parkinson's disease patients fell well within the range of the control subjects, and was also statistically similar to the group with Alzheimer's type dementia. Plasma dopa levels were similar in all groups, whereas the majority of patients in the three groups had plasma free dopamine and epinephrine concentrations below the limits of detection. These trends toward increased, rather than decreased, circulating catechol concentrations suggest that peripheral sympathetic nervous system catecholamine production and release is not severely compromised in patients with early Parkinson's disease. In addition, we were unable to confirm certain previous reports of elevated MAO-B activity in patients with Parkinson's or Alzheimer's diseases. PMID:8815165

Ahlskog, J E; Uitti, R J; Tyce, G M; O'Brien, J F; Petersen, R C; Kokmen, E

1996-03-01

31

Biochemical and spectroscopic characterization of catechol oxidase from sweet potatoes ( Ipomoea batatas) containing a type-3 dicopper center 1 In memoriam to Prof. Dr. Dr. H. Witzel. 1  

Microsoft Academic Search

Two catechol oxidases have been isolated from sweet potatoes (Ipomoea batatas) and purified to homogeneity. The two isozymes have been characterized by EXAFS, EPR-, UV\\/Vis-spectroscopy, isoelectric focusing, and MALDI-MS and have been shown to contain a dinuclear copper center. Both are monomers with a molecular mass of 39 kDa and 40 kDa, respectively. Substrate specificity and NH2-terminal sequences have been

Christoph Eicken; Frank Zippel; Klaudia Büldt-Karentzopoulos; Bernt Krebs

1998-01-01

32

[Polymorphisms of catechol-O-methyltransferase and monoamine oxidase B genes among Chinese patients with Parkinson's disease].  

PubMed

OBJECTIVE To study polymorphisms of catechol-O-methyltransferase (COMT) and monoamine oxidase B (MAO-B) genes among Chinese patients with Parkinson's disease. METHODS Genotypes of the COMT and MAO-B genes of 1408 patients with Parkinson's disease was sequenced using Sanger method. And these patients were recruited by Chinese Parkinson Study Group from 29 research centers throughout the country. RESULTS The genotypic frequencies of COMT rs4680 AA, AG, GG were 8.9%, 42.0% and 49.1%. Those of rs4818 CC, CG, GG were 42.5%, 45.6% and 11.9%, respectively. The genotype frequencies of MAO-B rs1799836 A/AA, AG, G/GG were 74.4%, 14.1% and 11.5%, respectively. The haplotype formed by COMT rs4680 (GG) and MAO-B rs1799836 (A/AA) genotype has a frequency of 36.86%. CONCLUSION Polymorphisms of COMT and MAO-B genes has a unique characteristics among Chinese patients with Parkinson's disease. They may be related with differences in drug response in such patients. PMID:25636089

Hao, Hongying; Shao, Ming; An, Jing; Chen, Chushuang; Feng, Xiuli; Xie, Shu; Gu, Zhuqin; Chen, Biao

2015-02-10

33

Functional Analysis of Fructosyl-Amino Acid Oxidases of Aspergillus oryzae  

PubMed Central

Three active fractions of fructosyl-amino acid oxidase (FAOD-Ao1, -Ao2a, and -Ao2b) were isolated from Aspergillus oryzae strain RIB40. N-terminal and internal amino acid sequences of FAOD-Ao2a corresponded to those of FAOD-Ao2b, suggesting that these two isozymes were derived from the same protein. FAOD-Ao1 and -Ao2 were different in substrate specificity and subunit assembly; FAOD-Ao2 was active toward N?-fructosyl N?-Z-lysine and fructosyl valine (Fru-Val), whereas FAOD-Ao1 was not active toward Fru-Val. The genes encoding the FAOD isozymes (i.e., FAOAo1 and FAOAo2) were cloned by PCR with an FAOD-specific primer set. The deduced amino acid sequences revealed that FAOD-Ao1 was 50% identical to FAOD-Ao2, and each isozyme had a peroxisome-targeting signal-1, indicating their localization in peroxisomes. The genes was expressed in Escherichia coli and rFaoAo2 showed the same characteristics as FAOD-Ao2, whereas rFaoAo1 was not active. FAOAo2 disruptant was obtained by using ptrA as a selective marker. Wild-type strain grew on the medium containing Fru-Val as the sole carbon and nitrogen sources, but strain ?faoAo2 did not grow. Addition of glucose or (NH4)2SO4 to the Fru-Val medium did not affect the assimilation of Fru-Val by wild-type, indicating glucose and ammonium repressions did not occur in the expression of the FAOAo2 gene. Furthermore, conidia of the wild-type strain did not germinate on the medium containing Fru-Val and NaNO2 as the sole carbon and nitrogen sources, respectively, suggesting that Fru-Val may also repress gene expression of nitrite reductase. These results indicated that FAOD is needed for utilization of fructosyl-amino acids as nitrogen sources in A. oryzae. PMID:15466528

Akazawa, Shin-ichi; Karino, Tetsuya; Yoshida, Nobuyuki; Katsuragi, Tohoru; Tani, Yoshiki

2004-01-01

34

Determination of catechin in green tea using a catechol oxidase biomimetic sensor  

Microsoft Academic Search

Um sensor biomimético catecol oxidase, baseado em um novo complexo cobre(II) foi desenvolvido para determinaçăo de catequina em chá verde e os resultados comparados com os obtidos por eletroforese capilar. O complexo dinuclear de cobre(II) (Cu 2 (HL)(ľ-CH 3 COO)) (ClO 4 ), contendo o ligante N,N-(bis-(2-piridilmetil))-N',N'-((2-hidroxibenzil)(2-hidroxi-3,5- di-tert-butilbenzil))-1,3-propanodiamino-2-ol (H 3 L), foi sintetizado e caracterizado por IV, 1 H RMN

Suellen C. Fernandes; Renata El-Hage; Ademir Neves; Gustavo Amadeu Micke; Iolanda C. Vieira

2008-01-01

35

Isolation and characterization of a micromycete, a producer of neutral catechol oxidases, from tropical soils with elevated dioxine content  

Microsoft Academic Search

—Samples of South Vietnamese soils intensely treated with Agent Orange defoliant were tested for the presence of fungi and\\u000a actinomycetes with an elevated phenol oxidase activity. As a result, a fast-growing nonsporulating strain producing neutral\\u000a phenol oxidases was isolated and identified asMycelia sterilia INBI2-26. The strain formed extracellular phenol oxidases during surface growth on a liquid medium in the presence

L. G. Vasil’chenko; O. V. Koroleva; E. V. Stepanova; E. O. Landesman; M. L. Rabinovich

2000-01-01

36

Heterologous production of Rhizopus oryzae lipase in Pichia pastoris using the alcohol oxidase and formaldehyde dehydrogenase promoters in batch and fed-batch cultures  

Microsoft Academic Search

A Rhizopus oryzae lipase (ROL) has been expressed in Pichia pastoris as a reporter gene using two different regulated promoters. Both phenotypes, Muts and Mut+, have been used for the expression under the control of alcohol oxidase 1 promoter (PAOX1). Moreover, the new formaldehyde dehydrogenase 1 promoter (PFLD1) has been tested. PFLD1 allows the design of methanol-free culture strategies, being

Oriol Cos; David Resina; Pau Ferrer; José Luis Montesinos; Francisco Valero

2005-01-01

37

Production and characterisation of AoSOX2 from Aspergillus oryzae, a novel flavin-dependent sulfhydryl oxidase with good pH and temperature stability.  

PubMed

Sulfhydryl oxidases have found application in the improvement of both dairy and baking products due to their ability to oxidise thiol groups in small molecules and cysteine residues in proteins. A genome mining study of the available fungal genomes had previously been performed by our group in order to identify novel sulfhydryl oxidases suitable for industrial applications and a representative enzyme was produced, AoSOX1 from Aspergillus oryzae (Faccio et al. BMC Biochem 11:31, 2010). As a result of the study, a second gene coding for a potentially secreted sulfhydryl oxidase, AoSOX2, was identified in the genome of A. oryzae. The protein AoSOX2 was heterologously expressed in Trichoderma reesei and characterised with regard to both biochemical properties as well as preliminary structural analysis. AoSOX2 showed activity on dithiothreitol and glutathione, and to a lesser extent on D/L-cysteine and beta-mercaptoethanol. AoSOX2 was a homodimeric flavin-dependent protein of approximately 78 kDa (monomer 42412 Da) and its secondary structure presents alpha-helical elements. A. oryzae AoSOX2 showed a significant stability to pH and temperature. PMID:21327412

Faccio, Greta; Kruus, Kristiina; Buchert, Johanna; Saloheimo, Markku

2011-05-01

38

Gonadectomy and Hormone Replacement Exert Region- and Enzyme Isoform-Specific Effects on Monoamine Oxidase and Catechol-O-Methyltransferase Activity in Prefrontal Cortex and Neostriatum of Adult Male Rats  

PubMed Central

Sex differences and gonadal hormone influences are well known for diverse aspects of forebrain amine and indolamine neurotransmitter systems, the cognitive and affective functions they govern and their malfunction in mental illness. This study explored whether hormone regulation/dysregulation of these systems could be related to gonadal steroid effects on catechol-O-methyltransferase and monoamine oxidase which are principal enzymatic controllers of forebrain dopamine, serotonin and norepinephrine levels. Driven by male over female differences in cortical enzyme activities, by male-specific associations between monoamine oxidase and catechol-O-methyltransferase gene polymorphisms and cognitive and dysfunction in disease and by male-specific consequences of gene knockouts in mice, the question of hormone sensitivity was addressed here using a male rat model where prefrontal dopamine levels and related behaviors are also known to be affected. Specifically, quantitative O-methylation and oxidative deamination assays were used to compare the activities of catechol-O-methyltransferase's soluble and membrane-bound isoforms and of monoamine oxidase's A and B isoforms in the pregenual medial prefrontal cortex and dorsal striatum of male rats that were sham operated, gonadectomized or gonadectomized and supplemented with testosterone propionate or with estradiol for 28 days. These studies revealed significant effects of hormone replacement but not gonadectomy on the soluble but not the membrane-bound isorfom of catechol-O-methyltransferase in both striatum and cortex. A significant, cortex-specific testosterone—but not estradiol—attenuated effect (increase) of gonadectomy on monoamine oxidase's A but not B isoform was also observed. Although none of these actions suggest potential roles in the reguation/dysregulation of prefrontal dopamine, the suppressive effects of testosterone on cortical monoamine oxidase-A that were observed could have bearing on the increased incidence of cognitive deficits and symptoms of depression and anxiety that are repeatedly observed in males in conditions of hypogonadalism related to aging, other biological factors or in prostate cancer where androgen deprivation is used as a neoadjuvant treatment. PMID:19909795

Meyers, B.; D'Agostino, A.; Walker, J.; Kritzer, M. F.

2010-01-01

39

Tyrosinase Models. Synthesis, Structure, Catechol Oxidase Activity, and Phenol Monooxygenase Activity of a Dinuclear Copper Complex Derived from a Triamino Pentabenzimidazole Ligand.  

PubMed

The dicopper(II) complex with the ligand N,N,N',N',N"-pentakis[(1-methyl-2-benzimidazolyl)methyl]dipropylenetriamine (LB5) has been synthesized and structurally characterized. The small size and the quality of the single crystal required that data be collected using synchrotron radiation at 276 K. [Cu(2)(LB5)(H(2)O)(2)][ClO(4)](4): platelet shaped, P&onemacr;, a = 11.028 Ĺ, b = 17.915 Ĺ, c = 20.745 Ĺ, alpha = 107.44 degrees, beta = 101.56 degrees, gamma = 104.89 degrees, V = 3603.7 Ĺ(3), Z = 2; number of unique data, I >/= 2sigma(I) = 3447; number of refined parameters = 428; R = 0.12. The ligand binds the two coppers nonsymmetrically; Cu1 is coordinated through five N donors and Cu2 through the remaining three N donors, while two water molecules complete the coordination sphere. Cu1 has distorted TBP geometry, while Cu2 has distorted SP geometry. Voltammetric experiments show quasireversible reductions at the two copper centers, with redox potential higher for the CuN(3) center (0.40 V) and lower for the CuN(5) center (0.17 V). The complex binds azide in the terminal mode at the CuN(3) center with affinity lower than that exhibited by related dinuclear polyaminobenzimidazole complexes where this ligand is bound in the bridging mode. The catechol oxidase activity of [Cu(2)(LB5)](4+) has been examined in comparison with that exhibited by [Cu(2)(L-55)](4+) (L-55 = alpha,alpha'-bis{bis[(1-methyl-2-benzimidazolyl)methyl]amino}-m-xylene) and [Cu(2)(L-66)](4+) (L-66 = alpha,alpha'-bis{bis[2-(1-methyl-2-benzimidazolyl)ethyl]amino}-m-xylene) by studying the catalytic oxidation of 3,5-di-tert-butylcatechol in methanol/aqueous buffer pH 5.1. Kinetic experiments show that [Cu(2)(L-55)](4+) is the most efficient catalyst (rate constant 140 M(-1) s(-1)), followed by [Cu(2)(LB5)](4+) (60 M(-1) s(-1)), in this oxidation, while [Cu(2)(L-66)](4+) undergoes an extremely fast stoichiometric phase followed by a slow and substrate-concentration-independent catalytic phase. The catalytic activity of [Cu(2)(L-66)](4+), however, is strongly promoted by hydrogen peroxide, because this oxidant allows a fast reoxidation of the dicopper(I) complex during turnover. The activity of [Cu(2)(LB5)](4+) is also promoted by hydrogen peroxide, while that of [Cu(2)(L-55)](4+) is little affected. The phenol monooxygenase activity of [Cu(2)(LB5)](2+) has been compared with that of [Cu(2)(L-55)](2+) and [Cu(2)(L-66)](2+) by studying the ortho hydroxylation of methyl 4-hydroxybenzoate to give methyl 3,4-dihydroxybenzoate. The LB5 complex is much more selective than the other complexes since its reaction produces only catechol, while the main product obtained with the other complexes is an addition product containing a phenol residue condensed at ring position 2 of the catechol. PMID:11670307

Monzani, Enrico; Quinti, Luisa; Perotti, Angelo; Casella, Luigi; Gullotti, Michele; Randaccio, Lucio; Geremia, Silvano; Nardin, Giorgio; Faleschini, Paolo; Tabbě, Giovanni

1998-02-01

40

Relation between the catalytic efficiency of the synthetic analogues of catechol oxidase with their electrochemical property in the free state and substrate-bound state.  

PubMed

A library of 15 dicopper complexes as synthetic analogues of catechol oxidase has been synthesized with the aim to determine the relationship between the electrochemical behavior of the dicopper(II) species in the absence as well as in the presence of 3,5-di-tert-butylcatechol (3,5-DTBC) as model substrate and the catalytic activity, kcat, in DMSO medium. The complexes have been characterized by routine physicochemical techniques as well as by X-ray single-crystal structure analysis in some cases. Fifteen "end-off" compartmental ligands have been designed as 1 + 2 Schiff-base condensation product of 2,6-diformyl-4-R-phenol (R = Me, (t)Bu, and Cl) and five different amines, N-(2-aminoethyl)piperazine, N-(2-aminoethyl)pyrrolidine, N-(2-aminoethyl)morpholine, N-(3-aminopropyl)morpholine, and N-(2-aminoethyl)piperidine. Interestingly, in case of the combination of 2,6-diformyl-4-methylphenol and N-(2-aminoethyl)morpholine/N-(3-aminopropyl)morpholine/N-(2-aminoethyl)piperidine 1 + 1 condensation becomes the reality and the ligands are denoted as L2(1-3). On reaction of copper(II) nitrate with L2(1-3) in situ complexes 3, 12, and 13 are formed having general formula Cu2(L2(1-3))2(NO3)2. The remaining 12 ligands obtained as 1 + 2 condensation products are denoted as L1(1-12), which produce complexes having general formula Cu2(L1(1-12))(NO3)2. Catecholase activity of all 15 complexes has been investigated in DMSO medium using 3,5-DTBC as model substrate. Treatment on the basis of Michaelis-Menten model has been applied for kinetic study, and thereby turnover number, kcat, values have been evaluated. Cyclic voltametric (CV) and differential pulse voltametric (DPV) studies of the complexes in the presence as well as in the absence of 3,5-DTBC have been thoroughly investigated in DMSO medium. From those studies it is evident that oxidation of 3,5-DTBC catalyzed by dicopper(II) complexes proceed via two steps: first, semibenzoquinone followed by benzoquinone with concomitant reduction of Cu(II) to Cu(I). Our study reveals that apparently there is nearly no linear relationship between kcat and E° values of the complexes. However, a detailed density functional theory (DFT) calculation sheds light on this subject. A very good correlation prevails in terms of the energetics associated with the Cu(II) to Cu(I) reduction process and kcat values, as revealed from the combined theoretical and experimental approach. PMID:25072328

Chakraborty, Prateeti; Adhikary, Jaydeep; Ghosh, Bipinbihari; Sanyal, Ria; Chattopadhyay, Shyamal Kumar; Bauzá, Antonio; Frontera, Antonio; Zangrando, Ennio; Das, Debasis

2014-08-18

41

Molecular Structure of Catechol  

NSDL National Science Digital Library

Catechol is a colorless, crystalline solid with a phenolic, faint odor and a sweet-bitter taste. It is soluble in alcohol, ether and acetate. Catechol is used as an antioxidant, astringent, antiseptic, antifungal preservative for treating seed potato pieces, photographic developer, in fur dyes manufacture and as an intermediate in lubricanting oils. It is also used in polymerization inhibitors and in pharmaceuticals. Catechol is prepared by treating salicylaldehyde with hydrogen peroxide, or from its monomethyl ether by treatment with hydrobromic acid. Originally, catechol was isolated from a type of mimosa tree. Catechol has been found in food, drinking water and cigarette smoke. Skin contact with catechol causes eczema in humans.

2004-11-09

42

Identification of catechol as a new marker for detecting propolis adulteration.  

PubMed

Adulteration of propolis with poplar extract is a serious issue in the bee products market. The aim of this study was to identify marker compounds in adulterated propolis, and examine the transformation of chemical components from poplar buds to propolis. The chemical profiles of poplar extracts and propolis were compared, and a new marker compound, catechol, was isolated and identified from the extracts of poplar buds. The polyphenol oxidase, catechol oxidase, responsible for catalyzing oxidation of catechol was detected in poplar buds and propolis. The results indicate catechol can be used as a marker to detect propolis adulterated with poplar extract. PMID:25025150

Huang, Shuai; Zhang, Cui-Ping; Li, George Q; Sun, Yue-Yi; Wang, Kai; Hu, Fu-Liang

2014-01-01

43

Polyphenol oxidases and phenolics in relation to resistance against cucumber scab in Cucumis Sativus I. Fungal and host polyphenol oxidases  

Microsoft Academic Search

In culture filtrates ofCladosporium cucumerinum, the fungus causing cucumber scab, a constitutive, exocellular catechol oxidase was found; moreover, dihydroxy-phenylalanine and chlorogenic acid oxidases were produced. Catechol oxidase was detected in noticeable activity as soon as the pH of the culture medium had reached a value of 6.0, or if the medium was adjusted to this pH before sterilizing. The Michaelis

A. Fuchs

1965-01-01

44

New functional models for catechol oxidases  

Microsoft Academic Search

The new dinuclear copper(II) complexes [Cu2(L1)(?-OAc)](ClO4)2ˇCH3CN (1), [Cu2(L2)(CH3CN)2](ClO4)4ˇC2H5OH (2), [Cu2(L3)2(CH3CN)2](PF6)2 (3) and [Cu2(L4)2](PF6)2ˇ2CH2Cl2 (4) were prepared with the ligands N,N,N?,N?-tetrakis( (N-2-hydroxyethyl)-2-benzimidazolylmethyl)-2-hydroxy-1,3-diaminopropane HL1, N,N,N?,N?-tetrakis (2-methylimidazolyl)-2-hydroxy-1,3-diaminopropane HL2, (2-pyridylmethyl)(1-hydroxypropyl)amine HL3 and (2-hydroxybenzyl)(N,N-dimethylpropyl)amine HL4. All complexes were characterized by X-ray structure determination, revealing dinuclear cations and perchlorate or hexafluorophosphate counter ions. In the complex cations the two copper(II) atoms show different coordination spheres with

Pavel Gentschev; Niclas Möller; Bernt Krebs

2000-01-01

45

Catecholamines oxidation by xanthine oxidase.  

PubMed

Dopamine and structurally related catecholamines in the presence of hydrogen peroxide are oxidized in vitro by xanthine oxidase producing the corresponding melanin pigments. The kinetic parameters of the reaction, measured as aminochrome formation, have been calculated. The rate of peroxidation depends on enzyme and hydrogen peroxide concentration. The optimum pH for the peroxidative activity of the enzyme is around 8.5. Activation of the peroxidative reaction is also elicited by catechol compounds through a redox cycle mechanism. Implications about the possible biochemical relevance of xanthine oxidase activity on catecholamines oxidation are discussed. PMID:9101714

Foppoli, C; Coccia, R; Cini, C; Rosei, M A

1997-03-15

46

The Three Catecholics Benserazide, Catechol and Pyrogallol are GPR35 Agonists  

PubMed Central

Nearly 1% of all clinically used drugs are catecholics, a family of catechol-containing compounds. Using label-free dynamic mass redistribution and Tango ?-arrestin translocation assays, we show that several catecholics, including benserazide, catechol, 3-methoxycatechol, pyrogallol, (+)-taxifolin and fenoldopam, display agonistic activity against GPR35. PMID:24276120

Deng, Huayun; Fang, Ye

2013-01-01

47

The bacterial degradation of catechol  

PubMed Central

1. Two strains of Pseudomonas were grown with phenol and used to prepare cell extracts that metabolized catechol with the transient formation of 2-hydroxymuconic semialdehyde. 2. One of these preparations catalysed the conversion of 1mol. of catechol into 1mol. each of formate and 4-hydroxy-2-oxovalerate. 3. A method for the determination of 4-hydroxy-2-oxovalerate is described, together with some properties of this compound and its 2,4-dinitrophenylhydrazone. 4. Another partially purified cell extract converted 1mol. of 4-hydroxy-2-oxovalerate, formed enzymically from catechol, into 1mol. each of acetaldehyde and pyruvate. This aldolase had a pH optimum of about 8ˇ8, was stimulated by Mg2+ ions and appeared to attack only one enantiomer of synthetic 4-hydroxy-2-oxovalerate. PMID:14340096

Dagley, S.; Gibson, D. T.

1965-01-01

48

Beyond brown: polyphenol oxidases as enzymes of plant specialized metabolism  

PubMed Central

Most cloned and/or characterized plant polyphenol oxidases (PPOs) have catechol oxidase activity (i.e., they oxidize o-diphenols to o-quinones) and are localized or predicted to be localized to plastids. As a class, they have broad substrate specificity and are associated with browning of produce and other plant materials. Because PPOs are often induced by wounding or pathogen attack, they are most generally believed to play important roles in plant defense responses. However, a few well-characterized PPOs appear to have very specific roles in the biosynthesis of specialized metabolites via both tyrosinase (monophenol oxidase) and catechol oxidase activities. Here we detail a few examples of these and explore the possibility that there may be many more “biosynthetic” PPOs.

Sullivan, Michael L.

2015-01-01

49

Spinach Thylakoid Polyphenol Oxidase 1  

PubMed Central

Polyphenol oxidase activity (E.C. 1.14.18.1) has been found in two enzyme species isolated from thylakoid membranes of spinach chloroplasts. The proteins were released from the membrane by sonication and purified >900-fold by ammonium sulfate precipitation, gel filtration, and ion-exchange chromatography. The enzymes appear to be the tetramer and monomer of a subunit with a molecular weight of 42,500 as determined by lithium dodecyl sulfate gel electrophoresis. The higher molecular weight enzyme is the predominant form in freshly isolated preparations but on aging or further purification, the amount of lower molecular weight enzyme increases at the expense of the higher. Sonication releases polyphenol oxidase from the membrane largely in the latent state. C18 fatty acids, especially linolenic acid, are potent activators of the enzymic activity. In the absence of added fatty acids, the isolated enzyme spontaneously, but slowly, activates with time. Purified polyphenol oxidase utilizes o-diphenols as substrates and shows no detectable levels of monophenol or p-diphenol oxidase activities. The Km values for 3,4-dihydroxyphenylalanine and O2 are 6.5 and 0.065 millimolar, respectively. Suitable substrates include chlorogenic acid, catechol, caffeic acid, pyrogallol, and dopamine; however, the enzyme is substrate-inhibited by the last four at concentrations near their Km A large seasonal variation in polyphenol oxidase activity may result from a decrease in enzyme content rather than inhibition of the enzyme present. Images PMID:16661805

Golbeck, John H.; Cammarata, Kirk V.

1981-01-01

50

Structural and spectroscopic studies of a model for catechol oxidase  

Microsoft Academic Search

A binuclear copper complex, [Cu2(BPMP)(OAc)2][ClO4]ˇH2O, has been prepared using the binucleating ligand 2,6-bis[bis(pyridin-2-ylmethylamino)methyl]-4-methylphenol (H-BPMP). The\\u000a X-ray crystal structure reveals the copper centers to have a five-coordinate square pyramidal geometry, with the acetate ligands\\u000a bound terminally. The bridging phenolate occupies the apical position of the square-based pyramids and magnetic susceptibility,\\u000a electron paramagnetic resonance (EPR) and variable-temperature variable-field magnetic circular dichroism (MCD)

Sarah J. Smith; Christopher J. Noble; Randahl C. Palmer; Graeme R. Hanson; Gerhard Schenk; Lawrence R. Gahan; Mark J. Riley

2008-01-01

51

Immobilization of tyrosinase and alcohol oxidase in conducting copolymers of thiophene functionalized poly(vinyl alcohol) with pyrrole  

Microsoft Academic Search

Immobilization of tyrosinase and alcohol oxidase is achieved in the copolymer of pyrrole with vinyl alcohol with thiophene side groups (PVATh-co-PPy) which is a newly synthesized conducting polymer. PVATh-co-PPy\\/alcohol oxidase and PVATh-co-PPy\\/tyrosinase electrodes are constructed by the entrapment of enzyme in conducting copolymer matrix during electrochemical copolymerization. For tyrosinase and alcohol oxidase enzymes, catechol and ethanol are used as the

Huseyin Bekir Yildiz; Ertugrul Sahmetlioglu; Ayse Elif Boyukbayram; Levent Toppare; Yusuf Yagci

2007-01-01

52

Evidence for saturation of catechol-0-methyltransferase by low concentrations of noradrenaline in perfused lungs of rats  

Microsoft Academic Search

Previous studies on the pulmonary removal and metabolism of catecholamines in rat lungs have shown that, when the lungs are perfused with a low concentration (1 nmol\\/1) of noradrenaline, the amine is metabolized by catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO), but is predominantly O-methylated, and the activities of COMT and MAO are 0.357 min–1 and 0.186 min-1, respectively. The aim

Lesley J. Bryan-Lluka

1995-01-01

53

Oxidase Test Protocol  

NSDL National Science Digital Library

The oxidase test is used to detect the presence of the enzyme cytochrome oxidase in microorganisms.  While used as a taxonomic tool for many microorganisms, the test was established initially to differentiate Neisseria spp. (oxidase positive) from Acinetobacter (oxidase negative) and Pseudomonas spp. (oxidase positive) from the Enterobacteriaceae (oxidase negative).

American Society For Microbiology;

2010-11-11

54

Purification and some properties of polyphenol oxidase of longan fruit  

Microsoft Academic Search

Polyphenol oxidase (PPO) was isolated from longan (Dimocarpus longan Lour.) fruit peel, with a 46-fold purification of PPO by ammonium sulfate, Sephadex G-200 and Phenyl Sepharose being achieved. Pyrogallol, 4-methylcatechol, and catechol were good substrates for the enzyme, and activity with chlorogenic acid, p-cresol, resorcinol, or tyrosine was not observed. The optimal pH for PPO activity was 6.5 with 4-methylcatechol.

Yue-Ming Jiang

1999-01-01

55

Xylem occlusion in bouvardia flowers: evidence for a role of peroxidase and cathechol oxidase  

Microsoft Academic Search

During vase life, Bouvardia flowers show rapid leaf wilting, especially if they are stored dry prior to placement in water. Wilting is due to a blockage in the basal stem end. We investigated the possible role of peroxidase and catechol oxidase in the blockage in cv. van Zijverden flowers, which were placed, for 5 h at 20°C, in an aqueous

Nicolas Vaslier; Wouter G. van Doorn

2003-01-01

56

Biochemical characteristics and thermal inhibition kinetics of polyphenol oxidase extracted from Thompson seedless grape  

Technology Transfer Automated Retrieval System (TEKTRAN)

Polyphenol oxidase (PPO) was isolated from Thompson seedless grape (Vitis vinifera 'Thompson Seedless') and its biochemical characteristics were studied. Optimum pH and temperature for grape PPO activity were pH 6.0 and 25 degrees C with 10 mM catechol as substrate. The enzyme was heat-stable betwee...

57

Analyzing autophagy in Magnaporthe oryzae.  

PubMed

Magnaporthe oryzae is an important plant pathogenic fungus that greatly threatens the world's food security. Both genome-wide and individual gene studies have shown that the pathogenicity of the fungus is severely dependent on the intracellular autophagy process during appressoria development. This protocol discusses a systematic methodology to discover and monitor autophagy-related (ATG) genes in M. oryzae. PMID:21317549

Xu, Fei; Liu, Xiao-Hong; Zhuang, Fei-Long; Zhu, Jun; Lin, Fu-Cheng

2011-05-01

58

Diphenol activation of the monophenolase and diphenolase activities of field bean (Dolichos lablab) polyphenol oxidase.  

PubMed

This paper reports a study on the hydroxylation of ferulic acid and tyrosine by field bean (Dolichos lablab) polyphenol oxidase, a reaction that does not take place without the addition of catechol. A lag period similar to the characteristic lag of tyrosinase activity was observed, the length of which decreased with increasing catechol concentration and increased with increasing ferulic acid concentration. The activation constant K(a) of catechol for ferulic acid hydroxylation reaction was 5 mM. The kinetic parameters of field bean polyphenol oxidase toward ferulic acid and tyrosine were evaluated in the presence of catechol. 4-Methyl catechol, L-dihydroxyphenylalanine, pyrogallol, and 2,3,4-trihydroxybenzoic acid, substrates with high binding affinity to field bean polyphenol oxidase, could stimulate this hydroxylation reaction. In contrast, diphenols such as protocatechuic acid, gallic acid, chlorogenic acid, and caffeic acid, which were not substrates for the oxidation reaction, were unable to bring about this activation. It is most likely that only o-diphenols that are substrates for the diphenolase serve as cosubstrates by donating electrons at the active site for the monophenolase activity. The reaction mechanism for this activation is consistent with that proposed for tyrosinase (Sanchez-Ferrer, A.; Rodriguez-Lopez, J. N.; Garcia-Canovas, F.; Garcia-Carmona, F. Biochim. Biophys. Acta 1995, 1247, 1-11). The presence of o-diphenols, viz. catechol, L-dihydroxyphenylalanine, and 4-methyl catechol, is also necessary for the oxidation of the diphenols, caffeic acid, and catechin to their quinones by the field bean polyphenol oxidase. This oxidation reaction occurs immediately with no lag period and does not occur without the addition of diphenol. The kinetic parameters for caffeic acid (K(m) = 0.08 mM, V(max) = 32440 u/mg) in the presence of catechol and the activation constant K(a) of catechol (4.6 mM) for this reaction were enumerated. The absence of a lag period for this reaction indicates that the diphenol mechanism of diphenolase activation differs from the way in which the same o-diphenols activate the monophenolase activity. PMID:11879044

Gowda, Lalitha R; Paul, Beena

2002-03-13

59

PEM Anchorage on Titanium Using Catechol Grafting  

PubMed Central

Background This study deals with the anchorage of polyelectrolyte films onto titanium surfaces via a cathecol-based linker for biomedical applications. Methodology The following study uses a molecule functionalized with a catechol and a carboxylic acid: 3-(3,4-dihydroxyphenyl)propanoic acid. This molecule is anchored to the TiO2 substrate via the catechol while the carboxylic acid reacts with polymers bearing amine groups. By providing a film anchorage of chemisorption type, it makes possible to deposit polyelectrolytes on the surface of titanium. Principal Findings Infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), contact angle and atomic force microscopy (AFM) measurements show that the different steps of grafting have been successfully performed. Conclusions This method based on catechol anchorage of polyelectrolytes open a window towards large possibilities of clinical applications. PMID:23226262

Marie, Hélčne; Barrere, Amélie; Schoentstein, Frédérique; Chavanne, Marie-Hélčne; Grosgogeat, Brigitte; Mora, Laurence

2012-01-01

60

The role of catechol-O-methyltransferase in catechol-enhanced erythroid differentiation of K562 cells  

SciTech Connect

Catechol is widely used in pharmaceutical and chemical industries. Catechol is also one of phenolic metabolites of benzene in vivo. Our previous study showed that catechol improved erythroid differentiation potency of K562 cells, which was associated with decreased DNA methylation in erythroid specific genes. Catechol is a substrate for the catechol-O-methyltransferase (COMT)-mediated methylation. In the present study, the role of COMT in catechol-enhanced erythroid differentiation of K562 cells was investigated. Benzidine staining showed that exposure to catechol enhanced hemin-induced hemoglobin accumulation and induced mRNA expression of erythroid specific genes in K562 cells. Treatment with catechol caused a time- and concentration-dependent increase in guaiacol concentration in the medium of cultured K562 cells. When COMT expression was knocked down by COMT shRNA expression in K562 cells, the production of guaiacol significantly reduced, and the sensitivity of K562 cells to cytotoxicity of catechol significantly increased. Knockdown of COMT expression by COMT shRNA expression also eliminated catechol-enhanced erythroid differentiation of K562 cells. In addition, the pre-treatment with methyl donor S-adenosyl-L-methionine or its demethylated product S-adenosyl-L-homocysteine induced a significant increase in hemin-induced Hb synthesis in K562 cells and the mRNA expression of erythroid specific genes. These findings indicated that O-methylation catalyzed by COMT acted as detoxication of catechol and involved in catechol-enhanced erythroid differentiation of K562 cells, and the production of S-adenosyl-L-homocysteine partly explained catechol-enhanced erythroid differentiation. - Highlights: • Catechol enhanced hemin-induced hemoglobin accumulation. • COMT-catalyzed methylation acted as detoxication of catechol. • COMT involved in catechol-enhanced erythroid differentiation.

Suriguga,; Li, Xiao-Fei; Li, Yang; Yu, Chun-Hong; Li, Yi-Ran; Yi, Zong-Chun, E-mail: yizc@buaa.edu.cn

2013-12-15

61

Catechol Formation and Melanization by Na+ -Dependent Azotobacter chroococcum: a Protective Mechanism for Aeroadaptation?  

PubMed Central

Aeroadaptive microaerophilic Azotobacter chroococcum 184 produced a cell-associated black pigment when grown at high aeration rates under nitrogen-fixing conditions. This pigment was shown to be a catechol melanin. Polyphenol oxidase activity was detected in cell extracts of cells grown for 72 h. Melanin formation was optimal in the later stages of growth, and there was no correlation between nitrogenase activity and melanization. Nitrogenase activity in strain 184 was optimal at 10% O2, and melanin formation was suppressed by O2 limitation. In the presence of charcoal, an adsorbent of toxic oxygen intermediates, and benzoic acid, a scavenger of hydroxyl radicals, melanization was inhibited. However, in the presence of copper, the intensity of pigment color increased and melanization was accelerated. Copper also eliminated catalase and peroxidase activities of the organism but still permitted aerobic growth. In the presence of low levels of iron, melanization was accelerated under high aeration rates, and under low rates of aeration, melanization was observed only at higher levels of iron. Hydroxamate-siderophore production was detectable in the presence of soluble iron under high rates of aeration but was repressed by the same levels of iron under low aeration rates. Unlike melanization and hydroxamate formation, catechol formation was observed under both low and high rates of aeration under nitrogen-fixing conditions. Catechol formation and melanization were repressed by 14 mM NH4+, at which level nitrogenase activity was also repressed. Copper reversed the repressive effect of NH4+. A role for catechol formation and melanization in aeroadaptation is proposed. PMID:16347974

Shivprasad, Shailaja; Page, William J.

1989-01-01

62

Herbicidal potential of catechol as an allelochemical.  

PubMed

Catechol is an allelochemical which belongs to phenolic compounds synthesized in plants. Its herbicidal effects on weed species; field poppy (Papaver rhoeas), creeping thistle (Cirsium arvense), henbit (Lamium amplexicaule) and wild mustard (Sinapis arvensis) were investigated using wheat (Triticum vulgare) and barley (Hordeum vulgare) species as control plants. In comparison to 2,4-D (a common synthetic herbicide), 13.64 mM of catechol have been found to have a strong herbicidal effect, as effective as 2,4-D on field poppy weed by killing it, and a suppressive herbicidal effect on the other weeds by inhibiting their growth significantly. Concerning all the weeds, in general, elongation of the shoot was affected more negatively than that of the root. Fresh weights of the weeds were decreased by catechol significantly only in field poppy but not in other weeds. The study reveals that catechol is a potent inhibitor of growth of the weeds and therefore it can be evaluated as a herbicide for future weed management strategies. PMID:16610220

Topal, Süleyman; Kocaçali?kan, Ismail; Arslan, Orhan

2006-01-01

63

Catechol-o-methyltransferase inhibitors in Parkinson's disease.  

PubMed

Inhibitors of catechol-O-methyltransferase (COMT) are commonly used as an adjunct to levodopa in patients with Parkinson's disease (PD) for the amelioration of wearing-off symptoms. This narrative review aims to discuss the role of COMT inhibitors on peripheral levodopa metabolism and continuous brain delivery of levodopa, and to describe their metabolic properties. Oral application of levodopa formulations with a dopa decarboxylase inhibitor (DDI) results in fluctuating levodopa plasma concentrations, predominantly due to the short half-life of levodopa and its slowing of gastric emptying. Following transport across the blood-brain barrier and its metabolic conversion to dopamine, these peripheral 'ups and downs' of levodopa are reflected in fluctuating dopamine levels in the synaptic cleft between presynaptic and postsynaptic dopaminergic neurons of the nigrostriatal system. As a result, pulsatile postsynaptic dopaminergic stimulation takes place and results in the occurrence of motor complications, such as wearing-off and dyskinesia. More continuous plasma behaviour was observed after the combination of levodopa/DDI formulations with COMT inhibitors. These compounds also weaken a levodopa/DDI-related homocysteine increase, as biomarker for an impaired methylation capacity, which is involved in an elevated oxidative stress exposure. These findings favour the concept of chronic levodopa/DDI application with concomitant inhibition of COMT and monoamine oxidase, since deamination of dopamine via this enzyme also generates free radicals. This triple combination is suggested as standard levodopa application in patients with PD who need levodopa, if they will tolerate it. PMID:25559423

Müller, Thomas

2015-02-01

64

Rice ( Oryza) hemoglobins  

PubMed Central

Hemoglobins (Hbs) corresponding to non-symbiotic (nsHb) and truncated (tHb) Hbs have been identified in rice ( Oryza). This review discusses the major findings from the current studies on rice Hbs. At the molecular level, a family of the nshb genes, consisting of hb1, hb2, hb3, hb4 and hb5, and a single copy of the thb gene exist in Oryza sativa var. indica and O. sativa var. japonica, Hb transcripts coexist in rice organs and Hb polypeptides exist in rice embryonic and vegetative organs and in the cytoplasm of differentiating cells. At the structural level, the crystal structure of rice Hb1 has been elucidated, and the structures of the other rice Hbs have been modeled. Kinetic analysis indicated that rice Hb1 and 2, and possibly rice Hb3 and 4, exhibit a very high affinity for O 2, whereas rice Hb5 and tHb possibly exhibit a low to moderate affinity for O 2. Based on the accumulated information on the properties of rice Hbs and data from the analysis of other plant and non-plant Hbs, it is likely that Hbs play a variety of roles in rice organs, including O 2-transport, O 2-sensing, NO-scavenging and redox-signaling. From an evolutionary perspective, an outline for the evolution of rice Hbs is available. Rice nshb and thb genes vertically evolved through different lineages, rice nsHbs evolved into clade I and clade II lineages and rice nshbs and thbs evolved under the effect of neutral selection. This review also reveals lacunae in our ability to completely understand rice Hbs. Primary lacunae are the absence of experimental information about the precise functions of rice Hbs, the properties of modeled rice Hbs and the cis-elements and trans-acting factors that regulate the expression of rice hb genes, and the partial understanding of the evolution of rice Hbs. PMID:25653837

Arredondo-Peter, Raúl; Moran, Jose F.; Sarath, Gautam

2014-01-01

65

Analytical expressions pertaining to the concentration of catechol, o-quinone and current at PPO-modified microcylinder biosensor for diffusion-kinetic model  

Microsoft Academic Search

A theoretical model for electroenzymatic process of a modified microcylinder electrode in which polyphenol oxidase occurs for all values of the concentration of catechol and o-quinone is presented. The model is based on system of reaction–diffusion equations containing a non-linear term related to Michaelis–Menten kinetics of the enzymatic reaction. In this paper, we implement a new analytical technique (He’s variational

A. Eswari; L. Rajendran

2011-01-01

66

Jack of all trades: versatile catechol crosslinking mechanisms.  

PubMed

Catechols play an important role in many natural systems. They are known to readily interact with both organic (e.g., amino acids) and inorganic (e.g., metal ions, metal oxides) compounds, thereby providing a powerful system for protein curing. Catechol crosslinked protein networks, such as sclerotized cuticle and byssal threads of the mussel, have been shown to exhibit excellent mechanical properties. A lot of effort has been devoted to mimicking the natural proteins using synthetic catechol-functionalized polymers. Despite the success in developing catechol-functionalized materials, the crosslinking chemistry of catechols is still a subject of debate. To develop materials with controlled and superior properties, a clear understanding of the crosslinking mechanism of catechols is of vital importance. This review describes the crosslinking pathways of catechol and derivatives in both natural and synthetic systems. We discuss existing pathways of catechol crosslinking and parameters that affect the catechol chemistry in detail. This overview will point towards a rational direction for further investigation of the complicated catechol chemistry. PMID:25231624

Yang, Juan; Cohen Stuart, Martien A; Kamperman, Marleen

2014-12-21

67

Nitroderivatives of catechol: from synthesis to application.  

PubMed

Nitroderivatives of catechol (NDCs) are reviewed with special emphasis on their complexes and applications. Binary, ternary and quaternary NDC complexes with more than 40 elements (aluminum, arsenic, boron, beryllium, calcium, cobalt, copper, iron, gallium, germanium, magnesium, manganese, molybdenum, niobium, rare earth elements, silicon, tin, strontium, technetium, thallium, titanium, uranium, vanadium, tungsten, zinc and zirconium) are discussed and the key characteristics of the developed analytical procedures - tabulated. The bibliography includes 206 references. PMID:24061167

Gavazov, Kiril B

2012-03-01

68

Iron coordination by catechol derivative antioxidants.  

PubMed

Iron complexes of nitrocatechols with different substituent groups [1: -CH = CR2; 2: -CH2-CHR2; 3: -CH = CR'(R")] were synthesized and their effects on iron-induced free radical reactions of biological importance investigated. Catechol and nitrocatechol derivatives effectively inhibited iron-induced lipid peroxide-dependent lipid peroxidation. In the Fenton-like reaction, iron-catechol generated hydroxyl radicals more strongly than did iron citrate, and iron-nitrocatechol derivative 2 generated a small amount of hydroxyl radicals. The iron complexes of derivatives 1 and 3 did not generate hydroxyl radicals. Iron-catechol had the highest ratio of reduction to oxidation rate constants and the second was iron-nitrocatechol 2, suggesting that iron chelated by nitrocatechols 1 and 3 may be most difficult to reduce. To elucidate the structure and physical properties of the iron complexes, UV/vis absorption spectroscopic, ESR and 1H NMR studies were performed in aqueous and DMSO solutions. In aqueous solution at pH 7.4, iron complexes of the nitrocatechol derivatives were high-spin tris(nitrocatecholato)ferrate(III) with a characteristic ligand-to-metal charge transfer absorbance (pi -> d pi). The lambda max of iron-nitrocatechol derivative 2 was shorter than those of iron-nitrocatechol derivatives 1 and 3, suggesting that the reduction potential of iron-nitrocatechol 2 is higher than that of iron-nitrocatechols 1 and 3. Nitrocatechol derivatives with a conjugation structure can sequester the chelated iron more effectively than catechol and the derivative without the conjugation against free radical generation by keeping the iron in the ferric state, probably because of the reduction potentials. PMID:8630099

Kawabata, T; Schepkin, V; Haramaki, N; Phadke, R S; Packer, L

1996-06-14

69

New Porous Crystals of Extended Metal-Catecholates Mohamad Hmadeh,,  

E-print Network

to carboxylate,1 imidazolate,2 other azolates,3 or sulfonate.4 Although catecholate organic units are well. These new crystalline materials, termed metal-catecholates (M-CATs), were characterized by X-ray diffraction techniques (single crystal for Co-CAT-1, and powder for Ni-CAT-1) and high- resolution transmission electron

Yaghi, Omar M.

70

Some kinetic properties of polyphenol oxidase from Thymbra spicata L. var. spicata  

Microsoft Academic Search

Polyphenol oxidase (PPO) of Thymbra (Thymbra spicata L. var. spicata) was isolated by (NH4)2SO4 precipitation and dialysis. A diphenolase from Thymbra plant, active against 4-methylcatechol, catechol and pyrogallol was characterized in detail in terms of pH and temperature optima, stability, kinetic parameters and inhibition behaviour towards some general PPO inhibitors. 4-Methylcatechol was the most suitable substrate, due to the lowest

Serap Do?an; P?nar Turan; Mehmet Do?an

2006-01-01

71

Partial purification and some properties of polyphenol oxidase extracted from litchi fruit pericarp  

Microsoft Academic Search

Litchi (Litchi chinensis Sonn.) fruit peel polyphenol oxidase (PPO) was partially purified 21 fold by ammonium sulfate fractionation and gel filtration. Pyrogallol, catechol, and 4-methylcatechol were good substrates for the enzyme; with no activity observed with chlorogenic acid, p-cresol, resorcinol, or tyrosine. The optimal pH for PPO activity was 7.0 with 4-methylcatechol, with the enzyme being most stable at pH

Jiang Yue-Ming; Giora Zauberman; Yoram Fuchs

1997-01-01

72

DNA integrity of onion root cells under catechol influence.  

PubMed

Catechol is a highly toxic organic pollutant, usually abundant in the waste effluents of industrial processes and agricultural activities. The environmental sources of catechol include pesticides, wood preservatives, tanning lotion, cosmetic creams, dyes, and synthetic intermediates. Genotoxicity of catechol at a concentration range 5?×?10(-1)-5 mM was evaluated by applying random amplified polymorphic DNA (RAPD) and time-lapse DNA laddering tests using onion (Allium cepa) root cells as the assay system. RAPD analysis revealed polymorphisms in the nucleotidic sequence of DNA that reflected the genotoxic potential of catechol to provoke point mutations, or deletions, or chromosomal rearrangements. Time-lapse DNA laddering test provided evidence that catechol provoked DNA necrosis and apoptosis. Acridine orange/ethidium bromide staining could distinguish apoptotic from necrotic cells in root cells of A. cepa. PMID:23307075

Petriccione, Milena; Forte, Valentina; Valente, Diego; Ciniglia, Claudia

2013-07-01

73

Renalase is an ?-NAD(P)H oxidase/anomerase.  

PubMed

Renalase is a protein hormone secreted into the blood by the kidney that is reported to lower blood pressure and slow heart rate. Since its discovery in 2005, renalase has been the subject of conjecture pertaining to its catalytic function. While it has been widely reported that renalase is the third monoamine oxidase (monoamine oxidase C) that oxidizes circulating catecholamines such as epinephrine, there has been no convincing demonstration of this catalysis in vitro. Renalase is a flavoprotein whose structural topology is similar to known oxidases, lysine demethylases, and monooxygenases, but its active site bears no resemblance to that of any known flavoprotein. We have identified the catalytic activity of renalase as an ?-NAD(P)H oxidase/anomerase, whereby low equilibrium concentrations of the ?-anomer of NADPH and NADH initiate rapid reduction of the renalase flavin cofactor. The reduced cofactor then reacts with dioxygen to form hydrogen peroxide and releases nicotinamide dinucleotide product in the ?-form. These processes yield an apparent turnover number (0.5 s(-1) in atmospheric dioxygen) that is at least 2 orders of magnitude more rapid than any reported activity with catechol neurotransmitters. This highly novel activity is the first demonstration of a role for naturally occurring ?-NAD(P)H anomers in mammalian physiology and the first report of a flavoprotein catalyzing an epimerization reaction. PMID:23964689

Beaupre, Brett A; Carmichael, Brenton R; Hoag, Matthew R; Shah, Dhara D; Moran, Graham R

2013-09-18

74

Optimization of glucose oxidase production by Aspergillus niger using genetic- and process-engineering techniques.  

PubMed

Wild-type Aspergillus niger NRRL-3 was transformed with multiple copies of the glucose oxidase structural gene (god). The gene was placed under the control of the gpdA promoter of A. nidulans. For more efficient secretion the alpha-amylase signal peptide from A. oryzae was inserted in front of god. Compared to the wild type, the recombinant strain NRRL-3 (GOD3-18) produced up to four times more extracellular glucose oxidase under identical culture conditions. Addition of yeast extract (2 gl-1) to a mineral salts medium containing only glucose as carbon source increased volumetric and specific extracellular glucose oxidase activities by 130% and 50% respectively. With the same medium composition and inoculum size, volumetric and specific extracellular glucose oxidase activities increased more than ten times in bioreactor cultivations compared to shake-flask cultures. PMID:8590664

Hellmuth, K; Pluschkell, S; Jung, J K; Ruttkowski, E; Rinas, U

1995-11-01

75

Assessment of catechol induction and glucuronidation in rat liver microsomes.  

PubMed

Catechols are substances with a 1,2-dihydroxybenzene group from natural or synthetic origin. The aim of this study was to determine whether catechols (4-methylcatechol, 4-nitrocatechol, 2,3-dihydroxynaphthalene) and the antiparkinsonian drugs, entacapone and tolcapone, at doses 150 to 300 mg/kg/day, for 3 days, are able to enhance their own glucuronidation. The induction potency of catechols on rat liver UDP-glucuronosyltransferases (UGTs) was compared with that of a standard polychlorinated biphenyl (PCB) inducer, Aroclor 1254. The glucuronidation rate of these catechols was enhanced up to 15-fold in the liver microsomes of PCB-treated rats, whereas treatment with catechols had little effect. Entacapone, tolcapone, 4-methylcatechol, catechol, 2,3-dihydroxynaphthalene, and 4-nitrocatechol were glucuronidated in control microsomes at rates ranging from 0.12 for entacapone to 22.0 nmol/min/mg for 4-nitrocatechol. Using 1-naphthol, entacapone, and 1-hydroxypyrene as substrates, a 5-, 8-, and 16-fold induction was detected in the PCB rats, respectively, whereas the catechol-induced activities were 1.1- to 1.5-fold only. Entacapone was glucuronidated more efficiently by PCB microsomes than by control microsomes (Vmax/Km, 0.0125 and 0.0016 ml/min/mg protein, respectively). Similar kinetic results were obtained for 1-hydroxypyrene. The Eadie-Hofstee plots suggested the contribution of multiple UGTs for the glucuronidation of 1-hydroxypyrene (Km1, Km2, Km3 = 0.8, 9.7, and 63 microM, and Vmax1, Vmax2, Vmax3 = 11, 24, and 55 nmol/min/mg, respectively), whereas only one UGT could be implicated in the glucuronidation of entacapone (Km = 130 microM, Vmax = 1.6 nmol/min/mg). In conclusion, catechols are poor inducers of their own glucuronidation supported by several UGT isoforms. Their administration is unlikely to affect the glucuronidation of other drugs administered concomitantly. PMID:15371300

Elovaara, Eivor; Mikkola, Jouni; Luukkanen, Leena; Antonio, Laurence; Fournel-Gigleux, Sylvie; Burchell, Brian; Magdalou, Jacques; Taskinen, Jyrki

2004-12-01

76

Dietary Catechols and their Relationship to Microbial Endocrinology  

Microsoft Academic Search

\\u000a This chapter examines the evidence that the ability of neuroendocrine hormones, notably norepinephrine and epinephrine, to\\u000a stimulate bacterial growth in iron-restricted media is not limited to molecules with a catecholamine structure but is also\\u000a possessed by a variety of other catechols, many of which are of plant origin and are common in the diet. Catechols derived\\u000a from the diet, such

Neil Shearer; Nicholas J. Walton

77

Decoration of electrospun nanofibers with monomeric catechols to facilitate cell adhesion.  

PubMed

Monomeric catechols are displayed on the surface of polymeric nanofibers by robust catechol-thiol interactions to enhance cell adhesion and migration. Dihydroxyphenyl propionic acid is chemically conjugated to primary amine groups of poly(?-caprolactone)-poly(ethylene glycol)-amine (PCL-PEG) nanofibers to display catechol moieties on the surface. At basic pH, catecholized nanofibers incorporate thiol groups at a five-fold higher rate than at acidic pH, while catechol-coated surfaces do not show any pH-dependent binding. Live/dead cell staining indicates that the catecholized nanofibers do not exert any cytotoxic effects. Also, NIH 3T3 cells cultured on the catecholized nanofibers show increased attachment and migration that is proportional to the amount of the immobilized catechol moieties on the surface. These results clearly indicate that 6 nmol of monomeric catechols on the surface of nanofiber can promote cell adhesion and migration by thiol-catehol interactions. PMID:24108419

Choi, Ji Suk; Messersmith, Phillip B; Yoo, Hyuk Sang

2014-02-01

78

Optimization of glucose oxidase production by Aspergillus niger using genetic-and process-engineering techniques  

Microsoft Academic Search

Wild-type Aspergillus niger NRRL-3 was transformed with multiple copies of the glucose oxidase structural gene (god). The gene was placed under the control of the gpd A promoter of A. nidulans. For more efficient secretion the a-amylase signal peptide from A oryzae was inserted in front of god. Compared to the wild type, the recombinant strain NRRL-3 (GOD3-18) produced up

K. Hellmuth; S. Pluschkell; J.-K. Jung; E. Ruttkowski; U. Rinas

1995-01-01

79

Catechol-O-methyltransferase and Parkinson's disease.  

PubMed

Parkinson's disease (PD) is one of the main causes of neurological disability in the elderly. Levodopa is the gold standard for treating this disease, but chronic levodopa therapy is complicated by motor fluctuation and dyskinesia. The catechol-O-methyltransferase (COMT) inhibitors represent a new class of antiparkinsonian drugs. When coadministered with levodopa/decarboxylase inhibitor, 2 COMT inhibitors, tolcapone and entacapone have been shown to improve the clinical benefit of levodopa. COMT activity is genetically polymorphic, and individuals with the low activity (COMT(L/L)) genotype have a thermolabile COMT protein; studies suggest that this genotype is less common in Asians than in Caucasians. Differences in COMT activity may determine the individual response to levodopa and result in ethnic differences in PD susceptibility. Our recent study suggests that the COMTL allele can interact with the MAOB gene to increase the occurrence of PD in Taiwanese. In order to understand this new class of antiparkinsonian drugs, we review their basic properties, pharmacology, and clinical efficacy. The frequency distribution of COMT genetic polymorphisms among different populations and its implications in the etiology and drug response is also discussed. PMID:11873938

Tai, Chun-Hwi; Wu, Ruey-Meei

2002-02-01

80

THE SALIVARY CATECHOL OXIDASE\\/PEROXIDASE ACTIVITIES OF THE MOSQUITO ANOPHELES ALBIMANUS  

Microsoft Academic Search

Summary Salivary gland homogenates from adult female Anopheles albimanus mosquitoes relaxed aortic rings preconstricted with noradrenaline (NA). This relaxation is slow and is due to destruction of NA. Incubation of NA with the homogenate yielded a product with a spectrum consistent with the corresponding adrenochrome. Oxidation of NA was enhanced by a superoxide generation system and inhibited by the combined

JOSÉ M. C. RIBEIRO; ROBERTO H. NUSSENZVEIG

1993-01-01

81

Catechol oxidase and phenoxazinone synthase activity of a manganese(II) isoindoline complex  

Microsoft Academic Search

The mononuclear [Mn(6?Me2indH)(H2O)2(CH3CN)](ClO4)2 (6?Me2indH: 1,3-bis(6?-methyl-2?-pyridylimino)isoindoline) complex has been prepared and characterized by various techniques such as elemental analysis, IR, UV–visible and ESR spectroscopy. The title compound was suitable as catalyst for the catalytic oxidation of 3,5-di-tert-butylcatechol (3,5-DTBCH2) to 3,5-di-tert-butyl-1,2-benzoquinone (3,5-DTBQ) (catecholase activity), and o-aminophenol (OAPH) to 2-aminophenoxazine-3-one (APX) (phenoxazinone synthase activity) with dioxygen at ambient condition in good yields. Kinetic

József Kaizer; Gábor Baráth; Róbert Csonka; Gábor Speier; László Korecz; Antal Rockenbauer; László Párkányi

2008-01-01

82

Functional copper requirement for catechol oxidase activity in plantation Eucalyptus species  

Microsoft Academic Search

Copper (Cu) deficiency in eucalypts is associated with tree deformation and reduced wood production from plantations. Presently, diagnosis of the early stages of Cu deficiency is unreliable as critical tissue Cu concentrations for tree growth have not been defined. Since wood quality is usually impaired in advance of tree growth, a biochemical test for Cu deficiency was sought for three

M. J. Gherardi; L. Huang

1999-01-01

83

Structural and functional models for the dinuclear copper active site in catechol oxidases  

Microsoft Academic Search

Two new ?-methoxo-bridged dinuclear copper(II) complexes with a N-substituted sulfonamide, [Cu(?-OMe)(L)(NH3)]2 (1) and [Cu(?-OMe)(L)(DMSO)]2 (2) [HL, N-2-(4-methylbenzothiazole)benzenesulfonamide], have been prepared and characterized by single-crystal X-ray difraction analyses. Compound 1 crystallizes in the monoclinic space group C2\\/c with a=22.0678(18), b=7.9134(7), c=21.1186(18)Ĺ, ?=113.788(4)° and Z=8. Compound 2 crystallizes in the monoclinic space group C2\\/c with a=18.0900(10), b=9.5720(10), c=24.2620(10) Ĺ, ?=98.7120(10)° and Z=8.

