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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

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

PubMed

A homology search against public fungal genome sequences was performed to discover novel secreted tyrosinases. The analyzed proteins could be divided in two groups with different lengths (350-400 and 400-600 residues), suggesting the presence of 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 characterization. AoCO4 was expressed in Trichoderma reesei under the strong cbh1 promoter. Expression of AoCO4 in T. reesei resulted in high yields of extracellular enzyme, corresponding to 1.5 g L(-1) production of the enzyme. AoCO4 was purified with a two-step purification procedure, consisting of cation and anion exchange chromatography. The N-terminal analysis of the protein revealed N-terminal processing taking place in the Kex2/furin-type protease cleavage site and removing the first 51 amino acids from the putative N-terminus. AoCO4 activity was tested on various substrates, and the highest activity was found on 4-tert-butylcatechol. Because no activity was detected on L-tyrosine and on L-dopa, AoCO4 was classified as a catechol oxidase. AoCO4 showed the highest activity within an acidic and neutral pH range, having an optimum at pH 5.6. AoCO4 showed good pH stability within a neutral and alkaline pH range and good thermostability up to 60 degrees C. The UV-visible and circular dichroism spectroscopic analysis suggested that the folding of the protein was correct. PMID:19798497

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

2009-10-02

4

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

5

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

6

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

7

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

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

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

10

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

11

Structural and spectroscopic studies of a model for catechol oxidase.  

PubMed

A binuclear copper complex, [Cu2(BPMP) (OAc)2][ClO4] x H2O, has been prepared using the binucleating ligand 2,6-bis[bis(pyridin-2-ylmethylamino)methyl]-4-methylphenol (H-BPMP). The X-ray crystal structure reveals the copper centers to have a five-coordinate square pyramidal geometry, with the acetate ligands bound terminally. The bridging phenolate occupies the apical position of the square-based pyramids and magnetic susceptibility, electron paramagnetic resonance (EPR) and variable-temperature variable-field magnetic circular dichroism (MCD) measurements indicate that the two centers are very weakly antiferromagnetically coupled (J = -0.6 cm(-1)). Simulation of the dipole-dipole-coupled EPR spectrum showed that in solution the Cu-O-Cu angle was increased from 126 degrees to 160 degrees and that the internuclear distance was larger than that observed crystallographically. The high-resolution spectroscopic information obtained has been correlated with a detailed ligand-field analysis to gain insight into the electronic structure of the complex. Symmetry arguments have been used to demonstrate that the sign of the MCD is characteristic of the tetragonally elongated environment. The complex also displays catecholase activity (k(cat) = 15 +/- 1.5 min(-1), K(M) = 6.4 +/- 1.8 mM), which is compared with other dicopper catechol oxidase models. PMID:18188615

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

2008-05-01

12

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

PubMed

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 not in the purified, mature form of catechol oxidase. Superimposition of the 3D structures of the native hemocyanin and catechol oxidase reveals a close relationship except for an additional C-terminal domain only found in the hemocyanin structure. As sequence alignment shows good homology this domain of the hemocyanin structure was used as a template to model the 3D structure of the C-terminal extension peptide of catechol oxidase. As hemocyanins show no or only weak catecholase activity due to this domain this indicates an inhibitory function of this extension peptide. Beside this possible shielding function for the precursor form, evidence for a function in copper-uptake also increases due to the location of three histidine residues in the model. PMID:11931976

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

2002-04-10

13

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

14

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

15

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

16

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

17

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

18

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

19

An association study of catechol- O-methyltransferase and monoamine oxidase A polymorphisms and personality traits in Koreans  

Microsoft Academic Search

Catechol-O-methyltransferase (COMT) and monoamine oxidase A (MAOA) are both involved in the degradation of various biogenic amines which have been hypothesized to have a relationship with personality traits. The present study investigated the possible relationships between the genotypes of COMT Val158Met and MAOA-uVNTR polymorphisms and personality traits measured by the Temperament and Character Inventory (TCI). We recruited 286 normal, unrelated

Se Joo Kim; Young Shin Kim; Shin Young Kim; Hong Shick Lee; Chan-Hyung Kim

2006-01-01

20

The Genetic Control and Biochemical Modification of Catechol Oxidase in Maize  

PubMed Central

Three isozyme variants of catechol oxidase have been shown to be determined by alleles of a gene, Cx, which has been located on chromosome 10 less than 0.1 recombination units from the endosperm marker du1.—The extractable form of the enzyme is modified by an endogeneous "modifier" which appears to function as an enzyme substrate. Enzyme and modifier are functionally isolated in intact cells. Modified enzyme has altered kinetics, does not migrate in electrophoresis and most probably results from a "tanning" of the enzyme by reaction products. The content of modifier varies in different lines and is genetically determined by gene(s) independent of Cx. Treatment with maleic hydrazide causes a ten-fold reduction in the modifier content of seedlings, allowing the enzyme to be extracted in an unmodified form which will migrate in electrophoresis.—This system of enzyme and modifier fits the requirements of hypersensitive disease resistance in plants and may provide a test system to investigate the biochemical basis of disease resistance.

Pryor, Tony; Schwartz, Drew

1973-01-01

21

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

22

Effect of amphetamine on brain catecholamines, brain beta-endorphin, serum prolactin, catechol-O-methyltransferase and monoamine oxidase of various organs in the rat.  

PubMed

Rats were treated with amphetamine to induce an amphetamine psychosis which resembles paranoid schizophrenia. Brain catecholamines, brain beta-endorphin, serum prolactin as well as catechol-O-methyltransferase and monoamine oxidase were subsequently measured. The norepinephrine levels were significantly lower in brain regions of rats treated with amphetamine whereas levels of dopamine and beta-endorphin remained the same. No significant changes were found in the levels of catechol-O-methyltransferase, monoamine oxidase and serum prolactin. In view of recent findings by other investigators in this field, our results suggest an important role of the adrenergic system in the pathogenesis of amphetamine psychosis. PMID:2936351

Agarwal, D P; Hoo, J J; Tjaden, A; Nishigaki, I; Beckermann, W J; Pahnke, V; Goedde, H W

1985-01-01

23

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

24

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

25

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

2004-09-22

26

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

27

Oryza  

Microsoft Academic Search

\\u000a Rice (Oryza sativa L) is an important cereal for one-third of the world’s population. Its productivity is continually threatened by a series\\u000a of biotic and abiotic stresses. There is thus an urgent need to broaden the gene pool of rice for developing varieties with\\u000a high yield and resistance to several stresses. Wild species of Oryza are a reservoir of genes

Darshan S. Brar; Kuldeep Singh

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

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

31

Heterologous expression and biochemical characterization of novel pyranose 2-oxidases from the ascomycetes Aspergillus nidulans and Aspergillus oryzae.  

PubMed

A gene encoding a pyranose 2-oxidase (POx; pyranose/oxygen 2-oxidoreductase; glucose 2-oxidase; EC 1.1.3.10) was identified in the genome of the ascomycete Aspergillus nidulans. Attempts to isolate POx directly from A. nidulans cultures or to homologously overexpress the native POx (under control of the constitutive gpdA promoter) in A. nidulans were unsuccessful. cDNA encoding POx was synthesized from mRNA and expressed in Escherichia coli, and the enzyme was subsequently purified and characterized. A putative pyranose 2-oxidase-encoding gene was also identified in the genome of Aspergillus oryzae. The coding sequence was synthetically produced and was also expressed in E. coli. Both purified enzymes were shown to be flavoproteins consisting of subunits of 65 kDa. The A. nidulans enzyme was biochemically similar to POx reported in literature. From all substrates, the highest catalytic efficiency was found with D-glucose. In addition, the enzyme catalyzes the two-electron reduction of 1,4-benzoquinone, several substituted benzoquinones and 2,6-dichloroindophenol. As judged by the catalytic efficiencies (k (cat)/k(m)), some of these quinone electron acceptors are better substrates for pyranose oxidase than oxygen. The enzyme from A. oryzae was physically similar but showed lower kinetic constants compared to the enzyme from A. nidulans. Distinct differences in the stability of the two enzymes may be attributed to a deletion and an insertion in the sequence, respectively. PMID:21968652

Pisanelli, Ines; Wührer, Petra; Reyes-Dominguez, Yazmid; Spadiut, Oliver; Haltrich, Dietmar; Peterbauer, Clemens

2011-10-04

32

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)(µ-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

33

The activity of catechol-O-methyltransferase and monoamine oxidase in the uterine artery of pigs during the oestrous cycle.  

PubMed

Activities of catechol-O-methyltransferase (COMT), total monoamine oxidase (MAO) and both types of MAO-A and MAO-B activities were examined in uterine artery on the 0-2nd, 13-14th and 16-18th days of the oestrous cycle in pigs. It was shown that activity of COMT was the lowest on the 0-2nd day, while on the 16-18th day of the oestrous cycle it increased by 52.4% (p < 0.05). Total activity of MAO was the highest at periovulatory phase, whereas on days 13-14 and 16-18 of oestrous cycle is was lower by 83.5% (p < 0.01) and 58.1% (p < 0.01) compared with its activity at periovulatory phase, and was higher on day 16-18 by 153.3% (p < 0.01) in relation to the luteal phase (13-14th day). MAO-A activity was 31.3% (p < 0.01) and MAO-B 62.5% (p < 0.05) of the total activity of MAO. Their activities were also highest at periovulatory phase, then decreased by 86.8-87.4% (p < 0.01) on 13-14th day and by 54.8-57.5% (p < 0.01) or 16-18th day of oestrous cycle. Activities of MAO-A and MAO-B were higher by 223.0-258.2% (p < 0.01) on 16-18th day in relation to the luteal phase (13-14th day). On that base we suppose that variations of COMT and MAO activities can significantly change the catecholamines content in the blood vessels of reproductive organs of pigs. PMID:8055053

Dynarowicz, I; Paprocki, M

1993-01-01

34

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

35

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.

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

2010-01-01

36

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

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 regulation/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

2009-11-10

37

Secreted fungal sulfhydryl oxidases: sequence analysis and characterisation of a representative flavin-dependent enzyme from Aspergillus oryzae  

Microsoft Academic Search

BACKGROUND: Sulfhydryl oxidases are flavin-dependent enzymes that catalyse the formation of de novo disulfide bonds from free thiol groups, with the reduction of molecular oxygen to hydrogen peroxide. Sulfhydryl oxidases have been investigated in the food industry to remove the burnt flavour of ultraheat-treated milk and are currently studied as potential crosslinking enzymes, aiming at strengthening wheat dough and improving

Greta Faccio; Kristiina Kruus; Johanna Buchert; Markku Saloheimo

2010-01-01

38

A Community-Based Study of Cigarette Smoking Behavior in Relation to Variation in Three Genes Involved in Dopamine Metabolism: Catechol-O-methyltransferase (COMT), Dopamine Beta-Hydroxylase (DBH) and Monoamine Oxidase-A (MAO-A)  

PubMed Central

Objective Cigarette smoking behavior may be influenced by catechol-O-methlyltransferase (COMT), dopamine beta-hydroxylase (DBH), and monamine oxidase-A (MAO-A), genes that play roles in dopamine metabolism. The association between common polymorphisms of these genes and smoking behavior was assessed among 10,059 Caucasian volunteers in Washington County, MD in 1989. Methods Age-adjusted logistic regression was used to measure the association between variants of these single nucleotide polymorphisms and smoking initiation and persistent smoking. Results Overall, no association was seen between each genotype and smoking behavior. However, among younger (<54 years) women, the COMT GG genotype was positively associated with smoking initiation (OR=1.3; 95% CI: 1.1, 1.5), and the MAO-A TT genotype was inversely associated with persistent smoking (OR=0.5; 95% CI: 0.3, 0.9). Men who smoked fewer than 10 cigarettes per day were more likely to be persistent smokers if they had the COMT GG (OR=1.7; 95% CI: 1.0, 2.9) or the DBH GG (OR=1.6; 95% CI: 1.0, 2.6) genotypes. Conclusion Overall the results of this large community-based study do not provide evidence to support the presence of important associations between variants of COMT, DBH, or MAO-A and smoking initiation or persistent smoking.

Shiels, Meredith S.; Huang, Han Yao; Hoffman, Sandra C.; Shugart, Yin Yao; Bolton, Judy Hoffman; Platz, Elizabeth A.; Helzlsouer, Kathy J.; Alberg, Anthony J.

2008-01-01

39

Structural and Functional Models for the Dinuclear Copper Active Site in Catechol Oxidases: Syntheses, X-ray Crystal Structures, Magnetic and Spectral Properties, and X-ray Absorption Spectroscopic Studies in Solid State and in Solution.  

PubMed

Two novel tridentate dinucleating ligands containing benzimidazole were prepared, 1,3-bis(2-benzimidazolyl)-2-propanol (Hbbp, 1) and 1,5-bis(2-benzimidazolyl)-3-pentanol (Hbbpen, 2). Their complexing properties toward copper were studied in order to obtain structural and functional models for catechol oxidases. Syntheses and crystal structures of dinuclear Cu(II) complexes derived from these ligands are reported. [Cu(2)bbp(2)](ClO(4))(2).2MeOH, 3, crystallizes in the triclinic space group P&onemacr; with the following unit cell parameters: a = 7.702(3) Ĺ, b = 10.973(6) Ĺ, c = 12.396(6) Ĺ, alpha = 100.59(4) degrees, beta = 99.02(4) degrees, gamma = 98.90(4) degrees, V = 998.7(8) Ĺ(3), and Z = 1. [Cu(2)bbpen(2)](ClO(4))(2).3MeOH, 4, crystallizes in the orthorhombic space group Pccn, with the following unit cell parameters: a = 17.478(9) Ĺ, b = 18.795(8) Ĺ, c = 13.888(6) Ĺ, V = 4562.2(4) Ĺ(3), and Z = 4. Magnetic susceptibility measurements in the temperature ranges 4.6-459 K (3) and 4.6-425 K (4) indicate an antiferromagnetic coupling between the Cu(II) centers of both complexes. In order to determine the structures of the complexes in solution, XAS spectra (EXAFS and XANES) were recorded in the solid state and in solution. The interpretation of these data, including multiple scattering calculations, together with UV-vis titrations, shows that the complexes have the same structure in the crystalline state as well as in methanolic solution. Complex 4 is able to oxidize 3,5-di-tert-butylcatechol (3,5-DTBC) to the quinone (catecholase activity). This reaction was also studied by XAS and UV-vis spectroscopy. These measurements reveal the reduction of Cu(II) to Cu(I) accompanied by a decrease of the coordination number. PMID:11666546

Zippel, Frank; Ahlers, Friedhelm; Werner, Rüdiger; Haase, Wolfgang; Nolting, Hans-Friedrich; Krebs, Bernt

1996-05-22

40

New functional models for catechol oxidases  

Microsoft Academic Search

The new dinuclear copper(II) complexes [Cu2(L1)(?-OAc)](ClO4)2·CH3CN (1), [Cu2(L2)(CH3CN)2](ClO4)4·C2H5OH (2), [Cu2(L3)2(CH3CN)2](PF6)2 (3) and [Cu2(L4)2](PF6)2·2CH2Cl2 (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

41

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

42

Catechol oxidase activity of a series of new dinuclear copper(II) complexes with 3,5-DTBC and TCC as substrates: syntheses, X-ray crystal structures, spectroscopic characterization of the adducts and kinetic studies.  

PubMed

A series of dinuclear copper(II) complexes has been synthesized with the aim to investigate their applicability as potential structure and function models for the active site of catechol oxidase enzyme. They have been characterized by routine physicochemical techniques as well as by X-ray single-crystal structure analysis: [Cu 2(H 2L2 (2))(OH)(H 2O)(NO 3)](NO 3) 3.2H 2O ( 1), [Cu(HL1 (4))(H 2O)(NO 3)] 2(NO 3) 2.2H 2O ( 2), [Cu(L1 (1))(H 2O)(NO 3)] 2 ( 3), [Cu 2(L2 (3))(OH)(H 2O) 2](NO 3) 2, ( 4) and [Cu 2(L2 (1))(N 3) 3] ( 5) [L1 = 2-formyl-4-methyl-6R-iminomethyl-phenolato and L2 = 2,6-bis(R-iminomethyl)-4-methyl-phenolato; for L1 (1) and L2 (1), R = N-propylmorpholine; for L2 (2), R = N-ethylpiperazine; for L2 (3), R = N-ethylpyrrolidine, and for L1 (4), R = N-ethylmorpholine]. Dinuclear 1 and 4 possess two "end-off" compartmental ligands with exogenous mu-hydroxido and endogenous mu-phenoxido groups leading to intermetallic distances of 2.9794(15) and 2.9435(9) A, respectively; 2 and 3 are formed by two tridentate compartmental ligands where the copper centers are connected by endogenous phenoxido bridges with Cu-Cu separations of 3.0213(13) and 3.0152(15) A, respectively; 5 is built by an end-off compartmental ligand having exogenous mu-azido and endogenous mu-phenoxido groups with a Cu-Cu distance of 3.133(2) A (mean of two independent molecules). The catecholase activity of all of the complexes has been investigated in acetonitrile and methanol medium by UV-vis spectrophotometric study using 3,5-di- tert-butylcatechol (3,5-DTBC) and tetrachlorocatechol (TCC) as substrates. In acetonitrile medium, the conversion of 3,5-DTBC to 3,5-di- tert-butylbenzoquinone (3,5-DTBQ) catalyzed by 1- 5 is observed to proceed via the formation of two enzyme-substrate adducts, ES1 and ES2, detected spectroscopically for the first time. In methanol medium no such enzyme-substrate adduct has been detected, and the 3,5-DTBC to 3,5-DTBQ conversion is observed to be catalyzed by 1- 5 very efficiently. The substrate TCC forms an adduct with 2- 5 without performing further oxidation to TCQ due to the high reduction potential of TCC (in comparison with 3,5-DTBC). But most interestingly, 1 is observed to be effective even in TCC oxidation, a process never reported earlier. Kinetic experiments have been performed to determine initial rate of reactions (3,5-DTBC as substrate, in methanol medium) and the activity sequence is 1 > 5 > 2 = 4 > 3. A treatment on the basis of Michaelis-Menten model has been applied for kinetic study, suggesting that all five complexes exhibit very high turnover number, especially 1, which exhibits turnover number or K cat of 3.24 x 10 (4) (h (-1)), which is approximately 3.5 times higher than the most efficient catalyst reported to date for catecholase activity in methanol medium. PMID:18624404

Banu, Kazi Sabnam; Chattopadhyay, Tanmay; Banerjee, Arpita; Bhattacharya, Santanu; Suresh, Eringathodi; Nethaji, Munirathinam; Zangrando, Ennio; Das, Debasis

2008-07-15

43

The catalytic effect of tyrosinase upon oxidation of 2-hydroxyestradiol in presence of catechol.  

PubMed

The hydroxylating activity of mushroom tyrosinase has been utilized for over a decade in the preparation of 2-hydroxyestradiol from estradiol, yet this same enzyme is known to function as an oxidant of o-dihydric compounds to the corresponding o-quinones. It was questioned why catechol estrogens do not react further, particularly since the tyrosinase activity (hydroxylating) is exceeded many fold by the diphenol oxidase activity of the enzyme. This report describes that the catechol estrogen will react in presence of enzyme but only if catechol is also present. Diphenol oxidase activity was measured either by the polarographic oxygen-utilization technique or by changes in the absorption spectrum at 206 and 256 nm. The enzyme activity was standardized with catechol (Km = 5.2 X 10(-4) M). The steroid did not react with the enzyme if catechol was absent. With catechol, the steroid reacted rapidly and completely (Km = 4.2 X 10(-4) M). The consumption of oxygen with catechol and 2-hydroxyestradiol was additive and stoichiometric, 1 g-atom oxygen/mol of either substrate. Kinetic analysis shows that catechol functions as an activator of the tyrosinase. PMID:6430238

Jacobsohn, G M; Jacobsohn, M K

1984-07-01

44

Structures, magnetochemistry, spectroscopy, theoretical study, and catechol oxidase activity of dinuclear and dimer-of-dinuclear mixed-valence Mn(III)Mn(II) complexes derived from a macrocyclic ligand.  

PubMed

The work in this paper presents syntheses, characterization, magnetic properties (experimental and density functional theoretical), catecholase activity, and electrospray ionization mass spectroscopic (ESI-MS positive) studies of two mixed-valence dinuclear Mn(III)Mn(II) complexes, [Mn(III)Mn(II)L(?-O2CMe)(H2O)2](ClO4)2·H2O·MeCN (1) and [Mn(III)Mn(II)L(?-O2CPh)(MeOH)(ClO4)](ClO4) (2), and a Mn(III)Mn(II)Mn(II)Mn(III) complex, [{Mn(III)Mn(II)L(?-O2CEt)(EtOH)}2(?-O2CEt)](ClO4)3 (3), derived from the Robson-type macrocycle H2L, which is the [2 + 2] condensation product of 2,6-diformyl-4-methylphenol and 2,2-dimethyl-1,3-diaminopropane. In 1 and 2 and in two Mn(III)Mn(II) units in 3, the two metal centers are bridged by a bis(?-phenoxo)-?-carboxylate moiety. The two Mn(II) centers of the two Mn(III)Mn(II) units in 3 are bridged by a propionate moiety, and therefore this compound is a dimer of two dinuclear units. The coordination geometry of the Mn(III) and Mn(II) centers are Jahn-Teller distorted octahedral and distorted trigonal prism, respectively. Magnetic studies reveal weak ferro- or antiferromagnetic interactions between the Mn(III) and Mn(II) centers in 1 (J = +0.08 cm(-1)), 2 (J = -0.095 cm(-1)), and 3 (J1 = +0.015 cm(-1)). A weak antiferromagnetic interaction (J2 = -0.20 cm(-1)) also exists between the Mn(II) centers in 3. DFT methods properly reproduce the nature of the exchange interactions present in such systems. A magneto-structural correlation based on Mn-O bridging distances has been proposed to explain the different sign of the exchange coupling constants. Utilizing 3,5-di-tert-butyl catechol (3,5-DTBCH2) as the substrate, catecholase activity of all the three complexes has been checked in MeCN and MeOH, revealing that all three are active catalysts with Kcat values lying in the range 7.5-64.7 h(-1). Electrospray ionization mass (ESI-MS positive) spectra of the complexes 1-3 have been recorded in MeCN solutions, and the positive ions have been well characterized. ESI-MS positive spectrum of complex 1 in presence of 3,5-DTBCH2 has also been recorded, and a positive ion, [Mn(III)Mn(II)L(?-3,5-DTBC(2-))](+), having most probably a bridging catecholate moiety has been identified. PMID:23750907

Jana, Arpita; Aliaga-Alcalde, Núria; Ruiz, Eliseo; Mohanta, Sasankasekhar

2013-06-10

45

Properties of Polyphenol Oxidase Extracted from Zhonghuashoutao Peach Flesh  

Microsoft Academic Search

Objective)Properties of polyphenol oxidase extracted and purified from Zhonghuashoutao peach (Prunus persica L. var. densa Makino cv. Zhonghuashoutao) flesh were studied to investigate the theory of browning. (Method)Polyphenol oxidase activities of peach flesh were spectrophotometrically determined at 420 nm with catechol as substrate at different pH, temperatures and substrate concentrations and so on. (Result) The enzyme showed a single protein

DUAN Yu-quan; DONG Wei; ZHANG Ming-jing; FENG Shuang-qing; ZHAO Yu-mei

46

Structural and spectroscopic studies of a model for catechol oxidase  

Microsoft Academic Search

A binuclear copper complex, [Cu2(BPMP)(OAc)2][ClO4]·H2O, 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

47

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

Golbeck, John H.; Cammarata, Kirk V.

1981-01-01

48

Purification, characterization, and identification of a novel bifunctional catalase-phenol oxidase from Scytalidium thermophilum.  

PubMed

A novel bifunctional catalase with an additional phenol oxidase activity was isolated from a thermophilic fungus, Scytalidium thermophilum. This extracellular enzyme was purified ca. 10-fold with 46% yield and was biochemically characterized. The enzyme contains heme and has a molecular weight of 320 kDa with four 80 kDa subunits and an isoelectric point of 5.0. Catalase and phenol oxidase activities were most stable at pH 7.0. The activation energies of catalase and phenol oxidase activities of the enzyme were found to be 2.7 +/- 0.2 and 10.1 +/- 0.4 kcal/mol, respectively. The pure enzyme can oxidize o-diphenols such as catechol, caffeic acid, and L-DOPA in the absence of hydrogen peroxide and the highest oxidase activity is observed against catechol. No activity is detected against tyrosine and common laccase substrates such as ABTS and syringaldazine with the exception of weak activity with p-hydroquinone. Common catechol oxidase inhibitors, salicylhydroxamic acid and p-coumaric acid, inhibit the oxidase activity. Catechol oxidation activity was also detected in three other catalases tested, from Aspergillus niger, human erythrocyte, and bovine liver, suggesting that this dual catalase-phenol oxidase activity may be a common feature of catalases. PMID:18369615

Sutay Kocabas, Didem; Bakir, Ufuk; Phillips, Simon E V; McPherson, Michael J; Ogel, Zumrut B

2008-03-28

49

Catechol concentrations in the hemolymph of the scallop, Placopecten magellanicus.  

PubMed

Catecholamines have previously been detected in numerous tissues and are thought to control a wide variety of physiological functions in bivalve molluscs. In the present study, alumina extraction and high-performance liquid chromatography reveal the presence of significant concentrations of 3,4-dihydroxyphenylalanine (DOPA), dopamine, and 3,4-dihydroxyphenylacetic acid (DOPAC) in the hemolymph of the sea scallop, Placopecten magellanicus. The concentration of dopamine in the hemolymph averaged 223.8 ng/ml, (+/-48.4, SEM), equivalent to 10(-7) to 10(-6) M. Neither epinephrine nor norepinephrine was reliably detected in significant quantities. Previous studies have demonstrated physiological responses to dopamine with thresholds of 10(-9) to 10(-6) M, thus suggesting that this catecholamine may have an endocrine function. Furthermore, monitoring hemolymph concentrations of catechols might provide a sensitive measure of the physiological status of bivalves. For example, drugs known to affect catechol concentrations in other tissues also effect hemolymph levels. Administration of monoamine oxidase inhibitors such as pargyline, deprenyl, and clorgyline at 10(-4) M for 1 day of incubation followed by a 2-day wash resulted in decreased hemolymph concentrations of DOPAC and increased concentrations of its precursors, DOPA and dopamine. Incubation in 10(-4) M 3,5-dinitrocatechol, a catecholamine-O-methyl transferase blocker, for 1 day followed by a 2-day wash significantly increased the concentration of dopamine and DOPAC in the hemolymph. Scallops incubated in 10(-5) M alpha-methyl-p-tyrosine, a blocker of tyrosine hydroxylase, for 1 day followed by a 3-day wash in artificial seawater had significantly reduced concentrations of DOPA, dopamine, and DOPAC in the hemolymph. In addition to responding to pharmacological agents, dopamine levels also decreased significantly following thermal induction of spawning, thus suggesting that hemolymph concentrations of catechols might provide indices of reproductive activity and/or stress. PMID:10753566

Pani, A K; Croll, R P

2000-04-01

50

A new boronic acid based fluorescent reporter for catechol.  

PubMed

Catechol skeleton widely exists in natural products and bioactive substances. Fluorescent reporters which could recognize catechol are very promising for the construction of chemosensors to detect catechol and its derivatives in biological environment. Herein, we reported a novel catechol reporter, 2-(4-boronophenyl)quinoline-4-carboxylic acid, which exhibits significant fluorescent property changes upon binding catechol containing molecules in an aqueous solution. PMID:23079526

Wu, Zhongyu; Li, Minyong; Fang, Hao; Wang, Binghe

2012-09-27

51

Endogenous catechol thioethers may be pro-oxidant or antioxidant  

Microsoft Academic Search

Increased catechol thioether formation is associated with Parkinson’s disease. In this study, we examined whether catechol thioethers, having a lower oxidation potential than their parent catechols, would cause greater oxidative damage than their parent catechols. We synthesized 5?-S-glutathionyl, cysteinyl, and N-acetylcysteinyl derivatives of dopamine and dopac, encompassing the known catechol thioethers of the mercapturate pathway. Cyclic voltametry studies showed that

Matthew J Picklo; Venkataraman Amarnath; Doyle G Graham; Thomas J Montine

1999-01-01

52

An efficient method for visualization and growth of fluorescent Xanthomonas oryzae pv. oryzae in planta  

Microsoft Academic Search

BACKGROUND: Xanthomonas oryzae pv. oryzae, the causal agent of bacterial blight disease, is a serious pathogen of rice. Here we describe a fluorescent marker system to study virulence and pathogenicity of X. oryzae pv. oryzae. RESULTS: A fluorescent X. oryzae pv. oryzae Philippine race 6 strain expressing green fluorescent protein (GFP) (PXO99GFP) was generated using the gfp gene under the

Sang-Wook Han; Chang-Jin Park; Sang-Won Lee; Pamela C Ronald

2008-01-01

53

Enzymatic O-methylation of catechols and catecholamines  

Microsoft Academic Search

The reactivity of a number of catechols and catecholamines with regard to the enzymaticO-methylation by catechol-O-methyltransferase (comt) was studied. The reaction was carried out in a vial at a temperature of 37°C, the vial contained a certain concentration of one catechol(amine), catechol-O-methyltransferase (the enzyme),S-adenosylmethionine (the methyldonor), MgCl2 (a cofactor) and buffer pH=7.85. After certain time intervals samples were taken, the

M. T. I. W. Schüsler-Van Hees; G. M. J. Beijersbergen Van Henegouwen

1982-01-01

54

Aluminum complexation by catechol as determined by ultraviolet spectrophotometry  

Microsoft Academic Search

Methods of ultraviolet (UV) spectrophotometry were used to determine the stoichiometry and association constant for the Al-catechol complex from pH 3.8 to 4.6. Job's method of continuous variation indicated the Al-catechol complex had a 1:1 stoichiometry in the pH range studied. Aluminum titrations of catechol and pH titrations of catechol plus Al resulted in a shift in the UV spectra

Frank J. Sikora; Murray B. McBride

1989-01-01

55

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.

Marie, Helene; Barrere, Amelie; Schoentstein, Frederique; Chavanne, Marie-Helene; Grosgogeat, Brigitte; Mora, Laurence

2012-01-01

56

In vitro and in vivo percutaneous absorption of catechol  

Microsoft Academic Search

The Cosmetic Ingredient Review Expert Panel found insufficient data to conclude that catechol could be used safely in permanent hair dye products. Information was lacking on the extent of oxidation and skin absorption of remaining catechol. In vitro percutaneous absorption studies were conducted in human and rat skin using a consumer permanent hair dye spiked with 0.6% catechol. A 30-min

C. T Jung; R. R Wickett; P. B Desai; R. L Bronaugh

2003-01-01

57

Removal of arsenic compounds from spent catecholated polymer  

Microsoft Academic Search

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: treating said spent catecholated polystyrene,

Fish

1985-01-01

58

Removal of arsenic compounds from spent catecholated polymer  

Microsoft Academic Search

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

Fish; Richard H

1985-01-01

59

Catecholate Siderophores Protect Bacteria from Pyochelin Toxicity  

PubMed Central

Background Bacteria produce small molecule iron chelators, known as siderophores, to facilitate the acquisition of iron from the environment. The synthesis of more than one siderophore and the production of multiple siderophore uptake systems by a single bacterial species are common place. The selective advantages conferred by the multiplicity of siderophore synthesis remains poorly understood. However, there is growing evidence suggesting that siderophores may have other physiological roles besides their involvement in iron acquisition. Methods and Principal Findings Here we provide the first report that pyochelin displays antibiotic activity against some bacterial strains. Observation of differential sensitivity to pyochelin against a panel of bacteria provided the first indications that catecholate siderophores, produced by some bacteria, may have roles other than iron acquisition. A pattern emerged where only those strains able to make catecholate-type siderophores were resistant to pyochelin. We were able to associate pyochelin resistance to catecholate production by showing that pyochelin-resistant Escherichia coli became sensitive when biosynthesis of its catecholate siderophore enterobactin was impaired. As expected, supplementation with enterobactin conferred pyochelin resistance to the entE mutant. We observed that pyochelin-induced growth inhibition was independent of iron availability and was prevented by addition of the reducing agent ascorbic acid or by anaerobic incubation. Addition of pyochelin to E. coli increased the levels of reactive oxygen species (ROS) while addition of ascorbic acid or enterobactin reduced them. In contrast, addition of the carboxylate-type siderophore, citrate, did not prevent pyochelin-induced ROS increases and their associated toxicity. Conclusions We have shown that the catecholate siderophore enterobactin protects E. coli against the toxic effects of pyochelin by reducing ROS. Thus, it appears that catecholate siderophores can behave as protectors of oxidative stress. These results support the idea that siderophores can have physiological roles aside from those in iron acquisition.

Adler, Conrado; Corbalan, Natalia S.; Seyedsayamdost, Mohammad R.; Pomares, Maria Fernanda; de Cristobal, Ricardo E.; Clardy, Jon; Kolter, Roberto; Vincent, Paula A.

2012-01-01

60

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

61

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

62

Catechol degradation by immobilized Rhizobium sp.  

PubMed

Entrapped cells of Rhizobium sp. isolated from Lablab purpureus in calcium alginate degraded catechol (1,2-dihydroxybenzene) compared with the free cells. Agitation enhanced its rapid degradation. The versatility of Rhizobium sp. to degrade phenolic substances can be exploited in biotechnological application. PMID:2042401

Gajendiran, N; Mahadevan, A

1991-01-01

63

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.

Shivprasad, Shailaja; Page, William J.

1989-01-01

64

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

65

Molecular mechanisms controlling the rate and specificity of catechol O-methylation by human soluble catechol O-methyltransferase.  

PubMed

Molecular mechanisms determining the turn-over rate and specificity of catechol O-methylation were studied by combining enzyme kinetic measurements, computational modeling of substrate properties and fitting ligands in a 3D model of the active site of the enzyme. Enzyme kinetic measurements were carried out for 46 compounds, including most clinically used catechol drugs, by using recombinant human soluble catechol O-methyltransferase (COMT). The most important mechanism decreasing the turnover rate and increasing affinity was the electron withdrawing effect of substituents. Several other mechanisms by which substituents affected reactivity and affinity were identified. Highest turnover rates were determined for unsubstituted catechol and pyrogallol. Pyrogallol derivatives generally seemed to be more specific substrates than catechols. Catecholestrogens were the most specific endogenous substrates, whereas catecholamines were rather poor substrates. Among the catechol drugs used in the L-DOPA treatment of Parkinson's disease, the COMT inhibitors entacapone and tolcapone were not methylated, whereas the DOPA decarboxylase inhibitor benserazide was 15 times more specific substrate than L-DOPA, the target of COMT inhibition. The structure-activity relationships found allow the prediction of reactivity, affinity, and specificity with useful accuracy for catechols with a wide range of structures and properties. The knowledge can be used in the evaluation of metabolic interactions of endogenous catechols, drugs and dietary catechols, and in the designing of drugs with the catechol pharmacophore. PMID:11160877

Lautala, P; Ulmanen, I; Taskinen, J

2001-02-01

66

Catechol metabolites of the mycotoxin zearalenone are poor substrates but potent inhibitors of catechol-O-methyltransferase.  

PubMed

The mycotoxin zearalenone (ZEN) elicits estrogenic effects and is biotransformed to two catechol metabolites, in analogy to the endogenous steroidal estrogen 17ß-estradiol (E2). Previous studies have shown that the catechol metabolites of ZEN have about the same potency to induce oxidative DNA damage as the catechol metabolites of E2, but are less efficiently converted to their methyl ethers by human hepatic catechol-O-methyltransferase (COMT). Here, we report that the two catechol metabolites of ZEN, i.e. 13-hydroxy-ZEN and 15-hydroxy-ZEN, are not only poor substrates of human COMT but are also able to strongly inhibit the O-methylation of 2-hydroxy-E2, the major catechol metabolite of E2. 15-Hydroxy-ZEN acts as a non-competitive inhibitor and is about ten times more potent than 13-hydroxy-ZEN, which is an uncompetitive inhibitor of COMT. The catechol metabolites of ZEN were also shown to inhibit the O-methylation of 2-hydroxy-E2 by hepatic COMT from mouse, rat, steer and piglet, although to a lesser extent than observed with human COMT. The powerful inhibitory effect of catechol metabolites of ZEN on COMT may have implications for the tumorigenic activity of E2, because catechol metabolites of E2 elicit genotoxic effects, and their impaired O-methylation may increase the tumorigenicity of steroidal estrogens. PMID:23558779

Pfeiffer, Erika; Wefers, Daniel; Hildebrand, Andreas A; Fleck, Stefanie C; Metzler, Manfred

2013-04-05

67

An archetypical extradiol-cleaving catecholic dioxygenase: the crystal structure of catechol 2,3-dioxygenase (metapyrocatechase) from Pseudomonas putida mt-2  

Microsoft Academic Search

Background: Catechol dioxygenases catalyze the ring cleavage of catechol and its derivatives in either an intradiol or extradiol manner. These enzymes have a key role in the degradation of aromatic molecules in the environment by soil bacteria. Catechol 2,3-dioxygenase catalyzes the incorporation of dioxygen into catechol and the extradiol ring cleavage to form 2-hydroxymuconate semialdehyde. Catechol 2,3-dioxygenase (metapyrocatechase, MPC) from

Akiko Kita; Shin-ichi Kita; Ikuhide Fujisawa; Koji Inaka; Tetsuo Ishida; Kihachiro Horiike; Mitsuhiro Nozaki; Kunio Miki

1999-01-01

68

Interaction of catechol and non-catechol substrates with externally or internally facing dopamine transporters  

PubMed Central

Our previous work suggested that collapsing the Na+ gradient and membrane potential converts the dopamine (DA) transporter (DAT) to an inward-facing conformation with a different substrate binding profile. Here, DAT expressing HEK 293 cells were permeabilized with digitonin, disrupting ion/voltage gradients and allowing passage of DAT substrates. The potency of p-tyramine and other non-catechols (d-amphetamine, ?-phenethylamine, MPP+) in inhibiting cocaine analog binding to DAT in digitonin-treated cells was markedly weakened to a level similar to that observed in cell-free membranes. In contrast, the potency of DA and another catechol, norepinephrine, was not significantly changed by the same treatment, whereas epinephrine showed only a modest reduction. These findings suggest catechol substrates interact symmetrically with both sides of DAT and non-catechol substrates favor binding to outward-facing transporter. In the cocaine analog binding assay, the mutant W84L displayed enhanced intrinsic binding affinity for substrates in interacting with both outward- and inward- facing states; D313N showed WT-like symmetric binding; but D267L and E428Q showed an apparent improvement in the permeation pathway from the external face towards the substrate site. Thus, the structure of both substrate and transporter play a role in the sidedness and mode of interaction between them.

Liang, Ying-Jian; Zhen, Juan; Chen, Nianhang; Reith, Maarten E.A.

2009-01-01

69

Partial characterization of polyphenol oxidase activity in raspberry fruits.  

PubMed

A partial characterization of polyphenol oxidase (PPO) activity in raspberry fruits is described. Two early cultivars harvested in May/June (Heritage and Autumm Bliss) and two late cultivars harvested in October-November (Ceva and Rubi) were analyzed for PPO activity. Stable and highly active PPO extracts were obtained using insoluble poly(vinylpyrrolidone) (PVP) and Triton X-100 in sodium phosphate, pH 7.0 buffer. Polyacrylamide gel electrophoresis of raspberry extracts under nondenaturing conditions resolved in one band (R(f)()(1) = 0.25). Raspberry PPO activity has pH optima of 8.0 and 5.5, both with catechol (0.1 M). Maximum activity was with D-catechin (catecholase activity), followed by p-coumaric acid (cresolase activity). Heritage raspberry also showed PPO activity toward 4-methylcatechol. Ceva and Autumm Bliss raspberries showed the higher PPO activity using catechol as substrate. PMID:10552767

González, E M; de Ancos, B; Cano, M P

1999-10-01

70

Inoculation with Xanthomonas oryzae pv. oryzae induces thylakoid membrane association of Rubisco activase in Oryza meyeriana.  

PubMed

Oryza meyeriana is a wild species of rice with high resistance to Xanthomonas oryzae pv. oryzae (Xoo), but the resistance mechanism is poorly understood. Protein gel blot analysis and immuno-gold electron microscopy showed that Xoo infection induced an association of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activase (RCA) with the thylakoid membrane in O. meyeriana, which led to considerable decline in the initial activity and the activation state of Rubisco. In susceptible cultivated rice, RCA remained in the chloroplast stroma. RCA may play a role in resistance to Xoo in O. meyeriana that differs from its well-known role in activating Rubisco, perhaps by protecting the thylakoid membrane against damage from Xoo. PMID:21501886

Yang, Yong; Yu, Chu-Lang; Wang, Xu-Ming; Yan, Cheng-Qi; Cheng, Ye; Chen, Jian-Ping

2011-04-17

71

Peach polyphenol oxidase inhibition by 𝛃-cyclodextrin and 4-hexylresorcinol is substrate dependent La inhibición de la polifenoloxidasa de durazno por 𝛃-ciclodextrina y 4-hexilresorcinol es dependiente del sustrato  

Microsoft Academic Search

Polyphenol oxidase (PPO) was extracted from whole peaches and its catecholase activity was studied spectrophotometrically against three substrates: catechol (Cat), 4-methyl catechol (4MC), and chlorogenic acid (CA). Peach PPO specificity was: CA > 4MC ? Cat. 4-hexylresorcinol (4HR, 0.5 mM) inhibited oxidation of Cat and CA by 50% or more, at all substrate concentrations, but had no effect on the oxidation of 4MC,

Laura A. de la Rosa; Gilberto Mercado-Mercado; Joaquín Rodrigo-García; Gustavo A. González-Aguilar; Emilio Alvarez-Parrilla

2010-01-01

72

Characterization of cDNAs encoding putative laccase-like multicopper oxidases and developmental expression in the tobacco hornworm, Manduca sexta, and the malaria mosquito, Anopheles gambiae  

Microsoft Academic Search

Laccase (EC 1.10.3.2) is an enzyme with p-diphenol oxidase activity that is a member of a group of proteins collectively known as multicopper, or blue copper, oxidases. Laccase is hypothesized to play an important role in insect cuticle sclerotization by oxidizing catechols in the cuticle to their corresponding quinones, which then catalyze protein cross-linking reactions. To facilitate studies of the

Neal T. Dittmer; Richard J. Suderman; Haobo Jiang; Yu-Cheng Zhu; Maureen J. Gorman; Karl J. Kramer; Michael R. Kanost

2004-01-01

73

Molecular characterization of the avrXa7 locus from Xanthomonas oryzae pv. oryzae field isolates  

Microsoft Academic Search

The effector gene avrXa7 from Xanthomonas oryzae pv. oryzae has avirulence function in rice with the Xa7 resistance gene and confers pathogenic fitness (aggressiveness). Field strains of X. oryzae pv. oryzae displayed a diversity of phenotypes on rice ranging from complete to partial loss of these functions. To understand the molecular basis for variation in avrXa7 function, we sequenced the

Grisel Ponciano; Kimberly Webb; Jianfa Bai; Casiana Vera Cruz; Jan E. Leach

2004-01-01

74

Polyphenol oxidase activity, phenolic acid composition and browning in cashew apple ( Anacardium occidentale, L.) after processing  

Microsoft Academic Search

This study describes the extraction and characterisation of cashew apple polyphenol oxidase (PPO) and the effect of wounding on cashew apple phenolic acid composition, PPO activity and fruit browning. Purification factor was 59 at 95% (NH4)2SO4 saturation. For PPO activity, the optimal substrate was catechol and the optimum pH was 6.5. PPO Km and Vmax values were 18.8mM and 13.6Umin?1ml?1,

Christiane Queiroz; Antonio Jorge Ribeiro da Silva; Maria Lúcia Mendes Lopes; Eliane Fialho; Vera Lúcia Valente-Mesquita

2011-01-01

75

Decolorization of the Textile Dyes Using Purified Banana Pulp Polyphenol Oxidase  

Microsoft Academic Search

Polyphenol oxidase (PPO) purified using DEAE-cellulose and Biogel P-100 column chromatography from banana pulp showed 12.72-fold activity and 2.49% yield. The optimum temperature and pH were found to be 30°C and 7.0, respectively for its activity. Catechol was found to be a suitable substrate for banana pulp PPO that showed Vmax, 0.041 mM min and Km, 1.6 mM. The enzyme

Umesh U. Jadhav; Vishal V. Dawkar; Mital U. Jadhav; Sanjay P. Govindwar

2011-01-01

76

Bioinspired catecholic copolymers for antifouling surface coatings.  

