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1

The crystal structure of an extracellular catechol oxidase from the ascomycete fungus Aspergillus oryzae.  

PubMed

Catechol oxidases (EC 1.10.3.1) catalyse the oxidation of o-diphenols to their corresponding o-quinones. These oxidases contain two copper ions (CuA and CuB) within the so-called coupled type 3 copper site as found in tyrosinases (EC 1.14.18.1) and haemocyanins. The crystal structures of a limited number of bacterial and fungal tyrosinases and plant catechol oxidases have been solved. In this study, we present the first crystal structure of a fungal catechol oxidase from Aspergillus oryzae (AoCO4) at 2.5-Ĺ resolution. AoCO4 belongs to the newly discovered family of short-tyrosinases, which are distinct from other tyrosinases and catechol oxidases because of their lack of the conserved C-terminal domain and differences in the histidine pattern for CuA. The sequence identity of AoCO4 with other structurally known enzymes is low (less than 30 %), and the crystal structure of AoCO4 diverges from that of enzymes belonging to the conventional tyrosinase family in several ways, particularly around the central ?-helical core region. A diatomic oxygen moiety was identified as a bridging molecule between the two copper ions CuA and CuB separated by a distance of 4.2-4.3 Ĺ. The UV/vis absorption spectrum of AoCO4 exhibits a distinct maximum of absorbance at 350 nm, which has been reported to be typical of the oxy form of type 3 copper enzymes. PMID:24043469

Hakulinen, Nina; Gasparetti, Chiara; Kaljunen, Heidi; Kruus, Kristiina; Rouvinen, Juha

2013-12-01

2

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

3

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

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

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

Microsoft Academic Search

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

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

1988-01-01

11

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

12

THE GENETIC CONTROL AND BIOCHEMICAL MODIFICATION OF CATECHOL OXIDASE IN MAIZE  

Microsoft Academic Search

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

TONY PRYOR

13

Enzymatic dynamics of catechol oxidase from Gastrolina depressa  

Microsoft Academic Search

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

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

2010-01-01

14

Biochemical and structural characterisation of the copper containing oxidoreductases catechol oxidase, tyrosinase, and laccase from ascomycete fungi.  

E-print Network

??Catechol oxidase (EC 1.10.3.1), tyrosinase (EC 1.14.18.1), and laccase (EC 1.10.3.2) are copper-containing metalloenzymes. They oxidise substituted phenols and use molecular oxygen as a terminal… (more)

Gasparetti, Chiara

2012-01-01

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

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

17

Crystal structure of a plant catechol oxidase containing a dicopper center  

Microsoft Academic Search

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

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

1998-01-01

18

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

19

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

20

Linkage between catecholate siderophores and the multicopper oxidase CueO in Escherichia coli.  

PubMed

The multicopper oxidase CueO had previously been demonstrated to exhibit phenoloxidase activity and was implicated in intrinsic copper resistance in Escherichia coli. Catecholates can potentially reduce Cu(II) to the prooxidant Cu(I). In this report we provide evidence that CueO protects E. coli cells by oxidizing enterobactin, the catechol iron siderophore of E. coli, in the presence of copper. In vitro, a mixture of enterobactin and copper was toxic for E. coli cells, but the addition of purified CueO led to their survival. Deletion of fur resulted in copper hypersensitivity that was alleviated by additional deletion of entC, preventing synthesis of enterobactin. In addition, copper added together with 2,3-dihydroxybenzoic acid or enterobactin was able to induce a Phi(cueO-lacZ) operon fusion more efficiently than copper alone. The reaction product of the 2,3-dihydroxybenzoic acid oxidation by CueO that can complex Cu(II) ions was determined by gas chromatography-mass spectroscopy and identified as 2-carboxymuconate. PMID:15317788

Grass, Gregor; Thakali, Keshari; Klebba, Phillip E; Thieme, Daniel; Müller, Axel; Wildner, Günter F; Rensing, Christopher

2004-09-01

21

Catechol oxidase activity of dicopper complexes with N-donor ligands  

Microsoft Academic Search

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

Katalin Selmeczi; Marius Réglier; Michel Giorgi; Gábor Speier

2003-01-01

22

Conversion of trypsin to a copper enzyme: tyrosinase/catechol oxidase by chemical modification.  

PubMed

New active sites can be introduced into naturally occurring enzymes by the chemical modification of specific amino acid residues in concert with genetic techniques. Chemical strategies have had a significant impact in the field of enzyme design such as modifying the selectivity and catalytic activity which is very different from those of the corresponding native enzymes. Thus, chemical modification has been exploited for the incorporation of active site binding analogs onto protein templates and for atom replacement in order to generate new functionality such as the conversion of a hydrolase into a peroxidase. The introduction of a coordination complex into a substrate binding pocket of trypsin could probably also be extended to various enzymes of significant therapeutic and biotechnological importance. The aim of this study is the conversion of trypsin into a copper enzyme: tyrosinase by chemical modification. Tyrosinase is a biocatalyst (EC.1.14.18.1) containing two atoms of copper per active site with monooxygenase activity. The active site of trypsin (EC 3.4.21.4), a serine protease was chemically modified by copper (Cu(+2)) introduced p-aminobenzamidine (pABA- Cu(+2): guanidine containing schiff base metal chelate) which exhibits affinity for the carboxylate group in the active site as trypsin-like inhibitor. Trypsin and the resultant semisynthetic enzyme preparation was analysed by means of its trypsin and catechol oxidase/tyrosinase activity. After chemical modification, trypsin-pABA-Cu(+2) preparation lost 63% of its trypsin activity and gained tyrosinase/catechol oxidase activity. The kinetic properties (K(cat), K(m), K(cat)/K(m)), optimum pH and temperature of the trypsin-pABA-Cu(+2) complex was also investigated. PMID:20024799

Okutucu, Burcu; Zeytunluoglu, Ali; Zihnioglu, Figen

2010-01-01

23

The reactivity of ortho-methoxy-substituted catechol radicals with sulfhydryl groups: Contribution for the comprehension of the mechanism of inhibition of NADPH oxidase by apocynin  

Microsoft Academic Search

Redox processes are involved in the mechanism of action of NADPH oxidase inhibitors such as diphenyleneiodonium and apocynin. Here, we studied the structure-activity relationship for apocynin and analogous ortho-methoxy-substituted catechols as inhibitors of the NADPH oxidase in neutrophils and their reactivity with peroxidase. Aiming to alter the reduction potential, the ortho-methoxy-catechol moiety was kept constant and the substituents at para

Marília P. P. Kanegae; Luiz Marcos da Fonseca; Iguatemy L. Brunetti; Sueli de Oliveira Silva; Valdecir F. Ximenes

2007-01-01

24

Simultaneous inhibition of catechol-O-methyltransferase and monoamine oxidase A: Effects on hemodynamics and catecholamine metabolism in healthy volunteers  

Microsoft Academic Search

Objective: To evaluate the effects of simultaneous pharmacologic inhibition of catechol-O-methyltransferase (COMT) and monoamine oxidase type A (MAO-A) on hemodynamics and catecholamine metabolism in healthy volunteers at rest and during exercise.Background: Entacapone, a COMT inhibitor, is studied as an adjunct to levodopa treatment in patients with Parkinson's disease. Moclobemide, an MAO-A inhibitor, is already in clinical use as an antidepressant.

Ari Illi; Stig Sundberg; Pirjo Ojala-Karlsson; Mika Scheinin; Ariel Gordin

1996-01-01

25

Substrate specificity of catechol oxidase from Lycopus europaeus and characterization of the bioproducts of enzymic caffeic acid oxidation 1 Dedicated to Prof. Dr. Dr. H. Witzel on the occasion of his 75th birthday, deceased 1 September 1996. 1  

Microsoft Academic Search

The substrate specificity of catechol oxidase from Lycopus europaeus towards phenols is examined. The enzyme catalyzes the oxidation of o-diphenols to o-quinones without hydroxylating monophenols, the additional activity of tyrosinase. Substrates containing a -COOH group are inhibitors for catechol oxidase. The products of enzymic oxidation of caffeic acid were analyzed and isolated by HPLC with diode array detection. The neolignans

Annette Rompel; Helmut Fischer; Dirk Meiwes; Klaudia Büldt-Karentzopoulos; Annette Magrini; Christoph Eicken; Carsten Gerdemann; Bernt Krebs

1999-01-01

26

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

27

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

Microsoft Academic Search

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

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

1996-01-01

28

The reactivity of ortho-methoxy-substituted catechol radicals with sulfhydryl groups: contribution for the comprehension of the mechanism of inhibition of NADPH oxidase by apocynin.  

PubMed

Redox processes are involved in the mechanism of action of NADPH oxidase inhibitors such as diphenyleneiodonium and apocynin. Here, we studied the structure-activity relationship for apocynin and analogous ortho-methoxy-substituted catechols as inhibitors of the NADPH oxidase in neutrophils and their reactivity with peroxidase. Aiming to alter the reduction potential, the ortho-methoxy-catechol moiety was kept constant and the substituents at para position related to the hydroxyl group were varied. Two series of compounds were employed: methoxy-catechols bearing electron-withdrawing groups (MC-W) such as apocynin, vanillin, 4-nitroguaiacol, 4-cyanoguaiacol, and methoxy-catechol bearing electron-donating groups (MC-D) such as 4-methylguaiacol and 4-ethylguaiacol. We found that MC-D were weaker inhibitors compared to MD-W. Furthermore, the radicals generated by oxidation of MC-W via MPO/H(2)O(2), but not for MC-D, were able to oxidize glutathione (GSH) as verified by the formation of thiyl radicals, depletion of GSH, and recycling of the ortho-methoxy-catechols during their oxidations. The capacity of oxidizing sulfhydryl (SH) groups was also verified when ovalbumin was incubated with MC-W, but not for MC-D. Since the effect of apocynin has been correlated with inactivation of the cytosolic fractions of the NADPH oxidase complex and its oxidation during the inhibitory process develops a special role in this process, we suggest that the close relationship between the reactivity of the radicals of MC-W compounds with thiol groups and their efficacy as NADPH oxidase inhibitor could be the chemical pathway behind the mechanism of action of apocynin and should be taken into account in the design of new and specific NADPH oxidase inhibitors. PMID:17544376

Kanegae, Marília P P; da Fonseca, Luiz Marcos; Brunetti, Iguatemy L; Silva, Sueli de Oliveira; Ximenes, Valdecir F

2007-08-01

29

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

30

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

31

The contribution by monoamine oxidase and catechol-O-methyltransferase to the total-body and pulmonary plasma clearance of catecholamines  

Microsoft Academic Search

To study the effects of inhibition of catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO) on the removal of circulating catecholamines, anaesthetized rabbits were infused for 120 min with 3H-labelled noradrenaline, adrenaline and dopamine. Total-body plasma clearances (Cltot) and pulmonary fractional extractions (ERP) of the infused amines and the cardiac output of plasma (COP) were determined under steady-state conditions at the end

Bernd Friedgen; Reinhard Wölfel; Karl-Heinz Graefe

1996-01-01

32

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

33

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

34

Bilirubin oxidase from Magnaporthe oryzae: an attractive new enzyme for biotechnological applications  

PubMed Central

A novel bilirubin oxidase (BOD), from the rice blast fungus Magnaporthe oryzae, has been identified and isolated. The 64-kDa protein containing four coppers was successfully overexpressed in Pichia pastoris and purified to homogeneity in one step. Protein yield is more than 100 mg for 2 L culture, twice that of Myrothecium verrucaria. The kcat/Km ratio for conjugated bilirubin (1,513 mM ?1 s?1) is higher than that obtained for the BOD from M. verrucaria expressed in native fungus (980 mM?1 s?1), with the lowest Km measured for any BOD highly desirable for detection of bilirubin in medical samples. In addition, this protein exhibits a half-life for deactivation >300 min at 37 °C, high stability at pH 7, and high tolerance towards urea, making it an ideal candidate for the elaboration of biofuel cells, powering implantable medical devices. Finally, this new BOD is efficient in decolorizing textile dyes such as Remazol brilliant Blue R, making it useful for environmentally friendly industrial applications. PMID:22350257

Durand, Fabien; Gounel, Sebastien; Kjaergaard, Christian H.; Solomon, Edward I.

2013-01-01

35

Effects of monoamine oxidase and catechol- O-methyltransferase inhibition on dopamine turnover: A PET study with 6-[ 18 F ] l-DOPA  

Microsoft Academic Search

The consequences of monoamine oxidase and catechol-O-methyltransferase inhibition on the effective turnover of dopamine were investigated using 6-[18F]l-3-4-dihydroxyphenylalanine (6-[18F]l-DOPA) and positron emission tomography. The effective dopamine turnover was expressed as the ratio between the rate of reversibility of 6-[18F]l-DOPA trapping (kloss) and the rate of uptake of 6-[18F]l-DOPA (Ki) in the striatum of normal cynomolgus monkeys. The monkeys received 6-[18F]l-DOPA

Doris J Doudet; Grace L. Y Chan; James E Holden; Brian D Pate; K. Scott Morrison; Donald B Calne; Thomas J Ruth

1997-01-01

36

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

37

Microdialysis with radiometric monitoring of L-[?-11C]DOPA to assess dopaminergic metabolism: effect of inhibitors of L-amino acid decarboxylase, monoamine oxidase, and catechol-O-methyltransferase on rat striatal dialysate  

Microsoft Academic Search

The catecholamine, dopamine (DA), is synthesized from 3,4-dihydroxy-L-phenylalanine (L-DOPA) by aromatic L-amino acid decarboxylase (AADC). Dopamine metabolism is regulated by monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT). To measure dopaminergic metabolism, we used microdialysis with radiometric detection to monitor L-[?-11C]DOPA metabolites in the extracellular space of the rat striatum. We also evaluated the effects of AADC, MAO, and COMT inhibitors on

Maki Okada; Ryuji Nakao; Rie Hosoi; Ming-Rong Zhang; Toshimitsu Fukumura; Kazutoshi Suzuki; Osamu Inoue

2011-01-01

38

Polyamine oxidase 7 is a terminal catabolism-type enzyme in Oryza sativa and is specifically expressed in anthers.  

PubMed

Polyamine oxidase (PAO), which requires FAD as a cofactor, functions in polyamine catabolism. Plant PAOs are classified into two groups based on their reaction modes. The terminal catabolism (TC) reaction always produces 1,3-diaminopropane (DAP), H2O2, and the respective aldehydes, while the back-conversion (BC) reaction produces spermidine (Spd) from tetraamines, spermine (Spm) and thermospermine (T-Spm) and/or putrescine from Spd, along with 3-aminopropanal and H2O2. The Oryza sativa genome contains seven PAO-encoded genes termed OsPAO1-OsPAO7. To date, we have characterized four OsPAO genes. The products of these genes, i.e. OsPAO1, OsPAO3, OsPAO4 and OsPAO5, catalyze BC-type reactions. Whereas OsPAO1 remains in the cytoplasm, the other three PAOs localize to peroxisomes. Here, we examined OsPAO7 and its gene product. OsPAO7 shows high identity to maize ZmPAO1, the best characterized plant PAO having TC-type activity. OsPAO7 seems to remain in a peripheral layer of the plant cell with the aid of its predicted signal peptide and transmembrane domain. Recombinant OsPAO7 prefers Spm and Spd as substrates, and it produces DAP from both substrates in a time-dependent manner, indicating that OsPAO7 is the first TC-type enzyme identified in O. sativa. The results clearly show that two types of PAOs co-exist in O. sativa. Furthermore, OsPAO7 is specifically expressed in anthers, with an expressional peak at the bicellular pollen stage. The physiological function of OsPAO7 in anthers is discussed. PMID:24634478

Liu, Taibo; Kim, Dong Wook; Niitsu, Masaru; Maeda, Shunsuke; Watanabe, Masao; Kamio, Yoshiyuki; Berberich, Thomas; Kusano, Tomonobu

2014-06-01

39

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

PubMed Central

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

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

2010-01-01

40

Microdialysis with radiometric monitoring of -[?-11C]DOPA to assess dopaminergic metabolism: effect of inhibitors of -amino acid decarboxylase, monoamine oxidase, and catechol-O-methyltransferase on rat striatal dialysate  

PubMed Central

The catecholamine, dopamine (DA), is synthesized from 3,4-dihydroxy--phenylalanine (-DOPA) by aromatic -amino acid decarboxylase (AADC). Dopamine metabolism is regulated by monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT). To measure dopaminergic metabolism, we used microdialysis with radiometric detection to monitor -[?-11C]DOPA metabolites in the extracellular space of the rat striatum. We also evaluated the effects of AADC, MAO, and COMT inhibitors on metabolite profiles. The major early species measured after administration of -[?-11C]DOPA were [11C]3,4-dihydroxyphenylacetic acid ([11C]DOPAC) and [11C]homovanillic acid ([11C]HVA) in a 1:1 ratio, which shifted toward [11C]HVA with time. An AADC inhibitor increased the uptake of -[?-11C]DOPA and -3-O-methyl-[11C]DOPA and delayed the accumulation of [11C]DOPAC and [11C]HVA. The MAO and COMT inhibitors increased the production of [11C]3-methoxytyramine and [11C]DOPAC, respectively. These results reflect the -DOPA metabolic pathway, suggesting that this method may be useful for assessing dopaminergic metabolism. PMID:20407462

Okada, Maki; Nakao, Ryuji; Hosoi, Rie; Zhang, Ming-Rong; Fukumura, Toshimitsu; Suzuki, Kazutoshi; Inoue, Osamu

2011-01-01

41

Comparative Study of Substrates and Inhibitors ofAzospirillum lipoferumandPyricularia oryzaeLaccases  

Microsoft Academic Search

In animals, plants, fungi, and eubacteria, the main phenol oxidases (PO) are catechol oxidases (tyrosinases) and laccases. In the presence of molecular oxygen, laccases typically oxidize p- and o-diphenols, whereas catechol oxidases oxidize mono- phenols ando-diphenols (19), and the quinonic products may be polymerized into large molecules, such as melanins (4). Laccases have been detected in many fungi and higher

DENIS FAURE; MARIE-LOUISE BOUILLANT

1995-01-01

42

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

PubMed

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

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

2014-07-01

43

Behavioral/Systems/Cognitive Site-Specific Role of Catechol-O-Methyltransferase in  

E-print Network

Behavioral/Systems/Cognitive Site-Specific Role of Catechol-O-Methyltransferase in Dopamine and preclinical studies shows that catechol-O-methyltransferase (COMT) plays a significant role in dopamine transporter (Mundorf et al., 2001; Carboni and Silvagni, 2004) and monoamine oxidase (MAO) (Westerink

44

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

Microsoft Academic Search

Sulfhydryl oxidases have found application in the improvement of both dairy and baking products due to their ability to oxidise\\u000a thiol groups in small molecules and cysteine residues in proteins. A genome mining study of the available fungal genomes had\\u000a previously been performed by our group in order to identify novel sulfhydryl oxidases suitable for industrial applications\\u000a and a representative

Greta Faccio; Kristiina Kruus; Johanna Buchert; Markku Saloheimo

2011-01-01

45

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

46

Defensive Roles of Polyphenol Oxidase in Plants C. Peter Constabel and Raymond Barbehenn  

E-print Network

Oxidase Polyphenol oxidase (catechol oxidase; E.C. 1.10.3.2) has been purified and char- acterized fromChapter 12 Defensive Roles of Polyphenol Oxidase in Plants C. Peter Constabel and Raymond Barbehenn Plant polyphenol oxidases (PPOs) are widely distributed and well-studied oxidative enzymes

Constabel, Peter

47

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

48

Original article Variation for polyphenol oxidase activity  

E-print Network

Original article Variation for polyphenol oxidase activity in stems of Medicago species Michele) Abstract - Polyphenol oxidase (PPO) activity was detected in stems of both glandular-haired and glabrous from 120 to 180 kDa and the lighter one from 65 to 75 kDa. The substrate affinity for 4-methyl catechol

Paris-Sud XI, Université de

49

Activation of gibberellin 2-oxidase 6 decreases active gibberellin levels and creates a dominant semi-dwarf phenotype in rice (Oryza sativa L.).  

PubMed

Gibberellin (GA) 2-oxidase plays a key role in the GA catabolic pathway through 2beta-hydroxylation. In the present study, we isolated a CaMV 35S-enhancer activation tagged mutant, H032. This mutant exhibited a dominant dwarf and GA-deficient phenotype, with a final stature that was less than half of its wild-type counterpart. The endogenous bioactive GAs are markedly decreased in the H032 mutant, and application of bioactive GAs (GA(3) or GA(4)) can reverse the dwarf phenotype. The integrated T-DNA was detected 12.8 kb upstream of the OsGA2ox6 in the H032 genome by TAIL-PCR. An increased level of OsGA2ox6 mRNA was detected at a high level in the H032 mutant, which might be due to the enhancer role of the CaMV 35S promoter. RNAi and ectopic expression analysis of OsGA2ox6 indicated that the dwarf trait and the decreased levels of bioactive GAs in the H032 mutant were a result of the up-regulation of the OsGA2ox6 gene. BLASTP analysis revealed that OsGA2ox6 belongs to the class III of GA 2-oxidases, which is a novel type of GA2ox that uses C20-GAs (GA(12) and/or GA(53)) as the substrates. Interestingly, we found that a GA biosynthesis inhibitor, paclobutrazol, positively regulated the OsGA2ox6 gene. Unlike the over-expression of OsGA2ox1, which led to a high rate of seed abortion, the H032 mutant retained normal flowering and seed production. These results indicate that OsGA2ox6 mainly affects plant stature, and the dominant dwarf trait of the H032 mutant can be used as an efficient dwarf resource in rice breeding. PMID:20171575

Huang, Jian; Tang, Ding; Shen, Yi; Qin, Baoxiang; Hong, Lilan; You, Aiqing; Li, Ming; Wang, Xin; Yu, Hengxiu; Gu, Minghong; Cheng, Zhukuan

2010-01-01

50

Abstract Catechol-O-methyl transferase (COMT) cat-alyzes the first step in one of the major pathways in the  

E-print Network

Abstract Catechol-O-methyl transferase (COMT) cat- alyzes the first step in one of the major in disease etiology. Introduction Catechol-O-methyltransferase (COMT) is the enzyme cat- alyzing the first, epinephrine, and norepinephrine (Cooper et al. 1996). Do- pamine is mainly degraded by monoamine oxidase (MAO

Kidd, Kenneth

51

Inhibition of catechol-O-methyltransferase activity by two novel disubstituted catechols in the rat.  

PubMed

Catechol-O-methyltransferase (COMT) has an important role in the extraneuronal inactivation of catecholamine neurotransmitters and drugs with a catechol structure. Two novel COMT inhibitors, OR-462 and OR-486, were highly effective (IC50 = 18 and 12 nM, respectively) and selective in inhibiting COMT activity in vitro. Tyrosine hydroxylase was not inhibited until micromolar concentrations of these compounds were used: the IC50 values for OR-462 and OR-486 were 10 and 14 microM, respectively. The IC50 values for dopamine-beta-hydroxylase, dopa-decarboxylase and monoamine oxidase forms A and B were greater than 50 microM. In studies ex vivo oral OR-462 inhibited mainly the COMT activity in the duodenum while OR-486 inhibited COMT activity in the liver and red blood cells as well. Oral OR-462 did not penetrate into the brain in doses up to 30 mg/kg while the same dose of OR-486 had some effect on striatal COMT activity. When tested in combination with levodopa-carbidopa, orally administered OR-462 and OR-486 were more effective in reducing the formation of 3-O-methyldopa from levodopa than was the levodopa-carbidopa treatment alone. These results indicate that OR-462 and OR-486 are effective and long-lasting inhibitors of COMT activity. PMID:3181288

Nissinen, E; Lindén, I B; Schultz, E; Kaakkola, S; Männistö, P T; Pohto, P

1988-08-24

52

Determination of kinetic properties of polyphenol oxidase from Thymus ( Thymus longicaulis subsp. chaubardii var. chaubardii)  

Microsoft Academic Search

A partial characterization of polyphenol oxidase (PPO) activity of Thymus longicaulis subsp. chaubardii var. chaubardii is described. Polyphenol oxidase of Thymus was isolated by (NH4)2SO4 precipitation and dialysis. The effects of substrate specificity, pH, temperature, heat-inactivation and glutathione inhibitor on polyphenol oxidase activity obtained from T. longicaulis subsp. chaubardii var. chaubardii were investigated. Polyphenol oxidase showed activity toward catechol, 4-methylcatechol

Serap Dogan; Mehmet Dogan

2004-01-01

53

Analysis of cellulase and polyphenol oxidase production by southern pine beetle associated fungi  

E-print Network

In this study, the production of extracellular enzymes by fungi associated with southern pine beetle was investigated for the first time. Cellulase and polyphenol oxidase production were analyzed for three beetle associated fungi. Only the mutualistic symbiont Entomocorticium sp. A was found to produce cellulases and polyphenol oxidase. In time course analyses of cellulase production in batch cultures, Entomocorticium sp. A showed maximum activity of 0.109 U/ml and 0.141 U/ml for total cellulase and endoglucanase activity respectively. Polyphenol oxidase production was simultaneous with fungal growth. Characterization of polyphenol oxidase by activity staining suggests that the enzyme is a tyrosinase/catechol oxidase. Enzyme assays in the presence of polyphenol oxidase inhibitors support the results of the activity staining. Keywords: Ceratocystiopsis, Entomocorticium, Ophiostoma, cellulase, tyrosinase/catechol oxidase

Abduvali Valiev; Zumrut B. Ogel; Kier D. Klepzig

2008-01-01

54

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

55

Inhibition kinetics of polyphenol oxidase by glutamic acid  

Microsoft Academic Search

The inhibition of polyphenol oxidase (PPO) by glutamic acid was investigated. Application of different concentrations of glutamic\\u000a acid to mushroom solution and Ocimum basilicum L. extract showed that glutamic acid appeared to be an effective browning inhibitor. Glutamic acid showed uncompetitive inhibition\\u000a for mushroom and Ocimum basilicum L. polyphenol oxidases using 4-methylcatechol as a substrate, for mushroom PPO using catechol

Serap Do?an; P?nar Turan; Mehmet Do?an; Mahir Alkan; Oktay Arslan

2007-01-01

56

A semiempirical study on inhibition of catechol O-methyltransferase by substituted catechols.  

PubMed

Catechol and endogenous catechol derivatives are readily methylated by catechol O-methyltransferase (COMT). In contrast, many catechol derivatives possessing electronegative substituents are potent COMT inhibitors. The X-ray structure of the active site of COMT suggests that the methylation involves a lysine as a general base. The lysine can activate one of the catecholic hydroxyl groups for a nucleophilic attack on the active methyl group of the coenzyme S-adenosyl-L-methionine (AdoMet). We studied the effect of dinitrosubstitution of the catecholic ring at the semiempirical PM3 level on the methylation reaction catalysed by COMT. The electronegative nitro groups make the ionized catechol hydroxyls less nucleophilic than the corresponding hydroxyl groups of the non-substituted catechol. As a consequence, dinitrocatechol is not methylated but is instead a potent COMT inhibitor. The implications of this mechanism to the design of COMT inhibitors are discussed. PMID:9749372

Ovaska, M; Yliniemelä, A

1998-05-01

57

Human liver catechol-O-methyltransferase pharmacogenetics  

Microsoft Academic Search

Catechol-O-methyltransferase activity and thermal stability in the human red blood cell are controlled by a common genetic polymorphism. Approximately 25% to 30% of a randomly selected population sample is homozygous for the traits of low catechol-O-methyltransferase activity and thermolabile enzyme in the red blood cell. We tested the hypothesis that the catechol-O-methyltransferase genetic polymorphism might also control those same characteristics

Blanka Boudíková; Carol Szumlanski; Bonnie Maidak; Richard Weinshilboum

1990-01-01

58

Synthesis and hiv-1 integrase inhibitory activities of catechol and bis-Catechol derivatives  

Microsoft Academic Search

Fourteen catechol and bis-catechol derivatives have been synthesised and tested for their HIV-1 inhibitory activities. The six more active molecules have been tested for their antiviral activity and cytotoxicity. We have found that bis-catechols 1 and 2 are the most active HIV-1 integrase inhibitor whereas the best antiviral compound is 4.

Romain Dupont; Laurence Jeanson; Jean-François Mouscadet; Philippe Cotelle

2001-01-01

59

Synthesis and HIV-1 integrase inhibitory activities of catechol and bis-catechol derivatives.  

PubMed

Fourteen catechol and bis-catechol derivatives have been synthesised and tested for their HIV-1 inhibitory activities. The six more active molecules have been tested for their antiviral activity and cytotoxicity. We have found that bis-catechols 1 and 2 are the most active HIV-1 integrase inhibitor whereas the best antiviral compound is 4. PMID:11720868

Dupont, R; Jeanson, L; Mouscadet, J F; Cotelle, P

2001-12-17

60

Princeton University DFT Study of Catechol  

E-print Network

.kyocera.com/prdct/solar/spirit/about_solar/images/cell_05.gif #12;Princeton University Photoelectrochemical Cells Basic Regenerative Cell Dye sensitizing dyes #12;Princeton University Catecholate vs. Carboxylate · Lowers adsorption spectrum of TiO2Princeton University DFT Study of Catechol Adsorption on TiO2 Matthew Connors Professor Annabella

Petta, Jason

61

Comparison of Polyphenol Oxidases Prepared From Different Parts of Artichoke (Cynara Scolymus L.)  