Marta González-Álvarez; Gloria Alzuet; Joaqu??n Borrás; Santiago Garc??a-Granda; José Manuel Montejo-Bernardo

2003-01-01

84

Structural and functional studies on model compounds of purple acid phosphatases and catechol oxidases  

Microsoft Academic Search

The synthesis, single crystal X-ray crystallographic, magnetic and electrochemical characterization of eight representative symmetric and unsymmetric complexes as structural model compounds for active sites in PAPs is reported. A mixed valent diiron as well as an iron(III)–zinc(II) complex as models for the active, reduced form of mammalian and plant PAPs, respectively, were synthesized and characterized. Five diiron(III) compounds as structural

Roberto Than; Arnold A. Feldmann; Bernt Krebs

1999-01-01

85

Kinetic studies of dicopper complexes in catechol oxidase model reaction by using an approximationless evaluating method  

Microsoft Academic Search

The oxidation of 3,5-di-tert-butylcatechol to 3,5-di-tert-butyl-o-benzoquinone catalyzed by dinuclear copper(II) complexes {[Cu2(L1)(CF3SO3)2(H2O)4]-(CF3SO3)2 (1) and [Cu2(L2O)](CF3SO3)2 (2)| has been investigated in methanol saturated with O2 at ambient temperature. Detailed kinetic studies were carried out and for the treatment the fitting software ZiTa was applied. On the basis of the results in the kinetic studies a possible mechanism of the catalytic reaction

Katalin Selmeczi; Marius Réglier; Gábor Speier; Gábor Peintler

2004-01-01

86

The genome sequence of Xanthomonas oryzae pathovar oryzae KACC10331, the bacterial blight pathogen of rice  

Microsoft Academic Search

The nucleotide sequence was determined for the genome of Xanthomonas oryzae pathovar oryzae (Xoo) KACC10331, a bacterium that causes bacterial blight in rice (Oryza sativa L.). The genome is com- prised of a single, 4 941 439 bp, circular chromosome that is G 1 C rich (63.7%). The genome includes 4637 open reading frames (ORFs) of which 3340 (72.0%) could

Byoung-Moo Lee; Young-Jin Park; Dong-Suk Park; Hee-Wan Kang; Jeong-Gu Kim; Eun-Sung Song; In-Cheol Park; Ung-Han Yoon; Jang-Ho Hahn; Bon-Sung Koo; Gil-Bok Lee; Hyungtae Kim; Hyun-Seok Park; Kyong-Oh Yoon; Jeong-Hyun Kim; Chol-hee Jung; Nae-Hyung Koh; Jeong-Sun Seo; Seung-Joo Go

2005-01-01

87

Catechol conjugates are in vivo metabolites of Salicis cortex.  

PubMed

After oral administration of 100?mg/kg b.?w. (235.8?ľmol/kg) salicortin to Wistar rats, peak serum concentrations of 1.43?mg/L (13.0?ľM) catechol were detected after 0.5?h in addition to salicylic acid by HPLC-DAD after serum processing with ?-glucuronidase and sulphatase. Both metabolites could also be detected in the serum of healthy volunteers following oral administration of a willow bark extract (Salicis cortex, Salix spec., Salicaceae) corresponding to 240?mg of salicin after processing with both enzymes. In humans, the cmax (1.46?mg/L, 13.3?ľM) of catechol was reached after 1.2?h. The predominant phase-II metabolite in humans and rats was catechol sulphate, determined by HPLC analysis of serum samples processed with only one kind of enzyme. Without serum processing with glucuronidase and sulphatase, no unconjugated catechol could be detected in human and animal serum samples. As catechol is described as an anti-inflammatory compound, these results may contribute to the elucidation of the mechanism of the action of willow bark extract. PMID:24146062

Knuth, Susanne; Abdelsalam, Rania M; Khayyal, Mohamed T; Schweda, Frank; Heilmann, Jörg; Kees, Martin Georg; Mair, Georg; Kees, Frieder; Jürgenliemk, Guido

2013-11-01

88

Purification and characterisation of polyphenol oxidase (PPO) from eggplant (Solanum melongena).  

PubMed

Eggplant (Solanum melongena) is a very rich source of polyphenol oxidase (PPO), which negatively affects its quality upon cutting and postharvest processing due to enzymatic browning. PPO inhibitors, from natural or synthetic sources, are used to tackle this problem. One isoform of PPO was 259-fold purified using standard chromatographic procedures. The PPO was found to be a 112 kDa homodimer. The enzyme showed very low K(m) (0.34 mM) and high catalytic efficiency (3.3×10(6)) with 4-methyl catechol. The substrate specificity was in the order: 4-methyl catechol>tert-butylcatechol>dihydrocaffeic acid>pyrocatechol. Cysteine hydrochloride, potassium metabilsulphite, ascorbic acid, erythorbic acid, resorcylic acid and kojic acid showed competitive inhibition, whereas, citric acid and sodium azide showed mixed inhibition of PPO activity. Cysteine hydrochloride was found to be an excellent inhibitor with the low inhibitor constant of 1.8 ?M. PMID:23442630

Mishra, Bibhuti B; Gautam, Satyendra; Sharma, Arun

2012-10-15

89

Xanthomonas oryzae pv oryzae triggers immediate transcriptomic modulations in rice  

PubMed Central

Background Xanthomonas oryzae pv oryzae is a devastating pathogen of rice and has been extensively studied as a model pathogen of monocotyledons. Expressional studies in both the contenders have been undertaken in past to understand the molecular mechanism underlying the compatible and incompatible interactions in the pathosystem. Continuous update on database and gene annotations necessitates constant updating on the roles of the new entities as well as reinterpretation of regulations of the previous ones. Moreover the past endeavors have addressed the middle or late defense responses of the rice plant whereas in the present study an attempt has been made to investigate the early defense responses taking place immediately after inoculation. Results Microarray was used to study the transcriptional modulations in eighteen days old rice seedling leaves of both susceptible and resistant genotypes one hour after inoculation. In resistant plants as compared to susceptible ones 274 genes were found to be differentially expressed. Annotations could be assigned to 112 up- and 73 down-regulated transcripts and gene interaction maps were generated for 86 transcripts. Expressional data and interaction maps were used to develop a hypothetical scheme of the molecular events taking place during early defense response. Network analysis with the differential transcripts showed up-regulation of major clusters of cell signaling proteins and transcription factors while growth and basal metabolic components were largely found to be down-regulated. Conclusions This study provides an understanding of the early defense signaling in rice cells. Components of the calcium and lipid signaling as well as MAPK cascade were modulated, by signals from surface receptors and cytosolic R-proteins, to arouse jasmonic acid and ethylene signaling and suppress auxin signaling through various transcription factors. Abscisic acid modulation was also evident through the expression regulation of transcription factors involved with its functions. Moreover adjustments in expression levels of components of primary as well as secondary metabolism, protein trafficking and turnout were apparent, highlighting the complexity of defense response. PMID:22289642

2012-01-01

90

Removal of arsenic compounds from spent catecholated polymer  

DOEpatents

Described is a process for removing arsenic from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic bound to it from contacting petroliferous liquid as described above and involves: a. treating said spent catecholated polystyrene, at a temperature in the range of about 20.degree. to 100.degree. C. with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10 and, b. separating the solids and liquids from each other. Preferably the regeneration treatment is in two steps wherein step (a) is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, steps (a) and (b) are repeated using a bicarbonate.

Fish, Richard H. (Berkeley, CA)

1985-01-01

91

Protocatechuate is not metabolized via catechol in Enterobacter aerogenes.  

PubMed Central

Protocatechuate is generally metabolized in bacteria by direct oxygenative cleavage to produce beta-carboxymuconate. An exception to this pattern has been suggested by reports that protocatechuate might be metabolized by nonoxidative decarboxylation to catechol in Enterobacter aerogenes. In the present investigation, analysis of mutant strains indicated that this proposed pathway did not make a significant contribution to protocatechuate metabolism in E. aerogenes because mutations blocking catechol metabolism did not impair protocatechuate utilization. In addition, all the enzymes required for the oxygenative cleavage of protocatechuate and its further metabolism were induced in E. aerogenes during protocatechuate metabolism, and mutations inactivating this oxygenative pathway prevented protocatechuate degradation. The strains of E. aerogenes examined exhibited broad specificities of inductive control over genes associated with protocatechuate and catechol metabolism; it appears that a number of metabolites may trigger the expression of these genes. PMID:3680179

Doten, R C; Ornston, L N

1987-01-01

92

Reactive oxygen species production by catechol stabilized copper nanoparticles  

NASA Astrophysics Data System (ADS)

Stable Cu nanoparticles (NPs) prepared using catechol containing dopamine-based linkers could generate reactive oxygen species (ROS) that can activate peroxidase enzymes and catalyze the degradation of fluorescent dye pollutants.Stable Cu nanoparticles (NPs) prepared using catechol containing dopamine-based linkers could generate reactive oxygen species (ROS) that can activate peroxidase enzymes and catalyze the degradation of fluorescent dye pollutants. Electronic supplementary information (ESI) available: Details of the synthesis of dopamine linkers and Cu NPs, peroxidase activity tests, H2O2 calibration and degradation tests for resorufin, RB and MB. See DOI: 10.1039/c3nr03563h

Chen, Cheng; Ahmed, Ishtiaq; Fruk, Ljiljana

2013-11-01

93

Rice, Japonica (Oryza sativa L.).  

PubMed

The importance of rice, as a food crop, is reflected in the extensive global research being conducted in an effort to improve and better understand this particular agronomic plant. In regard to biotechnology, this has led to the development of numerous genetic transformation protocols. Over the years, many of these methods have become increasingly straightforward, rapid, and efficient, thereby making rice valuable as a model crop for scientific research and functional genomics. The focus of this chapter is on one such protocol that uses Agrobacterium-mediated transformation of Oryza sativa L. ssp. Japonica cv. Nipponbare with an emphasis on tissue desiccation. The explants consist of callus derived from mature seeds which are cocultivated on filter paper postinfection. Hygromycin selection is used for the recovery of subsequent genetically engineered events. PMID:25300839

Main, Marcy; Frame, Bronwyn; Wang, Kan

2015-01-01

94

A homolog of an Escherichia coli phosphate-binding protein gene from Xanthomonas oryzae pv. oryzae  

NASA Technical Reports Server (NTRS)

A Xanthomonas oryzae pv. oryzae gene with sequence similarity to an Escherichia coli phosphate-binding protein gene (phoS) produces a periplasmic protein of apparent M(r) 35,000 when expressed in E. coli. Amino terminal sequencing revealed that a signal peptide is removed during transport to the periplasm in E. coli.

Hopkins, C. M.; White, F. F.; Heaton, L. A.; Guikema, J. A.; Leach, J. E.; Spooner, B. S. (Principal Investigator)

1995-01-01

95

Cholesterol oxidase: biotechnological applications.  

PubMed

Cholesterol oxidase is a bacterial FAD-containing flavooxidase that catalyzes the first reaction in cholesterol catabolism. Indeed, this enzyme catalyzes two reactions: the oxidation of the C(3)-OH group of cholesterol (and other sterols) to give cholest-5-en-3-one; and its isomerization to cholest-4-en-3-one. In the past several years, the structural and functional characterization of cholesterol oxidase has been developed together with its application as a biological tool. Cholesterol oxidase has been used in biocatalysis for the production of a number of steroids, as an insecticidal protein against boll weevil larvae and, in particular, as a diagnostic enzyme for determining serum levels of cholesterol. These applications prompted various laboratories worldwide to isolate this flavooxidase from different sources and to improve its properties by protein engineering, further increasing our knowledge on its structure-function relationships. These studies also discovered new physiological roles for cholesterol oxidase (e.g. in virulence and as an antifungal sensor). We assume that the investigations of cholesterol oxidase and its applications will continue to grow quickly in the near future, in particular to uncover unexpected, new areas of application. PMID:19843167

Pollegioni, Loredano; Piubelli, Luciano; Molla, Gianluca

2009-12-01

96

Purification and characterization of polyphenol oxidase from rape flower.  

PubMed

The purification and partial enzymology characteristics of polyphenol oxidase (PPO) from rape flower were studied. After preliminary treatments, the crude enzyme solution was in turn purified with ammonium sulfate, dialysis, and Sephadex G-75 gel chromatography. The optimal conditions and stability of PPO were examined at different pH values and temperatures. Subsequently, PPO was also characterized by substrate (catechol) concentrations, inhibitors, kinetic parameters, and molecular weight. Results showed that the optimal pH for PPO activity was 5.5 in the presence of catechol and that PPO was relatively stable at pH 3.5-5.5. PPO was moderately stable at temperatures from 60 to 70 °C, whereas it was easily denatured at 80-90 °C. Ethylenediaminetetraacetic acid, sodium chloride, and calcium chloride had little inhibitive effects on PPO, whereas citric acid, sodium sulfite, and ascorbic acid had strongly inhibitive effects. The Michaelis-Menten constant (K(m)) and maximal reaction velocity (V(max)) of PPO were 0.767 mol/L and 0.519 Ab/min/mL of the crude PPO solution, respectively. PPO was finally purified to homogeneity with a purification factor of 4.41-fold and a recovery of 12.41%. Its molecular weight was 60.4 kDa, indicating that the PPO is a dimer. The data obtained in this research may help to prevent the enzymatic browning of rape flower during its storage and processing. PMID:22239496

Sun, Han-Ju; Wang, Jing; Tao, Xue-Ming; Shi, Juan; Huang, Mei-Ying; Chen, Zhe

2012-01-25

97

Transgenic cell lines as a useful tool to study the biochemistry of down-regulation of an endogenous rice gene using a heterologous diamine-oxidase cDNA  

Microsoft Academic Search

Transgenic rice (Oryza sativa L.) cell lines engineered with the pea diamine oxidase cDNA in antisense orientation under the control of two different promoters were recovered using particle bombardment. Plasmids p35Sdaoa and pEdaoa contained the pea diamine oxidase cDNA driven by the CaMV35S and the pea ENOD12 nodulin promoter, respectively. Molecular analyses confirmed the stable integration of the transgene and

Ludovic Bassie; Matthiew Noury; Jean Pierre Wisniewski; Lola Topsom; Paul Christou; Teresa Capell

2000-01-01

98

Diamine oxidase in the hen  

Microsoft Academic Search

In adult hens diamine oxidase (histaminase) activity was found in gastrointestinal tract (with the highest value in ileum), liver and spleen. Intestinal diamine oxidase is predominantly a particle-bound enzyme. In the intestine oxidation of putrescine leads to ?-pyrroline formation, in liver both ?1-pyrroline and ?-aminobutyric acid are formed. The inhibitor properties of hen intestinal and rat intestinal diamine oxidases are

T. Biega?ski; Maria A. Ulatowska

1983-01-01

99

Spinach thylakoid polyphenol oxidase isolation, activation, and properties of the native chloroplast enzyme  

SciTech Connect

Polyphenol oxidase activity (E.C. 1.14,18.1) has been found in two enzyme species isolated from thylakoid membranes of spinach chloroplasts. The proteins were released from the membrane by sonication and purified >900-fold by ammonium sulfate precipitation, gel filtration, and ion-exchange chromatography. The enzymes appear to be the tetramer and monomer of a subunit with a molecular weight of 42,500 as determined by lithium dodecyl sulfate gel electrophoresis. Sonication releases polyphenol oxidase from the membrane largely in the latent state. In the absence of added fatty acids, the isolated enzyme spontaneously, but slowly, activates with time. Purified polyphenol oxidase utilizes o-diphenols as substrates and shows no detectable levels of monophenol or p-diphenol oxidase activities. Suitable substrates include chlorogenic acid, catechol, caffeic acid, pyrogallol, and dopamine; however, the enzyme is substrate-inhibited by the last four at concentrations near their K/sub m/. A large seasonal variation in polyphenol oxidase activity may result from a decrease in enzyme content rather than inhibition of the enzyme present.

Golbeck, J.H.; Cammarata, K.V.

1981-05-01

100

Whole-genome sequencing of Oryza brachyantha reveals mechanisms underlying Oryza genome evolution.  

PubMed

The wild species of the genus Oryza contain a largely untapped reservoir of agronomically important genes for rice improvement. Here we report the 261-Mb de novo assembled genome sequence of Oryza brachyantha. Low activity of long-terminal repeat retrotransposons and massive internal deletions of ancient long-terminal repeat elements lead to the compact genome of Oryza brachyantha. We model 32,038 protein-coding genes in the Oryza brachyantha genome, of which only 70% are located in collinear positions in comparison with the rice genome. Analysing breakpoints of non-collinear genes suggests that double-strand break repair through non-homologous end joining has an important role in gene movement and erosion of collinearity in the Oryza genomes. Transition of euchromatin to heterochromatin in the rice genome is accompanied by segmental and tandem duplications, further expanded by transposable element insertions. The high-quality reference genome sequence of Oryza brachyantha provides an important resource for functional and evolutionary studies in the genus Oryza. PMID:23481403

Chen, Jinfeng; Huang, Quanfei; Gao, Dongying; Wang, Junyi; Lang, Yongshan; Liu, Tieyan; Li, Bo; Bai, Zetao; Luis Goicoechea, Jose; Liang, Chengzhi; Chen, Chengbin; Zhang, Wenli; Sun, Shouhong; Liao, Yi; Zhang, Xuemei; Yang, Lu; Song, Chengli; Wang, Meijiao; Shi, Jinfeng; Liu, Geng; Liu, Junjie; Zhou, Heling; Zhou, Weili; Yu, Qiulin; An, Na; Chen, Yan; Cai, Qingle; Wang, Bo; Liu, Binghang; Min, Jiumeng; Huang, Ying; Wu, Honglong; Li, Zhenyu; Zhang, Yong; Yin, Ye; Song, Wenqin; Jiang, Jiming; Jackson, Scott A; Wing, Rod A; Wang, Jun; Chen, Mingsheng

2013-01-01

101

Isolated sulfite oxidase deficiency.  

PubMed

Isolated sulfite oxidase (SO) deficiency is an autosomal recessively inherited inborn error of sulfur metabolism. In this report of a ninth patient the clinical history, laboratory results, neuropathological findings and a mutation in the sulfite oxidase gene are described. The data from this patient and previously published patients with isolated sulfite oxidase deficiency and molybdenum cofactor deficiency are summarized to characterize this rare disorder. The patient presented neonatally with intractable seizures and did not progress developmentally beyond the neonatal stage. Dislocated lenses were apparent at 2 months. There was increased urine excretion of sulfite and S-sulfocysteine and a decreased concentration of plasma cystine. A lactic acidemia was present for 6 months. Liver sulfite oxidase activity was not detectable but xanthine dehydrogenase activity was normal. The boy died of respiratory failure at 32 months. Neuropathological findings of cortical necrosis and extensive cavitating leukoencephalopathy were reminiscent of those seen in severe perinatal asphyxia suggesting an etiology of energy deficiency. A point mutation that resulted in a truncated protein missing the molybdenum-binding site has been identified. PMID:9050047

Rupar, C A; Gillett, J; Gordon, B A; Ramsay, D A; Johnson, J L; Garrett, R M; Rajagopalan, K V; Jung, J H; Bacheyie, G S; Sellers, A R

1996-12-01

102

Crystallization of carbohydrate oxidase from Microdochium nivale  

PubMed Central

Microdochium nivale carbohydrate oxidase was produced by heterologous recombinant expression in Aspergillus oryzae, purified and crystallized. The enzyme crystallizes with varying crystal morphologies depending on the crystallization conditions. Several different crystal forms were obtained using the hanging-drop vapour-diffusion method, two of which were used for diffraction measurements. Hexagon-shaped crystals (form I) diffracted to 2.66?Ĺ resolution, with unit-cell parameters a = b = 55.7, c = 610.4?Ĺ and apparent space group P6222. Analysis of the data quality showed almost perfect twinning of the crystals. Attempts to solve the structure by molecular replacement did not give satisfactory results. Recently, clusters of rod-shaped crystals (form II) were grown in a solution containing PEG MME 550. These crystals belonged to the monoclinic system C2, with unit-cell parameters a = 132.9, b = 56.6, c = 86.5?Ĺ, ? = 95.7°. Data sets were collected to a resolution of 2.4?Ĺ. The structure was solved by the molecular-replacement method. Model refinement is currently in progress. PMID:19478452

Dušková, Jarmila; Dohnálek, Jan; Skálová, Tereza; Řstergaard, Lars Henrik; Fuglsang, Claus Crone; Kolenko, Petr; Št?pánková, Andrea; Hašek, Jind?ich

2009-01-01

103

Detection of the hydrogen-bond stretching mode in the low-frequency Raman spectrum of catechol and catechol-D2  

NASA Astrophysics Data System (ADS)

Low-frequency Raman spectra of catechol (1,2-dihydroxybenzene) and catechol-d2 have been measured at 130 K. The stretching mode of the intermolecular hydrogen bond, ??, has been assigned at 187 and 184 cm-1, respectively. A short discussion of this assignment and its implications with respect to the previously reported guaiacol (2-methoxyphenol) spectra is presented.

Konschin, Henrik; Tylli, Henrik

104

Detection of the hydrogen-bond stretching mode in the low-frequency Raman spectrum of catechol and catechol-D 2  

NASA Astrophysics Data System (ADS)

Low-frequency Raman spectra of catechol (1,2-dihydroxybenzene) and catechol-d 2 have been measured at 130 K. The stretching mode of the intermolecular hydrogen bond, ??, has been assigned at 187 and 184 cm -1, respectively. A short discussion of this assignment and its implications with respect to the previously reported guaiacol (2-methoxyphenol) spectra is presented.

Konschin, Henrik; Tylli, Henrik

1982-11-01

105

Genomic comparison between Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola, using suppression-subtractive hybridization.  

PubMed

Xanthomonas oryzae pathovar oryzae (Xoo) and X. oryzae pv. oryzicola (Xoc) cause bacterial diseases in rice: leaf blight and leaf streak, respectively. Although both the Asian and the African strains of Xoo induce similar symptoms, they are genetically different, with the African Xoo strains being more closely related to the Asian Xoc. To identify the sequences responsible for differences between African and Asian Xoo strains and their relatedness to Xoc strains, a suppression-subtractive hybridization (SSH) procedure was performed, using the African Xoo MAI1 strain as a tester and the Philippine Xoo PXO86 strain and Xoc BLS256 strain as drivers. A nonredundant set of 134 sequences from MAI1 was generated. Several DNA fragments isolated by SSH were similar to genes of unknown function, hypothetical proteins, genes related to the type III secretion system, and other pathogenicity-related genes. The specificity of various fragments was validated by Southern blot analysis. SSH sequences were compared with several xanthomonad genomes. In silico analysis revealed SSH sequences as specific to strain MAI1, revealing their potential as specific markers for further epidemiological and diagnostic studies. SSH proved to be a useful method for rapidly identifying specific genes among closely related X. oryzae strains. PMID:20487016

Soto-Suárez, Mauricio; González, Carolina; Piégu, Benoît; Tohme, Joe; Verdier, Valérie

2010-07-01

106

OsSERK1 regulates rice development but not immunity to Xanthomonas oryzae pv. oryzae or Magnaporthe oryzae.  

PubMed

Somatic embryogenesis receptor kinase (SERK) proteins play pivotal roles in regulation of plant development and immunity. The rice genome contains two SERK genes, OsSerk1 and OsSerk2. We previously demonstrated that OsSerk2 is required for rice Xa21-mediated resistance to Xanthomonas oryzae pv. oryzae (Xoo) and for normal development. Here we report the molecular characterization of OsSerk1. Overexpression of OsSerk1 results in a semi-dwarf phenotype whereas silencing of OsSerk1 results in a reduced angle of the lamina joint. OsSerk1 is not required for rice resistance to Xoo or Magnaporthe oryzae. Overexpression of OsSerk1 in OsSerk2-silenced lines complements phenotypes associated with brassinosteroid (BR) signaling defects, but not the disease resistance phenotype mediated by Xa21. In yeast, OsSERK1 interacts with itself forming homodimers, and also interacts with the kinase domains of OsSERK2 and BRI1, respectively. OsSERK1 is a functional protein kinase capable of auto-phosphorylation in vitro. We conclude that, whereas OsSERK2 regulates both rice development and immunity, OsSERK1 functions in rice development but not immunity to Xoo and M. oryzae. PMID:25266270

Zuo, Shimin; Zhou, Xiaogang; Chen, Mawsheng; Zhang, Shilu; Schwessinger, Benjamin; Ruan, Deling; Yuan, Can; Wang, Jing; Chen, Xuewei; Ronald, Pamela C

2014-12-01

107

A catechol biosensor based on electrospun carbon nanofibers  

PubMed Central

Summary Carbon nanofibers (CNFs) were prepared by combining electrospinning with a high-temperature carbonization technique. And a polyphenol biosensor was fabricated by blending the obtained CNFs with laccase and Nafion. Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscope (FE-SEM) were, respectively, employed to investigate the structures and morphologies of the CNFs and of the mixtures. Cyclic voltammetry and chronoamperometry were employed to study the electrocatalysis of the catechol biosensor. The results indicated that the sensitivity of the biosensor was 41 ľAˇmM?1, the detection limit was 0.63 ľM, the linear range was 1–1310 ľM and the response time was within 2 seconds, which excelled most other laccase-based biosensor reported. Furthermore, the biosensor showed good repeatability, reproducibility, stability and tolerance to interferences. This novel biosensor also demonstrated its promising application in detecting catechol in real water samples. PMID:24778958

Li, Dawei; Pang, Zengyuan; Chen, Xiaodong; Luo, Lei; Cai, Yibing

2014-01-01

108

Partial purification and characterization of polyphenol oxidase from persimmon.  

PubMed

Activity of polyphenol oxidase (PPO) from "Rojo Brillante" persimmon (Diospyros kaki L.) fruits was characterized. Crude extracts were used for characterization of enzyme activity and stability at different temperatures (60, 70 and 80 °C), pHs (from 3.5 to 7.5) and substrate concentrations (catechol from 0 to 0.5M). Maximum enzyme activity was reached at pH 5.5 and 55 °C. Enzyme stability was higher than PPO activities found in other natural sources, since above pH 5.5 the minimum time needed to achieve an enzyme inactivation of 90% was 70 min at 80 °C. However, at pH 4.0 the enzyme stability decreased, reaching inactivation levels above 90% after 10 min even at 60 °C. Thus it was concluded that acidification can circumvent browning problems caused by PPO activity. Moreover, polyacrylamide gel electrophoresis of the enriched extract revealed the presence of at least four bands with strong oxidase activity, suggesting the existence of different PPO isoforms. PMID:24679782

Navarro, José L; Tárrega, Amparo; Sentandreu, Miguel A; Sentandreu, Enrique

2014-08-15

109

Expression of Aspergillus oryzae phytase gene in Aspergillus oryzae RIB40 niaD(-).  

PubMed

Aspergillus oryzae RIB40 niaD(-) was transformed using a plasmid constructed with the A. oryzae phytase gene and pNAN8142 vector. The culture broth of the transformant, which was grown in a medium containing starch as a carbon source and polyvinylpyrrolidone showed phytase activity of a maximum of 2.0 units ml(-1) at 37 degrees C, pH 5.5. PMID:17270723

Uchida, Hiroyuki; Arakida, Shinya; Sakamoto, Tatsuji; Kawasaki, Haruhiko

2006-12-01

110

Quantitative Measurements of Xanthomonas Oryzae pv. Oryzae Distribution in Rice Using Fluorescent-Labeling  

Microsoft Academic Search

The rice host sensor, XA21, confers robust resistance to most strains of Xanthomonas oryzae pv. oryzae (Xoo), the casual agent of bacterial blight disease. Using in planta fluorescence imaging of Xoo strain PXO99Az expressing a green fluorescent protein (Xoo-gfp) we show that XA21 restricts Xoo spread at the point of infection. This noninvasive and quantitative method to measure spatial distribution

Kazunari Nozue; Chang-Jin Park; Pamela C. Ronald

2011-01-01

111

Catechol-O-methyltransferase as a target for melanoma destruction?  

PubMed

Catechols may interfere in melanogenesis by causing increased levels of toxic quinones. Several catechols and known inhibitors of the enzyme catechol-O-methyltransferase (COMT) were therefore tested for their toxicity towards a pigmented melanoma cell line, UCLA-SO-(M14). The inhibition of thymidine incorporation as a result of exposure to the compounds was measured. All agents were compared to 4-hydroxyanisole (4HA), a depigmenting agent extensively studied as an antimelanoma drug. The compounds were also tested on the epithelial cell line, CNCM-I-(221) in the presence and absence of tyrosinase. All the compounds were more effective than 4HA towards the M14-cells at either 10(-4) M or 10(-5) M. The toxicity of 4HA towards the 221-cells was shown to be completely dependent on the presence of tyrosinase. Effects of the test agents on the 221-cells were also observed in the absence of tyrosinase. Although some of them were shown to be good substrates for tyrosinase only small changes in toxicity were observed as a result of the presence of the enzyme in comparison with 4HA. No direct correlation of the toxicity of the agents and COMT inhibition was observed. The possible mode of action of the compounds through inhibition of COMT and interference in melanogenesis is discussed together with other possibilities and factors involved. PMID:8080447

Smit, N P; Latter, A J; Naish-Byfield, S; Westerhof, W; Pavel, S; Riley, P A

1994-08-17

112

Biological degradation of catechol in wastewater using the sequencing continuous-inflow reactor (SCR)  

PubMed Central

Catechol is used in many industries. It can be removed from wastewater by various methods but biological processes are the most superior and commonly used technology. The SCR is a modified form of SBR used to degrade catechol. The objective of this study was to investigate the performance of SCR for biodegradation and mineralization of catechol under various inlet concentrations (630–1500 mg/L) and hydraulic retention times (HRT) (18–9 h). This study used a bench scale SCR setup to test catechol degradation. The acclimation time of biomass for catechol at degradation at 630 mg/L was 41 d. The SCR operating cycle time was 6 h and the consecutive times taken for aerating, settling and decanting were 4, 1.5 and 0.5 h, respectively. This study investigated the effects of inlet catechol concentration (630–1560 mg/L) and HRT (18–9 h). The average catechol removal efficiencies in steady-state conditions of 630, 930, 12954 and 1559 mg/L of catechol were 98.5%, 98.5%, 98.2% and 96.9% in terms catechol and 97.8%, 97.7%, 96.4% and 94.3% for COD, respectively. SCR with acclimated biomasses could effectively remove the catechol and the corresponding COD from wastewater with concentrations of up to 1560, at the loading rate of 5.38 kg COD/m3.d and at a HRT of up to 13 h. The HRT was determined as an important variable affecting catechol removal from wastewater. Reducing the HRT to below 13 h led to reduced removal of catechol and COD. PMID:24499534

2013-01-01

113

The role of DNA methylation in catechol-enhanced erythroid differentiation of K562 cells  

SciTech Connect

Catechol is one of phenolic metabolites of benzene in vivo. Catechol is also widely used in pharmaceutical and chemical industries. In addition, fruits, vegetables and cigarette smoke also contain catechol. Our precious study showed that several benzene metabolites (phenol, hydroquinone, and 1,2,4-benzenetriol) inhibited erythroid differentiation of K562 cells. In present study, the effect of catechol on erythroid differentiation of K562 cells was investigated. Moreover, to address the role of DNA methylation in catechol-induced effect on erythroid differentiation in K562 cells, methylation levels of erythroid-specific genes were analyzed by Quantitative MassARRAY methylation analysis platform. Benzidine staining showed that exposure to catechol enhanced hemin-induced hemoglobin accumulation in K562 cells in concentration- and time-dependent manners. The mRNA expression of erythroid specific genes, including ?-globin, ?-globin, ?-globin, erythroid 5-aminolevulinate synthase, erythroid porphobilinogen deaminase, and transcription factor GATA-1 genes, showed a significant concentration-dependent increase in catechol-treated K562 cells. The exposure to catechol caused a decrease in DNA methylation levels at a few CpG sites in some erythroid specific genes including ?-globin, ?-globin and erythroid porphobilinogen deaminase genes. These results indicated that catechol improved erythroid differentiation potency of K562 cells at least partly via up-regulating transcription of some erythroid related genes, and suggested that inhibition of DNA methylation might be involved in up-regulated expression of some erythroid related genes. -- Highlights: ? Catechol enhanced hemin-induced hemoglobin accumulation. ? Exposure to catechol resulted in up-regulated expression of erythroid genes. ? Catechol reduced methylation levels at some CpG sites in erythroid genes.

Li, Xiao-Fei; Wu, Xiao-Rong; Xue, Ming; Wang, Yan; Wang, Jie; Li, Yang; Suriguga,; Zhang, Guang-Yao; Yi, Zong-Chun, E-mail: yizc@buaa.edu.cn

2012-11-15

114

Cytokinin Oxidase from Wheat  

PubMed Central

As part of the study of the possible role(s) of CBF-1, a cytokinin-binding protein abundant in wheat embryo, a cytokinin oxidase was found in wheat (Triticum aestivum L.) germ and partially purified by conventional purification techniques and high performance chromatofocusing. This preparation catalyzes conversion of N6-(?2-isopentenyl)adenosine to adenosine at a Vmax of 0.4 nanomol per milligram protein per minute at 30°C and pH 7.5, the Km being 0.3 micromolar. This high affinity and the apparent molecular weight of 40,000 estimated by high performance gel permeation on a Spherogel TSK-3000 SW column indicate that this enzyme is different from other cytokinin oxidases previously reported. Oxygen is required for the reaction, as for other cytokinin oxidases already described. N6-(?2-isopentenyl)adenine and zeatin riboside are also degraded, but N6-(?2-isopentenyl)adenosine-5?-monophosphate is apparently not a substrate. Benzyladenine is degraded, but to a small extent, and it inhibits slightly the degradation of N6-(?2-isopentenyl)adenosine. The degradation of N6-(?2-isopentenyl)adenosine is strongly inhibited by diphenylurea and its highly active derivative N-(2-chloro-4-pyridyl)-N?-phenylurea. PMID:16666895

Laloue, Michel; Fox, J. Eugene

1989-01-01

115

GENOME SEQUENCING AND ANALYSIS OF ASPERGILLUS ORYZAE  

Technology Transfer Automated Retrieval System (TEKTRAN)

The genome of Aspergillus oryzae, an important industrial fungus used in the production of oriental fermented foods, such as soy sauce, miso, and sake, has been sequenced. The genome sequence reveals a wealth of genes encoding secreted enzymes. A comparison with the genome sequences of A. nidulans...

116

Phenol oxidase activity in secondary transformed peat-moorsh soils  

NASA Astrophysics Data System (ADS)

The chemical composition of peat depends on the geobotanical conditions of its formation and on the depth of sampling. The evolution of hydrogenic peat soils is closely related to the genesis of peat and to the changes in water conditions. Due to a number of factors including oscillation of ground water level, different redox potential, changes of aerobic conditions, different plant communities, and root exudes, and products of the degradation of plant remains, peat-moorsh soils may undergo a process of secondary transformation conditions (Sokolowska et al. 2005; Szajdak et al. 2007). Phenol oxidase is one of the few enzymes able to degrade recalcitrant phenolic materials as lignin (Freeman et al. 2004). Phenol oxidase enzymes catalyze polyphenol oxidation in the presence of oxygen (O2) by removing phenolic hydrogen or hydrogenes to from radicals or quinines. These products undergo nucleophilic addition reactions in the presence or absence of free - NH2 group with the eventual production of humic acid-like polymers. The presence of phenol oxidase in soil environments is important in the formation of humic substances a desirable process because the carbon is stored in a stable form (Matocha et al. 2004). The investigations were carried out on the transect of peatland 4.5 km long, located in the Agroecological Landscape Park host D. Chlapowski in Turew (40 km South-West of Pozna?, West Polish Lowland). The sites of investigation were located along Wysko? ditch. The following material was taken from four chosen sites marked as Zbechy, Bridge, Shelterbelt and Hirudo in two layers: cartel (0-50cm) and cattle (50-100cm). The object of this study was to characterize the biochemical properties by the determination of the phenol oxidize activity in two layers of the four different peat-moors soils used as meadow. The phenol oxidase activity was determined spectrophotometrically by measuring quinone formation at ?max=525 nm with catechol as substrate by method of Perucci et al. (2000). In peat the highest activities of phenol oxidase was observed in the combinations marked as Shelterbelt and whereas the lowest - in Zbechy, Bridge and Hirudo. Activities of this enzyme in peat ranged from 15.35 to 38.33 ?mol h-1g d.m soil. Increased activities of phenol oxidase have been recorded on the depth 50-100cm - catotelm (21.74-38.33 ?mol h-1g d.m soil) in comparison with the depth 0-50cm - acrotelm (15.35-28.32 ?mol h-1g d.m soil). References Freeman, C., Ostle N.J., Fener, N., Kang H. 2004. A regulatory role for phenol oxidase during decomposition in peatlands. Soil Biology and Biochemistry, 36, 1663-1667. Matocha Ch.J., Haszler G.R., Grove J.H. 2004. Nitrogen fertilization suppresses soil phenol oxidase enzyme activity in no-tillage systems. Soil Science, 169/10, 708-714. Perucci P., Casucci C., Dumontet S. 2000. An improved method to evaluate the o-diphenol oxidase activity of soil. Soil Biology and Biochemistry, 32, 1927-1933. Sokolowska Z., Szajdak L., Matyka-Sarzy?ska D. 2005. Impact of the degree of secondary transformation on amid-base properties of organic compounds in mucks. Geoderma, 127, 80-90. Szajdak L., Szczepa?ski M., Bogacz A. 2007. Impact of secondary transformation of peat-moorsh soils on the decrease of nitrogen and carbon compounds in ground water. Agronomy Research, 5/2, 189-200.

Sty?a, K.; Szajdak, L.

2009-04-01

117

Polyamine Oxidase and Diamine Oxidase Activities in Acute Ureteral Obstruction  

Microsoft Academic Search

The polyamines (spermine, spermidine and putrescine) are present in all mammalian cells. These are essential for the normal growth and differentiation of animal tissues [1]. Their levels may dramatically increase in body fluids as a consequence of tissue damage and regeneration [2]. The major catabolic pathway for polyamines is oxidative deamination by polyamine oxidase (PAO) [3]. Diamine oxidase (EC 1.4.3.6)

1998-01-01

118

Reactive oxygen species production and activation mechanism of the rice NADPH oxidase OsRbohB.  

PubMed

Reactive oxygen species (ROS) produced by plant NADPH oxidases (NOXes) are important in plant innate immunity. The Oryza sativa respiratory burst oxidase homologue B (OsRbohB) gene encodes a NOX the regulatory mechanisms of which are largely unknown. Here, we used a heterologous expression system to demonstrate that OsRbohB shows ROS-producing activity. Treatment with ionomycin, a Ca(2+) ionophore, and calyculin A, a protein phosphatase inhibitor, activated ROS-producing activity; it was thus OsRbohB activated by both Ca(2+) and protein phosphorylation. Mutation analyses revealed that not only the first EF-hand motif but also the upstream amino-terminal region were necessary for Ca(2+)-dependent activation, while these regions are not required for phosphorylation-induced ROS production. PMID:22528669

Takahashi, Shinya; Kimura, Sachie; Kaya, Hidetaka; Iizuka, Ayako; Wong, Hann Ling; Shimamoto, Ko; Kuchitsu, Kazuyuki

2012-07-01

119

Sensitive Detection of Xanthomonas oryzae Pathovars oryzae and oryzicola by Loop-Mediated Isothermal Amplification  

PubMed Central

Molecular diagnostics for crop diseases can enhance food security by enabling the rapid identification of threatening pathogens and providing critical information for the deployment of disease management strategies. Loop-mediated isothermal amplification (LAMP) is a PCR-based tool that allows the rapid, highly specific amplification of target DNA sequences at a single temperature and is thus ideal for field-level diagnosis of plant diseases. We developed primers highly specific for two globally important rice pathogens, Xanthomonas oryzae pv. oryzae, the causal agent of bacterial blight (BB) disease, and X. oryzae pv. oryzicola, the causal agent of bacterial leaf streak disease (BLS), for use in reliable, sensitive LAMP assays. In addition to pathovar distinction, two assays that differentiate X. oryzae pv. oryzae by African or Asian lineage were developed. Using these LAMP primer sets, the presence of each pathogen was detected from DNA and bacterial cells, as well as leaf and seed samples. Thresholds of detection for all assays were consistently 104 to 105 CFU ml?1, while genomic DNA thresholds were between 1 pg and 10 fg. Use of the unique sequences combined with the LAMP assay provides a sensitive, accurate, rapid, simple, and inexpensive protocol to detect both BB and BLS pathogens. PMID:24837384

Lang, Jillian M.; Langlois, Paul; Nguyen, Marian Hanna R.; Triplett, Lindsay R.; Purdie, Laura; Holton, Timothy A.; Djikeng, Appolinaire; Vera Cruz, Casiana M.; Verdier, Valérie

2014-01-01

120

Direct spectrophotometric assay of monooxygenase and oxidase activities of mushroom tyrosinase in the presence of synthetic and natural substrates  

Microsoft Academic Search

Alternative substrates were synthesized to allow direct and continuous spectrophotometric assay of both monooxygenase (cresolase) and oxidase (catecholase) activities of mushroom tyrosinase (MT). Using diazo derivatives of phenol, 4-[(4-methoxybenzo)azo]-phenol, 4-[(4-methylphenyl)azo]-phenol, 4-(phenylazo)-phenol, and 4-[(4-hydroxyphenyl)azo]-benzenesulfonamide, and diazo derivatives of catechol 4-[(4-methylbenzo)azo]-1,2-benzenediol, 4-(phenylazo)-1,2-benzenediol, and 4-[(4-sulfonamido)azo]-1,2 benzenediol (SACat), as substrates allows measurement of the rates of the corresponding enzymatic reactions through recording of the

Kamahldin Haghbeen; Eng Wue Tan

2003-01-01

121

Electronic Structure and Spectra of Catechol and Alizarin in the Gas Phase and Attached to Titanium  

E-print Network

Electronic Structure and Spectra of Catechol and Alizarin in the Gas Phase and Attached to Titanium and alizarin molecules upon binding to titanium. Catechol and alizarin are similar chromophores with analogous electronic spectra in the free state. Binding alizarin to titanium red-shifts the spectrum. The binding

122

Detection of Catechol by Potentiometric-Flow Injection Analysis in the Presence of Interferents  

ERIC Educational Resources Information Center

This article describes an undergraduate analytical chemistry experiment developed to teach instrumental lab skills while incorporating common interferents encountered in the real-world analysis of catechol. The lab technique incorporates potentiometric-flow injection analysis on a dibenzo-18-crown-6 dual platinum electrode to detect catechol in…

Lunsford, Suzanne K.; Widera, Justyna; Zhang, Hong

2007-01-01

123

Removal of airborne toxic chemicals by porous organic polymers containing metal-catecholates.  

PubMed

Porous organic polymers bearing metal-catecholate groups were evaluated for their ability to remove airborne ammonia, cyanogen chloride, sulphur dioxide, and octane by micro-breakthrough analysis. For ammonia, the metal-catecholate materials showed remarkable uptake under humid conditions. PMID:23463320

Weston, Mitchell H; Peterson, Gregory W; Browe, Matthew A; Jones, Paulette; Farha, Omar K; Hupp, Joseph T; Nguyen, Sonbinh T

2013-04-14

124

Inhibition of human catechol- O-methyltransferase (COMT)-mediated O-methylation of catechol estrogens by major polyphenolic components present in coffee  

Microsoft Academic Search

In the present study, we investigated the inhibitory effect of three catechol-containing coffee polyphenols, chlorogenic acid, caffeic acid and caffeic acid phenethyl ester (CAPE), on the O-methylation of 2- and 4-hydroxyestradiol (2-OH-E2 and 4-OH-E2, respectively) catalyzed by the cytosolic catechol-O-methyltransferase (COMT) isolated from human liver and placenta. When human liver COMT was used as the enzyme, chlorogenic acid and caffeic

Bao Ting Zhu; Pan Wang; Mime Nagai; Yujing Wen; Hyoung-Woo Bai

2009-01-01

125

Gene prioritization of resistant rice gene against Xanthomas oryzae pv. oryzae by using text mining technologies.  

PubMed

To effectively assess the possibility of the unknown rice protein resistant to Xanthomonas oryzae pv. oryzae, a hybrid strategy is proposed to enhance gene prioritization by combining text mining technologies with a sequence-based approach. The text mining technique of term frequency inverse document frequency is used to measure the importance of distinguished terms which reflect biomedical activity in rice before candidate genes are screened and vital terms are produced. Afterwards, a built-in classifier under the chaos games representation algorithm is used to sieve the best possible candidate gene. Our experiment results show that the combination of these two methods achieves enhanced gene prioritization. PMID:24371834

Xia, Jingbo; Zhang, Xing; Yuan, Daojun; Chen, Lingling; Webster, Jonathan; Fang, Alex Chengyu

2013-01-01

126

Catechol-O-methyltransferase decreases levodopa toxicity in vitro.  

PubMed

The purpose of this study was to examine the effects of 3-O-methylation by catechol-O-methyltransferase (COMT) on the toxicity of levodopa in neuronal cultures. High concentrations of levodopa are toxic in vitro. Therefore, there is concern that long-term treatment with levodopa in patients with Parkinson's disease might accelerate the rate of degeneration of nigrostriatal neurons. However, recent studies have suggested that, while levodopa is harmful in vitro, it may not be toxic in vivo. A possible defense mechanism is by means of metabolic shunting of levodopa excess to 3-O-methyldopa by COMT in peripheral and central nervous system tissues. In this study we examine whether the use of COMT inhibitor, which reduced the levels of 3-O-methyldopa, affect levodopa toxicity. Mice cerebellar granule neurons, PC12, and neuroblastoma cells were used, and their viability following exposure to levodopa and COMT with and without tolcapone, a COMT inhibitor, was measured by neutral red staining. Auto-oxidation of levodopa was evaluated using a spectrophotometer (690 nm). We found that 3-O-methyldopa, unlike levodopa, was not toxic to all cells examined. Addition of purified COMT to levodopa prevented its auto-oxidation and markedly attenuated its cytotoxicity in vitro. Additional tolcapone reversed the protective effect of COMT. The agent 3-O-methyldopa is not toxic to cell cultures. Catechol-O-methyltransferase attenuates toxicity of levodopa in vitro by its metabolism to nontoxic 3-O-methyldopa. PMID:11290879

Offen, D; Panet, H; Galili-Mosberg, R; Melamed, E

2001-01-01

127

Mapping the conformational space accessible to catechol-O-methyltransferase  

PubMed Central

Methylation catalysed by catechol-O-methyltransferase (COMT) is the main pathway of catechol neurotransmitter deactivation in the prefrontal cortex. Low levels of this class of neurotransmitters are held to be causative of diseases such as schizophrenia, depression and Parkinson’s disease. Inhibition of COMT may increase neurotransmitter levels, thus offering a route for treatment. Structure-based drug design hitherto seems to be based on the closed enzyme conformation. Here, a set of apo, semi-holo, holo and Michaelis form crystal structures are described that define the conformational space available to COMT and that include likely intermediates along the catalytic pathway. Domain swaps and sizeable loop movements around the active site testify to the flexibility of this enzyme, rendering COMT a difficult drug target. The low affinity of the co-substrate S-adenosylmethionine and the large conformational changes involved during catalysis highlight significant energetic investment to achieve the closed conformation. Since each conformation of COMT is a bona fide target for inhibitors, other states than the closed conformation may be promising to address. Crystallographic data for an alternative avenue of COMT inhibition, i.e. locking of the apo state by an inhibitor, are presented. The set of COMT structures may prove to be useful for the development of novel classes of inhibitors. PMID:25084335

Ehler, Andreas; Benz, Jörg; Schlatter, Daniel; Rudolph, Markus G.

2014-01-01

128

MAPPING R-GENES IN RICE WILD RELATIVES (ORYZA SPP.)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rice sheath blight caused by Rhizoctonia solani Kühn and leaf blast caused by Magnaporthe grisea (T.T. Herbert) Yaegashi & Udagawa are major fungal diseases of cultivated rice (Oryza sativa L.). Rice wild relatives (Oryza spp.) are the source of several resistance (R-) genes including those for bla...

129

Telomere-mediated chromosomal truncation in Aspergillus oryzae.  

PubMed

We truncated the short arm of chromosome 3 to delete the aflatoxin biosynthesis gene homolog cluster using telomeric repeats in Aspergillus oryzae. The predicted deletion was confirmed by Southern blot analyses. This telomere-mediated chromosomal truncation method enables the development of an artificial chromosome in A. oryzae. PMID:25034635

Tada, Sawaki; Ohkuchi, Hikaru; Matsushita-Morita, Mayumi; Furukawa, Ikuyo; Hattori, Ryota; Suzuki, Satoshi; Kashiwagi, Yutaka; Kusumoto, Ken-Ichi

2015-01-01

130

Lactic acid production from xylose by the fungus Rhizopus oryzae  

Microsoft Academic Search

Lignocellulosic biomass is considered nowadays to be an economically attractive carbohydrate feedstock for large-scale fermentation of bulk chemicals such as lactic acid. The filamentous fungus Rhizopus oryzae is able to grow in mineral medium with glucose as sole carbon source and to produce optically pure l(+)-lactic acid. Less is known about the conversion by R. oryzae of pentose sugars such

Ronald H. W. Maas; Robert R. Bakker; Gerrit Eggink; Ruud A. Weusthuis

2006-01-01

131

Cytochrome oxidase: an alternative model.  

PubMed Central

Oxidative titration of reduced cytochrome oxidase (cytochrome c oxidase; ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1) in the presence of carbon monoxide and sulfide, at potentials greater than +500 mV (vs. the neutral hydrogen electrode), have failed to produce new copper signals in the electron paramagnetic resonance spectrum of this enzyme. This observation implies that once of the copper centers in cytochrome oxidase remains Cu(I) under strongly oxidizing conditions. The rationalization of this fact, and the possible explanation of a great accumulation of spectroscopic data, is that cytochrome a3 may be a two-electron redox center, with stable Fe(IV), Fe(III), and Fe(II) states during its redox cycle. This oxidase model does not require an antiferromagnetic coupling scheme, in contrast to currently prevalent models. PMID:6246505

Seiter, C H; Angelos, S G

1980-01-01

132

Plasma postheparin diamine oxidase activity  

Microsoft Academic Search

Plasma diamine oxidase (DAO) activity may reflect intestinal involvement in Crohn's disease. The purpose of this study was\\u000a to develop a simple heparin stimulation test for assessing postheparin plasma diamine oxidase activity in Crohn's disease.\\u000a Ten volunteers and five patients with Crohn's disease received 1000 units and 3000 units of heparin intravenously and plasma\\u000a samples were obtained at timed intervals.

Jon S. Thompson; David A. Burnett; Robert A. Cormier; William P. Vaughan

1988-01-01

133

Assessment of genetic diversity and population structure of Xanthomonas oryzae pv. oryzae with a repetitive DNA element.  

PubMed Central

A repetitive DNA element cloned from Xanthomonas oryzae pv. oryzae was used to assess the population structure and genetic diversity of 98 strains of X. oryzae pv. oryzae collected between 1972 and 1988 from the Philippine Islands. Genomic DNA from X. oryzae pv. oryzae was digested with EcoRI and analyzed for restriction fragment length polymorphisms (RFLPs) with repetitive DNA element as a probe. Twenty-seven RFLP types were identified; there was no overlap of RFLP types among the six races from the Philippines. Most variability (20 RFLP types) was found in strains of races 1, 2, and 3, which were isolated from tropical lowland areas. Four RFLP types (all race 5) were found among strains isolated from cultivars grown in the temperate highlands. The genetic diversity of the total population of X. oryzae pv. oryzae was 0.93, of which 42% was due to genetic differentiation between races. The genetic diversities of strains collected in 1972 to 1976, 1977 to 1981, and 1982 to 1986, were 0.89, 0.90, and 0.92, respectively, suggesting a consistently high level of variability in the pathogen population over the past 15 years. Cluster analysis based on RFLP banding patterns showed five groupings at 85% similarity. The majority of strains from a given race were contained within one cluster, except for race 3 strains, which were distributed in three of the five clusters. Images PMID:1353345

Leach, J E; Rhoads, M L; Vera Cruz, C M; White, F F; Mew, T W; Leung, H

1992-01-01

134

Role of the FeoB Protein and Siderophore in Promoting Virulence of Xanthomonas oryzae pv. oryzae on Rice?  

PubMed Central

Xanthomonas oryzae pv. oryzae causes bacterial blight, a serious disease of rice. Our analysis revealed that the X. oryzae pv. oryzae genome encodes genes responsible for iron uptake through FeoB (homolog of the major bacterial ferrous iron transporter) and a siderophore. A mutation in the X. oryzae pv. oryzae feoB gene causes severe virulence deficiency, growth deficiency in iron-limiting medium, and constitutive production of a siderophore. We identified an iron regulated xss gene cluster, in which xssABCDE (Xanthomonas siderophore synthesis) and xsuA (Xanthomonas siderophore utilization) genes encode proteins involved in biosynthesis and utilization of X. oryzae pv. oryzae siderophore. Mutations in the xssA, xssB, and xssE genes cause siderophore deficiency and growth restriction under iron-limiting conditions but are virulence proficient. An xsuA mutant displayed impairment in utilization of native siderophore, suggesting that XsuA acts as a specific receptor for a ferric-siderophore complex. Histochemical and fluorimetric assays with gusA fusions indicate that, during in planta growth, the feoB gene is expressed and that the xss operon is not expressed. This study represents the first report describing a role for feoB in virulence of any plant-pathogenic bacterium and the first functional characterization of a siderophore-biosynthetic gene cluster in any xanthomonad. PMID:20382771

Pandey, Alok; Sonti, Ramesh V.

2010-01-01

135

Identification of catechols as histone-lysine demethylase inhibitors.  

PubMed

Identification of inhibitors of histone-lysine demethylase (HDM) enzymes is important because of their involvement in the development of cancer. An ELISA-based assay was developed for identification of inhibitors of the HDM KDM4C in a natural products library. Based on one of the hits with affinity in the low ?M range (1, a catechol), a subset of structurally related compounds was selected and tested against a panel of HDMs. In this subset, two inhibitors (2 and 10) had comparable affinities towards KDM4C and KDM6A but no effect on PHF8. One inhibitor restored H3K9me3 levels in KDM4C transfected U2-OS cells. PMID:22575654

Nielsen, Anders L; Kristensen, Line H; Stephansen, Karen B; Kristensen, Jan B L; Helgstrand, Charlotte; Lees, Michael; Cloos, Paul; Helin, Kristian; Gajhede, Michael; Olsen, Lars

2012-04-24

136

Quinone Reductase 2 Is a Catechol Quinone Reductase  

SciTech Connect

The functions of quinone reductase 2 have eluded researchers for decades even though a genetic polymorphism is associated with various neurological disorders. Employing enzymatic studies using adrenochrome as a substrate, we show that quinone reductase 2 is specific for the reduction of adrenochrome, whereas quinone reductase 1 shows no activity. We also solved the crystal structure of quinone reductase 2 in complexes with dopamine and adrenochrome, two compounds that are structurally related to catecholamine quinones. Detailed structural analyses delineate the mechanism of quinone reductase 2 specificity toward catechol quinones in comparison with quinone reductase 1; a side-chain rotational difference between quinone reductase 1 and quinone reductase 2 of a single residue, phenylalanine 106, determines the specificity of enzymatic activities. These results infer functional differences between two homologous enzymes and indicate that quinone reductase 2 could play important roles in the regulation of catecholamine oxidation processes that may be involved in the etiology of Parkinson disease.

Fu, Yue; Buryanovskyy, Leonid; Zhang, Zhongtao (NYMEDCO)

2008-09-05

137

Characterization of polyphenol oxidase activity in Ataulfo mango.  

PubMed

Crude extracts of Ataulfo exhibited polyphenol oxidase (PPO) activity with pyrogallol, 3-methylcatechol, catechol, gallic acid, and protocatechuic acid. The substrate dependent pH optima ranged from pH 5.4 to 6.4 with Michaelis-Menten constants between 0.84 ą 0.09 and 4.6 ą 0.7 mM measured in MES or phosphate buffers. The use of acetate buffers resulted in larger Michaelis-Menten constants, up to 14.62 ą 2.03 mM. Sodium ascorbate, glutathione, and kojic acid are promising inhibitors to prevent enzymatic browning in Ataulfo. PPO activity increased with ripeness and was always higher in the skin compared to the pulp. Sodium dodecyl sulphate (SDS) enhanced PPO activity, with pulp showing a stronger increase than skin. SDS-PAGE gels stained for catecholase activity showed multiple bands, with the most prominent bands at apparent molecular weights of 53, 112, and 144 kDa. PMID:25308684

Cheema, Summervir; Sommerhalter, Monika

2015-03-15

138

NADPH Oxidases in Vascular Pathology  

PubMed Central

Abstract Significance: Reactive oxygen species (ROS) play a critical role in vascular disease. While there are many possible sources of ROS, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases play a central role. They are a source of “kindling radicals,” which affect other enzymes, such as nitric oxide synthase endothelial nitric oxide synthase or xanthine oxidase. This is important, as risk factors for atherosclerosis (hypertension, diabetes, hypercholesterolemia, and smoking) regulate the expression and activity of NADPH oxidases in the vessel wall. Recent Advances: There are seven isoforms in mammals: Nox1, Nox2, Nox3, Nox4, Nox5, Duox1 and Duox2. Nox1, Nox2, Nox4, and Nox5 are expressed in endothelium, vascular smooth muscle cells, fibroblasts, or perivascular adipocytes. Other homologues have not been found or are expressed at very low levels; their roles have not been established. Nox1/Nox2 promote the development of endothelial dysfunction, hypertension, and inflammation. Nox4 may have a role in protecting the vasculature during stress; however, when its activity is increased, it may be detrimental. Calcium-dependent Nox5 has been implicated in oxidative damage in human atherosclerosis. Critical Issues: NADPH oxidase-derived ROS play a role in vascular pathology as well as in the maintenance of normal physiological vascular function. We also discuss recently elucidated mechanisms such as the role of NADPH oxidases in vascular protection, vascular inflammation, pulmonary hypertension, tumor angiogenesis, and central nervous system regulation of vascular function and hypertension. Future Directions: Understanding the role of individual oxidases and interactions between homologues in vascular disease is critical for efficient pharmacological regulation of vascular NADPH oxidases in both the laboratory and clinical practice. Antioxid. Redox Signal. 20, 2794–2814. PMID:24180474

Konior, Anna; Schramm, Agata; Czesnikiewicz-Guzik, Marta

2014-01-01

139

?-cyclodextrin-cobalt ferrite nanocomposite as enhanced sensing platform for catechol determination.  