PubMed

We report here a synthetic approach to prepare poly(methyl methacrylate)-polydopamine diblock (PMMA-PDA) and triblock (PDA-PMMA-PDA) copolymers combining mussel-inspired catecholic oxidative chemistry and atom transfer radical polymerization (ATRP). These copolymers display very good solubility in a range of organic solvents and also a broad band photo absorbance that increases with increasing PDA content in the copolymer. Spin-cast thin films of the copolymer were stable in water and showed a sharp reduction (by up to 50%) in protein adsorption compared to those of neat PMMA. Also the peak decomposition temperature of the copolymers was up to 43°C higher than neat PMMA. The enhanced solvent processability, thermal stability and low protein adsorption characteristics of this copolymer makes it attractive for variety of applications including antifouling coatings on large surfaces such as ship hulls, buoys, and wave energy converters. PMID:23544666

Cho, Joon Hee; Shanmuganathan, Kadhiravan; Ellison, Christopher J

2013-04-24

77

Hydroquinone\\/catechol-bearing polyacrylic acid: redox polymer  

Microsoft Academic Search

Polyacrylic acid (PAA) was functionalized with a hydroquinone\\/catechol under the reaction conditions of Minisci. Optimum conditions for maximum functionalization (degree of substitution of 35%) were achieved under the following conditions: [benzoquinone]\\/[PAA]=1; reaction time, 6 h; temperature, 75 °C; nitrogen atmosphere. Redox properties of hydroquinone\\/catechol-modified PAA (PAA-HQ) were evaluated by their mid-potentials potentiometrically estimated to be 863 mV at 20 °C.

Saâd Moulay; Razika Mehdaoui

2004-01-01

78

Reaction conditions for laccase catalyzed polymerization of catechol  

Microsoft Academic Search

Poly(catechol) was synthesized in batch runs with laccase from Trametes versicolor (ATCC 200801). The polymerization reaction was conducted in a closed, temperature controlled system containing acetone and sodium acetate buffer for pH control. The effects of the solvent mixture, monomer (catechol), enzyme, medium pH and temperature on the polymerization rate were investigated with respect to initial reaction conditions and depletion

Nahit Akta?; Abdurrahman Tanyolaç

2003-01-01

79

Chemisorption of catechol on gibbsite, boehmite, and noncrystalline alumina surfaces  

SciTech Connect

The mechanism of bonding of catechol and related phenolic compounds on aluminum oxides was elucidated from sorption behavior in the presence of competing adsorbates and the nature of the infrared spectra of the surface-bound molecules. The surfaces demonstrated a high degree of selectivity toward catechol, adsorbing the molecule in the presence of a large excess of chloride. Phosphate competed effectively with catechol for sorption sites while acetate did not. Dispersive and Fourier transform infrared spectroscopy verified that catechol bound on the aluminum oxide surfaces was chemically perturbed in much the same manner as catechol chelated by Al/sup 3 +/, suggesting that the dominant sorption process involved the formation of a 1:1 bidentate complex with surface Al. The mechanisms of bonding was similar for all the aluminum oxides, but the dominant crystal surfaces of the crystalline oxides were unreactive toward catechol, and adsorption was attributed to -AlOH groups situated on edge faces. As a result, the noncrystalline oxide was more reactive per unit of surface area than the crystalline minerals boehmite and gibbsite.

McBride, M.B.; Wesselink, L.G.

1988-06-01

80

Surfactant degradation by a catechol-driven Fenton reaction.  

PubMed

The addition of 0.5mM catechol is shown to accelerate the degradation and mineralization of the anionic surfactant DowFax 2A1 (sodium dodecyldiphenyloxide disulfonate) under conventional Fenton reaction conditions (Fe(II) plus H(2)O(2) at pH 3). The catalytic effect causes a 3-fold increase in the initial rate (up to ca. 20 min) of conversion of the surfactant to oxidation products (apparent first-order rate constants of 0.021 and 0.061 min(-1) in the absence and presence of catechol, respectively). Although this catalytic rate increase persists for a certain amount of time after complete disappearance of catechol itself (ca. 8 min), the reaction rate begins to decline slowly after the initial 20 min towards that observed in the absence of added catechol. Total organic carbon (TOC) measurements of net mineralization and cyclic voltammetric and high performance liquid chromatographic (HPLC) measurements of the initial rate of reaction of catechol and the surfactant provide insight into the role of catechol in promoting the degradation of the surfactant and of degradation products as the eventual inhibitors of the Fenton reaction. PMID:20181425

Zanta, Carmem Lúcia P S; Friedrich, Leidi C; Machulek, Amilcar; Higa, Karen M; Quina, Frank H

2010-01-18

81

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

82

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

2013-09-05

83

Toxic tetrapyrrole accumulation in protoporphyrinogen IX oxidase-overexpressing transgenic rice plants  

Microsoft Academic Search

We generated transgenic rice plants (Oryza sativa cv. Dongjin) over-expressing human protoporphyrinogen IX oxidase (PPO) with the aim to increase mitochondrial PPO activity\\u000a and confer herbicide resistance (Lee et al., Pestic Biochem Physiol 80:65–74, 2004). The transgenic plants showed during further\\u000a leaf development the formation of severe necrotic spots and growth retardation. Several experiments were performed to examine\\u000a the reasons for

Sunyo Jung; Hye-Jung Lee; Yonghyuk Lee; Kiyoon Kang; Young Soon Kim; Bernhard Grimm; Kyoungwhan Back

2008-01-01

84

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

85

Application of electrosynthesized poly(aniline- co- p-aminophenol) as a catechol sensor  

Microsoft Academic Search

Poly(aniline-co-p-aminophenol) (copolymer) film was used as a sensor to determine the presence of catechol, taking advantage of the ability of the film to effectively catalyze the oxidation of catechol. The copolymer served as an electron transfer mediator between the electrode surface and catechol in the solution. The response current of the catechol sensor depended on the applied potential, pH and

Chuanxiang Chen; Cheng Sun; Yuhua Gao

2009-01-01

86

Antioxidant activity and enzyme inhibition of phenolic acids from fermented rice bran with fungus Rizhopus oryzae.  

PubMed

The solid-state fermentation (SSF) has been employed as a form making available a higher content of functional compounds from agroindustrial wastes. In this work, the effect of SSF with the Rhizopus oryzae fungus on the phenolic acid content of rice bran was studied. Phenolic extracts derived from rice bran and fermented rice bran were evaluated for their ability to reduce free radical 1,1-diphenyl-2-picrihidrazil (DPPH) and for the ability to inhibit the enzymes peroxidase and polyphenol oxidase. The phenolic compound content increased by more than two times with fermentation. A change in the content of phenolic acids was observed, with ferulic acid presenting the greatest increase with the fermentation, starting from 33mg/g in rice bran and reaching 765mg/g in the fermented bran. The phenolic extracts showed an inhibition potential for DPPH and for the peroxidase enzyme, however did not inhibit the polyphenol oxidase enzyme. PMID:24176356

Schmidt, Cristiano G; Gonçalves, Letícia M; Prietto, Luciana; Hackbart, Helen S; Furlong, Eliana B

2013-09-23

87

Oxidases and related redox systems  

SciTech Connect

This book contains the proceedings of a symposium on oxidases and related redoxsystems. Topics covered include: Oxidases and related redoxsystems, Flavoprotein oxidases and oxygenases, Peroxidases, and Cytochrome P-450 and related proteins.

King, T.E. (Inst. for Structural and Functional Studies, Univ. City Science Center, Philadelphia, PA (US)); Mason, H.S. (Dept. of Biochemistry, Oregon Health Sciences Univ., Portland, OR (US)); Morrison, M. (Saint Jude Children's Hospital, Memphis, TN (USA). Dept. of Biochemical and Chemical Pharmacology)

1988-01-01

88

Removal of arsenic compounds from spent catecholated polymer  

SciTech Connect

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: treating said spent catecholated polystyrene, at a temperature in the range of about 20/sup 0/ to 100/sup 0/ 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 is in two steps.

Fish, R. H.

1985-11-12

89

Antimicrobial activity of catechol and pyrogallol as allelochemicals.  

PubMed

Catechol and pyrogallol are allelochemicals which belong to phenolic compounds synthesized in plants. Their antimicrobial activities were investigated on three bacteria (Pseudomonas putida, Pseudomonas pyocyanea, Corynebacterium xerosis) and two fungi (Fusarium oxysporum, Penicillium italicum) phytopathogenic species as test organisms using the disc diffusion method. Both catechol and pyrogallol were found to have antibacterial effects on all the bacteria used in the study at 5 and 10 mM concentrations. Catechol has also been found to have an antifungal effect on the fungi used in the study, whereas no antifungal effects of pyrogallol were observed. The most sensitive species among the bacteria was P. putida which was inhibited by the allelochemicals even at 1 mM concentration. PMID:17137106

Kocaçali?kan, Ismail; Talan, Ismet; Terzi, Irfan

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

Polyploid evolution in Oryza officinalis complex of the genus Oryza  

PubMed Central

Background Polyploidization is a prominent process in plant evolution, whereas the mechanism and tempo-spatial process remained poorly understood. Oryza officinalis complex, a polyploid complex in the genus Oryza, could exemplify the issues not only for it covering a variety of ploidy levels, but also for the pantropical geographic pattern of its polyploids in Asia, Africa, Australia and Americas, in which a pivotal genome, the C-genome, witnessed all the polyploidization process. Results Tracing the C-genome evolutionary history in Oryza officinalis complex, this study revealed the genomic relationships, polyploid forming and diverging times, and diploidization process, based on phylogeny, molecular-clock analyses and fluorescent in situ hybridization using genome-specific probes. Results showed that C-genome split with B-genome at ca. 4.8 Mya, followed by a series of speciation of C-genome diploids (ca. 1.8-0.9 Mya), which then partook in successive polyploidization events, forming CCDD tetraploids in ca. 0.9 Mya, and stepwise forming BBCC tetraploids between ca. 0.3-0.6 Mya. Inter-genomic translocations between B- and C-genomes were identified in BBCC tetraploid, O. punctata. Distinct FISH (fluorescent in situ hybridization) patterns among three CCDD species were visualized by C-genome-specific probes. B-genome was modified before forming the BBCC tetraploid, O. malampuzhaensis. Conclusion C-genome, shared by all polyploid species in the complex, had experienced different evolutionary history particularly after polyploidization, e.g., inter-genomic exchange in BBCC and genomic invasion in CCDD tetraploids. It diverged from B-genome at 4.8 Mya, then participated in the tetraploid formation spanning from 0.9 to 0.3 Mya, and spread into tropics of the disjunct continents by transcontinentally long-distance dispersal, instead of vicariance, as proposed by this study, given that the continental splitting was much earlier than the C-genome species radiation. We also find reliable evidence indicated that an extinct BB diploid species in Asia was presumptively the direct genomic donor of their sympatric tetraploids.

Wang, Baosheng; Ding, Zhuoya; Liu, Wei; Pan, Jin; Li, Changbao; Ge, Song; Zhang, Daming

2009-01-01

92

Catechol derivatives of Group 4 and 5 compounds  

Microsoft Academic Search

The structural modifications of Group 4 and 5 metal alkoxides using the bidentate catechol (C6H3(OH)2-1,3=cat-H2) have been investigated. From the reaction of [Ti(?-ONep)(ONep)3]2 (ONep=OCH2CMe3), [Zr(?-OPri)(ONep)3·HONep]2(OPri=OCHMe2), Hf(OEt)4 (OEt=OCH2Me) with 2 equivalents, and M(OEt)5 (M=Nb or Ta) with 3 equiv. of cat-H2 in pyridine (py), the complete removal of alkoxide ligands and isolation of the first neutral catechol derivatives of the Group

Timothy J. Boyle; Louis J. Tribby; Todd M. Alam; Scott D. Bunge; Gregory P. Holland

2005-01-01

93

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

PubMed

The mononuclear [Mn(6'Me(2)indH)(H(2)O)(2)(CH(3)CN)](ClO(4))(2) (6'Me(2)indH: 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-DTBCH(2)) 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 measurements revealed first-order dependence on the catalyst and dioxygen concentration and saturation type behavior with respect to the corresponding substrate. It was also found that the added triethylamine in both systems accelerates the reaction. PMID:18222003

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

2007-12-07

94

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

95

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

96

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

97

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

98

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

99

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

100

Hybrids of rice ( Oryza sativa L.) and wild Oryza species obtained by cell fusion  

Microsoft Academic Search

Cell fusion was used to obtain hybrid plants of rice (Oryza sativa L.) and four wild Oryza species, O. officinalis, O. eichingeri, O. brachyantha, and O. perrieri, to incorporate useful traits of the latter species into rice. A total of 250 mature hybrid plants were obtained by electrofusion and nurse culture methods. The hybrid nature of these plants was confirmed

Yasuyuki Hayashi; Junko Kyozuka; Ko Shimamoto

1988-01-01

101

Involvement of catalase in bacterial Blight disease development of rice caused by Xanthomonas oryzae pv. oryzae  

Microsoft Academic Search

We investigated the role of catalase in determining the virulence of Xanthomonas oryzae pv. oryzae isolates and the reaction of different rice cultivars to virulent isolates. Catalase, being an antioxidant enzyme, plays a major role in combating the toxic effect of reactive oxygen species (ROS) in plant cells. Among the 11 isolates studied, a variable level of catalase activity and

M. S. Choodamani; P. Hariprasad; M. K. Sateesh; S. Umesha

2009-01-01

102

Structural conservation of the hrp gene cluster in Xanthomons oryzae pv. oryzae  

Microsoft Academic Search

The clustered hrp genes encoding the type III secretion system in the Japanese strains MAFF301237 and MAFF311018 of Xanthomonas oryzae pv. oryzae were sequenced and compared. The strains differ in their pathogenicity, location, and year of isolation. A 30-kbp sequence comprising 29 open reading frames (ORFs) was identical in its structural arrangement in both strains but differed from X. campestris

Takashi Oku; Koji Tanaka; Motohiro Iwamoto; Yasuhiro Inoue; Hirokazu Ochiai; Hisatoshi Kaku; Seiji Tsuge; Kazunori Tsuno

2004-01-01

103

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

2012-03-30

104

Influence of subchronic administration of catechol estrogens on the formation of reactive oxygen species in rat liver microsomes.  

PubMed

Metabolic pathways of estrogens are the formation of catechol estrogens (CE; 2- and 4-hydroxy-estrogens), redox cycling of CE and free radical generation, mediated through cytochrome P450 (P450) oxidase/reductase activity. In previous investigations subchronic administration of estrogens showed prooxidative and antioxidative activities in rat liver microsomes (BARTH et al. 1999). To find out whether or not catechol metabolites are responsible for prooxidative activity, we checked 2- and 4-hydroxy-estradiol (2OH-E2 and 4OH-E2) and the non-catechol metabolite 6alpha-hydroxy-estradiol (6alpha-OH-E2) for formation of reactive oxygen species in liver microsomes of 30-day-old male Wistar rats after 5 days treatment (1, 10 mg/kg b. wt. orally, once a day). The results were compared with those after treatment of the rats with estradiol (E2), estradiol valerate (E2V) and ethinylestradiol (EE2). In liver homogenates glutathione and lipid peroxides were determined, in microsomes NADPH-Fe++-stimulated lipid peroxidation (LPO), H2O2 generation and lucigenin (LUC) and luminol (LUM) amplified chemiluminescence (CL) were investigated. In liver 9000 x g supernatants monooxygenase activities were measured. The two catechol estrogens did not show any antioxidative activity, whereas 6alpha-OH-E2 significantly diminished lipid peroxides in the liver as well as LPO and LUM-CL in liver microsomes. Among estrogens, only EE2 showed antioxidative activity. Both CE inhibited ethoxycoumarin O-deethylation. Peroxidative activity as enhanced LUC-CL was found after 2OH-E2 (1 mg/kg b.wt.) and E2, but 10 times higher doses of both CE did not change LUC-CL. Microsomal H2O2 generation was enhanced by E2, E2V and both CE, not by 6alpha-OH-E2. The lower level of H2O2 enhancement caused by CE in comparison to E2 and E2V together with unchanged LUC-CL after high CE doses did not unequivocally prove the CE to be mainly responsible for the prooxidative activities of E2 and E2V in liver microsomes, at least in 30-day-old male rats. Unchanged GSH in the liver after CE administration supports this hypothesis. PMID:10987185

Barth, A; Müller, D; Karge, E; Klinger, W

2000-08-01

105

Iron-Binding Catechols and Virulence in Escherichia coli  

PubMed Central

Previous work suggested that virulent bacteria, which can grow rapidly in serum, must possess a specific mechanism for removing iron from its transferrin complex. Two strains of Escherichia coli were examined with this in mind. Strain O141, which showed inoculum-dependent growth in serum and multiplied in the mouse peritoneum, secreted iron-binding catechols into both synthetic medium and serum. One of these compounds has an association constant for iron similar to that of transferrin. Both transferrin and ethylenediamine-di-o-hydroxyphenyl acetic acid (EDDA), which have very high affinities for ferric iron, induced catechol synthesis in growing cultures of strain O111. This organism was inhibited by normal horse serum. Further work showed that traces of specific antibody inhibited catechol synthesis by O111 exposed to EDDA; therefore, the existence of this inhibitory process means that the organism can no longer obtain Fe3+, which all remains bound to transferrin in serum. In vivo, the inhibition of O111 is similar to that produced by serum in vitro. Neither phagocytosis nor killing by complement appeared to be of any significance during the first 4 h of the infections. Significantly, the purified catechol was capable of abolishing bacteriostasis in vivo. Since these results show that the production of iron-binding catechols is essential for rapid bacterial growth both in vitro and in vivo, these compounds should therefore be considered as true virulence factors. Conversely, any interference by the host with the production or activity of these compounds would constitute an important aspect of antibacterial defense. Images

Rogers, Henry J.

1973-01-01

106

Catecholate/salicylate heteropodands: demonstration of a catecholate to salicylate coordination change.  

PubMed

While iron release from enterobactin-mediated iron transport occurs primarily via an esterase that destroys the siderophore, other catechol siderophores that are not susceptible to hydrolysis act as bacterial growth factors. Elucidating the structures of protonated ferric enterobactin may reveal the pathway by which synthetic analogues fulfill bacterial iron requirements. In order to more completely model this potential delivery pathway for ferric iron, as well as to understand the pH dependent structural dynamics of ferric enterobactin, two ligands, (2-hydroxybenzoyl-2-aminoethyl)-bis(2,3-dihydroxybenzoyl-2-aminoethyl)amine (TRENCAMSAM) and (2-hydroxy-3-methoxybenzoyl-2-aminoethyl)-bis(2,3-dihydroxybenzoyl-2- aminoethyl)amine (TRENCAM(3M)SAM), have been synthesized as models for monoprotonated enterobactin. The coordination chemistry of these ligands with Fe3+ and Al3+ has been investigated. Fe[TRENCAMSAM]2- crystallizes in the triclinic space group P1: Z = 1, a = 11.3307(6) A, b = 12.5479(7) A, c = 15.5153(8) A, alpha = 94.513(1) degree, beta = 105.867(1) degree, gamma = 94.332(1) degree. The structure is a two-metal two-ligand dimer supported by mu-oxo bridges from two catecholate moieties. Al[TRENCAMSAM]2- crystallizes in the triclinic space group P1: Z = 2, a = 9.1404(2) A, b = 13.3570(1) A, c = 15.5950(1) A, alpha = 95.711(1) degree, beta = 104.760(1) degree, gamma = 92.603(1) degree. The complex is a monomer with a five-coordinate, square-pyramidal aluminum cation. Al[TRENCAM(3M)SAM]2- crystallizes in the monoclinic space group C2/m: Z = 8, a = 34.244(2) A, b = 11.6206(6) A, c = 21.9890(12) A, beta = 101.478(1) degree. The complex is also a monomer, but with a highly distorted five-coordinate, square-pyramidal aluminum cation coordination sphere. At high pH these complexes do not display a salicylate mode of binding; however, at low pH Al[TRENCAMSAM]2- converts to protonated Al[H3TRENCAMSAM]+, which is a six-coordinate, tris-salicylate complex. Al[H3TRENCAMSAM]+ crystallizes in the triclinic space group P1: Z = 2, a = 11.5475(4) A, b = 12.1681(4) A, c = 12.5094(4) A, alpha = 109.142(1) degree, beta = 104.327(1) degree, gamma = 103.636(1) degree. This is the first catecholamide enterobactin analogue that has been structurally characterized in both a catecholate and salicylate mode of coordination. PMID:11196825

Cohen, S M; Raymond, K N

107

Draft Genome Sequence of Aspergillus oryzae Strain 3.042  

PubMed Central

Aspergillus oryzae is the most important fungus for the traditional fermentation in China and is particularly important in soy sauce fermentation. We report the 36,547,279-bp draft genome sequence of A. oryzae 3.042 and compared it to the published genome sequence of A. oryzae RIB40.

Zhao, Guozhong; Yao, Yunping; Qi, Wei; Wang, Chunling; Hou, Lihua; Zeng, Bin

2012-01-01

108

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

PubMed Central

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.

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

109

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

110

Polyphenol oxidase from yacon roots (Smallanthus sonchifolius).  

PubMed

Polyphenol oxidase (E.C. 1.14.18.1) (PPO) extracted from yacon roots (Smallanthus sonchifolius) was partially purified by ammonium sulfate fractionation and separation on Sephadex G-100. The enzyme had a molecular weight of 45 490+/-3500 Da and Km values of 0.23, 1.14, 1.34, and 5.0 mM for the substrates caffeic acid, chlorogenic acid, 4-methylcatechol, and catechol, respectively. When assayed with resorcinol, DL-DOPA, pyrogallol, protocatechuic, p-coumaric, ferulic, and cinnamic acids, catechin, and quercetin, the PPO showed no activity. The optimum pH varied from 5.0 to 6.6, depending on substrate. PPO activity was inhibited by various phenolic and nonphenolic compounds. p-Coumaric and cinnamic acids showed competitive inhibition, with Ki values of 0.017 and 0.011 mM, respectively, using chlorogenic acid as substrate. Heat inactivation from 60 to 90 degrees C showed the enzyme to be relatively stable at 60-70 degrees C, with progressive inactivation when incubated at 80 and 90 degrees C. The Ea (apparent activation energy) for inactivation was 93.69 kJ mol-1. Sucrose, maltose, glucose, fructose, and trehalose at high concentrations appeared to protect yacon PPO against thermal inactivation at 75 and 80 degrees C. PMID:17316020

Neves, Valdir Augusto; da Silva, Maraiza Aparecida

2007-02-23

111

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

2012-01-12

112

Inhibition of apple polyphenol oxidase activity by sodium chlorite.  

PubMed

Sodium chlorite (SC) was shown to have strong efficacy both as a sanitizer to reduce microbial growth on produce and as a browning inhibitor on fresh-cut apples in previous experiments. This study was undertaken to investigate the inhibitory effect of SC on polyphenol oxidase (PPO) and the associated mechanisms. The experiment showed that SC had a strong inhibition of apple PPO. The extent of inhibition was influenced by SC concentration and pH. Inhibition was most prominent at pH 4.5, at which approximately 30% of enzyme activity was lost in the presence of 10 mM SC, followed closely by that at pH 4.0 with a 26% reduction in PPO activity. The inhibition mode was determined using Dixon and Lineweaver-Burk plots, which established SC to be a mixed inhibitor of apple PPO for the oxidation of catechol. Preincubation of PPO with 8 mM SC for 8 min caused a maximum of 46% activity reduction compared to noninhibited control. However, preincubation of SC with catechol for 8 min resulted in no additional loss of PPO activity. These findings provide further evidence that the inhibition of PPO activity by SC is due to the inhibition of the enzyme itself rather than removal of the substrate. PMID:19127746

Lu, Shengmin; Luo, Yaguang; Feng, Hao

2006-05-17

113

Crystallization and preliminary X-ray analysis of formate oxidase, an enzyme of the glucose-methanol-choline oxidoreductase family.  

PubMed

Formate oxidase (FOD), which catalyzes the oxidation of formate to yield carbon dioxide and hydrogen peroxide, belongs to the glucose-methanol-choline oxidoreductase (GMCO) family. FOD from Aspergillus oryzae RIB40, which has a modified FAD as a cofactor, was crystallized at 293 K by the hanging-drop vapour-diffusion method. The crystal was orthorhombic and belonged to space group C222(1). Diffraction data were collected from a single crystal to 2.4 A resolution. PMID:20823527

Maeda, Yoshifumi; Doubayashi, Daiju; Ootake, Takumi; Oki, Masaya; Mikami, Bunzo; Uchida, Hiroyuki

2010-08-26

114

Immobilization of polyphenol oxidase on chitosan–SiO 2 gel for removal of aqueous phenol  

Microsoft Academic Search

A partially purified potato polyphenol oxidase (PPO) was immobilized in a cross-linked chitosan–SiO2 gel and used to treat phenol solutions. Under optimized conditions (formaldehyde 20 mg\\/ml, PPO 4 mg\\/ml and pH 7.0), the activity\\u000a of immobilized PPO was 1370 U\\/g and its K\\u000a m value for catechol was 12 mm at 25C. The highest activity of immobilized enzyme was at pH 7.4. Immobilization stabilized

Jian Shao; Huimin Ge; Yumin Yang

2007-01-01

115

Preparation and Structural Characterization of Nickel(II) Catecholates.  

PubMed

The early literature of catecholate complexes of Ni(II) is explained with regard to both high-spin octahedral and low-spin square-planar complexes. The former contain coordinated solvent, while the latter do not. The syntheses of the paramagnetic (S = 1; &mgr;(eff) = 2.93 &mgr;(B) at 300 K) octahedral Ni(II) complex Na(2)[trans-(H(2)O)(2)(cat)(2)Ni(II)].12H(2)O (1a) and the diamagnetic square-planar Ni(II) complex Na(2)[(cat)(2)Ni(II)].2DMF (2) are described. The physical and chemical properties of these Ni catecholates and their X-ray crystal structures are presented. In aqueous solution at low temperature the centrosymmetric octahedral complex is formed, which has average Ni-O distances of 2.044(3) Ĺ (catecholate) and 2.162(3) Ĺ (water). At higher temperature or under more weakly solvating conditions the square-planar complex is formed; the complex 2 is centrosymmetric with an average Ni-O(catecholate) distance of 1.863(3) Ĺ. The crystals of 1a conform to space group C2/c, with unit cell dimensions a = 26.0287(8) Ĺ, b= 9.0016(3) Ĺ, c = 10.6992(3) Ĺ, beta = 101.809(1) degrees, V = 2453.8(1) Ĺ(3), and Z = 4. Those of 2 conform to space group P2(1)/m, with unit cell dimensions a = 6.0906(5) Ĺ, b = 13.208(1) Ĺ, c = 12.826(1) Ĺ, beta = 95.711(1) degrees, V = 1026.7(1) Ĺ(3), and Z = 2. PMID:11670810

Brückner, Christian; Caulder, Dana L.; Raymond, Kenneth N.

1998-12-28

116

Quartz-capillary gas chromatography of chlorinated phenols and catechols  

Microsoft Academic Search

The gas chromatography of all chlorinated phenols and catechols on a non-polar SE-30 quartz-capillary column has been studied. The relative retention times of the individual components are given and the elution order is discussed. All of the chlorophenols and chlorocatechols can be separated under appropriate operating conditions but simultaneous determination of all the compounds studied resulted in overlapping peaks. Theortho-effect

I. O. O. Korhonen; J. Knuutinen

1983-01-01

117

Salmochelin, the long-overlooked catecholate siderophore of Salmonella  

Microsoft Academic Search

Salmochelin is a C-glucosylated enterobactin produced by Salmonella species, uropathogenic and avian pathogenic Escherichia coli strains, and certain Klebsiella strains. It was the first glucosylated siderophore described. The glucosylation has been interpreted as a bacterial evasion\\u000a mechanism against the mammalian catecholate siderophore-binding protein siderocalin (NGAL-lipocalin). The synthesis, excretion,\\u000a and uptake of salmochelin requires five genes, iroBCDEN, and also the enterobactin

Silke I. Müller; Marianne Valdebenito; Klaus Hantke

2009-01-01

118

Biosynthesis and Characterization of Laccase Catalyzed Poly(Catechol)  

Microsoft Academic Search

Enzymatic polymerization of catechol was conducted batch-wise using laccase enzyme produced by the culture Trametes versicolor (ATCC 200801). The polymerization reaction was carried out in 1:1 (v\\/v) aqueous-acetone solution, buffered at pH 5.0 with sodium acetate (50 mM) in a sealed, temperature-controlled reactor at 25°C. The molecular weight of the produced polymer was determined with GPC. FT-IR, DSC, and TGA

Nahit Akta?; Nurettin ?ahiner; Ömer Kanto?lu; Bekir Salih; Abdurrahman Tanyolaç

2003-01-01

119

Temperature dependent vapor pressures of chlorinated catechols, syringols, and syringaldehydes  

Microsoft Academic Search

The vapor pressures of nine chlorinated catechols, syringols, and syringaldehydes were determined as a function of temperature with a gas chromatographic retention time technique. The vapor pressures at 298.15 K were in the range of 0.02--1 Pa, and the enthalpies of vaporization, between 68 and 82 kJ\\/mol. The validity of the technique was established by a calibration involving four chlorinated

Ying Duan Lei; W. Y. Shiu; D. G. B. Boocock; F. Wania

1999-01-01

120

Heterogeneous cracking of catechol under partially oxidative conditions  

Microsoft Academic Search

Heterogeneous cracking of catechol over the temperature range of 350–650 °C and under partially oxidative conditions was studied using nano-particle iron oxide. We employed a flow tube reactor set-up for heterogeneous cracking, a molecular beam mass spectrometer for the real time sampling and measurement of cracking products, and factor analysis to deconvolute the complex chemistry. The effects on conversion and

Eun-Jae Shin; Mohammad R. Hajaligol; Firooz Rasouli

2004-01-01

121

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

SciTech Connect

Process of removal of compounds is described containing at least one of vanadium and nickel from spent catecholated polymer comprising: (a) acidifying a spent catecholated polystyrene-divinylbenzene polymer containing at least one of vanadium and nickel, which has been removed from a petroliferous liquid in the presence of an amine stabilizer by contact with the cathecholated polymer, with sufficient of an acidifying agent to hydrolyze the catechol moieties of the polymer and thereby to release the at least one of vanadium and nickel complexed therewith, the hydrolysis and release providing a regenerated catecholated polystyrene-divinylbenzene polymer; and (b) separating the regenerated catecholated polystyrene-divinylbenzene polymer from at least one of vanadium and nickel. Process of removal of compounds is described containing arsenic and at least one of vanadium and nickel from mixed spent catecholated polymer.

Fish, R.H.

1987-04-21

122

Immobilization of Amphiphilic Polycations by Catechol Functionality for Antimicrobial Coatings  

PubMed Central

A new strategy to prepare antimicrobial surfaces by a simple dip-coating procedure is reported. Amphiphilic polycations with different mole ratios of monomers containing dodecyl quaternary ammonium, methoxyethyl, and catechol groups were synthesized by free-radical polymerization. The polymer coatings were prepared by immersing glass slides into a polymer solution and subsequent drying and heating. The quaternary ammonium side chains endow the coatings with potent antibacterial activity, while the methoxyetyhyl side chains enable tuning the hydrophobic/hydrophilic balance and the catachol groups promote immobilization of the polymers into films. The polymer coated surfaces displayed bactericidal activity against Escherichia coli and Staphylococcus aureus in a dynamic contact assay and prevented accumulation of viable E. coli, S. aureus, and Acinetobacter baumannii for up to 96 hours. Atomic force microscopy (AFM) images of coating surfaces indicated that the surfaces exhibit virtually the same smoothness for all polymers except the most hydrophobic. The hydrophobic polymer without methoxyethyl side chains showed clear structuring into polymer domains, causing high surface roughness. Sum-frequency generation (SFG) vibrational spectroscopy characterization of the surface structures demonstrated that the dodecyl chains are predominantly localized at the surface-air interface of the coatings. SFG also showed that the phenyl groups of the catechols are oriented on the substrate surface. These results support our hypothesis that the adhesive or cross-linking functionality of catechol groups discourages leaching of polymers, allowing tuning of the amphiphilic balance by incorporating hydrophilic components into the polymer chains to gain potent biocidal activity.

Han, Hua; Wu, Jianfeng; Avery, Christopher W.; Mizutani, Masato; Jiang, Xiaoming; Kamigaito, Masami; Chen, Zhan; Xi, Chuanwu; Kuroda, Kenichi

2011-01-01

123

Immobilization of amphiphilic polycations by catechol functionality for antimicrobial coatings.  

PubMed

A new strategy for preparing antimicrobial surfaces by a simple dip-coating procedure is reported. Amphiphilic polycations with different mole ratios of monomers containing dodecyl quaternary ammonium, methoxyethyl, and catechol groups were synthesized by free-radical polymerization. The polymer coatings were prepared by immersing glass slides into a polymer solution and subsequent drying and heating. The quaternary ammonium side chains endow the coatings with potent antibacterial activity, the methoxyethyl side chains enable tuning the hydrophobic/hydrophilic balance, and the catachol groups promote immobilization of the polymers into films. The polymer-coated surfaces displayed bactericidal activity against Escherichia coli and Staphylococcus aureus in a dynamic contact assay and prevented the accumulation of viable E. coli, S. aureus, and Acinetobacter baumannii for up to 96 h. Atomic force microscopy (AFM) images of coating surfaces indicated that the surfaces exhibit virtually the same smoothness for all polymers except the most hydrophobic. The hydrophobic polymer without methoxyethyl side chains showed clear structuring into polymer domains, causing high surface roughness. Sum-frequency generation (SFG) vibrational spectroscopy characterization of the surface structures demonstrated that the dodecyl chains are predominantly localized at the surface-air interface of the coatings. SFG also showed that the phenyl groups of the catechols are oriented on the substrate surface. These results support our hypothesis that the adhesive or cross-linking functionality of catechol groups discourages polymer leaching, allowing the tuning of the amphiphilic balance by incorporating hydrophilic components into the polymer chains to gain potent biocidal activity. PMID:21391641

Han, Hua; Wu, Jianfeng; Avery, Christopher W; Mizutani, Masato; Jiang, Xiaoming; Kamigaito, Masami; Chen, Zhan; Xi, Chuanwu; Kuroda, Kenichi

2011-03-10

124

Fluorescence quenching method for the determination of catechol with gold nanoparticles and tyrosinase hybrid system  

Microsoft Academic Search

The determination method of catechol by fluorescence quenching was developed. The assay was based on the combination of the unique property of gold nanoparticles with tyrosinase enzymatic reaction. In the presence of tyrosinase, the fluorescence of gold nanoparticles was quenched by catechol which can be employed to detect catechol. Under the optimal conditions, a linear range 5.0×10?7–1.0×10?3molL?1 and a detection

Wen Juan Dong; Jin Ping Song; Chuan Dong; Martin M. F. Choi

2010-01-01

125

A process optimization for bio-catalytic production of substituted catechols (3-nitrocatechol and 3-methylcatechol  

Microsoft Academic Search

BACKGROUND: Substituted catechols are important precursors for large-scale synthesis of pharmaceuticals and other industrial products. Most of the reported chemical synthesis methods are expensive and insufficient at industrial level. However, biological processes for production of substituted catechols could be highly selective and suitable for industrial purposes. RESULTS: We have optimized a process for bio-catalytic production of 3-substituted catechols viz. 3-nitrocatechol

Dhan Prakash; Janmejay Pandey; Bhupendra N Tiwary; Rakesh K Jain

2010-01-01

126

Synthesis and characterization of poly(catechol) catalyzed by porphyrin and enzyme  

Microsoft Academic Search

Catalytic polymerization of catechol was performed employing the cationic porphyrin and horseradish peroxidase (HRP) as catalysts.\\u000a The obtained results demonstrate that the cationic metalloporphyrin is a more-efficient catalyst than the HRP in the catechol\\u000a polymerization. The oxidative polymerization was carried out in the presence of polystyrene sulfonate (PSS) as a template.\\u000a According to TGA data, poly(catechol) that is synthesized by

Mohammad Reza Nabid; Zahra Zamiraei; Roya Sedghi; Shidokht Nazari

2010-01-01

127

Selective O-methylation of catechol using dimethyl carbonate over calcined Mg?Al hydrotalcites  

Microsoft Academic Search

Methylation of catechol with dimethyl carbonate as an alkylating agent has been carried out over calcined Mg?Al hydrotalcites in the temperature range 523–623K. Guaiacol and veratrole were obtained as the major products, along with small amounts of catechol carbonate and C-alkylated products. At 573K, the total O-selectivity was 96.1% with a guaiacol selectivity of 84%. At higher DMC\\/catechol molar ratios

T. M. Jyothi; T. Raja; M. B. Talawar; B. S. Rao

2001-01-01

128

Separation of Close-Boiling Mixtures of 4Methoxyphenol\\/Catechol with tert-Butanol  

Microsoft Academic Search

Solid-liquid equilibrium (SLE) behavior was observed for close-boiling mixtures of 4-methoxyphenol and catechol with tert-butanol. The experimental liquidus lines of binary systems showed that intermolecular complex compounds were formed in both tert-butanol\\/4-methoxyphenol and tert-butanol\\/catechol, implying that tert-butanol is a potential medium to serve as an adductive agent for separation of 4-methoxyphenol and catechol. A ternary SLE phase diagram for the

Ming-Jer Lee; Yao-Kun Chang; Ho-Mu Lin

1998-01-01

129

Mechanisms of product formation from the pyrolytic thermal degradation of catechol  

Microsoft Academic Search

Catechol has been identified as one of the most abundant organic products in tobacco smoke and a major molecular precursor for semiquinone type radicals in the combustion of biomass material. The high-temperature gas-phase pyrolysis of catechol under hydrogen-rich and hydrogen-lean conditions was studied using a fused-silica tubular flow reactor coupled to an in-line GC\\/MS analytical system. Thermal degradation of catechol

Slawomir Lomnicki; Hieu Truong; Barry Dellinger

2008-01-01

130

Catechol sensor using poly(aniline-co- o-aminophenol) as an electron transfer mediator  

Microsoft Academic Search

In this work, poly(aniline-co-o-aminophenol) (copolymer) was used as an electron transfer mediator in the electrochemical oxidation of catechol due to its reversible redox over a wide range of pH. The experimental results indicate that the anodic peak potential of catechol at the copolymer electrode is lower than that at the platinum electrode in a solution consisting of catechol and sodium

Shaolin Mu

2006-01-01

131

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

132

Identification of Genes Required for Nonhost Resistance to Xanthomonas oryzae pv. oryzae Reveals Novel Signaling Components  

Microsoft Academic Search

BackgroundNonhost resistance is a generalized, durable, broad-spectrum resistance exhibited by plant species to a wide variety of microbial pathogens. Although nonhost resistance is an attractive breeding strategy, the molecular basis of this form of resistance remains unclear for many plant-microbe pathosystems, including interactions with the bacterial pathogen of rice, Xanthomonas oryzae pv. oryzae (Xoo).Methods and FindingsVirus-induced gene silencing (VIGS) and

Wen Li; You-Ping Xu; Zhi-Xin Zhang; Wen-Yuan Cao; Fei Li; Xueping Zhou; Gong-You Chen; Xin-Zhong Cai

2012-01-01

133

Prokaryotic orthologues of mitochondrial alternative oxidase and plastid terminal oxidase  

Microsoft Academic Search

The mitochondrial alternative oxidase (AOX) and the plastid terminal oxidase (PTOX) are two similar members of the membrane-bound diiron carboxylate group of proteins. AOX is a ubiquinol oxidase present in all higher plants, as well as some algae, fungi, and protists. It may serve to dampen reactive oxygen species generation by the respiratory electron transport chain. PTOX is a plastoquinol

Allison E. McDonald; Sasan Amirsadeghi; Greg C. Vanlerberghe

2003-01-01

134

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

135

Analysis of catRABC operon for catechol degradation from phenol-degrading Rhodococcus erythropolis  

Microsoft Academic Search

The gene cluster catRABC, involved in catechol degradation, was isolated from Rhodococcus erythropolis CCM2595. The genes catA, catB, catC, and the divergently transcribed catR code for catechol 1,2-dioxygenase, cis,cis-muconate cycloisomerase, muconolactone isomerase, and an IclR-type transcriptional regulator, respectively. Measurements\\u000a of catechol 1,2-dioxygenase activity showed that the expression of catA is induced by phenol but not by catechol or cis,cis-muconate. The

M. Veselý; M. Knoppová; J. Nešvera; M. Pátek

2007-01-01

136

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...