Microsoft Academic Search

Artichoke polyphenol oxidases (PPOs) were obtained by (NH4)2SO4 precipitation using ascorbic acid, polyvinylpyrrolidone, and Triton X-100. The PPO content of artichoke head (AHPPO) was 8820 units (mg protein) as compared with 3370 units (mg protein) in artichoke leaves-and-stem (ALSPPO) by using catechol as a substrate. The substrates of both AHPPO and ALSPPO are o-diphenols, such as catechol, pyrogallol, and L-DOPA.

Didem Tuncay; Hulya Yagar

2011-01-01

62

Laccases and other polyphenol oxidases in ecto- and ericoid mycorrhizal fungi  

Microsoft Academic Search

Polyphenol oxidases are known to be produced by a range of ectomycorrhizal (ECM) and ericoid mycorrhizal fungi. These enzymes include laccase (EC 1.10.3.2), catechol oxidase (EC 1.10.3.1) and tyrosinase (EC 1.14.18.1), between which there exists considerable overlap in substrate affinities. In this review we consider the nature and function of these enzymes, along with the difficulties associated with assigning precise

R. M. Burke; J. W. G. Cairney

2002-01-01

63

PEM Anchorage on Titanium Using Catechol Grafting  

PubMed Central

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

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

2012-01-01

64

Crystal structure of catechol O-methyltransferase.  

PubMed

Catechol O-methyltransferase (COMT, EC 2.1.1.6) is important in the central nervous system because it metabolizes catecholamine neurotransmitters such as dopamine. The enzyme catalyses the transfer of the methyl group from S-adenosyl-L-methionine (AdoMet) to one hydroxyl group of catechols. COMT also inactivates catechol-type compounds such as L-DOPA. With selective inhibitors of COMT in combination with L-DOPA, a new principle has been realized in the therapy of Parkinson's disease. Here we solve the atomic structure of COMT to 2.0 A resolution, which provides new insights into the mechanism of the methyl transfer reaction. The co-enzyme-binding domain is strikingly similar to that of an AdoMet-dependent DNA methylase, indicating that all AdoMet methylases may have a common structure. PMID:8127373

Vidgren, J; Svensson, L A; Liljas, A

1994-03-24

65

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. PMID:23071628

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

66

Apocynin inhibits NADPH oxidase in phagocytes but stimulates ROS production in non-phagocytic cells  

Microsoft Academic Search

Apocynin is a naturally occurring methoxy-substituted catechol, experimentally used as an inhibitor of NADPH oxidase. Since it acts as a potent inhibitor in studies with neutrophils and macrophages, no inhibitory effect can often be found in non-phagocyte cells. In our experiments, apocynin even stimulated reactive oxygen species (ROS) production by vascular fibroblasts. Even when added to macrophages, apocynin initially caused

Martin Vejražka; Radan Mí?ek; Stanislav Štípek

2005-01-01

67

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

68

Catechol-based biomimetic functional materials.  

PubMed

Catechols are found in nature taking part in a remarkably broad scope of biochemical processes and functions. Though not exclusively, such versatility may be traced back to several properties uniquely found together in the o-dihydroxyaryl chemical function; namely, its ability to establish reversible equilibria at moderate redox potentials and pHs and to irreversibly cross-link through complex oxidation mechanisms; its excellent chelating properties, greatly exemplified by, but by no means exclusive, to the binding of Fe(3+); and the diverse modes of interaction of the vicinal hydroxyl groups with all kinds of surfaces of remarkably different chemical and physical nature. Thanks to this diversity, catechols can be found either as simple molecular systems, forming part of supramolacular structures, coordinated to different metal ions or as macromolecules mostly arising from polymerization mechanisms through covalent bonds. Such versatility has allowed catechols to participate in several natural processes and functions that range from the adhesive properties of marine organisms to the storage of some transition metal ions. As a result of such an astonishing range of functionalities, catechol-based systems have in recent years been subject to intense research, aimed at mimicking these natural systems in order to develop new functional materials and coatings. A comprehensive review of these studies is discussed in this paper. PMID:23180685

Sedó, Josep; Saiz-Poseu, Javier; Busqué, Felix; Ruiz-Molina, Daniel

2013-02-01

69

Herbicidal potential of catechol as an allelochemical.  

PubMed

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

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

2006-01-01

70

Jack of all trades: versatile catechol crosslinking mechanisms.  

PubMed

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

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

2014-12-21

71

Genome sequencing and analysis of Aspergillus oryzae  

Microsoft Academic Search

The genome of Aspergillus oryzae, a fungus important for the production of traditional fermented foods and beverages in Japan, has been sequenced. The ability to secrete large amounts of proteins and the development of a transformation system have facilitated the use of A. oryzae in modern biotechnology. Although both A. oryzae and Aspergillus flavus belong to the section Flavi of

Masayuki Machida; Kiyoshi Asai; Motoaki Sano; Toshihiro Tanaka; Toshitaka Kumagai; Goro Terai; Ken-Ichi Kusumoto; Toshihide Arima; Osamu Akita; Yutaka Kashiwagi; Keietsu Abe; Katsuya Gomi; Hiroyuki Horiuchi; Katsuhiko Kitamoto; Tetsuo Kobayashi; Michio Takeuchi; David W. Denning; James E. Galagan; William C. Nierman; Jiujiang Yu; David B. Archer; Joan W. Bennett; Deepak Bhatnagar; Thomas E. Cleveland; Natalie D. Fedorova; Osamu Gotoh; Hiroshi Horikawa; Akira Hosoyama; Masayuki Ichinomiya; Rie Igarashi; Kazuhiro Iwashita; Praveen Rao Juvvadi; Masashi Kato; Yumiko Kato; Taishin Kin; Akira Kokubun; Hiroshi Maeda; Noriko Maeyama; Jun-Ichi Maruyama; Hideki Nagasaki; Tasuku Nakajima; Ken Oda; Kinya Okada; Ian Paulsen; Kazutoshi Sakamoto; Toshihiko Sawano; Mikio Takahashi; Kumiko Takase; Yasunobu Terabayashi; Jennifer R. Wortman; Osamu Yamada; Youhei Yamagata; Hideharu Anazawa; Yoji Hata; Yoshinao Koide; Takashi Komori; Yasuji Koyama; Toshitaka Minetoki; Sivasundaram Suharnan; Akimitsu Tanaka; Katsumi Isono; Satoru Kuhara; Naotake Ogasawara; Hisashi Kikuchi

2005-01-01

72

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

Microsoft Academic Search

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

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

2006-01-01

73

Genome sequence and rapid evolution of the rice pathogen Xanthomonas oryzae pv. oryzae PXO99A  

Microsoft Academic Search

BACKGROUND: Xanthomonas oryzae pv. oryzae causes bacterial blight of rice (Oryza sativa L.), a major disease that constrains production of this staple crop in many parts of the world. We report here on the complete genome sequence of strain PXO99A and its comparison to two previously sequenced strains, KACC10331 and MAFF311018, which are highly similar to one another. RESULTS: The

Steven L Salzberg; Daniel D Sommer; Michael C Schatz; Adam M Phillippy; Pablo D Rabinowicz; Seiji Tsuge; Ayako Furutani; Hirokazu Ochiai; Arthur L Delcher; David Kelley; Ramana Madupu; Daniela Puiu; Diana Radune; Martin Shumway; Cole Trapnell; Gudlur Aparna; Gopaljee Jha; Alok Pandey; Prabhu B Patil; Hiromichi Ishihara; Damien F Meyer; Boris Szurek; Valerie Verdier; Ralf Koebnik; J Maxwell Dow; Robert P Ryan; Hisae Hirata; Shinji Tsuyumu; Sang Won Lee; Pamela C Ronald; Ramesh V Sonti; Marie-Anne Van Sluys; Jan E Leach; Frank F White; Adam J Bogdanove

2008-01-01

74

Damage to Aspergillus fumigatus and Rhizopus oryzae Hyphae by Oxidative and Nonoxidative Microbicidal Products of Human Neutrophils In Vitro  

PubMed Central

Our previous studies established that human neutrophils could damage and probably kill hyphae of Aspergillus fumigatus and Rhizopus oryzae in vitro, primarily by oxygen-dependent mechanisms active at the cell surface. These studies were extended, again quantitating hyphal damage by reduction in uptake of 14C-labeled uracil or glutamine. Neither A. fumigatus nor R. oryzae hyphae were damaged by neutrophils from patients with chronic granulomatous disease, confirming the importance of oxidative mechanisms in damage to hyphae. In contrast, neutrophils from one patient with hereditary myeloperoxidase deficiency damaged R. oryzae but not A. fumigatus hyphae. Cell-free, in vitro systems were then used to help determine the relative importance of several potentially fungicidal products of neutrophils. Both A. fumigatus and R. oryzae hyphae were damaged by the myeloperoxidase-hydrogen peroxide-halide system either with reagent hydrogen peroxide or enzymatic systems for generating hydrogen peroxide (glucose oxidase with glucose, or xanthine oxidase with either hypoxanthine or acetaldehyde). Iodide with or without chloride supported the reaction, but damage was less with chloride alone as the halide cofactor. Hydrogen peroxide alone damaged hyphae only in concentrations ?1 mM, but 0.01 mM hypochlorous acid, a potential product of the myeloperoxidase system, significantly damaged R. oryzae hyphae (a 1 mM concentration was required for significant damage to A. fumigatus hyphae). Damage to hyphae by the myeloperoxidase system was inhibited by azide, cyanide, catalase, histidine, and tryptophan, but not by superoxide dismutase, dimethyl sulfoxide, or mannitol. Photoactivation of the dye rose bengal resulted in hyphal damage which was inhibited by histidine, tryptophan, and 1,4-diazobicyclo(2,2,2)octane. Lysates of neutrophils or separated neutrophil granules did not affect A. fumigatus hyphae, but did damage R. oryzae hyphae. Similarly, three preparations of cationic proteins purified from human neutrophil granules were more active in damaging R. oryzae than A. fumigatus hyphae. This damage, as with the separated granules and whole cell lysates, was inhibited by the polyanion heparin. Damage to R. oryzae hyphae by neutrophil cationic proteins was enhanced by activity of the complete myeloperoxidase system or by hydrogen peroxide alone in subinhibitory concentrations. These data support the importance of oxidative products in general and the myeloperoxidase system in particular in damage to hyphae by neutrophils. Cationic proteins may also contribute significantly to neutrophil-mediated damage to R. oryzae hyphae. PMID:6292103

Diamond, Richard D.; Clark, Robert A.

1982-01-01

75

Assessment of genotoxicity of catecholics using impedimetric DNA-biosensor.  

PubMed

The potential toxicity of catecholics is a big concern, because the catechol-derived semiquinone radical after the oxidation of catechol (CA) can donate an H-atom to generate quinone, and during this process a superoxide anion radical may be produced. Considering the fact that catecholics are highly consumed in our daily life and some drugs also contain one or more CA moieties, we speculate that CA's toxicity might not be insurmountable. Therefore, finding approaches to investigate catecholics potential toxicity is of great significance. Here in, an electrochemical protocol for direct monitoring of genotoxicity of catecholics is described. CA encapsulated on MWCNTs (CA@MWCNT) through continuous cyclic voltammetric on the surface of pencil graphite electrode (PGE). Subsequently, a DNA functionalized biosensor (DNA/CA@MWCNT/PGE) was prepared and characterized for the detection and the investigation of DNA damage induced by radicals generated from catecholics. The change in the charge transfer resistance (Rct) after the incubation of the DNA biosensor in the damaging solution for a certain time was used as an indicator for DNA damage. Incubation of DNA-modified electrode with CA solution containing Cu(II), Cr(VI) and Fe(III) has been shown to result in oxidative damage to the DNA and change in the electrochemical properties. It was found that the presence of Cu(II), Cr(VI) and Fe(III) in solution caused damage to DNA. The inhibitory effect of glutathione and plumbagin on the CA-mediated DNA damage has also been investigated using the biosensor. The minimum concentration of the metal ions for CA induced DNA damage was investigated. Recognition of suitable matrixes for CA-mediated DNA damage can be assessed using proposed DNA biosensor. Such direct monitoring of the DNA damage holds great promise for designing new biosensors with modification of the biosensor with different damaging agents. PMID:24121207

Ensafi, Ali A; Amini, Maryam; Rezaei, B

2014-03-15

76

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

77

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

78

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

79

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

80

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

81

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

82

Acidovorax oryzae Catheter-Associated Bloodstream Infection.  

PubMed

Acidovorax oryzae is a bacterium that has never before been reported as pathogenic in human subjects. Here we describe the first case of a successfully treated A. oryzae catheter-associated bloodstream infection in an immunocompetent patient prior to heart transplantation. PMID:25275006

Orsborne, Christopher; Hardy, Alison; Isalska, Barbara; Williams, Simon G; Muldoon, Eavan G

2014-12-01

83

A Novel Class of Gibberellin 2-Oxidases Control Semidwarfism, Tillering, and Root Development in Rice  

Microsoft Academic Search

Gibberellin 2-oxidases (GA2oxs) regulate plant growth by inactivating endogenous bioactive gibberellins (GAs). Two classes of GA2oxs inactivate GAs through 2b-hydroxylation: a larger class of C19 GA2oxs and a smaller class of C20 GA2oxs. In this study, we show that members of the rice (Oryza sativa) GA2ox family are differentially regulated and act in concert or individually to control GA levels

Shuen-Fang Lo; Show-Ya Yang; Ku-Ting Chen; Yue-Ie Hsing; Jan A. D. Zeevaart; Liang-Jwu Chen; S.-M. Yu

2008-01-01

84

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

Microsoft Academic Search

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°C in batch cultures is growth-associated and is enhanced in the presence of 160 ?M CuSO4.5 H2O and 3 mM gallic acid. The highest enzyme activity is observed at pH 7.5 and 65°C, on catechol. When

Z. B. Ögel; Y. Yüzügüllü; S. Mete; U. Bakir; Y. Kaptan; D. Sutay; A. S. Demir

2006-01-01

85

Cholesterol oxidase: physiological functions  

PubMed Central

An important aspect of catalysis by cholesterol oxidase (3?-hydroxysteroid oxidase) is the nature of its association with the lipid bilayer that contains the sterol substrate. Efficient catalytic turnover is affected by the association of the protein with the membrane as well as the solubility of the substrate in the lipid bilayer. In this review, the binding of cholesterol oxidase to the lipid bilayer, its turnover of substrates presented in different physical environments, and how these conditions affect substrate specificity are discussed. The physiological functions of the enzyme in bacterial metabolism, pathogenesis, and macrolide biosynthesis are reviewed in this context. PMID:19843168

Kreit, Joseph; Sampson, Nicole S.

2009-01-01

86

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

87

Reactive oxygen species production by catechol stabilized copper nanoparticles  

NASA Astrophysics Data System (ADS)

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

Chen, Cheng; Ahmed, Ishtiaq; Fruk, Ljiljana

2013-11-01

88

Simultaneous Detection of Xanthomonas oryzae pv. oryzae and X. oryzae pv. oryzicola in Rice Seed Using a Padlock Probe-Based Assay.  

PubMed

ABSTRACT Based on 16S-23S internal transcribed spacer ribosomal DNA sequence data, two padlock probes (PLPs), P-Xoo and P-Xoc, were designed and tested to detect Xanthomonas oryzae pv. oryzae and X. oryzae pv. oryzicola, respectively. These PLPs were combined with dot-blot hybridization to detect X. oryzae pv. oryzae and X. oryzae pv. oryzicola individually in rice seed. Using this technique, a detection sensitivity of 1 pg of X. oryzae pv. oryzae genomic DNA was observed. The technique also facilitated the detection of X. oryzae pv. oryzae in rice seedlots with 2% artificially infested seed. With regards to X. oryzae pv. oryzicola a detection threshold of 1 pg genomic DNA was observed and the pathogen was successful detected in rice seedlots with 0.2% artificially infested seed. The PLP assays detected X. oryzae pv. oryzae and X. oryzae pv. oryzicola in 39.3% (13 of 33) and 21.3% (10 of 47) of naturally infested commercial rice seedlots, respectively. In contrast, conventional polymerase chain reaction using OSF1/OSR1 and XoocF/XoocR primers sets detected X. oryzae pv. oryzae and X. oryzae pv. oryzicola in 9.1% (3 of 33) and 8.5% (4 of 47) of the same rice seedlots, respectively. We also detected both pathogens simultaneously in two seedlots, which successfully proved that PLPs (P-Xoo and P-Xoc) combined with reverse dotblot hybridization can be used to simultaneously detect multiple pathogens in naturally infested commercial rice seedlots. This approach has the potential to be an important tool for detecting multiple pathogens in seed and thereby preventing the spread of important pathogens. PMID:25207482

Tian, Yanli; Zhao, Yuqiang; Xu, Rui; Liu, Fengquan; Hu, Baishi; Walcott, R R

2014-10-01

89

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. PMID:19828030

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

2009-01-01

90

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

PubMed

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

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

2012-10-15

91

Catechol derivatives inhibit the fibril formation of amyloid-? peptides  

Microsoft Academic Search

The inhibition of fibril formation of amyloid ? proteins (A?) would be attractive therapeutic targets for the treatment of Alzheimer's disease (AD). Dopamine (DA) and other catechol derivatives were used as inhibitory factors for A? fibril formation. The fibril formation of A? was monitored by Thioflavin T fluorescence, a transmission electron microscopy (TEM) and a total internal reflection fluorescence microscopy

Vu Thi Huong; Toshinori Shimanouchi; Naoya Shimauchi; Hisashi Yagi; Hiroshi Umakoshi; Yuji Goto; Ryoichi Kuboi

2010-01-01

92

Polyphosphorylated triphenylenes: synthesis, crystal structure, and selective catechol recognition.  

PubMed

Designed as a multivalent hydrogen bond acceptor, new receptors, Discopus 1a,b, were built from a triphenylene core surrounded by six (diaryl)phosphinate groups. An efficient synthesis was developed to prepare these elaborated structures in a high overall yield. The X-ray structure of receptor 1b showed strong cooperative hydrogen bonds with two water molecules and intermolecular CH-pi contacts. In chloroform, Discopus 1a,b displayed recognition properties toward dihydroxybenzenes, selectively forming complexes with catechol derivatives 4a-c in a 1:2 (host:guest) stoichiometry. According to NMR and microcalorimetry titrations, association constants were found in the 30-2837 M(-1) range, which were larger than those reported for curvated catechol receptors (14-120 M(-1)). Interestingly, Discopus present two distinct catechol binding sites. Weak hydrogen bonding between host phosphinates and guest hydroxyl groups was shown by infrared spectroscopy and (31)P NMR. Molecular dynamics simulations and recognition experiments suggested that a stronger hydrogen bond assisted by a pi-interaction between the Discopus core and one catechol molecule could exist within the 1:2 complex. PMID:19049263

Givelet, Cécile; Tinant, Bernard; Van Meervelt, Luc; Buffeteau, Thierry; Marchand-Geneste, Nathalie; Bibal, Brigitte

2009-01-16

93

Characterization of polyphenol oxidase activity in Ataulfo mango.  

PubMed

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

Cheema, Summervir; Sommerhalter, Monika

2015-03-15

94

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

95

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

96

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

2010-09-01

97

Phylogenomic Relationships of Rice Oxalate Oxidases to the Cupin Superfamily and Their Association with Disease Resistance QTL  

Microsoft Academic Search

Rice oxalate oxidase genes (OXO) may play a role in resistance to Magnaporthe oryzae. Genome analyses showed four tandemly duplicated OXO genes, OsOXO1–OsOXO4, which mapped to a blast resistance QTL in chromosome 3. These genes have >90% nucleotide and amino acid identity, but they\\u000a have unique gene structures, conserved motifs, and phylogeny compared to the 70 other members of the

Maria Gay C. Carrillo; Paul H. Goodwin; Jan E. Leach; Hei Leung; Casiana M. Vera Cruz

2009-01-01

98

A catechol biosensor based on electrospun carbon nanofibers  

PubMed Central

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

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

2014-01-01

99

Brain catechol synthesis - Control by brain tyrosine concentration  

NASA Technical Reports Server (NTRS)

Brain catechol synthesis was estimated by measuring the rate at which brain dopa levels rose following decarboxylase inhibition. Dopa accumulation was accelerated by tyrosine administration, and decreased by treatments that lowered brain tyrosine concentrations (for example, intraperitoneal tryptophan, leucine, or parachlorophenylalanine). A low dose of phenylalanine elevated brain tyrosine without accelerating dopa synthesis. Our findings raise the possibility that nutritional and endocrine factors might influence brain catecholamine synthesis by controlling the availability of tyrosine.

Wurtman, R. J.; Larin, F.; Mostafapour, S.; Fernstrom, J. D.

1974-01-01

100

Purification and Characterization of Streptomyces griseus Catechol O-Methyltransferase  

PubMed Central

A soluble (100,000 × g supernatant) methyltransferase catalyzing the transfer of the methyl group of S-adenosyl-l-methionine to catechols was present in cell extracts of Streptomyces griseus. A simple, general, and rapid catechol-based assay method was devised for enzyme purification and characterization. The enzyme was purified 141-fold by precipitation with ammonium sulfate and successive chromatography over columns of DEAE-cellulose, DEAE-Sepharose, and Sephacryl S-200. The purified cytoplasmic enzyme required 10 mM magnesium for maximal activity and was catalytically optimal at pH 7.5 and 35°C. The methyltransferase had an apparent molecular mass of 36 kDa for both the native and denatured protein, with a pI of 4.4. Novel N-terminal and internal amino acid sequences were determined as DFVLDNEGNPLENNGGYXYI and RPDFXLEPPYTGPXKARIIRYFY, respectively. For this enzyme, the Km for 6,7-dihydroxycoumarin was 500 ± 21.5 ?M, and that for S-adenosyl-l-methionine was 600 ± 32.5 ?M. Catechol, caffeic acid, and 4-nitrocatechol were methyltransferase substrates. Homocysteine was a competitive inhibitor of S-adenosyl-l-methionine, with a Ki of 224 ± 20.6 ?M. Sinefungin and S-adenosylhomocysteine inhibited methylation, and the enzyme was inactivated by Hg2+, p-chloromercuribenzoic acid, and N-ethylmaleimide. PMID:11055938

Dhar, Kajari; Rosazza, John P. N.

2000-01-01

101

Partial purification and characterization of polyphenol oxidase from persimmon.  

PubMed

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

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

2014-08-15

102

Spectrophotometric determination of germanium with Catechol Violet and cetyltrimethylammonium bromide.  

PubMed

A ternary complex between germanium, Catechol Violet (CV) and cetyltrimethylanunoniuni bromide is proposed for the determination of germanium. The stoichiometric ratio Ge:CV is 1:2. Beer's law is obeyed from 0.1 to 1.0 ppm of Ge. The method is highly selective. Interference from Sn(IV), Fe(III), Bi(III), Cr(VI), Mo(VI), V(V) and Sb(III) in mg amounts is eliminated by extracting the germanium into carbon tetrachloride from 9M HC1 and then stripping into water before the photometric determination. PMID:18960953

Leong, C L

1971-08-01

103

Unusual behavior in the first excited state lifetime of catechol  

E-print Network

We are presenting vibrationally selective pump-probe measurements of the first electronic excited-state (pp*) lifetime of jet-cooled neutral catechol (1,2-dihydroxybenzene). The lifetime of the 0-0 transition is very short (7 ps) as rationalized by the small pp*/psigma* gap calculated. However the lifetimes implying higher out-of-plane vibrational levels are longer (~11 ps). This emphasizes the role of the out-of-plane vibration in the pp*/psigma* coupling not only in its nature but also in the number of quanta

Weiler, Martin; Féraud, Géraldine; Ishiuchi, Shun-Ichi; Dedonder, Claude; Jouvet, Christophe; Fujii, Masaaki

2014-01-01

104

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

105

Catalytic Solvolytic and Hydrolytic Degradation of Toxic Methyl Paraoxon with La(catecholate)-Functionalized Porous Organic  

E-print Network

for nerve agents. KEYWORDS: porous organic polymers, catechol, catalysis, organophosphates, lanthanum with promising applications in gas storage,1-7 chemical separation,3,8-11 and heterogeneous catalysis.12-based nerve agents,19,24 we reasoned that a Lewis-acidic metal ion bound inside a catechol-functionalized POP

106

Genome sequence and rapid evolution of the rice pathogen Xanthomonas oryzae pv. oryzae PXO99A  

PubMed Central

Background Xanthomonas oryzae pv. oryzae causes bacterial blight of rice (Oryza sativa L.), a major disease that constrains production of this staple crop in many parts of the world. We report here on the complete genome sequence of strain PXO99A and its comparison to two previously sequenced strains, KACC10331 and MAFF311018, which are highly similar to one another. Results The PXO99A genome is a single circular chromosome of 5,240,075 bp, considerably longer than the genomes of the other strains (4,941,439 bp and 4,940,217 bp, respectively), and it contains 5083 protein-coding genes, including 87 not found in KACC10331 or MAFF311018. PXO99A contains a greater number of virulence-associated transcription activator-like effector genes and has at least ten major chromosomal rearrangements relative to KACC10331 and MAFF311018. PXO99A contains numerous copies of diverse insertion sequence elements, members of which are associated with 7 out of 10 of the major rearrangements. A rapidly-evolving CRISPR (clustered regularly interspersed short palindromic repeats) region contains evidence of dozens of phage infections unique to the PXO99A lineage. PXO99A also contains a unique, near-perfect tandem repeat of 212 kilobases close to the replication terminus. Conclusion Our results provide striking evidence of genome plasticity and rapid evolution within Xanthomonas oryzae pv. oryzae. The comparisons point to sources of genomic variation and candidates for strain-specific adaptations of this pathogen that help to explain the extraordinary diversity of Xanthomonas oryzae pv. oryzae genotypes and races that have been isolated from around the world. PMID:18452608

Salzberg, Steven L; Sommer, Daniel D; Schatz, Michael C; Phillippy, Adam M; Rabinowicz, Pablo D; Tsuge, Seiji; Furutani, Ayako; Ochiai, Hirokazu; Delcher, Arthur L; Kelley, David; Madupu, Ramana; Puiu, Daniela; Radune, Diana; Shumway, Martin; Trapnell, Cole; Aparna, Gudlur; Jha, Gopaljee; Pandey, Alok; Patil, Prabhu B; Ishihara, Hiromichi; Meyer, Damien F; Szurek, Boris; Verdier, Valerie; Koebnik, Ralf; Dow, J Maxwell; Ryan, Robert P; Hirata, Hisae; Tsuyumu, Shinji; Won Lee, Sang; Ronald, Pamela C; Sonti, Ramesh V; Van Sluys, Marie-Anne; Leach, Jan E; White, Frank F; Bogdanove, Adam J

2008-01-01

107

Mapping the conformational space accessible to catechol-O-methyltransferase  

PubMed Central

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

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

2014-01-01

108

Sensitive detection of Xanthomonas oryzae Pathovars oryzae and oryzicola by loop-mediated isothermal amplification.  

PubMed

Molecular diagnostics for crop diseases can enhance food security by enabling the rapid identification of threatening pathogens and providing critical information for the deployment of disease management strategies. Loop-mediated isothermal amplification (LAMP) is a PCR-based tool that allows the rapid, highly specific amplification of target DNA sequences at a single temperature and is thus ideal for field-level diagnosis of plant diseases. We developed primers highly specific for two globally important rice pathogens, Xanthomonas oryzae pv. oryzae, the causal agent of bacterial blight (BB) disease, and X. oryzae pv. oryzicola, the causal agent of bacterial leaf streak disease (BLS), for use in reliable, sensitive LAMP assays. In addition to pathovar distinction, two assays that differentiate X. oryzae pv. oryzae by African or Asian lineage were developed. Using these LAMP primer sets, the presence of each pathogen was detected from DNA and bacterial cells, as well as leaf and seed samples. Thresholds of detection for all assays were consistently 10(4) to 10(5) CFU ml(-1), while genomic DNA thresholds were between 1 pg and 10 fg. Use of the unique sequences combined with the LAMP assay provides a sensitive, accurate, rapid, simple, and inexpensive protocol to detect both BB and BLS pathogens. PMID:24837384

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

2014-08-01

109

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

PubMed Central

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 comprised of a single, 4 941 439 bp, circular chromosome that is G + C rich (63.7%). The genome includes 4637 open reading frames (ORFs) of which 3340 (72.0%) could be assigned putative function. Orthologs for 80% of the predicted Xoo genes were found in the previously reported X.axonopodis pv. citri (Xac) and X.campestris pv. campestris (Xcc) genomes, but 245 genes apparently specific to Xoo were identified. Xoo genes likely to be associated with pathogenesis include eight with similarity to Xanthomonas avirulence (avr) genes, a set of hypersensitive reaction and pathogenicity (hrp) genes, genes for exopolysaccharide production, and genes encoding extracellular plant cell wall-degrading enzymes. The presence of these genes provides insights into the interactions of this pathogen with its gramineous host. PMID:15673718

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

2005-01-01

110

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

111

Purification of active recombinant trypanosome alternative oxidase  

Microsoft Academic Search

Trypanosome alternative oxidase (TAO) is the terminal oxidase of the respiratory chain in long slender bloodstream forms of African trypanosomes. TAO is a cytochrome-independent, cyanide-insensitive quinol oxidase. These characteristics are distinct from those of the bacterial quinol oxidases, proteins that belong to the heme-copper terminal oxidase superfamily. The inability to purify stable TAO has severely hampered biochemical studies of the

Coichi Nihei; Yoshihisa Fukai; Keisuke Kawai; Arihiro Osanai; Yoshisada Yabu; Takashi Suzuki; Nobuo Ohta; Nobuko Minagawa; Kazuo Nagai; Kiyoshi Kita

2003-01-01

112

[Isolation and characteristics of micromycetes--producers of neutral phenol oxidase from trophic soil with a high level of dioxins].  