PubMed

An electrochemical sensor based on ?-cyclodextrin-cobalt ferrite nanocomposite was developed for the sensitive detection of catechol (CT). To construct the base of the sensor, a novel composite was initially fabricated and used as the substrate material by combining cobalt ferrite nanocomposite and ?-cyclodextrin via a simple sonication-induced assembly. Due to the high catechol-loading capacity on the electrode surface and the upstanding electric conductivity of cobalt ferrite nanocomposite, the electrochemical response of the fabricated sensor was greatly enhanced and displayed excellent analytical performance for catechol detection from 1 to 200 ?M with a low detection limit of 0.12 ?M (S/N=3). Moreover, the developed electrochemical sensor exhibited good selectivity and acceptable reproducibility and could be used for the detection of catechol in water samples. PMID:22659205

Han, Jin-Tu; Huang, Ke-Jing; Li, Jing; Liu, Yan-Ming; Yu, Meng

2012-10-01

140

Direct biocatalytic synthesis of functionalized catechols: a green alternative to traditional methods with high effective  

E-print Network

dehydrogenase (DHCD), the first two enzymes in the natural biodegradation pathway of aromatics by Pseudomonas in this area. This paper describes the use of whole-cell organisms to oxygenate aromatics directly to catechols

Hudlicky, Tomas

141

Immobilization of tyrosinase and alcohol oxidase in conducting copolymers of thiophene functionalized poly(vinyl alcohol) with pyrrole.  

PubMed

Immobilization of tyrosinase and alcohol oxidase is achieved in the copolymer of pyrrole with vinyl alcohol with thiophene side groups (PVATh-co-PPy) which is a newly synthesized conducting polymer. PVATh-co-PPy/alcohol oxidase and PVATh-co-PPy/tyrosinase electrodes are constructed by the entrapment of enzyme in conducting copolymer matrix during electrochemical copolymerization. For tyrosinase and alcohol oxidase enzymes, catechol and ethanol are used as the substrates, respectively. Kinetic parameters: maximum reaction rates (V(max)) and Michaelis-Menten constants (K(m)) are obtained. V(max) and K(m) are found as 2.75 micromol/(minelectrode) and 18 mM, respectively, for PVATh-co-PPy/alcohol oxidase electrode and as 0.0091micromol/(minelectrode) and 40 mM, respectively, for PVATh-co-PPy/tyrosinase electrode. Maximum temperature and pH values are investigated and found that both electrodes have a wide working range with respect to both temperature and pH. Operational and storage stabilities show that although they have limited storage stabilities, the enzyme electrodes are useful with respect to operational stabilities. PMID:17555810

Yildiz, Huseyin Bekir; Sahmetlioglu, Ertugrul; Boyukbayram, Ayse Elif; Toppare, Levent; Yagci, Yusuf

2007-08-01

142

A new phenol oxidase produced during melanogenesis and encystment stage in the nitrogen-fixing soil bacterium Azotobacter chroococcum.  

PubMed

Laccases are copper-containing phenol oxidases that are commonly found in many types of plant, insect, fungi and bacteria. Whilst phenol oxidases have been well characterized in fungal species, laccase-type enzymes originating from bacteria have been much less well defined. Bacteria belonging to the family Azotobacteraceae share many morphological characteristics with strains already known to exhibit polyphenol and phenol oxidase activity; and hence the aim of this work was to identify and characterize a novel laccase from the isolated strain Azotobacter chroococcum SBUG 1484 in an attempt to provide further understanding of the roles such enzymes play in physiological development. Laccase activity was clearly observed through oxidation of 2,6-dimethoxyphenol, other typical substrates including: methoxy-monophenols, ortho- and para-diphenols, 4-hydroxyindole, and the non-phenolic compound para-phenylenediamine. A. chroococcum SBUG 1484 showed production of a cell-associated phenol oxidase when grown under nitrogen-fixing conditions, and was also observed when cells enter the melanogenic and encystment stages of growth. Catechol which is structurally related to melanin compounds was also released from Azotobacter cells into the surrounding culture medium during nitrogen-fixing growth. From our results we propose that a membrane-bound laccase plays an important role in the formation of melanin, which was monitored to correlate with progression of A. chroococcum SBUG 1484 cells into the encystment stage of growth. PMID:21327414

Herter, Susanne; Schmidt, Marlen; Thompson, Mark L; Mikolasch, Annett; Schauer, Frieder

2011-05-01

143

A new dinuclear unsymmetric copper(II) complex as model for the active site of catechol oxidase  

Microsoft Academic Search

The crystal structure, magnetic, redox and spectroscopic properties of a novel unsymmetrical dinuclear copper(II) complex, prepared by the reaction between copper(II) perchlorate, sodium acetate and the unsymmetrical, binucleating ligand HTPPNOL, where HTPPNOL is N,N,N?-tris-(2-pyridylmethyl)-1,3-diaminopropan-2-ol, is reported. HTPPNOL (1 equiv.) reacted with 1 equiv. of copper(II) ion, in methanol, and produced the mononuclear copper complex [Cu(TPPNOL)](ClO4)(BPh4) (1). On the other hand,

Christiane Fernandes; Ademir Neves; Adailton J Bortoluzzi; Antônio S Mangrich; Eva Rentschler; Bruno Szpoganicz; Erineu Schwingel

2001-01-01

144

Characterization and catechole oxidase activity of a family of copper complexes coordinated by tripodal pyrazole-based ligands  

Microsoft Academic Search

A family of tripodal pyrazole-based ligands has been synthesized by a condensation reaction between 1-hydroxypyrazoles and aminoalcohols. The diversity was introduced both on the substituents of the pyrazole ring and on the side chain. The corresponding copper(II) complexes have been prepared by reaction with CuCl2 in tetrahydrofuran. They have been characterized by EPR, UV spectroscopy and cyclic voltammetry. The absence

R. Marion; M. Zaarour; N. A. Qachachi; N. M. Saleh; F. Justaud; D. Floner; O. Lavastre; F. Geneste

2011-01-01

145

Investigating the effects of metals on phenol oxidase-producing nitrogen-fixing Azotobacter chroococcum.  

PubMed

Expression of phenol oxidases (PO) in bacteria is often observed during physiological and morphological changes; in the nitrogen-fixing strain Azotobacter chroococcum SBUG 1484, it is accompanied by the formation of encysted cells and melanin. Herein, we studied the effects of copper and the depletion of the nitrogenase-relevant metals molybdenum and iron on physiological characteristics such as culture pigmentation, release of ortho-dihydroxylated melanin precursors, and expression of PO activity in A. chroococcum. Biomass production and melanogenic appearance were directly affected by the depletion of either iron or molybdenum, or in the absence of both metals. Only nitrogen-fixing cells growing in the presence of both metals and cultures supplemented with iron (molybdenum starved) showed the ability to produce an intensively brown-black melanin pigment typically associated with A. chroococcum. Accordingly, PO production was only detected in the presence of both metals and in iron-supplemented cultures starved of molybdenum. The total amount of catecholate siderophores produced by nitrogen-fixing melanogenic cells was considerably higher than in cultures starved of metal ions. Induction of enhanced PO activity was stimulated by additional copper sulfate, possibly related to cellular processes involved in the detoxification of this particular metal, and revealed distinct release of the ortho-dihydroxylated melanin precursors catechol and 3,4-dihydroxybenzoic acid. PMID:22961388

Herter, Susanne; Schmidt, Marlen; Thompson, Mark L; Mikolasch, Annett; Schauer, Frieder

2013-06-01

146

Effect of Sesbania rostrata on Hirschmanniella oryzae in Flooded Rice  

PubMed Central

Microplot experiments on flooded soil infested with Hirschmanniella oryzae were conducted to investigate the influence of the legum Sesbania rostrata as a rotation crop with rice, Oryza sativa L. cv. Moroberekan. To avoid a green manure effect from S. rostrata, all aerial parts were removed at harvest. The dry weight of paddy, culms and leaves, and number of culms of rice following Sesbania were 214%, 158%, and 121% greater, respectively, than those following rice. Ripening of the paddy occurred earlier if rice followed Sesbania. The beneficial effect of Sesbania may have been due to the trap-crop action of Sesbania against H. oryzae. PMID:19295801

Germani, G.; Reversat, G.; Luc, M.

1983-01-01

147

Expression of alternative oxidase in tomato  

SciTech Connect

Tomato fruit ripening is characterized by an increase in ethylene biosynthesis, a burst in respiration (i.e. the climacteric), fruit softening and pigmentation. As whole tomatoes ripened from mature green to red, there was an increase in the alternative oxidase capacity. Aging pink tomato slices for 24 and 48 hrs also showed an increase of alternative oxidase and cytochrome oxidase capacities. Monoclonal antibodies prepared to the Sauromatum guttatum alternative oxidase were used to follow the appearance of alternative oxidase in tomato fruits. There is a corresponding increase in a 36kDa protein with an increase in alternative oxidase capacity. Effects of ethylene and norbornadiene on alternative oxidase capacity were also studied. We are using an alternative oxidase cDNA clone from potato to study the expression of mRNA in ripening and wounded tomatoes to determine if the gene is transcriptionally regulated.

Kakefuda, M.; McIntosh, L. (Michigan State Univ., East Lansing (USA))

1990-05-01

148

Cytochrome P-450 3A and 2D6 catalyze ortho hydroxylation of 4-hydroxytamoxifen and 3-hydroxytamoxifen (droloxifene) yielding tamoxifen catechol: involvement of catechols in covalent binding to hepatic proteins.  

PubMed

Earlier study suggested that 3,4-dihydroxytamoxifen (tam catechol), a tamoxifen metabolite, is proximate to the reactive intermediate that binds covalently to proteins and possibly to DNA (). The current study demonstrates that rat and human hepatic cytochrome P-450s (CYPs) catalyze tam catechol formation from tamoxifen (tam), 3-hydroxy-tam (Droloxifene), and 4-hydroxy-tam (4-OH-tam). Higher levels of catechol were formed from 4-OH-tam and 3-hydroxy-tam than from tam. Evidence that human hepatic CYP3A4 and 2D6 catalyze the formation of tam catechol from 4-OH-tam and supportive data that the catechol is proximate to the reactive intermediate, was obtained: 1) There was a good correlation (r = 0.82; p catechol formation from 4-OH-tam and its covalent binding to proteins in human liver microsomes; 3) low levels of ketoconazole inhibited catechol tam accumulation and covalent binding of 4-OH-tam to human liver proteins; 4) among human P-450s expressed in insect cells (supersomes), only CYP3A4 and 2D6 noticeably catalyzed catechol formation, and cytochrome b5 markedly stimulated the CYP3A4 catalysis; and 5) human livers with high CYP3A and low or high CYP2D6 activity exhibited high catechol formation and those with low 3A and 2D6 activities formed only little catechol. These findings demonstrate that CYP3A4 and to a lesser extent 2D6 catalyze tam catechol formation and support the participation of tam catechol in covalent binding to proteins. PMID:10348797

Dehal, S S; Kupfer, D

1999-06-01

149

A mediated polyphenol oxidase biosensor immobilized by electropolymerization of 1,2-diamino benzene.  

PubMed

A biosensor based on a partially purified polyphenol oxidase (PPO) enzyme was developed by using electropolymerization of [(2,2'-bipyridine)(chloro)(p-cymene)rutenium(II)]chloride] mediator complex and 1,2-diamino benzene (DAB) on a screen printing Pt electrode (1mm diameter). The electropolymerization was carried out at +0.7V for 45min in phosphate buffer (50mM, pH 7.0) which contained 14.0U/10mL polyphenole oxidase, 200mM DAB and 2.5mM Ru-mediator complex solutions. Measurement is based on the detection of the oxidation current of the Ru-mediator complex that related to the enzymatic reaction catalyzed by PPO at +0.65V. The phosphate buffer (50mM, pH 7.0 containing 0.1M KCl) and 30 degrees C were established as being the optimum working conditions. Under the optimum experimental conditions a linear calibration curve was obtained between 5 and 100microM catechol concentration. The detection limit of the biosensor is 2.385microM. In the characterization studies of the biosensor some parameters such as effect of Ru-mediator types on the biosensor response, substrate specificity, reproducibility and storage stability were studied. From the experiments, the average value (x), standard deviation (SD) and coefficient of variation (CV%) were found to be 48.75microM,+/-1.56microM, and 3.2% respectively for 50microM catechol standard. PMID:19783226

Akyilmaz, Erol; Kozgus, Ozge; Türkmen, Hayati; Cetinkaya, Bekir

2010-06-01

150

Monoacylcadaverines as substrates for both monoamine oxidase and diamine oxidase; low rates of activity  

Microsoft Academic Search

Summary Monoacetylcadaverine and monopropionylcadaverine were found to be substrates for both rat liver monoamine oxidase and hog kidney diamine oxidase, but all the Km-values for the oxidases were very high. The amines were common substrates for type A and type B monoamine oxidase.

O. Suzuki; T. Matsumoto; M. Oya; Y. Katsumata; M. Stepita-Klauco

1980-01-01

151

Rice cationic peroxidase accumulates in xylem vessels during incompatible interactions with Xanthomonas oryzae pv oryzae.  

PubMed

A cationic peroxidase, PO-C1 (molecular mass 42 kD, isoelectric point 8.6), which is induced in incompatible interactions between the vascular pathogen Xanthomonas oryzae pv oryzae and rice (Oryza sativa L.), was purified. Amino acid sequences from chemically cleaved fragments of PO-C1 exhibited a high percentage of identity with deduced sequences of peroxidases from rice, barley, and wheat. Polyclonal antibodies were raised to an 11-amino acid oligopeptide (POC1a) that was derived from a domain where the sequence of the cationic peroxidase diverged from other known peroxidases. The anti-POC1a antibodies reacted only with a protein of the same mobility as PO-C1 in extracellular and guttation fluids from plants undergoing incompatible responses collected at 24 h after infection. In the compatible responses, the antibodies did not detect PO-C1 until 48 h after infection. Immunoelectron microscopy was used to demonstrate that PO-C1 accumulated within the apoplast of mesophyll cells and within the cell walls and vessel lumen of xylem elements of plants undergoing incompatible interactions. PMID:7770527

Young, S A; Guo, A; Guikema, J A; White, F F; Leach, J E

1995-04-01

152

Rice cationic peroxidase accumulates in xylem vessels during incompatible interactions with Xanthomonas oryzae pv oryzae.  

PubMed Central

A cationic peroxidase, PO-C1 (molecular mass 42 kD, isoelectric point 8.6), which is induced in incompatible interactions between the vascular pathogen Xanthomonas oryzae pv oryzae and rice (Oryza sativa L.), was purified. Amino acid sequences from chemically cleaved fragments of PO-C1 exhibited a high percentage of identity with deduced sequences of peroxidases from rice, barley, and wheat. Polyclonal antibodies were raised to an 11-amino acid oligopeptide (POC1a) that was derived from a domain where the sequence of the cationic peroxidase diverged from other known peroxidases. The anti-POC1a antibodies reacted only with a protein of the same mobility as PO-C1 in extracellular and guttation fluids from plants undergoing incompatible responses collected at 24 h after infection. In the compatible responses, the antibodies did not detect PO-C1 until 48 h after infection. Immunoelectron microscopy was used to demonstrate that PO-C1 accumulated within the apoplast of mesophyll cells and within the cell walls and vessel lumen of xylem elements of plants undergoing incompatible interactions. PMID:7770527

Young, S A; Guo, A; Guikema, J A; White, F F; Leach, J E

1995-01-01

153

Draft Genome Sequence of Lactobacillus oryzae Strain SG293T.  

PubMed

We report the 1.86-Mb draft genome and annotation of Lactobacillus oryzae SG293(T) isolated from fermented rice grains. This genome information may provide further insights into the mechanisms underlying the fermentation of rice grains. PMID:25169865

Tanizawa, Yasuhiro; Fujisawa, Takatomo; Mochizuki, Takako; Kaminuma, Eli; Nakamura, Yasukazu; Tohno, Masanori

2014-01-01

154

21 CFR 173.130 - Carbohydrase derived from Rhizopus oryzae.  

Code of Federal Regulations, 2013 CFR

...CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Enzyme Preparations and Microorganisms § 173.130 Carbohydrase derived from Rhizopus oryzae. Carbohydrase from Rhizopus...

2013-04-01

155

21 CFR 173.130 - Carbohydrase derived from Rhizopus oryzae.  

Code of Federal Regulations, 2011 CFR

...CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Enzyme Preparations and Microorganisms § 173.130 Carbohydrase derived from Rhizopus oryzae. Carbohydrase from Rhizopus...

2011-04-01

156

21 CFR 173.130 - Carbohydrase derived from Rhizopus oryzae.  

Code of Federal Regulations, 2012 CFR

...CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Enzyme Preparations and Microorganisms § 173.130 Carbohydrase derived from Rhizopus oryzae. Carbohydrase from Rhizopus...

2012-04-01

157

21 CFR 173.130 - Carbohydrase derived from Rhizopus oryzae.  

Code of Federal Regulations, 2010 CFR

...CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Enzyme Preparations and Microorganisms § 173.130 Carbohydrase derived from Rhizopus oryzae. Carbohydrase from Rhizopus...

2010-04-01

158

21 CFR 173.130 - Carbohydrase derived from Rhizopus oryzae.  

...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Enzyme Preparations and Microorganisms § 173.130 Carbohydrase derived from Rhizopus oryzae. Carbohydrase from Rhizopus...

2014-04-01

159

Original article Variation for polyphenol oxidase activity  

E-print Network

Original article Variation for polyphenol oxidase activity in stems of Medicago species Michele) Abstract - Polyphenol oxidase (PPO) activity was detected in stems of both glandular-haired and glabrous; Inra/Elsevier, Paris.) insect resistance / Medicago spp / Leguminosae / polyphenol oxidase RĂŠsumĂŠ - L

Paris-Sud XI, UniversitĂŠ de

160

GLUCOSE OXIDASE REDUCES OXIDATION IN FROZEN SHRIMP  

E-print Network

role oxygen can have during storage of foods (Scott, 1958). Glucose oxidase-catalase preparations are used to carry out the net reaction: 2 glucose + oxygen glucose oxidase > 2 gluconic acid. catalase of glucose oxidase -catalase would probably be more obvious in shrimp, which were packed in transparent bags

161

Recognition of Ferric Catecholates by FepA  

PubMed Central

Escherichia coli FepA transports certain catecholate ferric siderophores, but not others, nor any noncatecholate compounds. Direct binding and competition experiments demonstrated that this selectivity originates during the adsorption stage. The synthetic tricatecholate Fe-TRENCAM bound to FepA with 50- to 100-fold-lower affinity than Fe-enterobactin (FeEnt), despite an identical metal center, and Fe-corynebactin only bound at much higher concentrations. Neither Fe-agrobactin nor ferrichrome bound at all, even at concentrations 106-fold above the Kd. Thus, FepA only adsorbs catecholate iron complexes, and it selects FeEnt among even its close homologs. We used alanine scanning mutagenesis to study the contributions of surface aromatic residues to FeEnt recognition. Although not apparent from crystallography, aromatic residues in L3, L5, L7, L8, and L10 affected FepA's interaction with FeEnt. Among 10 substitutions that eliminated aromatic residues, Kd increased as much as 20-fold (Y481A and Y638A) and Km increased as much as 400-fold (Y478), showing the importance of aromaticity around the pore entrance. Although many mutations equally reduced binding and transport, others caused greater deficiencies in the latter. Y638A and Y478A increased Km 10- and 200-fold more, respectively, than Kd. N-domain loop deletions created the same phenotype: ?60-67 (in NL1) and ?98-105 (in NL2) increased Kd 10- to 20-fold but raised Km 500- to 700-fold. W101A (in NL2) had little effect on Kd but increased Km 1,000-fold. These data suggested that the primary role of the N terminus is in ligand uptake. Fluorescence and radioisotopic experiments showed biphasic release of FeEnt from FepA. In spectroscopic determinations, koff1 was 0.03/s and koff2 was 0.003/s. However, FepAY272AF329A did not manifest the rapid dissociation phase, corroborating the role of aromatic residues in the initial binding of FeEnt. Thus, the ?-barrel loops contain the principal ligand recognition determinants, and the N-domain loops perform a role in ligand transport. PMID:15150246

Annamalai, Rajasekaran; Jin, Bo; Cao, Zhenghua; Newton, Salete M. C.; Klebba, Phillip E.

2004-01-01

162

Recognition of ferric catecholates by FepA.  

PubMed

Escherichia coli FepA transports certain catecholate ferric siderophores, but not others, nor any noncatecholate compounds. Direct binding and competition experiments demonstrated that this selectivity originates during the adsorption stage. The synthetic tricatecholate Fe-TRENCAM bound to FepA with 50- to 100-fold-lower affinity than Fe-enterobactin (FeEnt), despite an identical metal center, and Fe-corynebactin only bound at much higher concentrations. Neither Fe-agrobactin nor ferrichrome bound at all, even at concentrations 10(6)-fold above the Kd. Thus, FepA only adsorbs catecholate iron complexes, and it selects FeEnt among even its close homologs. We used alanine scanning mutagenesis to study the contributions of surface aromatic residues to FeEnt recognition. Although not apparent from crystallography, aromatic residues in L3, L5, L7, L8, and L10 affected FepA's interaction with FeEnt. Among 10 substitutions that eliminated aromatic residues, Kd increased as much as 20-fold (Y481A and Y638A) and Km increased as much as 400-fold (Y478), showing the importance of aromaticity around the pore entrance. Although many mutations equally reduced binding and transport, others caused greater deficiencies in the latter. Y638A and Y478A increased Km 10- and 200-fold more, respectively, than Kd. N-domain loop deletions created the same phenotype: Delta60-67 (in NL1) and Delta98-105 (in NL2) increased Kd 10- to 20-fold but raised Km 500- to 700-fold. W101A (in NL2) had little effect on Kd but increased Km 1,000-fold. These data suggested that the primary role of the N terminus is in ligand uptake. Fluorescence and radioisotopic experiments showed biphasic release of FeEnt from FepA. In spectroscopic determinations, k(off1) was 0.03/s and k(off2) was 0.003/s. However, FepAY272AF329A did not manifest the rapid dissociation phase, corroborating the role of aromatic residues in the initial binding of FeEnt. Thus, the beta-barrel loops contain the principal ligand recognition determinants, and the N-domain loops perform a role in ligand transport. PMID:15150246

Annamalai, Rajasekaran; Jin, Bo; Cao, Zhenghua; Newton, Salete M C; Klebba, Phillip E

2004-06-01

163

Semidwarf (sd-1), “green revolution” rice, contains a defective gibberellin 20-oxidase gene  

PubMed Central

The introduction of semidwarf rice (Oryza sativa L.) led to record yield increases throughout Asia in the 1960s. The major semidwarfing allele, sd-1, is still extensively used in modern rice cultivars. The phenotype of sd-1 is consistent with dwarfism that results from a deficiency in gibberellin (GA) plant growth hormones. We propose that the semidwarf (sd-1) phenotype is the result of a deficiency of active GAs in the elongating stem arising from a defective 20-oxidase GA biosynthetic enzyme. Sequence data from the rice genome was combined with previous mapping studies to locate a putative GA 20-oxidase gene (Os20ox2) at the predicted map location of sd-1 on chromosome 1. Two independent sd-1 alleles contained alterations within Os20ox2: a deletion of 280 bp within the coding region of Os20ox2 was predicted to encode a nonfunctional protein in an indica type semidwarf (Doongara), whereas a substitution in an amino acid residue (Leu-266) that is highly conserved among dioxygenases could explain loss of function of Os20ox2 in a japonica semidwarf (Calrose76). The quantification of GAs in elongating stems by GC-MS showed that the initial substrate of GA 20-oxidase activity (GA53) accumulated, whereas the content of the major product (GA20) and of bioactive GA1 was lower in semidwarf compared with tall lines. We propose that the Os20ox2 gene corresponds to the sd-1 locus. PMID:12077303

Spielmeyer, Wolfgang; Ellis, Marc H.; Chandler, Peter M.

2002-01-01

164

NADPH oxidases regulate septin-mediated cytoskeletal remodeling during plant infection by the rice blast fungus  

PubMed Central

The rice blast fungus Magnaporthe oryzae infects plants with a specialized cell called an appressorium, which uses turgor to drive a rigid penetration peg through the rice leaf cuticle. Here, we show that NADPH oxidases (Nox) are necessary for septin-mediated reorientation of the F-actin cytoskeleton to facilitate cuticle rupture and plant cell invasion. We report that the Nox2–NoxR complex spatially organizes a heteroligomeric septin ring at the appressorium pore, required for assembly of a toroidal F-actin network at the point of penetration peg emergence. Maintenance of the cortical F-actin network during plant infection independently requires Nox1, a second NADPH oxidase, which is necessary for penetration hypha elongation. Organization of F-actin in appressoria is disrupted by application of antioxidants, whereas latrunculin-mediated depolymerization of appressorial F-actin is competitively inhibited by reactive oxygen species, providing evidence that regulated synthesis of reactive oxygen species by fungal NADPH oxidases directly controls septin and F-actin dynamics. PMID:23382235

Ryder, Lauren S.; Dagdas, Yasin F.; Mentlak, Thomas A.; Kershaw, Michael J.; Thornton, Christopher R.; Schuster, Martin; Chen, Jisheng; Wang, Zonghua; Talbot, Nicholas J.

2013-01-01

165

Improving Pharmaceutical Protein Production in Oryza sativa  

PubMed Central

Application of plant expression systems in the production of recombinant proteins has several advantages, such as low maintenance cost, absence of human pathogens, and possession of complex post-translational glycosylation capabilities. Plants have been successfully used to produce recombinant cytokines, vaccines, antibodies, and other proteins, and rice (Oryza sativa) is a potential plant used as recombinant protein expression system. After successful transformation, transgenic rice cells can be either regenerated into whole plants or grown as cell cultures that can be upscaled into bioreactors. This review summarizes recent advances in the production of different recombinant protein produced in rice and describes their production methods as well as methods to improve protein yield and quality. Glycosylation and its impact in plant development and protein production are discussed, and several methods of improving yield and quality that have not been incorporated in rice expression systems are also proposed. Finally, different bioreactor options are explored and their advantages are analyzed. PMID:23615467

Kuo, Yu-Chieh; Tan, Chia-Chun; Ku, Jung-Ting; Hsu, Wei-Cho; Su, Sung-Chieh; Lu, Chung-An; Huang, Li-Fen

2013-01-01

166

Improving Pharmaceutical Protein Production in Oryza sativa.  

PubMed

Application of plant expression systems in the production of recombinant proteins has several advantages, such as low maintenance cost, absence of human pathogens, and possession of complex post-translational glycosylation capabilities. Plants have been successfully used to produce recombinant cytokines, vaccines, antibodies, and other proteins, and rice (Oryza sativa) is a potential plant used as recombinant protein expression system. After successful transformation, transgenic rice cells can be either regenerated into whole plants or grown as cell cultures that can be upscaled into bioreactors. This review summarizes recent advances in the production of different recombinant protein produced in rice and describes their production methods as well as methods to improve protein yield and quality. Glycosylation and its impact in plant development and protein production are discussed, and several methods of improving yield and quality that have not been incorporated in rice expression systems are also proposed. Finally, different bioreactor options are explored and their advantages are analyzed. PMID:23615467

Kuo, Yu-Chieh; Tan, Chia-Chun; Ku, Jung-Ting; Hsu, Wei-Cho; Su, Sung-Chieh; Lu, Chung-An; Huang, Li-Fen

2013-01-01

167

Catecholamines oxidation by xanthine oxidase  

Microsoft Academic Search

Dopamine and structurally related catecholamines in the presence of hydrogen peroxide are oxidized in vitro by xanthine oxidase producing the corresponding melanin pigments. The kinetic parameters of the reaction, measured as aminochrome formation, have been calculated. The rate of peroxidation depends on enzyme and hydrogen peroxide concentration. The optimum pH for the peroxidative activity of the enzyme is around 8.5.

Cesira Foppoli; Raffaella Coccia; Chiara Cini; Maria Anna Rosei

1997-01-01

168

Hypnotizability and Catechol-O-Methyltransferase (COMT) polymorphysms in Italians.  

PubMed

Higher brain dopamine content depending on lower activity of Catechol-O-Methyltransferase (COMT) in subjects with high hypnotizability scores (highs) has been considered responsible for their attentional characteristics. However, the results of the previous genetic studies on association between hypnotizability and the COMT single nucleotide polymorphism (SNP) rs4680 (Val(158)Met) were inconsistent. Here, we used a selective genotyping approach to re-evaluate the association between hypnotizability and COMT in the context of a two-SNP haplotype analysis, considering not only the Val(158)Met polymorphism, but also the closely located rs4818 SNP. An Italian sample of 53 highs, 49 low hypnotizable subjects (lows), and 57 controls, were genotyped for a segment of 805 bp of the COMT gene, including Val(158)Met and the closely located rs4818 SNP. Our selective genotyping approach had 97.1% power to detect the previously reported strongest association at the significance level of 5%. We found no evidence of association at the SNP, haplotype, and diplotype levels. Thus, our results challenge the dopamine-based theory of hypnosis and indirectly support recent neuropsychological and neurophysiological findings reporting the lack of any association between hypnotizability and focused attention abilities. PMID:24431998

Presciuttini, Silvano; Gialluisi, Alessandro; Barbuti, Serena; Curcio, Michele; Scatena, Fabrizio; Carli, Giancarlo; Santarcangelo, Enrica L

2014-01-01

169

Hypnotizability and Catechol-O-Methyltransferase (COMT) polymorphysms in Italians  

PubMed Central

Higher brain dopamine content depending on lower activity of Catechol-O-Methyltransferase (COMT) in subjects with high hypnotizability scores (highs) has been considered responsible for their attentional characteristics. However, the results of the previous genetic studies on association between hypnotizability and the COMT single nucleotide polymorphism (SNP) rs4680 (Val158Met) were inconsistent. Here, we used a selective genotyping approach to re-evaluate the association between hypnotizability and COMT in the context of a two-SNP haplotype analysis, considering not only the Val158Met polymorphism, but also the closely located rs4818 SNP. An Italian sample of 53 highs, 49 low hypnotizable subjects (lows), and 57 controls, were genotyped for a segment of 805 bp of the COMT gene, including Val158Met and the closely located rs4818 SNP. Our selective genotyping approach had 97.1% power to detect the previously reported strongest association at the significance level of 5%. We found no evidence of association at the SNP, haplotype, and diplotype levels. Thus, our results challenge the dopamine-based theory of hypnosis and indirectly support recent neuropsychological and neurophysiological findings reporting the lack of any association between hypnotizability and focused attention abilities. PMID:24431998

Presciuttini, Silvano; Gialluisi, Alessandro; Barbuti, Serena; Curcio, Michele; Scatena, Fabrizio; Carli, Giancarlo; Santarcangelo, Enrica L.

2014-01-01

170

Pharmacogenomics: catechol O-methyltransferase to thiopurine S-methyltransferase.  

PubMed

1. Pharmacogenomics is the study of the role of inheritance in variation in the drug response phenotype-a phenotype that can vary from adverse drug reactions at one end of the spectrum to lack of therapeutic efficacy at the other. 2. The thiopurine S-methyltransferase (TPMT) genetic polymorphism represents one of the best characterized and most clinically relevant examples of pharmacogenomics. This polymorphism has also served as a valuable "model system" for studies of the ways in which variation in DNA sequence might influence function. 3. The discovery and characterization of the TPMT polymorphism grew directly out of pharmacogenomic studies of catechol O-methyltransferase (COMT), an enzyme discovered by Julius (Julie) Axelrod and his coworkers. 4. This review will outline the process by which common, functionally significant genetic polymorphisms for both COMT and TPMT were discovered and will use these two methyltransferase enzymes to illustrate general principles of pharmacogenomic research-both basic mechanistic and clinical translational research-principles that have been applied to a series of genes encoding methyltransferase enzymes. PMID:16807786

Weinshilboum, Richard M

2006-01-01

171

Substrate selectivity of monoamine oxidase A, monoamine oxidase B, diamine oxidase, and semicarbazide-sensitive amine oxidase in COS-1 expression systems.  

PubMed

The substrate selectivity of monoamine oxidase A (MAO-A), monoamine oxidase B (MAO-B), diamine oxidase (DAO), and semicarbazide-sensitive amine oxidase (SSAO) was investigated in the absence of chemical inhibitors using the COS-1 cells expressed with respective amine oxidase. Serotonin (5-hydroxytryptamine), 1-methylhistamine, and histamine were preferentially oxidized by MAO-A, SSAO, and DAO, respectively, at a low substrate concentration. In contrast, benzylamine, tyramine, and beta-phenylethylamine served as substrates for all of MAO-A, MAO-B, and SSAO. Each amine oxidase showed broad substrate selectivity at a high substrate concentration. The cross-inhibition was remarkable in MAO-A and MAO-B, especially in MAO-A, but not in SSAO and DAO. A study of the substrate selectivity of amine oxidases should include consideration of the effects of substrate concentration and specific chemical inhibitors. PMID:17142964

Ochiai, Yoshinori; Itoh, Kunio; Sakurai, Eiichi; Adachi, Mayuko; Tanaka, Yorihisa

2006-12-01

172

The influence of metabolism on the genotoxicity of catechol estrogens in three cultured cell lines.  

PubMed

The 2- and 4-hydroxy metabolites of 17beta-estradiol (E2) and estrone (E1) are important for E2-mediated carcinogenesis due to the formation of genotoxic ortho-quinone metabolites. To assess the importance of metabolic conjugation for their genotoxicity, the DNA strand-breaking activity of the four catechol estrogens was determined in three cell lines with different activities of catechol-O-methyltransferase (COMT) and UDP-glucuronosyltransferase (UGT). Most DNA strand breaks were observed in V79 cells, which lack these metabolic activities. 2- and 4-hydroxy-E2 were 2.5 times more genotoxic than 2- and 4-hydroxy-E1. MCF-7 cells exhibit COMT activity, and the incidence of DNA strand breaks decreased with increasing methylation; only the 4-hydroxy metabolites of E1 and E2, which were poor substrates of COMT, exhibited low genotoxicity. HepG2 cells converted the catechol and methoxy metabolites of E2 to the respective E1 metabolites by 17beta-hydroxysteroid dehydrogenase (HSD). Moreover, methylation and glucuronidation took place. Only 4-hydroxy-E1 elicited a weak genotoxic response in these cells. The extensive metabolism in HepG2 cells is proposed to account for the failure of catechol estrogens to induce DNA strand breaks. Thus, metabolism by COMT and UGT and, to a minor extent, by HSD is a major determinant for the genotoxicity of catechol estrogens in target cells. PMID:18618478

Gerstner, Silke; Glasemann, Dörte; Pfeiffer, Erika; Metzler, Manfred

2008-07-01

173

In planta gene expression analysis of Xanthomonas oryzae pathovar oryzae, African strain MAI1  

PubMed Central

Background Bacterial leaf blight causes significant yield losses in rice crops throughout Asia and Africa. Although both the Asian and African strains of the pathogen, Xanthomonas oryzae pv. oryzae (Xoo), induce similar symptoms, they are nevertheless genetically different, with the African strains being more closely related to the Asian X. oryzae pv. oryzicola (Xoc). Results Changes in gene expression of the African Xoo strain MAI1 in the susceptible rice cultivar Nipponbare were profiled, using an SSH Xoo DNA microarray. Microarray hybridization was performed comparing bacteria recovered from plant tissues at 1, 3, and 6 days after inoculation (dai) with bacteria grown in vitro. A total of 710 bacterial genes were found to be differentially expressed, with 407 up-regulated and 303 down-regulated. Expression profiling indicated that less than 20% of the 710 bacterial transcripts were induced in the first 24 h after inoculation, whereas 63% were differentially expressed at 6 dai. The 710 differentially expressed genes were one-end sequenced. 535 sequences were obtained from which 147 non-redundant sequences were identified. Differentially expressed genes were related to metabolism, secretion and transport, pathogen adherence to plant tissues, plant cell-wall degradation, IS elements, and virulence. In addition, various other genes encoding proteins with unknown function or showing no similarity to other proteins were also induced. The Xoo MAI1 non-redundant set of sequences was compared against several X. oryzae genomes, revealing a specific group of genes that was present only in MAI1. Numerous IS elements were also found to be differentially expressed. Quantitative real-time PCR confirmed 86% of the identified profile on a set of 14 genes selected according to the microarray analysis. Conclusions This is the first report to compare the expression of Xoo genes in planta across different time points during infection. This work shows that as-yet-unidentified and potentially new virulence factors are appearing in an emerging African pathogen. It also confirms that African Xoo strains do differ from their Asian counterparts, even at the transcriptional level. PMID:20540733

2010-01-01

174

A hyperactive cobalt-substituted extradiol-cleaving catechol dioxygenase.  

PubMed

Homoprotocatechuate 2,3-dioxygenase from Brevibacterium fuscum (HPCD) has an Fe(II) center in its active site that can be replaced with Mn(II) or Co(II). Whereas Mn-HPCD exhibits steady-state kinetic parameters comparable to those of Fe-HPCD, Co-HPCD behaves somewhat differently, exhibiting significantly higher [Formula: see text] and k (cat). The high activity of Co-HPCD is surprising, given that cobalt has the highest standard M(III/II) redox potential of the three metals. Comparison of the X-ray crystal structures of the resting and substrate-bound forms of Fe-HPCD, Mn-HPCD, and Co-HPCD shows that metal substitution has no effect on the local ligand environment, the conformational integrity of the active site, or the overall protein structure, suggesting that the protein structure does not differentially tune the potential of the metal center. Analysis of the steady-state kinetics of Co-HPCD suggests that the Co(II) center alters the relative rate constants for the interconversion of intermediates in the catalytic cycle but still allows the dioxygenase reaction to proceed efficiently. When compared with the kinetic data for Fe-HPCD and Mn-HPCD, these results show that dioxygenase catalysis can proceed at high rates over a wide range of metal redox potentials. This is consistent with the proposed mechanism in which the metal mediates electron transfer between the catechol substrate and O(2) to form the postulated [M(II)(semiquinone)superoxo] reactive species. These kinetic differences and the spectroscopic properties of Co-HPCD provide new tools with which to explore the unique O(2) activation mechanism associated with the extradiol dioxygenase family. PMID:21153851

Fielding, Andrew J; Kovaleva, Elena G; Farquhar, Erik R; Lipscomb, John D; Que, Lawrence

2011-02-01

175

Catechol-O-methyltransferase, dopamine, and sleep-wake regulation.  

PubMed

Sleep and sleep disorders are complex and highly variable phenotypes regulated by many genes and environment. The catechol-O-methyltransferase (COMT) gene is an interesting candidate, being one of the major mammalian enzymes involved in the catabolism of catecholamines. The activity of COMT enzyme is genetically polymorphic due to a guanine-to-adenine transition at codon 158, resulting in a valine (Val) to methionine (Met) substitution. Individuals homozygous for the Val allele show higher COMT activity, and lower dopaminergic signaling in prefrontal cortex (PFC) than subjects homozygous for the Met allele. Since COMT has a crucial role in metabolising dopamine, it was suggested that the common functional polymorphism in the COMT gene impacts on cognitive function related to PFC, sleep-wake regulation, and potentially on sleep pathologies. The COMT Val158Met polymorphism may predict inter-individual differences in brain electroencephalography (EEG) alpha oscillations and recovery processes resulting from partial sleep loss in healthy individuals. The Val158Met polymorphism also exerts a sexual dimorphism and has a strong effect on objective daytime sleepiness in patients with narcolepsy-cataplexy. Since the COMT enzyme inactivates catecholamines, it was hypothesized that the response to stimulant drugs differs between COMT genotypes. Modafinil maintained executive functioning performance and vigilant attention throughout sleep deprivation in subjects with Val/Val genotype, but less in those with Met/Met genotype. Also, homozygous Met/Met patients with narcolepsy responded to lower doses of modafinil compared to Val/Val carriers. We review here the critical role of the common functional COMT gene polymorphism, COMT enzyme activity, and the prefrontal dopamine levels in the regulation of sleep and wakefulness in normal subjects, in narcolepsy and other sleep-related disorders, and its impact on the response to psychostimulants. PMID:25466290

Dauvilliers, Yves; Tafti, Mehdi; Landolt, Hans Peter

2014-10-27

176

Regulation of jasmonic acid biosynthesis by silicon application during physical injury to Oryza sativa L.  

PubMed

We investigated the effects of silicon (Si) application on rice plants (Oryza sativa L.) and its responses in the regulation of jasmonic acid (JA) during wounding stress. Endogenous JA was significantly higher in wounded rice plants than in non-wounded. In contrast, Si treatment significantly reduced JA synthesis as compared to non-Si applications under wounding stress. mRNA expression of O. sativa genes showed down-regulation of lipoxygenase, allene oxide synthase 1, allene oxide synthase 2, 12-oxophytodienoate reductase 3, and allene oxide cyclase upon Si application and wounding stress as compared to non-Si-treated wounded rice plants. The physical injury-induced-oxidative stress was modulated by Si treatments, which resulted in higher catalase, peroxidase, and polyphenol oxidase activities as compared with non-Si-treated plants under wounding stress. The higher Si accumulation in rice plants also reduced the level of lipid peroxidation, which helped the rice plants to protect it from wounding stress. In conclusion, Si accumulation in rice plants mitigated the adverse effects of wounding through regulation of antioxidants and JA. PMID:24840865

Kim, Yoon-Ha; Khan, Abdul Latif; Waqas, Muhammad; Jeong, Hee-Jeong; Kim, Duk-Hwan; Shin, Jeong Sheop; Kim, Jong-Guk; Yeon, Myung-Hun; Lee, In-Jung

2014-07-01

177

Aqueous extracts of Rhizopus oryzae induced nitric oxide production in rat hepatocyte cell line RLN-10.  

PubMed

Aqueous extracts of Rhizopus oryzae (Aq-ROU) have a broad range of physiological activity. Here we identified a new physiological effect of Aq-ROU in rat hepatocyte cell line RLN-10. Aq-ROU induced the accumulation of nitrite, a stable metabolite nitric oxide (NO), in cell culture medium and induced potent diaminofluorescein-FM diacetate staining in the cells. Real-time reverse transcriptase (RT)-PCR analysis showed marked inducible NO synthase gene expression. Additionally, markedly enhanced expression of p22(phox) and temporally increased expression of NADPH oxidase1 indicated that superoxide was produced. Nuclear translocation of nuclear factor-kappa (NF-?) B p65 increased remarkably following Aq-ROU and following lipopolysaccharide treatment, a potent activator of NF-?B. Ammonium pyrrolidine-1-carbodithioate, an inhibitor of NF-?B, inhibited NO production following Aq-ROU treatment. Our data indicate that Aq-ROU induces NO production and potentially the production of superoxide, which may contribute to the broad range of physiological effects observed for Aq-ROU ingested by animals. PMID:23832357

Suzuki, Takehito; Uchida, Mayuko; Takeda, Yuji; Mori, Chiemi; Onuki, Atsushi; Miyazaki, Yoko; Onda, Ken; Ushikoshi, Setsuo; Shitori, Kotaro; Tanaka, Kazuaki; Morita, Hidetoshi; Takizawa, Tatsuya

2013-01-01

178

ISOLATION AND CHARACTERIZATION OF A SECOND GLUCOAMYLASE WITHOUT A STARCH BINDING DOMAIN FROM RHIZOPUS ORYZAE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Work with Rhizopus oryzae previously suggested that this filamentous fungus only had one glucoamylase. We demonstrate in this study that some R. oryzae strains contain multiple glucoamylase genes with differential regulation. The existence of the two unique, amy genes in R. oryzae NRRL 395, a type...

179

Identification and QTL mapping of blast resistance in wild Oryza species  

Technology Transfer Automated Retrieval System (TEKTRAN)

Leaf blast disease of rice (Oryza sativa L.) caused by Magnaporthe oryzae B. Couch is one of the most devastating rice fungal diseases worldwide. Wild relatives of rice (Oryza spp.) may contain novel genes for biotic and abiotic stress resistance lost during domestication. A collection of 67 wild ...

180

Comparison and analysis of the genomes of two Aspergillus oryzae strains.  

PubMed

A. oryzae 3.042 (China) and A. oryzae RIB40 (Japan) used for soy sauce fermentation show some regional differences. We sequenced the genome of A. oryzae 3.042 and compared it to A. oryzae RIB40 in an attempt to understand why different features are shown by these two A. oryzae strains. We predict 11,399 protein-coding genes in A. oryzae 3.042. The genomes of these two A. oryzae strains are collinear revealed by MUMmer analysis, indicating that the differences are not obvious between them. Several strain-specific genes of two strains are identified by genome sequences' comparison, and they are classified into some groups, which have the relationship with cell growth, cellular response and regulation, resistance, energy metabolism, salt tolerance, and flavor formation. A. oryzae 3.042 showed stronger potential for mycelial growth and environmental stress resistance, such as the genes of chitinase and quinone reductase. Some genes unique to A. oryzae RIB40 were related to energy metabolism and salt tolerance, especially genes for Na(+) and K(+) transport, while others were associated with signal transduction and flavor formation. The genome sequence of A. oryzae 3.042 will facilitate the identification of the genetic basis of traits in A. oryzae 3.042, and accelerate our understanding of the different genetic traits of the two A. oryzae strains. PMID:23889147

Zhao, Guozhong; Yao, Yunping; Chen, Wei; Cao, Xiaohong

2013-08-14

181

Reduced expression of glycolate oxidase leads to enhanced disease resistance in rice  

PubMed Central

Glycolate oxidase (GLO) is a key enzyme in photorespiration, catalyzing the oxidation of glycolate to glyoxylate. Arabidopsis GLO is required for nonhost defense responses to Pseudomonas syringae and for tobacco Pto/AvrPto-mediated defense responses. We previously described identification of rice GLO1 that interacts with a glutaredoxin protein, which in turn interacts with TGA transcription factors. TGA transcription factors are well known to participate in NPR1/NH1-mediated defense signaling, which is crucial to systemic acquired resistance in plants. Here we demonstrate that reduction of rice GLO1 expression leads to enhanced resistance to Xanthomonas oryzae pv oryzae (Xoo). Constitutive silencing of GLO1 leads to programmed cell death, resulting in a lesion-mimic phenotype and lethality or reduced plant growth and development, consistent with previous reports. Inducible silencing of GLO1, employing a dexamethasone-GVG (Gal4 DNA binding domain-VP16 activation domain-glucocorticoid receptor fusion) inducible system, alleviates these detrimental effects. Silencing of GLO1 results in enhanced resistance to Xoo, increased expression of defense regulators NH1, NH3, and WRKY45, and activation of PR1 expression. PMID:23638363

Chern, Mawsheng; Bai, Wei; Chen, Xuewei; Canlas, Patrick E.

2013-01-01

182

Lactobacillus oryzae sp. nov., isolated from fermented rice grain (Oryza sativa L. subsp. japonica).  

PubMed

The taxonomic position of three Lactobacillus-like micro-organisms (strains SG293(T), SG296 and SG310) isolated from fermented rice grain (Oryza sativa L. subsp. japonica) in Japan was investigated. These heterofermentative lactic acid bacteria were Gram-stain-positive, rod-shaped, facultatively anaerobic, non-motile, non-spore-forming and did not show catalase activity. 16S rRNA gene sequence analysis of strain SG293(T) revealed that the type strains of Lactobacillus malefermentans (98.3 %), Lactobacillus odoratitofui (96.2 %), Lactobacillus similis (96.1 %), Lactobacillus kimchicus (96.1 %), Lactobacillus paracollinoides (95.9 %) and Lactobacillus collinoides (95.7 %) were the closest neighbours. Additional phylogenetic analysis on the basis of pheS and rpoA gene sequences, as well as biochemical and physiological characteristics, indicated that these three strains were members of the genus Lactobacillus and that the novel isolates had a unique taxonomic position. The predominant cellular fatty acids were C18 : 1?9c and C19 : 1 cyclo 9,10. Because low DNA-DNA hybridization values among the isolates and Lactobacillus malefermentans JCM 12497(T) were observed, it is proposed that these unidentified isolates be classified as a novel species of the genus Lactobacillus, Lactobacillus oryzae sp. nov. The type strain is SG293(T) (= JCM 18671(T) = DSM 26518(T)). PMID:23378109

Tohno, Masanori; Kitahara, Maki; Irisawa, Tomohiro; Inoue, Hidehiko; Uegaki, Ryuichi; Ohkuma, Moriya; Tajima, Kiyoshi

2013-08-01

183

Baroreceptor reflex-linked changes in catechol metabolism in the rat rostral ventrolateral medulla.  

PubMed Central

1. Using in vivo voltammetry, this study relates catecholamine metabolism within the rat rostral ventrolateral medulla to the level of mean arterial pressure (MAP) under halothane anaesthesia. 2. A vasopressor region was circumscribed with electrical stimulations in an area located 1000-1700 microns rostral to the obex. A catechol signal was then ascertained within this area. The recording site was surrounded with phenyl-N-methyl-ethanolamine transferase immuno-positive cell bodies. 3. Three levels of decrease of arterial pressure were induced with nitroprusside infusion: -15, -35 and -55 mmHg (n = 5 in each group) from baseline for 30 min. This led to increases in the catechol signal which were inversely related to the degree of hypotension (P < 10(-4) vs. saline for the 35 and 55 mmHg groups, P < 0.05 for the 35 mmHg group as compared to the 15 and 55 mmHg groups following recovery from hypotension). 4. Following sino-aortic deafferentation, nitroprusside-induced hypotension (-35 mmHg) did not lead to any change in the catechol signal in the rostral ventrolateral medulla (n = 5). Furthermore, controlled hypotension induced in intact rats did not evoke any change in the catechol signal recorded in a dopaminergic area of the midbrain, the ventral tegmental area (A10 area; n = 5). 5. An infusion of phenylephrine increased MAP by 35 mmHg from a baseline pressure of 105 mmHg for 30 min and evoked a non-significant decrease in the catechol signal (n = 5). In another group of rats a lower baseline pressure (80 mmHg) was stabilized (n = 5) with a higher concentration of halothane. An identical increment in pressure was then produced by a phenylephrine infusion and led to a significant reduction in the catechol signal (P < 0.05 vs. saline under similar conditions; n = 5). 6. The new findings of this study are that the level of activity of the metabolism of catecholamine in the rostral ventrolateral medulla (i) is continuously related to the level of arterial pressure, (ii) functions close to its resting level under baseline conditions and is primarily engaged during hypotension and (iii) is baroreflex linked. 7. Given the lack of direct evidence for a link between unit activity and catechol metabolism, these changes in catechol activity, recorded continuously in vivo next to adrenergic cell bodies, may represent the biochemical-specific counterpart of changes in the level of electrical unitary activity of presumed adrenergic cardiovascular medullospinal sympathoexcitatory neurons. Therefore, it provides evidence that adrenaline-synthesizing neurons in the rostral ventrolateral medulla respond to baroreceptor inputs. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8271225

Rentero, N; Kitahama, K; Quintin, L

1993-01-01

184

Synthesis, molecular structure and magnetic properties of a rhenium(IV) compound with catechol  

NASA Astrophysics Data System (ADS)

A novel Re(IV) complex containing catechol as ligand has been prepared and characterized. The crystal structure of (HNEt 3)(NBu 4)[ReCl 4(cat)]ˇH 2cat was determined. The rhenium ion presents a distorted octahedral geometry, being bonded to a bidentate catecholate group and four chloride anions. The magnetic properties of the complex were studied, a /2 D/ (the energy gap between ą3/2 and ą1/2 Kramers doublets) value of 190(10) cm -1. This is the largest /2 D/ value reported for Re(IV) up to now.

Cuevas, A.; Geis, L.; Pintos, V.; Chiozzone, R.; Sanchíz, J.; Hummert, M.; Schumann, H.; Kremer, C.

2009-03-01

185

Polyphenol oxidase from wheat bran is a serpin.  

PubMed

Polyphenol oxidase (PPO; EC 1.10.3.2) was isolated from wheat bran by a procedure that included ammonium sulfate fractionation, batch adsorption by DEAE-cellulofine, CM-cellulofine column chromatography, DEAE-cellulofine column chromatography, preparative isoelectric focusing, adsorption on the membrane of a Vivapure Q Maxi H spin column, and heat treatment. These procedures led to 150-fold purification with 4.2% recovery. The PPO was homogeneous by SDS/PAGE. The relative molecular weight of the PPO was estimated to be 37,000 based on its mobility in SDS/PAGE. The isoelectric point of the PPO was 4.4. The K(m) values of the PPO for caffeic acid, chlorogenic acid, pyrocatechol, 4-methyl catechol and l-DOPA as substrates were 0.077, 0.198, 1.176, 1.667 and 4.545 mM. The PPO was strongly inhibited by tropolone. The K(i) value for tropolone is 2.2 x 10(-7) M. The sequence of the 15 N-terminal amino-acid residues was determined to be ATDVRLSIAHQTRFA, which was identical to those of serpin from Triticum aestivum and protein Z from Hordeum vulgare. The PPO strongly inhibited the activity of trypsin, which is an enzyme of serine proteases; 50% inhibition was observed with 1.5 x 10(-7) M PPO. The K(i) value for PPO is 2.3 x 10(-8) M. The wheat bran PPO should be a very important protein for protecting wheat against disease, virus, insect and herbivore damages by both the activities of PPO and protease inhibitor. PMID:18506224

Yamasaki, Yoshiki; Konno, Haruyoshi; Noda, Kazuhiko

2008-01-01

186

Activation of Polyphenol Oxidase of Chloroplasts  

Microsoft Academic Search

Polyphenol oxidase ofleaves islocated mainlyinchloro- plasts isolated bydifferential orsucrose density gradient cen- trifugation. Thisactivity ispartofthelamellar structure that isnotlost onrepeated washing oftheplastids. Theoxidase ac- tivity wasstable during prolonged storage oftheparticles at 4C or-18C.TheKm (dihydroxyphenylalanine) forspinach leafpolyphenol oxidase was7mM byaspectrophotometric as- sayand2 mM bythemanometric assay. Polyphenol oxidase activity intheleafperoxisomal fraction, afterisopycnic cen- trifugation onalinear sucrose gradient, didnotcoincide with theperoxisomal enzymesbutwasattributed toproplastids at

N. E. Tolbert

1973-01-01

187

Multicopper Oxidase-3 Is a Laccase Associated with the Peritrophic Matrix of Anopheles gambiae  

PubMed Central

The multicopper oxidase (MCO) family of enzymes includes laccases, which oxidize a broad range of substrates including polyphenols and phenylendiamines; ferroxidases, which oxidize ferrous iron; and several other oxidases with specific substrates such as ascorbate, bilirubin or copper. The genome of Anopheles gambiae, a species of mosquito, encodes five putative multicopper oxidases. Of these five, only AgMCO2 has known enzymatic and physiological functions: it is a highly conserved laccase that functions in cuticle pigmentation and tanning by oxidizing dopamine and dopamine derivatives. AgMCO3 is a mosquito-specific gene that is expressed predominantly in adult midguts and Malpighian tubules. To determine its enzymatic function, we purified recombinant AgMCO3 and analyzed its activity. AgMCO3 oxidized hydroquinone (a p-diphenol), the five o-diphenols tested, 2,2?-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), and p-phenylenediamine, but not ferrous iron. The catalytic efficiencies of AgMCO3 were similar to those of cuticular laccases (MCO2 orthologs), except that AgMCO3 oxidized all of the phenolic substrates with similar efficiencies whereas the MCO2 isoforms were less efficient at oxidizing catechol or dopa. These results demonstrate that AgMCO3 can be classified as a laccase and suggest that AgMCO3 has a somewhat broader substrate specificity than MCO2 orthologs. In addition, we observed AgMCO3 immunoreactivity in the peritrophic matrix, which functions as a selective barrier between the blood meal and midgut epithelial cells, protecting the midgut from mechanical damage, pathogens, and toxic molecules. We propose that AgMCO3 may oxidize toxic molecules in the blood meal leading to detoxification or to cross-linking of the molecules to the peritrophic matrix, thus targeting them for excretion. PMID:22479493

Lang, Minglin; Kanost, Michael R.; Gorman, Maureen J.

2012-01-01

188

Comparison of membrane-bound and soluble polyphenol oxidase in Fuji apple (Malus domestica Borkh. cv. Red Fuji).  

PubMed

This study compared membrane-bound with soluble polyphenol oxidase (mPPO and sPPO, respectively) from Fuji apple. Purified mPPO and partially purified sPPO were used. mPPO was purified by temperature-induced phase partitioning and ion exchange chromatography. The specific activity of mPPO was 34.12× higher than that of sPPO. mPPO was more stable than sPPO at pH 5.0-8.5. Although mPPO was more easily inactivated at 25-55°C, it is still more active than sPPO in this temperature range. The optimum substrate of mPPO was 4-methyl catechol, followed by catechol. l-cysteine had the highest inhibitory effects on mPPO followed by ascorbic acid and glutathione. Surprisingly, EDTA increased mPPO activity. The results revealed that purified mPPO is a dimer with a molecular weight of approximately 67kDa. PMID:25465998

Liu, Fang; Zhao, Jin-Hong; Gan, Zhi-Lin; Ni, Yuan-Ying

2015-04-15

189

Catechol-O-Methyltransferase Val158Met Polymorphism Associates with Individual Differences in Sleep  

E-print Network

baseline REM sleep latency. The genotypes, however, did not differ in performance across various executiveCatechol-O-Methyltransferase Val158Met Polymorphism Associates with Individual Differences in Sleep Physiologic Responses to Chronic Sleep Loss Namni Goel1 *, Siobhan Banks1¤ , Ling Lin2 , Emmanuel Mignot2

Bushman, Frederic

190

Inhibition of catechol 2,3-dioxygenase from Pseudomonas putida by 3-chlorocatechol.  