137

CHARACTERISTICS OF POLYPHENOL OXIDASES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Polyphenol oxidase (PPO, EC 1.14.18.1 or EC 1.10.3.1) catalyzes the oxidation of o-diphenols to o-quinones. Highly reactive o-quinones couple with phenolics and specific amino acids on proteins to form the characteristic browning products in many wounded fruits, vegetables, and leaf tissues of plant...

138

Adsorptive removal of aniline by granular activated carbon from aqueous solutions with catechol and resorcinol  

Microsoft Academic Search

In the present paper, the removal of aniline by adsorption process onto granular activated carbon (GAC) is reported from aqueous solutions containing catechol and resorcinol separately. The Taguchi experimental design was applied to study the effect of such parameters as the initial component concentrations (C0, i) of two solutes (aniline and catechol or aniline and resorcinol) in the solution, temperature

S. Suresh; V. C. Srivastava; I. M. Mishra

2012-01-01

139

Succinimide complexes of borated alkyl catechols and lubricating oil compositions containing same  

SciTech Connect

A composition is described comprising a complex prepared by reacting a borated alkyl catechol and an oil soluble alkyl or alkenyl succinimide wherein the weight percent ratio of the alkyl or alkenyl succinimide to the borated alkyl catechol ranges from 3:1 to 16:1.

Liston, T.V.

1986-12-16

140

Catechol-O-methyltransferase in rat sensory ganglia and spinal cord.  

PubMed

The localization of catechol-O-methyltransferase immunoreactivity in rat dorsal root ganglia and in the spinal cord and its co-existence with substance P, calcitonin gene-related peptide and fluoride-resistant acid phosphatase in dorsal root ganglion cells was examined with immunohistochemical and histochemical double-staining methods. Analysis of dorsal of dorsal root ganglia at both cervical and lumbar levels revealed catechol-O-methyltransferase immunoreactivity in numerous dorsal root ganglion cells. Double-staining studies showed that catechol-O-methyltransferase and substance P immunoreactivities were located in different cells with a few exceptions, whereas both catechol-O-methyltransferase and calcitonin gene-related peptide immunoreactivities were detected in about 10% of all labeled cells positive for one of the two markers at both levels studied. The great majority of fluoride-resistant alkaline phosphatase-positive cells were also immunoreactive for catechol-O-methyltransferase. Again, no difference was found between cervical and lumbar levels. Catechol-O-methyltransferase immunoreactivity was also found in the neuropil of the dorsal horn of the spinal cord. The staining was most intense in the superficial laminae (I-III) and overlapped partly with substance P and calcitonin gene-related peptide immunoreactivity. Western blotting analysis revealed that soluble catechol-O-methyltransferase was the clearly dominating form of the enzyme in dorsal root ganglia. The distribution pattern of catechol-O-methyltransferase in dorsal horn and sensory neurons suggests that the enzyme may modulate sensory neurotransmission. PMID:8783248

Karhunen, T; Ulmanen, I; Panula, P

1996-07-01

141

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

142

Nitric oxide generated by the rice blast fungus Magnaporthe oryzae drives plant infection.  

PubMed

Plant-derived nitric oxide (NO) triggers defence, priming the onset of the hypersensitive response and restricting pathogen ingress during incompatibility. However, little is known about the role of pathogen-produced NO during pre-infection development and infection. We sought evidence for NO production by the rice blast fungus during early infection. NO production was measured using fluorescence of DAR-4M and the role of NO assessed using NO scavengers. The synthesis of NO was investigated by targeted knockout of genes potentially involved in NO synthesis, including nitric oxide synthase-like genes (NOL2 and NOL3) and nitrate (NIA1) and nitrite reductase (NII1), generating single and double ?nia1?nii1, ?nia1?nol3, and ?nol2?nol3 mutants. We demonstrate that Magnaporthe oryzae generates NO during germination and in early development. Removal of NO delays germling development and reduces disease lesion numbers. NO is not generated by the candidate proteins tested, nor by other arginine-dependent NO systems, by polyamine oxidase activity or non-enzymatically by low pH. Furthermore, we show that, while NIA1 and NII1 are essential for nitrate assimilation, NIA1, NII1, NOL2 and NOL3 are all dispensable for pathogenicity. Development of M. oryzae and initiation of infection are critically dependent on fungal NO synthesis, but its mode of generation remains obscure. PMID:23072575

Samalova, Marketa; Johnson, Jasper; Illes, Mary; Kelly, Steven; Fricker, Mark; Gurr, Sarah

2012-10-16

143

Caffeoyltartronic acid from catnip ( Nepeta cataria ): A precursor for catechol in lubber grasshopper ( Romalea guttata ) defensive secretions  

Microsoft Academic Search

Adults of the lubber grasshopper (Romalea guttata) secrete increased amounts of catechol from their defensive glands when fed diets containing only catnip leaves (Nepeta cataria). Model compound bioassays showed that these insects were able to sequester and biomagnify simple phenols, such as catechol and hydroquinone, in their defense gland secretions. Excessive catechol secretions from caffeic acid-fortified diets indicated metabolic pathways

Maurice E. Snook; Murray S. Blum; Douglas W. Whitman; Richard F. Arrendale; Catherine E. Costello; John S. Harwood

1993-01-01

144

Pathways for formation of catechol and 1,2,4-benzenetriol in rabbits  

SciTech Connect

Benzene, an established human leukemogen, was once widely used as an industrial solvent and is currently an important material for organic synthesis. Its metabolism in man and animals has also been studied extensively, and phenolic compounds were identified as major metabolites in urine after benzene exposure. One point yet to be elucidated is the pathway for formation of catechol (or 1,2-benzenediol). Early studies suggested that catechol will be formed via phenol whereas a later study failed to identify catechol in the urine of men and rabbits after oral administration methods of {sup 14}C-phenol. Sensitive HPLC methods have been recently developed in our laboratory to measure urinary phenolic metabolites and t,t-muconic acid. The methods were applied to show that phenol is not a precursor of catechol in rabbits. Evidence is also presented that 1,2,4-benzenetriol is formed only from quinol (1,4-benzenediol) and not from catechol.

Inoue, Osamu; Seiji, Kazunori (Tohoku Rosai Hospital, Sendai (Japan) Tohoku Univ. School of Medicine, Sendai (Japan)); Ikeda, Masayuki (Tohoku Univ. School of Medicine, Sendai (Japan))

1989-08-01

145

Trehalase in Conidia of Aspergillus oryzae  

PubMed Central

Horikoshi, Koki (The Institute of Physical and Chemical Research, Bunkyo-ku, Tokyo, Japan), and Yonosuke Ikeda. Trehalase in conidia of Aspergillus oryzae. J. Bacteriol. 91:1883–1887. 1966.—Trehalases (soluble trehalase and coat-bound trehalase) were found in the conidia of Aspergillus oryzae, and the total activity of the trehalases increased during the germination process. The soluble trehalase was purified by diethylaminoethyl-cellulose column chromatography; its optimal pH, Michaelis constant, and heat stability were studied. In vitro, the trehalases were competitively inhibited by d-mannitol, which was also contained in the conidia. Since the trehalose content in the conidia decreased at an early stage of germination, it was assumed that trehalase might begin to hydrolyze trehalose after the inhibitory effect of d-mannitol decreased.

Horikoshi, Koki; Ikeda, Yonosuke

1966-01-01

146

Lysyl Oxidase and Lysyl Oxidase-Like Enzymes  

Microsoft Academic Search

\\u000a Lysyl oxidase (LOX) and its four congeners, lysyl oxidase-like 1 (LOXL1), -2, -3, and -4, have received much investigative\\u000a attention in recent years. LOX itself, is the prototypic form of these amine oxidase enzymes. LOX has long been considered\\u000a to function exclusively as the enzyme that oxidizes peptidyl lysine in its collagen and elastin substrates, thereby initiating\\u000a formation of the

Herbert M. Kagan; Faina Ryvkin

147

Methyl conjugation in uraemia: catechol-O-methyltransferase.  

PubMed

1 Erythrocyte (RBC) catechol-9-methyltransferase (COMT) activity is significantly higher in erythrocytes from uraemic patients on maintenance haemodialysis, 18.7 +/- 1.4 units/ml RBC (mean +/- s.e. mean, n = 22) than in the blood of randomly selected subjects, 12.0 +/- 0.2 units/ml (mean +/- s.e. mean, n = 557, P < 0.001). 2 Uraemic plasma contains larger quantities of endogenous methyl acceptors than does normal plasma, and it reversibly inhibits RBC lysate COMT activity to a greater degree than does normal plasma. 3 There are large individual variations in the degree of inhibition of RBC COMT activity plasma from patients with renal failure. Inhibition varied from 10-43% when 40 microliters plasma from each of 19 randomly selected uraemic patients was tested, and there as a direct correlation between the inhibition of COMT by plasma from an individual uraemic patient and its content of endogenous methyl acceptors (r = 0.64, n = 19, P < 0.01). 4 Kinetic studies with pooled uraemic plasma demonstrate that inhibition of COMT by uraemic plasma is uncompetitive with respect to both the catechol substrate and the methyl donor for the reaction, S-adenosyl-L-methionine. 5 Plasma from uraemic patients does not inhibit partially purified rat liver COMT, an observation which suggests that the inhibition is not due to a direct effect on COMT but requires the presence of other constituents of the RBC lysate, perhaps other methyltransferase enzymes. PMID:7437264

Pazmińo, P A; Weinshilboum, R M

1980-11-01

148

Methyl conjugation in uraemia: catechol-O-methyltransferase.  

PubMed Central

1 Erythrocyte (RBC) catechol-9-methyltransferase (COMT) activity is significantly higher in erythrocytes from uraemic patients on maintenance haemodialysis, 18.7 +/- 1.4 units/ml RBC (mean +/- s.e. mean, n = 22) than in the blood of randomly selected subjects, 12.0 +/- 0.2 units/ml (mean +/- s.e. mean, n = 557, P < 0.001). 2 Uraemic plasma contains larger quantities of endogenous methyl acceptors than does normal plasma, and it reversibly inhibits RBC lysate COMT activity to a greater degree than does normal plasma. 3 There are large individual variations in the degree of inhibition of RBC COMT activity plasma from patients with renal failure. Inhibition varied from 10-43% when 40 microliters plasma from each of 19 randomly selected uraemic patients was tested, and there as a direct correlation between the inhibition of COMT by plasma from an individual uraemic patient and its content of endogenous methyl acceptors (r = 0.64, n = 19, P < 0.01). 4 Kinetic studies with pooled uraemic plasma demonstrate that inhibition of COMT by uraemic plasma is uncompetitive with respect to both the catechol substrate and the methyl donor for the reaction, S-adenosyl-L-methionine. 5 Plasma from uraemic patients does not inhibit partially purified rat liver COMT, an observation which suggests that the inhibition is not due to a direct effect on COMT but requires the presence of other constituents of the RBC lysate, perhaps other methyltransferase enzymes.

Pazmino, P A; Weinshilboum, R M

1980-01-01

149

Somaclonal genetics of rice, Oryza sativa L  

Microsoft Academic Search

The inheritance and variations of some traits of more than 2,000 somatic cell derived plants of rice (Oryza sativa L.) were investigated in the second and third generations (T2 and T3) of regenerated plants (somaclones). The percentages of multiploids occurring in somaclones ranged from 0–13.3 in nine varieties (or hybrids) of ‘Hsien’ (indica) group, but no multiploid was found in

Sun Zong-xiu; Zhao Cheng-zhang; Zheng Kang-le; Qi Xiu-fang; Fu Ya-ping

1983-01-01

150

Phylogeny and Biogeography of the Genus Oryza  

Microsoft Academic Search

Plants with characteristics of species belonging to the tribe Oryzeae were present in India more than 60 million years ago\\u000a (Ma), early in the history of grasses (Prasad et al. 2005). This tribe is now represented by 11 genera that are found in tropical\\u000a and temperate regions of the world. Among genera in the tribe Oryzeae, the genus Oryza, with

Duncan A. Vaughan; Song Ge; Akito Kaga; Norihiko Tomooka

151

Multicopper oxidases and oxygenases  

Microsoft Academic Search

Copper is an essential trace element in living systems, present in the parts per million concentration range. It is a key cofactor in a diverse array of biological oxidation-reduction reactions. These involve either outer-sphere electron transfer, as in the blue copper proteins and the Cu{sub A} site of cytochrome oxidase and nitrous oxide redutase, or inner-sphere electron transfer in the

Edward I. Solomon; Uma M. Sundaram; Timothy E. Machonkin

1996-01-01

152

Detoxication of structurally diverse polycyclic aromatic hydrocarbon (PAH) o-quinones by human recombinant catechol-O-methyltransferase (COMT) via O-methylation of PAH catechols.  

PubMed

Polycyclic aromatic hydrocarbons (PAH) are environmental and tobacco carcinogens. Metabolic activation of intermediate PAH trans-dihydrodiols by aldo-keto reductases (AKRs) leads to the formation of electrophilic and redox-active o-quinones. We investigated whether O-methylation by human recombinant soluble catechol-O-methyltransferase (S-COMT) is a feasible detoxication step for a panel of structurally diverse PAH-catechols produced during the redox-cycling process. Classes of PAH non-K-region o-quinones (bay region, methylated bay region, and fjord region o-quinones) produced by AKRs were employed in the studies. PAH o-quinones were reduced to the corresponding catechols by dithiothreitol under anaerobic conditions and then further O-methylated by human S-COMT in the presence of S-[łH]adenosyl-l-methionine as a methyl group donor. The formation of the O-methylated catechols was detected by HPLC-UV coupled with in-line radiometric detection, and unlabeled products were also characterized by LC-MS/MS. Human S-COMT was able to catalyze O-methylation of all of the PAH-catechols and generated two isomeric metabolites in different proportions. LC-MS/MS showed that each isomer was a mono-O-methylated metabolite. ąH NMR was used to assign the predominant positional isomer of benzo[a]pyrene-7,8-catechol as the O-8-monomethylated catechol. The catalytic efficiency (k(cat)/K(m)) varied among different classes of PAH-catechols by 500-fold. The ability of S-COMT to produce two isomeric products from PAH-catechols was rationalized using the crystal structure of the enzyme. We provide evidence that O-8-monomethylated benzo[a]pyrene-7,8-catechol is formed in three different human lung cell lines. It is concluded that human S-COMT may play a critical role in the detoxication of PAH o-quinones generated by AKRs. PMID:21622560

Zhang, Li; Jin, Yi; Chen, Mo; Huang, Meng; Harvey, Ronald G; Blair, Ian A; Penning, Trevor M

2011-05-27

153

NADH oxidase of plasma membranes  

Microsoft Academic Search

NADH oxidase is a cyanide-resistant and hormone-responsive oxidase intrinsic to the plasma membrane of both plant and animal cells. The activity has many unique characteristics that distinguish it from other oxidases and oxidoreductases of both organelles and internal membranes and from other oxidoreductases of the plasma membrane. Among these are resistance to inhibition by cyanide, catalase, superoxide dismutase, and phenylchloromer-curibenzoate.

D. James Morré; Andrew O. Brightman

1991-01-01

154

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

155

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

156

Trichoderma harzianum : a biocontrol agent against Bipolaris oryzae  

Microsoft Academic Search

Rice brown spot, caused by Bipolaris oryzae, can be a serious disease causing a considerable yield loss. Trichoderma harzianum is an effective biocontrol agent for a number of plant fungal diseases. Thus, this research was carried out to investigate\\u000a the mechanisms of action by which T. harzianum antagonizes Bipolaris oryzae in vitro, and the efficacy of spray application of a

Gamal M. Abdel-Fattah; Yasser M. Shabana; Adel E. Ismail; Younes Mohamed Rashad

2007-01-01

157

African rice (Oryza glaberrima): History and future potential  

PubMed Central

The African species of rice (Oryza glaberrima) was cultivated long before Europeans arrived in the continent. At present, O. glaberrima is being replaced by the introduced Asian species of rice, Oryza sativa. Some West African farmers, including the Jola of southern Senegal, still grow African rice for use in ritual contexts. The two species of rice have recently been crossed, producing a promising hybrid.

Linares, Olga F.

2002-01-01

158

Biosynthesis and cytoplasmic accumulation of a chlorinated catechol pigment during 3-chlorobenzoate aerobic co-metabolism in Pseudomonas fluorescens.  

PubMed

A strain of Pseudomonas fluorescens was capable of co-metabolizing 3-chlorobenzoic acid with the production of a chlorinated catechol black pigment. A peroxidase and another enzymatic activity referred to as a polyphenol oxidase were found to be involved in the oxidation of 4-chlorocatechol to 4-chloro-1,2-benzoquinone, i.e. in the production of highly reactive substrates for pigment formation. Therefore, P. fluorescens cells were seen to take an active part not only in 3-chlorobenzoate mineralization but also in overall pigment production. pH was found to be a key parameter in the regulation of the activity of P. fluorescens oxidoreductive enzymes. Ultrastructural investigations showed that electron dense granules of pigment were distributed throughout the cytoplasm of Pseudomonas fluorescens cells grown in presence of 3-chlorobenzoate, as confirmed also by Thiéry cytochemical investigations. In these cells, an extensive contraction of the cytoplasm as well as a significant damage to the cell wall after two days of incubation, suggested that pigment production caused a premature death of the cells accompanied by the leakage of the cell content. Pigment production seemed to occur mostly in the cytoplasmic context where the electron dense material accumulates until it is released in the medium after the cell lysis. PMID:8257280

Fava, F; Di Gioia, D; Romagnoli, C; Marchetti, L; Mares, D

1993-01-01

159

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

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

1992-01-01

160

Role of the FeoB protein and siderophore in promoting virulence of Xanthomonas oryzae pv. oryzae on rice.  

PubMed

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

2010-04-09

161

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

2012-03-15

162

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

163

Purification methods of mammalian catechol-O-methyltransferases.  

PubMed

The protein purification strategies used for obtaining homogeneous rat and human soluble catechol-O-methyltransferase (S-COMT) polypeptides are reviewed. Expression and purification of recombinant rat and human S-COMT in Escherichia coli and for human S-COMT in baculevirus-infected insect cells made it possible to elucidate the S-COMT polypeptides in more detail. The application of these purification methods has allowed the crystallization of the rat S-COMT protein and the analysis of the kinetic properties of the enzyme in great detail. The availability of the pure S-COMT protein together with the structural data has also greatly enhanced the development of more potent COMT inhibitors. PMID:8906471

Tilgmann, C; Ulmanen, I

1996-09-20

164

Distribution of catechol-O-methyltransferase enzyme in rat tissues.  

PubMed

In the present study we show the distribution of catechol-O-methyltransferase (COMT) in various rat tissues with a highly specific antiserum prepared against recombinant rat COMT. Immunoprecipitation and immunocytochemical controls confirmed the COMT-specificity of the antibodies. The antiserum detected both the 24 KD soluble and the 28 KD membrane-bound forms of the enzyme. By immunohistochemical staining the COMT enzyme was found in most rat tissues. Staining was most intense in the liver and in the kidney, in agreement with previous studies and our immunoblotting results. In the gastrointestinal tract, epithelial cells of the stomach, duodenum, and ileum were immunoreactive for COMT. In pancreas, COMT immunoreactivity was found in insulin-producing beta-cells and somatostatin-producing D-cells but not in glucagon-producing alpha-cells of the islets of Langerhans. In pituitary, COMT immunoreactivity was found in cleft cells, in pituicytes of the posterior lobe, and in the anterior lobe, partly in the same cells containing luteinizing hormone (LH). In other endocrine organs, COMT immunoreactivity was found in epithelial cells of the thyroid gland and in zona glomerulosa of the adrenal cortex. In the brain, brightest immunofluorescence was seen in ependymal cells of the cerebral ventricles and choroid plexus. Weak to moderate immunofluorescence was found in the neuropil of several brain areas, including striatum and cortex. Scattered small neurons in spinal sensory ganglia were also COMT immunoreactive. Previous immunocytochemical studies, enzyme activity determinations, and distribution of the COMT mRNA are in general agreement with the results presented here. The wide distribution of COMT in different tissues suggests an important role for this protein in inactivation of catechol compounds. PMID:8027527

Karhunen, T; Tilgmann, C; Ulmanen, I; Julkunen, I; Panula, P

1994-08-01

165

?-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

2012-05-12

166

Thermally controlled wettability of a nanoporous membrane grafted with catechol-tethered poly(N-isopropylacrylamide).  

PubMed

A nanoporous membrane is coated with catechol-tethered poly(N-isopropylacrylamide). The thermosensitive variation of surface wettability determines the hindered diffusivity of dextran (40 kDa) through the nanopores. PMID:22783550

Kim, Jee Seon; Kim, Taek Gyung; Kong, Won Ho; Park, Tae Gwan; Nam, Yoon Sung

2012-07-11

167

Thermally stable drilling fluid additive comprised of a copolymer of catechol-based monomer  

SciTech Connect

A water soluble polymer is described having thermal stability and exhibiting utility as an aqueous drilling fluid additive comprising: (a) a major portion of a catechol based monomer; (b) a minor portion of a dicarboxylic acid monomer.

Patel, A.D.

1986-06-17

168

H-point curve isolation method for determination of catechol in complex unknown mixtures  

NASA Astrophysics Data System (ADS)

In this work, the combination of H-point curve isolation method (HPCIM) and H-point standard additions method (HPSAM) was used for determination of catechol in the presence of phenolic interferents. Spectrophotometric multivariate calibration data constructed by successive standard additions of an analyte in an unknown matrix was used by the method. A cumulative spectrum for interferents in sample was extracted by HPCIM and then HPSAM is used for determination of the catechol concentration by obtained cumulative interferents spectrum. The method was tested with simulated data set. The spectrum obtained from applying HPCIM to the simulated data well agrees with the cumulative spectra of the interferents. The method was applied to the determination of catechol in the presence of highly overlapping interferents in synthetic ternary mixtures using spectrophotometric data. Moreover, the proposed method was successfully used for determination of catechol in real complicated matrices of tea and urine samples. Percent recoveries were between 95.4 and 113.6.

Hasani, Masoumeh; Mohammadi, Masoumeh; Shariati-Rad, Masoud; Abdollahi, Hamid

2012-10-01

169

Biotransformation of benzene and toluene to catechols by phenol hydroxylase from Arthrobacter sp. W1.  

PubMed

Phenol hydroxylase gene engineered microorganism (PHIND) was used to synthesize catechols from benzene and toluene by successive hydroxylation reaction. HPLC-MS and (1)H NMR analysis proved that the products of biotransformation were the corresponding catechols via the intermediate production of phenols. It was indicated that the main products of toluene oxidation were o-cresol and p-cresol. 3-Methylcatechol was the predominant product for m-cresol biotransformation. Formation rate of catechol (25 ?M/min/g cell dry weight) was 1.43-fold higher than that of methylcatechols. It was suggested that phenol hydroxylase could be successfully used to transform both benzene and toluene to catechols by successive hydroxylation. PMID:22854893

Ma, Fang; Shi, Sheng-Nan; Sun, Tie-Heng; Li, Ang; Zhou, Ji-Ti; Qu, Yuan-Yuan

2012-08-02

170

Direction-dependent intermolecular interactions: catechol on TiO2(110)-1×1  

Microsoft Academic Search

The adsorption of a submonolayer of catechol (C6H6O2) on the rutile TiO2(110)-1×1 surface has been investigated by Scanning Tunneling Microscopy (STM). The catechol molecules are preferentially adsorbed on the surface 5-fold coordinated Ti4+ sites, and occupy two neighboring lattice Ti sites. No preference for adsorption at surface step edges is observed at room temperature. A statistical analysis of intermolecular distances

Shao-Chun Li; Ulrike Diebold

2009-01-01

171

Removal of catechol from aqueous solutions by adsorption onto organophilic-bentonite  

Microsoft Academic Search

Organophilic-bentonite, produced by exchange of cetyltrimethylammonium cation for metal cations on the bentonite, was exploited as adsorbent for removal of catechol from aqueous solutions using batch technique. The dependence of removal on various physico-chemical parameters, such as contact time (1–250min), concentration (0.8–15.3mmolL?1), temperature (30, 40, 50±1°C) and pH (5–12) of the adsorptive solution were investigated. Obtained results show that catechol

K. Shakir; H. F. Ghoneimy; A. F. Elkafrawy; Sh. G. Beheir; M. Refaat

2008-01-01

172

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

Microsoft Academic Search

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

Fish

1987-01-01

173

Polycyclic aromatic hydrocarbons from the co-pyrolysis of catechol and propyne  

Microsoft Academic Search

In order to investigate C3 species as potential participants in aromatic-ring-growth reactions of polycyclic aromatic hydrocarbons (PAH) from solid fuels, we have performed pyrolysis experiments in an isothermal laminar-flow reactor (at temperatures, 700–1000°C; residence time, 0.3s) with the C3 hydrocarbon propyne, the model fuel catechol (representative of aromatic moieties in coal and biomass), and with propyne and catechol together (in

Nimesh B. Poddar; Shiju Thomas; Mary J. Wornat

2011-01-01

174

Properties of catechol 1,2-dioxygenase from Pseudomonas putida immobilized in calcium alginate hydrogels  

Microsoft Academic Search

Catechol 1,2-dioxygenase from Pseudomonas putida was isolated and immobilized in calcium alginate hydrogels. The gel matrix could effectively entrap the enzyme, with high retention of activity. Following immobilization, catechol 1,2-dioxygenase exhibited improved storage stability and activity in the presence of organic solvents, and performed better at higher incubation temperatures. In addition, the enzyme retained most of its catalytic efficiency after

E. Kalogeris; Y. Sanakis; D. Mamma; P. Christakopoulos; D. Kekos; H. Stamatis

2006-01-01

175

Abiotic transformation of catechol and 1-naphthol in aqueous solution—Influence of environmental factors  

Microsoft Academic Search

The abiotic transformation of catechol and 1-naphthol singly and in mixtures was tested in sterile Tris-HCl buffer with regard to several environmental factors including temperature (7°C, 20°C and 30°C), lighting conditions, pH (between 7.0 and 8.5) and dissolved oxygen (at partial pressures of 0.0, 220, 2200, 11000 and 22000Pa).Irrespective of lighting conditions, catechol autoxidation was confirmed in aerated medium with

Rémi Borraccino; Mourad Kharoune; Renaud Giot; Spiros N Agathos; Edmond-Jacques Nyns; Henry P Naveau; André Pauss

2001-01-01

176

Human catechol O-methyltransferase genetic variation: gene resequencing and functional characterization of variant allozymes  

Microsoft Academic Search

Catechol O-methyltransferase (COMT) plays an important role in the metabolism of catecholamines, catecholestrogens and catechol drugs. A common COMT G472A genetic polymorphism (Val108\\/158Met) that was identified previously is associated with decreased levels of enzyme activity and has been implicated as a possible risk factor for neuropsychiatric disease. We set out to ‘resequence’ the human COMT gene using DNA samples from

A J Shield; B A Thomae; B W Eckloff; E D Wieben; R M Weinshilboum

2004-01-01

177

Catechol is the major product of salicylate hydroxylation in 1-methyl-4-phenylpyridinium ion treated rats.  

PubMed

Salicylate hydroxylation using hydroxyl free radicals results into formation of 2,3-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid and catechol. Inspite of the fact that in vitro experiments have shown that catechol is a minor product, we have shown by these in vivo studies that it is a substantial product. Since catechol as well as 2,3-dihydroxybenzoic acid have not been found to be produced enzymatically from salicylates, they appear useful as in vivo indicators for monitoring hydroxyl free radicals. Administration of 1-methyl-4-phenylpyridinium ion (MPP+) to rat striatum using microdialysis results into the formation of hydroxyl radicals. Salicylate perfusion enables the estimation of the three derivatives cited above. They increased significantly after MPP+ administration in comparison to the baseline values, with catechol being the most significant. The maximum amounts were achieved 60 min after MPP+ administration, and the mean percentage increase at this time point were 83.1% for 2,3-DBA (n = 6, P = 0.005), 81.25% for 2,5-DBA (n = 6, P = 0.011) and 1228.8% for catechol (n = 4, p = 0.00008). MPP+ caused substantial decrease of dopamine metabolites. Dihydroxyphenylacetic acid decreased to 13% and homovanillic acid to 11.4%. We conclude that catechol is an important indicator of hydroxyl free radical formation in this animal model which is well suited to study the role of free radicals in Parkinsonism. PMID:9725471

Sam, E; Sarre, S; Michotte, Y; Verbeke, N

178

A Novel Mechanism for Adenylyl Cyclase Inhibition from the Crystal Structure of its Complex with Catechol Estrogen  

SciTech Connect

Catechol estrogens are steroid metabolites that elicit physiological responses through binding to a variety of cellular targets. We show here that catechol estrogens directly inhibit soluble adenylyl cyclases and the abundant trans-membrane adenylyl cyclases. Catechol estrogen inhibition is non-competitive with respect to the substrate ATP, and we solved the crystal structure of a catechol estrogen bound to a soluble adenylyl cyclase from Spirulina platensis in complex with a substrate analog. The catechol estrogen is bound to a newly identified, conserved hydrophobic patch near the active center but distinct from the ATP-binding cleft. Inhibitor binding leads to a chelating interaction between the catechol estrogen hydroxyl groups and the catalytic magnesium ion, distorting the active site and trapping the enzyme substrate complex in a non-productive conformation. This novel inhibition mechanism likely applies to other adenylyl cyclase inhibitors, and the identified ligand-binding site has important implications for the development of specific adenylyl cyclase inhibitors.

Steegborn,C.; Litvin, T.; Hess, K.; Capper, A.; Taussig, R.; Buck, J.; Levin, L.; Wu, H.

2005-01-01

179

NADPH Oxidase and Neurodegeneration  

PubMed Central

NADPH oxidase (Nox) is a unique, multi-protein, electron transport system that produces large amounts of superoxide via the reduction of molecular oxygen. Nox-derived reactive oxygen species (ROS) are known to be involved in a variety of physiological processes, including host defense and signal transduction. However, over the past decade, the involvement of (Nox)-dependent oxidative stress in the pathophysiology of several neurodegenerative diseases has been increasingly recognized. ROS produced by Nox proteins contribute to neurodegenerative diseases through distinct mechanisms, such as oxidation of DNA, proteins, lipids, amino acids and metals, in addition to activation of redox-sensitive signaling pathways. In this review, we discuss the recent literature on Nox involvement in neurodegeneration, focusing on Parkinson and Alzheimer diseases.

Hernandes, Marina S; Britto, Luiz R G

2012-01-01

180

Multicopper oxidases and oxygenases  

SciTech Connect

Copper is an essential trace element in living systems, present in the parts per million concentration range. It is a key cofactor in a diverse array of biological oxidation-reduction reactions. These involve either outer-sphere electron transfer, as in the blue copper proteins and the Cu{sub A} site of cytochrome oxidase and nitrous oxide redutase, or inner-sphere electron transfer in the binding, activation, and reduction of dioxygen, superoxide, nitrite, and nitrous oxide. Copper sites have historically been divided into three classes based on their spectroscopic features, which reflect the geometric and electronic structure of the active site: type 1 (T1) or blue copper, type 2 (T2) or normal copper, and type 3 (T3) or coupled binuclear copper centers. 428 refs.

Solomon, E.I.; Sundaram, U.M.; Machonkin, T.E. [Stanford Univ., CA (United States). Dept. of Chemistry

1996-11-01

181

EFECTIVIDAD BIOLÓGICA DEL AZOXYSTROBIN PARA EL CONTROL DE Pyricularia oryzae Cav. Y Cercospora oryzae Miyake. EN ARROZ DE TEMPORAL EN VERACRUZ, MÉXICO 1  

Microsoft Academic Search

Biologic Evaluation of the Azoxystrobin to control Pyricularia oryzae Cav. and Cercospora oryzae Miyake in crop of rice in Veracruz, Mexico. In the state of Veracruz, Mexico, around 22000 ha of rice are sown annually; the average of yield is about 3.5 t\\/ha and it is mainly due to drought problems, which favours the presence of the fungi Pyricularia oryzae

Enrique Becerra; Oscar Tosquy; NOTA TÉCNICA

2001-01-01

182

Functional identification of the gene locus ( ncg 12319 and characterization of catechol 1,2-dioxygenase in Corynebacterium glutamicum  

Microsoft Academic Search

Corynebacterium glutamicum assimilated phenol, benzoate, 4-hydroxybenzoate p-cresol and 3,4-dihydroxybenzoate. Ring cleavage was by catechol 1,2-dioxygenase when phenol or benzoate was used and by protocatechuate 3,4-dioxygenase when the others were used as substrate. The locus ncg12319 of its genome was cloned and expressed in Escherichia coli. Enzyme assays showed that ncg12319 encodes a catechol 1,2-dioxygenase. This catechol 1,2-dioxygenase was purified and accepted

Shuang-Jiang Liu

2004-01-01

183

Macrocycles 23. Odd–even effect in the cyclization of poly(ester imide)s derived from catechols  

Microsoft Academic Search

Various poly(ester imide)s, PEIs, were prepared from N-(4-carboxyphenyl) trimellitimide (4-CPTI) or from N-(3-carboxyphenyl) trimellitimide (3-CPTI). Various catechols or 5-methylresorcinol served as comonomers. MALDI-TOF mass spectrometry revealed that the PEIs derived from 4-CPTI and catechols contain significantly more even than odd cycles, whereas the PEIs derived from 3-CPTI and catechols contained almost equal amounts of odd and even-numbered cycles. The predominant

Abbas A Shaikh; Gert Schwarz; Hans R Kricheldorf

2003-01-01

184

Development of catechol 2,3-dioxygenase-specific primers for monitoring bioremediation by competitive quantitative PCR  

Microsoft Academic Search

Benzene, toluene, xylenes, phenol, naphthalene, and biphenyl are among a group of compounds that have at least one reported pathway for biodegradation involving catechol 2,3-dioxygenase enzymes. Thus, detection of the corresponding catechol 2,3-dioxygenase genes can serve as a basis for identifying and quantifying bacteria that have these catabolic abilities. Primes that can successfully amplify a 238-bp catechol 2,3-dioxygenase gene fragment

MATTHEW B. MESARCH; CINDY H. NAKATSU; LORING NIES

2000-01-01

185

Distinguishing rice ( Oryza sativa poaceae) from wild Oryza species through phytolith analysis, II Finalized method  

Microsoft Academic Search

Asian rice is an important grain, not only in its homeland but in many areas of the world. Preliminary studies suggested that\\u000a phytolith analysis, the identification of opaline silica bodies, provided a reliable way of identifying rice, especially in\\u000a situations where preservation of charred botanical remains was poor. Results of this follow-up study, which incorporates all\\u000a Asian wild Oryza species

Zhijun Zhao; Deborah M. Pearsall; Robert A. Benfer; Dolores R. Piperno

1998-01-01

186

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

PubMed

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 CuCl(2) in tetrahydrofuran. They have been characterized by EPR, UV spectroscopy and cyclic voltammetry. The absence of the half-field splitting signals in EPR suggests that the complex exists in solution as mononuclear species. The influence of substituents and side chain of the tripodal ligand on the catecholase activity of the complexes was studied. The reaction rate depends on two factors. First, the presence of an oxygen atom in the third position of the side chain should be avoided to keep the effectiveness of the reaction. Second, the electronic and steric effects of substituents on the pyrazole ring strongly affect the catalytic activity of the complex. Thus, best results were obtained with complexes containing unsubstituted pyrazole based-ligands. Kinetic investigations with the best catalyst based on the Michaelis-Menten model show that the catalytic activity of the mononuclear complex is close to that of some dicopper complexes described in literature. PMID:21946439

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

2011-08-02

187

Less symmetrical dicopper(II) complexes as catechol oxidase models--an adjacent thioether group increases catecholase activity.  

PubMed

Three new unsymmetrical compartmental dinucleating ligands, 4-bromo-2-(4-methylpiperazin-1-ylmethyl)-6-[{2-(1-piperidyl)ethyl}aminomethyl]phenol (HL1), 4-bromo-2-(4-methylpiperazin-1-ylmethyl)-6-[{2-(morpholin-4-yl)ethyl}aminomethyl]phenol (HL2), and 4-bromo-2-(4-methylpiperazin-1-ylmethyl)-6-[{2-(thiomorpholin-4-yl)ethyl}aminomethyl]phenol (HL3), have been synthesized in order to model the active site of type 3 copper proteins. The dicopper(II) complexes of these ligands give first hints about the influence of a thioether group close to the metal site. The bromophenol-based ligands have one piperazine arm and one other bidentate arm in positions 2 and 6 of the phenolic ring, respectively. With each ligand a dinuclear copper(II) complex was prepared and structurally characterized. The copper ions were found to have square pyramidal environments and a mixture of endogenous phenoxo and exogenous acetate bridging. The influence of a heteroatom in one arm of the ligand on catecholase activity and speciation in solution was studied by UV/Vis spectroscopy, ESI-MS experiments and, DFT calculations. PMID:15619727

Merkel, Michael; Möller, Niclas; Piacenza, Manuel; Grimme, Stefan; Rompel, Annette; Krebs, Bernt

2005-02-01

188

Mono- and dinuclear manganese(III) complexes showing efficient catechol oxidase activity: syntheses, characterization and spectroscopic studies.  

PubMed

Four side-off compartmental ligands L1-L4 [L1 = N,N'-ethylenebis(3-formyl-5-methyl-salicylaldimine), L2 = N,N'-1-methylethylenebis(3-formyl-5-methylsalicylaldimine), L3 = N,N'-1,1-dimethylethylenebis(3-formyl-5-methylsalicylaldimine) and L4= N,N'-cyclohexenebis(3-formyl-5-methylsalicylaldimine)] having two binding sites, N2O2 and O4, have been chosen to synthesize mononuclear and dinuclear manganese(III) complexes with the aim to study their catecholase activity using 3,5-di-tert-butylcatechol (3,5-DTBC) as substrate in the presence of molecular oxygen. In all cases only mononuclear manganese complexes (1-4) were obtained, with manganese coordination taking place at the N2O2 binding site only, irrespective of the amount of manganese salt used. All these complexes have been characterized by routine physico-chemical techniques. Complex MnL2Cl.4H2O (2) has further been structurally characterized by X-ray single crystal structure analysis. Four dinuclear manganese complexes, 5-8, were obtained after condensing the two pending formyl groups on each ligand (L1-L4) with aniline followed by reaction with MnCl2 to put the second Mn atom onto another N2O2 site. The catalytic activity of all complexes 1-8 has been investigated following the oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tert-butylbenzoquinone (3,5-DTBQ) with molecular oxygen in two different solvents, methanol and acetonitrile. The study reveals that the catalytic activity is influenced by the solvent and to a significant extent by the backbone of the diamine and the behavior seems to be related mainly to steric rather than electronic factors. Experimental data suggest that a correlation, the lower the E(1/2) value the higher the catalytic activity, can be drawn between E(1/2) and Vmax of the complexes in a particular solvent. The EPR measurements suggest that the catalytic property of the complexes is related to the metal center(s) participation rather than to a radical mechanism. PMID:19809751

Banu, Kazi Sabnam; Chattopadhyay, Tanmay; Banerjee, Arpita; Mukherjee, Madhuparna; Bhattacharya, Santanu; Patra, Goutam Kumar; Zangrando, Ennio; Das, Debasis

2009-08-28

189

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

190

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

191

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.

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

1995-01-01

192

Production, properties and application to biocatalysis of a novel extracellular alkaline phenol oxidase from the thermophilic fungus Scytalidium thermophilum.  

PubMed

Scytalidium thermophilum produces an extracellular phenol oxidase on glucose-containing medium. Certain phenolic acids, specifically gallic acid and tannic acid, induce the expression of the enzyme. Production at 45 degrees C in batch cultures is growth-associated and is enhanced in the presence of 160 microM CuSO4 x 5 H2O and 3 mM gallic acid. The highest enzyme activity is observed at pH 7.5 and 65 degrees C, on catechol. When incubated for 1 h at pH 7 and pH 8, 95% and 86% of the activity is retained. Thermostability decreases gradually from 40 degrees C to 80 degrees C. Estimated molecular mass is c. 83 kDa, and pI is acidic at c. 5.4. Substrate specificity and inhibition analysis in culture supernatants suggest that the enzyme has unique properties showing activity towards catechol; 3,4-dihydroxy-L-phenylalanine (L-DOPA); 4-amino-N, N-diethylaniline (ADA); p-hydroquinone; gallic acid; tannic acid and caffeic acid, and no activity towards L-tyrosine, guaiacol, 2,2'-azino-bis(3-ethyl-benzthiazoline-6-sulphonic acid) (ABTS) and syringaldazine. Inhibition is observed in the presence of salicyl hydroxamic acid (SHAM) and p-coumaric acid. Enzyme activity is enhanced by cetyltrimethylammonium bromide (CTAB) and polyvinylpyrrolidone (PVP), and the organic solvents dimethyl sulfoxide (DMSO) and ethanol. No inhibition is observed in the presence of carbon monoxide. Benzoin, benzoyl benzoin and hydrobenzoin are converted into benzil, and stereoselective oxidation is observed on hydrobenzoin. The reported enzyme is novel due to its catalytic properties resembling mainly catechol oxidases, but displaying some features of laccases at the same time. PMID:16389559

Ogel, Z B; Yüzügüllü, Y; Mete, S; Bakir, U; Kaptan, Y; Sutay, D; Demir, A S

2006-01-03

193

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

194

A chemical proteomic probe for detecting dehydrogenases: catechol rhodanine.  

PubMed

Inherent complexity of the proteome often demands that it be studied as manageable subsets, termed subproteomes. A subproteome can be defined in a number of ways, although a pragmatic approach is to define it based on common features in an active site that lead to binding of a common small molecule ligand (e.g., a cofactor or a cross-reactive drug lead). The subproteome, so defined, can be purified using that common ligand tethered to a resin, with affinity chromatography. Affinity purification of a subproteome is described in the next chapter. That subproteome can then be analyzed using a common ligand probe, such as a fluorescent common ligand that can be used to stain members of the subproteome in a native gel. Here, we describe such a fluorescent probe, based on a catechol rhodanine acetic acid (CRAA) ligand that binds to dehydrogenases. The CRAA ligand is fluorescent and binds to dehydrogenases at pH > 7, and hence can be used effectively to stain dehydrogenases in native gels to identify what subset of proteins in a mixture are dehydrogenases. Furthermore, if one is designing inhibitors to target one or more of these dehydrogenases, the CRAA staining can be performed in a competitive assay format, with or without inhibitor, to assess the selectivity of the inhibitor for the targeted dehydrogenase. Finally, the CRAA probe is a privileged scaffold for dehydrogenases, and hence can easily be modified to increase affinity for a given dehydrogenase. PMID:22065218

Ge, Xia; Sem, Daniel S

2012-01-01

195

Polymorphism of catechol-o-methyltransferase and uterine leiomyoma.  