PubMed

Samples of South Vietnamese soils intensely treated with Agent Orange defoliant were tested for the presence of fungi and actinomycetes with elevated phenol oxidase activity. As a result, fast-growing non-sporulating strain producing neutral phenol oxidases was isolated and identified as Mycelia sterilia INBI 2-26. The strain formed extracellular phenol oxidases during surface growth on liquid medium in the presence of guayacol and copper sulfate, as well as during submerged cultivation in liquid medium containing wheat bran and sugar beet pulp. Isoelectric focusing of cultural liquid has revealed two major catechol oxidases (PO1 and PO2) with pI 3.5 and 8, respectively. The enzymes were purified by ultrafiltration, ion exchange chromatography and exclusion HPLC. Both were stable between pH 3 and 8. At pH 8 and 40 degrees C they retained at least 50% of activity after incubation for 50 h. At 50 degrees C PO2 was more stable and retained 40% of activity after 50 h, whereas PO1 was inactivated in 3-6 h. The pH optimums for PO1 and PO2 towards catechol were equal to 6 and 6.5, and the Km values were 1.5 +/- 0.35 and 1.25 +/- 0.2 mM, respectively. PO1 and PO2 most optimally oxidized 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) at pH 3 with Km values 1.6 +/- 0.18 and 0.045 +/- 0.01 mM, respectively, but displayed no activity towards tyrosine. The PO2 absorbance spectrum had a peak at 600 nm, thus indicating the enzyme to be a member of the laccase family. PMID:10994189

Vasil'chenko, L G; Koroleva, O V; Stepanova, E V; Landesman, E O; Rabinovich, M L

2000-01-01

113

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

114

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

115

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

PubMed Central

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

Pandey, Alok; Sonti, Ramesh V.

2010-01-01

116

Detection of Xanthomonas oryzae pv. oryzae in artificially inoculated and naturally infected rice seeds and plants by molecular techniques  

Microsoft Academic Search

A polymerase chain reaction (PCR) technique was developed for detecting the presence of Xanthomonas oryzae pv. oryzae, the bacterial leaf blight (BLB) pathogen in rice seed and for studying the transmission of this bacterium from seed to plant. Primers TXT and TXT4R from an insertion sequence (IS1113) of the pathogen were used to amplify a 964-bp DNA fragment. A combined

N. Sakthivel; C. N. Mortensen; S. B. Mathur

2001-01-01

117

Purification and characterization of polyphenol oxidase from fresh ginseng  

PubMed Central

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

2013-01-01

118

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

119

Heterogeneous Reactions of Surface-Adsorbed Catechol: A Comparison of Tropospheric Aerosol Surrogates  

NASA Astrophysics Data System (ADS)

Surface-adsorbed organics can alter the chemistry of tropospheric solid-air interfaces, such as aerosol and ground level surfaces, thereby impacting photochemical cycles and altering aerosol properties. The nature of the surface can also influence the chemistry of the surface-adsorbed organic. We employed diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to monitor the adsorption of gaseous catechol on several tropospheric aerosol surrogates and to investigate the subsequent reactivity of adsorbed-catechol with nitrogen dioxide and, in separate preliminary experiments, ozone. Graphite, kaolinite, and sodium halide (NaF, NaCl, NaBr) powders served as carbonaceous, mineral and sea salt aerosol surrogates, respectively. Broad OH stretching bands for adsorbed catechol shifted to lower wavenumber with peak frequencies following the trend NaBr > NaCl > NaF ? kaolinite, consistent with the increasing basicity of the halide anions and basic Brřnsted sites on kaolinite. The dark heterogeneous reaction of NO2 with NaCl-adsorbed catechol at relative humidity (RH) <2% promoted nitration forming 4-nitrocatechol and oxidation forming 1,2-benzoquinone and the ring cleavage product muconic acid, with product yields of 88%, 8%, and 4%, respectively. 4-Nitrocatechol was the dominant product for catechol adsorbed on NaF and kaolinite, while NaBr-adsorbed catechol produced less 4-nitrocatechol and more 1,2-benzoquinone and muconic acid. For all three sodium halides, the reactions of NO2 with adsorbed catechol were orders of magnitude faster than between NO2 and each NaX substrate. 4-Nitrocatechol rates and product yields were consistent with the relative ability of each substrate to enhance the deprotonated nature of adsorbed-catechol. Increasing the relative humidity caused the rate of each product channel to decrease and also altered the product branching ratios. Most notably, 1,2-benzoquinone formation decreased significantly even at 13% RH. The dramatic reactivity of surface-adsorbed catechol contrasts prior observations which found thin films of pure catechol unreactive with NO2, indicating that thin films do not always serve as reliable models for surface-adsorbed species.

Hinrichs, R. Z.; Woodill, L. A.

2009-12-01

120

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

PubMed

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

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

2013-06-01

121

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

2013-05-01

122

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

2011-01-01

123

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

PubMed

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

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

2014-01-01

124

Characterization of catechol 2,3-dioxygenase from Planococcus sp. strain S5 induced by high phenol concentration.  

PubMed

This study aimed at characterization of a new catechol 2,3-dioxygenase isolated from a Gram-positive bacterium able to utilize phenol as the sole carbon and energy source. Planococcus sp. strain S5 grown on 1 or 2 mM phenol showed activity of both a catechol 1,2- and catechol 2,3-dioxygenase while at a higher concentrations of phenol only catechol 2,3-dioxygenase activity was observed. The enzyme was optimally active at 60°C and pH 8.0. Kinetic studies showed that the K(m) and V(max) of the enzyme were 42.70 µM and 329.96 mU, respectively. The catechol 2,3-dioxygenase showed the following relative meta-cleavage activities for various catechols tested: catechol (100%), 3-methylcatechol (13.67%), 4-methylcatechol (106.33%) and 4-chlorocatechol (203.80%). The high reactivity of this enzyme towards 4-chlorocatechol is different from that observed for other catechol 2,3-dioxygenases. Nucleotide sequencing and homology search revealed that the gene encoding the S5 catechol 2,3-dioxygenase shared the greatest homology with the known genes encoding isoenzymes from Gram-negative Pseudomonas strains. PMID:22826823

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

2012-01-01

125

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

126

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

127

NADPH oxidase: a universal oxygen sensor?  

Microsoft Academic Search

NADPH oxidase is classically regarded as a key enzyme of neutrophils, where it is involved in the pathogenic production of reactive oxygen species. However, NADPH oxidase-like enzymes have recently been identified in non-neutrophil cells, supporting a separate role for NADPH-oxidase derived oxygen species in oxygen sensitive processes. This article reviews the current literature surrounding the potential role of NADPH oxidase

Richard D Jones; John T Hancock; Alyn H Morice

2000-01-01

128

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

PubMed Central

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

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

1995-01-01

129

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

130

21 CFR 173.130 - Carbohydrase derived from Rhizopus oryzae.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

131

21 CFR 173.130 - Carbohydrase derived from Rhizopus oryzae.  

Code of Federal Regulations, 2011 CFR

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

2011-04-01

132

21 CFR 173.130 - Carbohydrase derived from Rhizopus oryzae.  

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

2014-04-01

133

21 CFR 173.130 - Carbohydrase derived from Rhizopus oryzae.  

Code of Federal Regulations, 2012 CFR

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

2012-04-01

134

Draft Genome Sequence of Lactobacillus oryzae Strain SG293T  

PubMed Central

We report the 1.86-Mb draft genome and annotation of Lactobacillus oryzae SG293T isolated from fermented rice grains. This genome information may provide further insights into the mechanisms underlying the fermentation of rice grains. PMID:25169865

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

2014-01-01

135

Improving Pharmaceutical Protein Production in Oryza sativa  

PubMed Central

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

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

2013-01-01

136

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. PMID:12461173

Linares, Olga F.

2002-01-01

137

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

138

Effect of ?-cyclodextrin on intra and intermolecular Michael addition of some catechol derivatives.  

PubMed

The oxidation reactions of catechol, dopamine and epinephrine have been studied in the absence and presence of N-methylaniline by UV-Vis. Spectrophotometry. A variety of reaction pathways (inter and intramolecular reactions) that followed by this oxidation have been observed depending on the nature of catechol derivatives. The observed homogeneous rate constants of the reactions were estimated by fitting the absorption time profiles for each reaction. The effect of ?-cyclodextrin and its inclusion complex has also been studied on the chosen reactions. The formation constants of the complexes of catechol, dopamine and epinephrine with ?-cyclodextrin as well as the rate constants of the reactions of free and complexed forms have been obtained by fitting the absorption-time spectra to a proposed kinetic-equilibrium model. PMID:24096065

Khalafi, Lida; Rafiee, Mohammad; Fathi, Sahar

2014-01-24

139

Molecularly-imprinted solid phase extraction of catechol from aqueous effluents for its selective determination by differential pulse voltammetry  

Microsoft Academic Search

A polymeric sorbent based on molecular imprinting technology has been synthesized and applied to selectively extract catechol from water samples with subsequent determination by differential pulse voltammetry (DPV). The non-covalent polymer was prepared by bulk polymerization using catechol and 4-vinylpyridine as template and monomer, respectively. The effect of the flow and chemical variables associated to the performance of the solid

César Ricardo Teixeira Tarley; Lauro Tatsuo Kubota

2005-01-01

140

SPECTROSCOPIC STUDIES OF THE ANAEROBIC ENZYME-SUBSTRATE COMPLEX OF CATECHOL 1,2-DIOXYGENASE  

PubMed Central

The basis of the respective regiospecificities of intradiol and extradiol dioxygenase is poorly understood and may be linked to the protonation state of the bidentate-bound catechol in the enzyme:substrate complex. Previous ultraviolet resonance Raman (UVRR) and UV-visible (UV-vis) difference spectroscopic studies demonstrated that in extradiol dioxygenases, the catechol is bound to the Fe(II) as a monoanion. In this study, we use the same approaches to demonstrate that in catechol 1,2-dioxygenase (C12O), an intradiol enzyme, the catechol binds to the Fe(III) as a dianion. Specifically, features at 290 nm and 1550 cm?1 in the UV-vis and UVRR difference spectra, respectively, are assigned to dianionic catechol based on spectra of the model compound, ferric tris(catecholate). The UVRR spectroscopic band assignments are corroborated by density functional theory (DFT) calculations. In addition, negative features at 240 nm in UV-vis difference spectra and at 1600, 1210, and 1175 cm?1 in UVRR difference spectra match those of a tyrosinate model compound, consistent with protonation of the axial tyrosinate ligand when it is displaced from the ferric ion coordination sphere upon substrate binding. The DFT calculations ascribe the asymmetry of the bound dianionic substrate to the trans donor effect of an equatorially ligated tyrosinate ligand. In addition, the computations suggest that trans donation from the tyrosinate ligand may facilitate charge-transfer from the substrate to yield the iron-bound semiquinone transition state, which is capable of reacting with dioxygen. In illustrating the importance of ligand trans effects in a biological system, the current study demonstrates the power of combining difference UVRR and optical spectroscopies to probe metal ligation in solution. PMID:16316234

Horsman, Geoff P.; Jirasek, Andrew; Vaillancourt, Frederic H.; Barbosa, Christopher J.; Jarzecki, Andrzej A.; Xu, Changliang; Mekmouche, Yasmina; Spiro, Thomas G.; Lipscomb, John D.; Blades, Michael W.; Turner, Robin F.B.; Eltis, Lindsay D.

2008-01-01

141

Mutagenesis of 18 type III effectors reveals virulence function of XopZ(PXO99) in Xanthomonas oryzae pv. oryzae.  

PubMed

Xanthomonas oryzae pv. oryzae depends on a type III secretion system (T3SS) to translocate effectors into host cells for its ability to cause bacterial blight of rice. All type III (T3) effectors with known function in X. oryzae pv. oryzae belong to a family of transcription activator-like (TAL) effectors. However, other, non-TAL-related effector genes are present in the genome, although their role in virulence and their mode of action have yet to be elucidated. Here, we report the generation of mutants for 18 non-TAL T3 effector genes and the identification of one that contributes to the virulence of strain PXO99(A). XopZ(PXO99) encodes a predicted 1,414-amino-acid protein of unknown function. PXO99(A) contains two identical copies of the gene due to a duplication of 212 kb in the genome. Strains with knockout mutations of one copy of XopZ(PXO99) did not exhibit any visible virulence defect. However, strains with mutations in both copies of XopZ(PXO99) displayed reduced virulence in terms of lesion length and bacterial multiplication compared with PXO99(A). The introduction of one genomic copy of XopZ(PXO99) restores the mutant to full virulence. Transient expression of XopZ(PXO99) in Nicotiana benthamiana leaves suppresses host basal defense, which is otherwise induced by a T3SS mutant of PXO99(A), suggesting a role for XopZ(PXO99) in interfering with host innate immunity during X. oryzae pv. oryzae infection. XopZ(PXO99)-related genes are found in all Xanthomonas spp. whose genomic sequences have been determined, suggesting a conserved role for this type of effector gene in pathogenesis of Xanthomonas spp. Our results indicate that XopZ(PXO99) encodes a novel T3 effector and contributes virulence to X. oryzae pv. oryzae strains for bacterial blight of rice. PMID:20521952

Song, Congfeng; Yang, Bing

2010-07-01

142

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

2013-12-01

143

Measurement of haplotypic variation in Xanthomonas oryzae pv. oryzae within a single field by rep-PCR and RFLP analyses  

SciTech Connect

The haplotypic variation of Xanthomonas oryzae pv. oryzae in a farmer;s field that had endemic bacterial blight in the Philippines was evaluated at a single time. The genomic structure of the field population was analyzed by repetitive sequence-based polymerase chain reaction with oligonucleotide primers corresponding to interspersed repeated sequences in prokaryotic genomes and restriction fragment length polymorphism (RFLP) with the insertion sequence IS1113. The techniques and specific probes and primers were selected because they grouped consistently into the same lineages a set of 30 selected X. oryzae pv. oryzae strains that represented the four distinct RFLP lineages found in the Philippines did. Strains (155) were systematically collected from a field planted to rice cv. Sinandomeng, which is susceptible to the indigenous pathogen population. Two of the four Philippine lineages, B and C, which included race 2 and races 3 and 9, respectively, were detected in the field. Lineage C was the predominant population (74.8%). The haplotypic diversities of 10 of the 25 blocks were significantly greater than the total haplotypic diversity of the collection in the entire field; however, between individual blocks the haplotypic diversities were not significantly different. Haplo-types from both lineages were distributed randomly across the field. Analysis of genetic diversity at the microgeographic scale provided insights into the finer scale of variation of X. oryzae pv. oryzae, which are useful in designing experiments to study effects of host resistance on the population structure of the bacterial blight pathogen. 46 refs., 4 figs., 2 tabs.

Vera Cruz, C.M.; Leach, J.E. [Kansas State Univ., Manhattan, KS (United States); Ardales, E.Y.; Talag, J. [International Rice Research Institute, Manila (Philippines)] [and others

1996-12-01

144

Comparative effects of Saccharomyces cerevisiae and Aspergillus oryzae on rumen fermentations  

E-print Network

Comparative effects of Saccharomyces cerevisiae and Aspergillus oryzae on rumen fermentations F Aubière Cedex, France Saccharomyces cerevisiae (SC) and Aspergillus oryzae (AO) have both been proposed

Boyer, Edmond

145

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

146

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

DOEpatents

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

Fish, R.H.

1987-04-21

147

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

148

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. PMID:16349193

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

1994-01-01

149

Catechol-O-methyltransferase in complex with substituted 3'-deoxyribose bisubstrate inhibitors.  

PubMed

The biological activity of catechol neurotransmitters such as dopamine in the synapse is modulated by transporters and enzymes. Catechol-O-methyltransferase (COMT; EC 2.1.1.6) inactivates neurotransmitters by catalyzing the transfer of a methyl group from S-adenosylmethionine to catechols in the presence of Mg˛?. This pathway also inactivates L-DOPA, the standard therapeutic for Parkinson's disease. Depletion of catechol neurotransmitters in the prefrontal cortex has been linked to schizophrenia. The inhibition of COMT therefore promises improvements in the treatment of these diseases. The concept of bisubstrate inhibitors for COMT has been described previously. Here, ribose-modified bisubstrate inhibitors were studied. Three high-resolution crystal structures of COMT in complex with novel ribose-modified bisubstrate inhibitors confirmed the predicted binding mode but displayed subtle alterations at the ribose-binding site. The high affinity of the inhibitors can be convincingly rationalized from the structures, which document the possibility of removing and/or replacing the ribose 3'-hydroxyl group and provide a framework for further inhibitor design. PMID:22349227

Ellermann, Manuel; Lerner, Christian; Burgy, Guillaume; Ehler, Andreas; Bissantz, Caterina; Jakob-Roetne, Roland; Paulini, Ralph; Allemann, Oliver; Tissot, Heloďse; Grünstein, Dan; Stihle, Martine; Diederich, Francois; Rudolph, Markus G

2012-03-01

150

Two Genomic Regions Involved in Catechol Siderophore Production by Erwinia carotovora.  

PubMed

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. PMID:16349193

Bull, C T; Ishimaru, C A; Loper, J E

1994-02-01

151

High propylene/propane adsorption selectivity in a copper(catecholate)-decorated porous organic  

E-print Network

High propylene/propane adsorption selectivity in a copper(catecholate)-decorated porous organic and propane isotherms measured at ambient temperatures and ideal adsorption solution theory (IAST) calculations revealed increasing propylene/propane selectivities with increasing pressures. The eld of highly

152

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. 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.

2012-01-01

153

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

E-print Network

Direct biocatalytic synthesis of functionalized catechols: a green alternative to traditional species. The yields and the ease of preparation of these compounds are compared with traditional chemical, see ref. 9) are calculated and compared with those obtained by traditional methods to indicate

Hudlicky, Tomas

154

Transformation of phenol, catechol, guaiacol and syringol exposed to sodium hypochlorite  

Microsoft Academic Search

Germs, xenobiotics and organic matter that influence the colour, turbidity and organoloeptic properties of water are removed by chlorination. Unfortunately, chlorine oxidants including sodium hypochlorite, used in water treatment induce processes that partly convert the treated compounds to unwanted chlorinated derivatives. The purpose of this work was to analyse the efficiency of transformation of phenol, catechol, guaiacol and syringol exposed

Jaromir Micha?owicz; Wirgiliusz Duda; Jadwiga Stufka-Olczyk

2007-01-01

155

Conductivity-Based Catechol Sensor Using Tyrosinase Immobilized in Porous Silicon  

Microsoft Academic Search

A conductivity-based catechol biosensor was developed using porous silicon as an immobilization matrix for enzyme tyrosinase. The enzyme was extracted from plant source Amorphophallus companulatus and immobilized in an electrochemically etched surface of p-type silicon. The presence of enzyme in a porous structure and the retention of enzyme activity were confirmed by scanning electron microscopy and spectrophotometric studies, respectively. The

Sanket Tembe; Prajakta S. Chaudhari; S. V. Bhoraskar; S. F. D'Souza; Meena S. Karve

2008-01-01

156

Draft Genome Sequence of Aspergillus oryzae 100-8, an Increased Acid Protease Production Strain  

PubMed Central

Aspergillus oryzae is a common fungus for traditional fermentation in Asia, such as spirit, soybean paste, and soy sauce fermentation. We report the 36.7-Mbp draft genome sequence of A. oryzae 100-8 and compared it to the published genome sequence of A. oryzae 3.042. PMID:24903875

Zhao, Guozhong; Yao, Yunping; Hou, Lihua

2014-01-01

157

gltB/D mutants of Xanthomonas oryzae pv. oryzae are virulence deficient.  

PubMed

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight, a serious disease of rice. Upon clip inoculation of rice leaves, Xoo causes typical V-shaped lesions whose leading edge moves through the mid-veinal region. We have isolated a virulence deficient mutant of Xoo, referred to as BXO808 that causes limited lesions which primarily extend through the side-veinal regions of rice leaves. Functional complementation studies identified a clone, pSR19, from a cosmid genomic library that restored wild-type virulence and lesion phenotype to BXO808. Transposon mutagenesis of the pSR19 clone, marker exchange experiments, and targeted mutagenesis, revealed that the BXO808 phenotype is due to mutation in the gltB/D genes of Xoo, which encode glutamate synthase subunits ? and ?, respectively. The gltB/D mutants that were generated in this study also exhibited virulence deficiency, an altered lesion phenotype and growth deficiency on minimal medium with low levels of ammonium as a sole nitrogen source. This is the first report that mutations in the gltB/D genes of Xoo cause virulence deficiency. PMID:23995777

Pandey, Alok; Ray, Suvendra Kumar; Sonti, Ramesh V; Rajeshwari, R

2014-01-01

158

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

PubMed

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

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

2013-08-01

159

The sense and antisense expression of gibberellin 20-oxidase gene ( rga5 ) in rice and its effects on GA 1 level and agronomic traits  

Microsoft Academic Search

A gibberellin 20-oxidase generga5 was isolated by PCR from genomic DNA of rice (Oryza sativa ssp indica) cultivars ‘Aizizhan’ and ‘Nante’. Compared with the reported OsGA20ox, therga5 was partial-frame-shifted with 11 different amino acids. Then therga5 with CaMV 35S promotor and NOS terminator was inserted into the polylinker site of pCambia1301 to construct sense and antisense\\u000a gene expressing vectors pSrga5

Yuanxin Yan; Chengcai An; Li Li; Jiayu Gu; Lijiang Wang; Shuangli Mi; Zhangliang Chen

2003-01-01

160

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

161

Monoamine Oxidase Inhibitors: Clinical Review  

PubMed Central

Monoamine oxidase inhibitors (MAOIs) are effective antidepressant agents. They are increasingly and effectively used in a number of other psychiatric and non-psychiatric medical syndromes. Their potential for serious toxicity (i.e., hypertensive reaction) is far less than original reports suggest, and newer reversible substrate-specific MAOIs may offer even less toxicity. The author reviews the pharmacology, mechanism of action, clinical indications, and dosing strategies of MAOIs. The common MAOI side-effects (hypotension, weight gain, sexual dysfunction, insomnia, daytime sedation, myoclonus, and hypertensive episodes) are described and management techniques suggested. Recent clinical developments involving MAOIs are outlined. PMID:21233984

Remick, Ronald A.; Froese, Colleen

1990-01-01

162

Cyclopiazonic Acid Biosynthesis of Aspergillus flavus and Aspergillus oryzae  

PubMed Central

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

2009-01-01

163

The therapeutic potential of monoamine oxidase inhibitors  

Microsoft Academic Search

Monoamine oxidase inhibitors were among the first antidepressants to be discovered and have long been used as such. It now seems that many of these agents might have therapeutic value in several common neurodegenerative conditions, independently of their inhibition of monoamine oxidase activity. However, many claims and some counter-claims have been made about the physiological importance of these enzymes and

Dale Edmondson; Keith F. Tipton; Moussa B. H. Youdim

2006-01-01

164

Regulation of innate immunity by NADPH oxidase  

PubMed Central

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

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

2012-01-01

165

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. PMID:22912739

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

2012-01-01

166

[SERS spectra of Xanthomonas oryzae pv. Oryzae (Xoo) on nano silver film prepared by electrolysis method].  

PubMed

The nano silver film was prepared by electrolysis method using silver nitrate and polyvinyl alcohol (PVA) in deionized water as the electrolyte, with four glass slides put in the electrolyte and two silver rods dipped into the electrolyte as the anode and cathode. A direct current was applied to the rods, then the four glass slides stayed in the silver colloids. Thus the authors got the nano silver film. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were employed to detect the silver particles in the silver colloids and on the nano silver film. From the SEM we can see that the silver particles on the film formed different layers. In one layer, the distance between two particles was about 100 nm. The samples of Xanthomonas oryzae pv. Oryzae (Xoo) were 7 different kinds of bacterial blight, namely 1-YN1, 2-YN7, 3-YN11, 4-GD414, 5-SCYC6, 6-HEN11 and 7-FWJ. Because the silver particles in the colloids were aggregated on the film, there was large electromagnetic potentiation. So the SERS spectra of Xoo were perfect. The authors used the area analytical method to distinguish the different kinds of Xoo. The silver film prepared by electrolysis was cheap and active, the preparation time of the samples was short, and any normal chemistry lab can make it, which can find excellent application to detecting the Xoo in agriculture. On the other hand, this film is active on biomolecules and bioorganism, which may be a new kind of SERS fundus to explain the creation of the SERS. Further study was under way. PMID:20384127

Kang, Yi-Pu; Si, Min-Zhen; Li, Qing-Yu; Huang, Qiong; Liu, Ren-Ming

2010-02-01

167

Designer TAL effectors induce disease susceptibility and resistance to Xanthomonas oryzae pv. oryzae in rice.  

PubMed

TAL (transcription activator-like) effectors from Xanthomonas bacteria activate the cognate host genes, leading to disease susceptibility or resistance dependent on the genetic context of host target genes. The modular nature and DNA recognition code of TAL effectors enable custom-engineering of designer TAL effectors (dTALE) for gene activation. However, the feasibility of dTALEs as transcription activators for gene functional analysis has not been demonstrated. Here, we report the use of dTALEs, as expressed and delivered by the pathogenic Xanthomonas oryzae pv. oryzae (Xoo), in revealing the new function of two previously identified disease-related genes and the potential of one developmental gene for disease susceptibility in rice/Xoo interactions. The dTALE gene dTALE-xa27, designed to target the susceptible allele of the resistance gene Xa27, elicited a resistant reaction in the otherwise susceptible rice cultivar IR24. Four dTALE genes were made to induce the four annotated Xa27 homologous genes in rice cultivar Nipponbare, but none of the four induced Xa27-like genes conferred resistance to the dTALE-containing Xoo strains. A dTALE gene was also generated to activate the recessive resistance gene xa13, an allele of the disease-susceptibility gene Os8N3 (also named Xa13 or OsSWEET11, a member of sucrose efflux transporter SWEET gene family). The induction of xa13 by the dTALE rendered the resistant rice IRBB13 (xa13/xa13) susceptible to Xoo. Finally, OsSWEET12, an as-yet uncharacterized SWEET gene with no corresponding naturally occurring TAL effector identified, conferred susceptibility to the Xoo strains expressing the corresponding dTALE genes. Our results demonstrate that dTALEs can be delivered through the bacterial secretion system to activate genes of interest for functional analysis in plants. PMID:23430045

Li, Ting; Huang, Sheng; Zhou, Junhui; Yang, Bing

2013-05-01

168

The central catechol- O -methyltransferase inhibitor tolcapone increases striatal hydroxyl radical production in l DOPA\\/carbidopa treated rats  

Microsoft Academic Search

Seminary  Inhibition of catechol catechol-O-methyltransferase (COMT) in the brains of subjects treated with l-DOPA (l-3,4-dihydroxylphenylalanine) and an aromatic amino acid decarboxylase (AADC) inhibitor is suggested to cause an increase\\u000a of l-DOPA, which might lead to oxidative damage through enhanced formation of free radicals. To investigate this hypothesis, the\\u000a acute effects of two doses of the systemically administered COMT inhibitors entacapone (peripheral)

M. Gerlach; A. Y. Xiao; W. Kuhn; R. Lehnfeld; P. Waldmeier; K. H. Sontag; P. Riederer

2001-01-01

169

Changing the electrochemical behavior of catechols by means of their conversion into the corresponding ruthenium(III)–dioxolene complexes  

Microsoft Academic Search

The rather complicated electrochemical behavior, in aqueous solution, exhibited by catechol (1,2-dihydroxybenzene) and its derivatives containing carboxylate and sulphonate groups, can be conveniently controlled by means of their conversion into the corresponding blue ruthenium(III)–edta complexes (edta=ethylenedinitrilotetraacetate ligand). In the free form, the catechol species undergo a primary electrochemical oxidation process in the range of 0.3–0.6 V versus SHE, yielding quinone

Francisca N Rein; Reginaldo C Rocha; Henrique E Toma

2000-01-01

170

Multiple Promoters of Catechol-O-methyltransferase Gene Are Selectively Inactivated by CpG Hypermethylation in Endometrial Cancer  

Microsoft Academic Search

Catechol-O-methyltransferase (COMT) plays an important role in estrogen-induced cancers because COMT inactivates catechol estrogens that have cancer-promoting activities. Two promoters control the expres- sion of human COMT isoforms: membrane-bound COMT (MB-COMT) and soluble COMT (S-COMT). We hypothesize that inactivation of MB- COMT and S-COMT is important in understanding the pathogenesis of endometrial cancer. To test this hypothesis, we investigated the

Masahiro Sasaki; Masanori Kaneuchi; Noriaki Sakuragi; Rajvir Dahiya

2003-01-01

171

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. PMID:21769297

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

2011-01-01

172

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

173

Development of Catechol 2,3-Dioxygenase-Specific Primers for Monitoring Bioremediation by Competitive Quantitative PCR  

PubMed Central

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. Primers that can successfully amplify a 238-bp catechol 2,3-dioxygenase gene fragment from eight different bacteria are described. The identities of the amplicons were confirmed by hybridization with a 238-bp catechol 2,3-dioxygenase probe. The detection limit was 102 to 103 gene copies, which was lowered to 100 to 101 gene copies by hybridization. Using the dioxygenase-specific primers, an increase in catechol 2,3-dioxygenase genes was detected in petroleum-amended soils. The dioxygenase genes were enumerated by competitive quantitative PCR with a 163-bp competitor that was amplified using the same primers. Target and competitor sequences had identical amplification kinetics. Potential PCR inhibitors that could coextract with DNA, nonamplifying DNA, soil factors (humics), and soil pollutants (toluene) did not impact enumeration. Therefore, this technique can be used to accurately and reproducibly quantify catechol 2,3-dioxygenase genes in complex environments such as petroleum-contaminated soil. Direct, non-cultivation-based molecular techniques for detecting and enumerating microbial pollutant-biodegrading genes in environmental samples are powerful tools for monitoring bioremediation and developing field evidence in support of natural attenuation. PMID:10653735

Mesarch, Matthew B.; Nakatsu, Cindy H.; Nies, Loring

2000-01-01

174

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

PubMed

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

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

2014-07-01

175

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. PMID:20652142

2010-01-01

176

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

177

Medicinal Chemistry of Catechol O-Methyltransferase (COMT) Inhibitors and Their Therapeutic Utility.  