PubMed

Partially purified preparations of catechol 2,3-dioxygenase from toluene-grown cells of Pseudomonas putida catalyzed the stoichiometric oxidation of 3-methylcatechol to 2-hydroxy-6-oxohepta-2,4-dienoate. Other substrates oxidized by the enzyme preparation were catechol, 4-methylcatechol, and 4-fluorocatechol. The apparent Michaelis constants for 3-methylcatechol and catechol were 10.6 and 22.0 muM, respectively. Substitution at the 4-position decreases the affinity and activity of the enzyme for the substrate. Catechol 2,3-dioxygenase preparations did not oxidize 3-chlorocatechol. In addition, incubation of the enzyme with 3-chlorocatechol led to inactivation of the enzyme. Kinetic analyses revealed that both 3-chlorocatechol and 4-chlorocatechol were noncompetitive or mixed-type inhibitors of the enzyme. 3-Chlorocatechol (Ki = 0.14 muM) was a more potent inhibitor than 4-chlorocatechol (Ki = 50 muM). The effect of the ion-chelating agents Tiron and o-phenanthrolene were compared with that of 3-chlorocatechol on the inactivation of the enzyme. Each inhibitor appeared to remove iron from the enzyme, since inactive enzyme preparations could be fully reactivated by treatment with ferrous iron and a reducing agent. PMID:7259155

Klecka, G M; Gibson, D T

1981-05-01

191

Removal of arsenic, vanadium and/or nickel compounds from spent catecholated polymer  

DOEpatents

Described is a process for removing arsenic, vanadium, and/or nickel from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. For vanadium and nickel removal an amine, preferably a diamine is included. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic, vanadium, and/or nickel bound to it from contacting petroliferous liquid as described above and involves: treating the spent polymer containing any vanadium and/or nickel with an aqueous acid to achieve an acid pH; and, separating the solids from the liquid; and then treating said spent catecholated polystyrene, at a temperature in the range of about 20.degree. to 100.degree. C. with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10; and, separating the solids and liquids from each other. Preferably the regeneration treatment of arsenic containing catecholated polymer is in two steps wherein the first step is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, the steps are repeated using a bicarbonate.

Fish, Richard H. (Berkeley, CA)

1987-01-01

192

Removal of arsenic, vanadium and/or nickel compounds from spent catecholated polymer  

DOEpatents

Described is a process for removing arsenic, vanadium, and/or nickel from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. For vanadium and nickel removal an amine, preferably a diamine is included. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic, vanadium, and/or nickel bound to it from contacting petroliferous liquid as described above and involves: treating the spent polymer containing any vanadium and/or nickel with an aqueous acid to achieve an acid pH; and, separating the solids from the liquid; and then treating said spent catecholated polystyrene, at a temperature in the range of about 20 to 100 C with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10; and, separating the solids and liquids from each other. Preferably the regeneration treatment of arsenic containing catecholated polymer is in two steps wherein the first step is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, the steps are repeated using a bicarbonate.

Fish, R.H.

1987-04-21

193

Association of Catechol-O-Methyltransferase (COMT) Polymorphism and Academic Achievement in a Chinese Cohort  

ERIC Educational Resources Information Center

Catechol-O-methyltransferase (COMT) is a methylation enzyme that catalyzes the degradation pathway and inactivation of dopamine. It is accepted widely as being involved in the modulation of dopaminergic physiology and prefrontal cortex (PFC) function. The COMT Val158Met polymorphism is associated with variation in COMT activity. COMT 158Met allele…

Yeh, Ting-Kuang; Chang, Chun-Yen; Hu, Chung-Yi; Yeh, Ting-Chi; Lin, Ming-Yeh

2009-01-01

194

The Intracellular Pathogen Rhodococcus equi Produces a Catecholate Siderophore Required for Saprophytic Growth  

Microsoft Academic Search

Little is known about the iron acquisition systems of the soilborne facultative intracellular pathogen Rhodococcus equi. We previously reported that expression of iupABC, encoding a putative siderophore ABC transporter system, is iron regulated and required for growth at low iron concentrations. Here we show that disruption of iupA leads to the concomitant accumulation of catecholates and a chromophore with absorption

Raul Miranda-CasoLuengo; John F. Prescott; J. A. Vazquez-Boland; W. G. Meijer

2008-01-01

195

Urinary excretion of phenol, catechol, hydroquinone, and muconic acid by workers  

E-print Network

if this occurs in humans, benzene metabolites in urine samples collected as part of a cross sectional study;55:705­711) Keywords: benzene; phenol; catechol; hydroquinone; muconic acid; biomonitoring Occupational exposure the ubiquity of benzene in the general environment.1 Because human data are sparse on risk of leukaemia due

California at Berkeley, University of

196

Direct vs. indirect mechanisms for electron injection in DSSC: Catechol and alizarin  

Microsoft Academic Search

Catechol and alizarin have become model sensitizers for Dye Sensitized Solar Cells in recent years due to their capability to rapidly inject photoexcited electrons into the semiconductor conduction band. Because of their different geometries and electronic structures both dyes present important differences as sensitizers and operate through different mechanisms for electronic injection into semiconductor conduction band.DSSCs employing alizarin are classified

R. Sánchez-de-Armas; M. A. San-Miguel; J. Oviedo; J. Fdez. Sanz

2011-01-01

197

Inhibition of Diamine Oxidase Activity by Metronidazole  

Microsoft Academic Search

Metronidazole was found to be a non-competitive inhibitor of man, rabbit and rat intestinal diamine oxidases with an inhibition constant value of ? 10?4 M. The purified bovine serum amine oxidase was not inhibited, whereas the purified swine kidney enzyme gave similar results. These findings suggest that metronidazole and similar compounds, used as antibacterial and antiprotozoal drugs, should be given

O. Befani; T. S. Shiozaki; P. Turini; P. Gerosa; B. Mondovi

1995-01-01

198

Highly efficient purification of porcine diamine oxidase  

Microsoft Academic Search

Diamine oxidase (DAO) is a member of the class of copper-containing amine oxidases and catalyzes the oxidative deamination of histamine and other biogenic amines. The enzyme from porcine kidney was purified by consecutive chromatography on concanavalin A Sepharose, heparin Sepharose and Mono Q. Besides being simpler and faster than previous methods, this new purification scheme results in a homogenous product

Doris Wilflingseder; Hubert G Schwelberger

2000-01-01

199

Growth of Actinobacillus pleuropneumoniae is promoted by exogenous hydroxamate and catechol siderophores.  

PubMed Central

Siderophores bind ferric ions and are involved in receptor-specific iron transport into bacteria. Six types of siderophores were tested against strains representing the 12 different serotypes of Actinobacillus pleuropneumoniae. Ferrichrome and bis-catechol-based siderophores showed strong growth-promoting activities for A. pleuropneumoniae in a disk diffusion assay. Most strains of A. pleuropneumoniae tested were able to use ferrichrome (21 of 22 or 95%), ferrichrome A (20 of 22 or 90%), and lysine-based bis-catechol (20 of 22 or 90%), while growth of 36% (8 of 22) was promoted by a synthetic hydroxamate, N5-acetyl-N5-hydroxy-L-ornithine tripeptide. A. pleuropneumoniae serotype 1 (strain FMV 87-682) and serotype 5 (strain 2245) exhibited a distinct yellow halo around colonies on Chrome Azurol S agar plates, suggesting that both strains can produce an iron chelator (siderophore) in response to iron stress. The siderophore was found to be neither a phenolate nor a hydroxamate by the chemical tests of Arnow and Csaky, respectively. This is the first report demonstrating the production of an iron chelator and the use of exogenous siderophores by A. pleuropneumoniae. A spermidine-based bis-catechol siderophore conjugated to a carbacephalosporin was shown to inhibit growth of A. pleuropneumoniae. A siderophore-antibiotic-resistant strain was isolated and shown to have lost the ability to use ferrichrome, synthetic hydroxamate, or catechol-based siderophores when grown under conditions of iron restriction. This observation indicated that a common iron uptake pathway, or a common intermediate, for hydroxamate- and catechol-based siderophores may exist in A. pleuropneumoniae. PMID:8975614

Diarra, M S; Dolence, J A; Dolence, E K; Darwish, I; Miller, M J; Malouin, F; Jacques, M

1996-01-01

200

Catechol formation: a novel pathway in the metabolism of sterigmatocystin and 11-methoxysterigmatocystin.  

PubMed

The mycotoxin sterigmatocystin (STC) has an aflatoxin-like structure including a furofuran ring system. Like aflatoxin B1, STC is a liver carcinogen and forms DNA adducts after metabolic activation to an epoxide at the furofuran ring. In incubations of STC with human P450 isoforms, one monooxygenated and one dioxygenated STC metabolite were recently reported, and a GSH adduct was formed when GSH was added to the incubations. However, the chemical structures of these metabolites were not unambiguously elucidated. We now report that hepatic microsomes from humans and rats predominantly form the catechol 9-hydroxy-STC via hydroxylation of the aromatic ring. No STC-1,2-oxide and only small amounts of STC-1,2-dihydrodiol were detected in microsomal incubations, suggesting that epoxidation is a minor pathway compared to catechol formation. Catechol formation was also much more pronounced than furofuran epoxidation in the microsomal metabolism of 11-methoxysterigmatocystin (MSTC). In support of the preference of catechol formation, only trace amounts of the thiol adduct of the 1,2-oxides but large amounts of the thiol adducts of the 9-hydroxy-8,9-quinones were obtained when N-acetyl-l-cysteine was added to the microsomal incubations of STC and MSTC. In addition to hydroxylation at C-9, smaller amounts of 12c-hydroxylated, 9,12c-dihydroxylated, and 9,11-dihydroxylated metabolites were formed. Our study suggests that hydroxylation of the aromatic ring, yielding a catechol, represents a major and novel pathway in the oxidative metabolism of STC and MSTC, which may contribute to the toxic and genotoxic effects of these mycotoxins. PMID:25380456

Pfeiffer, Erika; Fleck, Stefanie C; Metzler, Manfred

2014-12-15

201

Catechol oxidation by ozone and hydroxyl radicals at the air-water interface.  

PubMed

Anthropogenic emissions of aromatic hydrocarbons promptly react with hydroxyl radicals undergoing oxidation to form phenols and polyphenols (e.g., catechol) typically identified in the complex mixture of humic-like substances (HULIS). Because further processing of polyphenols in secondary organic aerosols (SOA) can continue mediated by a mechanism of ozonolysis at interfaces, a better understanding about how these reactions proceed at the air-water interface is needed. This work shows how catechol, a molecular probe of the oxygenated aromatic hydrocarbons present in SOA, can contribute interfacial reactive species that enhance the production of HULIS under atmospheric conditions. Reactive semiquinone radicals are quickly produced upon the encounter of 40 ppbv-6.0 ppmv O3(g) with microdroplets containing [catechol] = 1-150 ?M. While the previous pathway results in the instantaneous formation of mono- and polyhydroxylated aromatic rings (PHA) and chromophoric mono- and polyhydroxylated quinones (PHQ), a different channel produces oxo- and dicarboxylic acids of low molecular weight (LMW). The cleavage of catechol occurs at the 1,2 carbon-carbon bond at the air-water interface through the formation of (1) an ozonide intermediate, (2) a hydroperoxide, and (3) cis,cis-muconic acid. However, variable [catechol] and [O3(g)] can affect the ratio of the primary products (cis,cis-muconic acid and trihydroxybenzenes) and higher order products observed (PHA, PHQ, and LMW oxo- and dicarboxylic acids). Secondary processing is confirmed by mass spectrometry, showing the production of crotonic, maleinaldehydic, maleic, glyoxylic, and oxalic acids. The proposed pathway can contribute precursors to aqueous SOA (AqSOA) formation, converting aromatic hydrocarbons into polyfunctional species widely found in tropospheric aerosols with light-absorbing brown carbon. PMID:25423038

Pillar, Elizabeth A; Camm, Robert C; Guzman, Marcelo I

2014-12-16

202

Regulation of innate immunity by NADPH oxidase  

PubMed Central

NADPH oxidase is a critical regulator of both antimicrobial host defense and inflammation. Activated in nature by microbes and microbial-derived products, the phagocyte NADPH oxidase is rapidly assembled, and generates reactive oxidant intermediates (ROIs) in response to infectious threat. Chronic granulomatous disease (CGD) is an inherited disorder of the NADPH oxidase characterized by recurrent and severe bacterial and fungal infections, and pathology related to excessive inflammation. Studies in CGD patients and CGD mouse models indicate that NADPH oxidase plays a key role in modulating inflammation and injury that is distinct from its antimicrobial function. The mechanisms by which NADPH oxidase mediates killing of pathogens and regulation of inflammation has broad relevance to our understanding of normal physiological immune responses and pathological states, such as acute lung injury and bacterial or fungal infections. PMID:22583699

Segal, Brahm H.; Grimm, Melissa J.; Khan, A. Nazmul H.; Han, Wei; Blackwell, Timothy S.

2012-01-01

203

EVALUATING RICE WILDE RELATIVES (ORYZA SPP.) FOR DISEASE RESISTANCE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rice wild relatives (Oryza spp.) are an important source of novel pest resistance genes, as well as tolerance to abiotic stresses and yield enhancing traits. Rice sheath blight caused by Rhizoctonia solani Kühn and leaf blast, Magnaporthe grisea (T.T. Herbert) Yaegashi & Udagawa, are major fungal d...

204

Immunological comparison of sulfite oxidase  

SciTech Connect

Polyclonal antibodies (rabbit), elicited against FPLC-purified chicken and rat liver sulfite oxidase (SO), have been examined for inhibition and binding to purified chicken (C), rat (R), bovine (B), alligator (A) and shark (S) liver enzymes. Anti-CSO IgG cross-reacted with all five enzymes, with varying affinities, in the order CSO=ASO{gt}RSO{gt}BSO{gt}SSO. Anti-ROS IgG also cross-reacted with all five enzymes in the order RSO{gt}CSO=ASO{gt}BSO{gt}SSO. Anti-CSO IgG inhibited sulfite:cyt. c reductase (S:CR), sulfite:ferricyanide reductase (S:FR) and sulfite:dichlorophenolindophenol reductase (S:DR) activities of CSO to different extents (S:CR{gt}S:FR=S:DR). Similar differential inhibition was found for anti-ROS IgG and RSO S:CR, S:FR and S:DR activities. Anti-CSO IgG inhibited S:CR activities in the order CSO=ASO{much gt}SSO{gt}BSO. RSO was uninhibited. For anti-RSO IgG the inhibition order was RSO{gt}SSO{gt}BSO{gt}ASO. CSO was uninhibited. Anti-CSO and RSO IgGs partially inhibited Chlorella nitrate reductase (NR). Minor cross-reactivity was found for xanthine oxidase. Common antigenic determinants for all five SO's and NR are indicated.

Pollock, V.; Barber, M.J. (Univ. South Florida College, Tampa (United States))

1991-03-11

205

Could abiotic stress tolerance in wild relatives of rice be used to improve Oryza sativa?  

PubMed

Oryza sativa and Oryza glaberrima have been selected to acquire and partition resources efficiently as part of the process of domestication. However, genetic diversity in cultivated rice is limited compared to wild Oryza species, in spite of 120,000 genotypes being held in gene banks. By contrast, there is untapped diversity in the more than 20 wild species of Oryza, some having been collected from just a few coastal locations (e.g. Oryza schlechteri), while others are widely distributed (e.g. Oryza nivara and Oryza rufipogon). The extent of DNA sequence diversity and phenotypic variation is still being established in wild Oryza, with genetic barriers suggesting a vast range of morphologies and function even within species, such as has been demonstrated for Oryza meridionalis. With increasing climate variability and attempts to make more marginal land arable, abiotic and biotic stresses will be managed over the coming decades by tapping into the genetic diversity of wild relatives of O. sativa. To help create a more targeted approach to sourcing wild rice germplasm for abiotic stress tolerance, we have created a climate distribution map by plotting the natural occurrence of all Oryza species against corresponding temperature and moisture data. We then discuss interspecific variation in phenotype and its significance for rice, followed by a discussion of ways to integrate germplasm from wild relatives into domesticated rice. PMID:24388514

Atwell, Brian J; Wang, Han; Scafaro, Andrew P

2014-02-01

206

Polyamine Oxidase5 Regulates Arabidopsis Growth through Thermospermine Oxidase Activity.  

PubMed

The major plant polyamines (PAs) are the tetraamines spermine (Spm) and thermospermine (T-Spm), the triamine spermidine, and the diamine putrescine. PA homeostasis is governed by the balance between biosynthesis and catabolism; the latter is catalyzed by polyamine oxidase (PAO). Arabidopsis (Arabidopsis thaliana) has five PAO genes, AtPAO1 to AtPAO5, and all encoded proteins have been biochemically characterized. All AtPAO enzymes function in the back-conversion of tetraamine to triamine and/or triamine to diamine, albeit with different PA specificities. Here, we demonstrate that AtPAO5 loss-of-function mutants (pao5) contain 2-fold higher T-Spm levels and exhibit delayed transition from vegetative to reproductive growth compared with that of wild-type plants. Although the wild type and pao5 are indistinguishable at the early seedling stage, externally supplied low-dose T-Spm, but not other PAs, inhibits aerial growth of pao5 mutants in a dose-dependent manner. Introduction of wild-type AtPAO5 into pao5 mutants rescues growth and reduces the T-Spm content, demonstrating that AtPAO5 is a T-Spm oxidase. Recombinant AtPAO5 catalyzes the conversion of T-Spm and Spm to triamine spermidine in vitro. AtPAO5 specificity for T-Spm in planta may be explained by coexpression with T-Spm synthase but not with Spm synthase. The pao5 mutant lacking T-Spm oxidation and the acl5 mutant lacking T-Spm synthesis both exhibit growth defects. This study indicates a crucial role for T-Spm in plant growth and development. PMID:24906355

Kim, Dong Wook; Watanabe, Kanako; Murayama, Chihiro; Izawa, Sho; Niitsu, Masaru; Michael, Anthony J; Berberich, Thomas; Kusano, Tomonobu

2014-06-01

207

Synthesis and structure/antioxidant activity relationship of novel catecholic antioxidant structural analogues to hydroxytyrosol and its lipophilic esters.  

PubMed

A large panel of novel catecholic antioxidants and their fatty acid or methyl carbonate esters has been synthesized in satisfactory to good yields through a 2-iodoxybenzoic acid (IBX)-mediated aromatic hydroxylation as the key step. The new catechols are structural analogues of naturally occurring hydroxytyrosol (3,4-DHE). To evaluate structure/activity relationships, the antioxidant properties of all catecholic compounds were evaluated in vitro by ABTS assay and on whole cells by DCF fluorometric assay and compared with that of the corresponding already known hydroxytyrosyl derivatives. Results outline that all of the new catechols show antioxidant capacity in vitro higher than that of the corresponding hydroxytyrosyl derivatives. Less evident positive effects have been detected in whole cells experiments. Cytotoxicity experiments, using MTT assay, on a representative set of compounds evidenced no influence in cell survival. PMID:22780104

Bernini, Roberta; Crisante, Fernanda; Barontini, Maurizio; Tofani, Daniela; Balducci, Valentina; Gambacorta, Augusto

2012-08-01

208

Structure and inhibition of human diamine oxidase.  

PubMed

Humans have three functioning genes that encode copper-containing amine oxidases. The product of the AOC1 gene is a so-called diamine oxidase (hDAO), named for its substrate preference for diamines, particularly histamine. hDAO has been cloned and expressed in insect cells and the structure of the native enzyme determined by X-ray crystallography to a resolution of 1.8 A. The homodimeric structure has the archetypal amine oxidase fold. Two active sites, one in each subunit, are characterized by the presence of a copper ion and a topaquinone residue formed by the post-translational modification of a tyrosine. Although hDAO shares 37.9% sequence identity with another human copper amine oxidase, semicarbazide sensitive amine oxidase or vascular adhesion protein-1, its substrate binding pocket and entry channel are distinctly different in accord with the different substrate specificities. The structures of two inhibitor complexes of hDAO, berenil and pentamidine, have been refined to resolutions of 2.1 and 2.2 A, respectively. They bind noncovalently in the active-site channel. The inhibitor binding suggests that an aspartic acid residue, conserved in all diamine oxidases but absent from other amine oxidases, is responsible for the diamine specificity by interacting with the second amino group of preferred diamine substrates. PMID:19764817

McGrath, Aaron P; Hilmer, Kimberly M; Collyer, Charles A; Shepard, Eric M; Elmore, Bradley O; Brown, Doreen E; Dooley, David M; Guss, J Mitchell

2009-10-20

209

Genipin-crosslinked catechol-chitosan mucoadhesive hydrogels for buccal drug delivery.  

PubMed

Drug administration via buccal mucosa is an attractive drug delivery strategy due to good patient compliance, prolonged localized drug effect, and avoidance of gastrointestinal drug metabolism and first-pass elimination. Buccal drug delivery systems need to maintain an intimate contact with the mucosa lining in the wet conditions of the oral cavity for long enough to allow drug release and absorption. For decades, mucoadhesive polymers such as chitosan (CS) and its derivatives have been explored to achieve this. In this study, inspired by the excellent wet adhesion of marine mussel adhesive protein, we developed a buccal drug delivery system using a novel catechol-functionalized CS (Cat-CS) hydrogel. We covalently bonded catechol functional groups to the backbone of CS, and crosslinked the polymer with a non-toxic crosslinker genipin (GP). We achieved two degrees of catechol conjugation (9% and 19%), forming Cat9-CS/GP and Cat19-CS/GP hydrogels, respectively. We confirmed covalent bond formation during the catechol functionalization and GP crosslinking during the gel formation. The gelation time and the mechanical properties of Cat-CS hydrogels are similar to those of CS only hydrogels. Catechol groups significantly enhanced mucoadhesion in vitro (7 out of the 10 Cat19-CS hydrogels were still in contact with porcine mucosal membrane after 6 h, whereas all of the CS hydrogels lost contact after 1.5 h). The new hydrogel systems sustained the release of lidocaine for about 3 h. In-vivo, we compared buccal patches made of Cat19-CS/GP and CS/GP adhered to rabbit buccal mucosa. We were able to detect lidocaine in the rabbit's serum at concentration about 1 ng/ml only from the Cat19-CS patch, most likely due to the intimate contact provided by mucoadhesive Cat19-CS/GP systems. No inflammation was observed on the buccal tissue in contact with any of the patches tested. These results show that the proposed catechol-modified CS hydrogel is a promising mucoadhesive and biocompatible hydrogel system for buccal drug delivery. PMID:25453967

Xu, Jinke; Strandman, Satu; Zhu, Julian X X; Barralet, Jake; Cerruti, Marta

2014-10-26

210

Structural Insights into Sulfite Oxidase Deficiency  

SciTech Connect

Sulfite oxidase deficiency is a lethal genetic disease that results from defects either in the genes encoding proteins involved in molybdenum cofactor biosynthesis or in the sulfite oxidase gene itself. Several point mutations in the sulfite oxidase gene have been identified from patients suffering from this disease worldwide. Although detailed biochemical analyses have been carried out on these mutations, no structural data could be obtained because of problems in crystallizing recombinant human and rat sulfite oxidases and the failure to clone the chicken sulfite oxidase gene. We synthesized the gene for chicken sulfite oxidase de novo, working backward from the amino acid sequence of the native chicken liver enzyme by PCR amplification of a series of 72 overlapping primers. The recombinant protein displayed the characteristic absorption spectrum of sulfite oxidase and exhibited steady state and rapid kinetic parameters comparable with those of the tissue-derived enzyme. We solved the crystal structures of the wild type and the sulfite oxidase deficiency-causing R138Q (R160Q in humans) variant of recombinant chicken sulfite oxidase in the resting and sulfate-bound forms. Significant alterations in the substrate-binding pocket were detected in the structure of the mutant, and a comparison between the wild type and mutant protein revealed that the active site residue Arg-450 adopts different conformations in the presence and absence of bound sulfate. The size of the binding pocket is thereby considerably reduced, and its position relative to the cofactor is shifted, causing an increase in the distance of the sulfur atom of the bound sulfate to the molybdenum.

Karakas,E.; Wilson, H.; Graf, T.; Xiang, S.; Jaramillo-Busquets, S.; Rajagopalan, K.; Kisker, C.

2005-01-01

211

Monoamine oxidase inhibitors and neuroprotection: a review.  

PubMed

Monoamine oxidase inhibitors have been available for more than 50 years, initially developed as antidepressants but currently used in a variety of psychiatric and neurological conditions. There has been a recent surge of interest in monoamine oxidase inhibitors because of their reported neuroprotective and/or neurorescue properties. Interestingly, it seems that often these properties are independent of their ability to inhibit monoamine oxidase. This review article presents an overview of the neuroprotective/neurorescue properties of these multifaceted drugs and focuses on phenelzine, (-)-deprenyl, rasagiline, ladostigil, tranylcypromine, moclobemide, and clorgyline and their possible neuroprotective mechanisms. PMID:22960850

Al-Nuaimi, Saleem K; Mackenzie, Erin M; Baker, Glen B

2012-11-01

212

Correlation Between Monoamine Oxidase Inhibitors and Anticonvulsants  

PubMed Central

Monoamine oxidase inhibitory and anticonvulsant properties of 2-substituted styryl-6-bromo-3-(4-ethylbenzoate/4 benzhydrazide)-4-quinazoles are studied. All styryl quinazolone esters except compound number 9 exhibited monoamine oxidase inhibitory properties during oxidative deamination of kynuramine. Corresponding hydrazides were found to have relatively higher activity. All these quinazolones were able to protect against pentylenetetrazol induced seizures. These observations in general do not prove that monoamine oxidase inhibitory properties represent the biochemical basis for the anticonvulsant activity of these compounds. PMID:7420438

Dwivedi, Chandradhar; Misra, Radhey S.; Chaudhari, Anshumali; Parmar, Surendra S.

1980-01-01

213

Inhibition of diamine oxidase activity by metronidazole.  

PubMed

Metronidazole was found to be a non-competitive inhibitor of man, rabbit and rat intestinal diamine oxidases with an inhibition constant value of approximately 10(-4) M. The purified bovine serum amine oxidase was not inhibited, whereas the purified swine kidney enzyme gave similar results. These findings suggest that metronidazole and similar compounds, used as antibacterial and antiprotozoal drugs, should be given under careful control, especially when administered for long times, because a decrease of intestinal diamine oxidase activity was proven to be a risk factor for several pathologies of this organ. PMID:7626074

Befani, O; Shiozaki, T S; Turini, P; Gerosa, P; Mondovi, B

1995-07-17

214

Factors Affecting Reaction Kinetics of Glucose Oxidase  

NASA Astrophysics Data System (ADS)

Basic principles of enzyme kinetics are demonstrated using the enzyme glucose oxidase. The glucose oxidase enzymatic reaction is coupled to horseradish peroxidase, which in turn catalyzes the oxidation of a dye to a bright blue-green color. The appearance of the blue-green dye is used to monitor the course of the reaction and is quite visible in a classroom setting. A series of reactions are arranged that vary the enzyme concentration, substrate concentration, temperature, and the substrate used in the reaction. By monitoring the rate of the color change in each beaker, the reaction kinetics of glucose oxidase in each series is observed.

Johnson, Kristin A.

2002-01-01

215

Effects of biochar and the geophagous earthworm Metaphire guillelmi on fate of (14)C-catechol in an agricultural soil.  

PubMed

Both biochar and earthworms can exert influence on behaviors of soil-borne monomeric phenols in soil; however, little was known about the combined effects of biochar and earthworm activities on fate of these chemicals in soil. Using (14)C-catechol as a representative, the mineralization, transformation and residue distribution of phenolic humus monomer in soil amended with different amounts of biochar (0%, 0.05%, 0.5%, and 5%) without/with the geophagous earthworm Metaphire guillelmi were investigated. The results showed biochar at amendment rate <0.5% did not affect (14)C-catechol mineralization, whereas 5% biochar amendment significantly inhibited the mineralization. Earthworms did not affect the mineralization of (14)C-catechol in soil amended with <0.5% biochar, but significantly enhanced the mineralization in 5% biochar amended soil when they were present in soil for 9 d. When earthworms were removed from the soil, the mineralization of (14)C-catechol was significantly lower than that of in earthworm-free soil indicating that (14)C-catecholic residues were stabilized during their passage through earthworm gut. The assimilation of (14)C by earthworms was low (1.2%), and was significantly enhanced by biochar amendment, which was attributed to the release of biochar-associated (14)C-catecholic residues during gut passage of earthworm. PMID:24875877

Shan, Jun; Wang, Yongfeng; Gu, Jianqiang; Zhou, Wenqiang; Ji, Rong; Yan, Xiaoyuan

2014-07-01

216

Lab-on-valve (LOV) system coupled to irreversible biamperometric detection for the on-line monitoring of catechol.  

PubMed

The analytical performance of lab-on-valve (LOV) system using irreversible biamperometry for the determination of catechol was evaluated. By integrating miniaturized electrochemical flow cell (EFC) designed and processed which is furnished with two identical polarized platinum electrodes, into the LOV unit, the lab-on-valve system combines sampling with analysis, realizing automated on-line analysis for catechol in a closed system. The biamperometric detection system was established to record the relationship between oxidation current and time by coupling the irreversible oxidation of catechol at one pretreated platinum electrode with the irreversible reduction of platinum oxide at the other pretreated platinum electrode. Factors influencing the analytical performance were optimized, including the potential difference (DeltaE), buffer solution and pH, and flow variables in the LOV. A linear calibration curve was obtained within the range of 1.0 x 10(-6)-5.0 x 10(-4) mol L(-1) of catechol with the detection limit (3 sigma) of 5.09 x 10(-7)mol L(-1). The relative standard deviation (R.S.D.) was 2.39% for 11 successive determinations of 1 x 10(-5)mol L(-1) catechol and the sample throughput was 35h(-1). Moreover, this proposed method was applied to the analysis of catechol in beer sample, which was testified by high-performance liquid chromatography (HPLC). PMID:20801363

Wang, Yang; Yao, Guojun; Zhu, Peihua; Hu, Xiaoya; Xu, Qin; Yang, Chun

2010-09-15

217

Inhibition of diamine oxidases and polyamine oxidases by diamine-based compounds  

Microsoft Academic Search

Summary  This review reports on inhibitors of copper-containing amine oxidases and flavoprotein polyamine oxidases, which are structurally\\u000a based on diamines. In the introduction, basic characteristics and classification of amine oxidases are described together\\u000a with the significance of their synthetic inhibitors. The following text is divided into several chapters, which deal with\\u000a diaminoketones, aza-diamines, unsaturated diamine analogs and diamines with heterocyclic substituents.

M. Šebela; M. Tylichová; P. Pe?

2007-01-01

218

Medicinal chemistry of catechol O-methyltransferase (COMT) inhibitors and their therapeutic utility.  

PubMed

Catechol O-methyltransferase (COMT) is the enzyme responsible for the O-methylation of endogenous neurotransmitters and of xenobiotic substances and hormones incorporating catecholic structures. COMT is a druggable biological target for the treatment of various central and peripheral nervous system disorders, including Parkinson's disease, depression, schizophrenia, and other dopamine deficiency-related diseases. The purpose of this perspective is fourfold: (i) to summarize the physiological role of COMT inhibitors in central and peripheral nervous system disorders; (ii) to provide the history and perspective of the medicinal chemistry behind the discovery and development of COMT inhibitors; (iii) to discuss how the physicochemical properties of recognized COMT inhibitors are understood to exert influence over their pharmacological properties; and (iv) to evaluate the clinical benefits of the most relevant COMT inhibitors. PMID:25080080

Kiss, László E; Soares-da-Silva, Patrício

2014-11-13

219

Retention of ionic and non-ionic catechols in capillary zone electrophoresis with micellar solutions.  

PubMed

The use of micellar solutions in capillary zone electrophoresis has been primarily relegated to separations of non-ionic solutes, while its applicability to cationic species has been unexplored. We have found that the use of sodium dodecyl sulfate micelles in phosphate buffer allows for tremendous gains in selectivity for several cationic and non-ionic catechols over what can be obtained with normal capillary zone electrophoresis. Complexation of catechols with boric acid alters the net charge on the solutes and changes the partitioning behavior to produce adequate selectivity with improved analysis times. Although the mechanisms of solute interaction with the micellar phase for the cationic species are not decisively known, evidence is presented supporting the existence of ion-pairing equilibria simultaneously accompanied by micellar solubilization. PMID:3410921

Wallingford, R A; Ewing, A G

1988-06-10

220

2-(Phenylazo)pyridineplatinum(II) Catecholates Showing Photocytotoxicity, Nuclear Uptake, and Glutathione-Triggered Ligand Release.  

PubMed

Platinum(II) complexes [Pt(pap)(an-cat)] (1) and [Pt(pap)(py-cat)] (2) with 2-(phenylazo)pyridine (pap), 4-[2-[(anthracen-9-ylmethylene)amino]ethyl]benzene-1,2-diol (H2an-cat), and 4-[2-[(pyren-1-ylmethylene)amino]ethyl]benzene-1,2-diol (H2py-cat) were prepared, and their photoinduced cytotoxicity was studied. The complexes were found to release catecholate ligand in the presence of excess glutathione (GSH), resulting in cellular toxicity in the cancer cells. The catecholate complex [Pt(pap)(cat)] (3) was prepared and used as a control. Complex 3, which is structurally characterized by X-ray crystallography, has platinum(II) in a distorted square-planar geometry. The complexes are redox-active, showing responses near 0.6 and 1.0 V versus SCE in N,N-dimethylformamide/0.1 M tetrabutylammonium perchlorate corresponding to a two-step catechol oxidation process and at -0.3 and -1.3 V for reduction of the pap ligand. Complex 1 showed remarkable light-induced cytotoxicity in HaCaT (human skin keratinocytes) and MCF-7 (human breast cancer) cells, giving IC50 value of ?5 ?M in visible light of 400-700 nm and >40 ?M in the dark. The 2',7'-dichlorofluorescein diacetate (DCFDA) assay showed the generation of reactive oxygen species (ROS), which seems to trigger apoptosis, as is evident from the annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) assay. The fluorescence microscopic images showed significant nuclear localization of the complexes and free ligands. A mechanistic study revealed possible reduction of the coordinated azo bond of pap by cellular GSH, releasing the catecholate ligand and resulting in remarkable photochemotherapeutic action of the complexes. PMID:25496358

Mitra, Koushambi; Patil, Shilpa; Kondaiah, Paturu; Chakravarty, Akhil R

2015-01-01

221

Catechol-O-methyltransferase gene haplotypes in Mexican and Spanish patients with fibromyalgia  

Microsoft Academic Search

Autonomic dysfunction is frequent in patients with fibromyalgia (FM). Heart rate variability analyses have demonstrated signs of ongoing sympathetic hyperactivity. Catecholamines are sympathetic neurotransmitters. Catechol-O-methyltransferase (COMT), an enzyme, is the major catecholamine-clearing pathway. There are several single-nucleotide polymorphisms (SNPs) in the COMT gene associated with the different catecholamine-clearing abilities of the COMT enzyme. These SNPs are in linkage disequilibrium and

Gilberto Vargas-Alarcón; José-Manuel Fragoso; David Cruz-Robles; Angélica Vargas; Alfonso Vargas; José-Ignacio Lao-Villadóniga; Ferrán García-Fructuoso; Manuel Ramos-Kuri; Fernando Hernández; Rashidi Springall; Rafael Bojalil; Maite Vallejo; Manuel Martínez-Lavín

2007-01-01

222

Benzothiazole Degradation by Rhodococcus pyridinovorans Strain PA: Evidence of a Catechol 1,2Dioxygenase Activity  

Microsoft Academic Search

precise structure of another intermediate was determined by in situ two-dimensional 1 H- 13 C NMR and HPLC-electrospray ionization mass spectrometry; this intermediate was found to be a ring-opening product (a diacid structure). Detection of this metabolite, together with the results obtained by 1 H and 19 F NMR when cells were incubated with 3-fluorocatechol, demonstrated that a catechol 1,2-dioxygenase

Nicolas Haroune; Bruno Combourieu; Pascale Besse; Martine Sancelme; Thorsten Reemtsma; Achim Kloepfer; Amer Diab; Jeremy S. Knapp; Simon Baumberg; Anne-Marie Delort

2002-01-01

223

Association between the Catechol O-Methyltransferase Val108\\/158Met Polymorphism and Alexithymia  

Microsoft Academic Search

It has been suggested that the characteristics of alexithymia result from deficits in frontal lobe functioning, and the prefrontal cortex is particularly dependent on the catechol O-methyltransferase (COMT) pathway. We investigated the relationship between COMT Val108\\/158Met, serotonin transporter coding sequence (5-HT transporter gene-linked polymorphic region; 5-HTTLPR) polymorphisms, and alexithymia.The study sample comprised 109 students at the Korea University. All participants

Byung-Joo Ham; Min-Soo Lee; Young-Mee Lee; Meyoung-Kon Kim; Myoung-Jin Choi; Kang-Seob Oh; Han Yong Jung; In Kyoon Lyoo; Ihn-Geun Choi

2005-01-01

224

Antibacterial Activity of BMS-180680, a New Catechol-Containing Monobactam  

Microsoft Academic Search

The in vitro activities of a new catechol-containing monobactam, BMS-180680 (SQ 84,100), were compared to those of aztreonam, ceftazidime, imipenem, piperacillin-tazobactam, ciprofloxacin, amikacin, and tri- methoprim-sulfamethoxazole. BMS-180680 was often the most active compound against many species of the family Enterobacteriaceae, with MICs at which 90% of the isolates were inhibited (MIC90s) of <0.5 mg\\/ml for Escherichia coli, Klebsiella spp., Citrobacter

JOAN FUNG-TOMC; KAREN BUSH; BEATRICE MINASSIAN; BENJAMIN KOLEK; ROBERT FLAMM; ELIZABETH GRADELSKI; DANIEL BONNER

1997-01-01

225

Kinetic study on the suicide inactivation of tyrosinase induced by catechol.  

PubMed

Tyrosinase has a suicide inactivation reaction when it acts on omicron-diphenols. In the present paper, this reaction has been studied using a transient phase approach. Explicit equations of product vs. time have been developed for the multisubstrate mechanism of tyrosinase, and the kinetic parameters which characterize the enzyme acting on the suicide substrate catechol have been determined. The effect of pH has also been considered. PMID:3105585

García Cánovas, F; Tudela, J; Martínez Madrid, C; Varón, R; García Carmona, F; Lozano, J A

1987-04-30

226

Catechol production by O-demethylation of 2-methoxyphenol using the obligate anaerobe, Acetobacterium woodii  

Microsoft Academic Search

Acetobacterium woodii produced catechol (up to 7.84 mM) by demethylating 2-methoxyphenol during growth in the presence or absence of fructose. The highest product concentrations were obtained when 2-methoxyphenol was the sole energy source but the highest substrate conversion (97%) was obtained in fructose-limited chemostat culture. Growing cells were the most suitable form of the biocatalyst since the catalytic activity was

M. S. Kalil; G. M. Stephens

1997-01-01

227

Contrasting effects of catecholic and O-methylated tetrahydroisoquinolines on hydroxyl radical production  

Microsoft Academic Search

Tetrahydroisoquinolines (TIQs) are intraneuronal, catecholamine-derived alkaloids that have been implicated in the etiology of Parkinson’s disease and in alcohol related disorders. The in vitro production of the cytotoxic hydroxyl radical (?OH) was recorded during the autoxidation of salsolinol (SAL) and salsolinol-1-carboxylic acid (SAL-1C), but not when these two catecholic TIQs were oxidized by tyrosinase. Significantly higher levels of the radical

A. J Nappi; E Vass; M. A Collins

1999-01-01

228

Inhibition of microbial cholesterol oxidases by dimethylmorpholines.  

PubMed

Cholesterol oxidase is a potentially important enzyme in steroid transformations, catalysing the conversion of 3-hydroxy-5-ene steroids to 3-keto-4-ene derivatives via a 3-keto-5-ene intermediate. Morpholine derivatives, especially fenpropimorph and tridemorph, were found to block selectively the isomerisation activity of cholesterol oxidases isolated from Nocardia erythropolis, Streptomyces sp., Pseudomonas testosteroni and Schizophyllum commune. These enzymes differ strongly in physical characteristics and catalytic behaviour. The effectiveness of the inhibitors varied with the cholesterol oxidase tested. Fenpropimorph was most effective with each of the 4 enzymes, 50 mg/l inhibiting about 50% of the enzyme activity. Inhibition was instantaneous and followed a reversible competitive mechanism in Streptomyces sp. and a reversible non-competitive mechanism in Nocardia erythropolis and Schizophyllum commune. An irreversible type of inhibition was observed for P. testosteroni cholesterol oxidase. PMID:2308321

Hesselink, P G; Kerkenaar, A; Witholt, B

1990-01-01

229

Benzothiazole Degradation by Rhodococcus pyridinovorans Strain PA: Evidence of a Catechol 1,2-Dioxygenase Activity  

PubMed Central

The pathway for biodegradation of benzothiazole (BT) and 2-hydroxybenzothiazole (OBT) by Rhodococcus pyridinovorans strain PA was studied in detail. The kinetics of biodegradation were monitored by in situ 1H nuclear magnetic resonance (NMR) in parallel with reversed-phase high-performance liquid chromatography (HPLC). Successive oxidations from BT to OBT and then from OBT to dihydroxybenzothiazole were observed. Further insight was obtained by using a mutant strain with impaired ability to grow on BT and OBT. The precise structure of another intermediate was determined by in situ two-dimensional 1H-13C NMR and HPLC-electrospray ionization mass spectrometry; this intermediate was found to be a ring-opening product (a diacid structure). Detection of this metabolite, together with the results obtained by 1H and 19F NMR when cells were incubated with 3-fluorocatechol, demonstrated that a catechol 1,2-dioxygenase is involved in a pathway for biodegradation of BTs in this Rhodococcus strain. Our results show that catechol 1,2-dioxygenase and catechol 2,3-dioxygenase activities may both be involved in the biodegradation of BTs depending on the culture conditions. PMID:12450835

Haroune, Nicolas; Combourieu, Bruno; Besse, Pascale; Sancelme, Martine; Reemtsma, Thorsten; Kloepfer, Achim; Diab, Amer; Knapp, Jeremy S.; Baumberg, Simon; Delort, Anne-Marie

2002-01-01

230

Catechol-rhodanine derivatives: Specific and promiscuous inhibitors of Escherichia coli deoxyxylulose phosphate reductoisomerase (DXR).  

PubMed

To develop more effective inhibitors than fosmidomycin, a natural compound which inhibits the deoxyxylulose 5-phosphate reductoisomerase (DXR), the second enzyme of the MEP pathway, we designed molecules possessing on the one hand a catechol that is able to chelate the magnesium dication and on the other hand a group able to occupy the NADPH recognition site. Catechol-rhodanine derivatives (1-6) were synthesized and their potential inhibition was tested on the DXR of Escherichia coli. For the inhibitors 1 and 2, the presence of detergent in the enzymatic assays led to a dramatic decrease of the inhibition suggesting, that these compounds are rather promiscuous inhibitors. The compounds 4 and 5 kept their inhibition capacity in the presence of Triton X100 and could be considered as specific inhibitors of DXR. Compound 4 showed antimicrobial activity against Escherichia coli. The only partial protection of NADPH against the inhibition suggested that the catechol-rhodanine derivatives did not settle in the coenzyme binding site. This paper points out the necessity to include a detergent in the DXR enzymatic assays to avoid false positive when putative hydrophobic inhibitors are tested and especially when the IC50, are in the micromolar range. PMID:24890653

Zinglé, Catherine; Tritsch, Denis; Grosdemange-Billiard, Catherine; Rohmer, Michel

2014-07-15

231

Versatile tuning of supramolecular hydrogels through metal complexation of oxidation-resistant catechol-inspired ligands  

PubMed Central

The mussel byssal cuticle employs DOPA-Fe3+ complexation to provide strong, yet reversible crosslinking. Synthetic constructs employing this design motif based on catechol units are plagued by oxidation-driven degradation of the catechol units and the requirement for highly alkaline pH conditions leading to decreased performance and loss of supramolecular properties. Herein, a platform based on a 4-arm poly(ethylene glycol) hydrogel system is used to explore the utility of DOPA analogues such as the parent catechol and derivatives, 4-nitrocatechol (nCat) and 3-hydroxy-4-pyridinonone (HOPO), as structural crosslinking agents upon complexation with metal ions. HOPO moieties are found to hold particular promise, as robust gelation with Fe3+ occurs at physiological pH and is found to be largely resistant to oxidative degradation. Gelation is also shown to be triggered by other biorelevant metal ions such as Al3+, Ga3+ and Cu2+ which allows for tuning of the release and dissolution profiles with potential application as injectable delivery systems. PMID:24285981

Menyo, Matthew S.

2013-01-01

232

Magnetic Catechol-Chitosan with Bioinspired Adhesive Surface: Preparation and Immobilization of ?-Transaminase  

PubMed Central

The magnetic chitosan nanocomposites have been studied intensively and been used practically in various biomedical and biological applications including enzyme immobilization. However, the loading capacity and the remained activity of immobilized enzyme based on existing approaches are not satisfied. Simpler and more effective immobilization strategies are needed. Here we report a simple catechol modified protocol for preparing a novel catechol-chitosan (CCS) - iron oxide nanoparticles (IONPs) composites carrying adhesive moieties with strong surface affinity. The ?-transaminase (?-TA) was immobilized onto this magnetic composite via nucleophilic reactions between catechol and ?-TA. Under optimal conditions, 87.5% of the available ?-TA was immobilized on the composite, yielding an enzyme loading capacity as high as 681.7 mg/g. Furthermore, the valuation of enzyme activity showed that ?-TA immobilized on CCS-IONPs displayed enhanced pH and thermal stability compared to free enzyme. Importantly, the immobilized ?-TA retained more than 50% of its initial activity after 15 repeated reaction cycles using magnetic separation and 61.5% of its initial activity after storage at 4°C in phosphate buffered saline (PBS) for 15 days. The results suggested that such adhesive magnetic composites may provide an improved platform technology for bio-macromolecules immobilized. PMID:22815930

Ni, Kefeng; Zhou, Xu; Zhao, Li; Wang, Hualei; Ren, Yuhong; Wei, Dongzhi

2012-01-01

233

Magnetic catechol-chitosan with bioinspired adhesive surface: preparation and immobilization of ?-transaminase.  

PubMed

The magnetic chitosan nanocomposites have been studied intensively and been used practically in various biomedical and biological applications including enzyme immobilization. However, the loading capacity and the remained activity of immobilized enzyme based on existing approaches are not satisfied. Simpler and more effective immobilization strategies are needed. Here we report a simple catechol modified protocol for preparing a novel catechol-chitosan (CCS)-iron oxide nanoparticles (IONPs) composites carrying adhesive moieties with strong surface affinity. The ?-transaminase (?-TA) was immobilized onto this magnetic composite via nucleophilic reactions between catechol and ?-TA. Under optimal conditions, 87.5% of the available ?-TA was immobilized on the composite, yielding an enzyme loading capacity as high as 681.7 mg/g. Furthermore, the valuation of enzyme activity showed that ?-TA immobilized on CCS-IONPs displayed enhanced pH and thermal stability compared to free enzyme. Importantly, the immobilized ?-TA retained more than 50% of its initial activity after 15 repeated reaction cycles using magnetic separation and 61.5% of its initial activity after storage at 4°C in phosphate buffered saline (PBS) for 15 days. The results suggested that such adhesive magnetic composites may provide an improved platform technology for bio-macromolecules immobilized. PMID:22815930

Ni, Kefeng; Zhou, Xu; Zhao, Li; Wang, Hualei; Ren, Yuhong; Wei, Dongzhi

2012-01-01

234

The polyamine oxidase inactivator MDL 72527.  

PubMed

Polyamine oxidase is a FAD-dependent amine oxidase, which is constitutively expressed in nearly all tissues of the vertebrate organism. In 1985, N1,N4-bis(2,3-butadienyl)-1,4-butanediamine (MDL 72527) was designed as a selective enzyme-activated irreversible inhibitor of polyamine oxidase (EC 1.5.3.11). It inactivates, at micromolar concentration and time-dependently, the enzyme in cells, as well as in all organs of experimental animals, without inhibiting other enzymes of polyamine metabolism. MDL 72527 served during nearly two decades as a unique tool in the elucidation of the physiological roles of polyamine oxidase. The compound has anticancer and contragestational effects, and it improves the anticancer effect of the ornithine decarboxylase inactivator (D,L)-2-(difluoromethyl)ornithine (DFMO). Profound depletion of the polyamine pools of tumour cells and effects on different components of the immune defence system are responsible for the anticancer effects of MDL 72527/DFMO combinations. Recently a direct cytotoxic effect of MDL 72527 at concentrations above those required for polyamine oxidase inactivation was observed. The induction of apoptosis by MDL 72527 was ascribed to its lysosomotropic properties. Therapeutic potentials of the apoptotic effect of MDL 72527 need to be explored. Polyamine oxidase is the last enzyme of the polyamine interconversion pathway that awaits the detailed elucidation of its structure and regulation. MDL 72527 should be useful as a lead in the development of inactivators which are selective for the isoforms of polyamine oxidase. Isozyme-selective inhibitors will give more profound insights into and reveal a diversity of specific functions of polyamine oxidase. PMID:12458962

Seiler, Nikolaus; Duranton, Benoit; Raul, Francis

2002-01-01

235

Initial characerization of human spermine oxidase  

E-print Network

INITIAL CHARACTERIZATION OF HUMAN SPERMINE OXIDASE A Thesis by PAUL RAMON JUAREZ Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE December 2008 Major Subject: Biochemistry INITIAL CHARACTERIZATION OF HUMAN SPERMINE OXIDASE A Thesis by PAUL RAMON JUAREZ Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment...

Juarez, Paul Ramon

2009-05-15

236

17 beta-Estradiol metabolism by hamster hepatic microsomes. Implications for the catechol-O-methyl transferase-mediated detoxication of catechol estrogens.  

PubMed

We have shown that the metabolism of 17 beta-estradiol in hamster liver microsomes is concentration-dependent. At low (< 25 microM) concentrations of 17 beta-estriol, 16 alpha-hydroxylase activity predominated, and estriol was the major metabolite. At higher concentrations (25-75 microM), 16 alpha-hydroxylation and aromatic hydroxylation at C2 contributed equally to 17 beta-estradiol metabolism. Aromatic C4-hydroxylation was maximal at 75 microM of 17 beta-estradiol and was always less than C2-hydroxylation. Dehydrogenation of the 17 beta-hydroxyl group to the ketone (estrone) was also observed, but both estrone and 2-hydroxyestrone were minor (approximately 3%) metabolites of 17 beta-estradiol, only detectable at concentrations of 50 microM and above. Catechol-O-methyl transferase (COMT) effectively converted both 2- and 4-hydroxyl-17 beta-estradiol to their corresponding monomethoxy metabolites. Effective reducing conditions are required for COMT activity, because catechol estrogens are readily oxidized to their corresponding ortho-quinones, and ascorbic acid is routinely added to assays of COMT activity. Interestingly, although ascorbic acid (1 mM) increased the recovery of 2- and 4-hydroxy-17 beta-estradiol from microsomal incubations, it decreased the recovery of the methoxy metabolites (approximately 40%). Since the enediol function of ascorbate resembles that of a catechol group, ascorbate is a substrate for COMT and probably competes with the catechol estrogens for methylation. Because previous studies describing the ability of COMT to inhibit the covalent binding of electrophilic reactive metabolites of [4-(14)C]17 beta-estradiol to microsomal protein were performed in the presence of high (100 mM) Mg2+ concentrations, we also investigated the effects of Mg2+ on 17 beta-estradiol metabolism. Concentrations of Mg2+ > 10 mM inhibited the metabolism of 17 beta-estradiol, as evidenced by i) the increased recovery of substrate; ii) a decrease in the formation of estriol, estrone, and 2-, and 4-hydroxy-17 beta-estradiol; iii) a decrease in the recovery of water-soluble metabolites when incubations were performed in the presence of glutathione (GSH) to trap the reactive electrophilic metabolites; and iv) a decrease in the amount of reactive electrophilic metabolites bound to microsomal protein. GSH also decreased the covalent binding of electrophilic metabolites of [4-(14)C]17 beta-estradiol to microsomal protein, with the concomitant formation of water-soluble metabolites. Thus, both COMT and GSH combine to limit the formation of electrophilic metabolites from 17 beta-estradiol. The relative importance of each of these pathways to the disposition of the catechol estrogens remains to be determined. PMID:8723741

Butterworth, M; Lau, S S; Monks, T J

1996-05-01

237

The mammalian aldehyde oxidase gene family  

PubMed Central

Aldehyde oxidases (EC 1.2.3.1) are a small group of structurally conserved cytosolic proteins represented in both the animal and plant kingdoms. In vertebrates, aldehyde oxidases constitute the small sub-family of molybdo-flavoenzymes, along with the evolutionarily and structurally related protein, xanthine oxidoreductase. These enzymes require a molybdo-pterin cofactor (molybdenum cofactor, MoCo) and flavin adenine dinucleotide for their catalytic activity. Aldehyde oxidases have broad substrate specificity and catalyse the hydroxylation of N-heterocycles and the oxidation of aldehydes to the corresponding acid. In humans, a single aldehyde oxidase gene (AOX1) and two pseudogenes clustering on a short stretch of chromosome 2q are known. In other mammals, a variable number of structurally conserved aldehyde oxidase genes has been described. Four genes (Aox1, Aox3, Aox4 and Aox3l1), coding for an equivalent number of catalytically active enzymes, are present in the mouse and rat genomes. Although human AOX1 and its homologous proteins are best known as drug metabolising enzymes, the physiological substrate(s) and function(s) are as yet unknown. The present paper provides an update of the available information on the evolutionary history, tissue- and cell-specific distribution and function of mammalian aldehyde oxidases. PMID:20038499

2009-01-01

238

Inhibition of monoamine oxidase by substituted hydrazines  

PubMed Central

1. The initial rate of inhibition of monoamine oxidase by phenethylhydrazine was shown to be similar, in pH-dependence and kinetic properties, to the oxidation of that compound by monoamine oxidase. 2. The time-course of irreversible inhibition of monoamine oxidase by phenethylhydrazine lags behind that of reversible inhibition. 3. Hydralzine was shown to be a reversible competitive inhibitor of monoamine oxidase, but phenylhydrazine is an irreversible inhibitor. Inhibition by the latter compound is not affected by the absence of oxygen, and the presence of substrate exerts no protective action. 4. Hydrazine does not inhibit monoamine oxidase unless a substrate and oxygen are present. 5. Phenethylidenehydrazine was found to be a time-dependent inhibitor of monoamine oxidase and the rate of inhibition was hindered by increasing oxygen concentration. 6. A mechanism for the inhibition of the enzyme by phenethylhydrazine is proposed in which the product of oxidation of this compound is a potent reversible inhibitor and an irreversible inhibitor of the enzyme. A computer simulation of such a mechanism predicts time-courses of inhibition that are in reasonable agreement with those observed experimentally. PMID:4674124

Tipton, Keith F.

1972-01-01

239

Saccharification of Job's Tears Flour during Fermentation of Aspergillus oryzae  

Microsoft Academic Search

The effects of pH, initial substrate concentration and addition of sodium chloride on saccharification of Job's tears flour during fermen tation of Aspergillus oryzae were examined. The result of proximate analysis of Job's Tears flo ur showed that it contained 64.3% carbohydrate, 12.4% protein, 4.8% fat, 6.6% insolub le fiber, 1.7% ash and 10.2% moisture. The saccharification rate based on

Sasivimol Chuen-Im Ahmed; Wanida Chiansanoi; Sivatat Cosa

240

[Occupational extrinsic allergic alveolitis due to Aspergillus oryzae].  

PubMed

We report a case of extrinsic allergic alveolitis, provoked by Deterzyme, a product used in dermatology for the cleaning of cutaneous sores, and containing fractions of protolytic enzymes and amylases of Aspergillus oryzae. The diagnosis was based on the positive precipitins to an extract of antigen of the product as well as positive bronchial provocation tests (semi-delayed) and the disappearance of the symptomatology without any sequelae following cessation of exposure to the risk. PMID:7694333

Gueland, C; Fruit, J; Vannimenus, C; Wallaert, B; Tonnel, A B

1993-01-01

241

Purification and Some Properties of Two Polyphenol Oxidases from Bartlett Pears 1  

PubMed Central

Two polyphenol oxidases (enzymes A and B) from Bartlett pear (Pyrus communis) peelings were purified to electrophoretic homogeneity according to polyacrylamide gel by a combination of Sephadex gel filtration, diethylaminoethyl cellulose chromatography and hydroxyl apatite chromatography. While the two enzymes differ electrophoretically at pH 9.3, chromatographically on hydroxyl apatite, and in the effect of ionic strength on activity, they are similar with respect to chromatography on diethylaminoethyl cellulose, substrate specificity, pH activity relations, inhibition by p-coumaric and benzoic acids, and heat stability. The two enzymes are o-diphenol oxidases with no detectable monophenolase or laccase activities. Pyrocatechol, 4-methyl catechol, chlorogenic acid, and d-catechin are good substrates of the enzymes with Km values in the range of 2 to 20 mm. Dependences of activity on oxygen and chlorogenic acid concentrations indicate a sequential mechanism for binding of these substrates to enzyme B. Vmax and Km values for oxygen and chlorogenic acid were 103 ?moles O2 uptake per minute per milligram of enzyme, 0.11 mm and 7.2 mm, respectively, for enzyme B at pH 4.0. Both enzymes had maximum activity at pH 4.0 on chlorogenic acid. Km values for chlorogenic acid were independent of pH from 3 to 7; the Vmax values for both enzymes gave bell-shaped curves as a function of pH. p-Coumaric acid is a simple, linear noncompetitive inhibitor with respect to chlorogenic acid at pH 6.2 with Ki values of 0.38 and 0.50 mm for enzymes A and B, respectively. Benzoic acid is a linear competitive inhibitor with respect to chlorogenic acid at pH 4.0 with Ki values of 0.04 and 0.11 mm for enzymes A and B, respectively. PMID:16658592

de Jesus Rivas, Nilo; Whitaker, John R.

1973-01-01

242

Crystallization and preliminary X-ray crystallographic analysis of the XoGroEL chaperonin from Xanthomonas oryzae pv. oryzae.  

PubMed

Along with the co-chaperonin GroES, the chaperonin GroEL plays an essential role in enhancing protein folding or refolding and in protecting proteins against misfolding and aggregation in the cellular environment. The XoGroEL gene (XOO_4288) from Xanthomonas oryzae pv. oryzae was cloned and the protein was expressed, purified and crystallized. The purified XoGroEL protein was crystallized using the hanging-drop vapour-diffusion method and a crystal diffracted to a resolution of 3.4 Ĺ. The crystal belonged to the orthorhombic space group P212121 with 14 monomers in the asymmetric unit, with a corresponding VM of 2.7 Ĺ(3) Da(-1) and a solvent content of 54.5%. PMID:24817719

Tran, Huyen Thi; Pham, Tan Viet; Ngo, Ho Phuong Thuy; Hong, Myoung Ki; Kim, Jeong Gu; Lee, Sang Hee; Ahn, Yeh Jin; Kang, Lin Woo

2014-05-01

243

Changes in the Plasma Membrane Distribution of Rice Phospholipase D during Resistant Interactions with Xanthomonas oryzae pv oryzae.  