PubMed

Uterine leiomyoma (ULM) is the most common gynecological benign tumor that is affecting around 20-50 % of women over the age of 30. Although its molecular pathogenesis is still unknown, ULM has a multifactorial etiology determined by both genetics and environmental factors. The present study was designed to find out whether Val158Met polymorphism in the catechol-o-methyltransferase (COMT) gene is associated with the risk of ULM. We analyzed COMT Val158Met polymorphism in 105 ULMs patients and 105 healthy subjects using a polymerase chain reaction-based restriction fragment length polymorphism assay. We found remarkably similar frequencies in ULM compared with controls for COMT Val158Met genotypes and alleles, and no association was found between ULM and this polymorphism (p = 0.46). The COMT 158 Met allele in patients with large (?5 cm) fibroids was higher than in patients with small (<5 cm) fibroids, and significant association was found between fibroid size and COMT 158 Met allele (p = 0.011, OR 0.50, 95 %CI 0.28-0.90). Our results reflect that COMT Val158Met polymorphism is not associated with an increased risk of ULMs, but Val158Met polymorphism may be a risk factor for development of large fibroids in Turkish patients with ULM. PMID:23238870

Ates, Omer; Demirturk, Fazli; Toprak, Muhammet; Sezer, Saime

2012-12-14

196

Inhibition of human immunodeficiency virus integrase by bis-catechols.  

PubMed

The human immunodeficiency virus type 1 (HIV-1) integrase protein is required for the productive infection of T-lymphoid cells in culture (R. L. LaFemina, C. L. Schneider, H. L. Robbins, P. L. Callahan, K. LeGrow, E. Roth, W. A. Schleif, and E. A. Emini, J. Virol. 66:7414-7419, 1992). This observation suggests that chemical inhibitors of integrase may prevent the spread of HIV in infected individuals. In our search for such potential chemotherapeutic agents, we observed that beta-conidendrol inhibits both the sequence-dependent and sequence-independent endonucleolytic activities of integrase with comparable potencies in vitro (50% inhibitory concentration, 500 nM). Structurally related compounds tested for their abilities to inhibit integrase generated a limited structure-activity analysis which demonstrated that potency is associated with the bis-catechol structure: two pairs of adjacent hydroxyls on separate benzene rings. beta-Conidendrol did not inhibit several other endonucleases and/or phosphoryltransferases. Although beta-conidendrol was not effective in preventing HIV-1 infection in cell culture, the in vitro data demonstrate that it is possible to identify selective agents targeted against this essential HIV-1 function. PMID:7726489

LaFemina, R L; Graham, P L; LeGrow, K; Hastings, J C; Wolfe, A; Young, S D; Emini, E A; Hazuda, D J

1995-02-01

197

Plasmids for expression of heterologous proteins in Rhizopus oryzae  

Microsoft Academic Search

Rhizopus oryzae has long been used for enzyme production (e.g., glucoamylase and lipase), organic acid synthesis, and various fermented food applications. In this work, we describe a set of plasmid-based expression vectors that can be used for the production of heterologous proteins in R. oryzae. Three plasmid vectors have been created using either the glucoamylase A (amyA), pyruvate decarboxylase (pdcA),

Jeffrey A. Mertens; Christopher D. Skory; Ashraf S. Ibrahim

2006-01-01

198

Purification and characterization of polyphenol oxidase from fresh ginseng.  

PubMed

Polyphenol oxidase (PPO) was purified from fresh ginseng roots using acetone precipitation, carboxymethyl (CM)-Sepharose chromatography, and phenyl-Sepharose chromatography. Two isoenzymes (PPO 1 and PPO 2) were separated using an ion-exchange column with CM-Sepharose. PPO 1 was purified up to 13.2-fold with a 22.6% yield. PPO 2 bound to CM-Sepharose, eluted with NaCl, and was purified up to 22.5-fold with a 17.4% yield. PPO 2 was further chromatographed on phenyl-Sepharose. The molecular weight of the purified PPO 2 from fresh ginseng was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was about 40 kDa. The optimum temperature and pH were 20? and 7.0, respectively, using catechol as a substrate. Pyrogallol showed the highest substrate specificity. The effect of a PPO inhibitor showed that its activity increased slightly in the presence of a low concentration of citric acid. High concentrations of acidic compounds and sulfite agents significantly inhibited purified ginseng PPO 2. PMID:23717165

Kim, Jae-Joon; Kim, Woo-Yeon

2013-03-01

199

Nonhost resistance to Magnaporthe oryzae in Arabidopsis thaliana.  

PubMed

Rice blast, caused by Magnaporthe oryzae, is a devastating disease of rice (Oryza sativa). The mechanisms involved in resistance of rice to blast have been studied extensively and the rice--M. oryzae pathosystem has become a model for plant--microbe interaction studies. However, the mechanisms involved in nonhost resistance (NHR) of other plants to rice blast are still poorly understood. We have recently demonstrated that AGB1 and PMR5 contribute to PEN2-mediated preinvasion resistance to M. oryzae in Arabidopsis thaliana, suggesting a complex genetic network regulating the resistance. To determine whether other defense factors: RAR1, SGT1, and NHO1, affected the A. thaliana-M. oryzae interactions, double mutants were generated between pen2 and these defense-related mutants. All these double mutants exhibited a level of penetration resistance similar to that of the pen2 mutant, suggesting that none of these mutants significantly compromised resistance to M. oryzae in a pen2 background. PMID:20404515

Maeda, Kana; Houjyou, Yasunari; Komatsu, Takuma; Hori, Hiroki; Kodaira, Takahiro; Ishikawa, Atsushi

2010-06-01

200

Protein profile of rice (Oryza sativa) seeds  

PubMed Central

Seeds are the most important plant storage organ and play a central role in the life cycle of plants. Since little is known about the protein composition of rice (Oryza sativa) seeds, in this work we used proteomic methods to obtain a reference map of rice seed proteins and identify important molecules. Overall, 480 reproducible protein spots were detected by two-dimensional electrophoresis on pH 4–7 gels and 302 proteins were identified by MALDI-TOF MS and database searches. Together, these proteins represented 252 gene products and were classified into 12 functional categories, most of which were involved in metabolic pathways. Database searches combined with hydropathy plots and gene ontology analysis showed that most rice seed proteins were hydrophilic and were related to binding, catalytic, cellular or metabolic processes. These results expand our knowledge of the rice proteome and improve our understanding of the cellular biology of rice seeds.

Yang, Yanhua; Dai, Li; Xia, Hengchuan; Zhu, Keming; Liu, Haijun; Chen, Keping

2013-01-01

201

A mutation in the Xanthomonas oryzae pv. oryzae wxoD gene affects xanthan production and chemotaxis.  

PubMed

Xanthomonas oryzae pv. oryzae causes bacterial blight in rice (Oryza sativa L.). The effect of a mutation in the wxoD gene, that encodes a putative O-antigen acetylase, on xanthan production as well as bacterial chemotaxis was investigated. The mutation increased xanthan production by 52 %. The mutant strain was non-motile on semi-solid agar swarm plates. In addition, several genes involved in chemotaxis, including the cheW, cheV, cheR, and cheD genes, were down-regulated by a mutation in the wxoD gene. Thus, the mutation in the wxoD gene affects xanthan production as well as bacterial chemotaxis. However, the wxoD gene is not essential for the virulence of X. oryzae. PMID:23881323

Nam, Jae-Young; Kim, Hong-Il; Lee, Chang-Soo; Park, Young-Jin

2013-07-24

202

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

PubMed

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-E(2) and 4-OH-E(2), 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 acid each inhibited the O-methylation of 2-OH-E(2) in a concentration-dependent manner, with IC(50) values of 1.3-1.4 and 6.3-12.5 microM, respectively, and they also inhibited the O-methylation of 4-OH-E(2), with IC(50) values of 0.7-0.8 and 1.3-3.1 microM, respectively. Similar inhibition pattern was seen with human placental COMT preparation. CAPE had a comparable effect as caffeic acid for inhibiting the O-methylation of 2-OH-E(2), but it exerted a weaker inhibition of the O-methylation of 4-OH-E(2). Enzyme kinetic analyses showed that chlorogenic acid and caffeic acid inhibited the human liver and placental COMT-mediated O-methylation of catechol estrogens with a mixed mechanism of inhibition (competitive plus noncompetitive). Computational molecular modeling analysis showed that chlorogenic acid and caffeic acid can bind to human soluble COMT at the active site in a similar manner as the catechol estrogen substrates. Moreover, the binding energy values of these two coffee polyphenols are lower than that of catechol estrogens, which means that coffee polyphenols have higher binding affinity for the enzyme than the natural substrates. This computational finding agreed perfectly with our biochemical data. PMID:19095062

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

2008-11-28

203

Purification and partial biochemical characterization of polyphenol oxidase from mamey (Pouteria sapota).  

PubMed

While a long shelf life for fruit products is highly desired, enzymatic browning is the main cause of quality loss in fruits and is therefore a main problem for the food industry. In this study polyphenol oxidase (PPO), the main enzyme responsible for browning was isolated from mamey fruit (Pouteria sapota) and characterized biochemically. Two isoenzymes (PPO 1 and PPO 2) were obtained upon ammonium sulfate precipitation and hydrophobic and ion exchange chromatography; PPO 1 was purified up to 6.6-fold with 0.28% yield, while PPO 2 could not be characterized as enzyme activity was completely lost after 24 h of storage. PPO 1 molecular weight was estimated to be 16.1 and 18 kDa by gel filtration and SDS-PAGE, respectively, indicating that the native state of the PPO 1 is a monomer. The optimum pH for PPO 1 activity was 7. The PPO 1 was determined to be maximum thermally stable up to 35°C. Kinetic constants for PPO 1 were K(m)=44 mM and K(m)=1.3 mM using catechol and pyrogallol as substrate, respectively. The best substrates for PPO 1 were pyrogallol, 4-methylcatechol and catechol, while ascorbic acid and sodium metabisulfite were the most effective inhibitors. PMID:21087780

Palma-Orozco, Gisela; Ortiz-Moreno, Alicia; Dorantes-Alvarez, Lidia; Sampedro, José G; Nájera, Hugo

2010-11-17

204

Purification and partial characterization of polyphenol oxidase from the flower buds of Lonicera japonica Thunb.  

PubMed

The purification and partial enzymology characteristics of polyphenol oxidase from Lonicera japonica (LjPPO) were studied in this paper. The crude enzyme solution was purified in turn by ammonium sulfate, dialysis, and DEAE-cellulose ion-exchange chromatography after preliminary treatments. Purification resulted in 31-fold enrichment and its molecular weight was estimated to be ~49 kDa exhibited on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The pH for optimal conditions of LjPPO was 7.5, and the temperature was 25 °C, in addition, the inhibitive effects of inhibitors were enhanced positively with increasing of the concentration. Moreover, crude enzyme solution showed diphenolase activity toward catechol, l-dopa and chlorogenic acid rather than monophenolase and triphenolase activity, and the best substrate was catechol because of the highest V(max)/K(m) value. However, the oxidation of diphenol related to browning significantly, so the data obtained in this research provided theoretical basis for the prevention of enzymatic browning of L. japonica during processing. PMID:23265514

Liu, Na-na; Liu, Wei; Wang, Dai-jie; Zhou, Yi-bin; Lin, Xiao-jing; Wang, Xiao; Li, Sheng-bo

2012-11-10

205

Oxidation of phenolic compounds by the bifunctional catalase-phenol oxidase (CATPO) from Scytalidium thermophilum.  

PubMed

The thermophilic fungus Scytalidium thermophilum produces a novel bifunctional catalase with an additional phenol oxidase activity (CATPO); however, its phenol oxidation spectrum is not known. Here, 14 phenolic compounds were selected as substrates, among which (+)-catechin, catechol, caffeic acid, and chlorogenic acid yielded distinct oxidation products examined by reversed-phase HPLC chromatography method. Characterization of the products by LC-ESI/MS and UV-vis spectroscopy suggests the formation of dimers of dehydrocatechin type B (hydrophilic) and type A (hydrophobic), as well as oligomers, namely, a trimer and tetramer from (+)-catechin, the formation of a dimer and oligomer of catechol, a dimer from caffeic acid with a caffeicin-like structure, as well as trimeric and tetrameric derivatives, and a single major product from chlorogenic acid suggested to be a dimer. Based on the results, CATPO oxidizes phenolic compounds ranging from simple phenols to polyphenols but all having an ortho-diphenolic structure in common. The enzyme also appears to have stereoselectivity due to the oxidation of (+)-catechin, but not that of epicatechin. It is suggested that CATPO may contribute to the antioxidant mechanism of the fungus and may be of value for future food and biotechnology applications where such a bifunctional activity would be desirable. PMID:22370948

Koclar Avci, Gulden; Coruh, Nursen; Bolukbasi, Ufuk; Ogel, Zumrut B

2012-02-28

206

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

2012-09-07

207

A “defeated” rice resistance gene acts as a QTL against a virulent strain of Xanthomonas oryzae pv. oryzae  

Microsoft Academic Search

The genetic components responsible for qualitative and quantitative resistance of rice plants to three strains (CR4, CXO8,\\u000a and CR6) of Xanthomonas oryzae pv. oryzae (Xoo) were investigated using a set of 315 recombinant inbred lines (RILs) from the cross Lemont (japonica) × Teqing (indica) and a complete linkage map with 182 well distributed RFLP markers. We mapped a major gene

Z.-K. Li; L. J. Luo; H. W. Mei; A. H. Paterson; X. H. Zhao; D. B. Zhong; Y. P. Wang; X. Q. Yu; L. Zhu; R. Tabien; J. W. Stansel; C. S. Ying

1999-01-01

208

Analysis of catRABC operon for catechol degradation from phenol-degrading Rhodococcus erythropolis.  

PubMed

The gene cluster catRABC, involved in catechol degradation, was isolated from Rhodococcus erythropolis CCM2595. The genes catA, catB, catC, and the divergently transcribed catR code for catechol 1,2-dioxygenase, cis,cis-muconate cycloisomerase, muconolactone isomerase, and an IclR-type transcriptional regulator, respectively. Measurements of catechol 1,2-dioxygenase activity showed that the expression of catA is induced by phenol but not by catechol or cis,cis-muconate. The activity of catechol 1,2-dioxygenase was repressed by succinate, but no repression by glucose was observed. The transcription start points of catA and catR were determined by primer extension analysis, and the respective promoters (P-catA and P-catR) were thus localized. Measurements of promoter activity during batch cultivation using transcriptional fusion with the gfpuv reporter gene showed that expression of the catR-catABC operon is regulated at the level of transcription. Both P-catR and P-catA are repressed by CatR, and the induction of P-catA by phenol is maintained in the absence of the repressor (in R. erythropolis DeltacatR). Two different potential binding sites for the IclR-type regulator and a recognition site for the cyclic AMP receptor protein (CRP) were identified within the intergenic region between catR and catA. PMID:17483937

Veselý, M; Knoppová, M; Nesvera, J; Pátek, M

2007-05-05

209

Catechol-modified activated carbon prepared by the diazonium chemistry for application as active electrode material in electrochemical capacitor.  

PubMed

Activated carbon (Black Pearls 2000) modified with electroactive catechol groups was evaluated for charge storage application as active composite electrode material in an aqueous electrochemical capacitor. High surface area Black Pearls 2000 carbon was functionalized by introduction of catechol groups by spontaneous reduction of catechol diazonium ions in situ prepared in aqueous solution from the corresponding amine. Change in the specific surface area and pore texture of the carbon following grafting was monitored by nitrogen gas adsorption measurements. The electrochemical properties and the chemical composition of the catechol-modified carbon electrodes were investigated by cyclic voltammetry. Such carbon-modified electrode combines well the faradaic capacitance, originating from the redox activity of the surface immobilized catechol groups, to the electrochemical double layer capacitance of the high surface area Black Pearls carbon. Due to the faradaic contribution, the catechol-modified electrode exhibits a higher specific capacitance (250 F/g) than pristine carbon (150 F/g) over a potential range of -0.4 to 0.75 V in 1 M H(2)SO(4). The stability of the modified electrode evaluated by long-time charge/discharge cycling revealed a low decrease of the capacitance of the catechol-modified carbon due to the loss of the catechol redox activity. Nonetheless, it was demonstrated that the benefit of redox groups persists for 10,?000 constant current charge/discharge cycles. PMID:22803766

Pognon, Grégory; Cougnon, Charles; Mayilukila, Dilungane; Bélanger, Daniel

2012-07-30

210

Anaerobic Metabolism of Catechol by the Denitrifying Bacterium Thauera aromatica--a Result of Promiscuous Enzymes and Regulators?  

Microsoft Academic Search

The anaerobic metabolism of catechol (1,2-dihydroxybenzene) was studied in the betaproteobacterium Thauera aromatica that was grown with CO2 as a cosubstrate and nitrate as an electron acceptor. Based on different lines of evidence and on our knowledge of enzymes and genes involved in the anaerobic metabolism of other aromatic substrates, the following pathway is proposed. Catechol is converted to catechylphosphate

Bin Ding; Sirko Schmeling; Georg Fuchs

2008-01-01

211

Synthesis, structural elucidation, and stereochemistry of five-coordinate organoarsenic catecholates  

SciTech Connect

The synthesis of five-coordinate organoarsenic catecholates, with substitution of 3-CH/sub 3/, 4-CH/sub 3/OC(==O); 4,5-C/sub 6/H/sub 4/, and 3,3'-C(==O)NH(CH/sub 2/)/sub 4/NHC(==O) groups on the catechol ring and CH/sub 3/ or Ph (phenyl) on arsenic, was performed. These reactions provided new insight into the structures and stereochemistry of these organoarsenic compounds. In one case, 3-methylcatecholate of phenylarsonic acid, a single-crystal x-ray analysis provided unequivocal evidence for cis stersochemistry of the methyl groups on the catechol rings, an essentially rectangular-pyramidal configuration around arsenic, and a preferred conformation of the phenyl group in relation to the oxygens surrounding the arsenic atom.

Fish, R.H.; Tannous, R.S.

1982-01-01

212

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.

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

213

Radiochemical high-performance liquid chromatographic assay for the determination of catechol O-methyltransferase activity towards various substrates.  

PubMed

A new chromatographic catechol O-methyltransferase (COMT) assay based on S-adenosyl-L-[methyl-14C]methionine and on-line radioactivity detection was developed. With minor modifications in the mobile phase composition the methylation velocities for 30 structurally diverse compounds including simple catechols, neurotransmitters, catecholestrogens and catecholic drugs could be measured using human and rat recombinant soluble COMT. The enzymes showed very similar substrate selectivities. The radiochemical method was validated using 3,4-dihydroxybenzoic acid as a model substrate and it was shown that accurate and reproducible methylation velocity values could be achieved for both of the catecholic hydroxyls. The method proved to be suited for determining the enzyme kinetic parameters and can probably be further used for gathering enzyme kinetic data on differentially substituted catechols in order to construct proper structure-activity relationships for COMT. PMID:10676994

Lautala, P; Ulmanen, I; Taskinen, J

1999-12-24

214

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

215

Prokaryotic origins for the mitochondrial alternative oxidase and plastid terminal oxidase nuclear genes  

Microsoft Academic Search

The mitochondrial alternative oxidase is a diiron carboxylate quinol oxidase (Dox) found in plants and some fungi and protists, but not animals. The plastid terminal oxidase is distantly related to alternative oxidase and is most likely also a Dox protein. Database searches revealed that the ?-proteobacterium Novosphingobium aromaticivorans and the cyanobacteria Nostoc sp. PCC7120, Synechococcus sp. WH8102 and Prochlorococcus marinus

Patrick M Finnegan; Ann L Umbach; Jackie A Wilce

2003-01-01

216

Origins, evolutionary history, and taxonomic distribution of alternative oxidase and plastoquinol terminal oxidase  

Microsoft Academic Search

Alternative oxidase (AOX) and plastoquinol terminal oxidase (PTOX) are related quinol oxidases associated with respiratory and photosynthetic electron transport chains, respectively. Contrary to previous belief, AOX is present in numerous animal phyla, as well as heterotrophic and marine phototrophic proteobacteria. PTOX appears limited to organisms capable of oxygenic photosynthesis, including cyanobacteria, algae and plants. We propose that both oxidases originated

Allison E. McDonald; Greg C. Vanlerberghe

2006-01-01

217

Isolation and characterization of a second glucoamylase gene without a starch binding domain from Rhizopus oryzae  

Microsoft Academic Search

Work with Rhizopus oryzae previously suggested that this filamentous fungus only had one glucoamylase gene. 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-I strain, was confirmed by Southern blot analysis, restriction mapping, and sequencing. Sequence analysis

Jeffrey A. Mertens; Christopher D. Skory

2007-01-01

218

Effect of Aspergillus oryzae Extract Alone or in Combination with Antimicrobial Compounds on Ruminal Bacteria1  

Microsoft Academic Search

The effect of an Aspergillus oryzae fermentation extract on the growth rates of pure cultures of rumi- nal bacteria was determined. Bacteria were grown in an anaerobic ruminal fluid and carbohydrate medium. A sterile filtrate made with 10% A. oryzae was added to the medium at 2 or 5% (vol\\/vol) to provide a final A. oryzae concentration of 2 or

A. A. Beharka; T. G. Nagaraja

1998-01-01

219

Catechol 1,2-dioxygenase from ?-naphthol degrading thermophilic Geobacillus sp. strain: purification and properties  

Microsoft Academic Search

The purpose of this study was purification and characterization of catechol 1,2-dioxygenase from Geobacillus sp. G27 strain, which degrades ?-naphthol by the ?-ketoadipate pathway. The catechol 1,2-dioxygenase (C1,2O) was purified\\u000a using four steps of ammonium sulfate precipitation, DEAE-celullose, Sephadex G-150 and hydroxylapatite chromatographies. The\\u000a enzyme was purified about 18-fold with a specific activity of 7.42 U mg of protein?1. The

Gražina Giedraityte; Lilija Kal?dien?

2009-01-01

220

Intramolecular interactions in ortho-methoxyalkylphenylboronic acids and their catechol esters.  

PubMed

Catechol esters of ortho-methoxyalkylphenylboronic acids have been synthesized and characterized by (17)O NMR spectroscopy. The results were compared with the data for the parent acids. The influence of intramolecular and intermolecular hydrogen bonds on the properties of the boronic acids has been discussed. The (17)O NMR data for the boronic esters proved that there are no O?B interactions in the investigated compounds. This fact is connected with weak Lewis acidity of the parent acids and their low sugars' receptors activity. Crystal structure of ortho-methoxyphenylboronic acid catechol ester was determined. PMID:23978747

Adamczyk-Wo?niak, Agnieszka; Borys, Krzysztof M; Czerwi?ska, Karolina; Gierczyk, B?a?ej; Jakubczyk, Micha?; Madura, Izabela D; Sporzy?ski, Andrzej; Tomecka, Ewelina

2013-08-08

221

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

Rentero, N; Kitahama, K; Quintin, L

1993-01-01

222

Abiotic transformation of catechol and 1-naphthol in aqueous solution-influence of environmental factors.  

PubMed

The abiotic transformation of catechol and 1-naphthol singly and in mixtures was tested in sterile Tris-HCl buffer with regard to several environmental factors including temperature (7 degrees C, 20 degrees C and 30 degrees C), lighting conditions, pH (between 7.0 and 8.5) and dissolved oxygen (at partial pressures of 0.0, 220, 2200, 11000 and 22000 Pa). Irrespective of lighting conditions. catechol autoxidation was confirmed in aerated medium with a rate independent of the presence of 1-naphthol but proportional to the dissolved oxygen concentration, to the pH (its half-disappearance occurred in 24h at pH 8.5) and, to a lesser extent, to the incubating temperature (at 20 degrees C, 20% disappeared in 10 days at pH 7.0). Under alkaline conditions, the reaction of the anionic form (catecholate) with an equimolar concentration of molecular oxygen (O2) led presumably to hydrogen peroxide anion (HO2-) and coloured polymerization products. When tested alone, 1-naphthol was not significantly influenced either by lighting conditions, incubating temperature or dissolved oxygen concentration. It was also found to be quite stable with respect to pH, with a 15-fold weaker transformation rate than for catechol at the highest pH used. When tested in a mixture with catechol, 1-naphthol was found to be involved in a new chemical oxidation reaction catalyzed by catecholate. The transformation of one mole of 1-naphthol consumes four moles of oxygen. In the presence of catechol, the stoichiometry of the 1-naphthol transformation, under the influence of oxygen, suggests the possible formation of 2,5,6,8-tetrahydroxy 1,4-naphthoquinone via Lawsone (2-hydroxy 1,4-naphthoquinone) and naphthopurpurine (2,5,8-trihydroxy 1,4-naphthoquinone) as hypothetic intermediates. This is the first report of the autoxidation of 1-naphthol, catalyzed by catechol, in aqueous solution, in the absence of UV irradiation. PMID:11561636

Borraccino, R; Kharoune, M; Giot, R; Agathos, S N; Nyns, E J; Naveau, H P; Pauss, A

2001-10-01

223

Plasma Activation of Integrated Carbon Nanotube Electrodes for Electrochemical Detection of Catechol  

NASA Astrophysics Data System (ADS)

In this study, integrated multi-wall carbon nanotube (MWCNT) electrodes were prepared in the holes of glass directly by microwave plasma chemical vapour deposition (MWPCVD). The electrochemical behaviour of catechol at the integrated MWCNT electrodes was investigated. The oxygen plasma treated CNT electrodes had better electrochemical performance for the analysis of catechol than that of as-synthesized CNT electrodes. Both the as-synthesized CNTs and plasma treated CNTs were characterized by TEM(transmission electron microscopy, XPS(X-ray photoelectron spectroscopy) and Raman spectroscopy. The results revealed that the oxygen plasma activation is an effective method to enhance the electrochemical properties of CNT electrodes.

Wang, Shenggao; Wang, Tao; Li, Yanqiong; Zhao, Xiujian; Han, Jianjun; Wang, Jianhua

2007-04-01

224

Determination of some catechol derivatives by a flow injection electrochemiluminescent inhibition method  

Microsoft Academic Search

A flow injection electrochemiluminescent inhibition method has been developed for the determination of some catechol derivatives based on studying the inhibition phenomena of these compounds to the electrochemiluminescence of luminol. The linear calibration range of 5×10?8 to 1×10?5, 5×10?8 to 1×10?5 and 1×10?8 to 5×10?5 mol l?1, the detection limit of 1.2×10?8, 2.1×10?8 and 5.2×10?9 mol l?1were obtained for catechol,

Yu-Gang Sun; Hua Cui; Ying-Hui Li; Xiang-Qin Lin

2000-01-01

225

A transposon insertion in the gumG homologue of Xanthomonas oryzae pv. oryzae causes loss of extracellular polysaccharide production and virulence.  

PubMed

Xanthomonas oryzae pv. oryzae causes a serious disease of rice called bacterial leaf blight. It produces copious amounts of extracellular polysaccharide (EPS). An EPS- and virulence-deficient mutant of X. oryzae pv. oryzae was isolated by Tn5 mutagenesis. The mutant allele in this strain was cloned by transposon tagging in the Escherichia coli vector pBluescript and the DNA sequences flanking the transposon insertion site were determined. Computer-based similarity searches in the DNA database using the BLAST algorithm showed these sequences to be 78% identical at the nucleotide level to a gene, gumG, in the gum cluster, which is required for EPS biosynthesis in Xanthomonas campestris pv. campestris. A 36-kb X. oryzae pv. oryzae genomic clone containing the putative EPS biosynthetic gene cluster of X. oryzae pv. oryzae restored both EPS production and virulence proficiency to the gumGXo::Tn5 mutant. The results suggest that EPS is an important virulence factor of X. oryzae pv. oryzae. PMID:10481086

Dharmapuri, S; Sonti, R V

1999-10-01

226

The bacterial cytochrome cbb 3 oxidases  

Microsoft Academic Search

Cytochrome cbb3 oxidases are found almost exclusively in Proteobacteria, and represent a distinctive class of proton-pumping respiratory heme-copper oxidases (HCO) that lack many of the key structural features that contribute to the reaction cycle of the intensely studied mitochondrial cytochrome c oxidase (CcO). Expression of cytochrome cbb3 oxidase allows human pathogens to colonise anoxic tissues and agronomically important diazotrophs to

Robert S. Pitcher; Nicholas J. Watmough

2004-01-01

227

Transmembrane proton translocation by cytochrome c oxidase  

Microsoft Academic Search

Respiratory heme-copper oxidases are integral membrane proteins that catalyze the reduction of molecular oxygen to water using electrons donated by either quinol (quinol oxidases) or cytochrome c (cytochrome c oxidases, CcOs). Even though the X-ray crystal structures of several heme-copper oxidases and results from functional studies have provided significant insights into the mechanisms of O2-reduction and, electron and proton transfer,

Gisela Brändén; Robert B. Gennis; Peter Brzezinski

2006-01-01

228

Amine oxidases in apoptosis and cancer  

Microsoft Academic Search

Amine oxidases, the major enzymes of biogenic amines metabolism, are considered to be biological regulators, especially for cell growth and differentiation. A primary involvement of amine oxidases in cancer growth inhibition and progression, especially by means of aldehydes, H2O2 and other reactive oxygen species, the amine oxidase-mediated products of biogenic amines oxidation, has been demonstrated.Amine oxidases are involved in cancer

Antonio Toninello; Paola Pietrangeli; Umberto De Marchi; Mauro Salvi; Bruno Mondově

2006-01-01

229

Trichoderma harzianum: a biocontrol agent against Bipolaris oryzae.  

PubMed

Rice brown spot, caused by Bipolaris oryzae, can be a serious disease causing a considerable yield loss. Trichoderma harzianum is an effective biocontrol agent for a number of plant fungal diseases. Thus, this research was carried out to investigate the mechanisms of action by which T. harzianum antagonizes Bipolaris oryzae in vitro, and the efficacy of spray application of a spore suspension of T. harzianum for control of rice brown spot disease under field conditions. In vitro, the antagonistic behavior of T. harzianum resulted in the overgrowth of B. oryzae by T. harzianum, while the antifungal metabolites of T. harzianum completely prevented the linear growth of B. oryzae. Light and scanning electron microscope (SEM) observations showed no evidence that mycoparasitism contributed to the aggressive nature of the tested isolate of T. harzianum against B. oryzae. Under field conditions, spraying of a spore suspension of T. harzianum at 10(8)spore ml(-1) significantly reduced the disease severity (DS) and disease incidence (DI) on the plant leaves, and also significantly increased the grain yield, total grain carbohydrate, and protein, and led to a significant increase in the total photosynthetic pigments (chlorophyll a and b and carotenoids) in rice leaves. PMID:17592758

Abdel-Fattah, Gamal M; Shabana, Yasser M; Ismail, Adel E; Rashad, Younes Mohamed

2007-06-26

230

EcpA, an extracellular protease, is a specific virulence factor required by Xanthomonas oryzae pv. oryzicola but not by X. oryzae pv. oryzae in rice  

Technology Transfer Automated Retrieval System (TEKTRAN)

Previously, twelve protease-deficient mutants of Xanthomonas oryzae pv. oryzicola (Xoc) RS105 strain were recovered from a Tn5-tagged mutant library. In the current study, the Tn5 insertion site in each mutant was mapped. Mutations in genes encoding components of the type II secretion apparatus, cAM...

231

[Oxidase gene from sweetpotato].  

PubMed

Polyphenol oxidase is the enzyme responsible for enzymatic browning in sweetpotato that decreases the commercial value of sweetpotato products. Here we reported the cloning and characterization of a new cDNA encoding PPO from sweetpotato, designated as IbPPO (GeneBank accession number: AY822711). The full-length cDNA of IbPPO is 1984 bp with a 1767 bp open reading frame (ORF) encoding a 588 amino acid polypeptide with calculated molecular weight of 65.7 kDa and theoretical pI of 6.28. The coding sequence of IbPPO was also directly amplified from the genomic DNA of sweetpotato that demonstrated that IbPPO was an intron-free gene. The computational comparative analysis revealed that IbPPO showed homology to other PPOs of plant origin and contained a 50 amino acid plastidial transit peptides at its N-terminal and the two conserved CuA and CuB copper-binding motifs in the catalytic region of IbPPO. A highly conserved serine-rich motif was firstly found in the transit peptides of plant PPO enzymes. Then the homology-based structural modeling of IbPPO showed that IbPPO had the typical structure of PPO: the catalytic copper center was accommodated in a central four-helix bundle located in a hydrophobic pocket close to the surface. Finally, the results of the semi-quantitative RT-PCR analysis of IbPPO in different tissues demonstrated that IbPPO could express in all the organs of sweetpotato including: mature leaves, young leaves, the stems of mature leaves (petioles), the storage roots and the veins but at different levels. The highest-level expression of IbPPO was found in veins, followed by storage roots, young leaves and mature leaves; and the lowest-level expression of IbPPO was found in petioles. The present researches will facilitate the development of anti-brown sweetpotato by genetic engineering. PMID:17209428

Liao, Zhihua; Chen, Rong; Chen, Min; Yang, Yijian; Fu, Yufan; Zhang, Qitang; Lan, Xiaozhong

232

The Oryza Map Alignment Project: The Golden Path to Unlocking the Genetic Potential of Wild Rice Species  

Microsoft Academic Search

The wild species of the genus Oryza offer enormous potential to make a significant impact on agricultural productivity of the cultivated rice species Oryza sativa and Oryza glaberrima. To unlock the genetic potential of wild rice we have initiated a project entitled the ‘Oryza Map Alignment Project’ (OMAP) with the ultimate goal of constructing and aligning BAC\\/STC based physical maps

Rod A. Wingl; Jetty S. S. Ammiraju; Meizhong Luo; HyeRan Kim; Yeisoo Yu; Dave Kudrna; Jose L. Goicoechea; Wenming Wang; Will Nelson; Kiran Rao; Darshan Brar; Dave J. Mackill; Bin Han; Cari Soderlund; Lincoln Stein; Phillip SanMiguel; Scott Jackson

2005-01-01

233

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

2013-02-01

234

Biosynthesis of Silver Nanoparticles by Phytopathogen Xanthomonas oryzae pv. oryzae Strain BXO8.  

PubMed

Extracellular biogenic synthesis of silver nanoparticles with various shapes using the rice bacterial blight bacterium Xanthomonas oryzae pv. oryzae BXO8 is reported. The synthesized silver nanoparticles were characterized by UV-Vis spectroscopy, powder X-ray diffractometry (XRD), scanning electron microscopy, energy dispersive X-ray spectrometry, and highresolution transmission electron microscopy (HR-TEM). Based on the evidence of HR-TEM, the synthesized particles were found to be spherical, with anisotropic structures such as triangles and rods, with an average size of 14.86 nm. The crystalline nature of silver nanoparticles was evident from the bright circular spots in the SAED pattern, clear lattice fringes in the high-resolution TEM images, and peaks in the XRD pattern. The FTIR spectrum showed that biomolecules containing amide and carboxylate groups are involved in the reduction and stabilization of the silver nanoparticles. Using such a biological method for the synthesis of silver nanoparticles is a simple, viable, cost-effective, and environmentally friendly process, which can be used in antimicrobial therapy. PMID:23751558

Narayanan, Kannan Badri; Sakthivel, Natarajan

2013-09-28

235

Differential requirement of Oryza sativa RAR1 in immune receptor-mediated resistance of rice to Magnaporthe oryzae.  

PubMed

The required for Mla12 resistance (RAR1) protein is essential for the plant immune response. In rice, a model monocot species, the function of Oryza sativa RAR1 (OsRAR1) has been little explored. In our current study, we characterized the response of a rice osrar1 T-DNA insertion mutant to infection by Magnaporthe oryzae, the causal agent of rice blast disease. osrar1 mutants displayed reduced resistance compared with wild type rice when inoculated with the normally virulent M. oryzae isolate PO6-6, indicating that OsRAR1 is required for an immune response to this pathogen. We also investigated the function of OsRAR1 in the resistance mechanism mediated by the immune receptor genes Pib and Pi5 that encode nucleotide binding-leucine rich repeat (NB-LRR) proteins. We inoculated progeny from Pib/osrar1 and Pi5/osrar1 heterozygous plants with the avirulent M. oryzae isolates, race 007 and PO6-6, respectively. We found that only Pib-mediated resistance was compromised by the osrar1 mutation and that the introduction of the OsRAR1 cDNA into Pib/osrar1 rescued Pib-mediated resistance. These results indicate that OsRAR1 is required for Pib-mediated resistance but not Pi5-mediated resistance to M. oryzae. PMID:23563801

Song, Min-Young; Kim, Chi-Yeol; Han, Muho; Ryu, Hak-Seung; Lee, Sang-Kyu; Sun, Li; He, Zuhua; Seo, Young-Su; Canal, Patrick; Ronald, Pamela C; Jeon, Jong-Seong

2013-04-05

236

Biochemical and computational insights into the anti-aromatase activity of natural catechol estrogens  

Microsoft Academic Search

High levels of endogenous estrogens are associated with increased risks of breast cancer. Estrogen levels are mainly increased by the activity of the aromatase enzyme and reduced by oxidative\\/conjugative metabolic pathways. In this paper, we demonstrate for the first time that catechol estrogen metabolites are potent aromatase inhibitors, thus establishing a link between aromatase activity and the processes involved in

Marco A. C. Neves; Teresa C. P. Dinis; Giorgio Colombo; M. Luisa Sá e Melo

2008-01-01

237

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…

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

2009-01-01

238

Salicylate and catechol levels are maintained in nahG transgenic poplar  

Technology Transfer Automated Retrieval System (TEKTRAN)

Metabolic profiling was used to investigate the molecular phenotypes of transgenic Populus tremula x P. alba bybrids expressing the nahG transgene, a bacterial gene encoding salicylate hydroxylase that converts salicylic acid to catechol. Despite the efficacy of this transgenic approach to reducing...

239

Studies on charge distribution and valence tautomerism in transition metal complexes of catecholate and semiquinonate ligands  

Microsoft Academic Search

Transition metal complexes containing first row metal ions chelated by catecholate (Cat) and semiquinonate (SQ) ligands have been found to have localized electronic structures with quinone ligands bonded in both SQ and Cat electronic forms. In exceptional cases the balance of metal and quinone orbital energies is sufficiently close as to permit magnetic and spectroscopic observations on isomers differing in

Cortlandt G. Pierpont

2001-01-01

240

Role of Catecholate Siderophores in Gram-Negative Bacterial Colonization of the Mouse Gut  

PubMed Central

We investigated the importance of the production of catecholate siderophores, and the utilization of their iron (III) complexes, to colonization of the mouse intestinal tract by Escherichia coli. First, a ?tonB strain was completely unable to colonize mice. Next, we compared wild type E. coli MG1655 to its derivatives carrying site-directed mutations of genes for enterobactin synthesis (?entA::Cm; strain CAT0), ferric catecholate transport (?fiu, ?fepA, ?cir, ?fecA::Cm; CAT4), or both (?fiu, ?fepA, ?fecA, ?cir, ?entA::Cm; CAT40) during colonization of the mouse gut. Competitions between wild type and mutant strains over a 2-week period in vivo showed impairment of all the genetically engineered bacteria relative to MG1655. CAT0, CAT4 and CAT40 colonized mice 101-, 105-, and 102-fold less efficiently, respectively, than MG1655. Unexpectedly, the additional inability of CAT40 to synthesize enterobactin resulted in a 1000-fold better colonization efficiency relative to CAT4. Analyses of gut mucus showed that CAT4 hyperexcreted enterobactin in vivo, effectively rendering the catecholate transport-deficient strain iron-starved. The results demonstrate that, contrary to prior reports, iron acquisition via catecholate siderophores plays a fundamental role in bacterial colonization of the murine intestinal tract.

Pi, Hualiang; Jones, Shari A.; Mercer, Lynn E.; Meador, Jessica P.; Caughron, Joyce E.; Jordan, Lorne; Newton, Salete M.; Conway, Tyrrell; Klebba, Phillip E.

2012-01-01

241

Salicylate and catechol levels are maintained in nahG transgenic poplar  

Microsoft Academic Search

Metabolic profiling was used to investigate the molecular phenotypes of a transgenic Populus tremula×P. alba hybrid expressing the nahG transgene, a bacterial gene encoding salicylate hydroxylase that converts salicylic acid to catechol. Despite the efficacy of this transgenic approach to reduce salicylic acid levels in other model systems and thereby elucidate roles for salicylic acid in plant signaling, transgenic poplars

Alison M. Morse; Timothy J. Tschaplinski; Christopher Dervinis; Paula M. Pijut; Eric A. Schmelz; Wendy Day; John M. Davis

2007-01-01

242

Degradation of catechol by ionizing radiation, ozone and the combined process ozone-electron-beam  

NASA Astrophysics Data System (ADS)

The influence of oxygen on the radiation-induced degradation of catechol (5×10-4moldm-3, 55mgdm-3) in distilled water was studied by gamma-radiolysis in the presence of air (A) and using air saturation (AS) during irradiation. Under AS conditions a complete decomposition of catechol as well as of the trihydroxybenzene products was obtained by a dose of 6kGy, without air saturation all phenolic compounds were still present at 10kGy. Using AS, at 12kGy the total organic carbon (TOC) was reduced by 63%, without air saturation by 17.5%. Detoxification was only obtained in AS solutions. In the presence of the natural matrix of the local tap water no trihydroxybenzene products were formed and for total decomposition of catechol in AS solutions 9kGy were required. The comparison of the effectiveness of an electron beam (EB), an ozone (O3) and a combined EB/O3 process showed, that by EB/O3 the extent of catechol degradation corresponded to the sum of the decay with EB and with ozone, whereas for the chemical oxygen demand and TOC reduction a synergistic effect was evident.

Kubesch, K.; Zona, R.; Solar, S.; Gehringer, P.

2005-03-01

243

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

PubMed Central

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.