PubMed

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

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

2014-11-13

178

Identification of major metabolites of the catechol-O-methyltransferase-inhibitor nitecapone in human urine.  

PubMed

Metabolites of nitecapone [3-(3,4-dihydroxy-5-nitrobenzylidene)-2,4-pentanedione], a potent new catechol-O-methytransferase-inhibitor, were isolated from human urine both after hydrolysis with beta-glucuronidase and as intact conjugates. Seven phase-I metabolites and corresponding glucuronides were identified using electron ionization and fast atom bombardment mass spectrometry, IR spectroscopy, and proton NMR spectrometry. The most abundant metabolite in urine was the glucuronide of unchanged nitecapone, representing 60-65% of the metabolites found. The main phase-I metabolic reaction was reduction of the side chain double bond and carbonyl groups. One of the major metabolites was formed by cleavage of the side chain by retro aldol condensation. All phase-I metabolites were present mainly as their glucuronic acid conjugates. The 3-nitrocatechol-structure of nitecapone seems to hinder nitro-reduction, catechol-O-methylation, and sulfation reactions. PMID:1673395

Taskinen, J; Wikberg, T; Ottoila, P; Kanner, L; Lotta, T; Pippuri, A; Bäckström, R

1991-01-01

179

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

180

Catechol-mediated reversible binding of multivalent cations in eumelanin half-cells.  

PubMed

Electrochemical storage systems that utilize divalent cations such as Mg2+ can improve the volumetric charge storage capacities compared to those that use monovalent ions. Here, a cathode based on naturally derived melanin pigments is used in secondary Mg2+ batteries. Redox active catechol groups in melanins permit efficient and reversible exchange of divalent Mg2+ cations to preserve charge storage capacity in biopolymer cathodes for more than 500 cycles. PMID:25155817

Kim, Young Jo; Wu, Wei; Chun, Sang-Eun; Whitacre, Jay F; Bettinger, Christopher J

2014-10-01

181

Low activity allele of catechol-O-methyltransferase gene associated with rapid cycling bipolar disorder  

Microsoft Academic Search

Catechol-O-methyltransferase (COMT) plays a major role in the breakdown of catecholamines.1 An amino acid polymorphism (val-108-met) determines high and low activity of the enzyme.2,3 A recent study in a small sample of patients with velo-cardio-facial syndrome who had bipolar affective disorder suggested that the Met (low activity) COMT allele might be associated with rapid-cycling in this population.4 We therefore tested

G Kirov; K C Murphy; M J Arranz; I Jones; F McCandles; H Kunugi; R M Murray; P McGuffin; D A Collier; M J Owen; N Craddock

1998-01-01

182

Impact of Catechol-O-Methyltransferase on Prefrontal Brain Functioning in Schizophrenia Spectrum Disorders  

Microsoft Academic Search

The enzyme catechol-O-methyltransferase (COMT) has attracted increasing interest regarding a genetic disposition towards schizophrenias and as a modulator of prefrontal brain function. A common SNP in the COMT gene causes a Val to Met transition at AA158\\/AA108 (Val158Met), resulting in reduced COMT activity in Met allele carriers. An impact of COMT genotype on cognition has been well established; however, the

Ann-Christine Ehlis; Andreas Reif; Martin J Herrmann; Klaus-Peter Lesch; Andreas J Fallgatter; A-C Ehlis

2007-01-01

183

Synthesis of some novel potent and selective catechol O-methyltransferase inhibitors.  

PubMed

A series of disubstituted catechol derivatives was synthesized and tested as potential COMT inhibitors. The most active compounds were more than 1000 times more potent (IC50 = 3-6 nM) in vitro than the known COMT inhibitor, 3',4'-dihydroxy-2-methylpropiophenone (U 0521, IC50 = 6000 nM). The new compounds were also highly selective COMT inhibitors with no activity against other essential enzymes involved in the synthesis and metabolism of catecholamines. PMID:2704029

Bäckström, R; Honkanen, E; Pippuri, A; Kairisalo, P; Pystynen, J; Heinola, K; Nissinen, E; Linden, I B; Männistö, P T; Kaakkola, S

1989-04-01

184

Less is more: reduced catechol production permits Pseudomonas putida F1 to grow on styrene.  

PubMed

Pseudomonas putida F1 is unable to grow on styrene due to the accumulation of 3-vinylcatechol, a toxic metabolite that is produced through the toluene degradation (tod) pathway and causes catechol-2,3-dioxygenase (C23O) inactivation. In this study, we characterized a spontaneous F1 mutant, designated SF1, which acquired the ability to grow on styrene and did not accumulate 3-vinylcatechol. Whereas adaptation to new aromatic substrates has typically been shown to involve increased C23O activity or the acquisition of resistance to C23O inactivation, SF1 retained wild-type C23O activity. Surprisingly, SF1 grew more slowly on toluene, its native substrate, and exhibited reduced toluene dioxygenase (TDO) activity (approximately 50?% of that of F1), the enzyme responsible for ring hydroxylation and subsequent production of 3-vinylcatechol. DNA sequence analysis of the tod operon of SF1 revealed a single base pair mutation in todA (C479T), a gene encoding the reductase component of TDO. Replacement of the wild-type todA allele in F1 with todA(C479T) reduced TDO activity to SF1 levels, obviated vinylcatechol accumulation, and conferred the ability to grow on styrene. This novel 'less is more' strategy - reduced catechol production as a means to expand growth substrate range - sheds light on an alternative approach for managing catechol toxicity during the metabolism of aromatic compounds. PMID:22902727

George, Kevin W; Hay, Anthony

2012-11-01

185

Inhibition of Choline Transport by Redox-active Cholinomimetic Bis-catechol Reagents  

PubMed Central

Both N,N?-(2,3-dihydroxybenzyl)-N,N,N?,N?-tetramethyl-1,6-hexanediamine dibromide (DTH, 6) and N,N?-(2,3-dihydroxybenzyl)-N,N,N?,N?-tetramethyl-1,10-decanediamine dibromide (DTD, 7), which are symmetrical bis-catechol substituted hexamethonium and decamethonium analogues, respectively, were found to inhibit high affinity choline transport in mouse brain synaptosomes. Inhibitory properties were evaluated using an extraordinarily sensitive capillary electrophoresis method employing electrochemical detection at an enzyme-modified microelectrode. Dose-response curves were generated for each inhibitor and IC50 values were determined to be 76 ?M for 6 and 21 ?M for 7. Lineweaver-Burk analysis revealed that both molecules inhibit high affinity choline uptake by a mixed inhibition mechanism. The KI values for 6 and 7 were determined to be 73 ± 1 and 31 ± 2 ?M, respectively. The inhibition properties were further compared to a series of mono-catechol analogues, 3-[(trimethylammonio)methyl]catechol (1), N,N-dimethylepinephrine (4) and 6-hydroxy-N,N-dimethylepinephrine (5), as well as the well-characterized hemicholinium inhibitors, hemicholinium-15 (HC-15, 8) and hemicholinum-3 (HC-3, 9). PMID:17827016

Cai, Shuang; Mukherjee, Jhindan; Viranga Tillekeratne, L. M.; Hudson, Richard A.; Kirchhoff, Jon R.

2007-01-01

186

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

PubMed

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

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

2014-02-01

187

Mapping QTLs influencing rice floral morphology using recombinant inbred lines derived from a cross between Oryza sativa L. and Oryza rufipogon Griff  

Microsoft Academic Search

To understand the genetic basis of floral traits associated with the mating system in rice, we analyzed pistil, stamen and glume traits using a recombinant inbred line population, derived from a cross between an Asian cultivated rice ( Oryza sativa L.), Pei-kuh, and a wild rice ( Oryza rufipogon Griff.), W1944. Quantitative trait loci (QTLs) affecting floral morphology were detected

Y. Uga; Y. Fukuta; H. W. Cai; H. Iwata; R. Ohsawa; H. Morishima; T. Fujimura

2003-01-01

188

D-Amino acid oxidase: new findings  

Microsoft Academic Search

The most recent research on D-amino acid oxidases and D-amino acid metabolism has revealed new, intriguing properties of flavoenzymes and enlighted novel biotechnological uses of this catalyst. Concerning the in vivo function of the enzyme, new findings on the physiological role of D-amino acid oxidase point to a detoxifying function of the enzyme in metabolizing exogenous D-amino acids in animals.

M. S. Pilone; J. H. Dunant

2000-01-01

189

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

190

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

191

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

192

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

193

Assays of D-amino acid oxidases.  

PubMed

D-Amino acid oxidase and D-aspartate oxidase are two well-known FAD-containing flavooxidases that catalyze the same reaction (the oxidative deamination) on different D-amino acids. D-aspartate oxidase is specific for acidic D-amino acids (i.e., D-aspartate and D-glutamate) and D-amino acid oxidase is active on neutral and polar D-amino acids (a low activity is also detected on basic D-amino acids). The assay of these flavoenzymes is of utmost importance in different fields because D-amino acids are common constituents of bacterial cell walls, are present in foods and because free D-serine and D-aspartic acid were identified in brain and peripheral tissues of mammals. In this chapter, we report on the most used methods employed to assay the activity of D-amino acid oxidase and D-aspartate oxidase. Interestingly, their activity can be followed using different assays, namely D-amino acid or oxygen consumption, ?-keto acid or ammonia production, or using artificial dyes as final indicator of the flavin redox reaction. PMID:21956578

Tedeschi, Gabriella; Pollegioni, Loredano; Negri, Armando

2012-01-01

194

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?. PMID:18670615

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

2008-01-01

195

Characterization and genetic analysis of a very high tillering and dwarf rice (Oryza sativa L.) mutant  

E-print Network

. Oryza sativa is cultivated throughout the world but Oryza glaberrima is cultivated mostly in West Africa. Oryza sativa is further classified into three sub-species based on geographical distribution and morphological traits: japonica, indica..., and javanica (Takahashi, 1984). Japonica and indica are mainly grown in temperate and tropical/sub-tropical areas, respectively. Javanica is also known as ?tropical japonica? (Mae, 1997) commonly grown in the U.S. The first trial planting of rice in the U...

Mani, Dhananjay

2009-05-15

196

Heme/copper terminal oxidases  

SciTech Connect

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

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

1996-11-01

197

Targeting NADPH oxidases in vascular pharmacology  

PubMed Central

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

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

2012-01-01

198

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

PubMed

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

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

2014-07-10

199

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

PubMed

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

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

2014-02-28

200

Immobilization of ? galactosidase from Aspergillus oryzae via immunoaffinity support  

Microsoft Academic Search

Polyclonal antibody bound cellulose support has been exploited for the immobilization and stabilization of ? galactosidase from Aspergillus oryzae. Immunoaffinity bound ? galactosidase retained 96.5% of the initial activity on the support. Immobilized ? galactosidase showed broad-spectrum pH optima, pH 4.6–5.5 and temperature at 50–60°C whereas the soluble enzyme exhibited activity peak at pH 4.6 and 50°C. Immunoaffinity bound enzyme

Toshiba Haider; Qayyum Husain

2009-01-01

201

Reduction of aflatoxins by Rhizopus oryzae and Trichoderma reesei.  

PubMed

This study evaluated the ability of the microorganisms Rhizopus oryzae (CCT7560) and Trichoderma reesei (QM9414), producers of generally recognized as safe (GRAS) enzymes, to reduce the level of aflatoxins B1, B2, G1, G2, and M1. The variables considered to the screening were the initial number of spores in the inoculum and the culture time. The culture was conducted in contaminated 4 % potato dextrose agar (PDA) medium, and the residual mycotoxins were determined every 24 h by HPLC-FL. The fungus R. oryzae has reduced aflatoxins B1, B2, and G1 in the 96 h and aflatoxins M1 and G2 in the range of 120 h of culture by approximately 100 %. The fungus T. reesei has reduced aflatoxins B1, B2, and M1 in the 96 h and aflatoxin G1 in the range of 120 h of culture by approximately 100 %. The highest reduction occurred in the middle of R. oryzae culture. PMID:24925827

Hackbart, H C S; Machado, A R; Christ-Ribeiro, A; Prietto, L; Badiale-Furlong, E

2014-08-01

202

Characterization of the sulfurtransferase family from Oryza sativa L.  

PubMed

Sulfurtransferases (Str) comprise a group of enzymes widely distributed in archaea, eubacteria, and eukaryota which catalyze the transfer of a sulfur atom from suitable sulfur donors to nucleophilic sulfur acceptors. Neither the in vivo sulfur donors nor the acceptors of Str could be clearly identified in any of the organisms investigated so far. In Oryza sativa L. 24 Str (OsStr) encoding genes have been identified and subdivided into six groups according to their sequence homology. To half of the Oryza Str a direct homolog and to 40% at least a similar protein in Arabidopsis thaliana (L.) Heynh. could be allocated. Only the group comprising two-domain Str contains more Oryza Str than Arabidopsis Str. According to EST abundance analysis most of the OsStr mRNAs accumulate in several plant tissues. OsStr22, the homolog to the best characterized Str1 from Arabidopsis (AtStr1), shows the highest expression in middle-aged plants whereas AtStr1 shows the highest expression in senescent plants. Heterologously expressed and purified OsStr22 shows very low enzyme activity in comparison to the Arabidopsis and the Brassica napus L. Str. The data obtained so far constitute the basis to analyze differences among the Str family from monocotyledonous and dicotyledonous plants. PMID:21821426

Guretzki, Sebastian; Papenbrock, Jutta

2011-09-01

203

Purification and Partial Biochemical Characterization of Polyphenol Oxidase from Mango (Mangifera indica cv. Manila).  

PubMed

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

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

2014-10-01

204

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

205

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

PubMed

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

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

2014-07-01

206

Decolorization of the textile dyes using purified banana pulp polyphenol oxidase.  

PubMed

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 degrees C and 7.0, respectively for its activity. Catechol was found to be a suitable substrate for banana pulp PPO that showed V(max), 0.041 mM min(-1) and K(m), 1.6 mM. The enzyme activity was inhibited by sodium metabisulfite, citric acid, cysteine, and beta-mercaptoethanol at 10 mM concentration. The purified enzyme could decolorize (90%) Direct Red 5B (160 microg mL(-1)) dye within 48 h and Direct Blue GLL (400 microg mL(-1)) dye up to 85% within 90 h. The GC-MS analysis indicated the presence of 4-hydroxy-benzenesulfonic acid and Naphthalene-1,2,3,6-tetraol in the degradation products of Direct Red 5B, and 5-(4-Diazenyl-naphthalene-1-ylazo)-8-hydroxy-naphthalene-2-sulfonic acid and 2-(4-Diazenyl-naphthalene-1-ylazo)-benzenesulfonic acid in the degradation products of Direct Blue GLL. PMID:21598798

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

2011-04-01

207

Catechol Redox Induced Formation of Metal Core-Polymer Shell Nanoparticles  

PubMed Central

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

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

2011-01-01

208

Design, synthesis, and anti-integrase activity of catechol-DKA hybrids.  

PubMed

Following the discovery of diketoacid-containing compounds as HIV-1 integrase (IN) inhibitors, a plethora of new molecules have been published leading to four drugs under clinical trial. In an attempt to rationally design new dimeric diketoacids (DKAs) targeting two divalent metal ions on the active site of IN, potent inhibitors against purified IN were found with varied selectivity for strand transfer. In this context, we designed and synthesized a new series of catechol-DKA hybrids. These compounds presented micromolar anti-integrase activities with moderate antiviral properties. PMID:16412645

Maurin, Cédric; Bailly, Fabrice; Mbemba, Gladys; Mouscadet, Jean François; Cotelle, Philippe

2006-05-01

209

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

PubMed

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

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

2014-10-01

210

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

PubMed

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

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

2013-06-01

211

Proline dehydrogenase (oxidase) in cancer.  

PubMed

Proline dehydrogenase (oxidase, PRODH/POX), the first enzyme in the proline degradative pathway, plays a special role in tumorigenesis and tumor development. Proline metabolism catalyzed by PRODH/POX is closely linked with the tricarboxylic acid (TCA) cycle and urea cycle. The proline cycle formed by the interconversion of proline and ?(1) -pyrroline-5-carboxylate (P5C) between mitochondria and cytosol interlocks with pentose phosphate pathway. Importantly, by catalyzing proline to P5C, PRODH/POX donates electrons into the electron transport chain to generate ROS or ATP. In earlier studies, we found that PRODH/POX functions as a tumor suppressor to initiate apoptosis, inhibit tumor growth, and block the cell cycle, all by ROS signaling. It also suppresses hypoxia inducible factor signaling by increasing ?-ketoglutarate. During tumor progression, PRODH/POX is under the control of various tumor-associated factors, such as tumor suppressor p53, inflammatory factor peroxisome proliferator-activated receptor gamma (PPAR?), onco-miRNA miR-23b*, and oncogenic transcription factor c-MYC. Recent studies revealed the two-sided features of PRODH/POX-mediated regulation. Under metabolic stress such as oxygen and glucose deprivation, PRODH/POX can be induced to serve as a tumor survival factor through ATP production or ROS-induced autophagy. The paradoxical roles of PRODH/POX can be understood considering the temporal and spatial context of the tumor. Further studies will provide additional insights into this protein and on its metabolic effects in tumors, which may lead to new therapeutic strategies. PMID:22886911

Liu, Wei; Phang, James M

2012-01-01

212

Hyperuricemia and xanthine oxidase in preeclampsia, revisited.  

PubMed

Hyperuricemia is associated with the severity of preeclampsia and with fetal outcome. Traditionally the high uric acid concentration in preeclampsia has been attributed soley 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 formation of reactive oxygen species when the enzyme is in the oxidase form. Several factors can increase the holoenzyme activity and the conversion of xanthine dehydrogenase/oxidase to its oxidase form. These factors include hypoxia-reperfusion, cytokines, and increased substrate availability (xanthine and hypoxanthine). Preeclampsia is characterized by hyperuricemia and signs of increased formation of reactive oxygen species and decreased levels of antioxidants. Preeclampsia is also characterized by shallow implantation, producing a relatively hypoxic maternal-fetal interface, and increased turnover of trophoblast tissue, which can result in higher xanthine and hypoxanthine concentrations and higher levels of circulating cytokines. These mechanisms can lead to increased production of uric acid and free radicals and contribute to the hyperuricemia and increased oxidative stress present in preeclampsia. PMID:8572024

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

1996-01-01

213

The promoting effects of alginate oligosaccharides on root development in Oryza sativa L. mediated by auxin signaling.  

PubMed

Alginate oligosaccharides (AOS), which are marine oligosaccharides, are involved in regulating plant root growth, but the promotion mechanism for AOS remains unclear. Here, AOS (10-80mg/L) induced the expression of auxin-related gene (OsYUCCA1, OsYUCCA5, OsIAA11 and OsPIN1) in rice (Oryza sativa L.) tissues to accelerate auxin biosynthesis and transport, and reduced indole-3-acetic acid (IAA) oxidase activity in rice roots. These changes resulted in the increase of 37.8% in IAA concentration in rice roots, thereby inducing the expression of root development-related genes, promoting root growth in a dose-dependent manner, which were inhibited by auxin transport inhibitor 2,3,5-triiodo benzoic acid (TIBA) and calcium-chelating agent ethylene glycol bis (2-aminoethyl) tetraacetic acid (EGTA). AOS also induced calcium signaling generation in rice roots. Those results indicated that auxin mediated AOS regulation of root development, and calcium signaling may act mainly in the upstream of auxin in the regulation of AOS on rice root development. PMID:25256506

Zhang, Yunhong; Yin, Heng; Zhao, Xiaoming; Wang, Wenxia; Du, Yuguang; He, Ailing; Sun, Kegang

2014-11-26

214

Experimental and Computational Evidence for the Mechanism of Intradiol Catechol Dioxygenation by Non-Heme Iron(III) Complexes.  

PubMed

Catechol intradiol dioxygenation is a unique reaction catalyzed by iron-dependent enzymes and non-heme iron(III) complexes. The mechanism by which these systems activate dioxygen in this important metabolic process remains controversial. Using a combination of kinetic measurements and computational modelling of multiple iron(III) catecholato complexes, we have elucidated the catechol cleavage mechanism and show that oxygen binds the iron center by partial dissociation of the substrate from the iron complex. The iron(III) superoxide complex that is formed subsequently attacks the carbon atom of the substrate by a rate-determining C?O bond formation step. PMID:25322920

Jastrzebski, Robin; Quesne, Matthew G; Weckhuysen, Bert M; de Visser, Sam P; Bruijnincx, Pieter C A

2014-11-24

215

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

PubMed

In this paper, we provide the first report of utilizing recombinant fungal whole cells in enzymatic biodiesel production. 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 for lipase-catalyzed methanolysis. The addition of 5% water to the reaction mixture was effective in both preventing the lipase inactivation by methanol and facilitating the acyl migration in partial glycerides, resulting in the final methyl ester content of 94% even in the tenth batch cycle. A comparative study showed that FHL-producing A. oryzae attained a higher final methyl ester content and higher lipase stability than Rhizopus oryzae, the previously developed whole-cell biocatalyst. Although both FHL and R. oryzae lipase exhibit 1,3-regiospecificity towards triglyceride, R. oryzae accumulated a much higher amount of sn-2 isomers of partial glycerides, whereas FHL-producing A. oryzae maintained a low level of the sn-2 isomers. This is probably because FHL efficiently facilitates the acyl migration from the sn-2 to the sn-1(3) position in partial glycerides. These findings indicate that the newly developed FHL-producing A. oryzae is an effective whole-cell biocatalyst for enzymatic biodiesel production. PMID:18795281

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

2008-12-01

216

Population structure of Eleusine isolates of Pyricularia oryzae and its evolutionary implications  

Microsoft Academic Search

Population structure of Eleusine isolates of Pyricularia oryzae (Magnaporthe oryzae) was examined using DNA markers. On the basis of rDNA sequences, Eleusine isolates were divided into two groups. One group clustered with Triticum isolates, while the other clustered with Eragrostis isolates. This grouping was supported by DNA fingerprinting with three repetitive elements: MGR586, MGR583, and grasshopper. These results suggest that

Masaki Tanaka; Hitoshi Nakayashiki; Yukio Tosa

2009-01-01

217

Phylogeography of Asian wild rice, Oryza rufipogon: a genome-wide view  

E-print Network

Phylogeography of Asian wild rice, Oryza rufipogon: a genome-wide view PU HUANG,* JEANMAIRE MOLINA Technologies, University of Georgia, Athens, GA 30621, USA Abstract Asian wild rice (Oryza rufipogon of cultivated Asian rice (O. sativa). Studies of the geographic structure of O. rufipogon, based on chloroplast

Purugganan, Michael D.

218

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

PubMed Central

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

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

2014-01-01

219

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

Microsoft Academic Search

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

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

1992-01-01

220

Fumigant toxicity of essential oils and pure compounds against Sitophilus oryzae L. (Coleoptera: Curculionidae)  

Microsoft Academic Search

In this study, Zingiber officinale (Zingiberaceae) and Piper cubeba (Piperaceae) essential oils and two pure natural terpenes, ?-pinene and ?-caryophyllene, were evaluated for their repellent, insecticidal and acetylcholinesterase enzyme inhibitory activities against rice weevil, Sitophilus oryzae. In the repellency assay, Zingiber officinale and Piper cubeba essential oils repelled S. oryzae adults significantly at 0.003125% while ?-pinene and ?-caryophyllene repelled S.

M. K. Chaubey

2012-01-01

221

Improved annotation through genome-scale metabolic modeling of Aspergillus oryzae  

Microsoft Academic Search

BACKGROUND: Since ancient times the filamentous fungus Aspergillus oryzae has been used in the fermentation industry for the production of fermented sauces and the production of industrial enzymes. Recently, the genome sequence of A. oryzae with 12,074 annotated genes was released but the number of hypothetical proteins accounted for more than 50% of the annotated genes. Considering the industrial importance

Wanwipa Vongsangnak; Peter Olsen; Kim Hansen; Steen Krogsgaard; Jens Nielsen

2008-01-01

222

Interindividual variability of phenol- and catechol-sulphotransferases in platelets from adults and newborns.  

PubMed Central

1 Phenol- and catechol- sulphotransferase activities were measured with p-nitrophenol and dopamine as substrates in platelets obtained from 100 newborns and 100 healthy adults. 2 Mean +/- (s.d.) estimates of catechol sulphotransferase activity were 7.07 +/- 5.93 (adult) and 13.3 +/- 6.42 (newborn) pmol min(-1) mg(-1) protein, respectively (P < 0.001). The coefficients of variation were 84% (adult) and 48% (newborn). The frequency distribution of sulphotransferase activity was symmetric and did not deviate significantly from normality in newborn platelets, but was positively skewed in adult platelets. 3 Mean +/- (s.d.) estimates of phenol sulphotransferase activity were 3.01 +/- 3.21 (adult) and 4.80 +/- 4.34 (newborn) pmol min(-1) mg(-1), respectively (P < 0.001). The coefficients of variation were 107% (adult) and 90% (newborn). The frequency distribution of sulphotransferase activity was positively skewed in both newborn and adult platelets. 4 Since sulphotransferase activity in platelets is well-expressed at birth and a prenatal development of sulphotransferase has been described in mid-gestational human foetal liver, the newborn should be able to sulphate drugs. PMID:12959278

Pacifici, G M; Marchi, G

1993-01-01

223

Degradation of Phenolic Compounds and Ring Cleavage of Catechol by Phanerochaete chrysosporium  

PubMed Central

POL-88, a mutant of the white-rot fungus Phanerochaete chrysosporium, was selected for diminished phenol-oxidizing enzyme activity. A wide variety of phenolic compounds were degraded by ligninolytic cultures of this mutant. With several o-diphenolic substrates, degradation intermediates were produced that had UV spectra consistent with muconic acids. Extensive spectrophotometric and polarographic assays failed to detect classical ring-cleaving dioxygenases in cell homogenates or in extracts from ligninolytic cultures. Even so, a sensitive carrier-trapping assay showed that intact cultures degraded [U-14C]catechol to [14C]muconic acid, establishing the presence of a system capable of 1,2-intradiol fission. Significant accumulation of [14C]muconic acid into carrier occurred only when evolution of 14CO2 from [14C]catechol was inhibited by treating cultures with excess nutrient nitrogen (e.g., l-glutamic acid) or with cycloheximide. l-Glutamic acid is known from past work to repress the ligninolytic system in P. chrysosporium and to mimic the effect of cycloheximide. The results here indicate, therefore, that the enzyme system responsible for degrading ring-cleavage products to CO2 turns over faster than does the system responsible for ring cleavage. PMID:16346340

Leatham, Gary F.; Crawford, R. L.; Kirk, T. Kent

1983-01-01

224

Degradation of phenolic compounds and ring cleavage of catechol by Phanerochaete chrysosporium  

SciTech Connect

POL-88, a mutant of the white-rot fungus Phanerochaete chrysosporium was selected for diminished phenol-oxidizing enzyme activity. A wide variety of phenolic compounds were degraded by ligninolytic cultures of this mutant. With several o-diphenolic substrates, degradation intermediates were produced that had UV spectra consistent with muconic acids. Extensive spectrophotometric and polarographic assays failed to detect classical ring-cleaving dioxygenases in cell homogenates or in extracts from ligninolytic cultures. Even so, a sensitive carrier-trapping assay showed that intact cultures degraded (U-/sup 14/C)catechol to (/sup 14/C)muconic acid, establishing the presence of a system capable of 1,2-intradiol fission. Significant accumulation of (/sup 14/C) muconic acid into carrier occurred only when evolution of /sup 14/CO/sub 2/ from (/sup 14/C)catechol was inhibited by treating cultures with excess nutrient nitrogen (e.g., L-glutamic acid) or with cycloheximide. L-Glutamic acid is known from past work to repress the ligninolytic system in P. chrysosporium and to mimic the effect of cycloheximide. The results here indicate, therefore, that the enzyme system responsible for degrading ring-cleavage products to CO/sub 2/ turns over faster than does the system responsible for ring cleavage.