PubMed Central

Phospholipase D (PLD; EC 3.1.4.4), which hydrolyzes phospholipids to generate phosphatidic acid, was examined in rice leaves undergoing susceptible or resistant interactions with Xanthomonas oryzae pv oryzae. RNA analysis of leaves undergoing resistant interactions revealed different expression patterns for PLD over 5 days relative to control plants or those undergoing susceptible interactions. By using an activity assay and immunoblot analysis, we identified three forms of PLD (1, 2, and 3). PLD 1 was observed only at 1 day after tissue infiltration. PLDs 2 and 3 were detected up to 3 days in all interactions. Immunoelectron microscopy studies revealed PLD to be associated predominantly with the plasma membrane. In cells undergoing a susceptible response, PLD was uniformly distributed along the plasma membrane at 3, 6, 12, and 24 hr after inoculation. However, within 12 hr after bacterial challenge in resistant interactions, PLD was clustered preferentially in membranes adjacent to bacterial cells. PMID:12239412

Young, S. A.; Wang, X.; Leach, J. E.

1996-01-01

244

Expression, crystallization and preliminary X-ray crystallographic analysis of peptide deformylase from Xanthomonas oryzae pv. oryzae.  

PubMed

Peptide deformylase (PDF) catalyzes the removal of the N-formyl group from the N-terminus of newly synthesized polypeptides; this process is crucial for cell survival. As it is an antibacterial drug target against Xanthomonas oryzae pv. oryzae (Xoo), PDF from Xoo was cloned, expressed, purified and crystallized. Native PDF crystals diffracted to 2.7 A resolution and belonged to the hexagonal space group P6(1)22, with unit-cell parameters a = b = 59.0, c = 266.3 A. One monomer is present in the asymmetric unit, with a corresponding crystal volume per protein weight of 3.50 A(3) Da(-1) and a solvent content of 64.9%. PMID:18997334

Ngo, Phuong-Thuy Ho; Kim, Jin-Kwang; Kim, Hyesoon; Jung, Junho; Ahn, Yeh-Jin; Kim, Jeong-Gu; Lee, Byoung-Moo; Kang, Lin-Woo

2008-11-01

245

Targeting NADPH oxidases in vascular pharmacology  

PubMed Central

Oxidative stress is a molecular dysregulation in reactive oxygen species (ROS) metabolism, which plays a key role in the pathogenesis of atherosclerosis, vascular inflammation and endothelial dysfunction. It is characterized by a loss of nitric oxide (NO) bioavailability. Large clinical trials such as HOPE and HPS have not shown a clinical benefit of antioxidant vitamin C or vitamin E treatment, putting into question the role of oxidative stress in cardiovascular disease. A change in the understanding of the molecular nature of oxidative stress has been driven by the results of these trials. Oxidative stress is no longer perceived as a simple imbalance between the production and scavenging of ROS, but as a dysfunction of enzymes involved in ROS production. NADPH oxidases are at the center of these events, underlying the dysfunction of other oxidases including eNOS uncoupling, xanthine oxidase and mitochondrial dysfunction. Thus NADPH oxidases are important therapeutic targets. Indeed, HMG-CoA reductase inhibitors (statins) as well as drugs interfering with the renin-angiotensin-aldosterone system inhibit NADPH oxidase activation and expression. Angiotensin-converting enzyme (ACE) inhibitors, AT1 receptor antagonists (sartans) and aliskiren, as well as spironolactone or eplerenone, have been discussed. Molecular aspects of NADPH oxidase regulation must be considered, while thinking about novel pharmacological targeting of this family of enzymes consisting of several homologs Nox1, Nox2, Nox3, Nox4 and Nox5 in humans. In order to properly design trials of antioxidant therapies, we must develop reliable techniques for the assessment of local and systemic oxidative stress. Classical antioxidants could be combined with novel oxidase inhibitors. In this review, we discuss NADPH oxidase inhibitors such as VAS2870, VAS3947, GK-136901, S17834 or plumbagin. Therefore, our efforts must focus on generating small molecular weight inhibitors of NADPH oxidases, allowing the selective inhibition of dysfunctional NADPH oxidase homologs. This appears to be the most reasonable approach, potentially much more efficient than non-selective scavenging of all ROS by the administration of antioxidants. PMID:22405985

Schramm, Agata; Matusik, Pawe?; Osmenda, Grzegorz; Guzik, Tomasz J

2012-01-01

246

Heme/copper terminal oxidases  

SciTech Connect

Spatially well-organized electron-transfer reactions in a series of membrane-bound redox proteins form the basis for energy conservation in both photosynthesis and respiration. The membrane-bound nature of the electron-transfer processes is critical, as the free energy made available in exergonic redox chemistry is used to generate transmembrane proton concentration and electrostatic potential gradients. These gradients are subsequently used to drive ATP formation, which provides the immediate energy source for constructive cellular processes. The terminal heme/copper oxidases in respiratory electron-transfer chains illustrate a number of the thermodynamic and structural principles that have driven the development of respiration. This class of enzyme reduces dioxygen to water, thus clearing the respiratory system of low-energy electrons so that sustained electron transfer and free-energy transduction can occur. By using dioxygen as the oxidizing substrate, free-energy production per electron through the chain is substantial, owing to the high reduction potential of O{sub 2} (0.815 V at pH 7). 122 refs.

Ferguson-Miller, S.; Babcock, G.T. [Michigan State Univ., East Lansing, MI (United States)] [Michigan State Univ., East Lansing, MI (United States)

1996-11-01

247

Mapping of quantitative trait loci for fiber and lignin contents from an interspecific cross Oryza sativa × Oryza rufipogon  

Microsoft Academic Search

Rice straw is always regarded as a by-product of rice production, but it could be a significant energy source for ruminant\\u000a animals. Knowledge of the genetic variation and genetic architecture of cell wall traits will facilitate rice breeders by\\u000a improving relevant traits through selective breeding and genetic engineering. The common wild rice, Oryza rufipogon Griff., which is considered to be

Jian-kun Xie; Xiang-li Kong; Jie Chen; Biao-lin Hu; Piao Wen; Jie-yun Zhuang; Jin-song Bao

2011-01-01

248

Evidence for HrpXo-Dependent Expression of Type II Secretory Proteins in Xanthomonas oryzae pv. oryzae  

PubMed Central

Xanthomonas oryzae pv. oryzae is a causal agent of bacterial leaf blight of rice. Recently, an efficient hrp-inducing medium, XOM2, was established for this bacterium. In this medium, more than 10 proteins were secreted from the wild-type strain of X. oryzae pv. oryzae. Many of these proteins disappeared or decreased in amount in culture on XOM2 when incubated with the strain that has a mutation in the hrp regulatory gene. Interestingly, the secretory protein profile of a mutant lacking a type III secretion system (TTSS), components of which are encoded by hrp genes, was similar to that of the wild-type strain except that a few proteins had disappeared. This finding suggests that many HrpXo-dependent secretory proteins are secreted via systems other than the TTSS. By isolating mutant strains lacking a type II secretion system, we examined this hypothesis. As expected, many of the HrpXo-dependent secretory proteins disappeared or decreased when the mutant was cultured in XOM2. By determining the N-terminal amino acid sequence, we identified one of the type II secretory proteins as a cysteine protease homolog, CysP2. Nucleotide sequence analysis revealed that cysP2 has an imperfect plant-inducible-promoter box, a consensus sequence which HrpXo regulons possess in the promoter region, and a deduced signal peptide sequence at the N terminus. By reverse transcription-PCR analysis and examination of the expression of CysP2 by using a plasmid harboring a cysP2::gus fusion gene, HrpXo-dependent expression of CysP2 was confirmed. Here, we reveal that the hrp regulatory gene hrpXo is also involved in the expression of not only hrp genes and type III secretory proteins but also some type II secretory proteins. PMID:14973015

Furutani, Ayako; Tsuge, Seiji; Ohnishi, Kouhei; Hikichi, Yasufumi; Oku, Takashi; Tsuno, Kazunori; Inoue, Yasuhiro; Ochiai, Hirokazu; Kaku, Hisatoshi; Kubo, Yasuyuki

2004-01-01

249

Cervical Intraepithelial Neoplasia Is Associated with Increased Polyamine Oxidase and Diamine Oxidase Concentrations in Cervical Mucus  

Microsoft Academic Search

Objective. The aim of this study was to establish whether reactive oxygen species, generated during oxidation of amines, catalyzed by polyamine oxidase (PAO) and diamine oxidase (DAO) in cervical secretions may play a role in the etiology of cervical cancer.Methods. Cervical mucus was obtained from women attending the gynecological outpatient department: 139 with and 154 without cytological evidence of cervical

M. S. Rogers; S. F. Yim; K. C. Li; C. C. Wang; M. Arumanayagam

2002-01-01

250

Allokutzneria oryzae sp. nov., isolated from rhizospheric soil of Oryza sativa L.  

PubMed

The taxonomic status of a rhizospheric soil actinomycete, designated R8-39(T), was established using a polyphasic approach. The organism had phenotypic and morphological characteristics consistent with its classification in the genus Allokutzneria. Phylogenetic analysis based on an almost complete 16S rRNA gene sequence showed that the strain formed a monophyletic clade with the type strains of members of the genus Allokutzneria. Strain R8-39(T) displayed the highest levels of 16S rRNA gene sequence similarity to Allokutzneria albata DSM 44149(T) (98.8%) and Allokutzneria multivorans YIM 120521(T) (98.3%). However, the DNA-DNA hybridization values between strain R8-39(T) and A. albata and A. multivorans were clearly below the 70% threshold. The organism was found to have chemical characteristics consistent with its classification in the genus Allokutzneria. Whole-cell hydrolysates contained meso-diaminopimelic acid, arabinose, galactose, glucose, mannose, rhamnose and ribose. The main menaquinone was MK-9(H4). No mycolic acid was detected. The G+C content of the genomic DNA was 71.8 mol%. In addition, strain R8-39(T) had a phenotypic profile that readily distinguished it from recognized representatives of the genus Allokutzneria. It is evident from the combined genotypic and phenotypic properties that strain R8-39(T) represents a novel species of the genus Allokutzneria. The proposed name for this species is Allokutzneria oryzae sp. nov.; the type strain is R8-39(T) ( = BCC 60399(T) = NBRC 109649(T)). PMID:25052392

Duangmal, Kannika; Poomthongdee, Nalin; Pathom-aree, Wasu; Takč, Akira; Thamchaipenet, Arinthip; Matsumoto, Atsuko; Takahashi, Yoko

2014-10-01

251

Purification and partial biochemical characterization of polyphenol oxidase from mango (Mangifera indica cv. Manila).  

PubMed

Polyphenol oxidase (PPO) is an enzyme widely distributed in the plant kingdom that has been detected in most fruits and vegetables. PPO was extracted and purified from Manila mango (Mangifera indica), and its biochemical properties were studied. PPO was purified 216-fold by hydrophobic interaction and ion exchange chromatography. PPO was purified to homogeneity, and the estimated PPO molecular weight (MW) by SDS-PAGE was ?31.5 kDa. However, a MW of 65 kDa was determined by gel filtration, indicating a dimeric structure for the native PPO. The isolated PPO showed the highest affinity to pyrogallol (Km = 2.77 mM) followed by 4-methylcatechol (Km = 3.14 mM) and catechol (Km = 15.14 mM). The optimum pH for activity was 6.0. PPO was stable in the temperature range of 20-70 °C. PPO activity was completely inhibited by tropolone, ascorbic acid, sodium metabisulfite, and kojic acid at 0.1 mM. PMID:25211397

Palma-Orozco, Gisela; Marrufo-Hernández, Norma A; Sampedro, José G; Nájera, Hugo

2014-10-01

252

Characterization of germin-like protein with polyphenol oxidase activity from Satsuma mandarine.  

PubMed

Polyphenol oxidases (PPOs) catalyzing the oxygen dependent oxidation of phenols to quinones are ubiquitously distributed in plants and are assumed to be involved in plant defense against pests and pathogens. A protein with high PPO activity was identified in Satsuma mandarine, extracted with Tris-HCl buffer, purified by salt precipitation and column chromatography, and characterized by mass spectrometry as germin-like protein (GLP), which belongs to pathogenesis related protein (PR) family. In the present study, the structure and enzymatic properties of GLP were characterized using spectroscopy methods. Based on native PAGE analysis, the molecular weight of GLP was estimated to be 108 kDa and GLP was identified as a pentamer containing five subunits of 22 kDa. The optimum pH and temperature for PPO catalyzing activity of GLP was 6.5 and 65°C, respectively. Kinetic constants were 0.0365 M and 0.0196 M with the substrates catechol and pyrogallol, respectively. The structural characterization of GLP provided better insights into the regions responsible for its PPO activity. PMID:24845377

Cheng, Xi; Huang, Xingjian; Liu, Siyu; Tang, Mi; Hu, Wanfeng; Pan, Siyi

2014-07-01

253

Study of ceruloplasmin oxidase activity. The effect of pH.  

PubMed

To find out the mechanism of ceruloplasmin (CP) oxidase activity CP interaction with organic substrates adrenaline (AD), catechol, p-phenylenediamine) and Fe2+ was investigated. CP was shown to interact with the above substrates according to the Theorell-Chance mechanism to form a kinetically insignificant ternary complex. The oxygen molecule binds first to CP followed by the molecule of electron donor: the inhibition of enzymatic oxidation by the reaction product is competitive. The effects of pH on kinetic parameters (Ksm, Vs) of oxidation reactions of AD and Fe2+ in the presence of CP were examined. AD was shown to be able to bind both to the protonated and to the non-protonated form of CP whereas Fe2+ interacts only with the protonated form: the rate of catalytic event (Vs) is influenced by pH in the presence of AD whereas in the presence of Fe2+ only binding to CP (Ksm) is affected by pH. Kinetic schemes describing the order of binding of hydrogen ions in the course of above reactions are proposed. PMID:2369410

Saenko, E L; Siverina, O B; Basevich, V V; Yaropolov, A I

1990-01-01

254

Expression of a Rhizopus oryzae lipase in Pichia pastoris under control of the nitrogen source-regulated formaldehyde dehydrogenase promoter.  

PubMed

A Rhizopus oryzae lipase gene has been expressed in Pichia pastoris as a reporter using the formaldehyde dehydrogenase 1 promoter (PFLD1) of this organism, which has been reported to be strongly and independently induced by either methanol as sole carbon source or methylamine as sole nitrogen source. Levels of lipase expressed and secreted under the control of the PFLD1 at different induction conditions have been compared to those obtained with the commonly used alcohol oxidase 1 promoter (PAOX1) in small (shake flask) and 1l bioreactor batch cultures. PFLD1-controlled heterologous gene expression was strongly repressed by excess of either glycerol or glucose-but not sorbitol-during growth using methylamine both as sole nitrogen source and inducing substrate. Co-induction of PFLD1 with methanol and methylamine resulted in a synergistic effect on extracellular lipase expression levels. In all tested conditions, the substitution of ammonium for methylamine as carbon source provoked a clear decrease in the specific growth rate and yield of biomass per gram of carbon source. Overall, this study demonstrates that the PFLD1 promoter is at least as efficient as the PAOX1 for extracellular expression of heterologous proteins in P. pastoris bioreactor cultures and provides a first basis for the further design of methanol-free high cell density fed-batch cultivation strategies for controlled overproduction of foreign proteins in P. pastoris. PMID:15063618

Resina, David; Serrano, Alícia; Valero, Francisco; Ferrer, Pau

2004-04-01

255

Polymer-supported sulfonated catechol and linear catechol amide ligands and their use in selective metal ion removal and recovery from aqueous solutions  

DOEpatents

The present invention concerns the synthesis of several biomimetically important polymer-supported, sulfonated catechol (PS-CATS), sulfonated bis-catechol linear amide (PS-2-6-LICAMS) and sulfonated 3,3-linear tris-catechol amide (PS-3,3-LICAMS) ligands, which chemically bond to modified 6% crosslinked macroporous polystyrene-divinylbenzene beads (PS-DVB). These polymers are useful for the for selective removal and recovery of environmentally and economically important metal ions from aqueous solution, as a function of pH. The Fe{sup 3+} ion selectivity shown for PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads in competition with a similar concentration of Cu{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, Ni{sup 2+}, Mg{sup 2+}, Al{sup 3+}, and Cr{sup 3+} ions at pH 1--3. Further, the metal ion selectivity is changed at higher pH values in the absence of Fe{sup 3+} (for example, Hg{sup 2+} at pH 3). The rates of selective removal and recovery of the trivalent metal ions, e.g. Fe{sup 3+}, Al{sup 3+} ion etc. with the PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads use determined are useful as well as equilibrium selectivity coefficient (K{sub m}) values for all metal competition studies. The chelate effect for the predisposed octahedral PS-3,3-LICAMS polymer pendant ligand is the reason that this ligand has a more pronounced selectivity for Fe{sup 3+} ion in comparison to the PS-CATS polymer beads. The predisposed square planar PS-2-6-Mn{sup 2+}, Ni{sup 2+}, and Mg{sup 2+}, than either PS-CATS or PS-3,3-LICAMS. However, Fe{sup 3+} ion still dominates in competition with other divalent and trivalent metal ions. In the absence of Fe{sup 3+}, the polymer ligand is selective for Al{sup 3+}, Cu{sup 2+} or Hg{sup 2+}. The changing of the cavity size from two CH{sub 2} groups to six CH{sub 2} groups in the PS-2-6-LICAMS polymer pendant ligand series does not effect the order of metal ion selectivity. 9 figs.

Fish, R.H.

1997-04-22

256

Polymer-supported sulfonated catechol and linear catechol amide ligands and their use in selective metal ion removal recovery from aqueous solutions  

DOEpatents

The present invention concerns the synthesis of several biomimetically important polymer-supported, sulfonated catechol (PS-CATS), sulfonated bis-catechol linear amide (PS-2-6-LICAMS) and sulfonated 3,3-linear tris-catechol amide (PS-3,3-LICAMS) ligands, which chemically bond to modified 6% crosslinked macroporous polystyrene-divinylbenzene beads (PS-DVB). These polymers are useful for the for selective removal and recovery of environmentally and economically important metal ions from aqueous solution, as a function of pH. The Fe.sup.3+ ion selectivity shown for PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads in competition with a similar concentration of Cu.sup.2+, Zn.sup.2+, Mn.sup.2+, Ni.sup.2+, Mg.sup.2+, Al.sup.3+, and Cr.sup.3+ ions at pH 1-3. Further, the metal ion selectivity is changed at higher pH values in the absence of Fe.sup.3+ (for example, Hg.sup.2+ at pH 3). The rates of selective removal and recovery of the trivalent metal ions, e.g. Fe.sup.3+ Al.sup.3+ ion etc. with the PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads used determined are useful as well as equilibrium selectivity coefficient (K.sub.m) values for all metal competition studies. The chelate effect for the predisposed octahedral PS-3,3-LICAMS polymer pendant ligand is the reason that this ligand has a more pronounced selectivity for Fe.sup.3+ ion in comparison to the PS-CATS polymer beads. The predisposed square planar PS-2,6-LICAMS series of polymer pendant ligands are more selective to divalent metal ions Cu.sup.2+, Zn.sup.2+, Mn.sup.2+, Ni.sup.2+, and Mg.sup.2+, than either PS-CATS or PS-3,3-LICAMS. However, Fe.sup.3+ ion still dominates in competition with other divalent and trivalent metal ions. In the absence of Fe.sup.3+, the polymer ligand is selective for Al.sup.3+, Cu.sup.2+ or Hg.sup.2+. The changing of the cavity size from two CH.sub.2 groups to six CH.sub.2 groups in the PS-2-6-LICAMS polymer pendant ligand series does not effect the order of metal ion selectivity.

Fish, Richard H. (Berkeley, CA)

1998-01-01

257

Polymer-supported sulfonated catechol and linear catechol amide ligands and their use in selective metal ion removal recovery from aqueous solutions  

DOEpatents

The present invention concerns the synthesis of several biomimetically important polymer-supported, sulfonated catechol (PS-CATS), sulfonated bis-catechol linear amide (PS-2-6-LICAMS) and sulfonated 3,3-linear tris-catechol amide (PS-3,3-LICAMS) ligands, which chemically bond to modified 6% crosslinked macroporous polystyrene-divinylbenzene beads (PS-DVB). These polymers are useful for the for selective removal and recovery of environmentally and economically important metal ions from aqueous solution, as a function of pH. The Fe{sup 3+} ion selectivity shown for PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads in competition with a similar concentration of Cu{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, Ni{sup 2+}, Mg{sup 2+}, Al{sup 3+}, and Cr{sup 3+} ions at pH 1--3. Further, the metal ion selectivity is changed at higher pH values in the absence of Fe{sup 3+} (for example, Hg{sup 2+} at pH 3). The rates of selective removal and recovery of the trivalent metal ions, e.g. Fe{sup 3+}, Al{sup 3+} ion etc. with the PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads used determined are useful as well as equilibrium selectivity coefficient (K{sub m}) values for all metal competition studies. The chelate effect for the predisposed octahedral PS-3,3-LICAMS polymer pendant ligand is the reason that this ligand has a more pronounced selectivity for Fe{sup 3+} ion in comparison to the PS-CATS polymer beads. The predisposed square planar PS-2,6-LICAMS series of polymer pendant ligands are more selective to divalent metal ions Cu{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, Ni{sup 2+}, and Mg{sup 2+}, than either PS-CATS or PS-3,3-LICAMS. However, Fe{sup 3+} ion still dominates in competition with other divalent and trivalent metal ions. In the absence of Fe{sup 3+}, the polymer ligand is selective for Al{sup 3+}, Cu{sup 2+} or Hg{sup 2+}. The changing of the cavity size from two CH{sub 2} groups to six CH{sub 2} groups in the PS-2-6-LICAMS polymer pendant ligand series does not effect the order of metal ion selectivity. 9 figs.

Fish, R.H.

1998-11-10

258

Polymer-supported sulfonated catechol and linear catechol amide ligands and their use in selective metal ion removal and recovery from aqueous solutions  

DOEpatents

The present invention concerns the synthesis of several biomimetically important polymer-supported, sulfonated catechol (PS-CATS), sulfonated bis-catechol linear amide (PS-2-6-LICAMS) and sulfonated 3,3-linear tris-catechol amide (PS-3,3-LICAMS) ligands, which chemically bond to modified 6% crosslinked macroporous polystyrene-divinylbenzene beads (PS-DVB). These polymers are useful for the for selective removal and recovery of environmentally and economically important metal ions from aqueous solution, as a function of pH. The Fe.sup.3+ ion selectivity shown for PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads in competition with a similar concentration of Cu.sup.2+, Zn.sup.2+, Mn.sup.2+, Ni.sup.2+,Mg.sup.2+, Al.sup.3+, and Cr.sup.3+ ions at pH 1-3. Further, the metal ion selectivity is changed at higher pH values in the absence of Fe.sup.3+ (for example, Hg.sup.2+ at pH 3). The rates of selective removal and recovery of the trivalent metal ions, e.g. Fe.sup.3+ Al.sup.3+ ion etc. with the PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads use determined are useful as well as equilibrium selectivity coefficient (K.sub.m) values for all metal competition studies. The chelate effect for the predisposed octahedral PS-3,3-LICAMS polymer pendant ligand is the reason that this ligand has a more pronounced selectivity for Fe.sup.3+ ion in comparison to the PS-CATS polymer beads. The predisposed square planar PS-2-6-Mn.sup.2+, Ni.sup.2+, and Mg.sup.2+, than either PS-CATS or PS-3,3-LICAMS. However, Fe.sup.3+ ion still dominates in competition with other divalent and trivalent metal ions. In the absence of Fe.sup.3+, the polymer ligand is selective for Al.sup.3+, Cu.sup.2+ or Hg.sup.2+. The changing of the cavity size from two CH.sub.2 groups to six CH.sub.2 groups in the PS-2-6-LICAMS polymer pendant ligand series does not effect the order of metal ion selectivity.

Fish, Richard H. (Berkeley, CA)

1997-01-01

259

Dose rate effect of gamma irradiation on phenolic compounds, polyphenol oxidase, and browning of mushrooms (Agaricus bisporus).  

PubMed

To enhance the shelf life of edible mature mushrooms, Agaricus bisporus, 2 kGy ionizing treatments were applied at two different dose rates: 4.5 kGy/h (I(-)) and 32 kGy/h (I(+)). Both I(+) and I(-) showed a 2 and 4 day shelf-life enhancement compared to the control (C). Before day 9, no significant difference (p>0.05) in L value was detected in irradiated mushrooms. However, after day 9, the highest observed L value (whiteness) was obtained for the mushrooms irradiated in I(-). Analyses of phenolic compounds revealed that mushrooms in I(-) contained more phenols than I(+) and C, the latter containing the lower level of phenols. The fluctuation of the precursors of glutaminyl-4-hydroxyaniline (GHB) was less in I(-) than in I(+). The polyphenol oxidase (PPO) activities of irradiated mushrooms, analyzed via catechol oxidase, dopa oxidase, and tyrosine hydroxylase substrates, were found to be significantly lowered (p = 0.05) compared to C, with a further decrease in I(+). Analyses of the enzymes indicated that PPO activity was lower in I(+), contrasting with its lower phenols concentration. The observation of mushrooms' cellular membranes, by electronic microscopy, revealed a better preserved integrity in I(-) than in I(+). It is thus assumed that the browning effect observed in I(+) was caused by both the decompartmentation of vacuolar phenol and the entry of molecular oxygen into the cell cytoplasm. The synergetic effect of the residual active PPO and the molecular oxygen, in contact with the phenols, allowed an increased oxidation rate and, therefore, a more pronounced browning I(+) than in I(-). PMID:10552523

Beaulieu, M; D'Aprano, M B; Lacroix, M

1999-07-01

260

Oral treatment with the NADPH oxidase antagonist apocynin mitigates clinical and pathological features of parkinsonism in the MPTP marmoset model.  

PubMed

This study evaluates the therapeutic efficacy of the NADPH oxidase inhibitor apocynin, isolated as principal bioactive component from the medicinal plant Picrorhiza kurroa, in a marmoset MPTP model of Parkinson's disease (PD). The methoxy-substituted catechol apocynin has a similar structure as homovanillic acid (HVA), a metabolite of dopamine (DA). Apocynin acquires its selective inhibitory capacity of the reactive oxygen species generating NADPH oxidase via metabolic activation by myeloperoxidase (MPO). As MPO is upregulated in activated brain microglia cells of PD patients and in MPTP animal models, the conditions for metabolic activation of apocynin and inhibition of microglia NADPH oxidase are in place. Marmoset monkeys received oral apocynin (100 mg/kg; p.o.) (n?=?5) or Gum Arabica (controls; n?=?5) three times daily until the end of the study, starting 1 week before PD induction with MPTP (1 mg/kg?s.c. for 8 days). Parkinsonian symptoms, motor function, home-cage activity and body weight were monitored to assess the disease development and severity. Post-mortem numbers of the tyrosine hydroxylase expressing DA neurons in the substantia nigra were counted. During the MPTP injections, apocynin limited the body weight loss and relieved parkinsonian symptoms compared to controls (Linear regression, P?

Philippens, Ingrid H C H M; Wubben, Jacqueline A; Finsen, Bente; 't Hart, Bert A

2013-06-01

261

Aspergillus oryzae NRRL 35191 from coffee, a non-toxigenic endophyte with the ability to synthesize kojic acid  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aspergillus oryzae was isolated as an endophyte from coffee leaves and found to produce kojic acid in culture. When inoculated in cacao seedlings (Theobroma cacao L.), A. oryzae grew endophytically and synthesize kojic acid in planta. Cacao seedlings inoculated with A. oryzae produced higher levels...

262

Codon Optimization Increases Steady-State mRNA Levels in Aspergillus oryzae Heterologous Gene Expression  

Microsoft Academic Search

We investigated the effect of codon optimization on the expression levels of heterologous proteins in Aspergillus oryzae, using the mite allergen De rf7a s amodel protein. A codon-optimized Der f 7 gene was synthesized according to the frequency of codon usage in A. oryzae by recursive PCR. Both native and optimized Der f 7 genes were expressed under the control

Masafumi Tokuoka; Mizuki Tanaka; Kazuhisa Ono; Shinobu Takagi; Takahiro Shintani; Katsuya Gomi

2008-01-01

263

Foliar and cane rot of Arundo donax caused by Nigrospora oryzae in Europe  

Technology Transfer Automated Retrieval System (TEKTRAN)

A fungus was isolated consistently from dead shoot tips and flag leaves of Arundo donax L. (Poaceae) in France, Crete, Cyprus, Italy, Morocco, and Spain during April through September of 2003 to 2005. The fungus was identified as Nigrospora oryzae (Berk. & Br.) Petch (teleomorph Khuskia oryzae) usi...

264

Draft Genome Sequence of Weissella oryzae SG25T, Isolated from Fermented Rice Grains  

PubMed Central

Weissella oryzae was originally isolated from fermented rice grains. Here we report the draft genome sequence of the type strain of W. oryzae. This first report on the genomic sequence of this species may help identify the mechanisms underlying bacterial adaptation to the ecological niche of fermented rice grains. PMID:25013139

Tanizawa, Yasuhiro; Fujisawa, Takatomo; Mochizuki, Takako; Kaminuma, Eli; Suzuki, Yutaka; Nakamura, Yasukazu

2014-01-01

265

Isolation and Identification of Indigenous Aspergillus oryzae for Saccharification of Rice Starch  

Microsoft Academic Search

A study was undertaken to isolate an indigenous Aspergillus oryzae strain for use in saccharification of high amylose rice starch. Bread, black gram, soya grains, 'kevum', and cooked rice samples assumed to be contaminated with Aspergillus oryzae were used in the isolation. Ten pure cultures obtained by culturing and sub- culturing on Potato Dextrose Agar (PDA) were maintained on PDA

S. S. Sooriyamoorthy; K. F. S. T. Silva; M. H. W. Gunawardhane; C. K. Illeperuma

266

Pathogenic variation among isolates of Pyricularia oryzae affecting rice, wheat, and grasses in Brazil  

Microsoft Academic Search

Rice blast caused by Pyricularia oryzae occurs on wheat under natural field conditions in Brazil. Isolates of P. oryzae collected from rice, wheat and grass weeds Digitaria sanguinalis, Rhynchelytrum roseum, Pennisetum setosum and Eleusine indica were tested for virulence to 30 rice, five wheat and one barley cultivars. All isolates from rice, wheat and grass weeds were pathogenic to the

A. S. Prabhu; M. C. Filippi; N. Castro

1992-01-01

267

Identification, Biochemical Characterization, and Evolution of the Rhizopus oryzae 99-880 Polygalacturonase Gene Family  

Technology Transfer Automated Retrieval System (TEKTRAN)

A search of the recently sequenced Rhizopus oryzae strain 99-880 genome database uncovered 18 putative polygalacturonase genes with 2 genes being identical and only 1 with similarity to a previously reported R. oryzae polygalacturonase gene. The 17 different genes share 50% to greater than 90% iden...

268

Analysis of genomic variation of rice blast resistance gene Pi-ta in oryza species  

Technology Transfer Automated Retrieval System (TEKTRAN)

The resistance gene Pi-ta in rice has been deployed worldwide to prevent the infection by the blast pathogen, Magnaporthe oryzae. The genomic region spanning Pi-ta in 144 accessions composed of seven Oryza species has been sequenced to determine DNA sequence variation of Pi-ta. Presently, three si...

269

Alternatively spliced transcripts of Pi-ta blast resistance gene in Oryza sativa  

Technology Transfer Automated Retrieval System (TEKTRAN)

The Pi-ta gene in rice (Oryza sativa L.) confers resistance to races of Magnaporthe oryzae containing its cognate avirulence gene AVR-Pita. Pi-ta is a single-copy gene belonging to the nucleotide-binding site leucine-rich repeat (NBS-LRR) class of plant resistance (R) genes. In the present study, w...

270

Resistance among U.S. wheat Triticum aestivum cultivars to the wheat pathotype of Magnaporthe oryzae  

Technology Transfer Automated Retrieval System (TEKTRAN)

Magnaporthe oryzae is the causal agent of blast on several graminaceous plants. The M. oryzae population causing wheat blast has not been found outside South America. U.S. wheat production is at risk to this pathogen if introduced and established. Proactive testing of US wheat cultivars for their re...

271

Studies on Aspergillus oryzae Mutants for the Production of Single Cell Proteins from Deoiled Rice Bran  

Microsoft Academic Search

Summary Ethyl methyl sulphonate was used to induce point mutation in Aspergillus oryzae (MTCC 1846). Incubation with ethyl methyl sulphonate for 1 h resulted in 98 % killing of spores. By screening the survived colonies three hypermorphs were found (Shan1, Shan2 and Shan3). These three mutants along with the A. oryzae (MTCC 1846) were used for the production of single

Rudravaram Ravinder; Linga Venkateshwar Rao; Pogaku Ravindra

2003-01-01

272

Effect of intracerebral 6-nitronoradrenaline, an endogenous catechol-O-methyltransferase (COMT) inhibitor, on striatal dopamine metabolism in anaesthetised rats.  

PubMed

6-Nitronoradrenaline, a bioactive compound recently identified in the brain, is known to inhibit catechol-O-methyltransferase. To study its effect on dopamine metabolism, it was administered into rat striatum via a microdialysis probe. Other nitrated catechols (6-nitrodopamine, 6-nitro-DOPAC and 5-nitro-HVA) were studied for comparison. Tolcapone, a selective catechol-O-methyltransferase inhibitor, was used as a positive reference compound. Both 6-nitronoradrenaline and tolcapone increased striatal extracellular dopamine levels during the perfusion (at 100 microM concentration but not at 10 microM) and decreased the efflux of homovanillic acid. Tolcapone, but not other nitrated catechols, increased 3,4-dihydroxyphenylacetic acid efflux. None of the compounds inhibited MAO-B activity at 100 microM or lower. At 1 mM, 6-nitrodopamine inhibited MAO-B by 60%. Compared to tolcapone, other nitrated catechols were very weak COMT inhibitors in vitro. Neither tolcapone nor 6-nitronoradrenaline modified the metabolism of L-dopa which was given peripherally. In binding studies, both 6-nitronoradrenaline and other nitrocatechols failed to affect the dopamine transporter even at high micromolar concentrations. In conclusion, exogenous 6-nitronoradrenaline can act as a COMT inhibitor in the striatum and elevate striatal dopamine levels without inhibiting dopamine reuptake. Whether endogenous 6-nitronoradrenaline can be formed also in vivo in the striatum and act as a regulator of dopaminergic tone remains to be determined. PMID:11489299

Huotari, M; Passlin, M; Nordberg, H L; Forsberg, M; Kotisaari, S; Tuomisto, L; Shintani, F; Tanaka, K F; Reenilä, I; Laitinen, K; Männistö, P T

2001-08-15

273

Catechol, a bioactive degradation product of salicortin, reduces TNF-? induced ICAM-1 expression in human endothelial cells.  

PubMed

The phenolic glucoside salicortin was isolated from a Willow bark extract, and its ability to reduce the TNF- ? induced ICAM-1 expression (10 ng/mL, 30 min pretreatment with salicortin) was tested IN VITRO on human microvascular endothelial cells (HMEC-1). After 24 h, 25 ľM salicortin decreased the TNF- ? induced ICAM-1 expression to 65.9 % compared to cells which were treated only with TNF- ?. In parallel, the stability of 25 ľM salicortin under assay conditions was determined by HPLC. Within 24 h, the salicortin concentration decreased to 3.1 ľM whereas catechol, a known NF- ?B inhibitor, rose as a metabolite. After 8 h the catechol concentration was relatively constant and varied between 8.2 and 10.9 ľM. Considering this degradation in the IN VITRO test system, 10 ľM catechol was added 8 h after TNF- ? stimulation, and 16 h later the ICAM-1 expression was determined. In this setting, the ICAM-1 expression was reduced to 74.8 %. This is comparable to the effect obtained from 25 ľM salicortin and indicates that its activity is related to the generation of catechol, as salicin, saligenin, and salicylic acid are only marginally active or inactive in this test system in a concentration up to 50 ľM. These results indicate catechol as an important bioactive metabolite from salicortin. PMID:21305449

Knuth, Susanne; Schübel, Helmut; Hellemann, Martin; Jürgenliemk, Guido

2011-07-01

274

Comparison between the removal of phenol and catechol by modified montmorillonite with two novel hydroxyl-containing Gemini surfactants.  

PubMed

Na-montmorillonites were modified with two novel hydroxyl-containing Gemini surfactants, 1,3-bis(hexadecyldimethylammonio)-2-hydroxypropane dichloride (BHHP) and 1,3-bis(octyldimethylammonio)-2-hydroxypropane dichloride (BOHP), via ion-exchange reaction in this study. The modified samples were characterized by X-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) spectroscopy. Phenol and catechol were removed from aqueous solution by these two kinds of organo-montmorillonites in a batch system. Important parameters have been investigated, which affect the adsorption efficiency, such as the amount of modifier, temperature, pH and contact time. The adsorption kinetics of phenol and catechol were discussed using pseudo-first-order, pseudo-second-order and intra-particle diffusion model. It indicated that the experimental data fitted very well with the pseudo-second-order kinetic model, and the equilibrium adsorption data was proved in good agreement with the Langmuir isotherm. The result also showed the adsorption capacity of catechol was higher than that of phenol in the same conditions, which might result from the extra hydroxyl in the structure of catechol. Thermodynamic quantities such as Gibbs free energy (?G°), the enthalpy (?H°), and the entropy change of sorption (?S°) were also determined. These parameters suggested the adsorption of phenol was a spontaneous and exothermic process, while the sorption of catechol was endothermic. PMID:24413053

Liu, Yuening; Gao, Manglai; Gu, Zheng; Luo, Zhongxin; Ye, Yage; Lu, Laifu

2014-02-28

275

Gas phase structure and reactivity of doubly charged microhydrated calcium(II)-catechol complexes probed by infrared spectroscopy.  

PubMed

Doubly charged microhydrated adducts formed from catechol and calcium(II) were produced in the gas phase using electrospray ionization (ESI) appearing as the most important ions in the mass spectra recorded. The gas phase structures of [Ca(catechol)2(H2O)](2+) and [Ca(catechol)2(H2O)2](2+) have been assayed by IR multiphoton dissociation (IRMPD) spectroscopy, recording their vibrational spectra in the 3450-3750 cm(-1) range (OH stretching region) and in the 900-1700 cm(-1) fingerprint spectral region. The agreement between experimental and calculated IR spectra of the selected cluster ions confirmed the suitability of the proposed geometries. In addition, quantum chemical calculations at the B3LYP/6-311+G(d,p) level of theory were performed for [Ca(catechol)2(H2O)](2+) to gain insight into the major routes of dissociation. The results suggest that loss of the water molecule is the lowest energy fragmentation channel followed by charge separation products and neutral loss of one catechol molecule, in agreement with the product ions observed upon collision-induced dissociation (CID). PMID:24963704

Butler, Matias; Mańez, Pau Arroyo; Cabrera, Gabriela M; Maître, Philippe

2014-07-10

276

Localizing NADPH Oxidase-Derived ROS  

NSDL National Science Digital Library

Reactive oxygen species (ROS) function as signaling molecules to mediate various biological responses, including cell migration, growth, and gene expression. ROS are diffusible and short-lived molecules. Thus, localizing the ROS signal at the specific subcellular compartment is essential for activating redox signaling events after receptor activation. NADPH (nicotinamide adenine dinucleotide phosphate) oxidase is one of the major sources of ROS in vasculature; it consists of a catalytic subunit (Nox1, Nox2, Nox3, Nox4, or Nox5), p22phox, p47phox, p67phox, and the small guanosine triphosphatase Rac1. Targeting of NADPH oxidase to focal complexes in lamellipodia and membrane ruffles through the interaction of p47phox with the scaffold proteins TRAF4 and WAVE1 provides a mechanism for achieving localized ROS production, which is required for directed cell migration. ROS are believed to inactivate protein tyrosine phosphatases, which concentrate in specific subcellular compartments, thereby establishing a positive feedback system that activates redox signaling pathways to promote cell movement. Additionally, ROS production may be localized through interactions of NADPH oxidase with signaling platforms associated with lipid rafts and caveolae, as well as with endosomes. There is also evidence that NADPH oxidase is found in the nucleus, indicating its involvement in redox-responsive gene expression. This review focuses on targeting of NADPH oxidase to discrete subcellular compartments as a mechanism of localizing ROS and activation of downstream redox signaling events that mediate various cell functions.

Masuko Ushio-Fukai (IL; University of Illinois College of Medicine, Chicago REV)

2006-08-22

277

Selected biochemical properties of polyphenol oxidase in butter lettuce leaves (Lactuca sativa L. var. capitata) elicited with dl-?-amino-n-butyric acid.  

PubMed

The study concentrated on changes in certain biochemical parameters of polyphenol oxidase (PPO) from lettuce leaves caused by dl-?-amino-n-butyric acid (BABA) elicitation. PPO from control plants demonstrated the highest affinity toward catechol, whereas PPO from BABA-elicited lettuce showed the highest affinity to 4-methylcatechol. The optimum temperature for enzymes from control plants was 35°C, whereas from plants elicited with 1mM BABA this was 25°C. PPO from plants elicited with BABA was also more sensitive to the tested inhibitors than PPO from control plants. l-Cysteine was the most effective inhibitor. Native gel stained for PPO activity in control samples showed two isoforms. However, in BABA-treated lettuce three bands visualising PPO activity were observed. The information obtained in this study will be valuable for the development of treatment technology and storage conditions to control undesirable browning reactions in elicited lettuce. PMID:25172730

Z?otek, Urszula; Gawlik-Dziki, Urszula

2015-02-01

278

Catechol-O-Methyltransferase (COMT): A Gene Contributing to Sex Differences in Brain Function, and to Sexual Dimorphism in the Predisposition to Psychiatric Disorders  

Microsoft Academic Search

Sex differences in the genetic epidemiology and clinical features of psychiatric disorders are well recognized, but the individual genes contributing to these effects have rarely been identified. Catechol-O-methyltransferase (COMT), which metabolizes catechol compounds, notably dopamine, is a leading candidate. COMT enzyme activity, and the neurochemistry and behavior of COMT null mice, are both markedly sexually dimorphic. Genetic associations between COMT

Paul J Harrison; Elizabeth M Tunbridge

2008-01-01

279

Ketoglutarate Transport Protein KgtP Is Secreted through the Type III Secretion System and Contributes to Virulence in Xanthomonas oryzae pv. oryzae  

PubMed Central

The phytopathogenic prokaryote Xanthomonas oryzae pv. oryzae is the causal agent of bacterial leaf blight (BB) of rice and utilizes a type III secretion system (T3SS) to deliver T3SS effectors into rice cells. In this report, we show that the ketoglutarate transport protein (KgtP) is secreted in an HpaB-independent manner through the T3SS of X. oryzae pv. oryzae PXO99A and localizes to the host cell membrane for ?-ketoglutaric acid export. kgtP contained an imperfect PIP box (plant-inducible promoter) in the promoter region and was positively regulated by HrpX and HrpG. A kgtP deletion mutant was impaired in bacterial virulence and growth in planta; furthermore, the mutant showed reduced growth in minimal media containing ?-ketoglutaric acid or sodium succinate as the sole carbon source. The reduced virulence and the deficiency in ?-ketoglutaric acid utilization by the kgtP mutant were restored to wild-type levels by the presence of kgtP in trans. The expression of OsIDH, which is responsible for the synthesis of ?-ketoglutaric acid in rice, was enhanced when KgtP was present in the pathogen. To our knowledge, this is the first report demonstrating that KgtP, which is regulated by HrpG and HrpX and secreted by the T3SS in Xanthomonas oryzae pv. oryzae, transports ?-ketoglutaric acid when the pathogen infects rice. PMID:22685129

Guo, Wei; Cai, Lu-Lu; Zou, Hua-Song; Ma, Wen-Xiu; Liu, Xi-Ling; Zou, Li-Fang; Li, Yu-Rong

2012-01-01

280

Bioinspired Copper(I) Complexes that Exhibit Monooxygenase and Catechol Dioxygenase Activity.  

PubMed

New tripodal ligand L2 featuring three different pyridyl/imidazolyl-based N-donor units at a bridgehead C atom, from which one of the imidazolyl units is separated by a phenylene linker, was synthesized and investigated with regards to copper(I) complexation. The resulting complex [(L2)Cu]OTf (2(OTf) ), the known complex [(L1)Cu]OTf (1(OTf) ; L1 differs from L2 in that it lacks the phenylene spacer) and [(L3)Cu]OTf (3(OTf) ), prepared from a known chiral, tripodal, N-donor ligand featuring pyridyl, pyrazolyl, and imidazolyl donors, were tested as catalysts for the oxidation of sodium 2,4-di-tert-butylphenolate (NaDTBP) with O2 . Indeed, they mediated NaDTBP oxidation to give mainly the corresponding catecholate and quinone (Q). None of the complexes 1(OTf) , 2(OTf) , and 3(OTf) is superior to the others, as yields were comparable and, if the presence of protons is guaranteed by concomitant addition of the phenol DTBP, the oxidation can also be performed catalytically. For all complexes stoichiometric oxidations under certain conditions (concentrated solutions, high NaDTBP content) were found to also generate products typical for metal-mediated intradiol cleavage of the catecholate with O2 . As shown representatively for 1(OTf) this dioxygenation sets in at a later stage of the reaction. Initially a copper species responsible for the monooxygenation must form from 1(OTf) /NaDTBP/O2 , and only thereafter is the copper species responsible for dioxygenation formed and consumes Q as substrate. Hence, under these circumstances complexes 1(OTf) -3(OTf) show both monooxygenase and catechol dioxygenase activity. PMID:25395055

Arnold, Aline; Metzinger, Ramona; Limberg, Christian

2014-11-13

281

Induction of glucose oxidase, catalase, and lactonase in Aspergillus niger  

Microsoft Academic Search

The induction of glucose oxidase, catalase, and lactonase activities was studied both in wild-type and in glucose oxidase regulatory and structural mutants of Aspergillus niger. The structural gene for glucose oxidase was isolated and used for Northern analysis and in transformation experiments using various gox mutations. Wild-type phenotype could be restored in the glucose oxidase-negative mutant (goxC) by transformation with

Cor F. B. Witteveen; Hetty C. van den Broeck; Frank A. C. van Engelenburg; Leo H. de Graaff; Marcel H. B. C. Hillebrand; Peter J. Schaap; Jaap Visser

1993-01-01

282

Extraction of metals from metal ion-catechol-quaternary base systems.  

PubMed

Methods are given for the extraction of iron(III), molybdenum(VI), titanium(IV), niobium(V), vanadium(IV), uranium(VI) and tungsten(VI) as ternary complexes with catechol and a quaternary cation such as n-butyltriphenylphosphonium, n-propyltriphenylphosphonium, tetraphenylarsonium, cetylpyridinium, cetyltrimethylammonium and 2,3,5-triphenyltetrazolium, the solvent being chloroform. By use of masking agents and pH control, some of these elements can be separated from each other by this means. PMID:18960382

Vrchlabský, M; Sommer, L

1968-09-01

283

Catechol Redox Induced Formation of Metal Core-Polymer Shell Nanoparticles  

PubMed Central

A novel strategy was developed to synthesize polymer-coated metal nanoparticles (NPs) through reduction of metal cations with 3,4-dihydroxyphenylalanine (DOPA)-containing polyethylene glycol (PEG) polymers. Catechol redox chemistry was used to both synthesize metal NPs and simultaneously form a cross-linked shell of PEG polymers on their surfaces. DOPA reduced gold and silver cations into neutral metal atoms, producing reactive quinones that covalently cross-linked the PEG molecules around the surface of the NP. Importantly, these PEG-functionalized metal NPs were stable in physiological ionic strengths and under centrifugation, and hold broad appeal since they absorb and scatter light in aqueous solutions. PMID:21666825

Black, Kvar C.L.; Liu, Zhongqiang; Messersmith, Phillip B.

2011-01-01

284

Molecular cytotoxic mechanisms of catecholic polychlorinated biphenyl metabolites in isolated rat hepatocytes.  

PubMed

Polychlorinated biphenyl (PCB) and PCB metabolites are highly lipophilic and accumulate easily in the lipid bilayer and fat deposits of the body. The molecular cytotoxic mechanisms of these metabolites are still not understood. The aim of the present study was to compare the cytotoxicity and toxicological properties of six dihydroxylated metabolites using isolated rat hepatocytes. All of the metabolites were more cytotoxic than 4-chlorobiphenyl (4-ClBP) and less cytotoxic than phenyl hydroquinone (PHQ). The order of cytotoxic effectiveness of catecholic metabolites expressed as LC(50) (2h) was 3',4'-diCl-2,3-diOH-biphenyl>PHQ>4'-Cl-2,5-diOH-biphenyl, 4'-Cl-2,3-diOH-biphenyl>2',5'-diCl-3,4-diOH-biphenyl>2',3'-diCl-3,4-diOH-biphenyl>3',4'-diCl-3,4-diOH-biphenyl>4'Cl-3,4-diOH-biphenyl>4'-Cl-biphenyl; showing that the positions of hydroxyl and chlorine groups were important for their hepatotoxicity and that the two 2,3-diOH congeners were the most cytotoxic. Cytotoxicity for 3,4-diOH metabolites correlated with the number and position of chlorine atoms with the more chlorine atoms being more cytotoxic. The cytotoxic order of metabolites with two chlorine atoms being 2',5'>2',3'>3',4'. Borneol, an uridine diphosphate glucuronosyltransferases (UGT) inhibitor, increased the cytotoxicity of all tested metabolites; suggesting that glucuronidation was a major mechanism of elimination of these compounds. On the other hand entacapone, a catechol-O-methyl transferase (COMT) inhibitor, only increased the cytotoxicity of 3',4'-diCl-3,4-diOH-biphenyl, 3',4'-diCl-2,3-diOH-biphenyl and 4'-Cl-2,3-diOH-biphenyl. Hepatocyte GSH was depleted (oxidized and conjugated) by these metabolites before cytotoxicity ensued in a similar order of effectiveness to their cytotoxicity with PHQ being the most effective. Hepatocyte mitochondrial membrane potential also decreased before cytotoxicity ensued with a similar order of effectiveness as their cytotoxicity. These results suggest that catecholic cytotoxicity can be attributed to mitochondrial toxicity and oxidative stress. Semiquinone or benzoquinone species were also important in the cytotoxicity of catecholic metabolites. PMID:17408604

Sadeghi-Aliabadi, Hojjat; Chan, Katie; Lehmler, Hans-Joachim; Robertson, Larry W; O'Brien, Peter J

2007-05-01

285

Bioremediation of Dyes in Textile Effluents by Aspergillus oryzae  

Microsoft Academic Search

In this study Aspergillus oryzae was utilized to remove azo dyes from aqueous solution. Physically induced in its paramorphogenic form to produce standardized\\u000a mycelial pellets, the non-autoclaved and autoclaved hyphae biomass was applied to biosorb the reactive dyes Procion Red HE7B\\u000a (PR-HE7B) and Procion Violet H3R (PV-H3R) at different pH values (2.50, 4.50, and 6.50). The best pH for biosorption

Carlos Renato Corso; Ana Carolina Maganha de Almeida

2009-01-01

286

Diamine Oxidase Activity in Plasma and Urine in Uremia  

Microsoft Academic Search

Diamine oxidase activity was measured in plasma or urine in 12 normal men, 4 men with chronic liver or heart disease, 13 men with chronic renal failure, and 12 men undergoing maintenance hemodialysis. Also in five studies in 4 patients, plasma diamine oxidase activity and total amine levels were measured at hourly intervals during a hemodialysis treatment. Plasma diamine oxidase

Chick Fai Tarn; Joel D. Kopple; Marian Wang; Marian E. Swendseid

1979-01-01

287

Decreased plasma postheparin diamine oxidase levels in celiac disease  

Microsoft Academic Search

The highest diamine oxidase activity is contained in small-bowel mucosa and, after heparin administration, the enzyme is released by the intestine into the plasma. Previous experimental studies showed that measurement of plasma postheparin diamine oxidase activity is a sensitive test for quantitating the length and severity of small-bowel mucosal injury. On this basis, we measured plasma diamine oxidase activity in

Gino Roberto Corazza; Annaida Falasca; Alessandra Strocchi; Carlo Alfonso Rossi; Giovanni Gasbarrini

1988-01-01

288

Evidence for Biotrophic Lifestyle and Biocontrol Potential of Dark Septate Endophyte Harpophora oryzae to Rice Blast Disease  

PubMed Central

The mutualism pattern of the dark septate endophyte (DSE) Harpophora oryzae in rice roots and its biocontrol potential in rice blast disease caused by Magnaporthe oryzae were investigated. Fluorescent protein-expressing H. oryzae was used to monitor the colonization pattern. Hyphae invaded from the epidermis to the inner cortex, but not into the root stele. Fungal colonization increased with root tissue maturation, showing no colonization in the meristematic zone, slight colonization in the elongation zone, and heavy colonization in the differentiation zone. H. oryzae adopted a biotrophic lifestyle in roots accompanied by programmed cell death. Real-time PCR facilitated the accurate quantification of fungal growth and the respective plant response. The biocontrol potential of H. oryzae was visualized by inoculation with eGFP-tagged M. oryzae in rice. H. oryzae protected rice from M. oryzae root invasion by the accumulation of H2O2 and elevated antioxidative capacity. H. oryzae also induced systemic resistance against rice blast. This systemic resistance was mediated by the OsWRKY45-dependent salicylic acid (SA) signaling pathway, as indicated by the strongly upregulated expression of OsWRKY45. The colonization pattern of H. oryzae was consistent with the typical characteristics of DSEs. H. oryzae enhanced local resistance by reactive oxygen species (ROS) and high antioxidative level and induced OsWRKY45-dependent SA-mediated systemic resistance against rice blast. PMID:23637814

Su, Zhen-Zhu; Mao, Li-Juan; Li, Na; Feng, Xiao-Xiao; Yuan, Zhi-Lin; Wang, Li-Wei; Lin, Fu-Cheng; Zhang, Chu-Long

2013-01-01

289

Survey of the transcriptome of Aspergillus oryzae via massively parallel mRNA sequencing  

PubMed Central

Aspergillus oryzae, an important filamentous fungus used in food fermentation and the enzyme industry, has been shown through genome sequencing and various other tools to have prominent features in its genomic composition. However, the functional complexity of the A. oryzae transcriptome has not yet been fully elucidated. Here, we applied direct high-throughput paired-end RNA-sequencing (RNA-Seq) to the transcriptome of A. oryzae under four different culture conditions. With the high resolution and sensitivity afforded by RNA-Seq, we were able to identify a substantial number of novel transcripts, new exons, untranslated regions, alternative upstream initiation codons and upstream open reading frames, which provide remarkable insight into the A. oryzae transcriptome. We were also able to assess the alternative mRNA isoforms in A. oryzae and found a large number of genes undergoing alternative splicing. Many genes and pathways that might be involved in higher levels of protein production in solid-state culture than in liquid culture were identified by comparing gene expression levels between different cultures. Our analysis indicated that the transcriptome of A. oryzae is much more complex than previously anticipated, and these results may provide a blueprint for further study of the A. oryzae transcriptome. PMID:20392818

Wang, Bin; Guo, Guangwu; Wang, Chao; Lin, Ying; Wang, Xiaoning; Zhao, Mouming; Guo, Yong; He, Minghui; Zhang, Yong; Pan, Li

2010-01-01

290

Diamine oxidase and putrescine oxidase immobilized reactors in flow injection analysis: a comparison in substrate specificity  

Microsoft Academic Search

Enzyme reactors for the determination of biogenic amines have been developed using diamine oxidase (DAO) from porcine kidney and from lentil and putrescine oxidase (PUO) from microorganism (Micrococcus roseus). Determination is based on the electrochemical oxidation of enzymatically produced H2O2 at platinum electrode poised at 600 mV versus Ag\\/AgCl. The enzymes are immobilized on controlled pore glass beads activated by

M.-A Carsol; M Mascini

1999-01-01

291

Cross talk between mitochondria and NADPH oxidases  

Microsoft Academic Search

Reactive oxygen species (ROS) play an important role in physiological and pathological processes. In recent years, a feed-forward regulation of the ROS sources has been reported. The interactions between the main cellular sources of ROS, such as mitochondria and NADPH oxidases, however, remain obscure. This work summarizes the latest findings on the role of cross talk between mitochondria and NADPH

Sergey Dikalov

2011-01-01

292

Studies on the mechanism of alcohol oxidase  

E-print Network

advanced than carbon hydrogen bond cleavage. With methanol, ethanol, and trifluoroethanol as substrates for alcohol oxidase, a single ionizable group with a pKa value of 8.3 must be deprotonated for binding and catalysis. This residue is proposed...

Menon, Vipin

2012-06-07

293

Inhibition of diamine oxidase by antimalarial drugs  

Microsoft Academic Search

The antimalarial drugs amodiaquine, quinacrine and chloroquine inhibit the catabolism of putrescine by the rat. Amodiaquine, the most potent of the three, does so in a dose-dependent fashion. This is attributed to the action in vivo of the drugs on diamine oxidase, an enzyme that is inhibited by them in vitro.

Kelvin Ma; Theodore L. Sourkes

1980-01-01

294

Postheparin-diamine oxidase (histaminase) in anaphylaxis  

Microsoft Academic Search

Summary The level of plasma postheparin-diamine oxidase was determined in two patients three days after an anaphylactic shock and was controlled four weeks, and also six months later. A decrease of the enzyme levels to about 10% of a control group was found and a slow enzyme increase to about 40% observed six months later. It seems probable that in

V. Gäng; W. Gaubitz; U. Gunzer

1975-01-01

295

Cloning and expression of A. oryzae ?-glucosidase in Pichia pastoris.  