Klecka, G M; Gibson, D T

1981-01-01

244

Variations in catechol- O-methyltransferase gene interact with parenting to influence attention in early development  

Microsoft Academic Search

Attention influences many aspects of cognitive development. Variations in the catechol-O-methyltransferase (COMT) gene, known to affect dopamine neurotransmission, have frequently been found to influence attention in adults and older children. In this paper we examined 2 year old children and found that variation in the COMT gene influenced attention in a task involving looking to a sequence of visual stimuli.

P. Voelker; B. E. Sheese; M. K. Rothbart; M. I. Posner

2009-01-01

245

Two Genomic Regions Involved in Catechol Siderophore Production by Erwinia carotovora  

PubMed Central

Two regions involved in catechol biosynthesis (cbs) of Erwinia carotovora W3C105 were cloned by functional complementation of Escherichia coli mutants that were deficient in the biosynthesis of the catechol siderophore enterobactin (ent). A 4.3-kb region of genomic DNA of E. carotovora complemented the entB402 mutation of E. coli. A second genomic region of 12.8 kb complemented entD, entC147, entE405, and entA403 mutations of E. coli. Although functions encoded by catechol biosynthesis genes (cbsA, cbsB, cbsC, cbsD, and cbsE) of E. carotovora were interchangeable with those encoded by corresponding enterobactin biosynthesis genes (entA, entB, entC, entD, and entE), only cbsE hybridized to its functional counterpart (entE) in E. coli. The cbsEA region of E. carotovora W3C105 hybridized to genomic DNA of 21 diverse strains of E. carotovora but did not hybridize to that of a chrysobactin-producing strain of Erwinia chrysanthemi. Strains of E. carotovora fell into nine groups on the basis of sizes of restriction fragments that hybridized to the cbsEA region, indicating that catechol biosynthesis genes were highly polymorphic among strains of E. carotovora.

Bull, Carolee T.; Ishimaru, Carol A.; Loper, Joyce E.

1994-01-01

246

Plasma Metanephrines Are Markers of Pheochromocytoma Produced by Catechol-O- Methyltransferase Within Tumors  

Microsoft Academic Search

This study examined whether the high sensitivity of plasma free metanephrines for diagnosis of pheochromocytoma may result from production of free metanephrines within tumors. Presence in pheo- chromocytomas of catechol-O-methyltransferase (COMT), the en- zyme responsible for conversion of catecholamines to metanephrines, was confirmed by Western blot analysis, enzyme assay, and immu- nohistochemistry. Western blot analysis and enzyme assay indicated that

GRAEME EISENHOFER; HARRY KEISER; PETER FRIBERG; EVA MEZEY; THANH-TRUC HUYNH; BHARGAVA HIREMAGALUR; TODD ELLINGSON; SUSHIL DUDDEMPUDI; AGNES EIJSBOUTS; JACQUES W. M. LENDERS

247

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

248

Role of catecholate siderophores in gram-negative bacterial colonization of the mouse gut.  

PubMed

We investigated the importance of the production of catecholate siderophores, and the utilization of their iron (III) complexes, to colonization of the mouse intestinal tract by Escherichia coli. First, a ?tonB strain was completely unable to colonize mice. Next, we compared wild type E. coli MG1655 to its derivatives carrying site-directed mutations of genes for enterobactin synthesis (?entA::Cm; strain CAT0), ferric catecholate transport (?fiu, ?fepA, ?cir, ?fecA::Cm; CAT4), or both (?fiu, ?fepA, ?fecA, ?cir, ?entA::Cm; CAT40) during colonization of the mouse gut. Competitions between wild type and mutant strains over a 2-week period in vivo showed impairment of all the genetically engineered bacteria relative to MG1655. CAT0, CAT4 and CAT40 colonized mice 10(1)-, 10(5)-, and 10(2)-fold less efficiently, respectively, than MG1655. Unexpectedly, the additional inability of CAT40 to synthesize enterobactin resulted in a 1000-fold better colonization efficiency relative to CAT4. Analyses of gut mucus showed that CAT4 hyperexcreted enterobactin in vivo, effectively rendering the catecholate transport-deficient strain iron-starved. The results demonstrate that, contrary to prior reports, iron acquisition via catecholate siderophores plays a fundamental role in bacterial colonization of the murine intestinal tract. PMID:23209633

Pi, Hualiang; Jones, Shari A; Mercer, Lynn E; Meador, Jessica P; Caughron, Joyce E; Jordan, Lorne; Newton, Salete M; Conway, Tyrrell; Klebba, Phillip E

2012-11-29

249

Effects of 4-Tertiary Butyl Catechol on Glutathione-Metabolizing Enzymes In vivo and In vitro.  

National Technical Information Service (NTIS)

The effects of noncytotoxic doses of 4-tertiary-butyl-catechol (98293) (TBC) on glutathione-S-transferase (GST) activity in the skin of male, 2-month-old Uscd-mice and B16-murine-melanoma cells in culture were investigated. These effects were studied in r...

G. A. Gellin K. Fukuyama K. Yonemoto T. Kawashima W. L. Epstein

1988-01-01

250

Cyclopiazonic acid biosynthesis of Aspergillus flavus and Aspergillus oryzae.  

PubMed

Cyclopiazonic acid (CPA) is an indole-tetramic acid neurotoxin produced by some of the same strains of A. flavus that produce aflatoxins and by some Aspergillus oryzae strains. Despite its discovery 40 years ago, few reviews of its toxicity and biosynthesis have been reported. This review examines what is currently known about the toxicity of CPA to animals and humans, both by itself or in combination with other mycotoxins. The review also discusses CPA biosynthesis and the genetic diversity of CPA production in A. flavus/oryzae populations. PMID:22069533

Chang, Perng-Kuang; Ehrlich, Kenneth C; Fujii, Isao

2009-11-06

251

Polyaniline-iron oxide nanohybrid film as multi-functional label-free electrochemical and biomagnetic sensor for catechol.  

PubMed

Polyaniline-iron oxide magnetic nanohybrid was synthesized and characterized using various spectroscopic, microstructural and electrochemical techniques. The smart integration of Fe3O4 nanoparticles within the polyaniline (PANI) matrix yielded a mesoporous nanohybrid (Fe3O4@PANI) with high surface area (94m(2)g(-1)) and average pore width of 12.8nm. Catechol is quasi-reversibly oxidized to o-quinone and reduced at the Fe3O4@PANI modified electrodes. The amperometric current response toward catechol was evaluated using the nanohybrid and the sensitivity and detection limit were found to be 312?A?L(-1) and 0.2nM, respectively. The results from electrochemical impedance spectroscopy (EIS) indicated that the increased solution resistance (Rs) was due to elevated adsorption of catechol on the modified electrodes. Photoluminescence spectra showed ligand-to-metal charge transfer (LMCT) between p-? orbitals of the phenolate oxygen in catechol and the d-?* metal orbital of Fe3O4@PANI nanohybrid. Potential dependent spectroelectrochemical behavior of Fe3O4@PANI nanohybrid toward catechol was studied using UV/vis/NIR spectroscopy. The binding activity of the biomagnetic particles to catechol through Brownian relaxation was evident from AC susceptibility measurements. The proposed sensor was used for successful recovery of catechol in tap water samples. PMID:23998532

Chandra, Sudeshna; Lang, Heinrich; Bahadur, Dhirendra

2013-07-31

252

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

253

Bioactive steroids from Oryza sativa L.  

PubMed

Rice is one of the most interesting crops in the world from both the social and the economic point of views. The monoculture practices along with the heavy use of herbicides are characteristic of modern agriculture and are inducing the appearance of tolerant and/or herbicide resistant weed biotypes. This is the case the world's main weed of rice barnyardgrass (Echinochloa crus-galli). Alternative strategies for weed suppression consist of the use of chemicals from rice due to necessity of obtaining new herbicides with new modes of action that could prevent resistance phenomena. In order to carry out a study that guides to the isolation of the most active compounds from rice, different extracts were achieved, and their activities evaluated. So, all the plant material was divided into three parts: fresh plant, dried plant, and fresh plant from Pluviotron. The aerial part was separated from roots in all cases and extracted in water, in organic solvents as well as with the Pluviotron device. The activity of the 12 extracts obtained was evaluated using a generalist bioassay, wheat etiolated coleoptiles bioassay, and a phytotoxic bioassay on barnyardgrass as target species. The bioactive extracts were fractionated and 15 compounds were isolated and identified by spectroscopic methods. Eight of these compounds were isolated for the first time in Oryza sativa. The most phytotoxic compounds on E. crus-galli were ergosterol peroxide and 7-oxo-stigmasterol. In the case of ergosterol peroxide the activity was higher than the commercial herbicide Logran. This is the first report of potential allelopathic activity of steroids on weeds based on their phytotoxicity. PMID:16620896

Macías, Francisco A; Chinchilla, Nuria; Varela, Rosa M; Molinillo, José M G

2006-04-18

254

Induced adaptive and cross-protection responses against oxidative stress killing in a bacterial phytopathogen, Xanthomonas oryzae pv. oryzae  

Microsoft Academic Search

In Xanthomonas oryzae pv. oryzae, exposure to a sub-lethal concentration of H2O2 conferred protection to subsequent challenges with a killing concentration of H2O2 (30 mM, adaptive response). No adaptive response to tert-butylhydroperoxides (tBOOH) or the superoxide generator menadione was observed. However, exposure to sub-lethal concentrations of tBOOH or N-ethylmaleimide (a thiol reagent) induced cross-protection to low 30 mM lethal levels

Skorn Mongkolsuk; Paiboon Vattanaviboon; Wipa Praituan

1997-01-01

255

Lysobacter oryzae sp. nov., isolated from the rhizosphere of rice (Oryza sativa L.).  

PubMed

The taxonomic position of a novel bacterial strain, YC6269(T), isolated from the rhizosphere of rice (Oryza sativa L.) managed under no-tillage practice in Jinju, South Korea, was studied using polyphasic approach. Cells of the strain were Gram-negative, rod-shaped and facultatively anaerobic. The novel strain grew at a temperature of 15-42 degrees C (optimum at 28 degrees C). Growth of the strain occurred between pH 5.5 and 11.0, with an optimum at pH 7.0-8.0. The G+C content of the total DNA was 67.4 mol%. The 16S rRNA gene sequence of the strain was most closely related to species of the genus Lysobacter, Lysobacter yangpyeongensis DSM 17635(T) (98.6 %), Lysobacter niabensis GH34-4(T) (97.2 %), Lysobacter enzymogenes DSM 2043(T) (96.9 %), Lysobacter daejeonensis DSM 17634(T) (96.3 %) and Lysobacter niastensis GH41-7(T) (96.2 %). The novel strain showed <96.0 % similarity with other species of the genus Lysobacter. Chemotaxonomic data (major quinone, Q-8; major polar lipids, phosphatidylethanolamine, phosphatidylglycerol and phosphatidyl-N-methylethanolamine, and major fatty acids, C(15 : 0) iso, C(16 : 0) iso, C(17 : 0) iso and C(17 : 1) iso omega9c) supported the affiliation of strain YC6269(T) to the genus Lysobacter. Phylogenetic analysis based on the 16S rRNA gene sequences, DNA-DNA hybridization data and biochemical and physiological characteristics strongly supported the genotypic and phenotypic differentiation of strain YC6269(T) from recognized species of the genus Lysobacter. Strain YC6269(T), therefore, represents a novel member of the genus Lysobacter, for which the name Lysobacter oryzae sp. nov. is proposed. The type strain is YC6269(T) (=KCTC 22249(T)=DSM 21044(T)). PMID:19329586

Aslam, Zubair; Yasir, Muhammad; Jeon, Che Ok; Chung, Young Ryun

2009-04-01

256

Identification of Genes Required for Nonhost Resistance to Xanthomonas oryzae pv. oryzae Reveals Novel Signaling Components  

PubMed Central

Background Nonhost resistance is a generalized, durable, broad-spectrum resistance exhibited by plant species to a wide variety of microbial pathogens. Although nonhost resistance is an attractive breeding strategy, the molecular basis of this form of resistance remains unclear for many plant-microbe pathosystems, including interactions with the bacterial pathogen of rice, Xanthomonas oryzae pv. oryzae (Xoo). Methods and Findings Virus-induced gene silencing (VIGS) and an assay to detect the hypersensitive response (HR) were used to screen for genes required for nonhost resistance to Xoo in N. benthamiana. When infiltrated with Xoo strain YN-1, N. benthamiana plants exhibited a strong necrosis within 24 h and produced a large amount of H2O2 in the infiltrated area. Expression of HR- and defense-related genes was induced, whereas bacterial numbers dramatically decreased during necrosis. VIGS of 45 ACE (Avr/Cf-elicited) genes revealed identified seven genes required for nonhost resistance to Xoo in N. benthamiana. The seven genes encoded a calreticulin protein (ACE35), an ERF transcriptional factor (ACE43), a novel Solanaceous protein (ACE80), a hydrolase (ACE117), a peroxidase (ACE175) and two proteins with unknown function (ACE95 and ACE112). The results indicate that oxidative burst and calcium-dependent signaling pathways play an important role in nonhost resistance to Xoo. VIGS analysis further revealed that ACE35, ACE80, ACE95 and ACE175, but not the other three ACE genes, interfered with the Cf-4/Avr4-dependent HR. Conclusions/Significance N. benthamiana plants inoculated with Xoo respond by rapidly eliciting an HR and nonhost resistance. The oxidative burst and other signaling pathways are pivotal in Xoo-N. benthamiana nonhost resistance, and genes involved in this response partially overlap with those involved in Cf/Avr4-dependent HR. The seven genes required for N. benthamiana-mediated resistance to Xoo provide a basis for further dissecting the molecular mechanism of nonhost resistance.

Li, Wen; Xu, You-Ping; Zhang, Zhi-Xin; Cao, Wen-Yuan; Li, Fei; Zhou, Xueping; Chen, Gong-You; Cai, Xin-Zhong

2012-01-01

257

In-depth analysis of the Magnaporthe oryzae conidial proteome.  

PubMed

The filamentous fungus Magnaporthe oryzae (M. oryzae) is the causative agent of rice blast disease and presents a significant threat to worldwide rice production. To establish the groundwork for future research on the pathogenic development of M. oryzae, a global proteomic study of conidia was performed. The filter aided sample preparation method (FASP) and anion StageTip fractionation combined with long, optimized shallow 210 min nanoLC gradients prior to mass spectrometry analysis on an Orbitrap XL was applied, which resulted in a doubling of protein identifications in comparison to our previous GeLC analysis. Herein, we report the identification of 2912 conidial proteins at a 1% protein false discovery rate (FDR) and we present the most extensive study performed on M. oryzae conidia to date. A similar distribution between identified proteins and the predicted proteome was observed when subcellular localization analysis was performed, suggesting the detected proteins build a representative portion of the predicted proteome. A higher percentage of cytoplasmic proteins (associated with translation, energy, and metabolism) were observed in the conidial proteome relative to the whole predicted proteome. Conversely, nuclear and extracellular proteins were less well represented in the conidial proteome. Further analysis by gene ontology revealed biological insights into identified proteins important for central metabolic processes and the physiology of conidia. PMID:23039028

Gokce, Emine; Franck, William L; Oh, Yeonyee; Dean, Ralph A; Muddiman, David C

2012-10-29

258

Whole genome comparison of Aspergillus flavus and A. oryzae  

Microsoft Academic Search

Aspergillus flavus is a plant and animal pathogen that also produces the potent carcinogen aflatoxin. Aspergillus oryzae is a closely related species that has been used for centuries in the food fermentation industry and is Generally Regarded As Safe (GRAS). Whole genome sequences for these two fungi are now complete, providing us with the opportunity to examine any genomic differences

G. A. PAYNE; W. C. NIERMAN; Jennifer R. Wortman; B. L. PRITCHARD; D. BROWN; R. A. DEAN; D BHATNAGAR; T. E. CLEVELAND; MASAYUKI MACHIDA; J. YU

2006-01-01

259

Aspergillus oryzae as Probiotic in Poultry - A Review  

Microsoft Academic Search

Probiotics are widely accepted as an alternative to in-feed antibiotics in poultry production. So far, the frequently used microorganisms in probiotics are strains of lactic acid producing bacteria having specificity of adhering to the intestinal epithelium. Recently, a probiotic containing novel strain such as Aspergillus oryzae is also in practice, but its effect on performance of poultry is limited. The

2006-01-01

260

Sensory acceptability evaluation of irradiated rice, oryza sativa indica.  

National Technical Information Service (NTIS)

The non-glutinous and glutinous types of polished rice, Oryza sativa indica were subjected to gamma rays at ambient temperature and stored at 27+-1(sup 0)C for one week. The irradiated rice was cooked and tasted by members of trained panel. Using Hedonic ...

S. Loaharanu M. Sutantawong A. Ungsunanatawiwat

1971-01-01

261

RNA silencing of lactate dehydrogenase gene in Rhizopus oryzae  

PubMed Central

Rhizopus oryzae is a filamentous fungus, belonging to the order Mucorales. It can ferment a wide range of carbohydrates hydrolyzed from lignocellulosic materials and even cellobiose to produce ethanol. However, R. oryzae also produces lactic acid as a major metabolite, which reduces the yield of ethanol. In this study, we show that significant reduction of lactic acid production could be achieved by short (25nt) synthetic siRNAs targeting the ldhA gene. The average yield of lactic acid production by R. oryzae during the batch fermentation process, where glucose had been used as a sole carbon source, diminished from 0.07gm/gm in wild type to 0.01gm/gm in silenced samples. In contrast, the average yield of ethanol production increased from 0.39gm/gm in wild type to 0.45gm/gm in silenced samples. These results show 85.7% (gm/gm) reduction in lactic acid production as compared with the wild type R. oryzae, while an increase of 15.4% (gm/gm) in ethanol yield.

Gheinani, Ali Hashemi; Jahromi, Neda Haghayegh; Feuk-Lagerstedt, Elisabeth; Taherzadeh, Mohammad J

2011-01-01

262

WHOLE GENOME COMPARISON OF ASPERGILLUS FLAVUS AND A. ORYZAE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aspergillus flavus is a plant and animal pathogen that also produces the potent carcinogen aflatoxin. Aspergillus oryzae is a closely related species that has been used for centuries in the food fermentation industry and is generally regarded as safe (GRAS). Whole genome sequences for these two fu...

263

NADPH oxidases and cardiac remodelling  

Microsoft Academic Search

A heart under chronic stress undergoes cardiac remodelling, a process that comprises structural and functional changes including\\u000a cardiomyocyte hypertrophy, interstitial fibrosis, contractile dysfunction, cell death and ventricular dilatation. Reactive\\u000a oxygen species (ROS)-dependent modulation of intracellular signalling is implicated in the development of cardiac remodelling.\\u000a Among the different ROS sources that are present in the heart, NADPH oxidases (NOXs) are particularly

Adam Nabeebaccus; Min Zhang; Ajay M. Shah

2011-01-01

264

Cholesterol Oxidase: Structure and Function  

Microsoft Academic Search

\\u000a Cholesterol oxidase is a bacterial-specific flavoenzyme that catalyzes the oxidation and isomerisation of steroids containing\\u000a a 3? hydroxyl group and a double bond at the ?5–6 of the steroid ring system. The enzyme is a member of a large family of\\u000a flavin-specific oxidoreductases and is found in two different forms: one where the flavin adenine dinucleotide (FAD) cofactor\\u000a is covalently

Alice Vrielink

265

Isolation and Expression of Lactate Dehydrogenase Genes from Rhizopus oryzae  

PubMed Central

Rhizopus oryzae is used for industrial production of lactic acid, yet little is known about the genetics of this fungus. In this study I cloned two genes, ldhA and ldhB, which code for NAD+-dependent l-lactate dehydrogenases (LDH) (EC 1.1.1.27), from a lactic acid-producing strain of R. oryzae. These genes are similar to each other and exhibit more than 90% nucleotide sequence identity and they contain no introns. This is the first description of ldh genes in a fungus, and sequence comparisons revealed that these genes are distinct from previously isolated prokaryotic and eukaryotic ldh genes. Protein sequencing of the LDH isolated from R. oryzae during lactic acid production confirmed that ldhA codes for a 36-kDa protein that converts pyruvate to lactate. Production of LdhA was greatest when glucose was the carbon source, followed by xylose and trehalose; all of these sugars could be fermented to lactic acid. Transcripts from ldhB were not detected when R. oryzae was grown on any of these sugars but were present when R. oryzae was grown on glycerol, ethanol, and lactate. I hypothesize that ldhB encodes a second NAD+-dependent LDH that is capable of converting l-lactate to pyruvate and is produced by cultures grown on these nonfermentable substrates. Both ldhA and ldhB restored fermentative growth to Escherichia coli (ldhA pfl) mutants so that they grew anaerobically and produced lactic acid.

Skory, Christopher D.

2000-01-01

266

Polyphenol oxidase and herbivore defense in trembling aspen (Populus tremuloides): cDNA cloning, expression, and potential substrates.  

PubMed

The biochemical anti-herbivore defense of trembling aspen (Populus tremuloides Michx.) was investigated in a molecular analysis of polyphenol oxidase (PPO; EC 1.10.3.2). A PPO cDNA was isolated from a trembling aspen wounded leaf cDNA library and its nucleotide sequence determined. Southern analysis indicated the presence of two PPO genes in the trembling aspen genome. Expression of PPO was found to be induced after herbivory by forest tent caterpillar, by wounding, and by methyl jasmonate treatment. Wound induction was systemic, and occurred in unwounded leaves on wounded plants. This pattern of expression is consistent with a role of this enzyme in insect defense. A search for potential PPO substrates in ethanolic aspen leaf extracts using electron spin resonance (ESR) found no pre-existing diphenolic compounds. However, following a brief delay and several additions of oxygen, an ESR signal specific for catechol was detected. The source of this catechol was most likely the aspen phenolic glycosides tremulacin or salicortin which decomposed during ESR experiments. This was subsequently confirmed in experiments using pure salicortin. PMID:11473716

Haruta, Miyoshi; Pedersen, Jens A.; Constabel, C. Peter

2001-08-01

267

The Effect of Monoamine Oxidase and Diamine Oxidase Inhibitors on Norepinephrine and Histamine in Rat Heart.  

National Technical Information Service (NTIS)

The effect of several hydrazine and nonhydrazine compounds on the concentrations of norepinephrine and histamine in the rat heart was studied. The compounds used were either monoamine oxidase (MAO) or diamine oxidase (DAO) inhibitors. Hydrazine (0.31 mmol...

D. H. Ross M. A. Medina

1969-01-01

268

Electron Redistribution in Mixed Valence Cytochrome Oxidase Following Photolysis of Carboxy-Oxidase,  

National Technical Information Service (NTIS)

The transport of electrons in the oxidase is frequently viewed as unidirectional except when energy-dependent reverse electron transport occurs. In this communication, electron redistribution between redox centers in nonliganded mixed valence oxidase will...

H. J. Harmon

1988-01-01

269

Monoamine oxidase in adult Hymenolepis diminuta (Cestoda).  

PubMed

A membrane-bound monoamine oxidase (EC 1.4.3.4) was demonstrated in homogenates of Hymenolepis diminuta. The enzyme oxidized a variety of biologically active amines (in decreasing order: dopamine, adrenaline, noradrenaline, tryptamine, tyramine, octopamine), there was, however, no activity with 5-hydroxytryptamine or benzylamine. No diamine oxidase (EC 1.4.3.6.) could be detected in H. diminuta (using histamine, cadaverine or putrescine as substrates). The monoamine oxidase from H. diminuta was not inhibited by azide, hydroxylamine or semicarbazide, but was inhibited by cupferron, alpha-alpha dipyridyl and iodoacetamide, and by the specific monoamine oxidase inhibitors pargyline, nialamide and iproniazid. Several anthelmintics were also found to be inhibitors of monoamine oxidase. The possible roles of monoamine oxidase in H. diminuta are discussed. PMID:419001

Moreno, M S; Barrett, J

1979-02-01

270

Evaluating the effects of cold water diffusates against Xanthomonas oryzae Pv. Oryzae causing bacterial leaf blight (BLB) in rice  

Microsoft Academic Search

The crude extracts of 63 plants were used for testing antibacterial activity against Xanthmonas oryazae Pv. oryzae that causes bacterial leaf blight (BLB) in rice plants. Only ten aqueous extracts of botanicals (Thuja orientalis, Prunus domestica, Citrus limon, Allium sativum, Vitis vinefera, Mangifera indica, Phyllanthus emblica, and Terminalia chebula) showed maximum activity against Xanthmonas oryazae in a plate agar diffusion

Rukhsana Jabeen; Muhammad Ashraf; Iftikhar Ahmad

2009-01-01

271

Controlled synthesis of PEI-coated gold nanoparticles using reductive catechol chemistry for siRNA delivery  

Microsoft Academic Search

Development of nano-sized gene delivery vehicles for small interfering RNA (siRNA) delivery is of great importance for their clinical applications such as cancer therapy. Herein, we demonstrate the controlled synthesis of polyethyleneimine (PEI)-coated gold nanoparticles (AuNPs) using catechol-conjugated PEI (PEI-C) for siRNA delivery. Since the conjugated catechol groups are reductive and moderately hydrophobic, PEI-C formed spherical multi-cored micelles in aqueous

Yuhan Lee; Soo Hyeon Lee; Jee Seon Kim; Atsushi Maruyama; Xuesi Chen; Tae Gwan Park

2011-01-01

272

NADPH oxidase(s): new source(s) of reactive oxygen species in the vascular system?  

Microsoft Academic Search

Reactive oxygen species play an important role in a variety of (patho)physiological vascular processes. Recent publications have produced evidence of a role for putative non-phagocyte NADP oxidase(s) in the vascular production of reactive oxygen species. In the present review, we discuss the detection of the different components of NADP oxidase(s) in the vascular system, together with the putative role of

L Van Heerebeek; C. Meischl; W. Stooker; C. J. L. M. Meijer; H. W. M. Niessen; D. Roos

2002-01-01

273

Optical fiber spectroelectrochemical device for detection of catechol at press-transferred single-walled carbon nanotubes electrodes.  

PubMed

A new long-optical-pathway spectroelectrochemical cell for absorptometric measurements in the UV-Vis region was developed. This cell consists of two optical fibers brought face to face and fixed on the working electrode support. As a proof of concept, the spectroelectrochemical cell was applied to the determination of catechol using a press-transferred single-walled carbon nanotube film as the working electrode. Voltabsorptometry was demonstrated to be very helpful in understanding the mechanism of catechol oxidation. The experiments showed that the main oxidation product is o-benzoquinone, but other soluble side products are also observed. Multivariate calibration explains the selection of 390 nm as the best wavelength for the univariate absorptometric determination of catechol, avoiding the interference of oxidation side products. Catechol was quantified using both the electrochemical and the spectroscopic signal, demonstrating that this hybrid technique is an autovalidated analytical method. Dual detection of catechol was also carried out using amperometric spectroelectrochemistry. Finally, spectroelectrochemistry was used to quantify catechol in the presence of hydroquinone. PMID:23407809

Garoz-Ruiz, Jesus; Izquierdo, Daniel; Colina, Alvaro; Palmero, Susana; Heras, Aranzazu

2013-02-14

274

Evolution of CO{sub 2} during birnessite-induced oxidation of {sup 14}C-labeled catechol  

SciTech Connect

Phenolic compounds undergo several transformation processes in soil and water (i.e., partial degradation, mineralization, and polymerization), many of which have been attributed primarily to biological activity. Results from previous work indicate that naturally occurring Mn oxides are also capable of oxidizing phenolic compounds. In the present study, {sup 14}C-labeled catechol was reacted with birnessite (manganese oxide) in aqueous suspension of pH 4. The mass of catechol-derived c in solid, solution, and gas phases was quantified as a function of time. Between 5 and 16% of the total catechol C was liberated as CO{sub 2} from oxidation and abiotic ring cleavage under various conditions. Most of the {sup 14}C (55--83%) was incorporated into the solid phase in the form of stable organic reaction products whereas solution phase {sup 14}C concentrations increased from 16 to 39% with a doubling of total catechol added. Polymerization and CO{sub 2} evolution appear to be competitive pathways in the transformation of catechol since their relative importance was strongly dependent on initial birnessite-catechol reaction conditions. Solid phase Fourier transform infrared (FTIR) spectra are consistent with the presence of phenolic, quinone, and aromatic ring cleavage products. Carbon dioxide release appears to be limited by availability of reactive birnessite surface sites and it is diminished in the presence of polymerized reaction products.

Majcher, E.H.; Chorover, J.; Bollag, J.M.; Huang, P.M.

2000-02-01

275

21 CFR 866.2420 - Oxidase screening test for gonorrhea.  

Code of Federal Regulations, 2010 CFR

...articles intended to identify by chemical reaction, cytochrome oxidase, an oxidizing enzyme that is associated...containing an ingredient that will react with cytochrome oxidase. When cytochrome oxidase is present, the swab turns a...

2010-04-01

276

21 CFR 866.2420 - Oxidase screening test for gonorrhea.  

Code of Federal Regulations, 2010 CFR

...articles intended to identify by chemical reaction, cytochrome oxidase, an oxidizing enzyme that is associated...containing an ingredient that will react with cytochrome oxidase. When cytochrome oxidase is present, the swab turns a...

2009-04-01

277

New Hybrid Properties of TiO2 Nanoparticles Surface Modified With Catecholate Type Ligands  

NASA Astrophysics Data System (ADS)

Surface modification of nanocrystalline TiO2 particles (45 Ĺ) with bidentate benzene derivatives (catechol, pyrogallol, and gallic acid) was found to alter optical properties of nanoparticles. The formation of the inner-sphere charge-transfer complexes results in a red shift of the semiconductor absorption compared to unmodified nanocrystallites. The binding structures were investigated by using FTIR spectroscopy. The investigated ligands have the optimal geometry for chelating surface Ti atoms, resulting in ring coordination complexes (catecholate type of binuclear bidentate binding-bridging) thus restoring in six-coordinated octahedral geometry of surface Ti atoms. From the Benesi-Hildebrand plot, the stability constants at pH 2 of the order 103 M-1 have been determined.

Jankovi?, Ivana A.; Šaponji?, Zoran V.; Džunuzovi?, Enis S.; Nedeljkovi?, Jovan M.

2010-01-01

278

pH- and voltage-responsive chitosan hydrogel through covalent cross-linking with catechol.  

PubMed

A new method for covalently cross-linking chitosan is developed by chemically oxidizing catechol to o-quinone which subsequently reacts with and cross-links chitosan through Michael addition and Schiff base formation. The cross-linked chitosan film shows a pH-responsive, switchlike behavior toward the negatively charged redox probe, Fe(CN)(6)(3-/4-), and withstands harsh acidic conditions. The negative Fe(CN)(6)(3-/4-) is found to be trapped and enriched in the catechol-cross-linked chitosan film under acidic conditions and released into solution by either increasing pH or applying a negative voltage. Chitosan films made with different techniques, i.e., solvent evaporation (simple deposition), electrodeposition, and covalent cross-linking, are examined using cyclic voltammetry and electrochemical impedance spectroscopy (EIS), and the results demonstrate that fabrication methods greatly affect the properties of the chitosan films. PMID:22229705

Zhang, Yongchao; Thomas, Yanique; Kim, Eunkyoung; Payne, Gregory F

2012-01-24

279

Pharmacogenetics of catechol-O-methyltransferase: frequency of low activity allele in a Ghanaian population.  

PubMed

Catechol-O-methyltransferase (COMT) catalyses the O-methylation of neurotransmitters, catechol hormones and drugs such as levodopa and methyldopa. Ethnic differences in COMT activity have been observed in several populations. Previous studies suggest that the g1947G>A low activity allele is less common in individuals of African origin. COMT genotyping was performed using a mini-sequencing method in 195 healthy Ghanaians with a frequency of the homozygous g1947G>A of 6%. This study provides confirmation that the low activity COMT allele is less common in individuals of African origin. This finding may be important clinically with regards to the treatment of many neuropsychiatric disorders and in the pathophysiology of various human disorders including estrogen-induced cancers, Parkinson's disease, depression and hypertension. PMID:11058906

Ameyaw, M M; Syvänen, A C; Ulmanen, I; Ofori-Adjei, D; McLeod, H L

2000-11-01

280

New Hybrid Properties of TiO2 Nanoparticles Surface Modified With Catecholate Type Ligands  

PubMed Central

Surface modification of nanocrystalline TiO2 particles (45 Ĺ) with bidentate benzene derivatives (catechol, pyrogallol, and gallic acid) was found to alter optical properties of nanoparticles. The formation of the inner-sphere charge–transfer complexes results in a red shift of the semiconductor absorption compared to unmodified nanocrystallites. The binding structures were investigated by using FTIR spectroscopy. The investigated ligands have the optimal geometry for chelating surface Ti atoms, resulting in ring coordination complexes (catecholate type of binuclear bidentate binding–bridging) thus restoring in six-coordinated octahedral geometry of surface Ti atoms. From the Benesi–Hildebrand plot, the stability constants at pH 2 of the order 103 M?1 have been determined.

2010-01-01

281

Doubly biomimetic catecholic phosphorylcholine copolymer: a platform strategy for fabricating antifouling surfaces.  

PubMed

A doubly biomimetic PMNC polymer bearing cell antifouling phosphorylcholine and mussel adhesive protein catechol groups is synthesized. The polymer can be deposited onto a variety of substrates by dip-coating in an aqueous solution, adhering to surfaces via the catechol functional group while at the same time forming a cell outer membrane mimetic antifouling surface. Contact angle, ATR-FTIR and XPS measurements confirm polymer coating formation on a variety of inorganic and organic substrates. BSA and bovine plasma fibrinogen protein adsorption on PMNC coated surfaces are reduced significantly compared to unmodified substrates, and platelet adhesion from human serum onto the PMNC coated substrate surfaces is highly suppressed in this study. PMID:22610777

Gong, Yong-Kuan; Liu, Li-Ping; Messersmith, Phillip B

2012-05-18

282

Sugar oxidoreductases and veratryl alcohol oxidase as related to lignin degradation  

Microsoft Academic Search

Properties of cellobiose:quinone oxidoreductase (CBQ), cellobiose dehydrogenase (CDH), glyoxal oxidase (GLOX), glucose oxidases and veratryl alcohol oxidase (VAO) are reviewed. There is strong evidence that CDH reduces quinones, phenoxy and cation radicals. Glucose oxidases (glucose 1-oxidase and pyranose 2-oxidase) and VAO have been less investigated but evidence for reduction of the above compounds is accumulating. Pyranose oxidase, glyoxal oxidase and

Paul Ander; Liberato Marzullo

1997-01-01

283

Whole genomic sequencing of RT98 mitochondria derived from Oryza rufipogon and northern blot analysis to uncover a cytoplasmic male sterility-associated gene.  

PubMed

Cytoplasmic male sterility (CMS) is a maternally inherited trait resulting in the failure to produce functional pollen and is often observed when an alien cytoplasm is transferred into a cultivated species. An RT98A CMS line and an RT98C fertility restorer line were obtained by successive backcrossing between Oryza rufipogon W1109 and Oryza sativa cultivar Taichung 65. To uncover the CMS-associated mitochondrial genes, we determined the complete sequence of the RT98-CMS mitochondrial genome using next-generation pyrosequencing, and searched new open reading frames (orfs) absent in a reported mitochondrial genome of O. sativa Nipponbare. Then, six candidates were selected for the CMS-associated genes based on the criteria in which they were chimeric in structure or encoded a peptide with transmembrane domains. One of the candidates, orf113, showed different transcript sizes between RT98A and RT98C on Northern blot analysis. The orf113 gene was shown to be co-transcribed with atp4 and cox3 encoding ATP synthase F0 subunit 4 and Cyt c oxidase subunit 3, respectively, and their transcripts were distinctly processed in the presence of a fertility restorer gene. Our results indicate that orf113 is a CMS-associated gene of RT98-CMS. PMID:23248202

Igarashi, Keisuke; Kazama, Tomohiko; Motomura, Keiji; Toriyama, Kinya

2012-12-17

284

Breast Cancer Risk Reduction and Membrane-Bound Catechol O-Methyltransferase Genetic Polymorphisms  

Microsoft Academic Search

Catechol O-methyltransferase (COMT)-catalyzed methylation of catecholestrogens has been proposed to play a protective role in estrogen-induced genotoxic carcinogenesis. We have taken a comprehensive approach to test the hypothesis that genetic variation in COMT might influence breast cancer risk. Fifteen COMT single nucleotide polymorphisms (SNPs) select- ed on the basis of in-depth resequencing of the COMT gene were genotyped in 1,482

Yuan Ji; Janet Olson; Jianping Zhang; Michelle Hildebrandt; Liewei Wang; James Ingle; William Miller; J. Michael Dixon; Hiltrud Brauch; Michel Eichelbaum; Christina Justenhoven; Ute Hamann; Thomas Bruning; Shan Wang-Gohrke; Daniel Schaid; Richard Weinshilboum; H. Lee Moffitt

285

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

286

Polycyclic aromatic hydrocarbons from the co-pyrolysis of catechol and 1,3-butadiene  

Microsoft Academic Search

In order to better understand the reactions responsible for the formation and growth of polycyclic aromatic hydrocarbons (PAH) from solid fuels, we have performed pyrolysis experiments in an isothermal laminar-flow reactor (at temperatures of 600–1000°C and a fixed residence time of 0.3s) with catechol, a model fuel representative of the aromatic moieties in coal and biomass fuels; 1,3-butadiene, a major

Shiju Thomas; Mary J. Wornat

2009-01-01

287

Selective alkylation of catechol with t-butyl alcohol over HY and modified HY zeolites  

Microsoft Academic Search

Vapor phase alkylation of catechol with t-butyl alcohol (TBA) has been studied over HY and dealuminated HY zeolites (obtained by controlled steaming) in the temperature range 120–200 °C. The predominantly formed product over these catalysts is 4-t-butylcatechol (4-TBC) with more than 86% selectivity, the minor products being 3-t-butylcatechol (3-TBC) and 3,5-di-t-butylcatechol (3,5-DTBC). Moderately steam-treated HY zeolites (steamed at 550 and

R. Anand; R. Maheswari; K. U. Gore; V. R. Chumbhale

2002-01-01

288

Temperature-controlled release of catechol dye in thermosensitive phenylboronate-containing copolymers: A quantitative study  

Microsoft Academic Search

The reversible complex formation between two phenylboronic acid bearing copolymers and the catechol dye Alizarin Red S (ARS) was studied by dialysis experiments coupled with UV–visible spectroscopy. The first copolymer based on N-isopropylacrylamide (NIPAM) is thermosensitive, whereas the second one based on N,N-dimethylacrylamide (DMAM) is not. The investigation resulted in the quantitative determination of the host–guest binding constants at two

Gaëlle Carré de Lusançay; Sophie Norvez; Ilias Iliopoulos

2010-01-01

289

Association of Eating Disorders with Catechol-O-Methyltransferase Gene Functional Polymorphism  

Microsoft Academic Search

Aim: The aim of this study was to evaluate functional catechol-O-methyltransferase (COMT) genetic variation as a risk factor for eating disorders (ED). Method: Eighty women receiving treatment for serious ED (52 for anorexia nervosa, 28 for bulimia nervosa) and 116 age-matched females in the control group underwent COMT genotyping for polymorphism in exon 4 (codon 158). Both the low-activity allele

Anna Grzywacz; Jerzy Samochowiec

2006-01-01

290

Catalytic cracking of catechols and hydroquinones in the presence of nano-particle iron oxide  

Microsoft Academic Search

Nano-particle “iron oxide” was found to be an effective catalyst for the pyrolytic conversion of phenolic and other environmentally harmful aromatic compounds evolved during the combustion and pyrolysis of biomass. Catalytic cracking and oxidation of catechol, 3-methylcatechol, hydroquinone, 2-methylhydroquinone, and 2,3-dimethylhydroquinone over the temperature range of 180–430°C and under partially oxidative conditions were studied using nano-particle “iron oxide”. We employed

Eun-Jae Shin; Donald E. Miser; W. Geoffrey Chan; Mohammad R. Hajaligol

2005-01-01

291

Catechol derivatives and anion adsorption onto alumina surfaces in aqueous media: influence on the electrokinetic properties  

Microsoft Academic Search

A high state of dispersion of alumina particles can be achieved by using molecules derived from Catechol 1,2(OH)2C6H4, such as Tiron (OH)2C6H2(SO3Na)2 which allows to obtain stable alumina suspensions. In the field of understanding the dispersion mechanism of Tiron and the contribution of each functional group grafted onto the benzene ring of the Tiron molecule, adsorption experiments and surface charge

R Laucournet; C Pagnoux; T Chartier; J. F Baumard

2001-01-01

292

Role of catechol structure in the adsorption and transformation reactions of L-DOPA in soils.  

PubMed

3-(3',4'-Dihydroxyphenyl)-L-alanine (L-DOPA), which is synthesized in velvet bean (Mucuna pruriens), inhibits plant growth. The concentration of L-DOPA in soil is reduced by adsorption and transformation reactions, which can result in the reduction of its plant-growth-inhibitory activity. To determine which part of the L-DOPA structure is involved in the adsorption and soil transformation reactions, we compared the kinetics of L-DOPA disappearance in a volcanic ash soil with that of L-phenylalanine (3-phenyl-L-alanine) and L-tyrosine (3-(4'-hydroxyphenyl)-L-alanine), compounds that are similar in structure to L-DOPA but do not have a catechol (o-dihydroxybenzene) moiety. L-Phenylalanine and L-tyrosine were not adsorbed and transformed in the soil at equilibrium pH values between 4 and 7. These results suggest that the adsorption and transformation reactions of L-DOPA in the soil involve the catechol moiety and not the amino and carboxylic acid groups, which are common to all three compounds. Like L-DOPA, (+)-catechin, another allelochemical that contains a catechol moiety, underwent adsorption and soil transformation reactions. Thus, we concluded that the concentrations of allelochemicals bearing a catechol moiety in soils will decrease rapidly owing to adsorption and transformation reactions, and this decrease will be faster in soils with a high pH value or high adsorption ability. Owing to this decrease in concentration, allelopathic phenomena may not occur. PMID:17195117

Furubayashi, Akihiro; Hiradate, Syuntaro; Fujii, Yoshiharu

2006-12-29

293

Catechol cytotoxicity in vitro: Induction of glioblastoma cell death by apoptosis  

Microsoft Academic Search

The exposure to benzene is a public health problem. Although the most well-known effect of benzene is hematopoietic toxicity, there is little information about the benzene and its metabolites effects on the central nervous system (CNS). This study examined the toxic effects of 1,2-dihydroxybenzene (catechol), a benzene metabolite, to human glioblastoma GL-15 cells. GL-15 cell cultures were used as a

DM de Oliveira; BPS Pitanga; Grangeiro; RMF Lima; MFD Costa; SL Costa; J. Claręncio; RS El-Bachá

2010-01-01

294

Regulation of Dopamine-Induced Natriuresisby the Dopamine-Metabolizing Enzyme Catechol-O-Methyltransferase  

Microsoft Academic Search

Dopamine (DA) is an intrarenal natriuretic hormone involved in sodium homeostasis. A study was performed to elucidate two possible regulatory pathways of DA-induced natriuresis, i.e., metabolism and precursor delivery. This was done by use of an intraperitoneal injection of a catechol-O-methyltransferase (COMT) inhibitor, entacapone, or intravenous infusion of the DA precursor, L-dopa. Entacapone (30 mg\\/kg i.p.) induced a more than

Cecilia Odlind; Viktoria Göransson; Ilkka Reenilä; Peter Hansell

1999-01-01

295

Systemic acidosis after controlled hypotension activates catechol activity in the vasomotor center.  