Leathum, G.F.; Crawford, R.L.; Kirk, T.K.

1983-07-01

225

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

SciTech Connect

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

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

1984-03-01

226

Sulfite oxidase activity in Thiobacillus novellus.  

PubMed

Thiobacillus novellus shows a maximum induction of sulfite oxidase activity and a maximum growth rate as a result of supplementing the autotrophic growth medium with 4.0 microM ammonium molybdate. Cells grown in the presence of molybdate showed approximately 10-fold increases in the amount of enzyme-associated molybdenum and in the sulfite-to-cytochrome c and sulfite-to-ferricyanide reductase activities. The effect of exogenous molybdate was not discernible with cells grown in the absence of thiosulfate. Tungsten inhibited the growth of T. novellus and the expression of sulfite oxidase activity. PMID:6630156

Southerland, W M; Toghrol, F

1983-11-01

227

Lysyl oxidases in the trabecular meshwork.  

PubMed

The mechanical properties of the extracellular matrix (ECM) play an important role in maintaining cellular function and overall tissue homeostasis. Emerging evidence suggests that biomechanical modifications of the ECM may be initiators and/or drivers of disease, exemplified by increased tissue stiffness. Specific ECM cross-linking enzymes (tissue transglutaminase, lysyl oxidase, and lysyl oxidase-like 1) are expressed in the trabecular meshwork and are regulated by transforming growth factor beta (TGF-?) isoforms. As TGF-? isoforms are elevated in the aqueous humor of glaucoma patients, trabecular meshwork stiffness mediated by ECM cross-linking may be responsible for increased aqueous humor outflow resistance and elevated intraocular pressure. PMID:25275908

Wordinger, Robert J; Clark, Abbot F

2014-01-01

228

The rice endophyte Harpophora oryzae genome reveals evolution from a pathogen to a mutualistic endophyte.  

PubMed

The fungus Harpophora oryzae is a close relative of the pathogen Magnaporthe oryzae and a beneficial endosymbiont of wild rice. Here, we show that H. oryzae evolved from a pathogenic ancestor. The overall genomic structures of H. and M. oryzae were found to be similar. However, during interactions with rice, the expression of 11.7% of all genes showed opposing trends in the two fungi, suggesting differences in gene regulation. Moreover, infection patterns, triggering of host defense responses, signal transduction and nutritional preferences exhibited remarkable differentiation between the two fungi. In addition, the H. oryzae genome was found to contain thousands of loci of transposon-like elements, which led to the disruption of 929 genes. Our results indicate that the gain or loss of orphan genes, DNA duplications, gene family expansions and the frequent translocation of transposon-like elements have been important factors in the evolution of this endosymbiont from a pathogenic ancestor. PMID:25048173

Xu, Xi-Hui; Su, Zhen-Zhu; Wang, Chen; Kubicek, Christian P; Feng, Xiao-Xiao; Mao, Li-Juan; Wang, Jia-Ying; Chen, Chen; Lin, Fu-Cheng; Zhang, Chu-Long

2014-01-01

229

Expression der mRNA von Lysyl Oxidase und Lysyl Oxidase Like 2 in Plattenepithelkarzinomen des oberen Aerodigestivtraktes.  

E-print Network

??Die Menge an Lysyl Oxidase (LOX)- und Lysyl Oxidase Like 2 (LOXL2)-mRNA in Zelllinien und Gewebebiopsien aus Plattenepithelkarzinomen des oberen Aerodigestivtraktes (HNSCC) wurde mittels Reverse… (more)

Wege-Rost, Tobias

2009-01-01

230

Relationship between Disease Resistance and Rice Oxalate Oxidases in Transgenic Rice  

PubMed Central

Differential expression of rice oxalate oxidase genes (OsOxO1-4) in rice leaves (Oryza sativa L.) in response to biotic stress was assayed using RT-PCR. OsOxO4 was induced transiently at 12 h in plants inoculated with the pathogens of bacterial blight and that of the wounding control. Inoculation with the rice blast pathogen induced OsOxO2 expression compared to the mock spray control. Overexpressing OsOxO1 or OsOxO4 in rice resulted in elevated transcript levels of the respective transgene as well as OsOxO3 in leaves compared to that in untransformed wild type (WT). In a line of RNA-i transgenic rice plants (i-12), expression of all four OsOxO genes except that of OsOxO2 was severely inhibited. Oxalate oxidase (OxO, EC 1.2.3.4) activity in plants overexpressing OsOxO1 or OsOxO4 was substantially higher than that in WT and the RNA-i lines. It was found that transgenic rice plants with substantially higher OxO activity were not more resistant to rice blast and bacterial blight than WT. In contrast, some RNA-i lines with less OxO activity seemed to be more resistant to rice blast while some overexpressing lines were more susceptible to rice blast than WT. Therefore, OxO might not be a disease resistance factor in rice. PMID:24205207

Zhang, Xian Yong; Nie, Zhuan Hua; Wang, Wen Juan; Leung, David W. M.; Xu, Da Gao; Chen, Bai Ling; Chen, Zhe; Zeng, Lie Xian; Liu, E. E.

2013-01-01

231

Kinetics and specificity of guinea pig liver aldehyde oxidase and bovine milk xanthine oxidase towards substituted benzaldehydes  

Microsoft Academic Search

Molybdenum-containing enzymes, aldehyde oxidase and xanthine oxidase, are im- portant in the oxidation of N-heterocyclic xenobiotics. However, the role of these en- zymes in the oxidation of drug-derived aldehydes has not been established. The present investigation describes the interaction of eleven structurally related benzaldehydes with guinea pig liver aldehyde oxidase and bovine milk xanthine oxidase, since they have similar substrate

Georgios I. Panoutsopoulos; Christine Beedham

2004-01-01

232

Effect of monoamine oxidase A and B and of catechol-O-methyltransferase inhibition on L-DOPA-induced circling behavior  

Microsoft Academic Search

Summary The effect of enzyme-inhibiting adjuvants on L-DOPA + benserazide-induced contralateral turning in unilateral 6-hydroxydopamine (6-OHDA)-lesioned rats was studied. Both the number of turns and the duration of turning were examined. Inhibition of MAO-A with 10mg\\/kg Ro 41–1049 increased both parameters; inhibition of COMT with 10mg\\/kg Ro 40–7592 had a similar effect. In contrast, inhibition of MAO-B with 10mg\\/kg Ro

M. J. Heeringa; F. d'Agostini; P. DeBoer; M. DaPrada; G. Damsma

1997-01-01

233

Therapy with central active catechol-O-methyltransferase (COMT)-inhibitors: is addition of monoamine oxidase (MAO)-inhibitors necessary to slow progress of neurodegenerative disorders?  

Microsoft Academic Search

Summary Neurotrophic factors, like e.g. nerve growth factor (NGF), neurotrophin 3 (NT-3) or brain-derived neurotrophic factor (BDNF) promote the survival and function of neurones in the peripheral and central nervous system. Dopamine or other biogenic amines induce the biosynthesis of neurotrophic factors in glial and neuronal cells. Therefore inhibition of enzymes, like the extraneuronal and neuronal located MAO or the

Th. Müller; W. Kuhn; H. Przuntek

1993-01-01

234

Combined analysis of association between personality traits and three functional polymorphisms in the tyrosine hydroxylase, monoamine oxidase A, and catechol- O-methyltransferase genes  

Microsoft Academic Search

Several molecular genetic studies have been conducted with regard to the association between catecholamine-related genes and personality traits. However, the results of replication studies did not always coincide. One of the possible reasons may be that the effect exerted by the individual gene is small. In the present study, we investigated the association between personality traits and systematic combination of

Mamoru Tochigi; Takeshi Otowa; Hiroyuki Hibino; Chieko Kato; Toshiyuki Otani; Tadashi Umekage; Takeshi Utsumi; Nobumasa Kato; Tsukasa Sasaki

2006-01-01

235

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

236

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

Microsoft Academic Search

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

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

2002-01-01

237

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

238

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

PubMed Central

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

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

2012-01-01

239

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

PubMed

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

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

2014-01-01

240

Influence of the physicochemical properties of clay minerals on the degree of darkening via polycondensation reactions between catechol and glycine  

Microsoft Academic Search

Polycondensation reactions between amino acids and phenols are an important pathway for humification, and clay minerals are able to catalyze these reactions. In the present study, we investigated the influence of the physicochemical properties of some clay minerals on polycondensation reactions between catechol (CT) and glycine (Gly). The polycondensation of CT and Gly was evaluated using the specific absorbance at

Akitaka Miura; Ryo Okabe; Kenji Izumo; Masami Fukushima

2009-01-01

241

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...

242

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...

243

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...

244

Catechol-functionalized adhesive polymer nanoparticles for controlled local release of bone morphogenetic protein-2 from titanium surface.  

PubMed

We report on a novel surface functionalization approach to equip the titanium (Ti) surfaces with osteogenic properties. A key feature of the approach is the treatment of the Ti surfaces with Ti-adhesive nanoparticles that can stably load and controllably release bone morphogenetic protein-2 (BMP-2). Ti-adhesive nanoparticles were prepared by self-assembly of a catechol-functionalized poly(amino acid) diblock copolymer, catechol-poly(L-aspartic acid)-b-poly(L-phenylalanine) (Cat-PAsp-PPhe). The nanoparticles consist of Ti-adhesive peripheral catechol groups, anionic PAsp shells, and PPhe inner cores. Field-emission scanning electron microscopy (Fe-SEM) images showed that the Ti-adhesive nanoparticles could be uniformly immobilized on Ti surfaces. X-ray photoelectron spectroscopy (XPS) confirmed the successful anchoring of nanoparticles onto Ti surfaces. After surface immobilization of the nanoparticles, the static water contact angle of the Ti substrate decreased from 75.3° to 50.0° or 36.4°, depending on the surface nanoparticle. Fluorescence microscopic analysis showed that BMP-2 could be effectively incorporated onto the Ti surface with adhesive nanoparticles. BMP-2 was controllably released for up to 40 days. The Ti substrate functionalized with BMP-2-incorporated nanoparticles significantly promoted attachment, proliferation, spreading, and alkaline phosphatase (ALP) activity of human adipose-derived stem cell (hADSC). The catechol-functionalized adhesive nanoparticles may be applied to various medical devices to create surfaces for improved performance. PMID:23727196

Lee, Hong Jae; Koo, Ahn Na; Lee, Suk Won; Lee, Myung Hyun; Lee, Sang Cheon

2013-09-10

245

The Catechol-O-Methyl Transferase Val158Met Polymorphism and Experience of Reward in the Flow of Daily Life  

Microsoft Academic Search

Genetic moderation of experience of reward in response to environmental stimuli is relevant for the study of many psychiatric disorders. Experience of reward, however, is difficult to capture, as it involves small fluctuations in affect in response to small events in the flow of daily life. This study examined a momentary assessment reward phenotype in relation to the catechol-O-methyl transferase

Marieke Wichers; Mari Aguilera; Gunter Kenis; Lydia Krabbendam; Inez Myin-Germeys; Nele Jacobs; Frenk Peeters; Catherine Derom; Robert Vlietinck; Ron Mengelers; Philippe Delespaul; Jim van Os

2008-01-01

246

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

E-print Network

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

McCusker, James K.

247

Mesoporous carbon nitride based biosensor for highly sensitive and selective analysis of phenol and catechol in compost bioremediation.  

PubMed

Herein, we reported here a promising biosensor by taking advantage of the unique ordered mesoporous carbon nitride material (MCN) to convert the recognition information into a detectable signal with enzyme firstly, which could realize the sensitive, especially, selective detection of catechol and phenol in compost bioremediation samples. The mechanism including the MCN based on electrochemical, biosensor assembly, enzyme immobilization, and enzyme kinetics (elucidating the lower detection limit, different linear range and sensitivity) was discussed in detail. Under optimal conditions, GCE/MCN/Tyr biosensor was evaluated by chronoamperometry measurements and the reduction current of phenol and catechol was proportional to their concentration in the range of 5.00 × 10(-8)-9.50 × 10(-6)M and 5.00 × 10(-8)-1.25 × 10(-5)M with a correlation coefficient of 0.9991 and 0.9881, respectively. The detection limits of catechol and phenol were 10.24 nM and 15.00 nM (S/N=3), respectively. Besides, the data obtained from interference experiments indicated that the biosensor had good specificity. All the results showed that this material is suitable for load enzyme and applied to the biosensor due to the proposed biosensor exhibited improved analytical performances in terms of the detection limit and specificity, provided a powerful tool for rapid, sensitive, especially, selective monitoring of catechol and phenol simultaneously. Moreover, the obtained results may open the way to other MCN-enzyme applications in the environmental field. PMID:24951922

Zhou, Yaoyu; Tang, Lin; Zeng, Guangming; Chen, Jun; Cai, Ye; Zhang, Yi; Yang, Guide; Liu, Yuanyuan; Zhang, Chen; Tang, Wangwang

2014-11-15

248

Development of a biofuel cell using glucose-oxidase- and bilirubin-oxidase-based electrodes  

Microsoft Academic Search

Biofuel cells have a tremendous opportunity to provide much higher energy densities and smaller footprints than batteries\\u000a for powering implantable medical devices, leading to less intrusive implantable devices with longer lifetimes. This paper\\u000a introduces biofuel cell anode and cathode designs based on mediated glucose oxidation by glucose oxidase and oxygen reduction\\u000a by bilirubin oxidase, respectively. We report here the progress

Jinseong Kim; Jeffrey Parkey; Christopher Rhodes; Anuncia Gonzalez-Martin

2009-01-01

249

Cytochrome Oxidase and Its Derivatives. II. The Action of Strong Alkali on Cytochrome Oxidase  

Microsoft Academic Search

By the action of strong alkali (0\\\\cdot 1 to 0\\\\cdot 3 N) cytochrome oxidase is converted to a Schiff's base (aldimine) with practically the same absorption spectrum as that of the Schiff's bases formed at high pH from other haemoproteins a (Lemberg & Newton 1962). Cytochrome oxidase, however, differs from the other haemoproteins a in that a higher pH (more

R. Lemberg

1964-01-01

250

Molecular characterization of wheat polyphenol oxidase (PPO)  

Microsoft Academic Search

It is well-established that the enzyme polyphenol oxidase (PPO) is involved in undesirable browning of noodles, chapattis, middle east flat breads and steamed breads. Methods for measuring PPO activity have been developed, and the variation of PPO activity among wheat (Triticum aestivum L.) cultivars has been well documented. However, there is no report on the identification and characterization of a

T. Demeke; C. Morris

2002-01-01

251

Link Between Monoamine Oxidase and Nitric Oxide  

Microsoft Academic Search

For the last few decades, there has been extensive research and supporting evidence for the role of monoamine oxidase (MAO) activity and its’ possible manipulation in the pathopysiology of neurodegenerative disorders. Although, the role of dopaminergic, noradrenergic and serotonergic systems in central nervous system (CNS) and neurodegenerative diseases have been mostly demonstrated, the intrinsic mechanisms in these systems with relation

Ferhan Girgin Sagin; Eser Y Sozmen; Biltan Ersoz; Gulriz Mentes

2004-01-01

252

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

PubMed Central

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

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

2013-01-01

253

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

254

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

SciTech Connect

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

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

2008-08-01

255

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

PubMed

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 microM 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(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 microM) 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 microM) 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. PMID:18190940

Lo, Yi-Ching; Liu, Yuxin; Lin, Yi-Chin; Shih, Yu-Tzu; Liu, Chi-Ming; Burka, Leo T

2008-04-15

256

A novel class of gibberellin 2-oxidases control semidwarfism, tillering, and root development in rice.  

PubMed

Gibberellin 2-oxidases (GA2oxs) regulate plant growth by inactivating endogenous bioactive gibberellins (GAs). Two classes of GA2oxs inactivate GAs through 2beta-hydroxylation: a larger class of C(19) GA2oxs and a smaller class of C(20) GA2oxs. In this study, we show that members of the rice (Oryza sativa) GA2ox family are differentially regulated and act in concert or individually to control GA levels during flowering, tillering, and seed germination. Using mutant and transgenic analysis, C(20) GA2oxs were shown to play pleiotropic roles regulating rice growth and architecture. In particular, rice overexpressing these GA2oxs exhibited early and increased tillering and adventitious root growth. GA negatively regulated expression of two transcription factors, O. sativa homeobox 1 and TEOSINTE BRANCHED1, which control meristem initiation and axillary bud outgrowth, respectively, and that in turn inhibited tillering. One of three conserved motifs unique to the C(20) GA2oxs (motif III) was found to be important for activity of these GA2oxs. Moreover, C(20) GA2oxs were found to cause less severe GA-defective phenotypes than C(19) GA2oxs. Our studies demonstrate that improvements in plant architecture, such as semidwarfism, increased root systems and higher tiller numbers, could be induced by overexpression of wild-type or modified C(20) GA2oxs. PMID:18952778

Lo, Shuen-Fang; Yang, Show-Ya; Chen, Ku-Ting; Hsing, Yue-Ie; Zeevaart, Jan A D; Chen, Liang-Jwu; Yu, Su-May

2008-10-01

257

A Role for NADPH Oxidase in Antigen Presentation  

PubMed Central

The nicotinamide adenine dinucleotide phosphate (NADPH) oxidase expressed in phagocytes is a multi-subunit enzyme complex that generates superoxide (O2.?). This radical is an important precursor of hydrogen peroxide (H2O2) and other reactive oxygen species needed for microbicidal activity during innate immune responses. Inherited defects in NADPH oxidase give rise to chronic granulomatous disease (CGD), a primary immunodeficiency characterized by recurrent infections and granulomatous inflammation. Interestingly, CGD, CGD carrier status, and oxidase gene polymorphisms have all been associated with autoinflammatory and autoimmune disorders, suggesting a potential role for NADPH oxidase in regulating adaptive immune responses. Here, NADPH oxidase function in antigen processing and presentation is reviewed. NADPH oxidase influences dendritic cell (DC) crosspresentation by major histocompatibility complex class I molecules through regulation of the phagosomal microenvironment, while in B lymphocytes, NADPH oxidase alters epitope selection by major histocompatibility complex class II molecules. PMID:24069023

Gardiner, Gail J.; Deffit, Sarah N.; McLetchie, Shawna; Perez, Liliana; Walline, Crystal C.; Blum, Janice S.

2013-01-01

258

Some studies of alpha-amylase production using Aspergillus oryzae.  

PubMed

The extracellular alpha-amylase production by Aspergillus oryzae was studied in submerged fermentation using an Adlof-Kuhner orbital shaker. The effect of initial pH values in the range of 4 to 7.5 on enzyme production was investigated and initial pH medium of 6.2 +/- 0.1 resulted in enhanced alpha-amylase production. The effect of carbon and nitrogen source and composition was examined and it has been observed that corn starch concentration of 15 g L(-1) has sound effect on enzyme production. The medium containing corn starch, sodium nitrate resulted in considerable higher enzyme production. Further, the yeast extract of 2.5 g L(-1) in the medium produced higher enzyme in view to other organic nitrogen sources. The effect of temperature on alpha-amylase production from 20 to 40 degrees C has been studied and at 35 +/- 1 degrees C higher alpha-amylase has been obtained. The effect of shaker's speed on alpha-amylase production from 50 to 200 rpm was investigated. And at about 180 rpm higher enzyme production has been observed. In the present study, it has been found that glucose has repressing effect on a-amylase production using A. oryzae PTCC5164. PMID:19260332

Esfahanibolandbalaie, Z; Rostami, K; Mirdamadi, S S

2008-11-15

259

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

PubMed

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

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

2014-11-01

260

Weissella oryzae sp. nov., isolated from fermented rice grains.  

PubMed

A taxonomic study was conducted on two Gram-reaction-positive, catalase-negative, irregular short-rod-shaped or coccoid lactic acid bacteria, designated strains SG25(T) and SG23, that were isolated from grains of fermented Japanese rice (Oryza sativa L. subsp. japonica). A phylogenetic analysis based on 16S rRNA gene sequence data clearly showed that the strains belonged to the genus Weissella and were most closely related to Weissella soli LMG 20113(T) (with a sequence similarity of 96.9?% for each novel strain). The peptidoglycan of each strain contained the amino acids glutamic acid, lysine, serine and alanine in a molar ratio of 1.0?:?1.2?:?0.5?:?3.0, respectively. On the basis of the unusual phenotypic characteristics of the novel strains and the low levels of DNA-DNA relatedness recorded between each novel strain and Weissella soli JCM 12536(T), strains SG25(T) and SG23 represent a single novel species in the genus Weissella, for which the name Weissella oryzae sp. nov. is proposed. The type strain is SG25(T) (?=?JCM 18191(T) ?=?DSM 25784(T)). PMID:22843715

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

2013-04-01

261

Co-metabolism of methyl- and chloro-substituted catechols by an Achromobacter sp. possessing a new meta-cleaving oxygenase  

PubMed Central

Co-metabolism of 3-methylcatechol, 4-chlorocatechol and 3,5-dichlorocatechol by an Achromobacter sp. was shown to result in the accumulation of 2-hydroxy-3-methylmuconic semialdehyde, 4-chloro-2-hydroxymuconic semialdehyde and 3,5-dichloro-2-hydroxymuconic semialdehyde respectively. Formation of these products indicated that cleavage of the aromatic nucleus of the substituted catechols was accomplished by a new meta-cleaving enzyme, catechol 1,6-oxygenase. This enzyme was equally active on both chloro- and methyl-substituted catechols. PMID:5492853

Horvath, R. S.

1970-01-01

262

Ferric iron uptake in Erwinia chrysanthemi mediated by chrysobactin and related catechol-type compounds.  

PubMed Central

Erwinia chrysanthemi 3937 possesses a saturable, high-affinity transport system for the ferric complex of its native siderophore chrysobactin, [N-alpha-(2,3-dihydroxybenzoyl)-D-lysyl-L-serine]. Uptake of 55Fe-labeled chrysobactin was completely inhibited by respiratory poison or low temperature and was significantly reduced in rich medium. The kinetics of chrysobactin-mediated iron transport were determined to have apparent Km and Vmax values of about 30 nM and of 90 pmol/mg.min, respectively. Isomers of chrysobactin and analogs with progressively shorter side chains mediated ferric iron transport as efficiently as the native siderophore, which indicates that the chrysobactin receptor primarily recognizes the catechol-iron center. Free ligand in excess only moderately reduced the accumulation of 55Fe. Chrysobactin may therefore be regarded as a true siderophore for E. chrysanthemi. PMID:1624465

Persmark, M; Expert, D; Neilands, J B

1992-01-01

263

Histone acetyltransferase p300 promotes MKL1-mediated transactivation of catechol-O-methyltransferase gene.  

PubMed

Previous studies have revealed that histone acetyltransferase p300 is recruited to the promoters of certain cardiac and smooth muscle specific genes to enhance the transactivation activity of myocardin, which is a master regulator in cardiovascular differentiation and development. Here, we found that the gene encoding catechol-O-methyltransferase (COMT), an important metabolic enzyme catalyzing the conversion of estrogen, is also a target gene of myocardin-related transcription factors (MRTFs). Megakaryoblastic leukemia 1 (MKL1, also named MRTF-A) and p300 could synergistically augment the expression of COMT gene, increase the metabolic rate of estrogen, and thus reduce the proliferation of MCF-7 breast cancer cells stimulated by estrogen. PMID:24096006

Liu, Zhipeng; Luo, Xuegang; Liu, Lei; Zhao, Wenwen; Guo, Shu; Guo, Yu; Wang, Nan; He, Hongpeng; Liao, Xinghua; Ma, Wenjian; Zhou, Hao; Zhang, Tongcun

2013-12-01

264

Adolescent Cannabis Use, Psychosis and Catechol-O-Methyltransferase Genotype in African Americans and Caucasians  

PubMed Central

Cannabis has been reported as a likely risk factor for the development of psychosis, and a gene × environment interaction with the catechol-O-methyltransferase (COMT) gene has been proposed. Moreover, COMT has been separately linked to affective symptoms in psychosis. Despite a high rate of cannabis abuse and affective symptoms in African Americans, no studies exploring a relationship between COMT and psychosis in this group have been reported. An existing database of psychotic patients with and without adolescent cannabis use/affective symptoms was examined, and chi-square analyses for independence were applied separately for both Caucasians and African-Americans to examine genotype associations with adolescent cannabis use and affective symptoms (past or present). The two subject groups did not differ with respect to the prevalence of adolescent cannabis abuse or presence of affective symptoms. Further study is needed, with non-psychotic controls and larger samples. PMID:19633959

Kantrowitz, Joshua T.; Nolan, Karen A.; Sen, Srijan; Simen, Arthur A.; Lachman, Herbert M.; Bowers, Malcolm B.

2009-01-01

265

Adolescent cannabis use, psychosis and catechol-O-methyltransferase genotype in African Americans and Caucasians.  

PubMed

Cannabis has been reported as a likely risk factor for the development of psychosis, and a gene × environment interaction with the catechol-O-methyltransferase (COMT) gene has been proposed. Moreover, COMT has been separately linked to affective symptoms in psychosis. Despite a high rate of cannabis abuse and affective symptoms in African Americans, no studies exploring a relationship between COMT and psychosis in this group have been reported. An existing database of psychotic patients with and without adolescent cannabis use/affective symptoms was examined, and chi-square analyses for independence were applied separately for both Caucasians and African-Americans to examine genotype associations with adolescent cannabis use and affective symptoms (past or present). The two subject groups did not differ with respect to the prevalence of adolescent cannabis abuse or presence of affective symptoms. Further study is needed, with non-psychotic controls and larger samples. PMID:19633959

Kantrowitz, Joshua T; Nolan, Karen A; Sen, Srijan; Simen, Arthur A; Lachman, Herbert M; Bowers, Malcolm B

2009-12-01

266

Theoretical study of the o-OH participation in catechol ester ammonolysis.  

PubMed

The possible catalytic effect of the vicinal hydroxyl group during the ammonolysis of acetylcatechol has been studied by first principle calculations. A very efficient intramolecular catalysis was found to occur when the catechol ester o-OH group is deprotonated: the activation energy of the ammonolysis decreases by 24 kcal mol(-1) as compared to that of acetylphenol ammonolysis. Using this value, the o-oxyanion-catalysed intramolecular ammonolysis was estimated to be orders of magnitude faster than the ammonolysis of acetylphenol or nonionised acetylcatechol. The analogy with the aminolysis of peptidyl-tRNA that occurs during protein biosynthesis implies several orders of magnitude acceleration due to complete or partial deprotonation of its 3'-terminal adenosine 2'-OH providing a mechanistic possibility for general acid-base catalysis by the ribosome. PMID:15731858

Rangelov, Miroslav A; Vayssilov, Georgi N; Yomtova, Vihra M; Petkov, Dimiter D

2005-03-01

267

Iron(III) complexes with meridional ligands as functional models of intradiol-cleaving catechol dioxygenases.  