PubMed

A ?-glucosidase gene (bgl) from Aspergillus oryzae GIF-10 was cloned, sequenced and expressed. Its full-length DNA sequence was 2,903 bp and included three introns. The full-length cDNA sequence contained an open reading frame of 2,586 nucleotides, encoding 862 amino acids with a potential secretion signal. The A. oryzae GIF-10 bgl was functionally expressed in Pichia pastoris. After 7-day induction, protein yield reached 321 mg/mL. Using salicin as the substrate, the specific activity of the purified enzyme reached 215 U/mg. The purified recombinant ?-glucosidase was a 110-kDa glycoprotein with optimum catalytic activity at pH 5.0 and 50 °C. The enzyme was stable between 20 and 60 °C, and retained 65% of its activity after being held at 60 °C for 30 min. The recombinant ?-glucosidase was relatively stable in a broad range of pHs, from 4.0 to 6.5. It showed broad specific activity, hydrolyzing a range of (1-4)-?-diglycosides and (1-4)-?-diglycosides, and Mn(2+) stimulated its activity significantly. PMID:25123895

Tang, Zizhong; Liu, Shan; Jing, Haijun; Sun, Rong; Liu, Moyang; Chen, Hui; Wu, Qi; Han, Xueyi

2014-11-01

296

Suicide inactivation of catechol 2,3-dioxygenase from Pseudomonas putida mt-2 by 3-halocatechols  

SciTech Connect

The inactivation of catechol 2,3-dioxygenase from Pseudomonas putida mt-2 by 3-chloro- and 3-fluorocatechol and the iron-chelating agent Tiron (catechol-3,5-disulfonate) was studied. Whereas inactivation by Tiron is an oxygen-independent and mostly reversible process, inactivation by the 3-halocatechols was only observed in the presence of oxygen and was largely irreversible. The rate constants for inactivation (K/sub 2/) were 1.62 x 10/sup -3/ sec/sup -1/ for 3-chlorocatechol and 2.38 x 10/sup -3/ sec/sup -1/ for 3-fluorocatechol. The inhibitor constants (K/sub i/) were 23 ..mu..M for 3-chlorocatechol and 17 ..mu..M for 3-fluorocatechol. The kinetic data for 3-fluorocatechol could only be obtained in the presence of 2-mercaptoethanol. Besides inactivated enzyme, some 2-hydroxyhexa-2,4-dienoic acid as the actual suicide product of meta-cleavage. A side product of 3-fluorocatechol cleavage is a yellow compound with the spectral characteristics of a 2-hydroxy-6-oxohexa-2,4-dienoci acid indicating 1,6-cleavage. Rates of inactivation by 3-fluorocatechol were reduced in the presence of superoxide dismutase, catalase, formate, and mannitol, which implies that superoxide anion, hydrogen peroxide, and hydroxyl radical exhibit additional inactivation. 64 references.

Bartels, I.; Knackmuss, H.J.; Reineke, W.

1984-03-01

297

Fine-tuning of catalytic properties of catechol 1,2-dioxygenase by active site tailoring.  

PubMed

Catechol 1,2-dioxygenases and chlorocatechol dioxygenases are Fe(III)-dependent enzymes that do not require a reductant to perform the ortho cleavage of the aromatic ring. The reaction mechanism is common to the two enzymes, and active-site residues must play a key role in the fine-tuning of specificity. Protein engineering was applied for the first time to the catalytic pocket of a catechol 1,2-dioxygenase by site-specific and site-saturation mutagenesis with the purpose of redesigning the pocket shape for improved catalysis on bulky derivatives. Mutants were analysed for changes in kinetic parameters: variants for residue 69 show an inversion of specificity with a preference towards 4-chlorocatechol (decrease of K(M) by a factor of 20) and activity on the rarely recognised substrate 4,5-dichlorocatechol, thus creating a novel, engineered chlorocatechol dioxygenase. A L69A substitution conveys gain-of-function activity towards 4-tert-butylcatechol. Mutations of position 72 enhance k(cat) towards chlorinated substrates. The biphasic Arrhenius plot observed in A72S suggests the involvement of a dynamic switch in the fine regulation of the enzyme. PMID:19301316

Caglio, Raffaella; Valetti, Francesca; Caposio, Patrizia; Gribaudo, Giorgio; Pessione, Enrica; Giunta, Carlo

2009-04-17

298

Efficient expression of a Phanerochaete chrysosporium manganese peroxidase gene in Aspergillus oryzae  

SciTech Connect

A manganese peroxidase (mnp1) from Phanerochaete chrysosporium was efficiently expressed in Aspergillus oryzae. Expression was achieved by fusing the mature cDNA of mnp1 with the A. oryzae Taka amylase promoter and secretion signal. The 3{prime} untranslated region of the glucoamylase gene of Asperigillus awamori provided the terminator. The recombinant protein (rMnP) was secreted in an active form, permitting rapid detection and purification. Physical and kinetic properties of rMnP were similar to those of the native protein. The A. oryzae expression system is well suited for both mechanistic and site-directed mutagenesis studies. 34 refs., 7 figs., 1 tab.

Stewart, P. [Univ. of Wisconsin, Madison, WI (United States); Whitwam, R.E.; Tien, Ming [Pennsylvanis State Univ., University Park, PA (United States)] [and others

1996-03-01

299

Cell Wall Degrading Enzyme Induced Rice Innate Immune Responses Are Suppressed by the Type 3 Secretion System Effectors XopN, XopQ, XopX and XopZ of Xanthomonas oryzae pv. oryzae  

PubMed Central

Innate immune responses are induced in plants and animals through perception of Damage Associated Molecular Patterns. These immune responses are suppressed by pathogens during infection. A number of studies have focussed on identifying functions of plant pathogenic bacteria that are involved in suppression of Pathogen Associated Molecular Pattern induced immune responses. In comparison, there is very little information on functions used by plant pathogens to suppress Damage Associated Molecular Pattern induced immune responses. Xanthomonasoryzae pv. oryzae, a gram negative bacterial pathogen of rice, secretes hydrolytic enzymes such as LipA (Lipase/Esterase) that damage rice cell walls and induce innate immune responses. Here, we show that Agrobacterium mediated transient transfer of the gene for XopN, a X. oryzae pv. oryzae type 3 secretion (T3S) system effector, results in suppression of rice innate immune responses induced by LipA. A xopN- mutant of X. oryzae pv. oryzae retains the ability to suppress these innate immune responses indicating the presence of other functionally redundant proteins. In transient transfer assays, we have assessed the ability of 15 other X. oryzae pv. oryzae T3S secreted effectors to suppress rice innate immune responses. Amongst these proteins, XopQ, XopX and XopZ are suppressors of LipA induced innate immune responses. A mutation in any one of the xopN, xopQ, xopX or xopZ genes causes partial virulence deficiency while a xopN- xopX- double mutant exhibits a greater virulence deficiency. A xopN- xopQ- xopX- xopZ- quadruple mutant of X. oryzae pv. oryzae induces callose deposition, an innate immune response, similar to a X. oryzae pv. oryzae T3S- mutant in rice leaves. Overall, these results indicate that multiple T3S secreted proteins of X. oryzae pv. oryzae can suppress cell wall damage induced rice innate immune responses. PMID:24086651

Sinha, Dipanwita; Gupta, Mahesh Kumar; Patel, Hitendra Kumar; Ranjan, Ashish; Sonti, Ramesh V.

2013-01-01

300

Synthesis, structure and catechol-oxidase activity of copper(II) complexes of 17-hydroxy-16-( N-3-oxo-prop-1-enyl)amino steroids  

Microsoft Academic Search

Copper is next to iron the most important element in the biological transport, storage and in redox reactions of dioxygen. A bioanalogous activation of dioxygen with copper complexes is used for catalytical epoxidation, allylic hydroxylation and oxidative coupling of aromatic substrates, for example. With stereochemical information in form of chiral ligands, enantioselective reactions may be possible. Another aspect of interest

Rainer Wegner; Manuela Dubs; Helmar Görls; Christian Robl; Bruno Schönecker; Ernst-G Jäger

2002-01-01

301

Molecular structure and catechol oxidase activity of a new copper(I) complex with sterically crowded monodentate N-donor ligand  

Microsoft Academic Search

The attempted alkylation of 1,3-bis(2?-pyridylimino)isoindoline (indH) by the use of n-BuLi and subsequent alkyl halides led to quaternization of the pyridine nitrogens and the zwitterionic monodentate N-ligand (Me2ind)I was formed. By the use of the ligand the copper(I) complex [CuI(Me2ind)I2] was prepared and its structure determined. It was found to be good catalyst for the oxidation of 3,5-di-tert-butylcatechol (DTBCH2) to

Ádám Kupán; József Kaizer; Gábor Speier; Michel Giorgi; Marius Réglier; Ferenc Pollreisz

2009-01-01

302

Catechol oxidase activity of dinuclear copper(II) complexes of Robson type macrocyclic ligands: Syntheses, X-ray crystal structure, spectroscopic characterization of the adducts and kinetic studies  

Microsoft Academic Search

Five dinuclear copper(II) complexes, [Cu2L1(N3)2ˇ2H2O] (1), [Cu2L2(N3)2ˇ2H2O] (2), [Cu2L3(N3)2ˇ2H2O] (3), [Cu2L4(N3)2ˇ2H2O] (4) and [Cu2L5(N3)2ˇ2H2O] (5) of Robson type macrocyclic Schiff-base ligands derived from [2+2] condensation of 4-methyl-2,6-diformylphenol with 1,3-diaminopropane (H2L1), 1,2-diaminoethane (H2L2), 1,2-diaminopropane (H2L3), 1,2-diamino-2-methylpropane (H2L4) and 1,2-diaminocyclohexane (H2L5), respectively have been synthesized and characterized. Catecholase activity of those complexes using 3,5-di-tert-butylcatechol as substrate has been investigated in two solvents,

Kazi Sabnam Banu; Tanmay Chattopadhyay; Arpita Banerjee; Santanu Bhattacharya; Ennio Zangrando; Debasis Das

2009-01-01

303

Synthesis of new dinuclear dicopper(II) and dinickel(II) complexes. The kinetics of catechol oxidase and electrochemistry of a dicopper(II) complex  

Microsoft Academic Search

A new dinuclear ligand L', ethylene[OO'-bis-salicylidene-ß-diketone] bearing two symmetrical coordination sites was synthesized by the condensation of salicylaldehyde and acetylacetone, L, with 1,2-dibromoethane under reflux. The ligand L' in a 1:1 ratio was treated with CuCl2 and NiCl2 to yield the complexes, tetrachloro bis[OO'-bis- salicylidene-ß-diketone copper(II)] and bis[OO'-bis-salicylidene-ß-diketone nickel(II)] chloride. The complexes were subsequently characterized by spectroscopic techniques, elemental analysis,

Farukh Arjmand; Shamima Parveen; Sartaj Tabassum

2005-01-01

304

Comparative transcriptome profiling reveals different expression patterns in Xanthomonas oryzae pv. oryzae strains with putative virulence-relevant genes.  

PubMed

Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of rice bacterial blight, which is a major rice disease in tropical Asian countries. An attempt has been made to investigate gene expression patterns of three Xoo strains on the minimal medium XOM2, PXO99 (P6) and PXO86 (P2) from the Philippines, and GD1358 (C5) from China, which exhibited different virulence in 30 rice varieties, with putative virulence factors using deep sequencing. In total, 4,781 transcripts were identified in this study, and 1,151 and 3,076 genes were differentially expressed when P6 was compared with P2 and with C5, respectively. Our results indicated that Xoo strains from different regions exhibited distinctly different expression patterns of putative virulence-relevant genes. Interestingly, 40 and 44 genes involved in chemotaxis and motility exhibited higher transcript alterations in C5 compared with P6 and P2, respectively. Most other genes associated with virulence, including exopolysaccharide (EPS) synthesis, Hrp genes and type III effectors, including Xanthomonas outer protein (Xop) effectors and transcription activator-like (TAL) effectors, were down-regulated in C5 compared with P6 and P2. The data were confirmed by real-time quantitative RT-PCR, tests of bacterial motility, and enzyme activity analysis of EPS and xylanase. These results highlight the complexity of Xoo and offer new avenues for improving our understanding of Xoo-rice interactions and the evolution of Xoo virulence. PMID:23734193

Zhang, Fan; Du, Zhenglin; Huang, Liyu; Vera Cruz, Casiana; Zhou, Yongli; Li, Zhikang

2013-01-01

305

Comparative Transcriptome Profiling Reveals Different Expression Patterns in Xanthomonas oryzae pv. oryzae Strains with Putative Virulence-Relevant Genes  

PubMed Central

Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of rice bacterial blight, which is a major rice disease in tropical Asian countries. An attempt has been made to investigate gene expression patterns of three Xoo strains on the minimal medium XOM2, PXO99 (P6) and PXO86 (P2) from the Philippines, and GD1358 (C5) from China, which exhibited different virulence in 30 rice varieties, with putative virulence factors using deep sequencing. In total, 4,781 transcripts were identified in this study, and 1,151 and 3,076 genes were differentially expressed when P6 was compared with P2 and with C5, respectively. Our results indicated that Xoo strains from different regions exhibited distinctly different expression patterns of putative virulence-relevant genes. Interestingly, 40 and 44 genes involved in chemotaxis and motility exhibited higher transcript alterations in C5 compared with P6 and P2, respectively. Most other genes associated with virulence, including exopolysaccharide (EPS) synthesis, Hrp genes and type III effectors, including Xanthomonas outer protein (Xop) effectors and transcription activator-like (TAL) effectors, were down-regulated in C5 compared with P6 and P2. The data were confirmed by real-time quantitative RT-PCR, tests of bacterial motility, and enzyme activity analysis of EPS and xylanase. These results highlight the complexity of Xoo and offer new avenues for improving our understanding of Xoo-rice interactions and the evolution of Xoo virulence. PMID:23734193

Zhang, Fan; Du, Zhenglin; Huang, Liyu; Cruz, Casiana Vera; Zhou, Yongli; Li, Zhikang

2013-01-01

306

Xanthomonas oryzae pv. oryzae RpfE Regulates Virulence and Carbon Source Utilization without Change of the DSF Production  

PubMed Central

It has been known that most regulation of pathogenicity factor (rpf) genes in xanthomonads regulates virulence in response to the diffusible signal factor, DSF. Although many rpf genes have been functionally characterized, the function of rpfE is still unknown. We cloned the rpfE gene from a Xanthomonas oryzae pv. oryzae (Xoo) Korean race KACC10859 and generated mutant strains to elucidate the role of RpfE with respect to the rpf system. Through experiments using the rpfE-deficient mutant strain, we found that mutation in rpfE gene in Xoo reduced virulence, swarm motility, and production of virulence factors such as cellulase and extracellular polysaccharide. Disease progress by the rpfE-deficient mutant strain was significantly slowed compared to disease progress by the wild type and the number of the rpfE-deficient mutant strain was lower than that of the wild type in the early phase of infection in the inoculated rice leaf. The rpfE mutant strain was unable to utilize sucrose or xylose as carbon sources efficiently in culture. The mutation in rpfE, however, did not affect DSF synthesis. Our results suggest that the rpfE gene regulates the virulence of Xoo under different nutrient conditions without change of DSF production. PMID:25288965

Cho, Jung-Hee; Yoon, Joo-Mi; Lee, Sang-Won; Noh, Young-Hee; Cha, Jae-Soon

2013-01-01

307

NOVEL ORGANIZATION OF CATECHOL META PATHWAY GENES IN THE NITROBENZENE DEGRADER COMAMONAS SP. JS765 AND ITS EVOLUTIONARY IMPLICATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

The catechol meta cleavage pathway is one of the central metabolic pathways for the degradation of aromatic compounds. A novel organization of the pathway genes, different from that of classical soil microorganisms, has been observed in Sphingomonas sp HV3 and Pseudomonas sp. DJ77. In a Comamonas ...

308

Cloning of catechol 2,3-dioxygenase gene and construction of a stable genetically engineered strain for degrading crude oil.  

PubMed

Pseudomonas putida strain BNF1 was isolated to degrade aromatic hydrocarbons efficiently and use phenol as a main carbon and energy source to support its growth. Catechol 2,3-dioxygenase was found to be the responsible key enzyme for the biodegradation of aromatic hydrocarbons. Catechol 2,3-dioxygenase gene was cloned from plasmid DNA of P. putida strain BNF1. The nucleotide base sequence of a 924 bp segment encoding the catechol 2,3-dioxygenase (C23O) was determined. This segment showed an open reading frame, which encoded a polypeptide of 307 amino acids. C23O gene was inserted into NotI-cut transposon vector pUT/mini-Tn5 (Km(r)) to get a novel transposon vector pUT/mini-Tn5-C23O. With the helper plasmid PRK2013, the transposon vector pUT/mini-Tn5-C23O was introduced into one alkanes degrading strain Acinetobacter sp. BS3 by triparental conjugation, and then the C23O gene was integrated into the chromosome of Acinetobacter sp. BS3. And the recombinant BS3-C23O, which could express catechol 2,3-dioxygenase protein, was obtained. The recombinant BS3-C23O was able to degrade various aromatic hydrocarbons and n-alkanes. Broad substrate specificity, high enzyme activity, and the favorable stability suggest that the BS3-C23O was a potential candidate used for the biodegradation of crude oil. PMID:24426168

Xie, Yun; Yu, Feng; Wang, Qi; Gu, Xin; Chen, Wuling

2014-03-01

309

Iron transport-mediated antibacterial activity of and development of resistance to hydroxamate and catechol siderophore-carbacephalosporin conjugates.  

PubMed Central

Peptides containing residues of N5-acetyl-N5-hydroxy-L-ornithine were evaluated as potential artificial siderophores of beta-lactam-hypersusceptible Escherichia coli X580. Only those peptides which were capable of forming a hexadentate complex around ferric iron, which is analogous to the natural siderophore ferrichrome, were able to reverse the growth inhibition effects of the ferric iron chelator ethylenediamine di(o-hydroxyphenylacetic acid). A synthetic bis(catechol) spermidine derivative, similar to the natural siderophores enterobactin and agrobactin, also exhibited siderophore activity with this strain. Conjugation of the N5-acetyl-N5-hydroxy-L-ornithine tripeptide and the bis(catechol) siderophore to the potent carbacephalosporin loracarbef and closely related analogs provided compounds which exhibited antibacterial activity against E. coli X580. As was observed with the naturally occurring albomycins, the initial bactericidal effect was followed by the appearance of survivors that were resistant to the test compound. An enhanced killing effect was observed when the parent was incubated simultaneously with hydroxamate and catechol siderophore-antibiotic conjugates. Natural and synthetic siderophore growth promotion experiments with survivors resistant to the conjugates strongly suggested that disabled ferrichrome and enterobactin-catechol assimilation mechanisms may be responsible for the observed resistance. One isolated survivor was postulated to be a tonB mutant. The antibacterial activities of the described siderophore-carbacephalosporin conjugates appear to be related to an iron transport assimilation mechanism and would not have been detected during routine MIC testing procedures. PMID:1503447

Minnick, A A; McKee, J A; Dolence, E K; Miller, M J

1992-01-01

310

The catechol-O-methyl transferase (COMT) gene as a candidate for psychiatric phenotypes: evidence and lessons  

Microsoft Academic Search

The enzyme catechol-O-methyl transferase (COMT), identified in the 1950s, is involved in catabolism of monoamines that are influenced by psychotropic medications, including neuroleptics and antidepressants. The COMT gene lies in a chromosomal region of interest for psychosis and bipolar spectrum disorder and a common polymorphism within the gene alters the activity of the enzyme. As a consequence, COMT has been

N Craddock; M J Owen; M C O'Donovan

2006-01-01

311

Laccase immobilized on a PAN/adsorbents composite nanofibrous membrane for catechol treatment by a biocatalysis/adsorption process.  

PubMed

The treatment of catechol via biocatalysis and adsorption with a commercial laccase immobilized on polyacrylonitrile/montmorillonite/graphene oxide (PAN/MMT/GO) composite nanofibers was evaluated with a homemade nanofibrous membrane reactor. The properties in this process of the immobilized laccase on PAN, PAN/MMT as well as PAN/MMT/GO with different weight ratios of MMT and GO were investigated. These membranes were successfully applied for removal of catechol from an aqueous solution. Scanning electron microscope images revealed different morphologies of the enzyme aggregates on different supports. After incorporation of MMT or MMT/GO, the optimum pH showed an alkaline shift to 4, compared to 3.5 for laccase immobilized on pure PAN nanofibers. The optimum temperature was at 55 °C for all the immobilized enzymes. Besides, the addition of GO improved the operational stability and storage stability. A 39% ą 2.23% chemical oxygen demand (COD) removal from the catechol aqueous solution was achieved. Experimental results suggested that laccase, PAN, adsorbent nanoparticles (MMT/GO) can be combined together for catechol treatment in industrial applications. PMID:24651612

Wang, Qingqing; Cui, Jing; Li, Guohui; Zhang, Jinning; Li, Dawei; Huang, Fenglin; Wei, Qufu

2014-01-01

312

Cloning and mutagenesis of catechol 2,3-dioxygenase gene from the gram-positive Planococcus sp. strain S5.  

PubMed

In this study, the catechol 2,3-dioxygenase gene that encodes a 307- amino-acid protein was cloned from Planococcus sp. S5. The protein was identified to be a member of the superfamily I, subfamily 2A of extradiol dioxygenases. In order to study residues and regions affecting the enzyme's catalytic parameters, the c23o gene was randomly mutated by error-prone PCR. The wild-type enzyme and mutants containing substitutions within either the C-terminal or both domains were functionally produced in Escherichia coli and their activity towards catechol was characterized. The C23OB65 mutant with R296Q substitution showed significant tolerance to acidic pH with an optimum at pH 5.0. In addition, it showed activity more than 1.5 as high as that of the wild type enzyme and its Km was 2.5 times lower. It also showed altered sensitivity to substrate inhibition. The results indicate that residue at position 296 plays a role in determining pH dependence of the enzyme and its activity. Lower activity toward catechol was shown for mutants C23OB58 and C23OB81. Despite lower activity, these mutants showed higher affinity to catechol and were more sensitive to substrate concentration than nonmutated enzyme. PMID:23921803

Hupert-Kocurek, Katarzyna; Stawicka, Agnieszka; Wojcieszy?ska, Danuta; Guzik, Urszula

2013-01-01

313

Activity of a Carboxyl-Terminal Truncated Form of Catechol 2,3-Dioxygenase from Planococcus sp. S5  

PubMed Central

Catechol 2,3-dioxygenases (C23Os, E.C.1.13.12.2) are two domain enzymes that catalyze degradation of monoaromatic hydrocarbons. The catalytically active C-domain of all known C23Os comprises ferrous ion ligands as well as residues forming active site pocket. The aim of this work was to examine and discuss the effect of nonsense mutation at position 289 on the activity of catechol 2,3-dioxygenase from Planococcus strain. Although the mutant C23O showed the same optimal temperature for activity as the wild-type protein (35°C), it exhibited activity slightly more tolerant to alkaline pH. Mutant enzyme exhibited also higher affinity to catechol as a substrate. Its Km (66.17?ľM) was approximately 30% lower than that of wild-type enzyme. Interestingly, removal of the C-terminal residues resulted in 1.5- to 1.8-fold (P < 0.05) increase in the activity of C23OB61 against 4-methylcatechol and 4-chlorocatechol, respectively, while towards catechol the activity of the protein dropped to about 80% of that of the wild-type enzyme. The results obtained may facilitate the engineering of the C23O for application in the bioremediation of polluted areas. PMID:24693238

2014-01-01

314

VISCOSITY AND BINDER COMPOSITION EFFECTS ON TYROSINASE-BASED CARBON PASTE ELECTRODE FOR DETECTION OF PHENOL AND CATECHOL  

EPA Science Inventory

The systematic study of the effect of binder viscosity on the sensitivity of a tyrosinase-based carbon paste electrode (CPE) biosensor for phenol and catechol is reported. Silicon oil binders with similar (polydimethylsiloxane) chemical composition were used to represent a wid...

315

An Optical Biosensor based on Immobilization of Laccase and MBTH in Stacked Films for the Detection of Catechol  

PubMed Central

The fabrication of an optical biosensor by using stacked films where 3-methyl-2-benzothiazolinone hydrazone (MBTH) was immobilized in a hybrid nafion/sol-gel silicate film and laccase in a chitosan film for the detection of phenolic compounds was described. Quinone and/or phenoxy radical product from the enzymatic oxidation of phenolic compounds was allowed to couple with MBTH to form a colored azo-dye product for spectrophometric detection. The biosensor demonstrated a linear response to catechol concentration range of 0.5-8.0 mM with detection limit of 0.33 mM and response time of 10 min. The reproducibility of the fabricated biosensor was good with RSD value of 5.3 % (n = 8) and stable for at least 2 months. The use of the hybrid materials of nafion/sol-gel silicate to immobilize laccase has altered the selectivity of the enzyme to various phenolic compounds such as catechol, guaicol, o-cresol and m-cresol when compared to the non-immobilized enzyme. When immobilized in this hybrid film, the biosensor response only to catechol and not other phenolic compounds investigated. Immobilization in this hybrid material has enable the biosensor to be more selective to catechol compared with the non-immobilized enzyme. This shows that by a careful selection of different immobilization matrices, the selectivity of an enzyme can be modified to yield a biosensor with good selectivity towards certain targeted analytes.

Abdullah, Jaafar; Ahmad, Musa; Heng, Lee Yook; Karuppiah, Nadarajah; Sidek, Hamidah

2007-01-01

316

Density Functional Studies of a Heisenberg Spin Coupled Chromium-Semiquinone Complex and Its Chromium-Catechol  

E-print Network

Density Functional Studies of a Heisenberg Spin Coupled Chromium-Semiquinone Complex and Its Chromium-Catechol Analog Jorge H. Rodriguez,1 Daniel E. Wheeler, and James K. McCusker* Contribution from carried out which show net R and spin densities at the chromium ion and semiquinone, respectively. Some

McCusker, James K.

317

Crystal structures of human 108V and 108M catechol O-methyltransferase  

SciTech Connect

Catechol O-methyltransferase (COMT) plays important roles in the metabolism of catecholamine neurotransmitters and catechol estrogens. The development of COMT inhibitors for use in the treatment of Parkinson's disease has been aided by crystallographic structures of the rat enzyme. However, the human and rat proteins have significantly different substrate specificities. Additionally, human COMT contains a common valine-methionine polymorphism at position 108. The methionine protein is less stable than the valine polymorph, resulting in decreased enzyme activity and protein levels in vivo. Here we describe the crystal structures of the 108V and 108M variants of the soluble form of human COMT bound with S-adenosylmethionine (SAM) and a substrate analog, 3,5-dinitrocatechol. The polymorphic residue 108 is located in the {alpha}5-{beta}3 loop, buried in a hydrophobic pocket {approx}16 {angstrom} from the SAM-binding site. The 108V and 108M structures are very similar overall [RMSD of C{sup {alpha}} atoms between two structures (C{sup {alpha}} RMSD) = 0.2 {angstrom}], and the active-site residues are superposable, in accord with the observation that SAM stabilizes 108M COMT. However, the methionine side chain is packed more tightly within the polymorphic site and, consequently, interacts more closely with residues A22 ({alpha}2) and R78 ({alpha}4) than does valine. These interactions of the larger methionine result in a 0.7-{angstrom} displacement in the backbone structure near residue 108, which propagates along {alpha}1 and {alpha}5 toward the SAM-binding site. Although the overall secondary structures of the human and rat proteins are very similar (C{sup {alpha}} RMSD = 0.4 {angstrom}), several nonconserved residues are present in the SAM-(I89M, I91M, C95Y) and catechol- (C173V, R201M, E202K) binding sites. The human protein also contains three additional solvent-exposed cysteine residues (C95, C173, C188) that may contribute to intermolecular disulfide bond formation and protein aggregation.

Rutherford, K.; Le Trong, I.; Stenkamp, R.E.; Parson, W.W. (UWASH)

2008-08-01

318

Neuronal effects of 4-t-Butylcatechol: A model for catechol-containing antioxidants  

SciTech Connect

Many herbal medicines and dietary supplements sold as aids to improve memory or treat neurodegenerative diseases or have other favorable effects on the CNS contain a catechol or similar 1,2-dihydroxy aromatic moiety in their structure. As an approach to isolate and examine the neuroprotective properties of catechols, a simple catechol 4-t-Butylcatechol (TBC) has been used as a model. In this study, we investigated the effects of TBC on lipopolysaccharide (LPS)-activated microglial-induced neurotoxicity by using the in vitro model of coculture murine microglial-like cell line HAPI with the neuronal-like human neuroblastoma cell line SH-SY5Y. We also examined the effects of TBC on 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in human dopaminergic neuroblastoma SH-SY5Y cells. TBC at concentrations from 0.1-10 {mu}M had no toxic effect on HAPI cells and SH-SY5Y cells, and it inhibited LPS (100 ng/ml)-induced increases of superoxide, intracellular ROS, gp91{sup Phox}, iNOS and a decrease of HO-1 in HAPI cells. Under coculture condition, TBC significantly reduced LPS-activated microglia-induced dopaminergic SH-SY5Y cells death. Moreover, TBC (0.1-10 {mu}M) inhibited 6-OHDA-induced increases of intracellular ROS, iNOS, nNOS, and a decrease of mitochondria membrane potential, and cell death in SH-SY5Y cells. However, the neurotoxic effects of TBC (100 {mu}M) on SH-SY5Y cells were also observed including the decrease in mitochondria membrane potential and the increase in COX-2 expression and cell death. TBC-induced SH-SY5Y cell death was attenuated by pretreatment with NS-398, a selective COX-2 inhibitor. In conclusion, this study suggests that TBC might possess protective effects on inflammation- and oxidative stress-related neurodegenerative disorders. However, the high concentration of TBC might be toxic, at least in part, for increasing COX-2 expression.

Lo, Y.-C. [Department of Pharmacology and Graduate Institute of Pharmacology, Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China)], E-mail: yichlo@kmu.edu.tw; Liu Yuxin [Neuropharmacology Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709 (United States); Lin, Y.-C.; Shih, Y.-T.; Liu, C.-M. [Department of Pharmacology and Graduate Institute of Pharmacology, Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China); Burka, Leo T. [Chemistry Section, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709 (United States)

2008-04-15

319

Antiplatelet Effect of Catechol Is Related to Inhibition of Cyclooxygenase, Reactive Oxygen Species, ERK/p38 Signaling and Thromboxane A2 Production  

PubMed Central

Catechol (benzenediol) is present in plant-derived products, such as vegetables, fruits, coffee, tea, wine, areca nut and cigarette smoke. Because platelet dysfunction is a risk factor of cardiovascular diseases, including stroke, atherosclerosis and myocardial infarction, the purpose of this study was to evaluate the anti-platelet and anti-inflammatory effect of catechol and its mechanisms. The effects of catechol on cyclooxygenase (COX) activity, arachidonic acid (AA)-induced aggregation, thromboxane B2 (TXB2) production, lactate dehydrogenase (LDH) release, reactive oxygen species (ROS) production and extracellular signal-regulated kinase (ERK)/p38 phosphorylation were determined in rabbit platelets. In addition, its effect on IL-1?-induced prostaglandin E2 (PGE2) production by fibroblasts was determined. The ex vivo effect of catechol on platelet aggregation was also measured. Catechol (5-25 ľM) suppressed AA-induced platelet aggregation and inhibited TXB2 production at concentrations of 0.5–5 ľM; however, it showed little cytotoxicity and did not alter U46619-induced platelet aggregation. Catechol (10–50 ľM) suppressed COX-1 activity by 29–44% and COX-2 activity by 29–50%. It also inhibited IL-1?-induced PGE2 production, but not COX-2 expression of fibroblasts. Moreover, catechol (1–10 ľM) attenuated AA-induced ROS production in platelets and phorbol myristate acetate (PMA)-induced ROS production in human polymorphonuclear leukocytes. Exposure of platelets to catechol decreased AA-induced ERK and p38 phosphorylation. Finally, intravenous administration of catechol (2.5–5 ľmole/mouse) attenuated ex vivo AA-induced platelet aggregation. These results suggest that catechol exhibited anti-platelet and anti-inflammatory effects, which were mediated by inhibition of COX, ROS and TXA2 production as well as ERK/p38 phosphorylation. The anti-platelet effect of catechol was confirmed by ex vivo analysis. Exposure to catechol may affect platelet function and thus cardiovascular health. PMID:25122505

Wang, Tong-Mei; Lin, Bor-Ru; Yeung, Sin-Yuet; Yeh, Chien-Yang; Cheng, Ru-Hsiu; Jeng, Jiiang-Huei

2014-01-01

320

Cyanobacteria-mediated phenylpropanoids and phytohormones in rice ( Oryza sativa ) enhance plant growth and stress tolerance  

Microsoft Academic Search

Phenylpropanoids, flavonoids and plant growth regulators in rice (Oryza sativa) variety (UPR 1823) inoculated with different cyanobacterial strains namely Anabaena oryzae, Anabaena doliolum, Phormidium fragile, Calothrix geitonos, Hapalosiphon intricatus, Aulosira fertilissima,\\u000a Tolypothrix tenuis, Oscillatoria acuta and Plectonema boryanum were quantified using HPLC in pot conditions after 15 and 30 days. Qualitative analysis of the induced compounds using reverse\\u000a phase HPLC and

Dhananjaya P. Singh; Ratna Prabha; Mahesh S. Yandigeri; Dilip K. Arora

321

The isolation and characterization of plastid DNA from rice (Oryza sativa)  

E-print Network

THE ISOLATION AND CHARACTERIZATION OF PLASTID DNA FROM RICE (ORYZA SATIVA) A Thesis by CHANTEL FOUGERON SCHEURING Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE May 1987 Major Subject: Genetics THE ISOLATION AND CHARACTERIZATION OF PLASTID DNA FROM RICE (ORYZA SATIVA) by ~L FOUGERON SCHEURING Approved as to style and content by: a' (Chairman) C J. C ghton Miller, Jr. David O. Peterson (Member...

Scheuring, Chantel Fougeron

2012-06-07

322

L (+) Lactate production from carbohydrates and lignocellulosic materials by Rhizopus oryzae UMIP 4.77  

Microsoft Academic Search

The lactate excretion by Rhizopus oryzae on various carbohydrates was studied in order to assess the potential of lactate production from raw materials. Six collection\\u000a strains were tested on ten commercial carbohydrates i.e. glucose, xylose, glycerol, sucrose, lactose, cellobiose, inulin,\\u000a starch, cellulose and fructose in flask or stirred-tank bioreactor. On glucose and xylose, lactate was produced by R. oryzae UMIP

Guerrick Vially; Rémy Marchal; Nathalie Guilbert

2010-01-01

323

Monoolein production by triglycerides hydrolysis using immobilized Rhizopus oryzae lipase.  

PubMed

Lipase extracted from Rhizopus oryzae was immobilized in alginate gel beads. The effects of the immobilization conditions, such as, alginate concentration, CaCl2 concentration and amount of initial enzyme on retained activity (specific activity ratio of entrapped active lipase to free lipase) were investigated. The optimal conditions for lipase entrapment were determined: 2% (w/v) alginate concentration, 100mM CaCl2 and enzyme ratio of 2000IU/mL.In such conditions, immobilized lipase by inclusion in alginate showed a highest stability and activity, on olive oil hydrolysis reaction where it could be reused for 10 cycles. After 15min of hydrolysis reaction, the mass composition of monoolein, diolein and triolein were about 78%, 10% and 12%. Hydrolysis' products purification by column chromatography lead to a successful separation of reaction compounds and provide a pure fraction of monoolein which is considered as the widest used emulsifier in food and pharmaceutical industries. PMID:24755261

Ghattas, Nesrine; Abidi, Ferid; Galai, Said; Marzouki, M Nejib; Salah, Abderraouf Ben

2014-07-01

324

Activation of polyphenol oxidase by polyamines.  

PubMed

Latent polyphenol oxidase was extracted and partially purified from grape cell suspension cultures. The enzyme was shown to be activated by polyamines. Activation of the enzyme increased with increasing polyamine concentrations and half-maximal activation was in the order of 8mM. Kinetic parameters, Km and Vm, were also calculated for the latent and activated enzymes. The activating effect of polyamines was studied at different pH values. Optimum pH was 4.5 for latent and activated enzymes. However, the highest degree of activation was obtained at pH 5. Activation caused a higher sensitivity of polyphenol oxidase to pH and temperature. The ability of polyamines to activate the enzyme may suggest a limited conformational change. PMID:1804105

Jiménez-Atiénzar, M; Angeles Pedreńo, M; García-Carmona, F

1991-12-01

325

Natural Compounds as Modulators of NADPH Oxidases  

PubMed Central

Reactive oxygen species (ROS) are cellular signals generated ubiquitously by all mammalian cells, but their relative unbalance triggers also diseases through intracellular damage to DNA, RNA, proteins, and lipids. NADPH oxidases (NOX) are the only known enzyme family with the sole function to produce ROS. The NOX physiological functions concern host defence, cellular signaling, regulation of gene expression, and cell differentiation. On the other hand, increased NOX activity contributes to a wide range of pathological processes, including cardiovascular diseases, neurodegeneration, organ failure, and cancer. Therefore targeting these enzymatic ROS sources by natural compounds, without affecting the physiological redox state, may be an important tool. This review summarizes the current state of knowledge of the role of NOX enzymes in physiology and pathology and provides an overview of the currently available NADPH oxidase inhibitors derived from natural extracts such as polyphenols. PMID:24381714

2013-01-01

326

Cation transport in cytochrome oxidase reconstituted vesicles.  

PubMed

Cation translocation across the membrane of cytochrome oxidase reconstituted vesicles may be followed with a simple spectrophotometric method. Cytochrome oxidase reconstituted vesicles, supplemented with ascorbate and cytochrome c. induce large spectral changes of the positive dye safranine, reversed by uncouplers and inhibitors of respiration. The dye is probably accumulated in the inner space of the vesicles, where it reaches high concentrations and aggregates. The spectral shifts and the absorbance changes, due to aggregation, are proportional to the amount of the dye taken up and depend on the respiratory control. In the presence of potassium, valinomycin causes an inhibition, whereas nigericin stimulates the dye uptake. The data are discussed in terms of electrical potential dependent fluxes. PMID:13827

Gutweniger, H; Massari, S; Beltrame, M; Colonna, R

1977-02-01

327

Defensive Roles of Polyphenol Oxidase in Plants  

Microsoft Academic Search

Plant polyphenol oxidases (PPOs) are widely distributed and well-studied oxidative enzymes, and their effects on discoloration in damaged and diseased plant tissues have been known for many years. The discovery in C.A. Ryan's laboratory in the mid-1990s that tomato PPO is induced by the herbivore defense signals systemin and jasmonate, together with seminal work on PPO's possible effects on herbiv-

C. Peter Constabel; Raymond Barbehenn

328

Sulfhydryl oxidases: sources, properties, production and applications  

Microsoft Academic Search

The formation of disulfide bonds in proteins and small molecules can greatly affect their functionality. Sulfhydryl oxidases\\u000a (SOXs) are enzymes capable of oxidising the free sulfhydryl groups in proteins and thiol-containing small molecules by using\\u000a molecular oxygen as an electron acceptor. SOXs have been isolated from the intracellular compartments of many organisms, but\\u000a also secreted SOXs are known. These latter

Greta Faccio; Outi Nivala; Kristiina Kruus; Johanna Buchert; Markku Saloheimo

2011-01-01

329

Silicon-Mediated Inactivation of Diamine Oxidase  

Microsoft Academic Search

The design, synthesis, and biologic evaluation of potential silicon-containing inhibitors of diamine oxidases (siladiaminopropane1, silaputrescine2, and sila analogs of cadaverine3, 4,and5) are described. All compounds have been prepared independently. The common feature in the reported syntheses is the way chosen to introduce the amine group relative to silicon: the Gabriel-type approach to obtaining aminomethyl- and aminopropylsilanes and the Mitsunobu-type approach

V. Van Dorsselaer; D. Schirlin; P. Marchal; F. Weber; C. Danzin

1996-01-01

330

Ligand interactions with galactose oxidase: mechanistic insights.  

PubMed Central

Interactions between galactose oxidase and small molecules have been explored using a combination of optical absorption, circular dichroism, and electron paramagnetic resonance (EPR) spectroscopies to detect complex formation and characterize the products. Anions bind directly to the cupric center in both active and inactive galactose oxidase, converting to complexes with optical and EPR spectra that are distinctly different from those of the starting aquo enzyme. Azide binding is coupled to stoichiometric proton uptake by the enzyme, reflecting the generation of a strong base (pKa > 9) in the active site anion adduct. At low temperature, the aquo enzyme converts to a form that exhibits the characteristic optical and EPR spectra of an anion complex, apparently reflecting deprotonation of the coordinated water. Anion binding results in a loss of the optical transition arising from coordinated tyrosine, implying displacement of the axial tyrosine ligand on forming the adduct. Nitric oxide binds to galactose oxidase, forming a specific complex exhibiting an unusual EPR spectrum with all g values below 2. The absence of Cu splitting in this spectrum and the observation that the cupric EPR signal from the active site metal ion is not significantly decreased in the complex suggest a nonmetal interaction site for NO in galactose oxidase. These results have been interpreted in terms of a mechanistic scheme where substrate binding displaces a tyrosinate ligand from the active site cupric ion, generating a base that may serve to deprotonate the coordinated hydroxyl group of the substrate, activating it for oxidation. The protein-NO interactions may probe a nonmetal O2 binding site in this enzyme. PMID:8386015

Whittaker, M M; Whittaker, J W

1993-01-01

331

Characterization of polyphenol oxidase in coffee  

Microsoft Academic Search

Polyphenol oxidase (PPO) was characterized in partially purified extracts of leaves (PPO-L) and fruit endosperm (PPO-E) of coffee (Coffea arabica L.). PPO activity was higher in early developmental stages of both leaves and endosperm of fruits. Wounding or exposure of coffee leaves to methyl jasmonate increased PPO activity 1.5–4-fold. PPO was not latent and was not activated by protease treatment.

Paulo Mazzafera; Simon P Robinson

2000-01-01

332

Imaging Monoamine Oxidase in the Human Brain  

SciTech Connect

Positron emission tomography (PET) studies mapping monoamine oxidase in the human brain have been used to measure the turnover rate for MAO B; to determine the minimum effective dose of a new MAO inhibitor drug lazabemide and to document MAO inhibition by cigarette smoke. These studies illustrate the power of PET and radiotracer chemistry to measure normal biochemical processes and to provide information on the effect of drug exposure on specific molecular targets.

Fowler, J. S.; Volkow, N. D.; Wang, G-J.; Logan, Jean

1999-11-10

333

A comparative study on the degradation of gallic acid by Aspergillus oryzae and Phanerochaete chrysosporium.  

PubMed

Recently, as an emerging persistent dissolved organic pollutant (DOP), gallic acid (GA) and its efficient decomposition methods have received global attention. The present work aimed to compare the effect of Aspergillus oryzae 5992 and Phanerochaete chrysosporium 40719 on degradation of different concentrations of GA. The A. oryzae grew well and achieved a GA removal rate up to 99% in media containing 1-4% GA, much higher than P. chrysosporium. The activity of laccase and lignin peroxidase excreted by A. oryzae was higher than that by P. chrysosporium in the presence of GA. Based on the results of high-performance liquid chromatography-electrospray ionization-mass spectrometry, three relevant intermediate metabolites were determined as progallin A, methyl gallate, and pyrogallic acid, implying that A. oryzae could not degrade GA unless the carboxyl in the molecule was protected or removed. In view of the ability of A. oryzae to accommodate a high concentration of GA and achieve a high removal rate, as well as the significantly different enzyme activities involved in GA degradation and the underlying mechanisms between the two fungal strains, A. oryzae is proven to be a superior strain for the degradation of DOP. PMID:25026596

Guo, Danzhao; Zhang, Zhicai; Liu, Dan; Zheng, Huihua; Chen, Hui; Chen, Keping

2014-01-01

334

Random Mutagenesis of the Aspergillus oryzae Genome Results in Fungal Antibacterial Activity  

PubMed Central

Multidrug-resistant bacteria cause severe infections in hospitals and communities. Development of new drugs to combat resistant microorganisms is needed. Natural products of microbial origin are the source of most currently available antibiotics. We hypothesized that random mutagenesis of Aspergillus oryzae would result in secretion of antibacterial compounds. To address this hypothesis, we developed a screen to identify individual A. oryzae mutants that inhibit the growth of Methicillin-resistant Staphylococcus aureus (MRSA) in vitro. To randomly generate A. oryzae mutant strains, spores were treated with ethyl methanesulfonate (EMS). Over 3000 EMS-treated A. oryzae cultures were tested in the screen, and one isolate, CAL220, exhibited altered morphology and antibacterial activity. Culture supernatant from this isolate showed antibacterial activity against Methicillin-sensitive Staphylococcus aureus, MRSA, and Pseudomonas aeruginosa, but not Klebsiella pneumonia or Proteus vulgaris. The results of this study support our hypothesis and suggest that the screen used is sufficient and appropriate to detect secreted antibacterial fungal compounds resulting from mutagenesis of A. oryzae. Because the genome of A. oryzae has been sequenced and systems are available for genetic transformation of this organism, targeted as well as random mutations may be introduced to facilitate the discovery of novel antibacterial compounds using this system. PMID:23983696

Leonard, Cory A.; Brown, Stacy D.; Hayman, J. Russell

2013-01-01

335

Development of INDEL markers to discriminate all genome types rapidly in the genus Oryza  

PubMed Central

The wild Oryza species are rich in genetic diversity and are good resources for modern breeding of rice varieties. The reliable ex situ conservation of various genetic resources supports both basic and applied rice research. For this purpose, we developed PCR-based and co-dominant insertion/deletion (INDEL) markers which enable the discrimination of the genome types or species in the genus Oryza. First, 12,107 INDEL candidate sequences were found in the BAC end sequences for 12 Oryza species available in public databases. Next, we designed PCR primers for INDEL-flanking sequences to match the characteristics of each INDEL, based on an assessment of their likelihood to give rise to a single or few PCR products in all 102 wild accessions, covering most Oryza genome types. Then, we selected 22 INDEL markers to discriminate all genome types in the genus Oryza. A phylogenetic tree of 102 wild accessions and two cultivars according to amplicon polymorphisms for the 22 INDEL markers corresponded well to those in previous studies, indicating that the INDEL markers developed in this study were a useful tool to improve the reliability of identification of wild Oryza species in the germplasm stocks. PMID:24273419

Yamaki, Shinichiro; Ohyanagi, Hajime; Yamasaki, Masanori; Eiguchi, Mitsugu; Miyabayashi, Toshie; Kubo, Takahiko; Kurata, Nori; Nonomura, Ken-Ichi

2013-01-01

336

Dihydroxynitrobenzaldehydes and hydroxymethoxynitrobenzaldehydes: synthesis and biological activity as catechol-O-methyltransferase inhibitors.  

PubMed

A series of nitro derivatives of dihydroxy- and hydroxymethoxybenzaldehyde was synthesized and tested as potential inhibitors of partially purified pig liver catechol-O-methyltransferase (COMT). All the dihydroxynitrobenzaldehydes prepared were potent inhibitors of COMT, but only one hydroxymethoxynitrobenzaldehyde (3-hydroxy-4-methoxy-5-nitrobenzaldehyde) showed activity as a COMT inhibitor. Although previously reported data showed that the presence of electron-withdrawing substituents at position 5 seemed to be very important for activity as COMT inhibitor, our results suggest that the requirement necessary to enhance the activity of the dihydroxyni-trobenzaldehyde derivatives toward COMT is the presence of the nitro group in a position ortho with respect to one hydroxyl group. The assayed compounds showed a reversible inhibition of COMT, which was mixed for all the dihydroxynitro derivatives but noncompetitive for 3-hydroxy-4-methoxy-5-nitrobenzaldehyde when pyrocatechol was the variable substrate and uncompetitive in all the inhibitors with respect to S-adenosyl-L-methionine. PMID:1469689

Pérez, R A; Fernández-Alvarez, E; Nieto, O; Piedrafita, F J

1992-11-27

337

In vivo assessment of catechol O-methyltransferase activity in rabbit skeletal muscle.  

PubMed

With the use of microdialysis technique in the anesthetized rabbit, we examined the catechol O-methyltransferase (COMT) activity at the skeletal muscle interstitium. We implanted a dialysis probe into the adductor muscle, and monitored dialysate catecholamines and their metabolites with chromatogram-electrochemical detection. Administration of COMT inhibitor (entacapone) decreased dialysate 3-methoxy 4-hydroxyphenylglycol (MHPG) levels. Local administration of dihydroxyphenylglycol induced increases in dialysate MHPG levels. These increases in dialysate MHPG levels were suppressed by the addition of entacapone. The concentration of MHPG in the skeletal muscle dialysate corresponded to the COMT activity in the skeletal muscle. Furthermore, local administration of norepinephrine or epinephrine increased normetanephrine or metanephrine levels in dialysate but not MHPG levels. Skeletal muscle microdialysis with local administration of catecholamine offers a new method for in vivo assessment of regional COMT activity. PMID:15182744

Fujii, Takafumi; Yamazaki, Toji; Akiyama, Tsuyoshi; Sano, Shunji; Mori, Hidezo

2004-04-30

338

The catechol-O-methyltransferase gene (COMT) and cognitive function from childhood through adolescence  

PubMed Central

Genetic variation in the catechol-O-methyltransferase gene (COMT) can influence cognitive function, and this effect may depend on developmental stage. Using a large representative British birth cohort, we investigated the effect of COMT on cognitive function (verbal and non-verbal) at ages 8 and 15 years taking into account the possible modifying effect of pubertal stage. Five functional COMT polymorphisms, rs6269, rs4818, rs4680, rs737865 and rs165599 were analysed. Associations between COMT polymorphisms and cognition were tested using regression and latent variable structural equation modelling (SEM). Before correction for multiple testing, COMT rs737865 showed association with reading comprehension, verbal ability and global cognition at age 15 years in pubescent boys only. Although there was some evidence for age- and sex-specific effects of the COMT rs737865 none remained significant after correction for multiple testing. Further studies are necessary in order to make firmer conclusions. PMID:23178897

Gaysina, Darya; Xu, Man K.; Barnett, Jennifer H.; Croudace, Tim J.; Wong, Andrew; Richards, Marcus; Jones, Peter B.

2013-01-01

339

[Cloning and sequencing of ACC oxidase gene from sugarcane].  

PubMed

The plant hormone ethylene is not only responsible for the initiation of fruit ripening, senescence and dormancy but also for regulating many other plant developmental processes, such as seed germination, root initiation, growth, floral differentiation, sex differentiation and responding to environment stresses. One of the rate-limiting steps for ethylene biosynthesizing in plant is catalyzed by 1-aminocyclopropane-1-carboxylate (ACC) oxidase. Understanding of ethylene expressive pattern in plant is an entrance to understand the roles of ethylene on plant. In this paper, two degenerate oligonucleotide primers were designed, coding for two conservative amino acid regions in ACC oxidase protein family, the sequences of the two primers were TAGAGCTCGATGC[TA]TG [CT]GA[GA]AA[AC]TGGGG and CGTCTAGAGCTTC[GA]AATCTTGGCTCCTT respectively. A PCR amplification was performed on sugarcane (Saccharum L. Hybrid cv. ROC16) DNA template, and produced a fragment of 940 bp. By using the program of BLAST on NCBI GenBank database, the sequence presented a very high match with the ACC oxidase genes from other plants, 63 searched out sequences were all ACC oxidase genes. After alignment on PCgene program, the identities of the cloned fragment with ACC oxidase genes from rice and bamboo were both reaching about 88%. So we can concluded that the cloned sequence was a member of ACC oxidase genes fragment from sugarcane. The sequence has been submitted to the GenBank database, the accession number is AF442821. According to the ACC oxidase protein family, a 'intron' of 103 bp was excluded and the sequence coded 279 amino acids, which spanned 88% of the putative whole sequence in length. Alignment and phylogenetic analysis of the amino acid sequence deduced from this fragment and the ACC oxidase sequences of other plants retrieved from GenBank were carried out by using PCgene program. The putative amino acid sequence shared a homology of 86% with the ACC oxidases of bamboo and rice, 74.6% with banana, 70% with tomato and potato and 68% with melon and carnation, which showed that the homology of sugarcane ACC oxidase with monocot was higher than with dicot. The results of phylogenetic analysis showed that ACC oxidase from sugarcane and ACC oxidases from rice clustered together firstly, and then came those from banana, ACC oxidases of dicot from potato, tomato, petunia, melon, Arabidopsis thaliana and carnation came subsequently. It indicated that sugarcane ACC oxidase had a closer phylogenetic affinities to the monocot ACC oxidase sequences than to the dicot ACC oxidases sequences. The clustering results of ACC oxidase molecules accorded with morphological classification system. PMID:12812078

Wang, Zi-Zhang; Li, Yang-Rui; Zhang, Shu-Zhen; Lin, Jun-Fang; Guo, Li-Qiong

2003-01-01

340

Various applications of immobilized glucose oxidase and polyphenol oxidase in a conducting polymer matrix.  

PubMed

In this study, glucose oxidase and polyphenol oxidase were immobilized in conducting polymer matrices; polypyrrole and poly(N-(4-(3-thienyl methylene)-oxycarbonyl phenyl) maleimide-co-pyrrole) via electrochemical method. Fourier transform infrared and scanning electron microscope were employed to characterize the copolymer of (N-(4-(3-thienyl methylene)-oxycarbonyl phenyl) maleimide) with pyrrole. Kinetic parameters, maximum reaction rate and Michealis-Menten constant, were determined. Effects of temperature and pH were examined for immobilized enzymes. Also, storage and operational stabilities of enzyme electrodes were investigated. Glucose and polyphenol oxidase enzyme electrodes were used for determination of the glucose amount in orange juices and human serum and phenolic amount in red wines, respectively. PMID:17291580

Cil, M; Böyükbayram, A E; Kiralp, S; Toppare, L; Ya?ci, Y

2007-06-01

341

Expression of colSR Genes Increased in the rpf Mutants of Xanthomonas oryzae pv. oryzae KACC10859  

PubMed Central

The rpf genes and colSXOO1207/colRXOO1208 were known to require for virulence of Xanthomonas oryzae pv. oryzae (Xoo). In Xoo KACC10331 genome, two more colS/colR genes, colSXOO3534 (raxH)/colRXOO3535 (raxR) and colSXOO3762/colRXOO3763 were annotated. The colSXOO3534/colRXOO3535 were known to control AvrXa21 activity and functions of colSXOO3762/colRXOO3763 were unknown in Xoo. To characterize the relationship between rpf and colS/colR genes, expression of colS/colR genes in Rpf mutants of Xoo were analyzed with quantitative reverse transcription PCR (qRT-PCR). Expressions of all three colS/colR genes increased in the rpfF mutant in which DSF synthesis is defective. Expression of colSXOO1207/colRXOO1208, colSXOO3534/colRXOO3535 and colSXOO3762/colRXOO3763 increased 2, 2–7, 3–13 folds respectively. Expression of colSXOO3534 and colSXOO3762 also increased 2–4 folds in the rpfG mutant in which the signal from DSF is no longer transferred to down-stream. Expression of the other colS/colR genes was not significantly changed in the rpfG mutant compared to the wild type. Since RpfF and RpfG are responsible for DSF synthesis and signal transfer from DSF to down-stream to regulate virulence gene expression, these results suggest that the DSF and DSF-mediated signal regulate negatively three colS/colR genes in Xoo. PMID:25289017

Noh, Young-Hee; Kim, Sun-Young; Han, Jong-Woo; Seo, Young-Su; Cha, Jae-Soon

2014-01-01

342

A Novel Manganese Efflux System, YebN, Is Required for Virulence by Xanthomonas oryzae pv. oryzae  

PubMed Central

Manganese ions (Mn2+) play a crucial role in virulence and protection against oxidative stress in bacterial pathogens. Such pathogens appear to have evolved complex mechanisms for regulating Mn2+ uptake and efflux. Despite numerous studies on Mn2+ uptake, however, only one efflux system has been identified to date. Here, we report on a novel Mn2+ export system, YebN, in Xanthomonas oryzae pv. oryzae (Xoo), the causative agent of bacterial leaf blight. Compared with wild-type PXO99, the yebN mutant was highly sensitive to Mn2+ and accumulated high concentrations of intracellular manganese. In addition, we found that expression of yebN was positively regulated by Mn2+ and the Mn2+-dependent transcription regulator, MntR. Interestingly, the yebN mutant was more tolerant to methyl viologen and H2O2 in low Mn2+ medium than PXO99, but more sensitive in high Mn2+ medium, implying that YebN plays an important role in Mn2+ homoeostasis and detoxification of reactive oxygen species (ROS). Notably, deletion of yebN rendered Xoo sensitive to hypo-osmotic shock, suggesting that YebN may protect against such stress. That mutation of yebN substantially reduced the Xoo growth rate and lesion formation in rice implies that YebN could be involved in Xoo fitness in host. Although YebN has two DUF204 domains, it lacks homology to any known metal transporter. Hence, this is the first report of a novel metal export system that plays essential roles in hypo-osmotic and oxidative stress, and virulence. Our results lay the foundations for elucidating the complex and fascinating relationship between metal homeostasis and host-pathogen interactions. PMID:21789199

Li, Chunxia; Tao, Jun; Mao, Daqing; He, Chaozu

2011-01-01

343

Alternative sigma factor RpoN2 is required for flagellar motility and full virulence of Xanthomonas oryzae pv. oryzae.  