PubMed

Activation of the catechol metabolism, assessed with in vivo voltammetry, in the vasopressor area of the vasomotor center was investigated during systemic acidosis occurring after controlled hypotension. Rats anesthetized with halothane were mechanically ventilated. Sodium nitroprusside lowered mean arterial pressure to 55 mmHg for > or = 20 min. Arterial blood gases allowed us to group rats according to whether they showed symptoms of metabolic acidosis (pH < or = 7.34) immediately after controlled hypotension. To assess the effect of systemic acidosis independently of the progressive decline in pressure observed during the recovery period after controlled hypotension, we used phenylephrine infusion to maintain mean arterial pressure at baseline pressure during the recovery period after controlled hypotension in two groups of animals. Systemic acidosis increased the catechol signal in a prolonged manner [nitroprusside with acidosis (n = 7) vs. nitroprusside without acidosis (n = 5); P < 0.0001]. This catechol activation was greater when pressure was restored after hypotension [nitroprusside with acidosis plus phenylephrine (n = 5) vs. nitroprusside with acidosis over the whole interval (from -30 to +150 min); P < 0.05]. When the nitroprusside with acidosis group and nitroprusside with acidosis plus phenylephrine group were compared, hypercapnia had an involvement in the larger increase of the catechol signal observed in the nitroprusside with acidosis plus phenylephrine group [arterial PCO2: nitroprusside with acidosis vs. nitroprusside with acidosis plus phenylephrine over the whole interval (from -30 to +150 min) and at +30 and +60 min; all P < 0.05].(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7928888

Bruandet, N; Quintin, L

1994-06-01

296

Identification and Characterization of Integron-Mediated Antibiotic Resistance in the Phytopathogen Xanthomonas oryzae pv. oryzae  

PubMed Central

Four streptomycin-resistant isolates of Xanthomonas oryzae pv. oryzae (YNA7-1, YNA10-2, YNA11-2, and YNA12-2) were examined via PCR amplification for the presence of class 1, class 2, and class 3 integrons and aadA1 and aadA2 genes, which confer resistance to streptomycin and spectinomycin. The class 1 integrase gene intI1 and the aminoglycoside adenylyltransferase gene aadA1 were identified in all four resistant isolates but not in 25 sensitive isolates. PCR amplifications showed that 7790-bp, 7162-bp, 7790-bp, and 7240-bp resistance integrons with transposition gene modules (tni module) in 3? conserved segments existed in YNA7-1, YNA10-2, YNA11-2, and YNA12-2, respectively. Subsequent analysis of sequences indicated that the integrons of YNA7-1 and YNA11-2 carried three gene cassettes in the order |aacA3|arr3|aadA1|. The integron of YNA10-2 carried only |arr3|aadA1| gene cassettes. The integron of YNA12-2 lacked a 550-bp sequence including part of intI1 but it still carried |aacA3|arr3|aadA1| gene cassettes. The analysis of inactive mutants and complementation tests confirmed that the aacA3 gene conferred resistance to tobramycin, kanamycin, gentamicin and netilmicin; the arr3 gene conferred resistance to rifampicin; and the aadA1 gene conferred resistance to streptomycin and spectinomycin. The resistance phenotypes of the four isolates corresponded with their resistance gene cassettes, except that YNA7-1 and YNA12-2 did not show rifampicin resistance. Sequence comparison revealed that no gene cassette array in GenBank was in the same order as in the integrons of the four resistant isolates in this study and the aadA1, which was identical in the four resistant isolates, showed 99% identity with aadA1 sequences in GenBank. The result of a stability test showed that the resistance phenotype, the aadA1 gene, and the intI1 gene were completely stable in YNA7-1 and YNA12-2 but unstable in YNA10-2 and YNA11-2. To our knowledge, this is the first report of resistance integron in a phytopathogenic bacteria.

Zhou, Ming-guo

2013-01-01

297

Production of l -lactic acid by Rhizopus oryzae using semicontinuous fermentation in bioreactor  

Microsoft Academic Search

Semicontinuous fermentation using pellets of Rhizopus oryzae has been recognized as a promising technology for l-lactic acid production. In this work, semicontinuous fermentation of R. oryzae AS 3.819 for l-lactic acid production has been developed with high l-lactic acid yield and volumetric productivity. The effects of factors such as inoculations, CaCO3 addition time, and temperature on l-lactic acid yield and R. oryzae morphology

Xuefeng Wu; Shaotong Jiang; Mo Liu; Lijun Pan; Zhi Zheng; Shuizhong Luo

2011-01-01

298

Rhizomucor miehei triglyceride lipase is processed and secreted from transformed Aspergillus oryzae  

Microsoft Academic Search

The cDNA encoding the precursor of theRhizomucor miehei triglyceride lipase was inserted in anAspergillus oryzae expression vector. In this vector the expression of the lipase cDNA is under control of theAspergillus oryzae ?-amylase gene promoter and theAspergillus niger glucoamylase gene terminator. The recombinant plasmid was introduced intoAspergillus oryzae, and transformed colonies were selected and screened for lipase expression. Lipase-positive transformants

Birgitte Huge-Jensen; Frank Andreasen; Tove Christensen; Mogens Christensen; Lars Thim; Esper Boel

1989-01-01

299

Iron Traffics in Circulation Bound to a Siderocalin (Ngal)-Catechol Complex  

PubMed Central

The lipocalins are secreted proteins that bind small organic molecules. Scn-Ngal [known as Neutrophil Gelatinase Associated Lipocalin, Siderocalin, Lipocalin 2] sequesters bacterial iron chelators, called siderophores, and consequently blocks bacterial growth. However, Scn-Ngal is also prominently expressed in aseptic diseases, implying that it binds additional ligands and serves additional functions. Using chemical screens, crystallography, and fluorescence methods, we report that Scn-Ngal binds iron together with a small metabolic product called catechol. The formation of the complex blocked the reactivity of iron and permitted its transport once introduced into circulation in vivo. Scn-Ngal then recycled its iron in endosomes by a pH sensitive mechanism. Since catechols derive from bacterial and mammalian metabolism of dietary compounds, the Scn-Ngal:catechol:iron complex represents an unforeseen microbial-host interaction, which mimics Scn-Ngal:siderophore interactions, but instead traffics iron in aseptic tissues. These results identify an endogenous siderophore, which may link the disparate roles of Scn-Ngal in different diseases.

Bao, Guanhu; Clifton, Matthew; Hoette, Trisha M.; Mori, Kiyoshi; Deng, Shi-Xian; Qiu, Andong; Viltard, Melanie; Williams, David; Paragas, Neal; Leete, Thomas; Kulkarni, Ritwij; Li, Xiangpo; Lee, Belinda; Kalandadze, Avtandil; Ratner, Adam J.; Pizarro, Juan Carlos; Schmidt-Ott, Kai M.; Landry, Donald W.; Raymond, Kenneth N.; Strong, Roland K.; Barasch, Jonathan

2010-01-01

300

Hydroxylation of phenol to catechol by Candida tropicalis: involvement of cytochrome P450.  

PubMed

Microsomal preparations isolated from yeast Candida tropicalis (C. tropicalis) grown on three different media with or without phenol were isolated and characterized for the content of cytochrome P450 (CYP) (EC 1.14.15.1). While no CYP was detected in microsomes of C. tropicalis grown on glucose as the carbon source, evidence was obtained for the presence of the enzyme in the microsomes of C. tropicalis grown on media containing phenol. Furthermore, the activity of NADPH: CYP reductase, another enzyme of the microsomal CYP-dependent system, was markedly higher in cells grown on phenol. Microsomes of these cells oxidized phenol. The major metabolite formed from phenol by microsomes of C. tropicalis was characterized by UV/vis absorbance and mass spectroscopy as well as by the chromatographic properties on HPLC. The characteristics are identical to those of catechol. The formation of catechol was inhibited by CO, the inhibitor of CYP, and correlated with the content of cytochrome P450 in microsomes. These results, the first report showing the ring hydroxylation of phenol to catechol with the microsomal enzyme system of C. tropicalis, strongly suggest that CYP-catalyzed reactions are responsible for this hydroxylation. The data demonstrate the progress in resolving the enzymes responsible for the first step of phenol degradation by the C. tropicalis strain. PMID:14661729

Stiborová, M; Suchá, V; Miksanová, M; Páca, J; Páca, J

2003-06-01

301

Lycopene and beta-carotene ameliorate catechol estrogen-mediated DNA damage.  

PubMed

The consumption of fruits and vegetables is associated with a reduced risk of various ailments, including cancer and cardiovascular diseases. Carotenoids, such as lycopene and beta-carotene, are natural constituents of edible plants and may protect against disease. In this study, the influence of lycopene and beta-carotene on DNA damage caused by catechol-estrogens in vitro is examined. One possible mechanism by which catechol estrogens such as 4-hydroxyestradiol (4-OHE2) and 2-hydroxyestradiol, which cause DNA damage in naked plasmid DNA as well as in cells, contributing to the process of carcinogenesis, is through the generation of reactive oxygen species. It was found that both carotenoids at concentrations ranging from 0.25 to 10 microM significantly inhibit strand breakage induced by 4-OHE2/copper sulphate by up to approximately 90% in plasmid DNA with beta-carotene being slightly more effective. No prooxidant or cytotoxic effects were observed at the concentrations tested. These carotenoids had a similar, though reduced effect on DNA damage as measured by the comet assay, in Chinese hamster lung fibroblasts. The results obtained show that both lycopene and beta-carotene, most probably and mainly through their potent antioxidant properties, are able to inhibit catechol-estrogen-mediated DNA damage. PMID:15822859

Muzandu, Kaampwe; El Bohi, Khlood; Shaban, Zein; Ishizuka, Mayumi; Kazusaka, Akio; Fujita, Shoichi

2005-02-01

302

Characterization of SafC, a Catechol 4-O-Methyltransferase Involved in Saframycin Biosynthesis?  

PubMed Central

Members of the saframycin/safracin/ecteinascidin family of peptide natural products are potent antitumor agents currently under clinical development. Saframycin MX1, from Myxococcus xanthus, is synthesized by a nonribosomal peptide synthetase, SafAB, and an O-methyltransferase, SafC, although other proteins are likely involved in the pathway. SafC was overexpressed in Escherichia coli, purified to homogeneity, and assayed for its ability to methylate a variety of substrates. SafC was able to catalyze the O-methylation of catechol derivatives but not phenols. Among the substrates tested, the best substrate for SafC was l-dihydroxyphenylalanine (l-dopa), which was methylated specifically in the 4?-O position (kcat/Km = 5.5 × 103 M?1 s?1). SafC displayed less activity on other catechol derivatives, including catechol, dopamine, and caffeic acid. The more labile l-5?-methyldopa was an extremely poor substrate for SafC (kcat/Km = ?2.8 × 10?5 M?1 s?1). l-Dopa thioester derivatives were also much less reactive than l-dopa. These results indicate that SafC-catalyzed 4?-O-methylation of l-dopa occurs prior to 5?-C-methylation, suggesting that 4?-O-methylation is likely the first committed step in the biosynthesis of saframycin MX1. SafC has biotechnological potential as a methyltransferase with unique regioselectivity.

Nelson, James T.; Lee, Jaeheon; Sims, James W.; Schmidt, Eric W.

2007-01-01

303

Catechol-initiated polyethers: multifunctional hydrophilic ligands for PEGylation and functionalization of metal oxide nanoparticles.  

PubMed

Bifunctional CA-PEG (catechol-poly(ethylene glycol)) and multifunctional CA-PEG-PGA/PEVGE (poly(glycidyl amine)/poly(ethylene glycol vinyl glycidyl ether)) ligands for the functionalization and solubilization of nanoparticles are introduced. Tunable polymers with polydispersities <1.25 and molecular weights in the range 500-7700 g mol(-1) containing a catechol moiety for conjugation to metal oxide nanoparticles were prepared. The functional PEG ligands were synthesized starting from the acetonide-protected catechol initiator 2,2-dimethyl-1,3-benzodioxole-5-propanol (CA-OH) for oxyanionic polymerization. CA-OH was used both for homopolymerization of ethylene oxide (EO) as well as copolymerization with functional epoxides N,N-diallyl glycidyl amine (DAGA), releasing primary amino groups and ethylene glycol vinyl glycidyl ether (EVGE), exhibiting a double bond for click-type reactions, to generate CA-PEG and CA-PEG-PGA/PEVGE. We demonstrate the potential of the functional ligands by binding to MnO nanoparticles, rendering the PEGylated nanoparticles highly stable in aqueous environment. Furthermore, addressability of the functional groups has been proven, for example, by coupling with fluoresceine isothiocyanate (FITC), to allow for optical monitoring of the nanoparticle fate in biological systems. PMID:23210706

Wilms, Valerie S; Bauer, Heiko; Tonhauser, Christine; Schilmann, Anna-Maria; Müller, Marc-Christian; Tremel, Wolfgang; Frey, Holger

2012-12-20

304

Purification and Characterization of Catechol 1,2Dioxygenase from Acinetobacter sp. DS002 and Cloning, Sequencing of Partial catA Gene  

Microsoft Academic Search

Catechol 1,2-dioxygenase (C12O) was purified to electrophoretic homogeneity from Acinetobacter sp. DS002. The pure enzyme appears to be a homodimer with a molecular mass of 66 kDa. The apparent Km and Vmax for intradiol cleavage of catechol were 1.58 ?M and 2 units per mg of protein respectively. Unlike other C12Os reported in\\u000a the literature, the catechol 1,2-dioxygenase of Acinetobacter showed neither

Emmanuel Vijay Paul Pandeeti; Dayananda Siddavattam

305

Photoreactions of cytochrome C oxidase.  

PubMed

The photoreduction of oxidized bovine heart cytochrome c oxidase (CcO) by visible and UV radiation was investigated in the absence and presence of external reagents. In the former case, the quantum yields for direct photoreduction of heme A (heme a + heme a(3)) were 2.6 +/- 0.5 x 10(-3), 4 +/- 1 x 10(-4), and 4 +/- 2 x 10(-6) with pulsed laser irradiation at 266, 355 and 532 nm, respectively. Within experimental uncertainty, the quantum yields did not depend on pulse energy, implying that the mechanism is monophotonic. Irradiation with 355 nm light resulted in spectral changes similar to those produced independently by reduction with dithionite, whereby the low-spin heme a and Cu(A) are reduced first. Extended illumination at 355 and 532 nm yielded substantial amounts of reduced heme a(3). Heme decomposition was noted with 266 nm light. In the presence of formate and cyanide ions, which bind at the binuclear heme a(3)/copper center in CcO, irradiation at 355 nm caused selective reduction of only the low-spin heme a and Cu(A). The addition of ferrioxalate ion dramatically increased the efficiency of cytochrome c oxidase photoreduction. The quantum efficiency for heme A reduction was found to be near unity, significantly greater than for other known methods of photoreduction. The active reductant is most likely ferrous iron, and its reduction of the enzyme is thermodynamically driven by the reformation of ferrioxalate in the presence of excess oxalate ion. Other metalloenzymes with redox potentials similar to those of cytochrome c oxidase should be amenable to indirect photoreduction by this method. PMID:16789843

Winterle, John S; Einarsdóttir, Olöf

306

Studies on the Mechanism of Aldehyde Oxidase and Xanthine Oxidase  

PubMed Central

DFT calculations support a concerted mechanism for xanthine oxidase and aldehyde oxidase hydride displacement from the sp2 carbon of 6-substituted 4-quinazolinones. The variations in transition state structure show that C-O bond formation is nearly complete in the transition state and the transition state changes are anti-Hammond with the C-H and C-O bond lengths being more product-like for the faster reactions. The C-O bond length in the transition state is around 90% formed. However, the C-H bond is only about 80% broken. This leads to a very tetrahedral transition state with an O-C-N angle of 109 degrees. Thus, while the mechanism is concerted, the anti-bonding orbital of the C-H bond that is broken is not directly attacked by the nucleophile and instead hydride displacement occurs after almost complete tetrahedral transition state formation. In support of this the C=N bond is lengthened in the transition state indicating that attack on the electrophilic carbon occurs by addition to the C=N bond with negative charge increasing on the nitrogen. Differences in experimental reaction rates are accurately reproduced by these calculations, and tend to support this mechanism.

Alfaro, Joshua F.

2009-01-01

307

Identification and metabolite profiling of Sitophilus oryzae L. by 1D and 2D NMR spectroscopy.  

PubMed

The polyphagous insect Sitophilus oryzae L. (Coleoptera:Curculionidae) has a tremendous adaptability in feeding behaviour, making it a serious invasive pest of stored cereals. The present study identifies the metabolite composition of Sitophilus oryzae (S. oryzae) using Nuclear Magnetic Resonance (NMR) spectroscopy. Assignment of 1D-proton by NMR, 1H-1H COSY, 2D-TOCSY 1H-1H, had been done. Amongst the various biochemically important metabolites isoleucine, valine, leucine, beta-hydroxybutyrate, lysine, glutamate, glutamine, proline, lactate, alanine, di-methylamine, alpha-glucose, beta-glucose, choline, glycerophosphorylcholine and tyrosine are present in S. oryzae. In wheat-fed S. oryzae, the presence of threonine and the absence of lactate is observed. In rice-fed S. oryzae, however, the presence of lactate and the absence of threonine were observed. Barley-fed S. oryzae shows presence of both tyrosine and lactate. It is concluded that the pest S. oryzae has adaptability on different stored cereals and grains, depicting the presence of earlier reported metabolites. The present study aims to identify the key metabolic components and associated enzymes in Sitophilus oryzae fed on different cereals. PMID:19814847

Trivedi, A; Kaushik, P; Pandey, A

2009-10-09

308

What does genetic diversity of Aspergillus flavus tell us about Aspergillus oryzae?  

PubMed

Aspergillus flavus and Aspergillus oryzae belong to Aspergillus section Flavi. They are closely related and are of significant economic importance. The former species has the ability to produce harmful aflatoxins while the latter is widely used in food fermentation and industrial enzyme production. This review summarizes the current understanding of the similarity of the A. flavus and A. oryzae genomes, the genetic diversity in A. flavus and A. oryzae populations, the causes of this diversity, and the relatedness of nonaflatoxigenic A. flavus strains to A. oryzae. PMID:20163884

Chang, Perng-Kuang; Ehrlich, Kenneth C

2010-02-01

309

Alternative oxidase and uses thereof  

US Patent & Trademark Office Database

The invention relates to a method for combating disorders affecting the mitochondrial oxidative phosphorylation system by allotopic expression of the cyanide-insensitive alternative oxidase (AOX) in human cells. The successful expression of AOX in human cells and in Drosophila has been shown to confer spectacular cyanide-resistance to mitochondrial substrate oxidation, alleviate oxidative stress, apoptosis susceptibility and metabolic acidosis. AOX is well tolerated when expressed ubiquitously in the whole organism. AOX expression is a valuable tool to limit the deleterious consequences of respiratory chain deficiency.

2009-08-11

310

Glucose oxidase activity of actinomycetes.  

PubMed

The ability of 311 actiomycete, belonging to 12 species to produce glucose oxidase was studied. It was found that 174 of them formed exoenzymes on solid medium and 133 in liquid medium. The composition of the nutrient medium has an essential effect on the amount of enzyme formed. Strains with considerably higher activity form a greater amount of exoenzymes on soya meal medium and on synthetic medium with KNO2. The highest activity of the culture liquid of some strains was observed between the 6th and 7th day of cultivation. During this phase of growth the highest productivity of the biomas was established. PMID:76424

St Vlahov, S

1978-01-01

311

Hyperuricemia and xanthine oxidase in preeclampsia, revisited  

Microsoft Academic Search

Hyperuricemia is associated with the severity of preeclampsia and with fetal outcome. Traditionally the high uric acid concentration in preeclampsia has been attributed solely to renal dysfunction. Preeclampsia is also characterized by increased free radical formation and elevated oxidative stress. Xanthine dehydrogenase\\/oxidase produces uric acid. Xanthine dehydrogenase\\/oxidase is present as two isoforms in vivo. Uric acid production is coupled with

A. Many; C. A. Hubel; J. M. Roberts

1996-01-01

312

The bacterial cytochrome cbb3 oxidases.  

PubMed

Cytochrome cbb(3) oxidases are found almost exclusively in Proteobacteria, and represent a distinctive class of proton-pumping respiratory heme-copper oxidases (HCO) that lack many of the key structural features that contribute to the reaction cycle of the intensely studied mitochondrial cytochrome c oxidase (CcO). Expression of cytochrome cbb(3) oxidase allows human pathogens to colonise anoxic tissues and agronomically important diazotrophs to sustain N(2) fixation. We review recent progress in the biochemical characterisation of these distinctive oxidases that lays the foundation for understanding the basis of their proposed high affinity for oxygen, an apparent degeneracy in their electron input pathways and whether or not they acquired the ability to pump protons independently of other HCOs. PMID:15100055

Pitcher, Robert S; Watmough, Nicholas J

2004-04-12

313

Purification, characterization and immobilization of a keratinase from Aspergillus oryzae  

Microsoft Academic Search

A keratinase enzyme was isolated and purified from a feather-degrading culture of Aspergillus oryzae. Fractional precipitation of the crude enzyme with ethanol, acetone and ammonium sulfate yielded 21 fractions. The fraction obtained at 75–85% ammonium sulfate saturation showed the highest activity and about 3.3-fold purification. This fraction was further purified by gel filtration in Sephadex G-75 followed by ion exchange

Aida M Farag; Maha A Hassan

2004-01-01

314

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

315

Genetic studies of rice (Oryza sativa L.) anther culture response  

Microsoft Academic Search

Anthers of two rice (Oryza sativa L.) varieties, Lunhui 422 (P1) and Jinzao 5 (P2), their F1, F2 and first backcross generation-F1 x Lunhui 422 (B1), and F1 x Jinzao 5 (B2)-were cultured in L8 medium to study the inheritance of rice anther culturability using generation mean analysis. Significant effects of generation were observed for the four traits measured: anther

Chen Zhang; Chen Qifeng

1993-01-01

316

Isolation of gametes and central cells from Oryza sativa L  

Microsoft Academic Search

In vitro fertilization system of higher plants has been well established using maize gametes and central cells, which can\\u000a produce embryos and endosperms. In the present study, procedures for isolating gametes and central cells from rice (Oryza sativa L. cv. Nipponbare), a model plant, are reported with the goal of establishing rice in vitro fertilization system. Egg cells\\u000a and central

Takao Uchiumi; Setsuko Komatsu; Tomokazu Koshiba; Takashi Okamoto

2006-01-01

317

Mitochondrial DNA RFLP in genus Oryza and cultivated rice  

Microsoft Academic Search

Ninety-three accessions representing 23 species from the genus Oryza were surveyed for restriction fragment length polymorphism (RFLP) in mitochondrial (mt) DNA by probing total DNA with 15 known mt sequences cloned in plasmids from higher plants, and five mt genomic cosmid clones from maize. Very low levels of intra-specific and even intra-cytologically-defined nuclear genome mt DNA RFLP were found. High

G. Second; Z. Y. Wang

1992-01-01

318

Chromosomal regions controlling anther culturability in rice (Oryza sativa L.)  

Microsoft Academic Search

Diallel analysis has revealed that anther culturability in rice (Oryza sativa L.) is a quantitative trait controlled by the\\u000a nuclear genome. Mapping of anther culturability is important to increase the efficiency for green plant regeneration from\\u000a microspores. In the previous study, we detected distorted segregation of RFLP markers in rice populations derived from the\\u000a anther culture of an F1 hybrid

Masumi Yamagishi; Motoyasu Otani; Mariko Higashi; Yoshimichi Fukuta; Kiichi Fukui; Takiko Shimada

1998-01-01

319

High ethanol yields using Aspergillus oryzae koji and corn media  

Microsoft Academic Search

High ethanol and stillage solids have been achieved using whole corn mashes. Ethanol yields of 14% (v\\/v) (89.5% of theory) and stillage levels of approximately 23% (w\\/v) were obtained in 74–90 hours using mild acid pretreatment with Aspergillus oryzae wheat bran koji saccharification. High ethanol yields were also obtained with bacterial amylase, instead of the acid treatment, when the sterilization

Jack Ziffer; Mario C. Iosif

1982-01-01

320

Plant regeneration from cytoplasmic hybrids of rice ( Oryza sativa L.)  

Microsoft Academic Search

We obtained cybrid plants by electrofusing ?-irradiated protoplasts of a cytoplasmic male-sterile line “A-58 CMS” (Oryza sativa L.) and iodoacetamide (IOA)-treated protoplasts of the fertile (normal) rice cultivar “Fujiminori”. The cybridity of the plants was confirmed by mitochondrial (mt) DNA restriction endonuclease, and plasmid-like DNA analyses, and by isozyme, cytological and morphological investigations. The chromosome number of the cybrid plants

Z.-Q. Yang; T. Shikanai; K. Mori; Y. Yamada

1989-01-01

321

Intervention of glutathione in pre-mutagenic catechol-mediated DNA damage in the presence of copper(II) ions.  

PubMed

The catechol-mediated DNA damage in the presence of Cu(II) ions involves oxidation of guanine to 8-oxoguanine (8-oxoG) and DNA strand scission. It proceeds through the reactive oxygen species (ROS) generation. The mutagenicity of 8-oxoG lesions is due to its miscoding propensity reflected in GC?TA transversion taking place during the DNA repair process. To gain new insights into the nature of catechol-mediated DNA damage and its prevention, we have investigated the changes in DNA melting characteristics and 8-oxoG formation as the indicators of DNA damage in a model calf-thymus DNA system. A novel fluorescence method for DNA melting temperature determination, based on DAPI fluorescent-probe staining, has been proposed. The DNA melting-onset temperature has been found to be more sensitive to DNA damage than the standard melting temperature due to the increased width of the melting transition observed in oxidatively damaged DNA. We have found that the efficiency of Fenton cascade in generating DNA-damaging ROS is higher for catechol than for GSH, two strong antioxidants, mainly due to the much longer distance between ROS-generating radical group in GS to nucleobases than that of semiquinone radical group to nucleobases (2.1nm vs. 0.27nm), making the ROS transport from GSH an order of magnitude less likely to damage DNA because of short lifetime of HO radicals. The antioxidant and DNA-protecting behaviors of GSH have been elucidated. We have found that the redox potential of GSH/GSSG couple is lower than that of catechol/semiquinone couple. Hence, GSH keeps catechol in the reduced state, thereby shutting down the initial step of the catechol-mediated Fenton cascade. The catechol-induced DNA damage in the presence of Cu(II) ions has also been confirmed in studies of ON-OFF hairpin-oligonucleotide beacons. PMID:22683503

Hepel, Maria; Stobiecka, Magdalena; Peachey, Janet; Miller, Jeremiah

2012-06-06

322

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

323

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

Microsoft Academic Search

Aspergillus oryzae NRRL 35191 was isolated as an endophyte from coffee leaves and found to produce kojic acid (KA) in culture. When inoculated\\u000a into cacao seedlings (Theobroma cacao), A. oryzae grew endophytically and synthesized KA in planta. Cacao seedlings inoculated with A. oryzae produced higher levels of caffeine than non-inoculated ones. Aspergillus oryzae may be a useful endophyte to introduce

Fabio C. Chaves; Thomas J. Gianfagna; Madhu Aneja; Francisco Posada; Stephen W. Peterson; Fernando E. Vega

324

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

325

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

326

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

327

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

328

Identification of two novel hrp-associated genes in the hrp gene cluster of Xanthomonas oryzae pv. oryzae.  

PubMed

We have cloned a hrp gene cluster from Xanthomonas oryzae pv. oryzae. Bacteria with mutations in the hrp region have reduced growth in rice leaves and lose the ability to elicit a hypersensitive response (HR) on the appropriate resistant cultivars of rice and the nonhost plant tomato. A 12,165-bp portion of nucleotide sequence from the presumed left end and extending through the hrpB operon was determined. The region was most similar to hrp genes from Xanthomonas campestris pv. vesicatoria and Ralstonia solanacearum. Two new hrp-associated loci, named hpa1 and hpa2, were located beyond the hrpA operon. The hpa1 gene encoded a 13-kDa glycine-rich protein with a composition similar to those of harpins and PopA. The product of hpa2 was similar to lysozyme-like proteins. Perfect PIP boxes were present in the hrpB and hpa1 operons, while a variant PIP box was located upstream of hpa2. A strain with a deletion encompassing hpa1 and hpa2 had reduced pathogenicity and elicited a weak HR on nonhost and resistant host plants. Experiments using single mutations in hpa1 and hpa2 indicated that the loss of hpa1 was the principal cause of the reduced pathogenicity of the deletion strain. A 1,519-bp insertion element was located immediately downstream of hpa2. Hybridization with hpa2 indicated that the gene was present in all of the strains of Xanthomonas examined. Hybridization experiments with hpa1 and IS1114 indicated that these sequences were detectable in all strains of X. oryzae pv. oryzae and some other Xanthomonas species. PMID:10714988

Zhu, W; MaGbanua, M M; White, F F

2000-04-01

329

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...

330

Ultrasensitive voltammetric determination of catechol at a gold atomic cluster/poly(3,4-ethylenedioxythiophene) nanocomposite electrode.  

PubMed

A novel gold atomic cluster-poly(3,4-ethylenedioxythiophene) (AuAC/PEDOT/Au) nanocomposite modified gold electrode has been designed for the trace level sensing of catechol. The addition of copper(II) enhanced the electro-catalytic oxidation of catechol via the formation of copper(I). The electrochemically synthesized PEDOT/Au and the AuAC/PEDOT/Au hybrid films were characterized by electrochemical and morphological methods. Under optimal conditions the nanocomposite modified electrode offers a wider calibration range of 1 × 10(-4) to 10 ?M with a lowest detection limit of 6.3 pM for catechol. Moreover, the developed electrochemical sensor exhibited good selectivity and acceptable reproducibility (1.23% for 1 nM of catechol) and could be used for the routine detection and quantification of catechol in natural water samples. To gain a better understanding of such an excellent sensor performance achieved with this electrode, studies were undertaken to pinpoint electrode kinetics of charge transfer processes. PMID:23826610

Nambiar, Sindhu R; Aneesh, Padamadathil K; Rao, Talasila P

2013-07-03

331

Riboflavin kinase couples TNF receptor 1 to NADPH oxidase  

Microsoft Academic Search

Reactive oxygen species (ROS) produced by NADPH oxidase function as defence and signalling molecules related to innate immunity and various cellular responses. The activation of NADPH oxidase in response to plasma membrane receptor activation depends on the phosphorylation of cytoplasmic oxidase subunits, their translocation to membranes and the assembly of all NADPH oxidase components. Tumour necrosis factor (TNF) is a

Benjamin Yazdanpanah; Katja Wiegmann; Vladimir Tchikov; Oleg Krut; Carola Pongratz; Michael Schramm; Andre Kleinridders; Thomas Wunderlich; Hamid Kashkar; Olaf Utermöhlen; Jens C. Brüning; Stefan Schütze; Martin Krönke

2009-01-01

332

Efficient and selective microbial esterification with dry mycelium of Rhizopus oryzae  

Microsoft Academic Search

The use of dry mycelium of Rhizopus oryzae as biocatalyst for ester production in organic solvent has been studied. Mycelia with notable carboxylesterase activity were produced when different Tweens (20, 40, 60 and 80) were employed as main carbon source for the growth. Dry mycelium of four strains of Rhizopus oryzae proved effective for efficiently catalysing the synthesis of different

Raffaella Gandolfi; Attilio Converti; Domenico Pirozzi; Francesco Molinari

2001-01-01

333

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

334

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

335

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...

336

Rubisco activity is associated with photosynthetic thermotolerance in a wild rice (Oryza meridionalis)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Oryza meridionalis is a wild species of rice, endemic to tropical Australia. It shares a significant genome homology with the common domesticated rice Oryza sativa. Exploiting the fact that the two species are highly related but O. meridionalis has superior heat tolerance, experiments were undertake...

337

New insights into Oryza genome evolution: high gene colinearity and differential retrotransposon amplification  

Technology Transfer Automated Retrieval System (TEKTRAN)

A genomic region (~247kb) from an FF genome, wild Oryza species, O. brachyantha L., was sequenced and compared to the orthologous region (~450 kb) from AA genome rice, O. sativa L. ssp japonica ¬ the first such comparison reported between cultivated Oryza and a distantly related wild species. Among ...

338

Exploring the use of Oryza species to enhance the lipid fraction of cultivated rice  

Technology Transfer Automated Retrieval System (TEKTRAN)

In the past few several years, efforts to collect rice germplasm were broadened to collect more widely from the Oryza genepool. The Oryza genus includes only 23 species, but it is remarkably diverse in-terms of its ecological adaptation. This diversity may not only be restricted to ecological charac...

339

Production of lactic acid from xylose and wheat straw by Rhizopus oryzae.  

PubMed

Rhizopus oryzae NBRC 5378 was the best among 56 strains of R. oryzae for the production of lactic acid from xylose. This strain produced lactic acid from wheat straw powder by a simultaneous saccharification and fermentation process, with a yield of 0.23 g/g from cellulose and hemicellulose in wheat straw. PMID:22578599

Saito, Katsuichi; Hasa, Yasuhiro; Abe, Hideyuki

2012-05-10

340

NADPH Oxidases and Angiotensin II Receptor Signaling  

PubMed Central

Over the last decade many studies have demonstrated the importance of reactive oxygen species (ROS) production by NADPH oxidases in angiotensin II (Ang II) signaling, as well as a role for ROS in the development of different diseases in which Ang II is a central component. In this review, we summarize the mechanism of activation of NADPH oxidases by Ang II and describe the molecular targets of ROS in Ang II signaling in the vasculature, kidney and brain. We also discuss the effects of genetic manipulation of NADPH oxidase function on the physiology and pathophysiology of the renin angiotensin system.

Garrido, Abel Martin; Griendling, Kathy K.

2010-01-01

341

Regulation of expression of the Rhizopus oryzae uricase and urease enzymes.  

PubMed

The regulation of intracellular urease and uricase activities was examined in Rhizopus oryzae. Urease activity (2.4 U/mg protein) was present in R. oryzae mycelium grown in minimal medium containing NH4CI as sole nitrogen source. This activity increased threefold under nitrogen derepression conditions, but no induction by urea was detected. Control of urease activity in R. oryzae differs from that found in Neurospora crassa but resembles the situation in Aspergillus nidulans. No uricase activity was detected in R. oryzae mycelium grown in minimal medium containing NH4Cl as sole nitrogen source. Uricase activity was increased 10- to 40-fold under derepression conditions and was induced by exogenous uric acid (60- to 78-fold). Control of the R. oryzae uricase differs from that found in N. crassa and A. nidulans. This is the first analysis of the regulation of enzymes from the purine catabolic pathway in any member of the Zygomycetes. PMID:12619824

Farley, Peter C; Santosa, Sugiarto

2002-12-01

342

Phorbol myristate acetate and catechol as skin cocarcinogens in SENCAR mice  

SciTech Connect

The enhancement of the carcinogenicity of benzo(a) pyrene (B(a)P) and ..beta..-propiolactone (BPL) by the mouse skin cocarcinogens phorbol myristate acetate (PMA) and catechol were examined in female SENCAR mice, 30 per group. The carcinogen and cocarcinogen were applied simultaneously, three times weekly for 490-560 days. B(a)P and BPL were used at constant doses of 5 and 50 ..mu..g, respectively, in all experiments. PMA was used at three doses, 2.5, 1.0, and 0.5 ..mu..g per application, and catechol was used at one dose, 2 mg per application. Control groups included animals that received carcinogen only, cocarcinogen only, acetone only, and no treatment. The carcinogenicity of B(a)P and BPL were enhanced by the cocarcinogens, particularly in terms of tumor multiplicity. For both carcinogens, the most marked cocarcinogenic effects were observed at the lowest dose of PMA used (0.5 ..mu..g per application). This observation applied for days to first tumor, animals with tumors, tumor multiplicity, and incidence of malignant skin tumors. Catechol applied alone did not induce any tumors; with PMA alone there were significant incidences of benign and malignant tumors, e.g., at a dose of only 0.5 ..mu..g per application, 15 of 30 animals had 28 tumors, 5 of which were squamous carcinomas. In two-stage carcinogenesis experiments with 7,12-dimethylbenz(a)anthracene (DMBA) as initiator and PMA as promoter, SENCAR mice showed a greater susceptibility to tumor induction when compared to ICR/Ha mice used in earlier work. This susceptibility was most notable in terms of rate of tumor appearance and tumor multiplicity.

Van Duuren, B.L.; Melchionne, S.; Seidman, I.

1986-09-01

343

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

344

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.

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

2011-01-01

345

In vitro effect of haloperidol, chlorpromazine, imipramine and lithium on the erythrocyte catechol-O-methyltransferase.  

PubMed

Haloperidol, chlorpromazine, imipramine and lithium in concentrations similar to the average therapeutic plasma levels did not exert any in vitro inhibition on the erythrocyte catechol-O-methyltransferase (COMT). The inhibitory effects of haloperidol, chlorpromazine and imipramine were noted first at concentrations 1000-10 000 times their respective average therapeutic plasma levels. Unlike the former three psychotropic drugs, lithium exerted an in vitro inhibition already at a concentration 40 times the average therapeutic plasma level and that in a competitive way. The inhibitory effect of lithium could be neutralized by increasing the magnesium concentration, likewise in a competitive way. PMID:7202372

Hoo, J J; Noldt, P; Beckermann, W J; Agarwal, D P; Goedde, H W

1982-01-01

346

New semiquinone-catecholate rhodium complex with 2,2?-dipyridyl  

Microsoft Academic Search

A new semiquinone rhodium complex,viz., (2,2?-dipyridyl)(3,6-di-tert-butyl-o-benzosemiquinone)(3,6-di-tert-butylcatecholate)rhodium(III) (1), which is a structural analog of the known redox-isomeric cobalt complex, was prepared, isolated in the individual state,\\u000a and characterized by X-ray analysis, magnetochemistry, and IR and ESR spectroscopy. At room temperature, compound1, unlike the cobalt analog, is a complex of trivalent low-spin rhodium with one catecholate and one semiquinone ligand. However,\\u000a broadening

G. A. Abakumov; V. K. Cherkasov; M. P. Bubnov; L. G. Abakumova; L. N. Zakharov; G. K. Fukin

1999-01-01

347

Catechol O -methyltransferase (COMT) Val158Met polymorphism and risk of osteoporotic fracture  

Microsoft Academic Search

Catechol-O-methyltransferase (COMT) is an estrogen degrading enzyme. The COMT Val158Met polymorphism is associated with bone mineral\\u000a density. The aim of this study was to investigate associations between COMT Val158Met and osteoporotic fractures in Chinese\\u000a Han patients. Case-control study of 320 patients with osteoporotic fractures and 320 healthy controls were conducted. The\\u000a COMT Val158Met polymorphism was analyzed by polymerase chain reaction-restriction

Yang CaoDawei; Dawei Wang; Bin Liu; Guijun Yao; Yutuo Fu; Zhenggang Bi

348

Are the Dominant and Recessive Plant Disease Resistance Genes Similar?: A Case Study of Rice R Genes and Xanthomonas oryzae pv. oryzae Races  

Microsoft Academic Search

The resistance of rice to its bacterial blight pathogen Xanthomonas oryzae pv. oryzae (Xoo) has both qualitative and quantitative components that were investigated using three near-isogenic line sets for four resistance (R) genes (Xa4, xa5, xa13, and Xa21) and 12 Xoo races. Our results indicate that these two resistance components of rice plants were associated with the properties of the

Zhi-Kang Li; Alma Sanchez; E. Angeles; Sukhwider Singh; Jessica Domingo; Ning Huang; Gurdev S. Khush

349

Enhanced expression of alternative oxidase genes is involved in the tolerance of rice (Oryza sativa L.) seedlings to drought stress.  