PubMed

Six dichloroiron(III) complexes of 1,3-bis(2'-arylimino)isoindoline (BAIH) with various N-donor aryl groups have been characterized by spectroscopy (infrared, UV-vis), electrochemistry (cyclic voltammetry), microanalysis, and in two cases X-ray crystallography. The structurally characterized Fe(III)Cl(2)(L(n)) complexes (n = 3, L(3) = 1,3-bis(2'-thiazolylimino)isoindoline and n = 5, L(5) = 1,3-bis(4-methyl-2'-piridylimino)isoindoline) are five-coordinate, trigonal bipyramidal with the isoindoline ligands occupying the two axial and one equatorial positions meridionally. These compounds served as precursors for catechol dioxygenase models that were formed in solution upon addition of 3,5-di-tert-butylcatechol (H(2)DBC) and excess triethylamine. These adducts react with dioxygen in N,N-dimethylformamide, and the analysis of the products by chromatography and mass spectrometry showed high intradiol over extradiol selectivity (the intradiol/extradiol product ratios varied between 46.5 and 6.5). Kinetic measurements were performed by following the change in the intensity of the catecholate to iron ligand-to-metal charge transfer (LMCT) band, the energy of which is influenced by the isoindolinate-ligand (827-960 nm). In combination with electrochemical investigations the kinetic studies revealed an inverse trend between reaction rates and oxidation potentials associated with the coordinated DBC(2-). On the basis of these results, a substrate activation mechanism is suggested for this system in which the geometry of the peroxide-bridged intermediate may be of key importance in regioselectivity. PMID:23320898

Váradi, Tünde; Pap, József S; Giorgi, Michel; Párkányi, László; Csay, Tamás; Speier, Gábor; Kaizer, József

2013-02-01

268

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. PMID:19365560

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

269

PLS modelling of structure-activity relationships of catechol O-methyltransferase inhibitors.  

PubMed

Quantitative structure-activity analysis was carried out for in vitro inhibition of rat brain soluble catechol O-methyltransferase by a series (N = 99) of 1,5-substituted-3,4-dihydroxybenzenes using computational chemistry and multivariate PLS modelling of data sets. The molecular structural descriptors (N = 19) associated with the electronics of the catecholic ring and sizes of substituents were derived theoretically. For the whole set of molecules two separate PLS models have to be used. A PLS model with two significant (crossvalidated) model dimensions describing 82.2% of the variance in inhibition activity data was capable of predicting all molecules except those having the largest R1 substituent or having a large R5 substituent compared to the NO2 group. The other PLS model with three significant (crossvalidated) model dimensions described 83.3% of the variance in inhibition activity data. This model could not handle compounds having a small R5 substituent, compared to the NO2 group, or the largest R1 substituent. The predictive capability of these PLS models was good. The models reveal that inhibition activity is nonlinearly related to the size of the R5 substituent. The analysis of the PLS models also shows that the binding affinity is greatly dependent on the electronic nature of both R1 and R5 substituents. The electron-withdrawing nature of the substituents enhances inhibition activity. In addition, the size of the R1 substituent and its lipophilicity are important in the binding of inhibitors. The size of the R1 substituent has an upper limit. On the other hand, ionized R1 substituents decrease inhibition activity. PMID:1517777

Lotta, T; Taskinen, J; Bäckström, R; Nissinen, E

1992-06-01

270

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

SciTech Connect

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

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

1996-03-01

271

Crystal structures of d-alanine-d-alanine ligase from Xanthomonas oryzae pv. oryzae alone and in complex with nucleotides.  

PubMed

D-Alanine-D-alanine ligase (DDL) catalyzes the biosynthesis of d-alanyl-d-alanine, an essential bacterial peptidoglycan precursor, and is an important drug target for the development of antibacterials. We determined four different crystal structures of DDL from Xanthomonas oryzae pv. oryzae (Xoo) causing Bacteria Blight (BB), which include apo, ADP-bound, ATP-bound, and AMPPNP-bound structures at the resolution between 2.3 and 2.0 Ĺ. Similarly with other DDLs, the active site of XoDDL is formed by three loops from three domains at the center of enzyme. Compared with d-alanyl-d-alanine and ATP-bound TtDDL structure, the ?-phosphate of ATP in XoDDL structure was shifted outside toward solution. We swapped the ?-loop (loop3) of XoDDL with those of Escherichia coli and Helicobacter pylori DDLs, and measured the enzymatic kinetics of wild-type XoDDL and two mutant XoDDLs with the swapped ?-loops. Results showed that the direct interactions between ?-loop and other two loops are essential for the active ATP conformation for D-ala-phosphate formation. PMID:24440607

Doan, Thanh Thi Ngoc; Kim, Jin-Kwang; Ngo, Ho-Phuong-Thuy; Tran, Huyen-Thi; Cha, Sun-Shin; Min Chung, Kyung; Huynh, Kim-Hung; Ahn, Yeh-Jin; Kang, Lin-Woo

2014-03-01

272

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

PubMed Central

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

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

2013-01-01

273

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. PMID:21726058

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

2011-01-01

274

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

2013-11-01

275

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

PubMed

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

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

2013-01-01

276

Increased xanthine oxidase in the skin of preeclamptic women.  

PubMed

Xanthine oxioreductase is the holoenzyme responsible for terminal purine catabolism. Under conditions of metabolic stress or heightened proinflammatory cytokine production, this enzyme is preferentially in its oxidized form, xanthine oxidase, with catalytic action that generates uric acid and the free radical superoxide. As preeclampsia is characterized by heightened inflammation, oxidative stress, and hyperuricemia, it has been proposed that xanthine oxidase plays a pivotal role in this hypertensive disorder of pregnancy. We sought to determine whether xanthine oxidase protein content was higher in maternal tissue of preeclamptic mothers, compared to healthy pregnant controls, using immunohistochemical analysis of skin biopsies. We further compared xanthine oxidase immunoreactivity in skin biopsies from preeclamptic women and patients with several inflammatory conditions. In preeclamptic women, intense xanthine oxidase immunoreactivity was present within the epidermis. By contrast, only very faint xanthine oxidase staining was observed in skin biopsies from healthy pregnant controls. Further, a role for inflammation in the increase of xanthine oxidase was suggested by similar findings of heightened xanthine oxidase immunoreactivity in the skin biopsies from nonpregnant individuals diagnosed with conditions of systemic inflammation. The finding of increased xanthine oxidase in maternal tissue, most likely as the result of heightened maternal inflammation, suggests maternal xanthine oxidase as a source of free radical and uric acid generation in preeclampsia. PMID:19196876

Bainbridge, Shannon A; Deng, Jau-Shyong; Roberts, James M

2009-05-01

277

INCREASED XANTHINE OXIDASE IN THE SKIN OF PREECLAMPTIC WOMEN  

PubMed Central

Xanthine oxioreductase is the holoenzyme responsible for terminal purine catabolism. Under conditions of metabolic stress or heightened pro-inflammatory cytokine production this enzyme is preferentially in it’s oxidized form, xanthine oxidase, with catalytic action that generates uric acid and the free radical superoxide. As preeclampsia is characterized by heightened inflammation, oxidative stress and hyperuricemia it has been proposed that xanthine oxidase plays a pivotal role in this hypertensive disorder of pregnancy. We sought to determine whether xanthine oxidase protein content was higher in maternal tissue of preeclamptic mothers, compared to healthy pregnant controls, using immunohistochemical analysis of skin biopsies. We further compared xanthine oxidase immunoreactivity in skin biopsies from preeclamptic women and patients with several inflammatory conditions. In preeclamptic women, intense xanthine oxidase immunoreactivity was present within the epidermis. By contrast, only very faint xanthine oxidase staining was observed in skin biopsies from healthy pregnant controls. Further, a role for inflammation in the increase of xanthine oxidase was suggested by similar findings of heightened xanthine oxidase immunoreactivity in the skin biopsies from non-pregnant individuals diagnosed with conditions of systemic inflammation. The finding of increased xanthine oxidase in maternal tissue, most likely as the result of heightened maternal inflammation, suggest maternal xanthine oxidase as a source of free radical and uric acid generation in preeclampsia. PMID:19196876

Bainbridge, Shannon A.; Deng, Jau-Shyong; Roberts, James M.

2010-01-01

278

Lysyl oxidase expression and inhibition in uveal melanoma.  

PubMed

Lysyl oxidase is a marker of poor prognosis in several malignancies and is hypothesized to promote a migratory phenotype in hypoxic breast carcinomas. This study aims to characterize the expression of the lysyl oxidase and lysyl oxidase-like proteins in human uveal melanoma cell lines and archival choroidal melanomas using immunohistochemistry. The transcriptional control of lysyl oxidase will also be investigated under simulated hypoxic conditions using cobalt chloride. Lastly, changes in cellular proliferation and invasion will be assessed after the treatment of cell lines with beta-aminopropionitrile, a lysyl oxidase catalytic inhibitor. Retrospective analysis of lysyl oxidase expression in primary human uveal melanoma showed 82% (27 of 33) of tumors being stained positive. High lysyl oxidase expression correlated with the aggressive epithelioid cell type and was associated with shorter metastasis-free survival. Simulated hypoxia resulted in a significant increase in lysyl oxidase mRNA expression. Inhibiting lysyl oxidase's catalytic activity significantly reduced cellular invasion but had no effect on cell proliferation. Our study is the first to show lysyl oxidase expression in primary choroidal melanomas. This protein may represent a potential therapeutic target that warrants further study in this malignancy. PMID:20179655

Abourbih, Daniel A; Di Cesare, Sebastian; Orellana, Maria E; Antecka, Emilia; Martins, Claudia; Petruccelli, Luca A; Burnier, Miguel N

2010-04-01

279

Selected furanochalcones as inhibitors of monoamine oxidase.  

PubMed

The validity of the chalcone scaffold for the design of inhibitors of monoamine oxidase has previously been illustrated. In a systematic attempt to investigate the effect of heterocyclic substitution on the monoamine oxidase inhibitory properties of this versatile scaffold, a series of furanochalcones were synthesized. The results demonstrate that these furan substituted phenylpropenones exhibited moderate to good inhibitory activities towards MAO-B, but showed weak or no inhibition of the MAO-A enzyme. The most active compound, 2E-3-(5-chlorofuran-2-yl)-1-(3-chlorophenyl)prop-2-en-1-one, exhibited an IC50 value of 0.174 ?M for the inhibition of MAO-B and 28.6 ?M for the inhibition of MAO-A. Interestingly, contrary to data previously reported for chalcones, these furan substituted derivatives acted as reversible inhibitors, while kinetic analysis revealed a competitive mode of binding. PMID:23860591

Robinson, Sarel J; Petzer, Jacobus P; Petzer, Anél; Bergh, Jacobus J; Lourens, Anna C U

2013-09-01

280

Natural Compounds as Modulators of NADPH Oxidases  

PubMed Central

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

2013-01-01

281

Genomic analysis of Xanthomonas oryzae isolates from rice grown in the United States reveals substantial divergence from known X. oryzae pathovars.  

PubMed

The species Xanthomonas oryzae is comprised of two designated pathovars, both of which cause economically significant diseases of rice in Asia and Africa. Although X. oryzae is not considered endemic in the United States, an X. oryzae-like bacterium was isolated from U.S. rice and southern cutgrass in the late 1980s. The U.S. strains were weakly pathogenic and genetically distinct from characterized X. oryzae pathovars. In the current study, a draft genome sequence from two U.S. Xanthomonas strains revealed that the U.S. strains form a novel clade within the X. oryzae species, distinct from all strains known to cause significant yield loss. Comparative genome analysis revealed several putative gene clusters specific to the U.S. strains and supported previous reports that the U.S. strains lack transcriptional activator-like (TAL) effectors. In addition to phylogenetic and comparative analyses, the genome sequence was used for designing robust U.S. strain-specific primers, demonstrating the usefulness of a draft genome sequence in the rapid development of diagnostic tools. PMID:21515727

Triplett, L R; Hamilton, J P; Buell, C R; Tisserat, N A; Verdier, V; Zink, F; Leach, J E

2011-06-01

282

Creatinine Inhibits D-Amino Acid Oxidase  

Microsoft Academic Search

Inhibition of D-amino acid oxidase (DAO) activity by various uremic retention products and guanidino compounds was investigated. Creatinine (CTN) was found to inhibit DAO at a similar concentration in the sera of uremic patients. The inhibition was competitive and the Ki value was 2.7 mM. Moreover, CTN was shown to interact with flavin adenine dinucleotide (FAD), a coenzyme of DAO.

Y. Nohara; J. Suzuki; T. Kinoshita; M. Watanabe

2002-01-01

283

Defensive Roles of Polyphenol Oxidase in Plants  

Microsoft Academic Search

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

C. Peter Constabel; Raymond Barbehenn

284

Ligand interactions with galactose oxidase: mechanistic insights.  

PubMed Central

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

Whittaker, M M; Whittaker, J W

1993-01-01

285

XANTHINE OXIDASE ACTIVITY IN REGENERATING LIVER*  

E-print Network

The xanthine oxiclase activity of mouse regenerating liver has been shown to be elevated during the period of rapid liver growth and proliferation. This increase is evident when the enzyme activity is expressed per unit wet tissue weight, per unit nitrogen, or per cell. The adrenal cortex probably plays only a minor role in implementing this phenomenon. Further augmentation of the xanthine oxidase level of regenerating liver is not induced by the administration of large quantities of the substrate, xanthine, to the animal.

Muriel Feigelson; Philip Feigelson; Paul; R. Gross; Ab Stract

286

Oxidase Reactions of Tomato Anionic Peroxidase 1  

PubMed Central

Tomato (Lycopersicon esculentum Mill) anionic peroxidase was found to catalyze oxidase reactions with NADH, glutathione, dithiothreitol, oxaloacetate, and hydroquinone as substrates with a mean activity 30% that of horseradish peroxidase; this is in contrast to the negligible activity of the tomato enzyme as compared to the horseradish enzyme in catalyzing an indoleacetic acid-oxidase reaction with only Mn2+ and a phenol as cofactors. Substitution of Ce3+ for Mn2+ produced an 18-fold larger response with the tomato enzyme than with the horseradish enzyme, suggesting a significant difference in the autocatalytic indoleacetic acid-oxidase reactions with these two enzymes. In attempting to compare enzyme activities with 2,4-dichlorophenol as a cofactor, it was found that reaction rates increased exponentially with both increasing cofactor concentration and increasing enzyme concentration. While the former response may be analogous to allosteric control of enzyme activity, the latter response is contrary to the principle that reaction rate is proportional to enzyme concentration, and additionally makes any comparison of enzyme activity difficult. PMID:16664567

Brooks, James L.

1986-01-01

287

Features and applications of bilirubin oxidases.  

PubMed

Discovered in 1981 by Tanaka and Murao (Agric Biol Chem 45:2383-2384, 1981), bilirubin oxidase (BOD) is a sub-group of multicopper oxidases (MCOs) also utilizing four Cu(+/2+) ions. It catalyzes the oxidation of bilirubin to biliverdin, hence the classification of bilirubin oxidase, and has been primarily used in the determination of bilirubin in serum and thereby in the diagnostic of jaundice. Unlike laccases, the most studied MCOs, BODs display a high activity and stability at neutral pH, a high tolerance towards chloride anions and other chelators, and for some species, a high thermal tolerance. Therefore, BODs could potentially be an alternative to laccase which are so far mainly restricted to applications in acid media. Because of growing interest in BODs for numerous applications under mild pH conditions, based on the number of patents and publications published in the last 5 years, here I will summarize the available data on the biochemical properties of BODs, their occurrence, and their possible biotechnological use in (1) the field of Healthcare for the elaboration of biofuel cells or bilirubin sensors or (2) the field of environmentally desirable applications such as depollution, decolorization of dyes, and pulp bleaching. PMID:22878843

Mano, Nicolas

2012-10-01

288

New route to the mixed valence semiquinone-catecholate based mononuclear FeIII and catecholate based dinuclear MnIII complexes: first experimental evidence of valence tautomerism in an iron complex.  

PubMed

The semiquinone-catecholate based mixed valence complex, [FeIII(bispicen)(Cl4Cat)(Cl4SQ)] x DMF (1), and catecholate based (H2bispictn)[Mn2III(Cl4Cat)4(DMF)2] (2) (bispicen = N,N'-bis(2-pyridylmethyl)-1,2-ethanediamine, bispictn = N,N'-bis(2-pyridylmethyl)-1,3-propanediamine, Cl4Cat = tetrachlorocatecholate dianion, and Cl4SQ = tetrachlorosemiquinone radical anion) were synthesized directly utilizing a facile route. Both the complexes have been characterized by single crystal X-ray diffraction study. The electronic structures have been elucidated by UV-vis-NIR absorption spectroscopy, cyclic voltammetry, EPR, and magnetic properties. The structural as well as spectroscopic features support the mixed valence tetrachlorosemiquinone-tetrachlorocatecholate charge distribution in 1. The ligand based mixed valence state was further confirmed by the presence of an intervalence charge transfer (IVCT) band in the 1900 nm region both in solution and in the solid. The intramolecular electron transfer, a phenomenon known as valence tautomerism (VT), has been followed by electronic absorption spectroscopy. For 1, the isomeric form [FeIII(bispicen)(Cl4Cat)(Cl4SQ)] is favored at low temperature, while at an elevated temperature, the [FeII(bispicen)(Cl4SQ)2] redox isomer dominates. Infrared as well as UV-vis-NIR spectral characterization for 2 suggest that the MnIII(Cat)2- moiety is admixed with its mixed valence semiquinone-catecholate isomer MnII(SQ)(Cat)-, and the electronic absorption spectrum is dominated by the mixed charged species. The origin of the intervalence charge transfer band in the 1900 nm range is associated with the mixed valence form, MnII(Cl4Cat)(Cl4SQ)-. The observation of VT in complex 1 is the first example where a mixed valence semiquinone-catecholate iron(III) complex undergoes intramolecular electron transfer similar to manganese and cobalt complexes. PMID:15360240

Shaikh, Nizamuddin; Goswami, Sanchita; Panja, Anangamohan; Wang, Xin-Yi; Gao, Song; Butcher, Ray J; Banerjee, Pradyot

2004-09-20

289

Monoolein production by triglycerides hydrolysis using immobilized Rhizopus oryzae lipase.  

PubMed

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

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

2014-07-01

290

The amine oxidases of human placenta and pregnancy plasma  

PubMed Central

1. The purification of monoamine oxidase and diamine oxidase from normal human term placental tissue is described. 2. The properties of these enzymes are reported and compared with the properties of unpurified human pregnancy plasma. 3. This comparison shows that the amine oxidase of pregnancy plasma has properties corresponding to purified placental diamine oxidase, suggesting a placental origin for the plasma enzyme system. 4. Detailed kinetic study of the purified placental diamine oxidase suggests that it has a Ping Pong sequence, a mechanism of action and rate-limiting step similar to the diamine oxidase of pig kidney. 5. It is suggested that the enzyme system is important in protecting the foeto-placental unit from excesses of biogenic amines. PMID:4219137

Bardsley, William G.; Crabbe, M. James C.; Scott, Ian V.

1974-01-01

291

Effects of fly ash and Helminthosporium oryzae on growth and yield of three cultivars of rice  

Microsoft Academic Search

A 120-day greenhouse experiment was conducted to study the effects of various fly ash concentrations (0%, 20%, 40%, 60%, 80% and 100% vol\\/vol) with normal field soil and Helminthosporium oryzae on the growth and yield of three cultivars (Pusa Basmati, Pant-4 and Pant-10) of rice, Oryza sativa L. Application of 20% and 40% fly ash with soil caused a significant

Lamabam P Singh; Zaki A Siddiqui

2003-01-01

292

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

293

In vitro and in vivo inhibition of lysyl oxidase byaminopropionitriles  

Microsoft Academic Search

Inhibition of lysyl oxidase (protein?lysine 6?oxidase, EC 1.4.3.13) decreases the rate of collagen and elastin cross?link formation and produces osteolathyrism in animals. Organic nitriles, including ß?aminopropionitrile (BAPN), have been shown to irreversibly inhibit lysyl oxidase in vitro. Both BAPN and 3,3'?iminodipropionitrile (IDPN) have been shown to produce osteolathyric changes when administered to animals. To date compounds that have been reported

Kenneth R. Wilmarth; John R. Froines

1992-01-01

294

Gravity Responsive NADH Oxidase of the Plasma Membrane  

NASA Technical Reports Server (NTRS)

A method and apparatus for sensing gravity using an NADH oxidase of the plasma membrane which has been found to respond to unit gravity and low centrifugal g forces. The oxidation rate of NADH supplied to the NADH oxidase is measured and translated to represent the relative gravitational force exerted on the protein. The NADH oxidase of the plasma membrane may be obtained from plant or animal sources or may be produced recombinantly.

Morre, D. James (Inventor)

2002-01-01

295

Lysyl Oxidases: Expression in the Fetal Membranes and Placenta  

Microsoft Academic Search

The cross-linking of the connective tissues in the fetal membranes and placenta is important for their tensile strength and elasticity. We have studied the expression of lysyl oxidase (LOX) because it is the classical enzyme responsible for the cross-linking of collagen and elastin. We have also studied the two recently described, genetically distinct lysyl oxidase-like genes and proteins, lysyl oxidase-like

S. Hein; S. Y. Yamamoto; K. Okazaki; C. Jourdan-Lesaux; K. Csiszar; G. D. Bryant-Greenwood

2001-01-01

296

PHOTOCHEMICAL ACTION SPECTRUM OF THE TERMINAL OXIDASE OF MIXED FUNCTION OXIDASE SYSTEMS.  

PubMed

The reversal of the carbon monoxide inhibition by bands of monochromatic light was determined for the oxidative demethylation of codeine and monomethyl-4-aminopyrine and the hydroxylation of acetanilide by rat liver microsomes and for the hydroxylation of 17-hydroxyprogesterone at carbon-21 by bovine adrenocortical microsomes. Maximum reversal occurred at 450 millimicrons, the light absorption maximum of the CO compound of the CO-binding pigment of microsomes. The agreement between photochemical action spectrum and spectrophotometric difference spectrum supports the conclusion that the CO-binding pigment is the terminal oxidase of mixed function oxidase systems of mammals. PMID:14221486

COOPER, D Y; LEVIN, S; NARASIMHULU, S; ROSENTHAL, O

1965-01-22

297

Crystallization and preliminary X-ray investigation of a recombinant form of rat catechol O-methyltransferase.  

PubMed

Rat catechol O-methyltransferase cDNA was introduced into an E. coli expression vector pKEX14, which utilizes the inducible T7 promoter. Active and soluble recombinant catechol O-methyltransferase was produced in bacteria and purified to electrophoretic homogeneity by chromatographic procedures. The purified enzyme has been crystallized by the method of vapor diffusion using polyethylene glycol as precipitant. The space group is P3(1)21 or P3(2)21 with a = b = 51.3 A and c = 168.5 A and one molecule in the asymmetric unit. The crystals diffract beyond 3.2 A and are suitable for three-dimensional X-ray structure determination. PMID:1749777

Vidgren, J; Tilgmann, C; Lundström, K; Liljas, A

1991-01-01

298

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

PubMed

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

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

2013-01-01

299

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

PubMed

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

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

2014-01-01

300

Rapid diversification of five Oryza AA genomes associated with rice adaptation.  

PubMed

Comparative genomic analyses among closely related species can greatly enhance our understanding of plant gene and genome evolution. We report de novo-assembled AA-genome sequences for Oryza nivara, Oryza glaberrima, Oryza barthii, Oryza glumaepatula, and Oryza meridionalis. Our analyses reveal massive levels of genomic structural variation, including segmental duplication and rapid gene family turnover, with particularly high instability in defense-related genes. We show, on a genomic scale, how lineage-specific expansion or contraction of gene families has led to their morphological and reproductive diversification, thus enlightening the evolutionary process of speciation and adaptation. Despite strong purifying selective pressures on most Oryza genes, we documented a large number of positively selected genes, especially those genes involved in flower development, reproduction, and resistance-related processes. These diversifying genes are expected to have played key roles in adaptations to their ecological niches in Asia, South America, Africa and Australia. Extensive variation in noncoding RNA gene numbers, function enrichment, and rates of sequence divergence might also help account for the different genetic adaptations of these rice species. Collectively, these resources provide new opportunities for evolutionary genomics, numerous insights into recent speciation, a valuable database of functional variation for crop improvement, and tools for efficient conservation of wild rice germplasm. PMID:25368197

Zhang, Qun-Jie; Zhu, Ting; Xia, En-Hua; Shi, Chao; Liu, Yun-Long; Zhang, Yun; Liu, Yuan; Jiang, Wen-Kai; Zhao, You-Jie; Mao, Shu-Yan; Zhang, Li-Ping; Huang, Hui; Jiao, Jun-Ying; Xu, Ping-Zhen; Yao, Qiu-Yang; Zeng, Fan-Chun; Yang, Li-Li; Gao, Ju; Tao, Da-Yun; Wang, Yue-Ju; Bennetzen, Jeffrey L; Gao, Li-Zhi

2014-11-18

301

Electrocatalytic oxidation of dihydronicotineamide adenine dinucleotide on gold electrode modified with catechol-terminated alkanethiol self-assembly.  

PubMed

Synthesis of a mercaptoundecaneamide derivative having a terminus of catechol is described. FT-IR spectroscopic characterization showed that the new molecular entry simply undergoes molecular self-assembly on Au substrate surfaces promoting intra- and intermolecular hydrogen bonds to form well-packed monolayers. Cyclic voltammetric (CV) measurements on the monolayer-modified Au electrode revealed that the surface adlayer possesses specific electrochemical activity due to the reversible catechol/o-quinone redox reaction having characteristics of a surface process and also pH-dependence in its formal potential (59 mV per pH). Detailed analysis of CVs gave fundamental electrochemical parameters including the electroactive surface coverage (0.20-0.24 nmol cm(-2)), the transfer coefficients (0.24 in oxidation and 0.81 in reduction), and also the electron transfer rate constant (1.10-2.76 s(-1)). These data were almost consistent to those seen in literature. We have also found that the catechol monolayer modified electrode exhibits an electrocatalytic function in NADH oxidation. That is, the faradaic current appeared reinforcingly at around the same potential where catechol function is oxidized in the monolayer and increased with an increase in the NADH concentration from 1 to 5 mM, and then reached to a plateau indicating a catalyzed reaction pathway. Detailed analyses revealed that the present system could be characterized by its weak stability of the intermediate compound formed and prompt reaction rate compared with the previously reported chemically modified electrode (CME) systems. We think this type of achievement should be important for the basics of biosensors that rely on dehydrogenase enzymes. PMID:18539170

Nakano, Koji; Ohkubo, Kimihiko; Taira, Hiroaki; Takagi, Makoto; Imato, Toshihiko

2008-06-30

302

Catechol-O-Methyltransferase (COMT) Val 108\\/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\\u000a performance in healthy and schizophrenic adults. Since several of the cognitive functions typically deficient in children\\u000a with Attention Deficit Hyperactivity Disorder (ADHD) are mediated by prefrontal dopamine (DA) mechanisms, we investigated\\u000a the relationship between a functional

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

303

The Catechol-O-Methyltransferase Polymorphism: Relations to the Tonic–Phasic Dopamine Hypothesis and Neuropsychiatric Phenotypes  

Microsoft Academic Search

Diverse phenotypic associations with the catechol-O-methyltransferase (COMT) Val158Met polymorphism have been reported. We suggest that some of the complex effects of this polymorphism be understood from the perspective of the tonic–phasic dopamine (DA) hypothesis. We hypothesize that the COMT Met allele (associated with low enzyme activity) results in increased levels of tonic DA and reciprocal reductions in phasic DA in

Robert M Bilder; Jan Volavka; Herbert M Lachman; Anthony A Grace

2004-01-01

304

Simple amperometric detector for microchip capillary electrophoresis, and its application to the analysis of dopamine and catechol  

Microsoft Academic Search

We report on a simple amperometric detector for use in microchip capillary electrophoresis. A disposable syringe serves as\\u000a the electrode holder that is fixed at the outlet of the separation channel. A carbon paste electrode is used to detect dopamine\\u000a (DA) and catechol (CA) after electrophoretic separation. The two model analytes were well separated within 60 s. The response\\u000a is

Xinchun Li; Jianbin Pan; Fan Yang; Jun Feng; Jinyuan Mo; Zuanguang Chen

2011-01-01

305

Pharmacogenetics of Modafinil After Sleep Loss: Catechol-O-Methyltransferase Genotype Modulates Waking Functions But Not Recovery Sleep  

Microsoft Academic Search

Sleep loss impairs waking functions and is homeostatically compensated in recovery sleep. The mechanisms underlying the consequences of prolonged wakefulness are unknown. The stimulant modafinil may promote primarily dopaminergic neurotransmission. Catechol-O-methyltransferase (COMT) catalyzes the breakdown of cerebral dopamine. A functional Val158Met polymorphism reduces COMT activity, and Val\\/Val homozygous individuals presumably have lower dopaminergic signaling in the prefrontal cortex than do

S Bodenmann; S Xu; UFO Luhmann; M Arand; W Berger; HH Jung; HP Landolt

2009-01-01

306

Genotype Determining Low Catechol-O-Methyltransferase Activity as a Risk Factor for Obsessive-Compulsive Disorder  

Microsoft Academic Search

In the present study, we address the role of the gene for catechol-O-methyltransferase (COMT), a key modulator of dopaminergic and noradrenergic neurotransmission, in the genetic predisposition to obsessive-compulsive disorder (OCD). We show that a common functional allele of this gene, which results in a 3- to 4-fold reduction in enzyme activity, is significantly associated in a recessive manner with susceptibility

Maria Karayiorgou; Margaret Altemus; Brandi L. Galke; David Goldman; Dennis L. Murphy; Jurg Ott; Joseph A. Gogos

1997-01-01

307

Metal chelate affinity to immobilize horseradish peroxidase on functionalized agarose\\/CNTs composites for the detection of catechol  

Microsoft Academic Search

The paper reports a novel amperometric biosensor for catechol based on immobilization of a highly sensitive horseradish peroxidase\\u000a by affinity interactions on metal chelate-functionalized agarose\\/carbon nanotubes composites. Metal chelate affinity takes\\u000a advantage of the affinity of Ni2+ ions to bind strongly and reversibly to histidine or cysteine tails found on the surface of the horseradish peroxidase. Thus,\\u000a enzymes with such

XinMan Tu; ShengLian Luo; XuBiao Luo; YingJie Zhao; Li Feng; JingHong Li

2011-01-01

308

Vapour-phase selective O-methylation of catechol with methanol over Ti-containing aluminium phosphate catalysts  

Microsoft Academic Search

Vapour-phase O-methylation of catechol with methanol has been investigated over Ti-containing aluminium phosphate catalysts (denoted as Al0.77TixP, where x is between 0 and 1.15) prepared by non-uniform precipitation method. The catalytic activities increase with the increase of Ti\\/P ratio in the range 0–0.23, while further increase of Ti content leads to the decrease of activities. Meanwhile, the selectivity to guaiacol

Xiaomei Zhu; Xuemei Li; Mingjun Jia; Gang Liu; Wenxiang Zhang; Dazhen Jiang

2005-01-01

309

Differential Pulse Voltammetric Determination of L-Cysteine after Cyclic Voltammetry in Presence of Catechol with Glassy Carbon Electrode  

Microsoft Academic Search

An electrochemical method of determination of cysteine has been developed in the solution containing catechol as indicator. Nucleophilic addition of the thiol species to the electrogenerated o-quinone results in the formation of an o-quinone-cysteine adduct which easily accumulates at the surface of the electrode in the acidic solution. Therefore, the conduct of cyclic voltammetry leads to the amplification of the

Xinfei Liu; Hui Lv; Qiaohua Sun; Yan Zhong; Jian Zhao; Jiabao Fu; Mi Lin; Jianguo Wang

2012-01-01

310

Characterization of Three Putative Monoamine Oxidase Genes in Caenorhabditis elegans.  