PubMed

Xanthomonas oryzae pv. oryzae (Xoo), the bacterial blight pathogen of rice, harbors a single polar flagellum for motility. How the flagellar system is regulated and how it is related to bacterial pathogenesis are not well understood. The genomic sequence of Xoo strain PXO99(A) revealed a flagellar regulon containing over 60 contiguous genes. A gene encoding alternative sigma factor 54 (?(54)), named as rpoN2, is located in the central region of the regulon. RT-PCR analysis demonstrated rpoN2 was transcribed in an operon with flgRR, and fleQ. Single gene deletion mutants of the rpoN2 operon were generated. The rpoN2 and fleQ mutant lost swimming motility, whereas the flgRR mutant remained motile. Quantitative RT-PCR analysis further demonstrated that expression of regulatory genes fliA and flgM, and structural genes flgG, flhB, and fliC were significantly down-regulated in the rpoN2 and fleQ mutants. These results indicated that RpoN2 and FleQ synergistically controlled flagellar motility by regulating gene expression. Interestingly, the rpoN2 mutant, but not the fleQ mutant was impaired in its virulence on rice. In addition, we showed that the flagellin gene fliC mutant, which was non-motile, was not defective in virulence. Thus, we concluded that flagellar motility might not be essential for Xoo virulence in rice, and RpoN2 probably regulated bacterial virulence through a manner independent of its role in controlling flagellar gene expression. PMID:25126992

Tian, Fang; Yu, Chao; Li, Haiyun; Wu, Xiaoli; Li, Bo; Chen, Huamin; Wu, Maosen; He, Chenyang

2015-01-01

344

Metabolomic and transcriptomic analysis of the rice response to the bacterial blight pathogen Xanthomonas oryzae pv. oryzae  

PubMed Central

Bacterial leaf blight (BLB), caused by Xanthomonas oryzae pv. oryzae (Xoo), gives rise to devastating crop losses in rice. Disease resistant rice cultivars are the most economical way to combat the disease. The TP309 cultivar is susceptible to infection by Xoo strain PXO99. A transgenic variety, TP309_Xa21, expresses the pattern recognition receptor Xa21, and is resistant. PXO99?raxST, a strain lacking the raxST gene, is able to overcome Xa21-mediated immunity. We used a single extraction solvent to demonstrate comprehensive metabolomics and transcriptomics profiling under sample limited conditions, and analyze the molecular responses of two rice lines challenged with either PXO99 or PXO99?raxST. LC–TOF raw data file filtering resulted in better within group reproducibility of replicate samples for statistical analyses. Accurate mass match compound identification with molecular formula generation (MFG) ranking of 355 masses was achieved with the METLIN database. GC–TOF analysis yielded an additional 441 compounds after BinBase database processing, of which 154 were structurally identified by retention index/MS library matching. Multivariate statistics revealed that the susceptible and resistant genotypes possess distinct profiles. Although few mRNA and metabolite differences were detected in PXO99 challenged TP309 compared to mock, many differential changes occurred in the Xa21-mediated response to PXO99 and PXO99?raxST. Acetophenone, xanthophylls, fatty acids, alkaloids, glutathione, carbohydrate and lipid biosynthetic pathways were affected. Significant transcriptional induction of several pathogenesis related genes in Xa21 challenged strains, as well as differential changes to GAD, PAL, ICL1 and Glutathione-S-transferase transcripts indicated limited correlation with metabolite changes under single time point global profiling conditions. Electronic supplementary material The online version of this article (doi:10.1007/s11306-010-0218-7) contains supplementary material, which is available to authorized users. PMID:20676379

Fischer, Steve; Wohlgemuth, Gert; Katrekar, Anjali; Jung, Ki-hong; Ronald, Pam C.

2010-01-01

345

The conformational state of polyphenol oxidase from field bean (Dolichos lablab) upon SDS and acid-pH activation  

PubMed Central

Field bean (Dolichos lablab) contains a single isoform of PPO (polyphenol oxidase) – a type III copper protein that catalyses the o-hydroxylation of monophenols and oxidation of o-diphenols using molecular oxygen – and is a homotetramer with a molecular mass of 120 kDa. The enzyme is activated manyfold either in the presence of the anionic detergent SDS below its critical micellar concentration or on exposure to acid-pH. The enhancement of kcat upon activation is accompanied by a marked shift in the pH optimum for the oxidation of t-butyl catechol from 4.5 to 6.0, an increased sensitivity to tropolone, altered susceptibility to proteolytic degradation and decreased thermostability. The Stokes radius of the native enzyme is found to increase from 49.1ą2 to 75.9ą0.6 Ĺ (1 Ĺ=0.1 nm). The activation by SDS and acid-pH results in a localized conformational change that is anchored around the catalytic site of PPO that alters the microenvironment of an essential glutamic residue. Chemical modification of field bean and sweet potato PPO with 1-ethyl-3-(3-dimethylaminopropyl)carbodi-imide followed by kinetic analysis leads to the conclusion that both the enzymes possess a core carboxylate essential to activity. This enhanced catalytic efficiency of PPO, considered as an inducible defence oxidative enzyme, is vital to the physiological defence strategy adapted by plants to insect herbivory and pathogen attack. PMID:16393141

Kanade, Santosh R.; Paul, Beena; Rao, A. G. Appu; Gowda, Lalitha R.

2006-01-01

346

Metabolism of benzene and phenol by a reconstituted purified phenobarbital induced rat liver mixed function oxidase system  

SciTech Connect

Cytochrome P-450 and the electron-donor, NADPH-cytochrome c reductase were isolated from phenobarbital induced rat liver microsomes. Both benzene and its primary metabolite phenol, were substrates for the reconstituted purified phenobarbital induced rat liver mixed function oxidase system. Benzene was metabolized to phenol and the polyhydroxylated metabolites; catechol, hydroquinone and 1,2,4 benzenetriol. Benzene elicited a Type I spectral change upon its interaction with the cytochrome P-450 while phenol's interaction with the cytochrome P-450 produced a reverse Type I spectra. The formation of phenol showed a pH optimum of 7.0 compared with 6.6-6.8 for the production of the polyhyrdoxylated metabolites. Cytochrome P-450 inhibitors, such as metyrapone and SKF 525A, diminished the production of phenol from benzene but not the production of the polyhydroxylated metabolites from phenol. The radical trapping agents, DMSO, KTBA and mannitol, decreased the recovery of polyhydroxylated metabolites, from /sup 14/C-labeled benzene and/or phenol. As KTBA and DMSO interacted with OH. There was a concomitant release of ethylene and methane, which was measured. Desferrioxamine, an iron-chelator and catalase also depressed the recovery of polyhydroxylated metabolites. In summary, benzene and phenol were both substrates for this reconstituted purified enzyme system, but they differed in binding to cytochrome P-450, pH optima and mode of hydroxylation.

Griffiths, J.C.

1986-01-01

347

Direct spectrophotometric assay of monooxygenase and oxidase activities of mushroom tyrosinase in the presence of synthetic and natural substrates.  

PubMed

Alternative substrates were synthesized to allow direct and continuous spectrophotometric assay of both monooxygenase (cresolase) and oxidase (catecholase) activities of mushroom tyrosinase (MT). Using diazo derivatives of phenol, 4-[(4-methoxybenzo)azo]-phenol, 4-[(4-methylphenyl)azo]-phenol, 4-(phenylazo)-phenol, and 4-[(4-hydroxyphenyl)azo]-benzenesulfonamide, and diazo derivatives of catechol 4-[(4-methylbenzo)azo]-1,2-benzenediol, 4-(phenylazo)-1,2-benzenediol, and 4-[(4-sulfonamido)azo]-1,2 benzenediol (SACat), as substrates allows measurement of the rates of the corresponding enzymatic reactions through recording of the depletion rates of substrates at their lambda(max)(s) with the least interference of the intermediates' or products' absorption. Parallel attempts using natural compounds, p-coumaric acid and caffeic acid, as substrates for assaying both activities of MT were comparable approaches. Based on the ensuing data, the electronic effect of the substituent on the substrate activity and the affinity of the enzyme for the substrate are reviewed. Kinetic parameters extracted from the corresponding Lineweaver-Burk plots and advantages of these substrates over the previously used substrates in similar assays of tyrosinases are also presented. PMID:12479831

Haghbeen, Kamahldin; Wue Tan, Eng

2003-01-01

348

Some properties of diamine oxidase from Pisum sativum.  

E-print Network

??Partial purification of diamine oxidase from pea seedlings, Pisum sativum, was accomplished by homogenization of 8-10 day etiolated epicotyl tissue, followed by ammonium sulfate fractionation… (more)

Yamasaki, Edith Fusayo

1967-01-01

349

21 CFR 866.2420 - Oxidase screening test for gonorrhea.  

Code of Federal Regulations, 2013 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2420 Oxidase screening test for gonorrhea. (a) Identification. An...

2013-04-01

350

Carbonic anhydrase inhibitors: guaiacol and catechol derivatives effectively inhibit certain human carbonic anhydrase isoenzymes (hCA I, II, IX and XII).  

PubMed

Abstract Carbonic anhydrases (CAs) are widespread metalloenzymes in higher vertebrates including humans. A series of phenolic compounds, including guaiacol, 4-methylguaiacol, 4-propylguaiacol, eugenol, isoeugenol, vanillin, syringaldehyde, catechol, 3-methyl catechol, 4-methyl catechol and 3-methoxy catechol were investigated for their inhibition of all the catalytically active mammalian isozymes of the Zn(2+)-containing CA (EC 4.2.1.1). All the phenolic compounds effectively inhibited human carbonic anhydrase isoenzymes (hCA I, II, IX and XII), with Kis in the range of 2.20-515.98??M. The various isozymes showed diverse inhibition profiles. Among the tested phenolic derivatives, compounds 4-methyl catechol and 3-methoxy catechol showed potent activity as inhibitors of the tumour-associated transmembrane isoforms (hCA IX and XII) in the submicromolar range, with high selectivity. The results obtained from this research may lead to the design of more effective carbonic anhydrase isoenzyme inhibitors (CAIs) based on such phenolic compound scaffolds. PMID:25373500

Scozzafava, Andrea; Passaponti, Maurizio; Supuran, Claudiu T; Gülçin, Ilhami

2014-11-01

351

Bienzyme biosensors for glucose, ethanol and putrescine built on oxidase and sweet potato peroxidase  

Microsoft Academic Search

Amperometric biosensors for glucose, ethanol, and biogenic amines (putrescine) were constructed using oxidase\\/peroxidase bienzyme systems. The H2O2 produced by the oxidase in reaction with its substrate is converted into a measurable signal via a novel peroxidase purified from sweet potato peels. All developed biosensors are based on redox hydrogels formed of oxidases (glucose oxidase, alcohol oxidase, or amine oxidase) and

Jaime Castillo; Szilveszter Gáspár; Ivan Sakharov; Elisabeth Csöregi

2003-01-01

352

NADPH Oxidase Promotes Neutrophil Extracellular Trap Formation in Pulmonary Aspergillosis  

PubMed Central

NADPH oxidase is a crucial enzyme in antimicrobial host defense and in regulating inflammation. Chronic granulomatous disease (CGD) is an inherited disorder of NADPH oxidase in which phagocytes are defective in generation of reactive oxidant intermediates. Aspergillus species are ubiquitous, filamentous fungi, which can cause invasive aspergillosis, a major cause of morbidity and mortality in CGD, reflecting the critical role for NADPH oxidase in antifungal host defense. Activation of NADPH oxidase in neutrophils can be coupled to the release of proteins and chromatin that comingle in neutrophil extracellular traps (NETs), which can augment extracellular antimicrobial host defense. NETosis can be driven by NADPH oxidase-dependent and -independent pathways. We therefore undertook an analysis of whether NADPH oxidase was required for NETosis in Aspergillus fumigatus pneumonia. Oropharyngeal instillation of live Aspergillus hyphae induced neutrophilic pneumonitis in both wild-type and NADPH oxidase-deficient (p47phox?/?) mice which had resolved in wild-type mice by day 5 but progressed in p47phox?/? mice. NETs, identified by immunostaining, were observed in lungs of wild-type mice but were absent in p47phox?/? mice. Using bona fide NETs and nuclear chromatin decondensation as an early NETosis marker, we found that NETosis required a functional NADPH oxidase in vivo and ex vivo. In addition, NADPH oxidase increased the proportion of apoptotic neutrophils. Together, our results show that NADPH oxidase is required for pulmonary clearance of Aspergillus hyphae and generation of NETs in vivo. We speculate that dual modulation of NETosis and apoptosis by NADPH oxidase enhances antifungal host defense and promotes resolution of inflammation upon infection clearance. PMID:24549323

Röhm, Marc; Grimm, Melissa J.; D'Auria, Anthony C.; Almyroudis, Nikolaos G.

2014-01-01

353

Natural variation of the rice blast resistance gene Pi-ta in Oryza species and its corresponding avirulence gene AVR-Pita in Magnaporthe oryzae  

Technology Transfer Automated Retrieval System (TEKTRAN)

The Pi-ta gene prevents the infections of M. oryzae races containing the corresponding avirulence gene AVR-Pita in a gene-for-gene manner. Pi-ta is a putative NBS type major resistance gene, and can directly recognize the AVR-Pita putative metalloprotease in triggering effective resistance. We hav...

354

Evidence for a susceptibility locus for panic disorder near the catechol- O-methyltransferase gene on chromosome 22  

Microsoft Academic Search

Background: A well-characterized single nucleotide polymorphism (472G\\/A-Val\\/Met-SNP8) in the coding sequence of the catechol-O-methyltransferase (COMT) gene leads to a three- to fourfold difference in enzymatic activity and clinical and animal studies suggest a role in anxiety states like panic disorder.Methods: Subjects from 70 panic disorder pedigrees, and 83 “triads”, were genotyped at seven single nucleotide polymorphisms (SNPs), polymorphic microsatellites in

Steven P. Hamilton; Susan L. Slager; Gary A. Heiman; Zemin Deng; Fatemeh Haghighi; Donald F. Klein; Susan E. Hodge; Myrna M. Weissman; Abby J. Fyer; James A. Knowles

2002-01-01

355

Genotype Determining Low Catechol-O-Methyltransferase Activity as a Risk Factor for Obsessive-Compulsive Disorder  

Microsoft Academic Search

In the present study, we address the role of the gene for catechol-O-methyltransferase (COMT), a key modulator of dopaminergic and noradrenergic neurotransmission, in the genetic predisposition to obsessive-compulsive disorder (OCD). We show that a common functional allele of this gene, which results in a 3- to 4-fold reduction in enzyme activity, is significantly associated in a recessive manner with susceptibility

Maria Karayiorgou; Margaret Altemus; Brandi L. Galke; David Goldman; Dennis L. Murphy; Jurg Ott; Joseph A. Gogos

1997-01-01

356

Electrocatalytic oxidation of dihydronicotineamide adenine dinucleotide on gold electrode modified with catechol-terminated alkanethiol self-assembly.  

PubMed

Synthesis of a mercaptoundecaneamide derivative having a terminus of catechol is described. FT-IR spectroscopic characterization showed that the new molecular entry simply undergoes molecular self-assembly on Au substrate surfaces promoting intra- and intermolecular hydrogen bonds to form well-packed monolayers. Cyclic voltammetric (CV) measurements on the monolayer-modified Au electrode revealed that the surface adlayer possesses specific electrochemical activity due to the reversible catechol/o-quinone redox reaction having characteristics of a surface process and also pH-dependence in its formal potential (59 mV per pH). Detailed analysis of CVs gave fundamental electrochemical parameters including the electroactive surface coverage (0.20-0.24 nmol cm(-2)), the transfer coefficients (0.24 in oxidation and 0.81 in reduction), and also the electron transfer rate constant (1.10-2.76 s(-1)). These data were almost consistent to those seen in literature. We have also found that the catechol monolayer modified electrode exhibits an electrocatalytic function in NADH oxidation. That is, the faradaic current appeared reinforcingly at around the same potential where catechol function is oxidized in the monolayer and increased with an increase in the NADH concentration from 1 to 5 mM, and then reached to a plateau indicating a catalyzed reaction pathway. Detailed analyses revealed that the present system could be characterized by its weak stability of the intermediate compound formed and prompt reaction rate compared with the previously reported chemically modified electrode (CME) systems. We think this type of achievement should be important for the basics of biosensors that rely on dehydrogenase enzymes. PMID:18539170

Nakano, Koji; Ohkubo, Kimihiko; Taira, Hiroaki; Takagi, Makoto; Imato, Toshihiko

2008-06-30

357

Pharmacogenetics of Modafinil After Sleep Loss: Catechol-O-Methyltransferase Genotype Modulates Waking Functions But Not Recovery Sleep  

Microsoft Academic Search

Sleep loss impairs waking functions and is homeostatically compensated in recovery sleep. The mechanisms underlying the consequences of prolonged wakefulness are unknown. The stimulant modafinil may promote primarily dopaminergic neurotransmission. Catechol-O-methyltransferase (COMT) catalyzes the breakdown of cerebral dopamine. A functional Val158Met polymorphism reduces COMT activity, and Val\\/Val homozygous individuals presumably have lower dopaminergic signaling in the prefrontal cortex than do

S Bodenmann; S Xu; UFO Luhmann; M Arand; W Berger; HH Jung; HP Landolt

2009-01-01

358

Oxidovanadium catechol complexes: radical versus non-radical states and redox series.  

PubMed

A new family of oxidovanadium complexes, [(L1(R))(VO)(L(R(')))] (R = H, R' = H, 1; R = H, R' = -CMe3, 2; R = H, R' = Me, 3; R = -CMe3, R' = H, 4 and R = -CMe3, R' = -CMe3, 5), incorporating tridentate L1(R)H ligands (L1(R)H = 2,4-di-R-6-{(2-(pyridin-2-yl)hydrazono)methyl}phenol) and substituted catechols (L(R('))H2) was substantiated. The V-Ophenolato (cis to V?O), V-OCAT (cis to V?O) and V-OCAT (trans to V?O) lengths span the ranges, 1.894(2)-1.910(2), 1.868(2)-1.887(2), and 2.120(2)-2.180(2) Ĺ. The metrical oxidation states (MOS) of the catechols in 1-5 are fractional and vary from -1.43 to -1.60. The (51)V isotropic chemical shifts of solids and solutions of 1-5 are deshielded ((51)V CP MAS: -19.8 to +248.6; DMSO-d6: +173.9 to +414.55 ppm). The closed shell singlet (CSS) solutions of 1-5 are unstable due to open shell singlet (OSS) perturbations. The ground electronic states of 1-5 are defined by the resonance contribution of the catecholates (L(R('))CAT(2-)) and L(R('))SQ(-•) coordinated to the [VO](3+) and [VO](2+) ions. 1-5 are reversibly reducible by one electron at -(0.58-0.87) V, referenced vs ferrocenium/ferrocene, to VO(2+) complexes, [(L1(R-))(VO(2+))(L(R('))CAT(2-))](-) [1-5](-). 1-5 display another quasi-reversible or irreversible reduction wave at -(0.80-1.32) V due to the formation of hydrazone anion radical (L1(R2-•)) complexes, [(L1(R2-•))(VO(2+))(L(R('))CAT(2-))](2-), [1-5](2-), with S = 1 authenticated by the unrestricted density functional theory (DFT) calculations on 1(2-) and 3(2-) ions. Frozen glasses electron paramagnetic resonance (EPR) spectra of [1-5](-) ions [e.g., for 2, g|| = 1.948, g? = 1.979, A|| = 164, A? = 60] affirmed that [1-5](-) ions are the [VO](2+) complexes of L(R')CAT(2-). Spectro-electrochemical measurements and time-dependent DFT (TD DFT) calculations on 1, 3, 1(-), 3(-), and 1(2-) disclosed that the near infrared (NIR) absorption bands of 1-5 at 800 nm are due to the CSS-OSS metal to ligand charge transfer which are red-shifted in the solid state and disappear in [1-5](-) and [1-5](2-) ions. PMID:23786369

Kundu, Suman; Maity, Suvendu; Weyhermüller, Thomas; Ghosh, Prasanta

2013-07-01

359

Molecular breeding of the Mureka-non-forming sake koji mold from Aspergillus oryzae by the disruption of the mreA gene.  

PubMed

Mureka-non-forming sake koji molds were constructed from an Aspergillus oryzae industrial strain by the disruption of the mreA gene using a host-vector system with the ptrA gene as a dominant selectable marker. All of the mreA gene disruptants obtained retained the advantages of the host strain in terms of the brewing characteristics, while their isoamyl alcohol oxidase (IAAOD) activities were significantly lower than that of the host strain. Sake brewing was successfully carried out using the koji prepared with the disruptants, followed by storage of the resultant non-pasteurized sake (nama-shu). The isovaleraldehyde (i-Val) concentration in the sake brewed the host strain increased rapidly and reached the threshold values for mureka, 1.8 ppm and 2.6 ppm after storage at 20 degrees C for 42 d and 63 d, respectively, while those of the disruptants were less than 0.5 ppm even after storage at 20 degrees C or 30 degrees C for 63 d. In the sensory evaluation of the sake stored at 20 degrees C or 30 degrees C for 63 d, all members of the panel recognized the strong mureka flavor of the sake brewed with the host strain, while they did not detect this flavor in the sake brewed with the disruptants. Thus, we concluded that the mreA gene disruptants can be used for the production of sake in which mureka is not formed. PMID:16233364

Kubodera, Takafumi; Yamashita, Nobuo; Nishimura, Akira

2003-01-01

360

Biomimetic PEG-catecholates for stabile antifouling coatings on metal surfaces: applications on TiO2 and stainless steel.  

PubMed

Trimeric catecholates have been designed for the stable immobilization of effector molecules on metal surfaces. The design of these catecholates followed a biomimetic approach and was inspired by natural multivalent metal binders, such as mussel adhesion proteins (MAPs) and siderophores. Three catecholates have been conjugated to central scaffolds based on adamantyl or trisalkylmethyl core structures. The resulting triscatecholates have been immobilized on TiO2 and stainless steel. In a proof of concept study we have demonstrated the high stability of the resulting nanolayers at neutral and slightly acidic pH. Furthermore, polyethylene glycol (PEG) conjugates of our triscatecholates have been synthesized and were immobilized on TiO2 and stainless steel. The PEG coated surfaces showed excellent antifouling properties upon exposure to human blood and bacteria as demonstrated by fluorescence microscopy, ellipsometry and a bacterial assay with Staphylococcus epidermidis. In addition, our PEG-triscatecholates showed no cytotoxicity against bone-marrow stem cells on TiO2. PMID:24632391

Khalil, Faiza; Franzmann, Elisa; Ramcke, Julian; Dakischew, Olga; Lips, Katrin S; Reinhardt, Alexander; Heisig, Peter; Maison, Wolfgang

2014-05-01

361

Metrical oxidation states of 2-amidophenoxide and catecholate ligands: structural signatures of metal-ligand ? bonding in potentially noninnocent ligands.  

PubMed

Catecholates and 2-amidophenoxides are prototypical "noninnocent" ligands which can form metal complexes where the ligands are best described as being in the monoanionic (imino)semiquinone or neutral (imino)quinone oxidation state instead of their closed-shell dianionic form. Through a comprehensive analysis of structural data available for compounds with these ligands in unambiguous oxidation states (109 amidophenolates, 259 catecholates), the well-known structural changes in the ligands with oxidation state can be quantified. Using these correlations, an empirical "metrical oxidation state" (MOS) which gives a continuous measure of the apparent oxidation state of the ligand can be determined based on least-squares fitting of its C-C, C-O, and C-N bond lengths to this single parameter (a simple procedure for doing so is provided via a spreadsheet in the Supporting Information). High-valent d(0) metal complexes, particularly those of vanadium(V) and molybdenum(VI), have ligands with unexpectedly positive, and generally nonintegral, MOS values. The structural effects in these complexes are attributed not to electron transfer, but rather to amidophenoxide- or catecholate-to-metal ? bonding, an interpretation supported by the systematic variation of the MOS values as a function of the degree of competition with the other ?-donating groups in the structures. PMID:22260321

Brown, Seth N

2012-02-01

362

Iron(III)-chelating properties of the novel catechol O-methyltransferase inhibitor entacapone in aqueous solution.  

PubMed

The iron(III) complex formation of entacapone, a novel catechol O-methyltransferase (COMT) inhibitor, has been studied at 25 degrees C in aqueous 0.1 mol/L NaCl solution by using the electromotive force titration method. Entacapone functions as a bidentate ligand chelating through the catecholate oxygen atoms and forms stable iron(III) complexes with the formation constant of a tris complex: log beta-613 ([FeL3(3-)][H]6+/[Fe3+][H2L]3) = -6.9 +/- 0.1. Distribution curves show that entacapone is highly effective for iron(III) in moderately dilute solution (10(-3) mol/L) whereas in very dilute solution (10(-6) mol/L) the iron hydroxo complexes together with FeL3(3-) dominate under physiological pH 7.4. Comparison of iron(III) species distribution in a competitive two-ligand entacapone-catechol system reveals that the complexation of entacepone is favored at high and low dilution. PMID:9232524

Orama, M; Tilus, P; Taskinen, J; Lotta, T

1997-07-01

363

Amperometric catechol biosensor based on laccase immobilized on nitrogen-doped ordered mesoporous carbon (N-OMC)/PVA matrix  

NASA Astrophysics Data System (ADS)

A functionalized nitrogen-containing ordered mesoporous carbon (N-OMC), which shows good electrical properties, was synthesized by the carbonization of polyaniline inside a SBA-15 mesoporous silica template. Based on this, through entrapping laccase onto the N-OMC/polyvinyl alcohol (PVA) film a facilely fabricated amperometric biosensor was developed. Laccase from Trametes versicolor was assembled on a composite film of a N-OMC/PVA modified Au electrode and the electrochemical behavior was investigated. The results indicated that the N-OMC modified electrode exhibits electrical properties towards catechol. The optimum experimental conditions of a biosensor for the detection of catechol were studied in detail. Under the optimal conditions, the sensitivity of the biosensor was 0.29 A*M-1 with a detection limit of 0.31 ?M and a linear detection range from 0.39 ?M to 8.98 ?M for catechol. The calibration curve followed the Michaelis-Menten kinetics and the apparent Michaelis-Menten \\left( K_{M}^{app} \\right) was 6.28 ?M. This work demonstrated that the N-OMC/PVA composite provides a suitable support for laccase immobilization and the construction of a biosensor.

Guo, Meiqing; Wang, Hefeng; Huang, Di; Han, Zhijun; Li, Qiang; Wang, Xiaojun; Chen, Jing

2014-06-01

364

A solid-state electrochemiluminescence sensing platform for detection of catechol based on novel luminescent composite nanofibers.  

PubMed

A solid-state electrochemiluminescence (ECL) sensing platform based on the novel luminescent composite nanofibers for detection of catechol has been developed. The carboxylated multi-walled carbon nanotubes (MWNTs) and ruthenium(II) tris-(bipyridine) (Ru(bpy)3(2+)) doped nylon 6 (PA6) luminescent composite nanofibers (Ru-MWNTs-PA6) were successfully fabricated by a one-step electrospinning technique. The Ru-MWNTs-PA6 nanofibers, with unique 3D nanostructure, large specific surface area and a larger amount of immobilized-Ru(bpy)3(2+), maintained the photoelectric properties of the Ru(bpy)3(2+) ions and exhibited excellent ECL behaviors on glassy carbon (GC) electrode. As a solid-state ECL sensing platform, the Ru-MWNTs-PA6 nanofibers can sensitively detect low concentration catechol by monitoring the phenol-dependent ECL intensity change. The detection limit for catechol is 1.0 nM, which is comparable or better than that in the reported assays. The solid-state ECL sensor displayed wide linear range, high sensitivity and good stability. It holds promise for the electrospun nanofibers-based ECL sensors have a great potential for routine analyses. PMID:23598202

Wang, Xiaoying; Wang, Xiaobing; Gao, Sumeng; Zheng, Yi; Tang, Meng; Chen, Baoan

2013-03-30

365

Plasma diamine oxidase levels in pregnancy complicated by threatened abortion  

Microsoft Academic Search

Plasma diamine oxidase levels were assayed in 66 patients who presented with pregnancy complicated by threatened abortion. Levels within the normal range were associated with continuing pregnancies, whereas levels below the normal range were associated with subsequent abortion. Among those patients in whom gestation was greater than eight weeks, 66.6% of diamine oxidase levels correctly predicted the pregnancy outcome. Assay

M Legge; G B Duff

1981-01-01

366

Diamine oxidase content in urine of patients with renal failure  

Microsoft Academic Search

Diamine oxidase activity was determined in twentyseven samples collected from normal subjects and from patients with renal failure. The enzyme activity was absent or very low in the urine samples of normal subjects. The highest diamine oxidase activity was found in the patients affected with nephrosis, the Fanconi syndrome and renal transplantation, showing a relationship between urinary enzymatic activity and

D. Giarnieri; M. T. Costa; V. Giarnieri; B. Mondovi

1985-01-01

367

Factors regulating production of glucose oxidase by Aspergillus niger  

Microsoft Academic Search

Certain factors affecting production of extracellular and cell-bound glucose oxidase by Aspergillus niger were investigated. The intention was to maximize total glucose oxidase activity of academic and potential commercial application by the selection of the appropriate strain and consecutive optimization of growth media and conditions. It was possible to identify combinations resulting in the utilization of molasses as the best

D. G. Hatzinikolaou; B. J. Macris

1995-01-01

368

Diamine Oxidase: An Overview of Historical, Biochemical and Functional Aspects  

Microsoft Academic Search

This article is a review of the historical, biochemical, and functional aspects of the enzyme diamine oxidase (DAO). The amine oxidase DAO, formerly called histaminase, is found in various tissues, but is especially active in the intestinal mucosa. Its function is the oxidative deaminating of several polyamines, essential substances for cell proliferation. DAO is thus a regulating enzyme in rapidly

M. C. J. Wolvekamp; R. W. F. de Bruin

1994-01-01

369

Genetics Home Reference: Peroxisomal acyl-CoA oxidase deficiency  

MedlinePLUS

... oxidase. This enzyme is found in sac-like cell structures (organelles) called peroxisomes, which contain a variety of enzymes that break down many different substances. The peroxisomal straight-chain acyl-CoA oxidase ... gene mutations prevent the peroxisomal straight-chain ...

370

Polyphenol oxidases in plants and fungi: Going places? A review  

Microsoft Academic Search

The more recent reports on polyphenol oxidase in plants and fungi are reviewed. The main aspects considered are the structure, distribution, location and properties of polyphenol oxidase (PPO) as well as newly discovered inhibitors of the enzyme. Particular stress is given to the possible function of the enzyme. The cloning and characterization of a large number of PPOs is surveyed.

Alfred M. Mayer

2006-01-01

371

Dephenolization of industrial wastewaters catalyzed by polyphenol oxidase  

Microsoft Academic Search

A new enzymatic method for the removal of phenols from industrial aqueous effluents has been developed. The method uses the enzyme polyphenol oxidase which oxidizes phenols to the corresponding o-quinones; the latter then undergo a nonenzymatic polymerization to form water-insoluble aggregates. Therefore, the enzyme in effect precipitates phenols from water. Polyphenol oxidase has been found to nearly completely dephenolize solutions

Stuart C. Atlow; Lucia Bonadonna-Aparo; Alexander M. Klibanov

1984-01-01

372

Methods and approaches to study plant mitochondrial alternative oxidase  

Microsoft Academic Search

The alternative oxidase is a non-proton motive 'alternative' to electron transport through the cytochrome pathway. Despite its wasteful nature in terms of energy conservation, the path- way is likely present throughout the plant kingdom and ap- pears to be expressed in most plant tissues. A small alterna- tive oxidase gene family exists, the members of which are differentially expressed in

Allison E. McDonald; Stephen M. Sieger; Greg C. Vanlerberghe

2002-01-01

373

Human kidney diamine oxidase: heterologous expression, purification, and characterization  

Microsoft Academic Search

Human kidney diamine oxidase has been overexpressed as a secreted enzyme under the control of a metallothionein promoter in Drosophila S2 cell culture. This represents the first heterologous overexpression and purification of a catalytically active, recombinant mammalian copper-containing amine oxidase. A rapid and highly efficient purification protocol using chromatography on heparin affinity, hydroxyapatite, and gel filtration media allows for the

Bradley O. Elmore; John A. Bollinger; David M. Dooley

2002-01-01

374

Diamine oxidase in relation to diamine and polyamine metabolism  

Microsoft Academic Search

Diamine oxidase catalyzes the oxidative deamination of short chain aliphatic diamines, like putrescine, and histamine. The enzyme is rate-limiting in the terminal catabolism of polyamines, which are endogenous polycations important for cell growth and differentiation. This review examines the behavior of diamine oxidase in mammalian tissues in relation to diamine and polyamine metabolism under physiological and pathological conditions. The role

Angela Sessa; Antonio Perin

1994-01-01

375

DETERMINATION OF DIAMINE OXIDASE ACTIVITY BY LIQUID SCINTILLATION COUNTING  

Microsoft Academic Search

A rapid method for diamine oxidase assay is described. The method is ; based on the formation of radioactive toluene-extractable end product(s) from the ; actlon of dlamlne oxidase on cadaverine-Cš⁴. The end products are ; extracted directly into toluene and assayed in a liquid scintillation ; spectrometer. The method is applicable using radioactive putrescine as ; substrate, but does

T. Okuyama; Y. Kobayashi

1961-01-01

376

Eosinophil diamine oxidase activity in acute inflammation in humans  

Microsoft Academic Search

Eosinophil diamine oxidase, histaminase, activity was assayed in acute inflammatory states and correlated to disease activity. Correlation to serum and urine histamine, metabolites of histamine and granulocyte histamine metabolizing enzymes was also studied. Using a radiochromatagraphic assay, diamine oxidase, histaminese, activity was determined in human peripheral blood eosinophils from patients with acute inflammatory states including active asthma, cold-induced urticaria and

James Jay Herman; H. RICHTER; R. HESTERBERG; J. SCHMIDT; D. LECAVALIER; P. RYAN

1982-01-01

377

Alternative oxidase in animals: unique characteristics and taxonomic distribution  

Microsoft Academic Search

SUMMARY Alternative oxidase (AOX), a ubiquinol oxidase, introduces a branch point into the respiratory electron transport chain, bypassing complexes III and IV and resulting in cyanide-resistant respiration. Previously, AOX was thought to be limited to plants and some fungi and protists but recent work has demonstrated the presence of AOX in most kingdoms of life, including animals. In the present

Allison E. McDonald; Greg C. Vanlerberghe; James F. Staples

2009-01-01

378

Comparative Chemistry of Aspergillus oryzae (RIB40) and A. flavus (NRRL 3357)  

PubMed Central

Aspergillus oryzae and A. flavus are important species in industrial biotechnology and food safety and have been some of the first aspergilli to be fully genome sequenced. Bioinformatic analysis has revealed 99.5% gene homology between the two species pointing towards a large coherence in the secondary metabolite production. In this study we report on the first comparison of secondary metabolite production between the full genome sequenced strains of A. oryzae (RIB40) and A. flavus (NRRL 3357). Surprisingly, the overall chemical profiles of the two strains were mostly very different across 15 growth conditions. Contrary to previous studies we found the aflatrem precursor 13-desoxypaxilline to be a major metabolite from A. oryzae under certain growth conditions. For the first time, we additionally report A. oryzae to produce parasiticolide A and two new analogues hereof, along with four new alkaloids related to the A. flavus metabolites ditryptophenalines and miyakamides. Generally the secondary metabolite capability of A. oryzae presents several novel end products likely to result from the domestication process from A. flavus. PMID:24957367

Rank, Christian; Klejnstrup, Marie Louise; Petersen, Lene Maj; Kildgaard, Sara; Frisvad, Jens Christian; Gotfredsen, Charlotte Held; Larsen, Thomas Ostenfeld

2012-01-01

379

Genome-scale analysis of the high-efficient protein secretion system of Aspergillus oryzae  

PubMed Central

Background The koji mold, Aspergillus oryzae is widely used for the production of industrial enzymes due to its particularly high protein secretion capacity and ability to perform post-translational modifications. However, systemic analysis of its secretion system is lacking, generally due to the poorly annotated proteome. Results Here we defined a functional protein secretory component list of A. oryzae using a previously reported secretory model of S. cerevisiae as scaffold. Additional secretory components were obtained by blast search with the functional components reported in other closely related fungal species such as Aspergillus nidulans and Aspergillus niger. To evaluate the defined component list, we performed transcriptome analysis on three ?-amylase over-producing strains with varying levels of secretion capacities. Specifically, secretory components involved in the ER-associated processes (including components involved in the regulation of transport between ER and Golgi) were significantly up-regulated, with many of them never been identified for A. oryzae before. Furthermore, we defined a complete list of the putative A. oryzae secretome and monitored how it was affected by overproducing amylase. Conclusion In combination with the transcriptome data, the most complete secretory component list and the putative secretome, we improved the systemic understanding of the secretory machinery of A. oryzae in response to high levels of protein secretion. The roles of many newly predicted secretory components were experimentally validated and the enriched component list provides a better platform for driving more mechanistic studies of the protein secretory pathway in this industrially important fungus. PMID:24961398

2014-01-01

380

Organization of chromosome ends in the rice blast fungus, Magnaporthe oryzae  

PubMed Central

Eukaryotic pathogens of humans often evade the immune system by switching the expression of surface proteins encoded by subtelomeric gene families. To determine if plant pathogenic fungi use a similar mechanism to avoid host defenses, we sequenced the 14 chromosome ends of the rice blast pathogen, Magnaporthe oryzae. One telomere is directly joined to ribosomal RNA-encoding genes, at the end of the ?2 Mb rDNA array. Two are attached to chromosome-unique sequences, and the remainder adjoin a distinct subtelomere region, consisting of a telomere-linked RecQ-helicase (TLH) gene flanked by several blocks of tandem repeats. Unlike other microbes, M.oryzae exhibits very little gene amplification in the subtelomere regions—out of 261 predicted genes found within 100 kb of the telomeres, only four were present at more than one chromosome end. Therefore, it seems unlikely that M.oryzae uses switching mechanisms to evade host defenses. Instead, the M.oryzae telomeres have undergone frequent terminal truncation, and there is evidence of extensive ectopic recombination among transposons in these regions. We propose that the M.oryzae chromosome termini play more subtle roles in host adaptation by promoting the loss of terminally-positioned genes that tend to trigger host defenses. PMID:16963777

Rehmeyer, Cathryn; Li, Weixi; Kusaba, Motoaki; Kim, Yun-Sik; Brown, Doug; Staben, Chuck; Dean, Ralph; Farman, Mark

2006-01-01

381

Mapping two major resistance genes in an indica cultivar Zhe733 to the race IE-1K of Magnaporthe oryzae  

Technology Transfer Automated Retrieval System (TEKTRAN)

Resistance (R) genes in rice confer resistance to races of Magnaporthe oryzae that contain the corresponding avirulence genes. The race IE-1K of M. oryzae recovered from the southern US overcomes R gene Pi-ta. The objectives of the present study were to identify new resistance sources to IE-1k an...

382

Preliminary assessment of resistance among U.S. wheat cultivars to the Triticum pathotype of Magnaporthe oryzae  

Technology Transfer Automated Retrieval System (TEKTRAN)

Magnaporthe oryzae is the causal agent of blast disease on several graminaceous plants. The M. oryzae population causing wheat blast has not been officially reported outside South America. U.S. wheat production is at risk to this pathogen if it is introduced and established. Proactive testing of U.S...

383

Expression profiling of common and specific defense responses of rice to Magnaporthe oryzae infection using deep sequencing technologies  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rice blast caused by Magnaporthe oryzae is a serious disease in rice production. Wild type Nipponbare and transgenic rice plants (carrying the Pi9 blast resistance gene) were challenged with the rice blast strain KJ201 to identify the early, mid and late host responses to M. oryzae infection at the ...

384

Diversification and evolution of the avirulence gene AVR-Pita1 in field isolates of Magnaporthe oryzae  

Technology Transfer Automated Retrieval System (TEKTRAN)

The study of the evolution of the AVR-Pita1 genes should benefit the deployment of the resistance gene Pi-ta for protecting rice production. The AVR-Pita1 avirulence gene in races of Magnaporthe oryzae triggers an effective resistance response when M. oryzae infects rice plants that contain the Pi-...

385

Proteomics study of silver nanoparticles toxicity on Oryza sativa L.  

PubMed

The increasing use of silver nanoparticles, (AgNPs), will inevitably result in their release into the environment and thereby cause the exposure to plants. It was claimed that using AgNPs is a safe and efficient method to preserve and treat agents of disease in agriculture. This study tries to understand the protein populations and sub-populations and follow up environmental AgNPs stresses. To accomplish these, the action of homemade spherical AgNPs colloidal suspension against Oryza sativa L. was investigated by a proteomic approach (2-DE and NanoLC/FT-ICR MS identification). Twenty-eight responsive (decrement/increment in abundance) proteins were identified. Proteomic results revealed that an exposure of O. sativa L., root with different concentrations of AgNPs resulted in an accumulation of protein precursors, indicative of the dissipation of a proton motive force. The identified proteins are involved in oxidative stress tolerance, Ca(2+) regulation and signaling, transcription and protein degradation, cell wall and DNA/RNA/protein direct damage, cell division and apoptosis. The expression pattern of these proteins and their possible involvement in the nontoxicity mechanisms were discussed. PMID:25124680

Mirzajani, Fateme; Askari, Hossein; Hamzelou, Sara; Schober, Yvonne; Römpp, Andreas; Ghassempour, Alireza; Spengler, Bernhard

2014-10-01

386

Rice (Oryza sativa) centromeric regions consist of complex DNA  

PubMed Central

Rice bacterial artificial chromosome clones containing centromeric DNA were isolated by using a DNA sequence (pSau3A9) that is present in the centromeres of Gramineae species. Seven distinct repetitive DNA elements were isolated from a 75-kilobase rice bacterial artificial chromosome clone. All seven DNA elements are present in every rice centromere as demonstrated by fluorescence in situ hybridization. Six of the elements are middle repetitive, and their copy numbers range from ?50 to ?300 in the rice genome. Five of these six middle repetitive DNA elements are present in all of the Gramineae species, and the other element is detected only in species within the Bambusoideae subfamily of Gramineae. All six middle repetitive DNA elements are dispersed in the centromeric regions. The seventh element, the RCS2 family, is a tandem repeat of a 168-bp sequence that is represented ?6,000 times in the rice genome and is detected only in Oryza species. Fiber-fluorescence in situ hybridization analysis revealed that the RCS2 family is organized into long uninterrupted arrays and resembles previously reported tandem repeats located in the centromeres of human and Arabidopsis thaliana chromosomes. We characterized a large DNA fragment derived from a plant centromere and demonstrated that rice centromeres consist of complex DNA, including both highly and middle repetitive DNA sequences. PMID:9653153

Dong, Fenggao; Miller, Joseph T.; Jackson, Scott A.; Wang, Guo-Liang; Ronald, Pamela C.; Jiang, Jiming

1998-01-01

387

The Population Structure of African Cultivated Rice Oryza glaberrima (Steud.)  

PubMed Central

Genome-wide linkage disequilibrium (LD) was investigated for 198 accessions of Oryza glaberrima using 93 nuclear microsatellite markers. Significantly elevated levels of LD were detected, even among distantly located markers. Free recombination among loci at the population genetic level was shown (1) by a lack of decay in LD among markers on the same chromosome and (2) by a strictly increasing composite likelihood function for the recombination parameter. This suggested that the elevation in LD was due not to physical linkage but to other factors, such as population structure. A Bayesian clustering analysis confirmed this hypothesis, indicating that the sample of O. glaberrima in this study was subdivided into at least five cryptic subpopulations. Two of these subpopulations clustered with control samples of O. sativa, subspecies indica and japonica, indicating that some O. glaberrima accessions represent admixtures. The remaining three O. glaberrima subpopulations were significantly associated with specific combinations of phenotypic traits—possibly reflecting ecological adaptation to different growing environments. PMID:15545652

Semon, Mande; Nielsen, Rasmus; Jones, Monty P.; McCouch, Susan R.

2005-01-01

388

Ascorbic acid and L-gulonolactone oxidase in lagomorphs.  

PubMed

1. The activity of L-gulonolactone oxidase (EC 1.1.3.8) in the liver of eastern cottontail rabbits (Sylvilagus floridanus) is about 10-fold greater in winter than in summer. 2. L-gulonolactone oxidase activity is low and tissue ascorbate high during all seasons in snowshoe hares (Lepus americanus). 3. Liver contents of ascorbate fall to low levels in L. americanus fed on rabbit chow in the laboratory. 4. The activity of L-gulonolactone oxidase in liver of Sylvilagus and Oryctolagus is depressed by feeding high levels of L-ascorbic acid. 5. The New Zealand White breed of domestic rabbit (Oryctolagus cuniculus) has considerably higher levels of L-gulonolactone oxidase and liver ascorbate than does the Dutch breed. 6. In a wild population of Oryctolagus sampled in Australia L-gulonolactone oxidase levels were intermediate between those of the two domestic breeds and more variable than either. PMID:318384

Jenness, R; Birney, E C; Ayaz, K L

1978-01-01

389

Xanthine oxidase inhibitors from Garcinia esculenta twigs.  

PubMed

The EtOAc-soluble portion of the 80?% (v/v) EtOH extract from the twigs of Garcinia esculenta exhibited strong xanthine oxidase inhibition in vitro. Bioassay-guided purification led to the isolation of 1,3,6,7-tetrahydroxyxanthone (3) and griffipavixanthone (8) as the main xanthine oxidase inhibitors, along with six additional compounds (1, 2, 4-7), including two new compounds (1 and 2). This enzyme inhibition was dose dependent with an IC50 value of approximately 1.2?ľM for 3 and 6.3?ľM for 8. The inhibitory activity of 3 was stronger than the control allopurinol (IC50 value: 5.3?ľM). To our knowledge, compound 8 is the first bixanthone that demonstrated potent XO inhibitory activity in vitro. The structures of the new compounds were established by spectroscopic analysis, and the optical properties and absolute stereochemistry of racemic (ą) esculentin A (2) were further determined by the calculation of the DP4 probability and analysis of its MTPA ester derivatives. PMID:25340468

Zhu, Lun-Lun; Fu, Wen-Wei; Watanabe, Shimpei; Shao, Yi-Nuo; Tan, Hong-Sheng; Zhang, Hong; Tan, Chang-Heng; Xiu, Yan-Feng; Norimoto, Hisayoshi; Xu, Hong-Xi

2014-12-01

390

Cytochrome c oxidase dysfunction in oxidative stress.  

PubMed

Cytochrome c oxidase (CcO) is the terminal oxidase of the mitochondrial electron transport chain. This bigenomic enzyme in mammals contains 13 subunits of which the 3 catalytic subunits are encoded by the mitochondrial genes. The remaining 10 subunits with suspected roles in the regulation, and/or assembly, are coded by the nuclear genome. The enzyme contains two heme groups (heme a and a3) and two Cu(2+) centers (Cu(2+) A and Cu(2+) B) as catalytic centers and handles more than 90% of molecular O(2) respired by the mammalian cells and tissues. CcO is a highly regulated enzyme which is believed to be the pacesetter for mitochondrial oxidative metabolism and ATP synthesis. The structure and function of the enzyme are affected in a wide variety of diseases including cancer, neurodegenerative diseases, myocardial ischemia/reperfusion, bone and skeletal diseases, and diabetes. Despite handling a high O(2) load the role of CcO in the production of reactive oxygen species still remains a subject of debate. However, a volume of evidence suggests that CcO dysfunction is invariably associated with increased mitochondrial reactive oxygen species production and cellular toxicity. In this paper we review the literature on mechanisms of multimodal regulation of CcO activity by a wide spectrum of physiological and pathological factors. We also review an array of literature on the direct or indirect roles of CcO in reactive oxygen species production. PMID:22841758

Srinivasan, Satish; Avadhani, Narayan G

2012-09-15

391

Genome-wide identification of lineage-specific genes in Arabidopsis, Oryza and Populus  

SciTech Connect

Protein sequences were compared among Arabidopsis, Oryza and Populus to identify differential gene (DG) sets that are in one but not the other two genomes. The DG sets were screened against a plant transcript database, the NR protein database and six newly-sequenced genomes (Carica, Glycine, Medicago, Sorghum, Vitis and Zea) to identify a set of species-specific genes (SS). Gene expression, protein motif and intron number were examined. 192, 641 and 109 SS genes were identified in Arabidopsis, Oryza and Populus, respectively. Some SS genes were preferentially expressed in flowers, roots, xylem and cambium or up-regulated by stress. Six conserved motifs in Arabidopsis and Oryza SS proteins were found in other distant lineages. The SS gene sets were enriched with intronless genes. The results reflect functional and/or anatomical differences between monocots and eudicots or between herbaceous and woody plants. The Populus-specific genes are candidates for carbon sequestration and biofuel research.

Yang, Xiaohan [ORNL; Jawdy, Sara [ORNL; Tschaplinski, Timothy J [ORNL; Tuskan, Gerald A [ORNL

2009-01-01

392

Neutrophil chemotactic responses induced by fresh and swollen Rhizopus oryzae spores and Aspergillus fumigatus conidia.  

PubMed Central

With the induction of germination, Rhizopus oryzae spores and Aspergillus fumigatus conidia activate the complement system and induce neutrophil chemotaxis. In contrast, freshly isolated R. oryzae spores did not induce neutrophil migration into lung tissue of mice after intranasal inoculation. Moreover, in microchemotaxis assays neither fresh R. oryzae spores nor A. fumigatus conidia activated sera to stimulate human neutrophil chemotaxis above control migration until at least 10(7) or 10(8) spores or conidia per ml of sera were used. The increased generation of chemotactic factors by swollen spores and conidia was not due to an increased surface area, as there was decreased neutrophil chemotactic response to Rhizopus or Aspergillus hyphae when compared with swollen spores or conidia. PMID:3157647

Waldorf, A R; Diamond, R D

1985-01-01

393

Triterpenoid glycosides from Medicago sativa as antifungal agents against Pyricularia oryzae.  

PubMed

The antifungal properties of saponin mixtures from alfalfa (Medicago sativa L.) tops and roots, the corresponding mixtures of prosapogenins from tops, and purified saponins and sapogenins against the causal agent of rice blast Pyricularia oryzae isolates are presented. In vitro experiments highlighted a range of activities, depending upon the assayed metabolite. The antifungal effects of the most promising prosapogenin mixture from alfalfa tops were confirmed by means of in planta tests using three different Italian cultivars of rice (Oryza sativa L. ssp. japonica), known to possess high, medium, and low blast resistance. The evidenced antifungal properties of the tested metabolites allowed some considerations on their structure-activity relationship. Results indicate that prosapogenins are active compounds to prevent the fungal attack of P. oryzae on different rice cultivars. Therefore, if properly formulated, these substances could represent a promising and environmentally friendly treatment to control rice blast. PMID:25361378

Abbruscato, Pamela; Tosi, Solveig; Crispino, Laura; Biazzi, Elisa; Menin, Barbara; Picco, Anna M; Pecetti, Luciano; Avato, Pinarosa; Tava, Aldo

2014-11-19

394

Inhibition of catechol-o-methyltransferase (COMT) by myricetin, dihydromyricetin, and myricitrin.  

PubMed

Catechol O-methyltransferase (COMT) is an important enzyme involved in the metabolism of levodopa (L-dopa) which is clinically used to treat Parkinson's disease through boosting the concentration of dopamine in the brain. Development of COMT inhibitors can efficiently increase the bioavailability of L-dopa. The present study aims to evaluate the inhibition of COMT activity by three herbal components isolated from Myrica rubra Sieb. et Zucc.. The in vitro human liver cytosol-catalyzed L-dopa methylation reaction was utilized. The results showed that all these three compounds strongly inhibited COMT activity in a concentration-dependent manner. The inhibition was competitive for these three compounds, as demonstrated by Dixon and Lineweaver-Burk plots. The inhibition kinetic parameters (Ki) towards COMT activity were calculated to be 0.5, 0.2, and 0.9 microM for myricitrin, myricetin, and dihydromyricetin, respectively. From the view of structures, the deglycosylation biotransformation of myricitrin into myricetin can increase the inhibitory ability towards COMT. However, further structural alteration of myricetin towards dihydromyricetin weakens the inhibitory potential towards COMT. PMID:24716406

Zhu, Xu; Jia, Yun-Hong

2014-03-01

395

Schistosome and liver fluke derived catechol-estrogens and helminth associated cancers.  

PubMed

Infection with helminth parasites remains a persistent public health problem in developing countries. Three of these pathogens, the liver flukes Clonorchis sinensis, Opisthorchis viverrini and the blood fluke Schistosoma haematobium, are of particular concern due to their classification as Group 1 carcinogens: infection with these worms is carcinogenic. Using liquid chromatography-mass spectrometry (LC-MS/MS) approaches, we identified steroid hormone like (e.g., oxysterol-like, catechol estrogen quinone-like, etc.) metabolites and related DNA-adducts, apparently of parasite origin, in developmental stages including eggs of S. haematobium, in urine of people with urogenital schistosomiasis, and in the adult stage of O. viverrini. Since these kinds of sterol derivatives are metabolized to active quinones that can modify DNA, which in other contexts can lead to breast and other cancers, helminth parasite associated sterols might induce tumor-like phenotypes in the target cells susceptible to helminth parasite associated cancers, i.e., urothelial cells of the bladder in the case of urogenital schistosomiasis and the bile duct epithelia or cholangiocytes, in the case of O. viverrini and C. sinensis. Indeed we postulate that helminth induced cancers originate from parasite estrogen-host epithelial/urothelial cell chromosomal DNA adducts, and here we review recent findings that support this conjecture. PMID:25566326

Correia da Costa, José M; Vale, Nuno; Gouveia, Maria J; Botelho, Mónica C; Sripa, Banchob; Santos, Lúcio L; Santos, Júlio H; Rinaldi, Gabriel; Brindley, Paul J

2014-01-01

396

Characterization of Non-Nitrocatechol Pan and Isoform Specific Catechol-O-methyltransferase Inhibitors and Substrates  

PubMed Central

Reduced dopamine neurotransmission in the prefrontal cortex has been implicated as causal for the negative symptoms and cognitive deficit associated with schizophrenia; thus, a compound which selectively enhances dopamine neurotransmission in the prefrontal cortex may have therapeutic potential. Inhibition of catechol-O-methyltransferase (COMT, EC 2.1.1.6) offers a unique advantage, since this enzyme is the primary mechanism for the elimination of dopamine in cortical areas. Since membrane bound COMT (MB-COMT) is the predominant isoform in human brain, a high throughput screen (HTS) to identify novel MB-COMT specific inhibitors was completed. Subsequent optimization led to the identification of novel, non-nitrocatechol COMT inhibitors, some of which interact specifically with MB-COMT. Compounds were characterized for in vitro efficacy versus human and rat MB and soluble (S)-COMT. Select compounds were administered to male Wistar rats, and ex vivo COMT activity, compound levels in plasma and cerebrospinal fluid (CSF), and CSF dopamine metabolite levels were determined as measures of preclinical efficacy. Finally, novel non-nitrocatechol COMT inhibitors displayed less potent uncoupling of the mitochondrial membrane potential (MMP) compared to tolcapone as well as nonhepatotoxic entacapone, thus mitigating the risk of hepatotoxicity. PMID:22860182

2011-01-01

397

Synthesis, Characterization, and Preliminary Investigation of Cell Interaction of Magnetic Nanoparticles with Catechol-Containing Shells  

SciTech Connect

Superparamagnetic iron oxide cores were synthesized by co-precipitation of Fe(II) and Fe(III) salts and subsequently stabilized by coating with different catechols (levodopa, dopamine, hydrocaffeic acid, dopamine-containing carboxymethyl dextran) known to act as high-affinity, bidentate ligands for Fe(III). The prepared stable magnetic fluids were characterized with regard to their chemical composition (content of iron and shell material, Fe(II)/Fe(III) ratio) and their physical properties (size, surface charge, magnetic parameters). The nanoparticles showed no or only slight cytotoxic effects within 1 and 4 days of incubation with 3T3 fibroblast cells. Preliminary experiments were performed to study the interaction of the prepared nanoparticles with human MCF-7 breast cancer cells and leukocytes. An intense interaction of the MCF-7 cells with these particles was found whereas the leukocytes showed a lower tendency of interaction. Based on these finding, the novel magnetic nanoparticles possess the potential for use in depletion of tumor cells from peripheral blood.

Wagner, Kerstin; Seemann, Thomas; Wyrwa, Ralf; Schnabelrauch, Matthias [Biomaterials Department, INNOVENT e. V., Pruessingstrasse 27 B, D-07745 Jena (Germany); Clement, Joachim H. [Department of Internal Medicine II, University Hospital Jena, Erlanger Allee 101, D-07740 Jena (Germany); Mueller, Robert [Institute of Photonic Technology, Albert-Einstein-Strasse 9, D-07745 Jena (Germany); Nietzsche, Sandor [Center for Electron Microscopy, University Hospital Jena, Ziegelmuehlenweg 1, D-07743 Jena (Germany)

2010-12-02

398

Catechol-O-Methyltransferase Val158Met Polymorphism Is Associated with Somatosensory Amplification and Nocebo Responses  

PubMed Central

A large number of unwanted adverse events and symptoms reported by patients in clinical trials are not caused by the drug provided, since most of adverse events also occur in corresponding placebo groups. These nocebo effects also play a major role in drug discontinuation in clinical practice, negatively affecting treatment efficacy as well as patient adherence and compliance. Experimental and clinical data document a large interindividual variability in nocebo responses, however, data on psychological, biological or genetic predictors of nocebo responses are lacking. Thus, with an established paradigm of behaviorally conditioned immunosuppressive effects we analyzed possible genetic predictors for nocebo responses. We focused on the genetic polymorphisms in the catechol-O-methyltransferase (COMT) gene (Val158Met) and analyzed drug specific and general side effects before and after immunosuppressive medication and subsequent placebo intake in 62 healthy male subjects. Significantly more drug-specific as well as general side effects were reported from homozygous carriers of the Val158 variant during medication as well as placebo treatment compared to the other genotype groups. Val158/Val158 carriers also had significantly higher scores in the somatosensory amplification scale (SSAS) and the BMQ (beliefs about medicine questionnaire). Together these data demonstrate potential genetic and psychological variables predicting nocebo responses after drug and placebo intake, which might be utilized to minimize nocebo effects in clinical trials and medical practice. PMID:25222607

Benson, Sven; Engler, Harald; Engler, Andrea; Hinney, Anke; Rief, Winfried; Witzke, Oliver; Schedlowski, Manfred

2014-01-01

399

[Kinetic analysis of laccase catalyze phenolic and aniline compounds and detecting catechol in wastewater].  