PubMed

Drought stress significantly enhanced the capacity of the alternative respiratory pathway and induced AOX1a and AOX1b transcripts in rice seedling leaves. The drought-stressed seedlings pretreated with the inhibitor of the alternative respiratory pathway, 1 mM salicylhydroxamic acid, had a lower level of relative water content than the seedlings either subjected to drought or salicylhydroxamic acid treatment alone. This observation suggests that the alternative respiratory pathway could play a role in the tolerance of rice seedlings to drought stress. Pretreatment with exogenous hydrogen peroxide, salicylic acid, and abscisic acid alone mitigated the water loss of rice leaves exposed to drought stress. Exogenous application of hydrogen peroxide and salicylic acid increased the capacity of the alternative respiratory pathway and induced AOX1a and AOX1b transcripts, while exogenous abscisic acid failed to induce any expression of AOX1 genes. These observations suggest that rice AOX1a and AOX1b genes may be responsive especially to drought stress but not be induced by all of the stress signals related to drought. PMID:19957440

Feng, Han-Qing; Li, Hong-Yu; Sun, Kun

350

Activation of Polyphenol Oxidase of Chloroplasts 1  

PubMed Central

Polyphenol oxidase of leaves is located mainly in chloroplasts isolated by differential or sucrose density gradient centrifugation. This activity is part of the lamellar structure that is not lost on repeated washing of the plastids. The oxidase activity was stable during prolonged storage of the particles at 4 C or —18 C. The Km (dihydroxyphenylalanine) for spinach leaf polyphenol oxidase was 7 mm by a spectrophotometric assay and 2 mm by the manometric assay. Polyphenol oxidase activity in the leaf peroxisomal fraction, after isopycnic centrifugation on a linear sucrose gradient, did not coincide with the peroxisomal enzymes but was attributed to proplastids at nearly the same specific density. Plants were grouped by the latency properties for polyphenol oxidase in their isolated chloroplasts. In a group including spinach, Swiss chard, and beet leaves the plastids immediately after preparation from fresh leaves required a small amount of light for maximal rates of oxidation of dihydroxyphenylalanine. Polyphenol oxidase activity in the dark or light increased many fold during aging of these chloroplasts for 1 to 5 days. Soluble polyphenol oxidase of the cytoplasm was not so stimulated. Chloroplasts prepared from stored leaves were also much more active than from fresh leaves. Maximum rates of dihydroxyphenylalanine oxidation were 2 to 6 mmoles × mg?1 chlorophyll × hr?1. Equal stimulation of latent polyphenol oxidase in fresh or aged chloroplasts in this group was obtained by either light, an aged trypsin digest, 3-(4-chlorophenyl)-1, 1-dimethylurea, or antimycin A. A variety of other treatments did not activate or had little effect on the oxidase, including various peptides, salts, detergents, and other proteolytic enzymes. Activation of latent polyphenol oxidase in spinach chloroplasts by trypsin amounted to as much as 30-fold. The trypsin activation occurred even after the trypsin had been treated with 10% trichloroacetic acid, 1.0 n HCl or boiled for 30 minutes. No single peptide from the digested trypsin was found to be the sole activating factor. About 0.25 ?g of trypsin activated 50% the polyphenol oxidase activity in a standard chloroplast assay containing 2.1 ?g of chlorophyll. Treatment of spinach chloroplasts with tris buffer or ethylenediamine tetraacetate extracted the ATPase activity, but the polyphenol oxidase activity remained with the broken plastids. However these treatments increased the latent polyphenol oxidase activity 50- to 100-fold. Chloroplasts from a second group of plants, including alfalfa, wheat, oats, peas, and sugarcane leaves, oxidized dihydroxyphenylalanine at a rate of 11 to 120 ?moles × mg?1 chlorophyll × hr?1. Polyphenol oxidase in these chloroplasts required a low intensity of red light for activity. Fifty or 75% activation of the oxidase in wheat chloroplasts required 4 to 6 foot candles of light and more light was required for alfalfa chloroplasts. Blue or far red light were ineffective. Trypsin was inhibitory. Upon aging chloroplasts from wheat leaves, but not alfalfa or peas, for 5 to 7 days at 4 C the total polyphenol oxidase activity did not increase, but the activation characteristics changed to those of chloroplasts from the spinach group. Chloroplasts from a third group of plants, including bean, tomato, and corn leaves, slowly oxidized dihydroxyphenylalanine in the dark and exhibited no latency.

Tolbert, N. E.

1973-01-01

351

Activation of polyphenol oxidase of chloroplasts.  

PubMed

Polyphenol oxidase of leaves is located mainly in chloroplasts isolated by differential or sucrose density gradient centrifugation. This activity is part of the lamellar structure that is not lost on repeated washing of the plastids. The oxidase activity was stable during prolonged storage of the particles at 4 C or -18 C. The Km (dihydroxyphenylalanine) for spinach leaf polyphenol oxidase was 7 mm by a spectrophotometric assay and 2 mm by the manometric assay. Polyphenol oxidase activity in the leaf peroxisomal fraction, after isopycnic centrifugation on a linear sucrose gradient, did not coincide with the peroxisomal enzymes but was attributed to proplastids at nearly the same specific density.Plants were grouped by the latency properties for polyphenol oxidase in their isolated chloroplasts. In a group including spinach, Swiss chard, and beet leaves the plastids immediately after preparation from fresh leaves required a small amount of light for maximal rates of oxidation of dihydroxyphenylalanine. Polyphenol oxidase activity in the dark or light increased many fold during aging of these chloroplasts for 1 to 5 days. Soluble polyphenol oxidase of the cytoplasm was not so stimulated. Chloroplasts prepared from stored leaves were also much more active than from fresh leaves. Maximum rates of dihydroxyphenylalanine oxidation were 2 to 6 mmoles x mg(-1) chlorophyll x hr(-1). Equal stimulation of latent polyphenol oxidase in fresh or aged chloroplasts in this group was obtained by either light, an aged trypsin digest, 3-(4-chlorophenyl)-1, 1-dimethylurea, or antimycin A. A variety of other treatments did not activate or had little effect on the oxidase, including various peptides, salts, detergents, and other proteolytic enzymes.Activation of latent polyphenol oxidase in spinach chloroplasts by trypsin amounted to as much as 30-fold. The trypsin activation occurred even after the trypsin had been treated with 10% trichloroacetic acid, 1.0 n HCl or boiled for 30 minutes. No single peptide from the digested trypsin was found to be the sole activating factor. About 0.25 mug of trypsin activated 50% the polyphenol oxidase activity in a standard chloroplast assay containing 2.1 mug of chlorophyll. Treatment of spinach chloroplasts with tris buffer or ethylenediamine tetraacetate extracted the ATPase activity, but the polyphenol oxidase activity remained with the broken plastids. However these treatments increased the latent polyphenol oxidase activity 50- to 100-fold.Chloroplasts from a second group of plants, including alfalfa, wheat, oats, peas, and sugarcane leaves, oxidized dihydroxyphenylalanine at a rate of 11 to 120 mumoles x mg(-1) chlorophyll x hr(-1). Polyphenol oxidase in these chloroplasts required a low intensity of red light for activity. Fifty or 75% activation of the oxidase in wheat chloroplasts required 4 to 6 foot candles of light and more light was required for alfalfa chloroplasts. Blue or far red light were ineffective. Trypsin was inhibitory. Upon aging chloroplasts from wheat leaves, but not alfalfa or peas, for 5 to 7 days at 4 C the total polyphenol oxidase activity did not increase, but the activation characteristics changed to those of chloroplasts from the spinach group. Chloroplasts from a third group of plants, including bean, tomato, and corn leaves, slowly oxidized dihydroxyphenylalanine in the dark and exhibited no latency. PMID:16658308

Tolbert, N E

1973-02-01

352

Phenol Oxidase Mediated Protein Cross-Linking.  

National Technical Information Service (NTIS)

This project is examining the mechanisms of protein cross linking induced by phenol oxidase mediated processes in the schistosome eggshell. Synthetic peptides are being used as models for this process. Physical and chemical techniques are being used to ex...

C. R. Middaugh J. S. Cordingley

1988-01-01

353

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.

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

2012-01-01

354

Application of p-toluidine in chromogenic detection of catechol and protocatechuate, diphenolic intermediates in catabolism of aromatic compounds  

SciTech Connect

In the presence of p-toluidine and iron, protocatechuate and catechols yield color. Inclusion of p-toluidine in media facilities the screening of microbial strains for alterations affecting aromatic catabolism. Such strains include mutants affected in the expression of oxygenases and Escherichia coli colonies carrying cloned or subcloned aromatic catabolic genes which encode enzymes giving rise to protocatechuate or catechol. The diphenolic detection system can also be applied to the creation of vectors relying on insertion of cloned DNA into one of the latter marker genes.

Parke, D. (Yale Univ., New Haven, CT (United States))

1992-08-01

355

Phase content, tetragonality, and crystallite size of nanoscaled barium titanate synthesized by the catecholate process: effect of calcination temperature  

Microsoft Academic Search

A modified catecholate process has been applied to synthesize high purity barium titanate powders in the submicron range. A barium titanium-catechol complex, Ba[Ti(C6H4O2)3] was prepared from TiCl4, C6H4(OH)2 and BaCO3, freeze-dried, and calcined for 3 h at temperatures between 600 and 1300 °C. Phase transformation and crystallite size of the calcined powders were investigated as a function of the calcination temperature

Wongduan Maison; Reinhard Kleeberg; Robert B. Heimann; Sukon Phanichphant

2003-01-01

356

Evidence for the existence of PAH-quinone reductase and catechol- O -methyltransferase in Mycobacterium vanbaalenii PYR-1  

Microsoft Academic Search

Polycyclic aromatic hydrocarbon (PAH) quinone reductase (PQR) and catechol- O-methyltransferase (COMT), from the PAH-degrading Mycobacterium vanbaalenii PYR-1, were demonstrated to be constitutive enzymes located in the soluble fraction of cell extracts. PQR activities for the reduction of 9,10-phenanthrenequinone and 4,5-pyrene- quinone were 1.40±0.13 and 0.12±0.01 ?mol min ?1 mg-protein ?1, respectively. The exogenous catechols alizarin, anthrarobin, 2,3-dihydroxynaphthalene and esculetin inhibited PQR activity. Anthrarobin

Yong-Hak Kim; Joanna D. Moody; James P. Freeman; Barbara Brezna; Karl-Heinrich Engesser; Carl E. Cerniglia

2004-01-01

357

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.

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

358

Evidence for biotrophic lifestyle and biocontrol potential of dark septate endophyte Harpophora oryzae to rice blast disease.  

PubMed

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

2013-04-18

359

Polymorphic minisatellites in the mitochondrial DNAs of Oryza and Brassica.  

PubMed

Polymorphic analyses of angiosperm mitochondrial DNA are rare in comparison with chloroplast DNA, because few target sequences in angiosperm mitochondrial DNA are known. Minisatellites, a tandem array of repeated sequences with a repeat unit of 10 to ~100 bp, are popular target sequences of animal mitochondria, but Beta vulgaris is the only known angiosperm species for which such an analysis has been conducted. From this lack of information, it was uncertain as to whether polymorphic minisatellites existed in other angiosperm species. Ten plant mitochondrial DNAs were found to contain minisatellite-like repeated sequences, most of which were located in intergenic regions but a few occurred in gene coding and intronic regions. Oryza and Brassica accessions were selected as models for the investigation of minisatellite polymorphism because substantial systematic information existed. PCR analysis of 42 Oryza accessions revealed length polymorphisms in four of the five minisatellites. The mitochondrial haplotypes of the 16 Oryza accessions with chromosomal complement (genome) types of CC, BBCC and CCDD were identical but were clearly distinguished from BB-genome accessions, a result consistent with the notion that the cytoplasmic donor parent of the amphidiploid species might be the CC-genome species. Twenty-nine accessions of six major cultivated species of Brassica were classified into five mitochondrial haplotypes based on two polymorphic minisatellites out of six loci. The haplotypes of Brassica juncea and Brassica carinata accessions were identical to Brassica rapa and Brassica nigra accessions, respectively. The haplotypes of Brassica napus accessions were heterogeneous and unique, results that were consistent with previous studies. PMID:21562713

Honma, Yujiro; Yoshida, Yu; Terachi, Toru; Toriyama, Kinya; Mikami, Tetsuo; Kubo, Tomohiko

2011-05-12

360

PPAR? and Proline Oxidase in Cancer  

PubMed Central

Proline is metabolized by its own specialized enzymes with their own tissue and subcellular localizations and mechanisms of regulation. The central enzyme in this metabolic system is proline oxidase, a flavin adenine dinucleotide-containing enzyme which is tightly bound to mitochondrial inner membranes. The electrons from proline can be used to generate ATP or can directly reduce oxygen to form superoxide. Although proline may be derived from the diet and biosynthesized endogenously, an important source in the microenvironment is from degradation of extracellular matrix by matrix metalloproteinases. Previous studies showed that proline oxidase is a p53-induced gene and its overexpression can initiate proline-dependent apoptosis by both intrinsic and extrinsic pathways. Another important factor regulating proline oxidase is peroxisome proliferator activated receptor gamma (PPAR?). Importantly, in several cancer cells, proline oxidase may be an important mediator of the PPAR?-stimulated generation of ROS and induction of apoptosis. Knockdown of proline oxidase expression by antisense RNA markedly decreased these PPAR?-stimulated effects. These findings suggest an important role in the proposed antitumor effects of PPAR?. Moreover, it is possible that proline oxidase may contribute to the other metabolic effects of PPAR?.

Phang, James M.; Pandhare, Jui; Zabirnyk, Olga; Liu, Yongmin

2008-01-01

361

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.

2009-01-01

362

[Thermal stability of Penicillium adametzii glucose oxidase].  

PubMed

The thermal stability of glucose oxidase was studied at temperatures between 50 and 70 degrees C by kinetic and spectroscopic (circular dichroism) methods. The stability of glucose oxidase was shown to depend on the medium pH, protein concentration, and the presence of protectors in the solution. At low protein concentrations (< 15 micrograms/ml) and pH > 5.5, the rate constants kin (s-1) for thermal inactivation of glucose oxidase were high. Circular dichroic spectra suggested an essential role of beta structures in stabilizing the protein globule. At a concentration of 15 micrograms protein/ml, the activation energy Ea of thermal inactivation of glucose oxidase in aqueous solution was estimated at 79.1 kcal/mol. Other thermodynamic activation parameters estimated at 60 degrees C had the following values: delta H = 78.4 kcal/mol, delta G = 25.5 kcal/mol, and delta S = 161.9 entropy units. The thermal inactivation of glucose oxidase was inhibited by KCl, polyethylene glycols, and polyols. Among polyols, the best was sorbitol, which stabilized glucose oxidase without affecting its activity. Ethanol, phenol, and citrate exerted destabilizing effects. PMID:11771321

Eremin, A N; Metelitsa, D I; Shishko, Zh F; Mikha?lova, R V; Iasenko, M I; Lobanok, A G

363

Partial characterization of peroxidase and polyphenol oxidase activities in blackberry fruits.  

PubMed

A partial characterization of peroxidase (POD) and polyphenol oxidase (PPO) activities in blackberry fruits is described. Two cultivars of blackberry (Wild and Thornless) were analyzed for POD and PPO activities. Stable and highly active POD and PPO extracts were obtained using insoluble poly(vinylpyrrolidone) and Triton X-100 in 0.05 M sodium phosphate, pH 7.5, buffer. Blackberry POD and PPO activities have a pH optimum of 6.5, in a reaction mixture of 0.2 M sodium phosphate. Optimal POD activity was found with 3% o-dianisidine. Maximum PPO activity was found with catechol (catecholase activity) followed by 4-methylcatechol. Polyacrylamide gel electrophoresis of blackberry extracts under non-denaturing conditions resolved in various bands. In the POD extracts of Wild fruits, there was only one band with a mobility of 0.12. In the Thornless POD extracts there were three well-resolved bands, with R(f) values of 0.63, 0.36, and 0.09. Both the Wild and Thornless blackberry cultivars produced a single band of PPO, with R(f) values of 0.1 for Wild and 0.06 for Thornless. PMID:11087502

González, E M; de Ancos, B; Cano, M P

2000-11-01

364

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

2013-03-17

365

Mechanics of metal-catecholate complexes: The roles of coordination state and metal types.  

PubMed

There have been growing evidences for the critical roles of metal-coordination complexes in defining structural and mechanical properties of unmineralized biological materials, including hardness, toughness, and abrasion resistance. Their dynamic (e.g. pH-responsive, self-healable, reversible) properties inspire promising applications of synthetic materials following this concept. However, mechanics of these coordination crosslinks, which lays the ground for predictive and rational material design, has not yet been well addressed. Here we present a first-principles study of representative coordination complexes between metals and catechols. The results show that these crosslinks offer stiffness and strength near a covalent bond, which strongly depend on the coordination state and type of metals. This dependence is discussed by analyzing the nature of bonding between metals and catechols. The responsive mechanics of metal-coordination is further mapped from the single-molecule level to a networked material. The results presented here provide fundamental understanding and principles for material selection in metal-coordination-based applications. PMID:24107799

Xu, Zhiping

2013-10-10

366

Time-resolved photoelectron imaging of excited state relaxation dynamics in phenol, catechol, resorcinol, and hydroquinone  

NASA Astrophysics Data System (ADS)

Time-resolved photoelectron imaging was used to investigate the dynamical evolution of the initially prepared S1 (??*) excited state of phenol (hydroxybenzene), catechol (1,2-dihydroxybenzene), resorcinol (1,3-dihydroxybenzene), and hydroquinone (1,4-dihydroxybenzene) following excitation at 267 nm. Our analysis was supported by ab initio calculations at the coupled-cluster and CASSCF levels of theory. In all cases, we observe rapid (<1 ps) intramolecular vibrational redistribution on the S1 potential surface. In catechol, the overall S1 state lifetime was observed to be 12.1 ps, which is 1-2 orders of magnitude shorter than in the other three molecules studied. This may be attributed to differences in the H atom tunnelling rate under the barrier formed by a conical intersection between the S1 state and the close lying S2 (??*) state, which is dissociative along the O-H stretching coordinate. Further evidence of this S1/S2 interaction is also seen in the time-dependent anisotropy of the photoelectron angular distributions we have observed. Our data analysis was assisted by a matrix inversion method for processing photoelectron images that is significantly faster than most other previously reported approaches and is extremely quick and easy to implement.

Livingstone, Ruth A.; Thompson, James O. F.; Iljina, Marija; Donaldson, Ross J.; Sussman, Benjamin J.; Paterson, Martin J.; Townsend, Dave

2012-11-01

367

Semiquinone radical intermediate in catecholic estrogen-mediated cytotoxicity and mutagenesis: Chemoprevention strategies with antioxidants  

PubMed Central

Modulation of the cytotoxicity and mutagenicity of 4-hydroxyestradiol (4-OHE2), an oxidative metabolite of estrogen, by antioxidants was assessed in human MCF7 cells and TK-6 lymphoblast cells. The cytotoxicity of the catecholic estrogens was potentiated by depletion of intracellular glutathione and was independent of oxygen concentration. Agents such as the nitroxide Tempol can facilitate the oxidation of the semiquinone to the Q and enhanced 4-OHE2 cytotoxicity. Conversely, reducing agents such as ascorbate, cysteine, and 1,4-dihydroxytetramethylpiperidine (THP) protected against cytotoxicity and decreased mutation induction, presumably by reducing the semiquinone to the hydroquinone. Our results support the proposition that oxidation of the semiquinone to the corresponding Q is crucial in eliciting the deleterious effects of catecholic estrogens. Furthermore, because the deleterious effects of 4-OHE2 were abrogated by dietary and synthetic antioxidants, our results would support the chemopreventive use of diets rich in reducing substances (vitamins and added synthetic antioxidants) as a means of decreasing the risks associated with estrogen exposure and developing of breast cancer.

Samuni, Ayelet M.; Chuang, Eric Y.; Krishna, Murali C.; Stein, William; DeGraff, William; Russo, Angelo; Mitchell, James B.

2003-01-01

368

[Mechanism of the suppressive effect of catechol estrogen on the preovulatory LH surge].  

PubMed

The administration of 100 micrograms 2-hydroxyestrone (2-OHE1) or 2-hydroxyestradiol-17 beta (2-OHE2) at 0900h or 1000h in the morning of proestrus into normal 4-day cycling rats results in suppression of the preovulatory LH surge in the afternoon of that day. The LH-RH content of the median eminence in control rats decreases sharply in the afternoon from elevated noon levels. However, the catechol estrogen-treated rats do not show this decrease. These results indicate that the catecholestrogens block the preovulatory LH surge by preventing the release of LH-RH from the median eminence, but do not interfere with the synthesis and accumulation of LH-RH. Furthermore, injections of non-uterotropic 2-OHE1 twice at 30 minutes intervals into ovariectomized rats fail to affect the LH tonic secretion by 180 minutes after the initial injection. These data indicate that catechol estrogen interferes with the brief neuronal triggering phase necessary for LH-RH release, but does not affect the LH tonic secretion which is an estrogen-independent process. PMID:2828490

Okatani, Y; Sagara, Y

1987-11-01

369

Mechanics of metal-catecholate complexes: The roles of coordination state and metal types  

NASA Astrophysics Data System (ADS)

There have been growing evidences for the critical roles of metal-coordination complexes in defining structural and mechanical properties of unmineralized biological materials, including hardness, toughness, and abrasion resistance. Their dynamic (e.g. pH-responsive, self-healable, reversible) properties inspire promising applications of synthetic materials following this concept. However, mechanics of these coordination crosslinks, which lays the ground for predictive and rational material design, has not yet been well addressed. Here we present a first-principles study of representative coordination complexes between metals and catechols. The results show that these crosslinks offer stiffness and strength near a covalent bond, which strongly depend on the coordination state and type of metals. This dependence is discussed by analyzing the nature of bonding between metals and catechols. The responsive mechanics of metal-coordination is further mapped from the single-molecule level to a networked material. The results presented here provide fundamental understanding and principles for material selection in metal-coordination-based applications.

Xu, Zhiping

2013-10-01

370

Structural and energetic aspects of the protonation of phenol, catechol, resorcinol, and hydroquinone.  

PubMed

The various protonated forms of phenol (1), catechol (2), resorcinol (3), and hydroquinone (4) were explored by ab initio quantum chemical calculations at the MP2/6-31G(d) and B3LYP/6-31G(d) levels. Proton affinities (PA) of 1-4 were calculated by the combined G2(MP2,SVP) method, and their gas-phase basicities were estimated after calculation of the change in entropy on protonation. These theoretical data were compared with the corresponding experimental values determined in a high-pressure mass spectrometer. This comparison confirmed that phenols are essentially carbon bases and that protonation generally occurs in a position para to the hydroxyl group. Resorcinol is the most effective base (PA = 856 kJ mol-1) due to the participation of both oxygen atoms in the stabilization of the protonated form. Since protonation is accompanied by a freezing of the two internal rotations, a significant decrease in entropy is observed. The basicity of catechol (PA = 823 kJ mol-1) is due to the existence of an intramolecular hydrogen bond, which is strengthened upon protonation. The lower basicity of hydroquinone (PA = 808 kJ mol-1) is a consequence of the fact that protonation necessarily occurs in a position ortho to the hydroxyl group. When the previously published data are reconsidered and a corrected protonation entropy is used, a proton affinity value of 820 kJ mol-1 is obtained for phenol. PMID:12489218

Bouchoux, Guy; Defaye, Dirk; McMahon, Terrance; Likholyot, Alexander; Mó, Otilia; Yáńez, Manuel

2002-07-01

371

Improvement of the electrochemical detection of catechol by the use of a carbon nanotube based biosensor.  

PubMed

Tyrosinase (Tyr) has been used frequently for the detection of phenolic compounds. The development of a biosensor based on this enzyme-integrated carbon nanotube (CNT) epoxy composite electrode (CNTECE) is described in order to perform measurements of catechol. The enzyme is immobilized into a matrix prepared by dispersion of multi-wall CNT (MWCNT) inside the epoxy resin forming a CNT epoxy-biocomposite (CNTEC-Tyr). The use of CNT improves the electronic transference between the enzyme and the electrode surface. The modified electrode was characterized electrochemically by amperometric and voltammetric techniques. An applied potential of -200 mV vs. Ag/AgC1 applied to the biocomposite based electrode was found to be optimal for electrochemical reduction of the enzymatic reaction products (quinones). The biosensor modified with MWCNT is also compared with a tyrosinase biosensor based on a graphite epoxy-composite (GECE-Tyr) showing a sensitivity of 294 microA/mM cm(2), a detection limit of 0.01 mM for a signal-to-noise ratio of 3 in a concentration range of 0.0-0.15 mM catechol with a response time of 20 s and an RSD of 8% (n = 3). The electrodes were stable for more than 24 h. A 90% increase of the signal indicated that the response is better with the biocomposite based on carbon nanotubes rather than with the graphite. PMID:19082175

Pérez López, B; Merkoçi, A

2008-10-18

372

Suicide Inactivation of Catechol 2,3-Dioxygenase from Pseudomonas putida mt-2 by 3-Halocatechols  

PubMed Central

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 (K2) were 1.62 × 10?3 sec?1 for 3-chlorocatechol and 2.38 × 10?3 sec?1 for 3-fluorocatechol. The inhibitor constants (Ki) were 23 ?M for 3-chlorocatechol and 17 ?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-diendioic acid was formed from 3-chlorocatechol, suggesting 5-chloroformyl-2-hydroxypenta-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-dienoic 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.

Bartels, Iris; Knackmuss, Hans-Joachim; Reineke, Walter

1984-01-01

373

In vitro evaluation of Ro 09-1227, a novel catechol-substituted cephalosporin.  

PubMed Central

Ro 09-1227 is a novel 7-position catechol-substituted parenteral cephalosporin that also has a 3-position radical similar to previously described cephems. The Ro 09-1227 spectrum was slightly wider than that of ceftazidime against members of the family Enterobacteriaceae tested, principally because of greater activity against species producing Richmond-Sykes type I beta-lactamases. Ro 09-1227 was also more active than ceftazidime against some strains producing extended-spectrum plasmid-encoded beta-lactamases, such as TEM-3, -4, -5, -6, -7, and -9, SHV-2 and -3, and CAZ-2. Most strains of Pseudomonas aeruginosa, Xanthomonas maltophilia, and Acinetobacter spp. were also more susceptible to Ro 09-1227 than cefotaxime, ceftriaxone, cefoperazone, and ceftazidime. Haemophilus influenzae (MIC for 90% of strains tested [MIC90], 0.5 micrograms/ml), Neisseria gonorrhoeae (MIC90, 0.015 micrograms/ml), and Moraxella (Branhamella) catarrhalis (MIC90, 0.5 micrograms/ml) were also Ro 09-1227 susceptible. Ro 09-1227 activity against important gram-positive cocci was most comparable to that of ceftazidime. Bacteroides fragilis (MIC90, greater than 32 micrograms/ml) and the enterococci (MIC90, greater than 32 micrograms/ml) were resistant to Ro 09-1227. These in vitro results indicate that this catechol-substituted cephalosporin may be useful as an empiric agent, especially for some isolates resistant to currently available broad-spectrum cephalosporins.

Jones, R N; Erwin, M E

1992-01-01

374

Mechanics of metal-catecholate complexes: The roles of coordination state and metal types  

PubMed Central

There have been growing evidences for the critical roles of metal-coordination complexes in defining structural and mechanical properties of unmineralized biological materials, including hardness, toughness, and abrasion resistance. Their dynamic (e.g. pH-responsive, self-healable, reversible) properties inspire promising applications of synthetic materials following this concept. However, mechanics of these coordination crosslinks, which lays the ground for predictive and rational material design, has not yet been well addressed. Here we present a first-principles study of representative coordination complexes between metals and catechols. The results show that these crosslinks offer stiffness and strength near a covalent bond, which strongly depend on the coordination state and type of metals. This dependence is discussed by analyzing the nature of bonding between metals and catechols. The responsive mechanics of metal-coordination is further mapped from the single-molecule level to a networked material. The results presented here provide fundamental understanding and principles for material selection in metal-coordination-based applications.

Xu, Zhiping

2013-01-01

375

Inhibition of rodent brain monoamine oxidase and tyrosine hydroxylase by endogenous compounds - 1,2,3,4-tetrahydro-isoquinoline alkaloids.  

PubMed

Four different noncatecholic and one catecholic tetrahydroisoquinolines (TIQs), cyclic condensation derivatives of beta-phenylethylamine and dopamine with aldehydes or keto acids, were examined for the inhibition of rat and mouse brain monoamine oxidase (MAO) and rat striatum tyrosine hydroxylase (TH) activity. Simple noncatecholic TIQs were found to act as moderate (TIQ, N-methyl-TIQ, 1-methyl-TIQ) or weak (1-benzyl-TIQ), MAO B and MAO A inhibitors. 1-Methyl-TIQ inhibited more potently MAO-A than MAO-B; the similar but more modest effect was exerted by salsolinol. Only salsolinol markedly inhibited TH activity, being competitive with the enzyme biopterin cofactor. The inhibition of MAO and TH by TIQs is discussed in relation to their ability to regulate monoamine metabolism. PMID:15662085

Patsenka, Antoni; Antkiewicz-Michaluk, Lucyna

376

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.

Schramm, Agata; Matusik, Pawel; Osmenda, Grzegorz; Guzik, Tomasz J

2012-01-01

377

Light regulation of asexual development in the rice blast fungus, Magnaporthe oryzae.  

PubMed

Light is a major environmental factor that influences many biological processes. We characterized the roles of light in asexual development (including the formation of aerial hyphae and conidiophore) in Magnaporthe oryzae, which is the causal agent of rice blast disease. Our data revealed a complex nature of light regulation in the asexual developments of M. oryzae. Asexual development of M. oryzae is suppressed by blue light in a light/dark cycling environment and asexual spore release is controlled by both blue and red light. We demonstrated that even very dim light, about 10 micromol m(-2), is sufficient to suppress spore-release behavior in M. oryzae. We also generated knockout strains of a blue light receptor, mgwc-1, the M. oryzae homolog of white collar-1 in Neurospora crassa, and demonstrated blue-light-specific regulation in the asexual development and spore release in M. oryzae. Our findings in this agriculturally important pathogen, M. oryzae, broaden our understanding of the roles of light in fungal development. PMID:16765070

Lee, Kwangwon; Singh, Pratibha; Chung, Wen-Chuan; Ash, Joshua; Kim, Tae Sung; Hang, Lisa; Park, Sohyun

2006-06-09

378

Adipogenesis-related increase of semicarbazide-sensitive amine oxidase and monoamine oxidase in human adipocytes  

Microsoft Academic Search

A strong induction of semicarbazide-sensitive amine oxidase (SSAO) has previously been reported during murine preadipocyte lineage differentiation but it remains unknown whether this emergence also occurs during adipogenesis in man. Our aim was to compare SSAO and monoamine oxidase (MAO) expression during in vitro differentiation of human preadipocytes and in adipose and stroma-vascular fractions of human fat depots. A human

Sandy Bour; Daničle Daviaud; Sandra Gres; Corinne Lefort; Danielle Prévot; Antonio Zorzano; Martin Wabitsch; Jean-Sébastien Saulnier-Blache; Philippe Valet; Christian Carpéné

2007-01-01

379

The molybdoenzymes xanthine oxidase and aldehyde oxidase contain fast- and slow-DTNB reacting sulphydryl groups  

Microsoft Academic Search

The reactivities with an excess of 5-5'-dithiobis (2-nitrobenzoic) acid (DTNB) of sulphydryl residues present in xanthine oxidase and aldehyde oxidase were studied and compared. The results show that two classes of sulphydryl groups with quite different reactivities exist in both enzymes either native or denatured. Some of the available sulphydryl residues thus react instantaneously with the DTNB, whereas the others

Francesc Cabré; Marta Cascante; Enric I. Canela

1992-01-01

380

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)

1996-11-01

381

Plasmids for expression of heterologous proteins in Rhizopus oryzae.  

PubMed

Rhizopus oryzae has long been used for enzyme production (e.g., glucoamylase and lipase), organic acid synthesis, and various fermented food applications. In this work, we describe a set of plasmid-based expression vectors that can be used for the production of heterologous proteins in R. oryzae. Three plasmid vectors have been created using either the glucoamylase A (amyA), pyruvate decarboxylase (pdcA), or phosphoglycerate kinase (pgk1) promoters to drive expression of heterologous proteins. All three plasmids use the pdcA terminator for transcription termination, the pyrG gene for restoration of uracil prototrophy, and an ampicillin resistance gene and origin of replication for maintenance in Escherichia coli. We have expressed green fluorescent protein (GFP) and compared transcription and protein accumulation for each of the expression vectors. Accumulation of GFP transcript and protein was directly correlated with the choice of promoter with pdcA > amyA > pgk1. Transcript level appears to parallel GFP protein accumulation. Plasmid copy number had little impact on transcription or protein accumulation. These vectors should be useful for overexpression of heterologous proteins and potentially, metabolic engineering of Rhizopus strains. PMID:16804680

Mertens, Jeffrey A; Skory, Christopher D; Ibrahim, Ashraf S

2006-06-28

382

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.

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

2013-01-01

383

Catechol-O-Methyltransferase (COMT) Val108\\/158 Met polymorphism does not modulate executive function in children with ADHD  

Microsoft Academic Search

BACKGROUND: An association has been observed between the catechol-O-methyltransferase (COMT) gene, the predominant means of catecholamine catabolism within the prefrontal cortex (PFC), and neuropsychological task performance in healthy and schizophrenic adults. Since several of the cognitive functions typically deficient in children with Attention Deficit Hyperactivity Disorder (ADHD) are mediated by prefrontal dopamine (DA) mechanisms, we investigated the relationship between a

Evan Taerk; Natalie Grizenko; Leila Ben Amor; Philippe Lageix; Valentin Mbekou; Rosherie Deguzman; Adam Torkaman-Zehi; Marina Ter Stepanian; Chantal Baron; Ridha Joober

2004-01-01

384

The Key Role of Chlorocatechol 1,2-Dioxygenase in Phytoremoval and Degradation of Catechol by Transgenic Arabidopsis1[W  

PubMed Central

Transgenic exploitation of bacterial degradative genes in plants has been considered a favorable strategy for degrading organic pollutants in the environment. The aromatic ring characteristic of these pollutants is mainly responsible for their recalcitrance to degradation. In this study, a Plesiomonas-derived chlorocatechol 1,2-dioxygenase (TfdC) gene (tfdC), capable of cleaving the aromatic ring, was introduced into Arabidopsis (Arabidopsis thaliana). Morphology and growth of transgenic plants are indistinguishable from those of wild-type plants. In contrast, they show significantly enhanced tolerances to catechol. Transgenic plants also exhibit strikingly higher capabilities of removing catechol from their media and high efficiencies of converting catechol to cis,cis-muconic acid. As far-less-than-calculated amounts of cis,cis-muconic acid were accumulated within the transgenic plants, existence of endogenous TfdD- and TfdE-like activities was postulated and, subsequently, putative orthologs of bacterial tfdD and tfdE were detected in Arabidopsis. However, no TfdC activity and no putative orthologs of either tfdC or tfdF were identified. This work indicates that the TfdC activity, conferred by tfdC in transgenic Arabidopsis, is a key requirement for phytoremoval and degradation of catechol, and also suggests that microbial degradative genes may be transgenically exploited in plants for bioremediation of aromatic pollutants in the environment.

Liao, Yang; Zhou, Xiao; Yu, Jin; Cao, Yajun; Li, Xian; Kuai, Benke

2006-01-01

385

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...

386

Affect-Modulated Startle: Interactive Influence of Catechol-O-Methyltransferase Val158Met Genotype and Childhood Trauma  

Microsoft Academic Search

The etiology of emotion-related disorders such as anxiety or affective disorders is considered to be complex with an interaction of biological and environmental factors. Particular evidence has accumulated for alterations in the dopaminergic and noradrenergic system – partly conferred by catechol-O-methyltransferase (COMT) gene variation – for the adenosinergic system as well as for early life trauma to constitute risk factors

Benedikt Klauke; Bernward Winter; Agnes Gajewska; Peter Zwanzger; Andreas Reif; Martin J. Herrmann; Andrea Dlugos; Bodo Warrings; Christian Jacob; Andreas Mühlberger; Volker Arolt; Paul Pauli; Jürgen Deckert; Katharina Domschke

2012-01-01

387

Comparative studies of enhanced iron-mediated production of hydroxyl radical by glutathione, cysteine, ascorbic acid, and selected catechols  

Microsoft Academic Search

A sensitive electrochemical detection system was employed together with a specific salicylate hydroxylation assay to comparatively assess the effects of various substances on the iron-mediated generation of the hydroxyl radical (·OH). Hydroxyl radical production was found to be enhanced significantly by reduced glutathione, cysteine, ascorbic acid, and selected catechols, but not by mannitol, melatonin or tyramine. The data showed that

Anthony J. Nappi; Emily Vass

1997-01-01

388

RATE AND CAPACITY OF HEPATIC MICROSOMAL RING HYDROXYLATION OF PHENOL TO HYDROQUINONE AND CATECHOL IN RAINBOW TROUT  

EPA Science Inventory

Rainbow trout (Oncorhynchus mykiss) liver microsomes were used to study the rate of ring-hydroxylation of phenol PH) by directly measuring the production of hydroquinone (HQ), the primary metabolite, and catechol (CAT), a secondary metabolite. An HPLC method with integrated ultra...

389

RATE AND CAPACITY OF HEPATIC MICROSOMAL RING HYDROXYLATION OF PHENOL TO HYDROQUINONE AND CATECHOL IN RAINBOW TROUT (ONCORHYNCHUS MYKISS)  

EPA Science Inventory

Rainbow trout liver microsomes were used to study the rate of ring-hydroxylation of phenol (PH) by directly measuring the production of hydroquinone (HQ), the primary metabolite, and catechol (CAT), a secondary metabolite. An HPLC method with integrated ultroviolet (UV) and elect...

390

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

391

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.

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

1992-01-01

392

Coupled redox transformations of catechol and cerium at the surface of a cerium(III) phosphate mineral  

NASA Astrophysics Data System (ADS)

Highly insoluble Ce-bearing phosphate minerals form by weathering of apatite [Ca 5(PO 4) 3.(OH,F,Cl)], and are important phosphorous repositories in soils. Although these phases can be dissolved via biologically-mediated pathways, the dissolution mechanisms are poorly understood. In this paper we report spectroscopic evidence to support coupling of redox transformations of organic carbon and cerium during the reaction of rhabdophane (CePO 4·H 2O) and catechol, a ubiquitous biogenic compound, at pH 5. Results show that the oxic-anoxic conditions influence the mineral dissolution behavior. Under anoxic conditions, the release of P and Ce occurs stoichiometrically. In contrast, under oxic conditions, the mineral dissolution behavior is incongruent, with dissolving Ce 3+ ions oxidizing to CeO 2. Reaction product analysis shows the formation of CO 2, polymeric C, and oxalate and malate. The presence of more complex forms of organic carbon was also confirmed. Near edge X-ray absorption fine structure spectroscopy measurements at Ce-M 4,5 and C-K absorption edges on reacted CePO 4·H 2O samples in the absence or presence of catechol and dissolved oxygen confirm that (1) the mineral surface converts to the oxide during this reaction, while full oxidation is limited to the near-surface region only; (2) the Ce valence remains unchanged when the reaction between CePO 4·H 2O and O 2 but in the absence of catechol. Carbon K-edge spectra acquired from rhabdophane reacted with catechol under oxic conditions show spectral features before and after reaction that are considerably different from catechol, indicating the formation of more complex organic molecules. Decreases in intensity of characteristic catechol peaks are accompanied by the appearance of new ? ? resonances due to carbon in carboxyl (ca. 288.5 eV) and carbonyl (ca. 289.3 eV) groups, and the development of broad structure in the ? ? region characteristic of aliphatic carbon. Evolution of the C K-edge spectra is consistent with aromatic-ring cleavage and polymerization. These results further substantiate that the presence of catechol, O 2 (aq) causes both the oxidation of structural Ce 3+ and the transformation of catechol to more complex organic molecules. Scanning Transmission X-Ray Microscopy measurements at the C K and Ce M 4,5 edges indicate three dominant organic species, varying in complexity and association with the inorganic phase. Untransformed catechol is loosely associated with CeO 2, whereas more complex organic molecules that exhibit lower aromaticity and stronger C dbnd O ? ? resonances of carboxyl-C and carbonyl-C groups are only found in association with the grains. These results further serve as basis to postulate that, in the presence of O 2, CeO 2 can mediate the oxidative polymerization of catechol to form higher molecular weight polymers. The present work provides evidence for a pathway of biologically-induced, non-enzymatic oxidation of cerium and formation of small CeO 2 particles at room temperature. These findings may have implications for carbon cycling in natural and cerium-contaminated soils and aqueous environments.

Cervini-Silva, Javiera; Gilbert, Benjamin; Fakra, Sirine; Friedlich, Stephan; Banfield, Jillian

2008-05-01

393

The composition of milk xanthine oxidase  

PubMed Central

The composition of milk xanthine oxidase has been reinvestigated. When the enzyme is prepared by methods that include a selective denaturation step in the presence of sodium salicylate the product is obtained very conveniently and in high yield, and is homogeneous in the ultracentrifuge and in recycling gel filtration. It has specific activity higher than previously reported preparations of the enzyme and its composition approximates closely to 2mol of FAD, 2g-atoms of Mo and 8g-atoms of Fe/mol of protein (molecular weight about 275000). In contrast, when purely conventional preparative methods are used the product is also homogeneous by the above criteria but has a lower specific activity and is generally comparable to the crystallized enzyme described previously. Such samples also contain 2mol of FAD/mol of protein but they have lower contents of Mo (e.g. 1.2g-atom/mol). Amino acid compositions for the two types of preparation are indistinguishable. These results confirm the previous conclusion that conventional methods give mixtures of xanthine oxidase with an inactive modification of the enzyme now termed `de-molybdo-xanthine oxidase', and show that salicylate can selectively denature the latter. The origin of de-molybdo-xanthine oxidase was investigated. FAD/Mo ratios show that it is present not only in enzyme purified by conventional methods but also in `milk microsomes' (Bailie & Morton, 1958) and in enzyme samples prepared without proteolytic digestion. We conclude that it is secreted by cows together with the active enzyme and we discuss its occurrence in the preparations of other workers. Studies on the milks of individual cows show that nutritional rather than genetic factors determine the relative amounts of xanthine oxidase and de-molybdo-xanthine oxidase. A second inactive modification of the enzyme, now termed `inactivated xanthine oxidase', causes variability in activity relative to E450 or to Mo content and formation of it decreases these ratios during storage of enzyme samples including samples free from demolybdo-xanthine oxidase. We conclude that even the best purified xanthine oxidase samples described here and by other workers are contaminated by significant amounts of the inactivated form. This may complicate the interpretation of changes in the enzyme taking place during the slow phase of reduction by substrates. Attempts to remove iron from the enzyme by published methods were not successful. ImagesFig. 2.

Hart, L. I.; McGartoll, Mary A.; Chapman, Helen R.; Bray, R. C.

1970-01-01

394

NADPH oxidases in cardiovascular health and disease.  

PubMed

Increased oxidative stress plays an important role in the pathophysiology of cardiovascular diseases such as hypertension, atherosclerosis, diabetes, cardiac hypertrophy, heart failure, and ischemia-reperfusion. Although several sources of reactive oxygen species (ROS) may be involved, a family of NADPH oxidases appears to be especially important for redox signaling and may be amenable to specific therapeutic targeting. These include the prototypic Nox2 isoform-based NADPH oxidase, which was first characterized in neutrophils, as well as other NADPH oxidases such as Nox1 and Nox4. These Nox isoforms are expressed in a cell- and tissue-specific fashion, are subject to independent activation and regulation, and may subserve distinct functions. This article reviews the potential roles of NADPH oxidases in both cardiovascular physiological processes (such as the regulation of vascular tone and oxygen sensing) and pathophysiological processes such as endothelial dysfunction, inflammation, hypertrophy, apoptosis, migration, angiogenesis, and vascular and cardiac remodeling. The complexity of regulation of NADPH oxidases in these conditions may provide the possibility of targeted therapeutic manipulation in a cell-, tissue- and/or pathway-specific manner at appropriate points in the disease process. PMID:16771662

Cave, Alison C; Brewer, Alison C; Narayanapanicker, Anilkumar; Ray, Robin; Grieve, David J; Walker, Simon; Shah, Ajay M

395

Conformational studies of Escherichia coli pyruvate oxidase.  