E-print Network

??Monoamine neurotransmitters like dopamine and serotonin regulate neuronal function and behavior in animals. In vertebrates, monoamine oxidase (MAO) degrades monoamines. We investigated the function of… (more)

Kaushal, Setu

2008-01-01

311

Concentration dependent effects of commonly used pesticides on activation versus inhibition of the quince (Cydonia Oblonga) polyphenol oxidase.  

PubMed

Polyphenol oxidase (PPO) catalyzes the oxidation of o-diphenols to their respective quinones which undergo autopolymerization and form dark pigments. The interaction of PPO with various substrates and effectors remains the focus of intensive investigations due to the enzyme's key role in pigments biosynthesis including animal melanogenesis and fruit/fungi enzymatic browning. In this study, the effect of a range of commonly used pesticides on the enzyme activity has been evaluated using the purified quince (Cydonia oblonga Miller) PPO. The biochemical analysis showed that, in the presence of high pesticide concentrations, the enzyme was competitively inhibited, particularly with benomyl, carbaryl, deltamethrine and parathion methyl for which inhibition constants (K(i)) were 8.3, 5.7, 12 and 4 microM, respectively. At lower pesticide concentrations (2-10 microM), however, the catecholase activity was significantly activated (p<0.01), suggesting a homotropic behavior of these chemical compounds. Furthermore, the use of in silico structure-based analyses, known as computational docking, highlighted the nature of the PPO-pesticides interactions and confirmed the in vitro observations. Catechol substrate and parathion methyl inhibitor showed lower total energy scores of -120.06 and -117.4 3 kcal mol(-1), indicating that these ligands had higher PPO-binding affinities. The obtained data bring to light new pesticide functional features of great interest in the medicinal, agro-chemical and environmental circles. PMID:20060877

Fattouch, Sami; Raboudi-Fattouch, Faten; Ponce, José Vicente Gil; Forment, Josep Vicent; Lukovic, Dunja; Marzouki, Nejib; Vidal, Daniel Ramón

2010-03-01

312

Molecular cloning and characterization of a novel metagenome-derived multicopper oxidase with alkaline laccase activity and highly soluble expression.  

PubMed

Lac591, a gene encoding a novel multicopper oxidase with laccase activity, was identified through activity-based functional screening of a metagenomic library from mangrove soil. Sequence analysis revealed that lac591 encodes a protein of 500 amino acids with a predicted molecular mass of 57.4 kDa. Lac591 was overexpressed heterologously as soluble active enzyme in Escherichia coli and purified, giving rise to 380 mg of purified enzyme from 1 l induced culture, which is the highest expression report for bacterial laccase genes so far. Furthermore, the recombinant enzyme demonstrated activity toward classical laccase substrates syringaldazine (SGZ), guaiacol, and 2, 6-dimethoxyphenol (2, 6-DMP). The purified Lac591 exhibited maximal activity at 55 degrees C and pH 7.5 with guaiacol as substrate and was found to be stable in the pH range of 7.0-10.0. The substrate specificity on different substrates was studied with the purified enzyme, and the optimal substrates were in the order of 2, 6-DMP > catechol > alpha-naphthol > guaiacol > SGZ > 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid). The alkaline activity and highly soluble expression of Lac591 make it a good candidate of laccases in industrial applications for which classical laccases are unsuitable, such as biobleaching of paper pulp and dyestuffs processing. PMID:20358193

Ye, Mao; Li, Gang; Liang, Wei Qu; Liu, Yu Huan

2010-07-01

313

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

SciTech Connect

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

Griffiths, J.C.

1986-01-01

314

Amperometric catechol biosensor based on laccase immobilized on nitrogen-doped ordered mesoporous carbon (N-OMC)/PVA matrix  

NASA Astrophysics Data System (ADS)

A functionalized nitrogen-containing ordered mesoporous carbon (N-OMC), which shows good electrical properties, was synthesized by the carbonization of polyaniline inside a SBA-15 mesoporous silica template. Based on this, through entrapping laccase onto the N-OMC/polyvinyl alcohol (PVA) film a facilely fabricated amperometric biosensor was developed. Laccase from Trametes versicolor was assembled on a composite film of a N-OMC/PVA modified Au electrode and the electrochemical behavior was investigated. The results indicated that the N-OMC modified electrode exhibits electrical properties towards catechol. The optimum experimental conditions of a biosensor for the detection of catechol were studied in detail. Under the optimal conditions, the sensitivity of the biosensor was 0.29 A*M-1 with a detection limit of 0.31 ?M and a linear detection range from 0.39 ?M to 8.98 ?M for catechol. The calibration curve followed the Michaelis-Menten kinetics and the apparent Michaelis-Menten \\left( K_{M}^{app} \\right) was 6.28 ?M. This work demonstrated that the N-OMC/PVA composite provides a suitable support for laccase immobilization and the construction of a biosensor.

Guo, Meiqing; Wang, Hefeng; Huang, Di; Han, Zhijun; Li, Qiang; Wang, Xiaojun; Chen, Jing

2014-06-01

315

Biomimetic PEG-catecholates for stabile antifouling coatings on metal surfaces: applications on TiO2 and stainless steel.  

PubMed

Trimeric catecholates have been designed for the stable immobilization of effector molecules on metal surfaces. The design of these catecholates followed a biomimetic approach and was inspired by natural multivalent metal binders, such as mussel adhesion proteins (MAPs) and siderophores. Three catecholates have been conjugated to central scaffolds based on adamantyl or trisalkylmethyl core structures. The resulting triscatecholates have been immobilized on TiO2 and stainless steel. In a proof of concept study we have demonstrated the high stability of the resulting nanolayers at neutral and slightly acidic pH. Furthermore, polyethylene glycol (PEG) conjugates of our triscatecholates have been synthesized and were immobilized on TiO2 and stainless steel. The PEG coated surfaces showed excellent antifouling properties upon exposure to human blood and bacteria as demonstrated by fluorescence microscopy, ellipsometry and a bacterial assay with Staphylococcus epidermidis. In addition, our PEG-triscatecholates showed no cytotoxicity against bone-marrow stem cells on TiO2. PMID:24632391

Khalil, Faiza; Franzmann, Elisa; Ramcke, Julian; Dakischew, Olga; Lips, Katrin S; Reinhardt, Alexander; Heisig, Peter; Maison, Wolfgang

2014-05-01

316

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

PubMed Central

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

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

2014-01-01

317

AGB1 and PMR5 contribute to PEN2-mediated preinvasion 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. Here, we investigated interactions between Arabidopsis thaliana and M. oryzae to identify the genetic basis of NHR. In A. thaliana accessions, preinvasion resistance to M. oryzae in Col-0 was stronger than that of Ler. To examine the genetic basis underlying the natural variation in the responses, we used a well-established set of recombinant inbred lines (RIL) derived from a Col x Ler cross and identified three quantitative trait loci that govern the expression of NHR in A. thaliana against M. oryzae. Among the penetration (pen) mutants, only the pen2 mutant allowed increased penetration into epidermal cells by M. oryzae. Double mutant analysis indicated that AGB1 and PMR5 contribute to PEN2-mediated preinvasion resistance to M. oryzae in A. thaliana, suggesting a complex genetic network regulating the resistance. Our results demonstrate that A. thaliana can be used to study mechanisms of NHR to M. oryzae. PMID:19810803

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

2009-11-01

318

The human lysyl oxidase-like 2 protein functions as an amine oxidase toward collagen and elastin  

Microsoft Academic Search

The lysyl oxidase-like 2 (LOXL2) protein is a human paralogue of lysyl oxidase (LOX) that functions as an amine oxidase for\\u000a formation of lysine-derived cross-links found in collagen and elastin. In addition to the C-terminal domains characteristic\\u000a to the LOX family members, LOXL2 contains four scavenger receptor cysteine-rich (SRCR) domains in the N-terminus. In order\\u000a to assess the amine oxidase

Young-Mi Kim; Eun-Cheol Kim; Youngho Kim

2011-01-01

319

Bienzyme biosensors for glucose, ethanol and putrescine built on oxidase and sweet potato peroxidase  

Microsoft Academic Search

Amperometric biosensors for glucose, ethanol, and biogenic amines (putrescine) were constructed using oxidase\\/peroxidase bienzyme systems. The H2O2 produced by the oxidase in reaction with its substrate is converted into a measurable signal via a novel peroxidase purified from sweet potato peels. All developed biosensors are based on redox hydrogels formed of oxidases (glucose oxidase, alcohol oxidase, or amine oxidase) and

Jaime Castillo; Szilveszter Gáspár; Ivan Sakharov; Elisabeth Csöregi

2003-01-01

320

Catechol-o-methyltransferase genotype and childhood trauma may interact to impact schizotypal personality traits.  

PubMed

We attempt to identify gene by childhood abuse interactions which predispose to the development of schizotypal traits in a familial bipolar disorder (BD) sample. Self-report measures of schizotypal personality traits (Schizotypal Personality Scale) and childhood maltreatment (Childhood Trauma Questionnaire) were administered to 222 participants from 44 families with BD. Variants of catechol-o-methyltransferase (COMT) and four other dopamine pathway-related genes: DRD4, DRD2,MAOA, and SLC6A3, were typed. BD type I (BD I) subjects scored significantly higher than their unaffected relatives on the Schizotypal Personality Scale. The val allele of the Val158 Met polymorphism of the COMT gene was associated with increased schizotypal personality trait scores in individuals exposed to higher levels of self-reported childhood trauma (p < 0.05). There was no direct effect of the val158met polymorphism on schizotypal personality traits. Further, no passive correlation between COMT genotype and childhood trauma was found. We raise the possibility that genetically-driven variation in COMT may interact with childhood trauma to contribute to the risk of developing schizotypal personality traits. PMID:20033274

Savitz, Jonathan; van der Merwe, Lize; Newman, Timothy K; Stein, Dan J; Ramesar, Raj

2010-05-01

321

Mussel inspired modification of polypropylene separators by catechol/polyamine for Li-ion batteries.  

PubMed

Inspired by the remarkable adhesion of mussel, dopamine, a mimicking adhesive molecule, has been widely used for surface modification of various materials ranging from organic to inorganic. However, dopamine and its derivatives are expensive which impede their application in large scale. Herein, we replaced dopamine with low-cost catechol and polyamine (only 8% of the cost of dopamine), which could be polymerized in an alkaline solution and deposited on the surfaces of various materials. By using this cheap and simple modification method, polypropylene (PP) separator could be transformed from hydrophobic to hydrophilic, while the pore structure and mechanical property of the separator remained intact. The uptake of electrolyte increased from 80% to 270% after the hydrophilic modification. Electrochemical studies demonstrated that battery with the modified PP separator had a better Coulombic efficiency (80.9% to 85.3%) during the first cycle at a current density of 0.1 C, while the discharging current density increased to 15 C and the discharge capacity increased by 1.4 times compared to the battery using the bare PP separator. Additionally, the modification allowed excellent stability during manifold cycles. This study provides new insights into utilizing low-cost chemicals to mimic the mussel adhesion and has potential practical application in many fields. PMID:24684271

Wang, Hao; Wu, Junjie; Cai, Chao; Guo, Jing; Fan, Haosen; Zhu, Caizhen; Dong, Haixia; Zhao, Ning; Xu, Jian

2014-04-23

322

Analysis of Oxidative Stress Status, Catalase and Catechol-O-Methyltransferase Polymorphisms in Egyptian Vitiligo Patients  

PubMed Central

Vitiligo is the most common depigmentation disorder of the skin. Oxidative stress is implicated as one of the probable events involved in vitiligo pathogenesis possibly contributing to melanocyte destruction. Evidence indicates that certain genes including those involved in oxidative stress and melanin synthesis are crucial for development of vitiligo. This study evaluates the oxidative stress status, the role of catalase (CAT) and catechol-O-Methyltransferase (COMT) gene polymorphisms in the etiology of generalized vitiligo in Egyptians. Total antioxidant capacity (TAC) and malondialdehyde (MDA) levels as well as CAT exon 9 T/C and COMT 158 G/A polymorphisms were determined in 89 patients and 90 age and sex-matched controls. Our results showed significantly lower TAC along with higher MDA levels in vitiligo patients compared with controls. Meanwhile, genotype and allele distributions of CAT and COMT polymorphisms in cases were not significantly different from those of controls. Moreover, we found no association between both polymorphisms and vitiligo susceptibility. In conclusion, the enhanced oxidative stress with the lack of association between CAT and COMT polymorphisms and susceptibility to vitiligo in our patients suggest that mutations in other genes related to the oxidative pathway might contribute to the etiology of generalized vitiligo in Egyptian population. PMID:24915010

Mehaney, Dina A.; Darwish, Hebatallah A.; Hegazy, Rehab A.; Nooh, Mohammed M.; Tawdy, Amira M.; Gawdat, Heba I.; El-Sawalhi, Maha M.

2014-01-01

323

[Effect of Catechol-O-methyltransferase deficiency on reinforcing effects of cocaine (experimental study)].  

PubMed

Catechol-O-methyltransferase (COMT) remains an important regulatory element in prefrontal cortex dopamine homeostasis. The literature data suggest that individual differences in COMT activity (Val158Met polymorphism) might have indirect downstream effects on the reward system. The aim of the present study was to examine whether COMT deletion affects reinforcing effects of cocaine in mice. The study was conducted in male mice with homozygous COMT deletion as well as their C57BL/6J wild-type littermates. Animals were trained to nose-poke to receive response-contingent intravenous infusions of cocaine (0.3 mg/kg per infusion; final schedule of reinforcement - fixed ratio (FR) 3 time out 30 s). Following the initial acquisition phase, cocaine self-administration dose-effect functions (0.03, 0.1, 0.3, 1, and 3 mg/kg per infusion) were determined under FR3 and progressive ratio (PR) schedules of reinforcement. Cocaine dose-dependently maintained responding under FR3 and PR schedule of reinforcement when the unit dose of cocaine was varied across the sessions. The total cocaine intake did not differ in COMT deletion mice and wild-type mice. The results of this study suggest that individual differences in COMT activity do not affect primary reinforcing effects of cocaine in mice. PMID:23011431

Mus, L V; Dravolina, O A; Bespalov, A Iu; Käenmäki, M; Talka, R; Salminen, O; Tuominen, R K; Männistiö, P T; Zvartau, E E

2012-01-01

324

Is catechol-o-methyltransferase gene polymorphism a risk factor in the development of premenstrual syndrome?  

PubMed Central

Objective The objective of this study was to investigate whether there was a correlation between catechol-o-methyltransferase (COMT) gene polymorphism, which is believed to play a role in the etiology of psychotic disorders, and premenstrual syndrome (PMS). Methods Fifty-three women with regular menstrual cycles, aged between 18 and 46 years and diagnosed with PMS according to the American Congress of Obstetrics and Gynecology criteria were included in this study as the study group, and 53 healthy women having no health problems were selected as the controls. Venous blood was collected from all patients included in the study and kept at -18? prior to analysis. Results There was no significant difference between the groups in terms of demographic features such as age, body mass index, number of pregnancies, parity, and number of children. No statistically significant difference was observed in terms of COMT gene polymorphism (p=0.61) between women in the PMS and the control groups. However, a significant difference was found between arthralgia, which is an indicator of PMS, and low-enzyme activity COMT gene (Met/Met) polymorphism (p=0.04). Conclusion These results suggested that there was no significant relationship between PMS and COMT gene polymorphism. Since we could not find a direct correlation between the COMT gene polymorphism and PMS, further studies including alternative neurotransmitter pathways are needed to find an effective treatment for this disease. PMID:25045629

Deveci, Esma Ozturk; Selek, Salih; Camuzcuoglu, Aysun; Hilali, Nese Gul; Camuzcuoglu, Hakan; Erdal, Mehmet Emin; Vural, Mehmet

2014-01-01

325

Colloidal stability of iron oxide nanocrystals coated with a PEG-based tetra-catechol surfactant.  

PubMed

Long-term colloidal stability of magnetic iron oxide nanoparticles (NPs) is an important goal that has not yet been fully achieved. To make an advance in our understanding of the colloidal stability of iron oxide NPs in aqueous media, we prepared NPs comprising a monodisperse (13 nm) iron oxide core coated with a PEG-based (PEG: polyethyleneglycol) surfactant. This consists of a methoxy-terminated PEG chain (MW = 5000 Da) bearing four catechol groups via a diethylenetriamine linker. The surfactant was grafted onto the nanocrystals by ligand exchange monitored by infrared spectroscopy. The colloidal stability of these nanoparticles was probed by monitoring the time evolution of the Z-average intensity-weighted radius R(h) and volume-weighted size distribution P(v) obtained from analysis of dynamic light scattering data. The nanoparticles showed no sign of aggregation for four months in deionized water at room temperature and also when subjected to thermal cycling between 25 and 75?°C. In 0.01 M PBS (phosphate buffered saline), aggregation (if any) is slow and partial; after 66 h, about 50% of NPs have not aggregated. Aggregation is more effective in 0.15 M NH(4)AcO buffer, where isolated particles are not observed after 66 h, and especially in acidic NH(4)AcO/AcOH buffer, where aggregation is complete within 1 h and precipitation is observed. The differing stability of the NPs in the above aqueous media is closely related to their ? potential. PMID:23416923

Mondini, Sara; Drago, Carmelo; Ferretti, Anna M; Puglisi, Alessandra; Ponti, Alessandro

2013-03-15

326

Synthesis, Characterization, and Preliminary Investigation of Cell Interaction of Magnetic Nanoparticles with Catechol-Containing Shells  

NASA Astrophysics Data System (ADS)

Superparamagnetic iron oxide cores were synthesized by co-precipitation of Fe(II) and Fe(III) salts and subsequently stabilized by coating with different catechols (levodopa, dopamine, hydrocaffeic acid, dopamine-containing carboxymethyl dextran) known to act as high-affinity, bidentate ligands for Fe(III). The prepared stable magnetic fluids were characterized with regard to their chemical composition (content of iron and shell material, Fe(II)/Fe(III) ratio) and their physical properties (size, surface charge, magnetic parameters). The nanoparticles showed no or only slight cytotoxic effects within 1 and 4 days of incubation with 3T3 fibroblast cells. Preliminary experiments were performed to study the interaction of the prepared nanoparticles with human MCF-7 breast cancer cells and leukocytes. An intense interaction of the MCF-7 cells with these particles was found whereas the leukocytes showed a lower tendency of interaction. Based on these finding, the novel magnetic nanoparticles possess the potential for use in depletion of tumor cells from peripheral blood.

Wagner, Kerstin; Seemann, Thomas; Wyrwa, Ralf; Clement, Joachim H.; Müller, Robert; Nietzsche, Sandor; Schnabelrauch, Matthias

2010-12-01

327

Catechol-O-Methyltransferase val158met Polymorphism Predicts Placebo Effect in Irritable Bowel Syndrome  

PubMed Central

Identifying patients who are potential placebo responders has major implications for clinical practice and trial design. Catechol-O-methyltransferase (COMT), an important enzyme in dopamine catabolism plays a key role in processes associated with the placebo effect such as reward, pain, memory and learning. We hypothesized that the COMT functional val158met polymorphism, was a predictor of placebo effects and tested our hypothesis in a subset of 104 patients from a previously reported randomized controlled trial in irritable bowel syndrome (IBS). The three treatment arms from this study were: no-treatment (“waitlist”), placebo treatment alone (“limited”) and, placebo treatment “augmented” with a supportive patient-health care provider interaction. The primary outcome measure was change from baseline in IBS-Symptom Severity Scale (IBS-SSS) after three weeks of treatment. In a regression model, the number of methionine alleles in COMT val158met was linearly related to placebo response as measured by changes in IBS-SSS (p?=?.035). The strongest placebo response occurred in met/met homozygotes treated in the augmented placebo arm. A smaller met/met associated effect was observed with limited placebo treatment and there was no effect in the waitlist control. These data support our hypothesis that the COMT val158met polymorphism is a potential biomarker of placebo response. PMID:23110189

Hall, Kathryn T.; Lembo, Anthony J.; Kirsch, Irving; Ziogas, Dimitrios C.; Douaiher, Jeffrey; Jensen, Karin B.; Conboy, Lisa A.; Kelley, John M.; Kokkotou, Efi; Kaptchuk, Ted J.

2012-01-01

328

Performance of hydrophobic interaction ligands for human membrane-bound catechol-O-methyltransferase purification.  

PubMed

Despite of membrane catechol-O-methyltransferase (MBCOMT, EC 2.1.1.6) physiological importance on catecholamines' O-methylation, no studies allowed their total isolation. Therefore, for the first time, we compare the performance of three hydrophobic adsorbents (butyl-, epoxy-, and octyl-Sepharose) in purification of recombinant human COMT (hMBCOMT) from crude Brevibacillus choshinensis cell lysates to develop a sustainable chromatographic process. Hydrophobic matrices were evaluated in terms of selectivity and hMBCOMT's binding and elution conditions. Results show that hMBCOMT's adsorption was promoted on octyl and butyl at ?375 mM NaH2 PO4, while on epoxy higher concentrations (>850 mM) were required. Additionally, hMBCOMT's elution was promoted on epoxy, butyl, and octyl using respectively 0.1-0.5, 0.25-1, and 1% of Triton X-100. On butyl media, a stepwise strategy using 375 and 0 mM NaH2PO4, followed by three elution steps at 0.25, 0.7 and 1% Triton X-100, allowed selective hMBCOMT isolation. In conclusion, significant amounts of MBCOMT were purified with high selectivity on a single chromatography procedure, despite its elution occurs on multiple peaks. Although successful applications of hydrophobic interaction chromatography in purification of membrane proteins are uncommon, we proved that traditional hydrophobic matrices can open a promising unexplored field to fulfill specific requirements for kinetic and pharmacological trials. PMID:23495043

Santos, Fátima Milhano; Pedro, Augusto Quaresma; Soares, Rui Filipe; Martins, Rita; Bonifácio, Maria Joăo; Queiroz, Joăo António; Passarinha, Luís António

2013-06-01

329

Study of the catechol-o-methyltransferase (COMT) gene with high aggression in children.  

PubMed

The etiology of childhood-onset aggression (COA) is poorly understood, but early COA can be considered as a strong risk factor for adult delinquency and criminal behavior. Callous-unemotional (CU) traits have been proposed as a developmental model of antisocial behavior. Catechol O-methyltransferase (COMT) has been associated with aggression, attention deficit/hyperactivity disorder (ADHD), and other psychiatric disorders. We report an association study between COMT single-nucleotide polymorphisms (SNPs), childhood aggression, and the CU trait in our sample of 144 children with scores at or exceeding the 90th percentile on the aggression subscale of the parent-reported Child Behavior Checklist and the Teacher's Report Form. The genotype analysis of rs6269 showed nominally significant association (P = .019) and rs4818 showed a trend (P = .064) with COA. Trends were observed for rs6269 and rs4818 with CU scores (P < .10) as well. The analyses stratified by ADHD, or gender showed no significant results. This is the first report to our knowledge evaluating COMT SNPs with the phenotype of high aggression in children with a possible role for the COMT marker in CU traits. Given the importance of CU traits in antisocial behavior, further investigation of COMT is warranted. PMID:22972758

Hirata, Yuko; Zai, Clement C; Nowrouzi, Behdin; Beitchman, Joseph H; Kennedy, James L

2013-01-01

330

Catechol-O-methyltransferase Val 158 Met polymorphism and antisaccade eye movements in schizophrenia.  

PubMed

The catechol-O-methyltransferase (COMT) enzyme catabolizes dopamine. The val(158)met single nucleotide polymorphism (rs4680) in the COMT gene has received considerable attention as a candidate gene for schizophrenia as well as for frontally mediated cognitive functions. Antisaccade performance is a good measure of frontal lobe integrity. Deficits on the task are considered a trait marker for schizophrenia. The aim of this study was to investigate the association of COMT val(158)met polymorphism with antisaccade eye movements in schizophrenia patients and healthy controls. Schizophrenia patients (N = 105) and healthy controls (N = 95) underwent infrared oculographic assessment of antisaccades. Subjects were genotyped for COMT val(158)met and divided into 3 groups according to genotype (val/val, val/met, and met/met). Patients displayed significantly more reflexive errors, longer and more variable latency, and lower amplitude gain than controls (all P < 0.02). A greater number of val(158) alleles was associated with shorter (P = 0.045) and less variable (P = 0.028) antisaccade latency and, nonsignificantly, with lower reflexive error rate (P = 0.056). None of these variables showed a group-by-genotype interaction (P > 0.1). There were no significant associations of genotype with measures of amplitude gain or spatial error (P > 0.2). The results suggest that COMT val(158) carrier status is associated with better performance on the antisaccade task. Possible explanations of this finding are discussed. PMID:18562342

Haraldsson, Haraldur Magnus; Ettinger, Ulrich; Magnusdottir, Brynja B; Sigmundsson, Thordur; Sigurdsson, Engilbert; Ingason, Andres; Petursson, Hannes

2010-01-01

331

Catechol-O-Methyltransferase Val158Met Polymorphism and Antisaccade Eye Movements in Schizophrenia  

PubMed Central

The catechol-O-methyltransferase (COMT) enzyme catabolizes dopamine. The val158met single nucleotide polymorphism (rs4680) in the COMT gene has received considerable attention as a candidate gene for schizophrenia as well as for frontally mediated cognitive functions. Antisaccade performance is a good measure of frontal lobe integrity. Deficits on the task are considered a trait marker for schizophrenia. The aim of this study was to investigate the association of COMT val158met polymorphism with antisaccade eye movements in schizophrenia patients and healthy controls. Schizophrenia patients (N = 105) and healthy controls (N = 95) underwent infrared oculographic assessment of antisaccades. Subjects were genotyped for COMT val158met and divided into 3 groups according to genotype (val/val, val/met, and met/met). Patients displayed significantly more reflexive errors, longer and more variable latency, and lower amplitude gain than controls (all P < 0.02). A greater number of val158 alleles was associated with shorter (P = 0.045) and less variable (P = 0.028) antisaccade latency and, nonsignificantly, with lower reflexive error rate (P = 0.056). None of these variables showed a group-by-genotype interaction (P > 0.1). There were no significant associations of genotype with measures of amplitude gain or spatial error (P > 0.2). The results suggest that COMT val158 carrier status is associated with better performance on the antisaccade task. Possible explanations of this finding are discussed. PMID:18562342

Haraldsson, Haraldur Magnus; Ettinger, Ulrich; Magnusdottir, Brynja B.; Sigmundsson, Thordur; Sigurdsson, Engilbert; Ingason, Andres; Petursson, Hannes

2010-01-01

332

Synthesis, Characterization, and Preliminary Investigation of Cell Interaction of Magnetic Nanoparticles with Catechol-Containing Shells  

SciTech Connect

Superparamagnetic iron oxide cores were synthesized by co-precipitation of Fe(II) and Fe(III) salts and subsequently stabilized by coating with different catechols (levodopa, dopamine, hydrocaffeic acid, dopamine-containing carboxymethyl dextran) known to act as high-affinity, bidentate ligands for Fe(III). The prepared stable magnetic fluids were characterized with regard to their chemical composition (content of iron and shell material, Fe(II)/Fe(III) ratio) and their physical properties (size, surface charge, magnetic parameters). The nanoparticles showed no or only slight cytotoxic effects within 1 and 4 days of incubation with 3T3 fibroblast cells. Preliminary experiments were performed to study the interaction of the prepared nanoparticles with human MCF-7 breast cancer cells and leukocytes. An intense interaction of the MCF-7 cells with these particles was found whereas the leukocytes showed a lower tendency of interaction. Based on these finding, the novel magnetic nanoparticles possess the potential for use in depletion of tumor cells from peripheral blood.