PubMed

Phenolic or aniline compounds were important pollutants in the industrial wastewaters to seriously polluted water environment. This research developed a detecting method of phenolic and aniline compounds based on the kinetic parameters of the substrates of laccase. Catalytic reaction between laccase and phenolic and aniline compounds was characterized using spectrophotometic method, which resulted 0-10 mg/L substrate reaction rate and calibration curve of substrate concentration and reaction rate. And then the non-volatile phenols in three kinds of coking wastewater were screened and the contents were detected. The result showed that polyhydric phenol, multi-amine and aminophenol were the main substrates of laccase. The optimum pH of phenols was around 7.0 and anilines 4.5-5.0, K(m) values of each substrates was 0.4-10 mmol/L. The calibration curve performed good first order kinetics linear relationship except benzidine with correlation coefficients above 0.96. Using laccase method, the contents of catechol in three kinds of coking wastewater were respectively detected to be 190.5, 265.8 and 155.3 mg/L with recoveries ranged from 89.9% to 115.8%. PMID:21250450

Zhong, Ping-Fang; Peng, Hui-Min; Peng, Fang-Yi; Cai, Qiang; He, Miao

2010-11-01

400

Laccase Biosensor Based on Electrospun Copper/Carbon Composite Nanofibers for Catechol Detection  

PubMed Central

The study compared the biosensing properties of laccase biosensors based on carbon nanofibers (CNFs) and copper/carbon composite nanofibers (Cu/CNFs). The two kinds of nanofibers were prepared by electrospinning and carbonization under the same conditions. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy were employed to investigate the morphologies and structures of CNFs and Cu/CNFs. The amperometric results indicated that the Cu/CNFs/laccase(Lac)/Nafion/glass carbon electrode (GCE) possessed reliable analytical performance for the detection of catechol. The sensitivity of the Cu/CNFs/Lac/Nafion/GCE reached 33.1 ?A/mM, larger than that of CNFs/Lac/Nafion/GCE. Meanwhile, Cu/CNFs/Lac/Nafion/GCE had a wider linear range from 9.95 × 10?6 to 9.76 × 10?3 M and a lower detection limit of 1.18 ?M than CNFs/Lac/Nafion/GCE. Moreover, it exhibited a good repeatability, reproducibility, selectivity and long-term stability, revealing that electrospun Cu/CNFs have great potential in biosensing. PMID:24561403

Fu, Jiapeng; Qiao, Hui; Li, Dawei; Luo, Lei; Chen, Ke; Wei, Qufu

2014-01-01

401

Synthesis and biological activity of 2-carbomethoxy-3-catechol-8-azabicyclo[3.2.1]octanes.  

PubMed

Cocaine inhibits the dopamine transporter and the consequent elevation of dopamine is thought to contribute to the addictive properties of cocaine. Tropane analogues of cocaine, targeted to the dopamine transporter (DAT), are a significant focus of drug design for cocaine addiction medications. Herein, we report the function of the ortho hydroxy substituents in dopamine with respect to the azabicyclo[3.2.1]octane skeleton. The introduction of the o-dihydroxyl functionality led to reduced binding potency at monoamine transporters, rather than enhanced interaction with the DAT. It is therefore likely that the binding site for these compounds on the DAT is not the same as that for dopamine. Notwithstanding the moderate potency of the free catechols (>100 nM), 7 manifested stimulant activity with a duration of effect that exceeded 4 h in a rat locomotor activity assay. Compound 10, a diacetoxy prodrug for 7, substituted fully for cocaine in a rat drug-discrimination paradigm and is now undergoing further investigation as a potential medication for cocaine abuse. PMID:14592523

Meltzer, Peter C; McPhee, Mark; Madras, Bertha K

2003-11-17

402

Synthesis, Characterization, and Preliminary Investigation of Cell Interaction of Magnetic Nanoparticles with Catechol-Containing Shells  

NASA Astrophysics Data System (ADS)

Superparamagnetic iron oxide cores were synthesized by co-precipitation of Fe(II) and Fe(III) salts and subsequently stabilized by coating with different catechols (levodopa, dopamine, hydrocaffeic acid, dopamine-containing carboxymethyl dextran) known to act as high-affinity, bidentate ligands for Fe(III). The prepared stable magnetic fluids were characterized with regard to their chemical composition (content of iron and shell material, Fe(II)/Fe(III) ratio) and their physical properties (size, surface charge, magnetic parameters). The nanoparticles showed no or only slight cytotoxic effects within 1 and 4 days of incubation with 3T3 fibroblast cells. Preliminary experiments were performed to study the interaction of the prepared nanoparticles with human MCF-7 breast cancer cells and leukocytes. An intense interaction of the MCF-7 cells with these particles was found whereas the leukocytes showed a lower tendency of interaction. Based on these finding, the novel magnetic nanoparticles possess the potential for use in depletion of tumor cells from peripheral blood.

Wagner, Kerstin; Seemann, Thomas; Wyrwa, Ralf; Clement, Joachim H.; Müller, Robert; Nietzsche, Sandor; Schnabelrauch, Matthias

2010-12-01

403

Formation of dibenzofuran, dibenzo-p-dioxin and their hydroxylated derivatives from catechol.  

PubMed

We present, in this study, mechanistic and kinetic accounts of the formation of dibenzofuran (DF), dibenzo-p-dioxin (DD) and their hydroxylated derivatives (OHs-DF/OHs-DD) from the catechol (CT) molecule, as a model compound for phenolic constituents in biomass. Self-condensation of two CT molecules produces predominantly a DD molecule via open- and closed-shell corridors. Coupling modes involving the o-semiquinone radical and the CT molecule (o-SQ/CT) generate two direct structural blocks for the formation of OHs-DF/OHs-DD structures, ether-type intermediates and di-keto moieties. The calculated reaction rate constants indicate that the fate of ether-type intermediates is to make hydroxylated diphenyl ethers rather than to undergo cyclisation reactions leading to the formation of preDF structures. Unimolecular loss of a H or OH moiety from a pivotal carbon in these hydroxylated diphenyl ethers then produces hydroxylated and non-hydroxylated DD molecules. Formation of OHs-DF initiated by o(C)-o(C) cross-linkages involving o-SQ/o-SQ and o-SQ/CT reactions incurs very similar reaction and activation enthalpies encountered in the formation of chlorinated DFs from chlorophenols. PMID:25474266

Altarawneh, Mohammednoor; Dlugogorski, Bogdan Z

2015-01-21

404

Association between catechol-O-methyltransferase Val(158)Met polymorphism and configural mode of face processing.  

PubMed

Human visual system heavily relies on the spatial configuration among facial parts in discriminating faces. There are individual differences in the ability of configural face processing, which are supposed to be partly attributable to genetic predispositions. However, few studies have identified a specific gene linked to configural face processing ability. The present study investigated an association between configural mode of face processing and a single-nucleotide polymorphism in codon 158 of catechol-O-methyltransferase gene (COMT Val(158)Met polymorphism) using part-spacing paradigm. The results have revealed superior sensitivity to the changes in facial configuration in participants with Met/Met genotype of COMT Val(158)Met polymorphism compared to the other genotypes. This effect was virtually eliminated when the faces were presented upside-down. There was no group-difference in the ability to detect the change in morphological features of individual facial parts. These results indicate that COMT Val(158)Met polymorphism partly explains the individual differences in the ability of configural face processing. PMID:25481766

Doi, Hirokazu; Nishitani, Shota; Shinohara, Kazuyuki

2015-01-23

405

Schistosome and liver fluke derived catechol-estrogens and helminth associated cancers  

PubMed Central

Infection with helminth parasites remains a persistent public health problem in developing countries. Three of these pathogens, the liver flukes Clonorchis sinensis, Opisthorchis viverrini and the blood fluke Schistosoma haematobium, are of particular concern due to their classification as Group 1 carcinogens: infection with these worms is carcinogenic. Using liquid chromatography-mass spectrometry (LC-MS/MS) approaches, we identified steroid hormone like (e.g., oxysterol-like, catechol estrogen quinone-like, etc.) metabolites and related DNA-adducts, apparently of parasite origin, in developmental stages including eggs of S. haematobium, in urine of people with urogenital schistosomiasis, and in the adult stage of O. viverrini. Since these kinds of sterol derivatives are metabolized to active quinones that can modify DNA, which in other contexts can lead to breast and other cancers, helminth parasite associated sterols might induce tumor-like phenotypes in the target cells susceptible to helminth parasite associated cancers, i.e., urothelial cells of the bladder in the case of urogenital schistosomiasis and the bile duct epithelia or cholangiocytes, in the case of O. viverrini and C. sinensis. Indeed we postulate that helminth induced cancers originate from parasite estrogen-host epithelial/urothelial cell chromosomal DNA adducts, and here we review recent findings that support this conjecture. PMID:25566326

Correia da Costa, José M.; Vale, Nuno; Gouveia, Maria J.; Botelho, Mónica C.; Sripa, Banchob; Santos, Lúcio L.; Santos, Júlio H.; Rinaldi, Gabriel; Brindley, Paul J.

2014-01-01

406

Disruptive mRNA folding increases translational efficiency of catechol-O-methyltransferase variant  

PubMed Central

Catechol-O-methyltransferase (COMT) is a major enzyme controlling catecholamine levels that plays a central role in cognition, affective mood and pain perception. There are three common COMT haplotypes in the human population reported to have functional effects, divergent in two synonymous and one nonsynonymous position. We demonstrate that one of the haplotypes, carrying the non-synonymous variation known to code for a less stable protein, exhibits increased protein expression in vitro. This increased protein expression, which would compensate for lower protein stability, is solely produced by a synonymous variation (C166T) situated within the haplotype and located in the 5? region of the RNA transcript. Based on mRNA secondary structure predictions, we suggest that structural destabilization near the start codon caused by the T allele could be related to the observed increase in COMT expression. Our folding simulations of the tertiary mRNA structures demonstrate that destabilization by the T allele lowers the folding transition barrier, thus decreasing the probability of occupying its native state. These data suggest a novel structural mechanism whereby functional synonymous variations near the translation initiation codon affect the translation efficiency via entropy-driven changes in mRNA dynamics and present another example of stable compensatory genetic variations in the human population. PMID:21486747

Tsao, Douglas; Shabalina, Svetlana A.; Gauthier, Josée; Dokholyan, Nikolay V.; Diatchenko, Luda

2011-01-01

407

Colloidal stability of iron oxide nanocrystals coated with a PEG-based tetra-catechol surfactant  

NASA Astrophysics Data System (ADS)

Long-term colloidal stability of magnetic iron oxide nanoparticles (NPs) is an important goal that has not yet been fully achieved. To make an advance in our understanding of the colloidal stability of iron oxide NPs in aqueous media, we prepared NPs comprising a monodisperse (13 nm) iron oxide core coated with a PEG-based (PEG: polyethyleneglycol) surfactant. This consists of a methoxy-terminated PEG chain (MW = 5000 Da) bearing four catechol groups via a diethylenetriamine linker. The surfactant was grafted onto the nanocrystals by ligand exchange monitored by infrared spectroscopy. The colloidal stability of these nanoparticles was probed by monitoring the time evolution of the Z-average intensity-weighted radius Rh and volume-weighted size distribution Pv obtained from analysis of dynamic light scattering data. The nanoparticles showed no sign of aggregation for four months in deionized water at room temperature and also when subjected to thermal cycling between 25 and 75?°C. In 0.01 M PBS (phosphate buffered saline), aggregation (if any) is slow and partial; after 66 h, about 50% of NPs have not aggregated. Aggregation is more effective in 0.15 M NH4AcO buffer, where isolated particles are not observed after 66 h, and especially in acidic NH4AcO/AcOH buffer, where aggregation is complete within 1 h and precipitation is observed. The differing stability of the NPs in the above aqueous media is closely related to their ? potential.

Mondini, Sara; Drago, Carmelo; Ferretti, Anna M.; Puglisi, Alessandra; Ponti, Alessandro

2013-03-01

408

Analysis of Oxidative Stress Status, Catalase and Catechol-O-Methyltransferase Polymorphisms in Egyptian Vitiligo Patients  

PubMed Central

Vitiligo is the most common depigmentation disorder of the skin. Oxidative stress is implicated as one of the probable events involved in vitiligo pathogenesis possibly contributing to melanocyte destruction. Evidence indicates that certain genes including those involved in oxidative stress and melanin synthesis are crucial for development of vitiligo. This study evaluates the oxidative stress status, the role of catalase (CAT) and catechol-O-Methyltransferase (COMT) gene polymorphisms in the etiology of generalized vitiligo in Egyptians. Total antioxidant capacity (TAC) and malondialdehyde (MDA) levels as well as CAT exon 9 T/C and COMT 158 G/A polymorphisms were determined in 89 patients and 90 age and sex-matched controls. Our results showed significantly lower TAC along with higher MDA levels in vitiligo patients compared with controls. Meanwhile, genotype and allele distributions of CAT and COMT polymorphisms in cases were not significantly different from those of controls. Moreover, we found no association between both polymorphisms and vitiligo susceptibility. In conclusion, the enhanced oxidative stress with the lack of association between CAT and COMT polymorphisms and susceptibility to vitiligo in our patients suggest that mutations in other genes related to the oxidative pathway might contribute to the etiology of generalized vitiligo in Egyptian population. PMID:24915010

Mehaney, Dina A.; Darwish, Hebatallah A.; Hegazy, Rehab A.; Nooh, Mohammed M.; Tawdy, Amira M.; Gawdat, Heba I.; El-Sawalhi, Maha M.

2014-01-01

409

Catechol--an oviposition stimulant for cigarette beetle in roasted coffee beans.  

PubMed

The cigarette beetle, Lasioderma serricorne, is a serious global pest that preys on stored food products. Larvae of the beetle cannot grow on roasted coffee beans or dried black or green tea leaves, although they oviposit on such products. We investigated oviposition by the beetles on MeOH extracts of the above products. The number of eggs laid increased with an increase in dose of each extract, indicating that chemical factors stimulate oviposition by the beetles. This was especially true for \\ coffee bean extracts, which elicited high numbers of eggs even at a low dose (0.1 g bean equivalent/ml) compared to other extracts. Coffee beans were extracted in hexane, chloroform, 1-butanol, MeOH, and 20% MeOH in water. The number of eggs laid was higher on filter papers treated with chloroform, 1-butanol, MeOH, and 20% MeOH in water extracts than on control (solvent alone) papers. The chloroform extract was fractionated by silica-gel column chromatography. Nine compounds were identified by gas chromatography/mass spectrometry from an active fraction. Of these compounds, only a significant ovipositional response to catechol was observed. PMID:24752858

Nagasawa, Atsuhiko; Kamada, Yuji; Kosaka, Yuji; Arakida, Naohiro; Hori, Masatoshi

2014-05-01

410

A Novel Class of Gibberellin 2-Oxidases Control Semidwarfism, Tillering, and Root Development in Rice[W  

PubMed Central

Gibberellin 2-oxidases (GA2oxs) regulate plant growth by inactivating endogenous bioactive gibberellins (GAs). Two classes of GA2oxs inactivate GAs through 2?-hydroxylation: a larger class of C19 GA2oxs and a smaller class of C20 GA2oxs. In this study, we show that members of the rice (Oryza sativa) GA2ox family are differentially regulated and act in concert or individually to control GA levels during flowering, tillering, and seed germination. Using mutant and transgenic analysis, C20 GA2oxs were shown to play pleiotropic roles regulating rice growth and architecture. In particular, rice overexpressing these GA2oxs exhibited early and increased tillering and adventitious root growth. GA negatively regulated expression of two transcription factors, O. sativa homeobox 1 and TEOSINTE BRANCHED1, which control meristem initiation and axillary bud outgrowth, respectively, and that in turn inhibited tillering. One of three conserved motifs unique to the C20 GA2oxs (motif III) was found to be important for activity of these GA2oxs. Moreover, C20 GA2oxs were found to cause less severe GA-defective phenotypes than C19 GA2oxs. Our studies demonstrate that improvements in plant architecture, such as semidwarfism, increased root systems and higher tiller numbers, could be induced by overexpression of wild-type or modified C20 GA2oxs. PMID:18952778

Lo, Shuen-Fang; Yang, Show-Ya; Chen, Ku-Ting; Hsing, Yue-Ie; Zeevaart, Jan A.D.; Chen, Liang-Jwu; Yu, Su-May

2008-01-01

411

Kernel infection of Bluebonnet 50 rice by Helminthosporium oryzae and its effect on yield and quality  

E-print Network

KERNEL INFECTION OF BLUEBONNET 50 RICE BY HELMINTHOSPORIUM ORYZAE AND ITS EFFECT ON YIELD AND QUALITY A Thesis By SYED FAZAL IMAM FAZLI Submitted to the Graduate College of the Texas A8cM University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE January 1964 MaJor SubJect: Plant Pathology KERNEL INFECTION OF BLUEBONNET 50 RICE BY HELMINTHOSPORIUM ORYZAE AND ITS EFFECT ON YIELD AND QUALITY A Thesis By SYED IAZAL IMAM FAZLI Approved as to style and content by...

Fazli, Syed Fazal Imam

2012-06-07

412

Identification of Topaquinone, As Illustrated for Pig Kidney Diamine Oxidase and Escherichia coli Amine Oxidase  

Microsoft Academic Search

Pig kidney diamine oxidase was purified to homogeneity. The reaction product of the cofactor with p-nitrophenylhydrazine (pNPH) was liberated with pronase treatment and purified. 1H NMR, uv\\/vis, and electrospray tandem mass spectroscopy revealed it to be a dipeptide with the sequence topaquinone-pNPH and aspartate. No heterogeneity was observed, indicating that no intramolecular cyclization of the quinone moiety occurs in the

V. Steinebach; B. W. Groen; S. S. Wijmenga; W. M. A. Niessen; J. A. Jongejan; J. A. Duine

1995-01-01

413

Dephenolization of industrial wastewaters catalyzed by polyphenol oxidase  

SciTech Connect

A new enzymatic method for the removal of phenols from industrial aqueous effluents has been developed. The method uses the enzyme polyphenol oxidase which oxidizes phenols to the corresponding o-quinones; the latter then undergo a nonenzymatic polymerization to form water-insoluble aggregates. Therefore, the enzyme in effect precipitates phenols from water. Polyphenol oxidase has been found to nearly completely dephenolize solutions of phenol in the concentration range from 0.01 to 1.0 g/L. The enzymatic treatment is effective over a wide range of pH and temperature; a crude preparation of polyphenol oxidase (mushroom extract) is as effective as a purified, commercially obtained version. In addition to phenol itself, polyphenol oxidase is capable of precipitating from water a number of substituted phenols (cresols, chlorophenols, naphthol, etc.). Also, even pollutants which are unreactive towards polyphenol oxidase can be enzymatically coprecipitated with phenol. The polyphenol oxidase treatment has been successfully used to dephenolize two different real industrial wastewater samples, from a plant producing triarylphosphates and from a coke plant. The advantage of the polyphenol oxidase dephenolization over the peroxidase-catalyzed one previously elaborated by the authors is that the former enzyme uses molecular oxygen instead of costly hydrogen peroxide (used by peroxidase) as an oxidant.

Atlow, S.C.; Bonadonna-Aparo, L.; Klibanov, A.M.

1984-01-01

414

The structure and inhibition of human diamine oxidase†,‡  

PubMed Central

Humans have three functioning genes that code for copper-containing amine oxidases. The product of the AOC1 gene is a so-called diamine oxidase (hDAO), named for its substrate preference for diamines, particularly histamine. hDAO has been cloned and expressed in insect cells and the structure of the native enzyme determined by X-ray crystallography to a resolution of 1.8 Ĺ. The homodimeric structure has the archetypal amine oxidase fold. Two active sites, one in each subunit, are characterized by the presence of a copper ion and a topaquinone residue formed by the post-translational modification of a tyrosine. Although hDAO shares 37.9 % sequence identity with another human copper amine oxidase, semicarbazide sensitive amine oxidase or vascular adhesion protein-1, its substrate binding pocket and entry channel are distinctly different in accord with the different substrate specificities. The structures of two inhibitor complexes of hDAO, berenil and pentamidine, have been refined to resolutions of 2.1 Ĺ and 2.2 Ĺ, respectively. They bind non-covalently in the active site channel. The inhibitor binding suggests that an aspartic acid residue, conserved in all diamine oxidases but absent from other amine oxidases, is responsible for the diamine specificity by interacting with the second amino group of preferred diamine substrates. PMID:19764817

McGrath, Aaron P; Hilmer, Kimberly M; Collyer, Charles A; Shepard, Eric M; Elmore, Bradley O.; Brown, Doreen E; Dooley, David M; Guss, J Mitchell

2009-01-01

415

Evaluation of oxalate decarboxylase and oxalate oxidase for industrial applications.  

PubMed

Increased recirculation of process water has given rise to problems with formation of calcium oxalate incrusts (scaling) in the pulp and paper industry and in forest biorefineries. The potential in using oxalate decarboxylase from Aspergillus niger for oxalic acid removal in industrial bleaching plant filtrates containing oxalic acid was examined and compared with barley oxalate oxidase. Ten different filtrates from chemical pulping were selected for the evaluation. Oxalate decarboxylase degraded oxalic acid faster than oxalate oxidase in eight of the filtrates, while oxalate oxidase performed better in one filtrate. One of the filtrates inhibited both enzymes. The potential inhibitory effect of selected compounds on the enzymatic activity was tested. Oxalate decarboxylase was more sensitive than oxalate oxidase to hydrogen peroxide. Oxalate decarboxylase was not as sensitive to chlorate and chlorite as oxalate oxidase. Up to 4 mM chlorate ions, the highest concentration tested, had no inhibitory effect on oxalate decarboxylase. Analysis of the filtrates suggests that high concentrations of chlorate present in some of the filtrates were responsible for the higher sensitivity of oxalate oxidase in these filtrates. Oxalate decarboxylase was thus a better choice than oxalate oxidase for treatment of filtrates from chlorine dioxide bleaching. PMID:19763895

Cassland, Pierre; Sjöde, Anders; Winestrand, Sandra; Jönsson, Leif J; Nilvebrant, Nils-Olof

2010-05-01

416

Early alterations of rat intestinal diamine oxidase activity by azoxymethane, an intestinal carcinogen  

Microsoft Academic Search

Some mutagenic hydrazino compounds are also diamine oxidase inhibitors. Therefore, this interrelationship was studied for the intestinal carcinogen azoxymethane.In vitro, azoxymethane was a very weak inhibitor of rat intestinal diamine oxidase activity.In vivo, after subcutaneous injection of a single dose of azoxymethane, diamine oxidase activity was increased in the duodenum but was mainly inhibited in the colon. Intestinal diamine oxidase

J. Kusche; R. Mennigen; L. Leisten

1989-01-01

417

Small brown planthopper resistance loci in wild rice (Oryza officinalis).  

PubMed

Host-plant resistance is the most practical and economical approach to control the rice planthoppers. However, up to date, few rice germplasm accessions that are resistant to the all three kinds of planthoppers (1) brown planthopper (BPH; Nilaparvata lugens Stĺl), (2) the small brown planthopper (SBPH; Laodelphax striatellus Fallen), and (3) the whitebacked planthopper (WBPH, Sogatella furcifera Horvath) have been identified; consequently, the genetic basis for host-plant broad spectrum resistance to rice planthoppers in a single variety has been seldom studied. Here, one wild species, Oryza officinalis (Acc. HY018, 2n = 24, CC), was detected showing resistance to the all three kinds of planthoppers. Because resistance to WBPH and BPH in O. officinalis has previously been reported, the study mainly focused on its SBPH resistance. The SBPH resistance gene(s) was (were) introduced into cultivated rice via asymmetric somatic hybridization. Three QTLs for SBPH resistance detected by the SSST method were mapped and confirmed on chromosomes 3, 7, and 12, respectively. The allelic/non-allelic relationship and relative map positions of the three kinds of planthopper resistance genes in O. officinalis show that the SBPH, WBPH, and BPH resistance genes in O. officinalis were governed by multiple genes, but not by any major gene. The data on the genetics of host-plant broad spectrum resistance to planthoppers in a single accession suggested that the most ideally practical and economical approach for rice breeders is to screen the sources of broad spectrum resistance to planthoppers, but not to employ broad spectrum resistance gene for the management of planthoppers. Pyramiding these genes in a variety can be an effective way for the management of planthoppers. PMID:24504629

Zhang, Weilin; Dong, Yan; Yang, Ling; Ma, Bojun; Ma, Rongrong; Huang, Fudeng; Wang, Changchun; Hu, Haitao; Li, Chunshou; Yan, Chengqi; Chen, Jianping

2014-06-01

418

Direct regulation of cytochrome c oxidase by calcium ions.  

PubMed

Cytochrome c oxidase from bovine heart binds Ca(2+) reversibly at a specific Cation Binding Site located near the outer face of the mitochondrial membrane. Ca(2+) shifts the absorption spectrum of heme a, which allowed previously to determine the kinetics and equilibrium characteristics of the binding. However, no effect of Ca(2+) on the functional characteristics of cytochrome oxidase was revealed earlier. Here we report that Ca(2+) inhibits cytochrome oxidase activity of isolated bovine heart enzyme by 50-60% with Ki of ?1 ľM, close to Kd of calcium binding with the oxidase determined spectrophotometrically. The inhibition is observed only at low, but physiologically relevant, turnover rates of the enzyme (?10 s(-1) or less). No inhibitory effect of Ca(2+) is observed under conventional conditions of cytochrome c oxidase activity assays (turnover number >100 s(-1) at pH 8), which may explain why the effect was not noticed earlier. The inhibition is specific for Ca(2+) and is reversed by EGTA. Na(+) ions that compete with Ca(2+) for binding with the Cation Binding Site, do not affect significantly activity of the enzyme but counteract the inhibitory effect of Ca(2+). The Ca(2+)-induced inhibition of cytochrome c oxidase is observed also with the uncoupled mitochondria from several rat tissues. At the same time, calcium ions do not inhibit activity of the homologous bacterial cytochrome oxidases. Possible mechanisms of the inhibition are discussed as well as potential physiological role of Ca(2+) binding with cytochrome oxidase. Ca(2+)- binding at the Cation Binding Site is proposed to inhibit proton-transfer through the exit part of the proton conducting pathway H in the mammalian oxidases. PMID:24058566

Vygodina, Tatiana; Kirichenko, Anna; Konstantinov, Alexander A

2013-01-01

419

Comparison of the genomes and transcriptomes associated with the different protease secretions of Aspergillus oryzae 100-8 and 3.042.  

PubMed

Aspergillus oryzae is used to produce traditional fermented foods and beverages. A. oryzae 3.042 produces a neutral protease and an alkaline protease but rarely an acid protease, which is unfavourable to soy-sauce fermentation. A. oryzae 100-8 was obtained by N(+) ion implantation mutagenesis of A. oryzae 3.042, and the protease secretions of these two strains are different. Sequencing the genome of A. oryzae 100-8 and comparing it to the genomes of A. oryzae 100-8 and 3.042 revealed some differences, such as single nucleotide polymorphisms, nucleotide deletion or insertion. Some of these differences may reflect the ability of A. oryzae to secrete proteases. Transcriptional sequencing and analysis of the two strains during the same growth processes provided further insights into the genes and pathways involved in protease secretion. PMID:25048221

Zhao, Guozhong; Yao, Yunping; Hou, Lihua; Wang, Chunling; Cao, Xiaohong

2014-10-01

420

Visualization of monoamine oxidase in human brain  

SciTech Connect

Monoamine oxidase is a flavin enzyme which exists in two subtypes, MAO A and MAO B. In human brain MAO B predominates and is largely compartmentalized in cell bodies of serotonergic neurons and glia. Regional distribution of MAO B was determined by positron computed tomography with volunteers after the administration of deuterium substituted [11C]L-deprenyl. The basal ganglia and thalamus exhibited the greatest concentrations of MAO B with intermediate levels in the frontal cortex and cingulate gyrus while lowest levels were observed in the parietal and temporal cortices and cerebellum. We observed that brain MAO B increases with are in health normal subjects, however the increases were generally smaller than those revealed with post-mortem studies.

Fowler, J.S.; Volkow, N.D.; Wang, G.J.; Pappas, N.; Shea, C.; MacGregor, R.R.; Logan, J.

1996-12-31

421

A fundamental understanding of catechol and water adsorption on a hydrophilic silica surface: exploring the underwater adhesion mechanism of mussels on an atomic scale.  

PubMed

Mussels have a remarkable ability to bond to solid surfaces under water. From a microscopic perspective, the first step of this process is the adsorption of dopa molecules to the solid surface. In fact, it is the catechol part of the dopa molecule that is interacting with the surface. These molecules are able to make reversible bonds to a wide range of materials, even underwater. Previous experimental and theoretical efforts have produced only a limited understanding of the mechanism and quantitative details of the competitive adsorption of catechol and water on hydrophilic silica surfaces. In this work, we uncover the nature of this competitive absorption by atomic scale modeling of water and catechol adsorbed at the geminal (001) silica surface using density functional theory calculations. We find that catechol molecules displace preadsorbed water molecules and bond directly on the silica surface. Using molecular dynamics simulations, we observe this process in detail. We also calculate the interaction force as a function of distance, and observe a maximum of 0.5 nN of attraction. The catechol has a binding energy of 23 kcal/mol onto the silica surface with adsorbed water molecules. PMID:24835420

Mian, Shabeer Ahmad; Yang, Li-Ming; Saha, Leton Chandra; Ahmed, E; Ajmal, Muhammad; Ganz, Eric

2014-06-17

422

[A method of determining glucose oxidase-immobilized glucose].  

PubMed

A method for manual measurement of glucose in biologic fluids has been developed, making use of glucose oxidase immobilized on a carbamide derivative of microcrystal cellulose; two variants are suggested: a rapid and a routine one. The method is characterized by a high analytical reliability, its results are in high correlation with the results of measurements by Beckman glucose analyzer (r = 0.92, p less than 0.001). The method is economic (glucose oxidase reagent may be used for more than 300 times), easily available, and is 3 to 6 times more rapid than the method with soluble glucose oxidase. It is particularly convenient for urgent laboratory diagnosis. PMID:1722525

Ivanov, I P; Danev, S I; Dimitrov, D G

1991-01-01

423

Multilayered Polyelectrolyte Microcapsules: Interaction with the Enzyme Cytochrome C Oxidase  

PubMed Central

Cell-sized polyelectrolyte capsules functionalized with a redox-driven proton pump protein were assembled for the first time. The interaction of polyelectrolyte microcapsules, fabricated by electrostatic layer-by-layer assembly, with cytochrome c oxidase molecules was investigated. We found that the cytochrome c oxidase retained its functionality, that the functionalized microcapsules interacting with cytochrome c oxidase were permeable and that the permeability characteristics of the microcapsule shell depend on the shell components. This work provides a significant input towards the fabrication of an integrated device made of biological components and based on specific biomolecular functions and properties. PMID:25372607

Pastorino, Laura; Dellacasa, Elena; Noor, Mohamed R.; Soulimane, Tewfik; Bianchini, Paolo; D'Autilia, Francesca; Antipov, Alexei; Diaspro, Alberto; Tofail, Syed A. M.; Ruggiero, Carmelina

2014-01-01

424

Effect of feeding Aspergillus oryzae fermentation extract or Aspergillus oryzae plus yeast culture plus mineral and vitamin supplement on performance of Holstein cows during a complete lactation.  

PubMed

The addition of Aspergillus oryzae fermentation extract (Amaferm) increased milk flow and mean 3.5% FCM production during the latter stages of the full lactation trial compared with the control group and the Aspergillus oryzae fermentation extract plus yeast culture plus mineral-vitamin supplement (VitaFerm) group. Based on the differences observed when FCM production was determined for the cows at various stages of lactation, Amaferm apparently had its greatest effect during the early stages of the lactation cycle and subsequent milk production was likely a result of higher initial production. The response difference observed between the Amaferm and VitaFerm treatments could have resulted from the additional minerals provided by the VitaFerm compared with the Amaferm and control groups. PMID:2283420

Kellems, R O; Lagerstedt, A; Wallentine, M V

1990-10-01

425

Polymer pendant ligand chemistry. 3. A biomimetic approach to selective metal ion removal and recovery from aqueous solution with polymer-supported sulfonated catechol and linear catechol amide ligands  

SciTech Connect

The design of organic ligands to selectively remove and recover metal ions from aqueous solution is a new and important area of environmental inorganic chemistry. One approach to designing organic ligands for these purposes is to use biological systems as examples for selective metal ion complexation. Thus, the authors report results on the synthesis of several biomimetically important polymer-supported, sulfonated catechol (PS-CATS), sulfonated bis(catechol) linear amide (PS-2-6-LICAMS), and sulfonated 3.3-linear tris(catechol) amide (PS-3,3-LICAMS) ligands that are chemically bonded to modified 6% cross-linked macroporous polystyrene-divinylbenzene beads (PS-DVB) for selective removal and recovery of environmentally and economically important metal ions from aqueous solution, as a function of pH. The Fe{sup 3+} ion selectivity was dramatically shown for PS-CATS, PS-2-6-LICAMS and PS-3,3-LICAMS polymer beads in competition with a similar concentration of Cu{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, Ni{sup 2+}, Mg{sup 2+}, Al{sup 3+}, and Cr{sup 3+} ions at pH 1-3, while metal ion selectivity could be changed at higher pH values in the absence of Fe{sup 3+} (for example, Hg{sup 2+} at pH 3). Rates of removal and recovery of the Fe{sup 3+} ion with the PS-CATS, PS-2-6LICAMS and PS-3,3-LICAMS polymer beads were also studied as well as relative equilibrium selectivity coefficient (K{sub m}) values for all metal competition studies.

Huang, Song-Ping; Li, Wei; Franz, K.J.; Albright, R.L.; Fish, R.H. [Univ. of California, Berkeley, CA (United States)

1995-05-24

426

Properties of ubiquinol oxidase reconstituted from ubiquinol-cytochrome c reductase, cytochrome c and cytochrome c oxidase.  

PubMed Central

Ubiquinol-cytochrome c reductase (Complex III), cytochrome c and cytochrome c oxidase can be combined to reconstitute antimycin-sensitive ubiquinol oxidase activity. In 25 mM-acetate/Tris, pH 7.8, cytochrome c binds at high-affinity sites (KD = 0.1 microM) and low-affinity sites (KD approx. 10 microM). Quinol oxidase activity is 50% of maximal activity when cytochrome c is bound to only 25% of the high affinity sites. The other 50% of activity seems to be due to cytochrome c bound at low-affinity sites. Reconstitution in the presence of soya-bean phospholipids prevents aggregation of cytochrome c oxidase and gives rise to much higher rates of quinol oxidase. The cytochrome c dependence was unaltered. Antimycin curves have the same shape regardless of lipid/protein ratio, Complex III/cytochrome c oxidase ratio or cytochrome c concentration. Proposals on the nature of the interaction between Complex III, cytochrome c and cytochrome c oxidase are considered in the light of these results. PMID:6284131

Diggens, R J; Ragan, C I

1982-01-01

427

CotA, a Multicopper Oxidase from Bacillus pumilus WH4, Exhibits Manganese-Oxidase Activity  

PubMed Central

Multicopper oxidases (MCOs) are a family of enzymes that use copper ions as cofactors to oxidize various substrates. Previous research has demonstrated that several MCOs such as MnxG, MofA and MoxA can act as putative Mn(II) oxidases. Meanwhile, the endospore coat protein CotA from Bacillus species has been confirmed as a typical MCO. To study the relationship between CotA and the Mn(II) oxidation, the cotA gene from a highly active Mn(II)-oxidizing strain Bacillus pumilus WH4 was cloned and overexpressed in Escherichia coli strain M15. The purified CotA contained approximately four copper atoms per molecule and showed spectroscopic properties typical of blue copper oxidases. Importantly, apart from the laccase activities, the CotA also displayed substantial Mn(II)-oxidase activities both in liquid culture system and native polyacrylamide gel electrophoresis. The optimum Mn(II) oxidase activity was obtained at 53°C in HEPES buffer (pH 8.0) supplemented with 0.8 mM CuCl2. Besides, the addition of o-phenanthroline and EDTA both led to a complete suppression of Mn(II)-oxidizing activity. The specific activity of purified CotA towards Mn(II) was 0.27 U/mg. The Km, Vmax and kcat values towards Mn(II) were 14.85ą1.17 mM, 3.01×10?6ą0.21 Mˇmin?1 and 0.32ą0.02 s?1, respectively. Moreover, the Mn(II)-oxidizing activity of the recombinant E. coli strain M15-pQE-cotA was significantly increased when cultured both in Mn-containing K liquid medium and on agar plates. After 7-day liquid cultivation, M15-pQE-cotA resulted in 18.2% removal of Mn(II) from the medium. Furthermore, the biogenic Mn oxides were clearly observed on the cell surfaces of M15-pQE-cotA by scanning electron microscopy. To our knowledge, this is the first report that provides the direct observation of Mn(II) oxidation with the heterologously expressed protein CotA, Therefore, this novel finding not only establishes the foundation for in-depth study of Mn(II) oxidation mechanisms, but also offers a potential biocatalyst for Mn(II) removal. PMID:23577125

Su, Jianmei; Bao, Peng; Bai, Tenglong; Deng, Lin; Wu, Hui; Liu, Fan; He, Jin

2013-01-01

428

Rice bacterial blight pathogen Xanthomonas oryzae pv. oryzae produces multiple DSF-family signals in regulation of virulence factor production  

PubMed Central

Background Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of rice bacterial blight disease. Xoo produces a range of virulence factors, including EPS, extracellular enzyme, iron-chelating siderophores, and type III-secretion dependent effectors, which are collectively essential for virulence. Genetic and genomics evidence suggest that Xoo might use the diffusible signal factor (DSF) type quorum sensing (QS) system to regulate the virulence factor production. However, little is known about the chemical structure of the DSF-like signal(s) produced by Xoo and the factors influencing the signal production. Results Xoo genome harbours an rpf cluster comprising rpfB, rpfF, rpfC and rpfG. The proteins encoded by these genes are highly homologous to their counterparts in X. campestris pv. campestris (Xcc), suggesting that Xcc and Xoo might use similar mechanisms for DSF biosynthesis and autoregulation. Consistent with in silico analysis, the rpfF mutant was DSF-deficient and the rpfC mutant produced about 25 times higher DSF-like activity than the wild type Xoo strain KACC10331. From the supernatants of rpfC mutant, we purified three compounds showing strong DSF-like activity. Mass spectrometry and NMR analysis revealed that two of them were the previously characterized DSF and BDSF; the third one was a novel unsaturated fatty acid with 2 double bonds and was designated as CDSF in this study. Further analysis showed that all the three DSF-family signals were synthesized via the enzyme RpfF encoded by Xoo2868. DSF and BDSF at a final concentration of 3 ?M to the rpfF mutant could fully restore its extracellular xylanase activity and EPS production to the wild type level, but CDSF was less active than DSF and BDSF in induction of EPS and xylanase. DSF and CDSF shared a similar cell density-dependent production time course with the maximum production being detected at 42 h after inoculation, whereas the maximum production of BDSF was observed at 36 h after inoculation. When grown in a rich medium such as YEB, LB, PSA, and NYG, Xoo produced all the three signals with the majority being DSF. Whereas in nutritionally poor XOLN medium Xoo only produced BDSF and DSF but the majority was BDSF. Conclusions This study demonstrates that Xoo and Xcc share the conserved mechanisms for DSF biosynthesis and autoregulation. Xoo produces DSF, BDSF and CDSF signals in rich media and CDSF is a novel signal in DSF-family with two double bonds. All the three DSF-family signals promote EPS production and xylanase activity in Xoo, but CDSF is less active than its analogues DSF and BDSF. The composition and ratio of the three DSF-family signals produced by Xoo are influenced by the composition of culture media. PMID:20615263

2010-01-01

429

Synergetic effects in the flow injection analysis determination of catechol in the presence of excess ascorbic acid by series dual-band amperometric detection 1 Presented at: European Society for Electroanalytical Chemistry `98, Seventh European Conference on Electroanalysis, University of Coimbra, Coimbra, Portugal, 24–28 May 1998. 1  

Microsoft Academic Search

The deviations at high concentrations (>10?5M) in the calibration curves for the determination of catechol in catechol\\/ascorbic acid mixtures by flow injection analysis using series dual-band poly(3-methylthiophene)-coated electrodes has been re-examined. The cyclic voltammetry (at pH?7.4) of catechol\\/ascorbate and catechol\\/urate mixtures and NMR measurements show these deviations are the result of the simultaneous homogeneous catalytic reaction of dehydrocatechol with ascorbate.

Hong Zhang; Suzanne K. Lunsford; Ozcan Ceylan; Anthony I Khaskelis; Nada Atta; Ahmed Galal; Sven Hausner; Judith F Rubinson; George C Russell; Hans Zimmer; George P Kreishman

1999-01-01

430

The broad bacterial blight resistance of rice line CBB23 is triggered by a novel transcription activator-like (TAL) effector of Xanthomonas oryzae pv. oryzae.  

PubMed

Bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), is not only a disease devastating rice production worldwide, but also an ideal model system for the study of the interaction between plants and their bacterial pathogens. The rice near-isogenic line (NIL) CBB23, derived from a cross between a wild rice Oryza rufipogon accession (RBB16) and a susceptible indica rice variety (Jingang 30), is highly resistant to all field Xoo strains tested so far. Although the BB resistance of CBB23 has been widely used in rice breeding programmes, the mechanism of its extremely broad-spectrum resistance remains unknown. Here, we report the molecular cloning of an avirulence gene, designated as avrXa23, from Xoo strain PXO99(A) . We validate that AvrXa23, a novel transcription activator-like effector, specifically triggers the broad-spectrum BB resistance in CBB23. The prevalence of avrXa23 in all 38 Xoo strains surveyed may explain the broad-spectrum feature of BB resistance in CBB23. The results will significantly facilitate the molecular cloning of the corresponding resistance (R) gene in the host, and provide new insights into our understanding of the molecular mechanism for broad-spectrum disease resistance in plants. PMID:24286630

Wang, Chun-Lian; Qin, Teng-Fei; Yu, Hong-Man; Zhang, Xiao-Ping; Che, Jin-Ying; Gao, Ying; Zheng, Chong-Ke; Yang, Bing; Zhao, Kai-Jun

2014-05-01

431

Catechol-O-methyltransferase (COMT) influences the connectivity of the prefrontal cortex at rest  

PubMed Central

Catechol-O-methyltransferase (COMT) modulates dopamine in the prefrontal cortex (PFC) and influences PFC dopamine-dependent cognitive task performance. A human COMT polymorphism (Val158Met) alters enzyme activity and is associated with both the activation and functional connectivity of the PFC during task performance, particularly working memory. Here, we used functional magnetic resonance imaging and a data-driven, independent components analysis (ICA) approach to compare resting state functional connectivity within the executive control network (ECN) between young, male COMT Val158 (n = 27) and Met158 (n = 28) homozygotes. COMT genotype effects on grey matter were assessed using voxel-based morphometry. COMT genotype significantly modulated functional connectivity within the ECN, which included the head of the caudate, and anterior cingulate and frontal cortical regions. Val158 homozygotes showed greater functional connectivity between a cluster within the left ventrolateral PFC and the rest of the ECN (using a threshold of Z > 2.3 and a family-wise error cluster significance level of p < 0.05). This difference occurred in the absence of any alterations in grey matter. Our data show that COMT Val158Met affects the functional connectivity of the PFC at rest, complementing its prominent role in the activation and functional connectivity of this region during cognitive task performance. The results suggest that genotype-related differences in prefrontal dopaminergic tone result in neuroadaptive changes in basal functional connectivity, potentially including subtle COMT genotype-dependent differences in the relative coupling of task-positive and task-negative regions, which could in turn contribute to its effects on brain activation, connectivity, and behaviour. PMID:23228511

Tunbridge, Elizabeth M.; Farrell, Sarah M.; Harrison, Paul J.; Mackay, Clare E.

2013-01-01

432

Open study of the catechol-O-methyltransferase inhibitor tolcapone in major depressive disorder.  

PubMed

Tolcapone is a catechol-O-methyltransferase (COMT) inhibitor that has shown efficacy in the treatment of Parkinson's disease. The authors undertook the first study on the efficacy of this COMT inhibitor in the treatment of major depressive disorder (MDD). The authors also wanted to assess the effects of tolcapone on the choline and myoinositol resonances in the left caudate and dorsolateral frontal lobe through proton magnetic resonance spectroscopy and on whole blood levels of S-adenosyl-L-methionine (SAMe). The study enrolled 21 adults (10 men and 11 women; mean age, 42.6 +/- 9.6 years) with MDD, which was diagnosed using the Structured Clinical Interview for DSM-IV, and an initial score of > or = 16 on the 17-item Hamilton Rating Scale for Depression (HAM-D-17). Patients were then treated openly for 8 weeks with tolcapone 400 mg twice daily. Treatment efficacy was assessed with the HAM-D-17, the Clinical Global Impressions Severity (CGI-S) scale, and the Beck Depression Inventory (BDI). Among all subjects (N = 21), there were significant (p < .0001) decreases at endpoint in HAM-D-17 scores (from 19.4 +/- 2.9 to 10.7 +/- 5.5), CGI-S scores (from 3.9 +/- 0.6 to 2.4 +/- 1.1), and BDI scores (from 21.6 +/- 8.1 to 12.3 +/- 8.6). Eight patients (38%) dropped out before completing the 8-week open study because of diarrhea, elevated liver function tests, increased anxiety, and noncompliance. No significant effects were noted on choline and myoinositol resonance or on SAMe levels in whole blood before and after 2 weeks of tolcapone treatment. The preliminary results suggest that tolcapone may be a promising agent in the treatment of MDD. Furthermore, double-blind, placebo-controlled studies are necessary to confirm this impression. PMID:10440460

Fava, M; Rosenbaum, J F; Kolsky, A R; Alpert, J E; Nierenberg, A A; Spillmann, M; Moore, C; Renshaw, P; Bottiglieri, T; Moroz, G; Magni, G

1999-08-01

433

How metal substitution affects the enzymatic activity of catechol-o-methyltransferase.  

PubMed

Catechol-O-methyltransferase (COMT) degrades catecholamines, such as dopamine and epinephrine, by methylating them in the presence of a divalent metal cation (usually Mg(II)), and S-adenosyl-L-methionine. The enzymatic activity of COMT is known to be vitally dependent on the nature of the bound metal: replacement of Mg(II) with Ca(II) leads to a complete deactivation of COMT; Fe(II) is slightly less than potent Mg(II), and Fe(III) is again an inhibitor. Considering the fairly modest role that the metal plays in the catalyzed reaction, this dependence is puzzling, and to date remains an enigma. Using a quantum mechanical / molecular mechanical dynamics method for extensive sampling of protein structure, and first principle quantum mechanical calculations for the subsequent mechanistic study, we explicate the effect of metal substitution on the rate determining step in the catalytic cycle of COMT, the methyl transfer. In full accord with experimental data, Mg(II) bound to COMT is the most potent of the studied cations and it is closely followed by Fe(II), whereas Fe(III) is unable to promote catalysis. In the case of Ca(II), a repacking of the protein binding site is observed, leading to a significant increase in the activation barrier and higher energy of reaction. Importantly, the origin of the effect of metal substitution is different for different metals: for Fe(III) it is the electronic effect, whereas in the case of Ca(II) it is instead the effect of suboptimal protein structure. PMID:23056605

Sparta, Manuel; Alexandrova, Anastassia N

2012-01-01

434

Genetic Polymorphisms of Catechol-O-Methyltransferase Modify the Neurobehavioral Effects of Mercury in Children  

PubMed Central

Mercury (Hg) is neurotoxic and children may be particularly susceptible to this effect. A current major challenge is identification of children who may be uniquely susceptible to Hg toxicity because of genetic disposition. This study examined the hypothesis that genetic variants of catechol-O-methyltransferase (COMT) that are reported to alter neurobehavioral functions that are also affected by Hg in adults might modify the adverse neurobehavioral effects of Hg exposure in children. Five hundred and seven children, 8–12 yr of age at baseline, participated in a clinical trial to evaluate the neurobehavioral effects of Hg from dental amalgam tooth fillings. Subjects were evaluated at baseline and at seven subsequent annual intervals for neurobehavioral performance and urinary Hg levels. Following the clinical trial, genotyping assays were performed for single-nucleotide polymorphisms (SNPs) of COMT rs4680, rs4633, rs4818, and rs6269 on biological samples provided by 330 of the trial participants. Regression-modeling strategies were employed to evaluate associations between allelic status, Hg exposure, and neurobehavioral test outcomes. Similar analysis was performed using haplotypes of COMT SNPs. Among girls, few interactions for Hg exposure and COMT variants were found. In contrast, among boys, numerous gene–Hg interactions were observed between individual COMT SNPs, as well as with a common COMT haplotype affecting multiple domains of neurobehavioral function. These findings suggest increased susceptibility to the adverse neurobehavioral effects of Hg among children with common genetic variants of COMT, and may have important implications for strategies aimed at protecting children from the potential health risks associated with Hg exposure. PMID:24593143

Woods, James S.; Heyer, Nicholas J.; Russo, Joan E.; Martin, Michael D.; Pillai, Pradeep B.; Bammler, Theodor K.; Farin, Federico M.

2014-01-01

435

A Novel Catechol-O-Methyltransferase Variant Associated with Human Disc Degeneration  

PubMed Central

Background: Disc degeneration and its associated low back pain are a major health care concern causing disability with a prominent role in this country's medical, social and economic structure. Low back pain is devastating and influences the quality of life for millions. Low back pain lifetime prevalence approximates 80% with an estimated direct cost burden of $86 billion per year. Back pain patients incur higher costs, greater health care utilization, and greater work loss than patients without back pain. Methods: Research was performed following approval of our Institutional Review Board. DNA was isolated, processed and amplified using routine techniques. Amplified DNA was hybridized to Affymetrix Genome-Wide Human SNP Arrays. Quality control and genotyping analysis were performed using Affymetrix Genotyping Console. The Birdseed v2 algorithm was used for genotyping analysis. 2589 SNPs were selected a priori to enter statistical analysis using lotistic regression in SAS. Results: Our objective was to search for novel single nucleotide polymorphisms (SNPs) associated with disc degeneration. Four SNPs were found to have a significant relationship to disc degeneration; three are novel. Rs165656, a new SNP found to be associated with disc degeneration, was in catechol-O-methyltransferase (COMT), a gene with well-recognized pain involvement, especially in female subjects (p=0.01). Analysis confirmed the previously association between COMT SNP rs4633 and disc degeneration. We also report two novel disc degeneration-related SNPs (rs2095019 and rs470859) located in intergenic regions upstream to thrombospondin 2. Conclusions: Findings contribute to the challenging field of disc degeneration and pain, and are important in light of the high clinical relevance of low back pain and the need for improved understanding of its fundamental basis. PMID:24904231

Gruber, Helen E.; Sha, Wei; Brouwer, Cory R.; Steuerwald, Nury; Hoelscher, Gretchen L.; Hanley, Edward N. Jr.

2014-01-01

436

Genetic association of catechol-O-methyltransferase val(158)met polymorphism in Saudi schizophrenia patients.  

PubMed

Schizophrenia is a complex neuropsychiatric disorder strongly associated with dopamine dysregulation. Catechol-O-methyl-transferase (COMT) is a candidate gene for schizophrenia that encodes an enzyme involved in the metabolic inactivation of dopamine. The COMT Val(158)Met polymorphism has been associated with schizophrenia and has significant inter- and intra-ethnic variations. We examined a possible association between the COMT Val(158)Met polymorphism and schizophrenia in Saudis, taking into account gender and functional symptoms. Saudi subjects including 172 unrelated schizophrenia patients and 177 matched controls were analyzed for allele and genotype distribution of the COMT Val(158)Met polymorphism. We found significant differences in allele and genotype frequencies between patients and controls. The frequencies of Met(158) allele (A) and genotype Val(158)Met (GA) were significantly higher in patients compared to those in controls. On the other hand, the frequencies of Val(158) allele (G) and genotype Val(158)Val (GG) were significantly higher in controls than those in patients. We found a significant association of the COMT Val(158)Met polymorphism with schizophrenia. Moreover, male patients with the COMT Val(158)Met polymorphism had increased risk for schizophrenia compared to female subjects. However, no association was noticed with the COMT Val(158)Met polymorphism and negative or positive symptoms of schizophrenia. These results provide evidence for a role of the COMT Val(158)Met polymorphism in the etiopathophysiology of schizophrenia in Saudi population. It appears that the association of the COMT Val(158)Met polymorphism with schizophrenia is mediated by gender. PMID:24782165

Al-Asmary, S; Kadasah, S; Arfin, M; Tariq, M; Al-Asmari, A

2014-01-01

437

How Metal Substitution Affects the Enzymatic Activity of Catechol-O-Methyltransferase  

PubMed Central

Catechol-O-methyltransferase (COMT) degrades catecholamines, such as dopamine and epinephrine, by methylating them in the presence of a divalent metal cation (usually Mg(II)), and S-adenosyl-L-methionine. The enzymatic activity of COMT is known to be vitally dependent on the nature of the bound metal: replacement of Mg(II) with Ca(II) leads to a complete deactivation of COMT; Fe(II) is slightly less than potent Mg(II), and Fe(III) is again an inhibitor. Considering the fairly modest role that the metal plays in the catalyzed reaction, this dependence is puzzling, and to date remains an enigma. Using a quantum mechanical / molecular mechanical dynamics method for extensive sampling of protein structure, and first principle quantum mechanical calculations for the subsequent mechanistic study, we explicate the effect of metal substitution on the rate determining step in the catalytic cycle of COMT, the methyl transfer. In full accord with experimental data, Mg(II) bound to COMT is the most potent of the studied cations and it is closely followed by Fe(II), whereas Fe(III) is unable to promote catalysis. In the case of Ca(II), a repacking of the protein binding site is observed, leading to a significant increase in the activation barrier and higher energy of reaction. Importantly, the origin of the effect of metal substitution is different for different metals: for Fe(III) it is the electronic effect, whereas in the case of Ca(II) it is instead the effect of suboptimal protein structure. PMID:23056605

Sparta, Manuel; Alexandrova, Anastassia N.

2012-01-01

438

Catechol-O-methyltransferase gene haplotypes in Mexican and Spanish patients with fibromyalgia  

PubMed Central

Autonomic dysfunction is frequent in patients with fibromyalgia (FM). Heart rate variability analyses have demonstrated signs of ongoing sympathetic hyperactivity. Catecholamines are sympathetic neurotransmitters. Catechol-O-methyltransferase (COMT), an enzyme, is the major catecholamine-clearing pathway. There are several single-nucleotide polymorphisms (SNPs) in the COMT gene associated with the different catecholamine-clearing abilities of the COMT enzyme. These SNPs are in linkage disequilibrium and segregate as 'haplotypes'. Healthy females with a particular COMT gene haplotype (ACCG) producing a defective enzyme are more sensitive to painful stimuli. The objective of our study was to define whether women with FM, from two different countries (Mexico and Spain), have the COMT gene haplotypes that have been previously associated with greater sensitivity to pain. All the individuals in the study were female. Fifty-seven Mexican patients and 78 Spanish patients were compared with their respective healthy control groups. All participants filled out the Fibromyalgia Impact Questionnaire (FIQ). Six COMT SNPs (rs2097903, rs6269, rs4633, rs4818, rs4680, and rs165599) were genotyped from peripheral blood DNA. In Spanish patients, there was a significant association between three SNPs (rs6269, rs4818, and rs4680) and the presence of FM when compared with healthy controls. Moreover, in Spanish patients with the 'high pain sensitivity' haplotype (ACCG), the disease, as assessed by the FIQ, was more severe. By contrast, Mexican patients displayed only a weak association between rs6269 and rs165599, and some FIQ subscales. In our group of Spanish patients, there was an association between FM and the COMT haplotype previously associated with high pain sensitivity. This association was not observed in Mexican patients. Studies with a larger sample size are needed in order to verify or amend these preliminary results. PMID:17961261

Vargas-Alarcón, Gilberto; Fragoso, José-Manuel; Cruz-Robles, David; Vargas, Angélica; Vargas, Alfonso; Lao-Villadóniga, José-Ignacio; García-Fructuoso, Ferrán; Ramos-Kuri, Manuel; Hernández, Fernando; Springall, Rashidi; Bojalil, Rafael; Vallejo, Maite; Martínez-Lavín, Manuel

2007-01-01

439

Genetic polymorphisms of catechol-O-methyltransferase modify the neurobehavioral effects of mercury in children.  

PubMed

Mercury (Hg) is neurotoxic and children may be particularly susceptible to this effect. A current major challenge is identification of children who may be uniquely susceptible to Hg toxicity because of genetic disposition. This study examined the hypothesis that genetic variants of catechol-O-methyltransferase (COMT) that are reported to alter neurobehavioral functions that are also affected by Hg in adults might modify the adverse neurobehavioral effects of Hg exposure in children. Five hundred and seven children, 8-12 yr of age at baseline, participated in a clinical trial to evaluate the neurobehavioral effects of Hg from dental amalgam tooth fillings. Subjects were evaluated at baseline and at seven subsequent annual intervals for neurobehavioral performance and urinary Hg levels. Following the clinical trial, genotyping assays were performed for single-nucleotide polymorphisms (SNPs) of COMT rs4680, rs4633, rs4818, and rs6269 on biological samples provided by 330 of the trial participants. Regression-modeling strategies were employed to evaluate associations between allelic status, Hg exposure, and neurobehavioral test outcomes. Similar analysis was performed using haplotypes of COMT SNPs. Among girls, few interactions for Hg exposure and COMT variants were found. In contrast, among boys, numerous gene-Hg interactions were observed between individual COMT SNPs, as well as with a common COMT haplotype affecting multiple domains of neurobehavioral function. These findings suggest increased susceptibility to the adverse neurobehavioral effects of Hg among children with common genetic variants of COMT, and may have important implications for strategies aimed at protecting children from the potential health risks associated with Hg exposure. PMID:24593143

Woods, James S; Heyer, Nicholas J; Russo, Joan E; Martin, Michael D; Pillai, Pradeep B; Bammler, Theodor K; Farin, Federico M

2014-01-01

440

Effect of a natural mineral-rich water on catechol-O-methyltransferase function.  

PubMed

Catechol-O-methyltransferase (COMT) is a magnesium-dependent, catecholamine-metabolizing enzyme, whose impaired activity has been positively associated with cardiovascular diseases, particularly hypertension. Consumption of some natural mineral-rich waters has been shown to exert protective effects on cardiovascular risk factors, eg. by decreasing arterial blood pressure and blood lipids. However, the molecular mechanisms underlying these effects are still poorly understood. So, the aim of this work was to investigate the effect of natural mineral-rich water ingestion upon liver and adrenal glands COMT expression and activity in Wistar Han rats. Over a seven-week period, animals had access to one of the following three drinking solutions: 1) tap water (control group; TW), 2) tap water with added Na(+) (to make the same concentration as in the MW group (TWNaCl group), or 3) natural mineral-rich water [Pedras Salgadas(Ž), which is very rich in bicarbonate, and with higher sodium, calcium and magnesium content than control tap water (MW group)]. COMT expression and activity were determined by RT-PCR and HPLC-ED, respectively. A higher hepatic COMT activity was found in the MW group compared with the TW and TWNaCl groups. On the other hand, adrenal gland COMT mRNA expression decreased in the MW group compared to TW group. In conclusion, the ability of natural mineral-rich waters to increase hepatic COMT activity may eventually explain the positive cardiovascular effects associated with the consumption of some natural mineral-rich waters. PMID:25560240

Bastos, Pedro; Araújo, Joăo Ricardo; Azevedo, Isabel; Martins, Maria Joăo; Ribeiro, Laura

2014-01-01