PubMed

Pyruvate oxidase (pyruvate:oxygen oxidoreductase (phosphorylating), EC 1.2.3.3) is a peripheral membrane enzyme from Escherichia coli which utilizes the cofactors thiamin pyrophosphate (TPP) and flavin-adenine dinucleotide (FAD) to catalyze the decarboxylation of pyruvate to acetic acid and carbon dioxide. The specific activity of the oxidase is enhanced 25-fold when assayed in the presence of certain lipids and detergents. Previous studies have demonstrated that the affinity of pyruvate oxidase for phospholipids and detergents is substantially increased when the flavin is reduced. In this paper, several techniques are utilized to probe both the nature of the active site and the conformational changes in the protein which are concomitant with flavin reduction and with the binding of lipids to the enzyme. Analysis of the circular dichroism spectrum in the far ultraviolet region indicates that neither the binding of lipid activators to the oxidase nor reduction of the enzyme-bound flavin by pyruvate has a significant effect on the average secondary structure of the enzyme. High-resolution electron microscopy demonstrates that at low enzyme concentrations, i.e., assay conditions, incubation of the reduced flavoprotein in the presence of an amphiphilic activator does not alter the quaternary structure of pyruvate oxidase. The results indicate that the conformational changes in the protein due either to reduction of the flavin or to the binding of lipid activators are localized. PMID:6751398

O'Brien, T A; Shelton, E; Mather, M; Gennis, R B

1982-08-10

396

Mitochondrial targeting of human protoporphyrinogen oxidase.  

PubMed

Variegate porphyria is an autosomal dominant disorder of heme metabolism resulting from a deficiency in protoporphyrinogen oxidase, an enzyme located on the inner mitochondrial membrane. This study examined the effect of three South African VP-causing mutations (H20P, R59W, R168C) on mitochondrial targeting. Only H20P did not target, and of eight protoporphyrinogen oxidase-GFP chimeric fusion proteins created, N-terminal residues 1-17 were found to be the minimal protoporphyrinogen oxidase sequence required for efficient mitochondrial targeting. Removal of this N-terminal sequence displayed mitochondrial localization, suggesting internal mitochondrial targeting signals. In addition, six constructs were engineered to assess the effect of charge and helicity on mitochondrial targeting of the protein. Of those engineered, only the PPOX20/H20P-GFP construct abolished mitochondrial targeting, presumably through disruption of the protoporphyrinogen oxidase alpha-helix. Based on our results we propose a mechanism for protoporphyrinogen oxidase targeting to the mitochondrion. PMID:16621625

Davids, Lester M; Corrigall, Anne V; Meissner, Peter N

2006-03-06

397

An H-NS-like protein involved in the negative regulation of hrp genes in Xanthomonas oryzae pv. oryzae.  

PubMed

hrp genes encode components of a type III secretion (T3S) system and play crucial roles in the pathogenicity of the rice pathogen Xanthomonas oryzae pv. oryzae (Xoo). A histone-like nucleoid-structuring (H-NS) protein binds DNA and acts as a global transcriptional repressor. Here, we investigated the involvement of an h-ns-like gene, named xrvB, in the expression of hrp genes in Xoo. Under the hrp-inducing culture condition, the expression of a key hrp regulator HrpG increased in the XrvB mutant, followed by activation of the downstream gene expression. Also, in planta, the secretion of a T3S protein (XopR) was activated by the mutation in xrvB. Gel retardation assay indicated that XrvB has DNA-binding activity, but without a preference for the promoter region of hrpG. The results suggest that XrvB negatively regulates hrp gene expression and that an unknown factor(s) mediates the regulation of hrpG expression by XrvB. PMID:21410511

Kametani-Ikawa, Yumi; Tsuge, Seiji; Furutani, Ayako; Ochiai, Hirokazu

2011-03-31

398

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.

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

2013-01-01

399

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

PubMed Central

Rice straw is always regarded as a by-product of rice production, but it could be a significant energy source for ruminant animals. Knowledge of the genetic variation and genetic architecture of cell wall traits will facilitate rice breeders by improving relevant traits through selective breeding and genetic engineering. The common wild rice, Oryza rufipogon Griff., which is considered to be the progenitor of Oryza sativa, has been widely utilized for the identification of genes of agronomic importance for rice genetic improvement. In the present study, the mapping of quantitative trait loci (QTLs) for acid detergent fiber (ADF), neutral detergent fiber (NDF), acid detergent lignin (ADL), and ADL/NDF ratio was carried out in two environments using a backcrossed inbred line (BIL) population derived from a cross between the recurrent parent Xieqingzao B (XB) and an accession of Dongxiang wild rice (DWR). The results indicated that all four traits tested were continuously distributed among the BILs, but many BILs showed transgressive segregation. A total of 16 QTLs were identified for the four traits, but no QTLs were in common in two environments, suggesting that environment has dramatic effects on fiber and lignin syntheses. Compared to the QTL positions for grain yield-related traits, there were no unfavorable correlations between grain yield components and cell wall traits in this population. The QTLs identified in this study are useful for the development of dual-purpose rice varieties that are high in grain yield and are also high in straw quality.

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

2011-01-01

400

Five phylogenetically close rice SWEET genes confer TAL effector-mediated susceptibility to Xanthomonas oryzae pv. oryzae.  

PubMed

Bacterial plant-pathogenic Xanthomonas strains translocate transcription activator-like (TAL) effectors into plant cells to function as specific transcription factors. Only a few plant target genes of TAL effectors have been identified, so far. Three plant SWEET genes encoding putative sugar transporters are known to be induced by TAL effectors from rice-pathogenic Xanthomonas oryzae pv. oryzae (Xoo). We predict and validate that expression of OsSWEET14 is induced by a novel TAL effector, Tal5, from an African Xoo strain. Artificial TAL effectors (ArtTALs) were constructed to individually target 20 SWEET orthologs in rice. They were used as designer virulence factors to study which rice SWEET genes can support Xoo virulence. The Tal5 target box differs from those of the already known TAL effectors TalC, AvrXa7 and PthXo3, which also induce expression of OsSWEET14, suggesting evolutionary convergence on key targets. ArtTALs efficiently complemented an Xoo talC mutant, demonstrating that specific induction of OsSWEET14 is the key target of TalC. ArtTALs that specifically target individual members of the rice SWEET family revealed three known and two novel SWEET genes to support bacterial virulence. Our results demonstrate that five phylogenetically close SWEET proteins, which presumably act as sucrose transporters, can support Xoo virulence. PMID:23879865

Streubel, Jana; Pesce, Céline; Hutin, Mathilde; Koebnik, Ralf; Boch, Jens; Szurek, Boris

2013-07-24

401

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

402

Gene cloning and heterologous expression of pyranose 2-oxidase ...  

Treesearch

Description: A pyranose 2-oxidase gene from the brown-rot basidiomycete ... in Escherichia coli yielding 15 U enzyme activity per ml of induced culture. ... pyranose 2-oxidase, wood-decaying fungi, fungi, biotechnology, industrial applications, ...

403

Generating disulfides with the quiescin sulfhydryl oxidases  

PubMed Central

The Quiescin-sulfhydryl oxidase (QSOX) family of flavoenzymes catalyzes the direct and facile insertion of disulfide bonds into unfolded reduced proteins with concomitant reduction of oxygen to hydrogen peroxide. This review discusses the chemical mechanism of these enzymes and the involvement of thioredoxin and flavin-binding domains in catalysis. The variability of CxxC motifs in the QSOX family is highlighted and attention is drawn to the steric factors that may promote efficient thiol/disulfide exchange during oxidative protein folding. The varied cellular location of these multi-domain sulfhydryl oxidases is reviewed and potential intracellular and extracellular roles are summarized. Finally, this review identifies important unresolved questions concerning this ancient family of sulfhydryl oxidases.

Heckler, Erin J.; Rancy, Pumtiwitt C.; Kodali, Vamsi K.; Thorpe, Colin

2008-01-01

404

Effect of naphthalene on cytochrome oxidase activity  

SciTech Connect

Previous reports have demonstrated that naphthalene inhibits oxygen consumption in Daphnia magna tissue culture cells, and intact mitochondria and submitochondrial particles. These studies were extended to algal mitochondrial respiration as well as photosynthetic activity. The authors were able to demonstrate the specific site of apparent respiratory inhibition to be coenzyme Q (ubiquinone, UQ) and later to demonstrate the molecular basis of this inhibition at ubiquinone. The authors previously could not demonstrate an effect of naphthalene on cytochrome oxidase activity. However, the observation that naphthalene can stimulate respiration in algae prompted the reinvestigation of the effect of naphthalene on the kinetics of cytochrome oxidase. Cytochrome oxidase is a multi-subunit membranous protein responsible for the oxidation of cytochrome c and the reduction of molecular oxygen to water. Because of the complicated nature and mechanism of this enzyme, the potential exists for multiple and possibly opposite effects of naphthalene on its function.

Harmon, H.J.

1988-01-01

405

Copper(II) complexes of a new N-picolylated bis benzimidazolyl diamide ligand: Synthesis, crystal structure and catechol oxidase studies  

Microsoft Academic Search

Copper(II) complexes of a new bis benzimidazole diamide ligand N-picolyl-N,N?-bis(2-methylbenzimidazolyl)hexanediamide [Pic-GBHA=L2] have been synthesized and characterized. One of the compound [Cu(L2)(NO3)2] has been structurally characterized. The copper atom is bound to two benzimidazolyl nitrogen atoms, two amide carbonyl oxygen atoms and a bidentate nitrate ion, resulting in a distorted octahedral geometry. EPR spectra obtained at low temperature indicate a tetragonal

Ruchi Bakshi; Miriam Rossi; Francesco Caruso; Pavan Mathur

2011-01-01

406

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)2·2H2O] (1), [Cu2L2(N3)2·2H2O] (2), [Cu2L3(N3)2·2H2O] (3), [Cu2L4(N3)2·2H2O] (4) and [Cu2L5(N3)2·2H2O] (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

407

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

408

Effect of hydrothermal processing on antioxidant contents and capacities in pigmented rice (Oryza sativa L.)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Purple and red bran rice cultivars (Oryza sativa L.) are rich sources of antioxidants including lipophilic antioxidants (vitamin E homologues and '-oryzanol), soluble phenolics (including anthocyanidins and proanthocyanidins), and cell-wall-bound phenolics. This study investigated impacts of hydroth...

409

Analysis of the Temporal Variation of Radiation Balance Components in Arid Rice (Oryza Sativa L.) Culture.  

National Technical Information Service (NTIS)

The time variation of measured radiation balance components in a cultived rice area (Oryza sativa L.) under arid conditions in the Brazil central-west region was analysed. The relation between global solar radiation, radiation balance, reflected radiation...

J. E. Prates D. T. Coelho S. Steinmetz

1988-01-01

410

Efficient and selective microbial esterification with dry mycelium of Rhizopus oryzae.  

PubMed

The use of dry mycelium of Rhizopus oryzae as biocatalyst for ester production in organic solvent has been studied. Mycelia with notable carboxylesterase activity were produced when different Tweens (20, 40, 60 and 80) were employed as main carbon source for the growth. Dry mycelium of four strains of Rhizopus oryzae proved effective for efficiently catalysing the synthesis of different flavour esters (hexylacetate and butyrate, geranylacetate and butyrate) starting from the corresponding alcohol and free acid, including acetic acid. The esterification of the racemic mixture of 2-octanol and butyric acid proceeded with high enantioselectivity (R-ester produced with enantiomeric excess > or =97%) when Rhizopus oryzae CBS 112.07 and Rhizopus oryzae CBS 260.28 were employed. PMID:11604169

Gandolfi, R; Converti, A; Pirozzi, D; Molinari, F

2001-12-14

411

A radioenzymatic assay of catechol-O-methyltransferase in hair root cells: comparison with erythrocyte activity.  

PubMed

A sensitive radioenzymatic assay of catechol-O-methyltransferase (COMT) in hair root cells is presented. Only five hair roots with intact bulb and sheath are needed for one assay. By pulling 15-20 hairs, 3-4 parallel assays can be performed. As in erythrocytes the COMT activity in hair root cells is constant for each individual. Nevertheless, there is no high correlation between the enzyme activities in erythrocyte and in hair root cells (r = 0.26, 0.1 greater than P greater than 0.05, N = 46). The determination of COMT in hair root cells offers a further application of this source in genetic research, as in the study of a correlation between COMT activity and various endogenous psychiatric disorders. PMID:7228028

Hoo, J J; Strohmeyer, T; Beckermann, W J; Agarwal, D P; Goedde, H W

1981-01-01

412

Synthesis and metal binding properties of salicylate-, catecholate-, and hydroxypyridinonate-functionalized dendrimers.  

PubMed

The synthesis, characterization, and metal-binding studies of chelate-functionalized dendrimers is reported. Salicylate, catecholate, and hydroxypyridinonate bidentate chelators have been coupled to the surface of both poly(propyleneimine) (Astramol) and poly(amidoamine) (Starburst, PAMAM) dendrimers up to the fifth generation (64 endgroups). A general method has been developed for the facile and high quality chromatographic purification of poly(propyleneimine) and poly(amidoamine) dendrimer derivatives. One- and two-dimensional (TOCSY) 1H NMR experiments and electrospray ionization mass spectrometry (ESI-MS) have confirmed the exhaustive coupling of these chelators to the primary amine functionalities of the dendrimers. Spectrophotometric titrations were used to investigate the metal binding ability of these macrochelates. Spectral analysis shows that ferric iron binding to these ligands is localized to the chelating endgroups. The ability of these dendritic polymers to bind large numbers of metal ions may lead to applications as metal sequestering agents for waste remediation technologies. PMID:11205020

Cohen, S M; Petoud, S; Raymond, K N

2001-01-01

413

Association of the Catechol-o-Methyltransferase Gene Polymorphisms with Korean Autism Spectrum Disorders  

PubMed Central

This study evaluated the family-based genetic association between autism spectrum disorders (ASDs) and 5 single-nucleotide polymorphisms (SNPs) in the catechol-o-methyltransferase gene (COMT), which was found among 151 Korean ASDs family trios (dominant model Z = 2.598, P = 0.009, PFDR = 0.045). We found a statistically significant allele transmission or association in terms of the rs6269 SNP in the ASDs trios. Moreover, in the haplotype analysis, the haplotypes with rs6269 demonstrated significant evidence of an association with ASDs (additive model rs6269-rs4818-rs4680-rs769224 haplotype P = 0.004, PFDR = 0.040). Thus, an association may exist between the variants of the COMT gene and the occurrence of ASDs in Koreans.

Yoo, Hee Jeong; Cho, In Hee; Park, Mira; Yang, So Young

2013-01-01

414

Catechol-o-methyltransferase genotype modulates opioid release in decision circuitry.  

PubMed

Impulsivity, a risk factor for substance abuse disorders, is modulated by the Val158 variant of the catechol-O-methyltransferase (COMT) gene. Rodent studies have shown that opioids enhance impulsivity. Furthermore, alcohol consumption leads to endogenous opioid release in the cortex and nucleus accumbens (NAc), and this opioid release is correlated with greater positive hedonic effect. Using the selective mu opioid receptor radioligand [(11) C] carfentanil, we find that, following alcohol consumption, individuals with the COMT Val158 allele have greater opioid release in the right NAc but less release in medial orbital frontal cortex (OFC). These data suggest that genetic regulation of dopamine levels can affect alcohol consumption in part by modulating endogenous opioid release in specific brain regions implicated in reward, which in turn promotes impulsive choice. PMID:24127930

Mitchell, Jennifer M; O'Neil, James P; Jagust, William J; Fields, Howard L

2013-06-13

415

Preparation and comparative characterization of immobilized Aspergillus oryzae expressing Fusarium heterosporum lipase for enzymatic biodiesel production  

Microsoft Academic Search

In this paper, we provide the first report of utilizing recombinant fungal whole cells in enzymatic biodiesel production.\\u000a Aspergillus oryzae, transformed with a heterologous lipase-encoding gene from Fusarium heterosporum, produced fully processed and active forms of recombinant F. heterosporum lipase (FHL). Cell immobilization within porous biomass support particles enabled the convenient usage of FHL-producing A. oryzae as a whole-cell biocatalyst

Shinji Hama; Sriappareddy Tamalampudi; Yuya Suzuki; Ayumi Yoshida; Hideki Fukuda; Akihiko Kondo

2008-01-01

416

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

417

Efficacy of diflubenzuron plus methoprene against Sitophilus oryzae and Rhyzopertha dominica in stored sorghum  

Microsoft Academic Search

The efficacy of diflubenzuron (1mgkg?1)+methoprene (1mgkg?1) against Sitophilus oryzae (L.) and Rhyzopertha dominica (F.) in sorghum was evaluated in a silo-scale trial in southeast Queensland, Australia. Sorghum is normally protected from a wide range of insects by mixtures of grain protectants. The chitin synthesis inhibitor diflubenzuron was evaluated as a potential new protectant for S. oryzae in combination with the

Gregory J. Daglish; Barry E. Wallbank

2005-01-01

418

Functional analysis of the cyclopiazonic acid biosynthesis gene cluster in Aspergillus oryzae RIB 40.  

PubMed

The cyclopiazonic acid (CPA) nonproducing strain, Aspergillus oryzae RIB 40, does not biosynthesize cyclo-acetoacetyl-L-tryptophan (cAATrp) due to a truncation in the responsible PKS-NRPS gene. We found that RIB 40 converted cAATrp to 2-oxocyclopiazonic acid, the final product of CPA biosynthesis in A. oryzae. This indicates that the CPA biosynthesis gene cluster, except for the PKS-NRPS gene, is functional in RIB 40. PMID:22056451

Shinohara, Yasutomo; Tokuoka, Masafumi; Koyama, Yasuji

2011-11-07

419

A novel Aspergillus oryzae esterase that hydrolyzes 4-hydroxybenzoic acid esters.  

PubMed

In this study we report the biochemical characterization of a hypothetical protein from Aspergillus oryzae exhibiting sequence identity with feruloyl esterase and tannase from the genus Aspergillus. The purified recombinant protein showed a hydrolytic activity toward the ethyl, propyl, or butyl esters of 4-hydroxybenzoic acid, but did not show feruloyl esterase or tannase activity. Finally, the enzyme decreased the antimicrobial activity of parabens against A. oryzae via hydrolysis of the ester bond present in butyl 4-hydroxybenzoic acid. PMID:20728445

Koseki, Takuya; Mihara, Koji; Murayama, Tetsuya; Shiono, Yoshihito

2010-08-20

420

Fluorescent pseudomonad mixtures mediate disease resistance in rice plants against sheath rot ( Sarocladium oryzae ) disease  

Microsoft Academic Search

Plant growth-promoting rhizobacterial (PGPR) strains were isolated from different agro-ecosystems of Tamil Nadu, India, and\\u000a were tested for their efficacy against the sheath rot pathogen Sarocladium oryzae under in vitro, glasshouse and field conditions. Vigour and a relative performance index (RPI) were used to assay the growth\\u000a promotion and antagonistic activity of Pseudomonas strains against S. oryzae under in vitro conditions. The

Duraisamy Saravanakumar; Nallathambi Lavanya; Kannappan Muthumeena; Thiruvengadam Raguchander; Ramasamy Samiyappan

2009-01-01

421

Screening of allyl alcohol resistant mutant of Rhizopus oryzae and its fermentation characterization  

Microsoft Academic Search

Ethanol is a main by-product in the fermentation broth of Rhizopus oryzae during the production of high-optical purity L-lactic acid. By screening the lower activity of alcohol dehydrogenase (ADH) mutant, thus decreasing the flux of pyruvic acid to ethanol may be a virtual method for increasing the conversion rate of glucose to L-lactic acid. Mutagenesis of R. oryzae As3.3461 was

Zhi Zheng; Shui-Zhong Luo; Xing-Jiang Li; Xue-Feng Wu; Li-Jun Pan; Shao-Tong Jiang

422

A trial of minimization of chromosome 7 in Aspergillus oryzae by multiple chromosomal deletions  

Microsoft Academic Search

We aim to create an Aspergillus oryzae mutant with a highly reduced chromosome, but better growth, by eliminating the nonessential regions coding various dispensable\\u000a functions for its better industrial use. In our previous study, we successfully determined the outline of essential and nonessential\\u000a regions by constructing a series of large chromosomal deletions in A. oryzae chromosome 7. Based on these

Feng Jie Jin; Tadashi Takahashi; Michiyo Utsushikawa; Toshi Furukido; Michiyo Nishida; Masahiro Ogawa; Masahumi Tokuoka; Yasuji Koyama

2010-01-01

423

Current progress in the analysis of transcriptional regulation in the industrially valuable microorganism Aspergillus oryzae  

Microsoft Academic Search

Aspergillus oryzae is considered to be an attractive host for heterologous protein production because of its safety and ability to secrete large\\u000a amounts of proteins. In order to obtain high productivity, thus far promoters of amylases have been most widely used inA. oryzae. Recent progress in cloning and expression analysis, including EST sequencing, revealed that glycolytic genes represent some\\u000a of

Keiichi Nakajima; Motoaki Sano; Masayuki Machida

2000-01-01

424

?-Amylase production in high cell density submerged cultivation of Aspergillus oryzae and A. nidulans  

Microsoft Academic Search

The effect of biomass concentration on the formation of Aspergillus oryzae?-amylase during submerged cultivation with A. oryzae and recombinant A. nidulans strains has been investigated. It was found that the specific rate of ?-amylase formation in chemostats decreased significantly\\u000a with increasing biomass concentration in the range of approx. 2–12?g dry weight kg?1. When using a recombinant A. nidulans strain in

T. Agger; A. B. Spohr; J. Nielsen

2001-01-01

425

Low Enzymatic Activity Haplotypes of the Human Catechol-O-Methyltransferase Gene: Enrichment for Marker SNPs  

PubMed Central

Catechol-O-methyltransferase (COMT) is an enzyme that plays a key role in the modulation of catechol-dependent functions such as cognition, cardiovascular function, and pain processing. Three common haplotypes of the human COMT gene, divergent in two synonymous and one nonsynonymous (val158met) position, designated as low (LPS), average (APS), and high pain sensitive (HPS), are associated with experimental pain sensitivity and risk of developing chronic musculoskeletal pain conditions. APS and HPS haplotypes produce significant functional effects, coding for 3- and 20-fold reductions in COMT enzymatic activity, respectively. In the present study, we investigated whether additional minor single nucleotide polymorphisms (SNPs), accruing in 1 to 5% of the population, situated in the COMT transcript region contribute to haplotype-dependent enzymatic activity. Computer analysis of COMT ESTs showed that one synonymous minor SNP (rs769224) is linked to the APS haplotype and three minor SNPs (two synonymous: rs6267, rs740602 and one nonsynonymous: rs8192488) are linked to the HPS haplotype. Results from in silico and in vitro experiments revealed that inclusion of allelic variants of these minor SNPs in APS or HPS haplotypes did not modify COMT function at the level of mRNA folding, RNA transcription, protein translation, or enzymatic activity. These data suggest that neutral variants are carried with APS and HPS haplotypes, while the high activity LPS haplotype displays less linked variation. Thus, both minor synonymous and nonsynonymous SNPs in the coding region are markers of functional APS and HPS haplotypes rather than independent contributors to COMT activity.

Nackley, Andrea G.; Shabalina, Svetlana A.; Lambert, Jason E.; Conrad, Mathew S.; Gibson, Dustin G.; Spiridonov, Alexey N.; Satterfield, Sarah K.; Diatchenko, Luda

2009-01-01

426

Molecular origin of cancer: Catechol estrogen-3,4-quinones as endogenous tumor initiators  

PubMed Central

Cancer is a disease that begins with mutation of critical genes: oncogenes and tumor suppressor genes. Our research on carcinogenic aromatic hydrocarbons indicates that depurinating hydrocarbon–DNA adducts generate oncogenic mutations found in mouse skin papillomas (Proc. Natl. Acad. Sci. USA 92:10422, 1995). These mutations arise by mis-replication of unrepaired apurinic sites derived from the loss of depurinating adducts. This relationship led us to postulate that oxidation of the carcinogenic 4-hydroxy catechol estrogens (CE) of estrone (E1) and estradiol (E2) to catechol estrogen-3,4-quinones (CE-3, 4-Q) results in electrophilic intermediates that covalently bind to DNA to form depurinating adducts. The resultant apurinic sites in critical genes can generate mutations that may initiate various human cancers. The noncarcinogenic 2-hydroxy CE are oxidized to CE-2,3-Q and form only stable DNA adducts. As reported here, the CE-3,4-Q were bound to DNA in vitro to form the depurinating adduct 4-OHE1(E2)-1(?,?)-N7Gua at 59–213 ?mol/mol DNA–phosphate whereas the level of stable adducts was 0.1 ?mol/mol DNA–phosphate. In female Sprague–Dawley rats treated by intramammillary injection of E2-3,4-Q (200 nmol) at four mammary glands, the mammary tissue contained 2.3 ?mol 4-OHE2-1(?,?)-N7Gua/molDNA–phosphate. When 4-OHE1(E2) were activated by horseradish peroxidase, lactoperoxidase, or cytochrome P450, 87–440 ?mol of 4-OHE1(E2)-1(?, ?)-N7Gua was formed. After treatment with 4-OHE2, rat mammary tissue contained 1.4 ?mol of adduct/mol DNA–phosphate. In each case, the level of stable adducts was negligible. These results, complemented by other data, strongly support the hypothesis that CE-3,4-Q are endogenous tumor initiators.

Cavalieri, E. L.; Stack, D. E.; Devanesan, P. D.; Todorovic, R.; Dwivedy, I.; Higginbotham, S.; Johansson, S. L.; Patil, K. D.; Gross, M. L.; Gooden, J. K.; Ramanathan, R.; Cerny, R. L.; Rogan, E. G.

1997-01-01

427

Orientation and Cellular Distribution of Membrane-bound Catechol-O-methyltransferase in Cortical Neurons  

PubMed Central

Catechol-O-methyltransferase (COMT) is a key enzyme for inactivation and metabolism of catechols, including dopamine, norepinephrine, caffeine, and estrogens. It plays an important role in cognition, arousal, pain sensitivity, and stress reactivity in humans and in animal models. The human COMT gene is associated with a diverse spectrum of human behaviors and diseases from cognition and psychiatric disorders to chronic pain and cancer. There are two major forms of COMT proteins, membrane-bound (MB) COMT and soluble (S) COMT. MB-COMT is the main form in the brain. The cellular distribution of MB-COMT in cortical neurons remains unclear and the orientation of MB-COMT on the cellular membrane is controversial. In this study, we demonstrate that MB-COMT is located in the cell body and in axons and dendrites of rat cortical neurons. Analyses of MB-COMT orientation with computer simulation, flow cytometry and a cell surface enzyme assay reveal that the C-terminal catalytic domain of MB-COMT is in the extracellular space, which suggests that MB-COMT can inactivate synaptic and extrasynaptic dopamine on the surface of presynaptic and postsynaptic neurons. Finally, we show that the COMT inhibitor tolcapone induces cell death via the mechanism of apoptosis, and its cytotoxicity is dependent on dosage and correlated with COMT Val/Met genotypes in human lymphoblastoid cells. These results suggest that MB-COMT specific inhibitors can be developed and that tolcapone may be less hazardous at low doses and in specific genetic backgrounds.

Chen, Jingshan; Song, Jian; Yuan, Peixiong; Tian, Qingjun; Ji, Yuanyuan; Ren-Patterson, Renee; Liu, Guangping; Sei, Yoshitasu; Weinberger, Daniel R.

2011-01-01

428

In vitro evaluation of GR69153, a novel catechol-substituted cephalosporin.  

PubMed Central

GR69153 is a C-7 catechol cephalosporin with a broad spectrum of activity against members of the family Enterobacteriaceae (MICs for 50% of strains tested [MIC50s], 0.008 to 0.5 micrograms/ml), Staphylococcus aureus (MIC50, 4 micrograms/ml), Pseudomonas aeruginosa (MIC50, 0.25 micrograms/ml), Haemophilus influenzae (MIC50, 0.03 micrograms/ml), Neisseria gonorrhoeae (MIC50, 0.03 micrograms/ml), and Acinetobacter spp. (MIC50, 2 micrograms/ml). Potent GR69153 activity was also demonstrated against Moraxella catarrhalis, pneumococci, beta-hemolytic streptococci, gram-positive anaerobes, and most species of coagulase-negative staphylococci. The activity of GR69153 was generally two- to fourfold greater than that of ceftazidime. Resistance level GR69153 MICs for 90% of strains tested (greater than or equal to 32 micrograms/ml) were found most often among Citrobacter freundii, Enterobacter spp. and Morganella morganii strains. GR69153 did not significantly inhibit enterococci, Xanthomonas maltophilia, the Bacteroides fragilis group, Corynebacterium jeikeium, or Listeria monocytogenes. GR69153 was bactericidal and was generally beta-lactamase stable, and MICs were only slightly increased by high inoculum concentrations. Activity was enhanced in an iron-deficient medium, and a modest MIC difference attributed to iron availability was noted between standard agar and broth test results. GR69153 was confirmed to be a potent, catechol-substituted cephalosporin with a spectrum slightly wider than that of ceftazidime, but it was less active than cefpirome or imipenem against some gram-positive pathogens and anaerobes.

Erwin, M E; Jones, R N; Barrett, M S; Briggs, B M; Johnson, D M

1991-01-01

429

Mitochondrial NADH oxidase activity of Setaria cervi.  

PubMed

The bovine filarial parasite, Setaria cervi, has been found to contain NAD(P)H oxidase activity. The system was predominantly located in the mitochondrial membranes, with very little activity available in the soluble fraction of the organelle. The membrane preparation also exhibited the presence of a reduced pyridine nucleotide transhydrogenase which converted NADPH into NADH by transferring a hydride ion. The oxidase activity was inhibited by all the respiratory inhibitors examined, with the greatest sensitivity to rotenone, a site I-specific inhibitor. The system was also found to be susceptible to exposure to anthelmintics, amongst which levamisole proved the most effective. PMID:2267725

Goyal, N; Srivastava, V M

1990-11-01

430

In situ generation of hydrogen peroxide by carbohydrate oxidase and cellobiose dehydrogenase for bleaching purposes.  

PubMed

The carbohydrate oxidase from Microdochium nivale (CAOX), heterologously expressed in Aspergillus oryzae, and cellobiose dehydrogenase from Myriococcum thermophilum (MtCDH), were assessed for their ability to generate bleaching species at a pH suitable for liquid detergents. The substrate specificities of CAOX and MtCDH were analyzed on a large variety of soluble and insoluble substrates, using oxygen as an electron receptor. Even insoluble substrates like cellulose were oxidized from both CAOX and MtCDH, but only MtCDH produced H?O? on cotton as the sole substrate. To enhance the amount of cello-oligosaccharides formed from cotton as substrates for CAOX and MtCDH, various cellulases were used in combination with MtCDH or CAOX, leading to a 10-fold increase in H?O?. As model substrates for colored stains, the degradation of pure anthocyanins and stain removal of blueberry stains by CAOX and MtCDH was examined in the absence and presence of a horseradish peroxidase. Both enzymes were able to produce an amount of H?O? sufficient to decolorize the pure anthocyanins within 2 h and showed significant cleaning benefits on the stains. PMID:21298807

Pricelius, Sina; Ludwig, Roland; Lant, Neil J; Haltrich, Dietmar; Guebitz, Georg M

2010-11-29

431

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

432

Role of copper during carbon monoxide binding to terminal oxidases  

Microsoft Academic Search

Under fully reduced conditions, reassociation kinetics of CO were studied in several terminal oxidases containing copper in their binuclear center. The purified Paracoccus denitrificansba3-type quinol oxidase was found to recombine with CO monophasically (? 25–30 ms) like oxidases of the bo type from Escherichia coli, the caa3 type from Bacillus halodurans FTU, and the bo type from Methylobacillus flagellatum KT.

Maria S Muntyan; Bernd Ludwig; Irmela Zickermann; Nataliya P Starshinova

1998-01-01

433

Monoclonal antibodies to the alternative oxidase of higher plant mitochondria  

Microsoft Academic Search

The higher plant mitochondrial electron transport chain contains, in addition to the cytochrome chain which terminates with cytochrome oxidase, an alternative pathway that terminates with an alternative oxidase. The alternative oxidase of Sauromatum guttatum Schott has recently been identified as a cluster of proteins with apparent M{sub r} of 37, 36, and 35 kilodaltons (kD). Monoclonal antibodies have now been

T. E. Elthon; R. L. Nickels; L. McIntosh

1989-01-01

434

The high affinity iron permease is a key virulence factor required for Rhizopus oryzae pathogenesis  

PubMed Central

SUMMARY Rhizopus oryzaeis the most common cause of mucormycosis, an angioinvasive fungal infection that causes more then 50% mortality rate despite first-line therapy. Clinical and animal model data clearly demonstrate that the presence of elevated available serum iron predisposes the host to mucormycosis. The high affinity iron permease gene (FTR1) is required for R. oryzae iron transport in iron-depleted environments. Here we demonstrate that FTR1 is required for full virulence of R. oryzae in mice. We show that FTR1 is expressed during infection in diabetic ketoacidotic (DKA) mice. In addition, we disrupted FTR1 by double cross-over homologous recombination, but multinucleated R. oryzae could not be forced to segregate to a homokaryotic null allele. Nevertheless, a reduction of the relative copy number of FTR1 and inhibition of FTR1 expression by RNAi compromised the ability of R. oryzae to acquire iron in vitro and reduced its virulence in DKA mice. Importantly, passive immunization with anti-Ftr1p immune sera protected DKA mice from infection with R. oryzae. Thus FTR1 is a virulence factor for R. oryzae, and anti-Ftr1p passive immunotherapy deserves further evaluation as a strategy to improve outcomes of deadly mucormycosis.

Ibrahim, Ashraf S.; Gebremariam, Teclegiorgis; Lin, Lin; Luo, Guanpingsheng; Husseiny, Mohamed I.; Skory, Christopher D.; Fu, Yue; French, Samuel W.; Edwards, John E.; Spellberg, Brad

2010-01-01

435

Genomics of Aspergillus oryzae: Learning from the History of Koji Mold and Exploration of Its Future  

PubMed Central

At a time when the notion of microorganisms did not exist, our ancestors empirically established methods for the production of various fermentation foods: miso (bean curd seasoning) and shoyu (soy sauce), both of which have been widely used and are essential for Japanese cooking, and sake, a magical alcoholic drink consumed at a variety of ritual occasions, are typical examples. A filamentous fungus, Aspergillus oryzae, is the key organism in the production of all these traditional foods, and its solid-state cultivation (SSC) has been confirmed to be the secret for the high productivity of secretory hydrolases vital for the fermentation process. Indeed, our genome comparison and transcriptome analysis uncovered mechanisms for effective degradation of raw materials in SSC: the extracellular hydrolase genes that have been found only in the A. oryzae genome but not in A. fumigatus are highly induced during SSC but not in liquid cultivation. Also, the temperature reduction process empirically adopted in the traditional soy-sauce fermentation processes has been found to be important to keep strong expression of the A. oryzae-specific extracellular hydrolases. One of the prominent potentials of A. oryzae is that it has been successfully applied to effective degradation of biodegradable plastic. Both cutinase, responsible for the degradation of plastic, and hydrophobin, which recruits cutinase on the hydrophobic surface to enhance degradation, have been discovered in A. oryzae. Genomic analysis in concert with traditional knowledge and technology will continue to be powerful tools in the future exploration of A. oryzae.

Machida, Masayuki; Yamada, Osamu; Gomi, Katsuya

2008-01-01

436

Stability of ribonuclease T2 from Aspergillus oryzae.  

PubMed Central

The stability of ribonuclease T2 (RNase T2) from Aspergillus oryzae against guanidine hydrochloride and heat was studied by using CD and fluorescence. RNase T2 unfolded and refolded reversibly concomitant with activity, but the unfolding and refolding rates were very slow (order of hours). The free energy change for unfolding of RNase T2 in water was estimated to be 5.3 kcal.mol-1 at 25 degrees C by linear extrapolation method. From the thermal unfolding experiment in 20 mM sodium phosphate buffer at pH 7.5, the Tm and the enthalpy change of RNase T2 were found to be 55.3 degrees C and 119.1 kcal.mol-1, respectively. From these equilibrium and kinetic studies, it was found that the stability of RNAse T2 in the native state is predominantly due to the slow rate of unfolding.

Kawata, Y.; Hamaguchi, K.

1995-01-01

437

The crystal structure of acidic ?-galactosidase from Aspergillus oryzae.  

PubMed

The crystal structure of the industrially important Aspergillus oryzae ?-galactosidase has been determined at 2.60 Ĺ resolution. The Ao-?-gal is a large (985 residues) monomeric multi-domain enzyme that has a catalytic (?/?)8-barrel domain. An electron density map revealed extensive N-glycosylation between the domain interfaces suggesting that the oligosaccharide-chains would have a stabilizing role for the structure of Ao-?-gal. Comparison of structure with other ?-galactosidase structures of glycoside hydrolase family 35 revealed a number of hydrophobic residues, which may contribute favorably to the stabilization of the structure. The role of a high number of acidic residues in Ao-?-gal is also discussed. PMID:23688418

Maksimainen, Mirko M; Lampio, Anja; Mertanen, Mirka; Turunen, Ossi; Rouvinen, Juha

2013-05-17

438

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.

Semon, Mande; Nielsen, Rasmus; Jones, Monty P.; McCouch, Susan R.

2005-01-01

439

Identification and fine-mapping of Xa33, a novel gene for resistance to Xanthomonas oryzae pv. oryzae.  

PubMed

Broadening of the genetic base for identification and transfer of genes for resistance to insect pests and diseases from wild relatives of rice is an important strategy in resistance breeding programs across the world. An accession of Oryza nivara, International Rice Germplasm Collection (IRGC) accession number 105710, was identified to exhibit high level and broad-spectrum resistance to Xanthomonas oryzae pv. oryzae. In order to study the genetics of resistance and to tag and map the resistance gene or genes present in IRGC 105710, it was crossed with the bacterial blight (BB)-susceptible varieties 'TN1' and 'Samba Mahsuri' (SM) and then backcrossed to generate backcross mapping populations. Analysis of these populations and their progeny testing revealed that a single dominant gene controls resistance in IRGC 105710. The BC(1)F(2) population derived from the cross IRGC 105710/TN1//TN1 was screened with a set of 72 polymorphic simple-sequence repeat (SSR) markers distributed across the rice genome and the resistance gene was coarse mapped on chromosome 7 between the SSR markers RM5711 and RM6728 at a genetic distance of 17.0 and 19.3 centimorgans (cM), respectively. After analysis involving 49 SSR markers located between the genomic interval spanned by RM5711 and RM6728, and BC(2)F(2) population consisting of 2,011 individuals derived from the cross IRGC 105710/TN1//TN1, the gene was fine mapped between two SSR markers (RMWR7.1 and RMWR7.6) located at a genetic distance of 0.9 and 1.2 cM, respectively, from the gene and flanking it. The linkage distances were validated in a BC(1)F(2) mapping population derived from the cross IRGC 105710/SM//2 × SM. The BB resistance gene present in the O. nivara accession was identified to be novel based on its unique map location on chromosome 7 and wider spectrum of BB resistance; this gene has been named Xa33. The genomic region between the two closely flanking SSR markers was in silico analyzed for putatively expressed candidate genes. In total, eight genes were identified in the region and a putative gene encoding serinethreonine kinase appears to be a candidate for the Xa33 gene. PMID:21970567

Kumar, P Natraj; Sujatha, K; Laha, G S; Rao, K Srinivasa; Mishra, B; Viraktamath, B C; Hari, Y; Reddy, C S; Balachandran, S M; Ram, T; Madhav, M Sheshu; Rani, N Shobha; Neeraja, C N; Reddy, G Ashok; Shaik, H; Sundaram, R M

2012-02-01

440

Biochemical characterization of Magnaporthe oryzae ?-glucosidases for efficient ?-glucan hydrolysis.  

PubMed

?-Glucosidases designated MoCel3A and MoCel3B were successfully overexpressed in Magnaporthe oryzae. MoCel3A and MoCel3B showed optimal activity at 50 °C and pH 5.0-5.5. MoCel3A exhibited higher activity on higher degree of polymerization (DP) oligosaccharides and on ?-1,3-linked oligosaccharides than on ?-1,4-linked oligosaccharides. Furthermore, MoCel3A could liberate glucose from polysaccharides such as laminarin, 1,3-1,4-?-glucan, phosphoric acid-swollen cellulose, and pustulan, of which laminarin was the most suitable substrate. Conversely, MoCel3B preferentially hydrolyzed lower DP oligosaccharides such as cellobiose, cellotriose, and laminaribiose. Furthermore, the synergistic effects of combining enzymes including MoCel3A and MoCel3B were investigated. Depolymerization of 1,3-1,4-?-glucan by M. oryzae cellobiohydrolase (MoCel6A) enhanced the production of glucose by the actions of MoCel3A and MoCel3B. In these reactions, MoCel3A hydrolyzed higher DP oligosaccharides, resulting in the release of glucose and cellobiose, and MoCel3B preferentially hydrolyzed lower DP oligosaccharides including cellobiose. On the other hand, MoCel3A alone produced glucose from laminarin at levels equivalent to 80% of maximal hydrolysis obtained by the combined action of MoCel3A, MoCel3B, and endo-1,3-?-glucanase. Therefore, MoCel3A and MoCel3B activities yield glucose from not only cellulosic materials but also hemicellulosic polysaccharides. PMID:21626020

Takahashi, Machiko; Konishi, Teruko; Takeda, Takumi

2011-05-29

441

Some properties of two aldolases in extracts of Aspergillus oryzae.  

PubMed

Fructose 1,6-diphosphate (FDP) aldolase and 2-keto-3-deoxy-D-gluconate (KDG) aldolase the two key enzymes of Embden-Meyerhof-Parnas (EMP) and the nonphosphorolytic Entner-Doudoroff (ED) pathways respectively, were identified in cell-free extracts of four Aspergillus oryzae strains grown on D-glucose as sole source of carbon. A. oryzae NRRL 3435 gave the highest enzymatic activity for the two enzymes and selected for further studies. Studies on the properties of the two key enzymes indicated that the optimum conditi