Wagner, Kerstin; Seemann, Thomas; Wyrwa, Ralf; Schnabelrauch, Matthias [Biomaterials Department, INNOVENT e. V., Pruessingstrasse 27 B, D-07745 Jena (Germany); Clement, Joachim H. [Department of Internal Medicine II, University Hospital Jena, Erlanger Allee 101, D-07740 Jena (Germany); Mueller, Robert [Institute of Photonic Technology, Albert-Einstein-Strasse 9, D-07745 Jena (Germany); Nietzsche, Sandor [Center for Electron Microscopy, University Hospital Jena, Ziegelmuehlenweg 1, D-07743 Jena (Germany)

2010-12-02

333

Room-temperature phosphorescent discrimination of catechol from resorcinol and hydroquinone based on sodium tripolyphosphate capped Mn-doped ZnS quantum dots.  

PubMed

A room-temperature phosphorescence (RTP) strategy was developed for direct, additive-free discrimination of catechol from resorcinol and hydroquinone based on sodium tripolyphosphate capped Mn-doped ZnS quantum dots (STPP-Mn-ZnS QDs). The RTP response of STPP-Mn-ZnS QDs to the three isomers was pH-dependent, and the greatest difference in the RTP response to the isomers was observed at pH 8.0: catechol enhanced the RTP intensity of the QDs, while resorcinol and hydroquinone had little effect on the RTP intensity of the QDs. The enhanced RTP intensity of 1 ?M catechol was not affected by the coexistence of 30 ?M resorcinol and 50 ?M hydroquinone at pH 8.0. The detection limit of this RTP method was 53 nM catechol, and the precision was 3.2% (relative standard deviation) for five replicate detections of 1 ?M catechol. The discrimination mechanism was ascribed to the weak bonded ligand of STPP-Mn-ZnS QDs and the different interaction between the three isomers and STPP-Mn-ZnS QDs. The strong binding of catechol to Zn resulted in the extraction of Zn from the surface of STPP-Mn-ZnS QDs and the generation of holes that were trapped by Mn(2+) to form Mn(3+). Catechol also promoted the reduction of Mn(3+) into Mn(2+) excited state, thus ultimately inducing the enhanced RTP response of STPP-Mn-ZnS QDs. PMID:23270545

Wang, He-Fang; Wu, Ye-Yu; Yan, Xiu-Ping

2013-02-01

334

Cotton Effects in Plant Ferredoxin and Xanthine Oxidase  

Microsoft Academic Search

The position and magnitude of the optically active absorption bands in the non-haem iron proteins xanthine oxidase and spinach ferredoxin are found to be very similar. A study of the Cotton effects in these proteins suggests that xanthine oxidase contains four identical pairs of iron atoms while spinach ferredoxin contains only one pair.

K. Garbett; R. D. Gillard; P. F. KNOWLES; J. E. STANGROOM

1967-01-01

335

Kinetic properties of glycerophosphate oxidase isolated from dry baker's yeast  

Microsoft Academic Search

The glycerophosphate oxidase is a flavoprotein responsible for the catalysis of the oxidation of the glycerophosphate to dihydroxyacetone phosphate, through the reduction of the oxygen to hydrogen peroxide. The glycerophosphate oxidase from baker's yeast was specific for l-?-glycerol phosphate. It was estimated by monitoring the consumption of oxygen with an oxygraph. An increase of 32% in consumption of oxygen was

Luciana Amade Camargo; Maria Henriques Lourenço Ribeiro; Maristela de Freitas Sanches Peres; Edwil Aparecida de Lucca Gattás

2008-01-01

336

Effect of contraceptive steroids on monoamine oxidase activity  

PubMed Central

Cyclical variations in monoamine oxidase activity during the human menstrual cycle, specific to the endometrium and modified in women undergoing contraceptive steroid treatment, may reflect changes in hormonal environment. Treatment of rats with individual constituents of the contraceptive pill causes analogous changes: oestrogens inhibit and progestogens potentiate uterine monoamine oxidase activity. ImagesFig. 2Fig. 3

Southgate, Jennifer; Collins, G. G. S.; Pryse-Davies, J.; Sandler, M.

1969-01-01

337

Evolution of cytochrome oxidase, an enzyme older than atmospheric oxygen.  

PubMed Central

Cytochrome oxidase is a key enzyme in aerobic metabolism. All the recorded eubacterial (domain Bacteria) and archaebacterial (Archaea) sequences of subunits 1 and 2 of this protein complex have been used for a comprehensive evolutionary analysis. The phylogenetic trees reveal several processes of gene duplication. Some of these are ancient, having occurred in the common ancestor of Bacteria and Archaea, whereas others have occurred in specific lines of Bacteria. We show that eubacterial quinol oxidase was derived from cytochrome c oxidase in Gram-positive bacteria and that archaebacterial quinol oxidase has an independent origin. A considerable amount of evidence suggests that Proteobacteria (Purple bacteria) acquired quinol oxidase through a lateral gene transfer from Gram-positive bacteria. The prevalent hypothesis that aerobic metabolism arose several times in evolution after oxygenic photosynthesis, is not sustained by two aspects of the molecular data. First, cytochrome oxidase was present in the common ancestor of Archaea and Bacteria whereas oxygenic photosynthesis appeared in Bacteria. Second, an extant cytochrome oxidase in nitrogen-fixing bacteria shows that aerobic metabolism is possible in an environment with a very low level of oxygen, such as the root nodules of leguminous plants. Therefore, we propose that aerobic metabolism in organisms with cytochrome oxidase has a monophyletic and ancient origin, prior to the appearance of eubacterial oxygenic photosynthetic organisms. Images PMID:8013452

Castresana, J; Lubben, M; Saraste, M; Higgins, D G

1994-01-01

338

Brief Communications Brain Monoamine Oxidase A Activity Predicts Trait  

E-print Network

Brief Communications Brain Monoamine Oxidase A Activity Predicts Trait Aggression Nelly Alia of this behavior. A potential neu- rochemical target is monoamine oxidase A (MAO A), an enzyme involved in metabolism of monoamines in brain and other or- gans (Shih and Thompson, 1999). MAO A catalytic activity re

Goldstein, Rita

339

Interheme electron tunneling in cytochrome c oxidase  

PubMed Central

Cytochrome c oxidase (CcO) is the terminal enzyme of the respiratory chain that catalyzes respiratory reduction of dioxygen (O2) to water in all eukaryotes and many aerobic bacteria. CcO, and its homologs among the heme-copper oxidases, has an active site composed of an oxygen-binding heme and a copper center in the vicinity, plus another heme group that donates electrons to this site. In most oxidoreduction enzymes, electron transfer (eT) takes place by quantum-mechanical electron tunneling. Here we show by independent molecular dynamics and quantum-chemical methods that the heme-heme eT in CcO differs from the majority of cases in having an exceptionally low reorganization energy. We show that the rate of interheme eT in CcO may nevertheless be predicted by the Moser-Dutton equation if reinterpreted as the average of the eT rates between all individual atoms of the donor and acceptor weighed by the respective packing densities between them. We argue that this modification may be necessary at short donor/acceptor distances comparable to the donor/acceptor radii. PMID:21106766

Kaila, Ville R. I.; Johansson, Mikael P.; Sundholm, Dage; Wikstrom, Marten

2010-01-01

340

Bacterial xanthine oxidase from Arthrobacter S-2.  

PubMed Central

Arthrobacter S-2, originally isolated by enrichment on xanthine, produced high levels of xanthine oxidase activity, requiring as little as a 20-fold purification to approach homogeneity with some preparations. Molecular oxygen, ferricyanide, and 2,6-dichlorophenol-indophenol served as electron acceptors, but nicotinamide adenine dinucleotide did not. The enzyme was relatively specific when compared with previously studied xanthine-oxidizing enzymes, but at least one purine was observed to be oxidized at each of the three positions of the purine ring that have been subject to oxidation by this type of enzyme. The enzyme had a relatively high Km for xanthine (1.3 X 10(-4) M), and substrate inhibition was not observed with this compound, in contrast to the enzyme from cow's milk. In fact, an opposite effect was observed, and double-reciprocal plots with xanthine as the variable substrate showed a concave downward deviation at high concentrations. At 2.5 mM xanthine the enzyme had a specific activity approximately 50 times that of the most active preparations of the milk enzyme. The spectrum of the Arthrobacter enzyme resembled that of milk xanthine oxidase, suggesting a similarity of the prosthetic centers of the two enzymes. The bacterial enzyme was relatively small and may be dimeric, with approximate native and subunit molecular weights of 146,000 and 79,000, respectively. PMID:681279

Woolfolk, C A; Downard, J S

1978-01-01

341

Cytochrome c Oxidase Dysfunction in Oxidative Stress  

PubMed Central

Cytochrome c Oxidase (CcO) is the terminal oxidase of the mitochondrial electron transport chain. This bigenomic enzyme in mammals contains 13 subunits, of which, three catalytic subunits are encoded by the mitochondrial genes. The remaining ten subunits with suspected roles in the regulation, and/or, assembly are coded by the nuclear genome. The enzyme contains two heme groups (heme a and a3) and two Cu2+ centers (Cu2+ A and Cu2+ B) as catalytic centers and handles more than 90% of molecular O2 respired by the mammalian cells and tissues. CcO is a highly regulated enzyme which is believed to be the pace setter for mitochondrial oxidative metabolism and ATP synthesis. The structure and function of the enzyme is affected in a wide variety of diseases including cancer, neurodegenerative diseases, myocardial ischemia/reperfusion, bone and skeletal diseases and diabetes. Despite handling a high O2 load the role of CcO in the production of reactive oxygen species still remains a subject of debate. However, a volume of evidence suggests that CcO dysfunction is invariably associated with increased mitochondrial reactive oxygen species production and cellular toxicity. In this article we review literature on mechanisms of multimodal regulation of CcO activity by a wide spectrum of physiological and pathological factors. We also review an array of literature on the direct or indirect roles of CcO in reactive oxygen species production. PMID:22841758

Srinivasan, Satish; Avadhani, Narayan G.

2012-01-01

342

The complex roles of NADPH oxidases in fungal infection.  

PubMed

NADPH oxidases play key roles in immunity and inflammation that go beyond the production of microbicidal reactive oxygen species (ROS). The past decade has brought a new appreciation for the diversity of roles played by ROS in signalling associated with inflammation and immunity. NADPH oxidase activity affects disease outcome during infections by human pathogenic fungi, an important group of emerging and opportunistic pathogens that includes Candida, Aspergillus and Cryptococcus species. Here we review how alternative roles of NADPH oxidase activity impact fungal infection and how ROS signalling affects fungal physiology. Particular attention is paid to roles for NADPH oxidase in immune migration, immunoregulation in pulmonary infection, neutrophil extracellular trap formation, autophagy and inflammasome activity. These recent advances highlight the power and versatility of spatiotemporally controlled redox regulation in the context of infection, and point to a need to understand the molecular consequences of NADPH oxidase activity in the cell. PMID:24905433

Hogan, Deborah; Wheeler, Robert T

2014-08-01

343

Ascorbic acid and L-gulonolactone oxidase in lagomorphs.  

PubMed

1. The activity of L-gulonolactone oxidase (EC 1.1.3.8) in the liver of eastern cottontail rabbits (Sylvilagus floridanus) is about 10-fold greater in winter than in summer. 2. L-gulonolactone oxidase activity is low and tissue ascorbate high during all seasons in snowshoe hares (Lepus americanus). 3. Liver contents of ascorbate fall to low levels in L. americanus fed on rabbit chow in the laboratory. 4. The activity of L-gulonolactone oxidase in liver of Sylvilagus and Oryctolagus is depressed by feeding high levels of L-ascorbic acid. 5. The New Zealand White breed of domestic rabbit (Oryctolagus cuniculus) has considerably higher levels of L-gulonolactone oxidase and liver ascorbate than does the Dutch breed. 6. In a wild population of Oryctolagus sampled in Australia L-gulonolactone oxidase levels were intermediate between those of the two domestic breeds and more variable than either. PMID:318384

Jenness, R; Birney, E C; Ayaz, K L

1978-01-01

344

Extraction and Application of Laccases from Shimeji Mushrooms (Pleurotus ostreatus) Residues in Decolourisation of Reactive Dyes and a Comparative Study Using Commercial Laccase from Aspergillus oryzae.  

PubMed

Oxidases are able to degrade organic pollutants; however, high costs associated with biocatalysts production still hinder their use in environmental biocatalysis. Our study compared the action of a commercial laccase from Aspergillus oryzae and a rich extract from Pleurotus ostreatus cultivation residues in decolourisation of reactive dyes: Drimaren Blue X-3LR (DMBLR), Drimaren Blue X-BLN (DMBBLN), Drimaren Rubinol X-3LR (DMR), and Drimaren Blue C-R (RBBR). The colour removal was evaluated by considering dye concentration, reaction time, absence or presence of the mediator ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), and the source of laccase. The presence of ABTS was essential for decolourisation of DMR (80-90%, 1?h) and RBBR (80-90%, 24?h) with both laccases. The use of ABTS was not necessary in reactions containing DMBLR (85-97%, 1?h) and DMBBLN (63-84%, 24?h). The decolourisation of DMBBLN by commercial laccase showed levels near 60% while the crude extract presented 80% in 24?h. PMID:21052547

Teixeira, Ricardo Sposina S; Pereira, Patrícia Maia; Ferreira-Leităo, Viridiana S

2010-01-01

345

Extraction and Application of Laccases from Shimeji Mushrooms (Pleurotus ostreatus) Residues in Decolourisation of Reactive Dyes and a Comparative Study Using Commercial Laccase from Aspergillus oryzae  

PubMed Central

Oxidases are able to degrade organic pollutants; however, high costs associated with biocatalysts production still hinder their use in environmental biocatalysis. Our study compared the action of a commercial laccase from Aspergillus oryzae and a rich extract from Pleurotus ostreatus cultivation residues in decolourisation of reactive dyes: Drimaren Blue X-3LR (DMBLR), Drimaren Blue X-BLN (DMBBLN), Drimaren Rubinol X-3LR (DMR), and Drimaren Blue C-R (RBBR). The colour removal was evaluated by considering dye concentration, reaction time, absence or presence of the mediator ABTS (2,2?-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), and the source of laccase. The presence of ABTS was essential for decolourisation of DMR (80–90%, 1?h) and RBBR (80–90%, 24?h) with both laccases. The use of ABTS was not necessary in reactions containing DMBLR (85–97%, 1?h) and DMBBLN (63–84%, 24?h). The decolourisation of DMBBLN by commercial laccase showed levels near 60% while the crude extract presented 80% in 24?h. PMID:21052547

Teixeira, Ricardo Sposina S.; Pereira, Patricia Maia; Ferreira-Leitao, Viridiana S.

2010-01-01

346

The human lysyl oxidase-like 2 protein functions as an amine oxidase toward collagen and elastin.  

PubMed

The lysyl oxidase-like 2 (LOXL2) protein is a human paralogue of lysyl oxidase (LOX) that functions as an amine oxidase for formation of lysine-derived cross-links found in collagen and elastin. In addition to the C-terminal domains characteristic to the LOX family members, LOXL2 contains four scavenger receptor cysteine-rich (SRCR) domains in the N-terminus. In order to assess the amine oxidase activity of LOXL2, we expressed a series of recombinant LOXL2 proteins with deletions in the SRCR domains, using an Escherichia coli expression system. All of the purified recombinant LOXL2 proteins, with or without the SRCR domains in the N-terminus, showed significant amine oxidase activity toward several different types of collagen and elastin in in vitro amine oxidase assays, indicating deletion of the SRCR domains does not interfere with amine oxidase activity of LOXL2. Further, amine oxidase activity of LOXL2 was not susceptible to inhibition by ?-aminopropionitrile, an irreversible inhibitor of LOX, suggesting a different enzymatic mechanism between these two paralogues. PMID:20306300

Kim, Young-Mi; Kim, Eun-Cheol; Kim, Youngho

2011-01-01

347

Deletion of creB in Aspergillus oryzae Increases Secreted Hydrolytic Enzyme Activity  

PubMed Central

Aspergillus oryzae has been used in the food and beverage industry for centuries, and industrial strains have been produced by multiple rounds of selection. Targeted gene deletion technology is particularly useful for strain improvement in such strains, particularly when they do not have a well-characterized meiotic cycle. Phenotypes of an Aspergillus nidulans strain null for the CreB deubiquitinating enzyme include effects on growth and repression, including increased activity levels of various enzymes. We show that Aspergillus oryzae contains a functional homologue of the CreB deubiquitinating enzyme and that a null strain shows increased activity levels of industrially important secreted enzymes, including cellulases, xylanases, amylases, and proteases, as well as alleviated inhibition of spore germination on glucose medium. Reverse transcription-quantitative PCR (RT-qPCR) analysis showed that the increased levels of enzyme activity in both Aspergillus nidulans and Aspergillus oryzae are mirrored at the transcript level, indicating transcriptional regulation. We report that Aspergillus oryzae DAR3699, originally isolated from soy fermentation, has a similar phenotype to that of a creB deletion mutant of the RIB40 strain, and it contains a mutation in the creB gene. Collectively, the results for Aspergillus oryzae, Aspergillus nidulans, Trichoderma reesei, and Penicillium decumbens show that deletion of creB may be broadly useful in diverse fungi for increasing production of a variety of enzymes. PMID:23835170

Hunter, A. J.; Morris, T. A.; Jin, B.; Saint, C. P.

2013-01-01

348

Mitochondrial Respiratory Pathways Inhibition in Rhizopus oryzae Potentiates Activity of Posaconazole and Itraconazole via Apoptosis  

PubMed Central

The incidence of mucormycosis has increased drastically in immunocompromised patients. Also the array of targets whose inhibition results in Mucorales death is limited. Recently, researchers identified mitochondria as important regulators of detoxification and virulence mechanisms in fungi. In this context, targeting the mitochondrial respiratory chain may provide a new platform for antifungal development. We hypothesized that targeting respiratory pathways potentiates triazoles activity via apoptosis. We found that simultaneous administration of antimycin A (AA) and benzohydroxamate (BHAM), inhibitors of classical and alternative mitochondrial pathways respectively, resulted in potent activity of posaconazole (PCZ) and itraconazole (ICZ) against Rhizopus oryzae. We observed cellular changes characteristic of apoptosis in R. oryzae cells treated with PCZ or ICZ in combination with AA and BHAM. The fungicidal activity of this combination against R. oryzae was correlated with intracellular reactive oxygen species accumulation (ROS), phosphatidylserine externalization, mitochondrial membrane depolarization, and increased caspase like activity. DNA fragmentation and condensation assays also revealed apoptosis of R. oryzae cells. These apoptotic features were prevented by the addition of the ROS scavenger N-acetyl-cysteine. Taken together, these findings suggest that the use of PCZ or ICZ in combination with AA and BHAM makes R. oryzae exquisitely sensitive to treatment with triazoles via apoptosis. This strategy may serve as a new model for the development of improved or novel antifungal agents. PMID:23696824

Shirazi, Fazal; Kontoyiannis, Dimitrios P.

2013-01-01

349

Pentachlorophenol sorption in nylon fiber and removal by immobilized Rhizopus oryzae ENHE.  

PubMed

This study describes pentachlophenol (PCP) sorption in nylon fiber in which Rhizopus oryzae ENHE was immobilized to remove the chemical compound. The experimental sorption data were analyzed using the Langmuir, Freundlich, and Redlich-Peterson isotherm models using non-linear error functions to fit the experimental data to the three models. Results showed that the isotherm obtained from the data fitted the three models used. However, the g parameter from Redlich-Peterson model showed that the isotherm obtained approaches the Freundlich model. This support reached the sorption equilibrium concentration at 3mg PCPg(-1)nylon. To study PCP removal capability by R. oryzae ENHE and to eliminate the error caused by PCP sorbed by the nylon fiber during its quantification, nylon fiber at PCP equilibrium sorption concentration was used to immobilize R. oryzae ENHE. It was found that this fungus grew within nylon fiber cubes in presence or not of PCP, even when PCP caused growth inhibition. Maximum biomass accumulated into nylon cubes without PCP was of 32 mg biomass g(-1)nylon and into nylon cubes at PCP equilibrium concentration was of 18 mg g(-1)nylon. The results showed that R. oryzae ENHE immobilized into nylon fiber removed 88.6% and 92% of PCP in cultures with 12.5 and 25 mg PCPL(-1), as initial concentration, respectively. This is the first work to report that a zygomycete, such as R. oryzae ENHE, immobilized into nylon fiber kept its potential to remove PCP. PMID:21514996

León-Santiestebán, Hugo; Meraz, Mónica; Wrobel, Kazimierz; Tomasini, Araceli

2011-06-15

350

Non-host resistance to penetration and hyphal growth of Magnaporthe oryzae in Arabidopsis.  

PubMed

Rice blast caused by Magnaporthe oryzae is a devastating disease of rice. Mechanisms of rice resistance to blast have been studied extensively, and the rice-M. oryzae pathosystem has become a model for plant-microbe interaction studies. However, the mechanisms of non-host resistance (NHR) to rice blast in other plants remain poorly understood. We found that penetration resistance to M. oryzae in multiple mutants, including pen2 NahG pmr5 agb1 and pen2 NahG pmr5 mlo2 plants, was severely compromised and that fungal growth was permitted in penetrated epidermal cells. Furthermore, rice Pi21 enhanced movement of infection hyphae from penetrated Arabidopsis epidermal cells to adjacent mesophyll cells. These results indicate that PEN2, PMR5, AGB1, and MLO2 function in both penetration and post-penetration resistance to M. oryzae in Arabidopsis, and suggest that the absence of rice Pi21 contributed to Arabidopsis NHR to M. oryzae. PMID:22355686

Nakao, Misato; Nakamura, Ryotaro; Kita, Kaori; Inukai, Ryuya; Ishikawa, Atsushi

2011-01-01

351

An evaluation of aflatoxin and cyclopiazonic acid production in Aspergillus oryzae.  

PubMed

To date, edible fungi such as Aspergillus flavus var. oryzae (A. oryzae) has been considered as safe. However, some strains can produce mycotoxins. Thus, the biosynthetic ability to produce mycotoxins should be reevaluated to determine the safety of edible fungi. We analyzed the production of aflatoxins and cyclopiazonic acid (CPA) from edible fungi such as A. oryzae isolated from various Korean foods using multiplex PCR, enzyme-linked immunosorbent assay, and high-performance liquid chromatography (HPLC). In the multiplex PCR analysis of aflatoxin biosynthetic genes omtB, aflR, ver-1, and omtA, 5 of 19 Aspergillus strains produced all PCR products. Among them, aflatoxin B1 and aflatoxin B2 were detected from only A. flavus KACC 41403 by HPLC. Aflatoxins were not detected from the other four strains that produced all positive PCR bands. Aflatoxin also was not detected from 12 strains that had PCR patterns without aflR or ver-1 and from 2 strains that did not produce any of the expected PCR products. Only the seven A. oryzae strains that produced all of the positive PCR bands including the CPA biosynthetic genes maoA, dmaT, and pks-nrps produced CPA. CPA and aflatoxin production must be evaluated before A. oryzae strains are used for the development of fermented foods. PMID:24853527

Kim, Nam Yeun; Lee, Jin Hee; Lee, Inhyung; Ji, Geun Eog

2014-06-01

352

Differentiation in MALDI-TOF MS and FTIR spectra between two pathovars of Xanthomonas oryzae.  

PubMed

Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc) strains are closely related phenotypically and genetically, which make it difficult to differentiate between the two pathovars based on phenotypic and DNA-based methods. In this study, a fast and accurate method was developed based on the differences in MALDI-TOF MS and FTIR spectra between the two pathovars. MALDI-TOF MS analysis revealed that 9 and 10 peaks are specific to Xoo and Xoc, respectively, which can be used as biomarkers to identify and differentiate the two closely related pathovars. Furthermore, FTIR analysis showed that there is a significant difference in both the band frequencies and absorption intensity of various functional groups between the two pathovars. In particular, the 6 peaks at 3433, 2867, 1273, 1065, 983 and 951cm(-1) were specific to the Xoo strains, while one peak at 1572cm(-1) was specific to the Xoc strains. Overall, this study gives the first attempt to identify and differentiate the two pathovars of X. oryzae based on mass and FTIR spectra, which will be helpful for the early detection and prevention of the two rice diseases caused by both X. oryzae pathovars. PMID:24996215

Ge, Mengyu; Li, Bin; Wang, Li; Tao, Zhongyun; Mao, Shengfeng; Wang, Yangli; Xie, Guanlin; Sun, Guochang

2014-12-10

353

Perchlorate reduction using free and encapsulated Azospira oryzae enzymes.  

PubMed

Existing methods for perchlorate remediation are hampered by the common co-occurrence of nitrate, which is structurally similar and a preferred electron acceptor. In this work, the potential for perchlorate removal using cell-free bacterial enzymes as biocatalysts was investigated using crude cell lysates and soluble protein fractions of Azospira oryzae PS, as well as soluble protein fractions encapsulated in lipid and polymer vesicles. The crude lysates showed activities between 41?700 to 54?400 U L(-1) (2.49 to 3.06 U mg(-1) total protein). Soluble protein fractions had activities of 15?400 to 29?900 U L(-1) (1.70 to 1.97 U mg(-1)) and still retained an average of 58.2% of their original activity after 23 days of storage at 4 °C under aerobic conditions. Perchlorate was removed by the soluble protein fraction at higher rates than nitrate. Importantly, perchlorate reduction occurred even in the presence of 500-fold excess nitrate. The soluble protein fraction retained its function after encapsulation in lipid or polymer vesicles, with activities of 13.8 to 70.7 U L(-1), in agreement with theoretical calculations accounting for the volume limitation of the vesicles. Further, encapsulation mitigated enzyme inactivation by proteinase K. Enzyme-based technologies could prove effective at perchlorate removal from water cocontaminated with nitrate or sulfate. PMID:23924304

Hutchison, Justin M; Poust, Sean K; Kumar, Manish; Cropek, Donald M; Macallister, Irene E; Arnett, Clint M; Zilles, Julie L

2013-09-01

354

``Additive'' cooperativity of hydrogen bonds in complexes of catechol with proton acceptors in the gas phase: FTIR spectroscopy and quantum chemical calculations  

NASA Astrophysics Data System (ADS)

Experimental study of hydrogen bond cooperativity in hetero-complexes in the gas phase was carried out by IR-spectroscopy method. Stretching vibration frequencies of Osbnd H groups in phenol and catechol molecules as well as of their complexes with nitriles and ethers were determined in the gas phase using a specially designed cell. Osbnd H groups experimental frequency shifts in the complexes of catechol induced by the formation of intermolecular hydrogen bonds are significantly higher than in the complexes of phenol due to the hydrogen bond cooperativity. It was shown that the cooperativity factors of hydrogen bonds in the complexes of catechol with nitriles and ethers in the gas phase are approximately the same. Quantum chemical calculations of the studied systems have been performed using density functional theory (DFT) methods. It was shown, that theoretically obtained cooperativity factors of hydrogen bonds in the complexes of catechol with proton acceptors are in good agreement with experimental values. Cooperative effects lead to a strengthening of intermolecular hydrogen bonds in the complexes of catechol on about 30%, despite the significant difference in the proton acceptor ability of the bases. The analysis within quantum theory of atoms in molecules was carried out for the explanation of this fact.

Varfolomeev, Mikhail A.; Klimovitskii, Alexander E.; Abaidullina, Dilyara I.; Madzhidov, Timur I.; Solomonov, Boris N.

2012-06-01

355

EFECTO DE LA COBERTURA DE RASTROJOS EN LA GERMINACIÓN DEL ARROZ (Oryza sativa L.) Y PRINCIPALES MALEZAS ASOCIADAS 1  

Microsoft Academic Search

Crop residues effect on the germination of rice (Oryza sativa L.) and its major weeds. Three simultaneous experiments were conducted in El Pelón de la Bajura Farm, Guanacaste, Costa Rica in 2003 to determine the degree of interference caused by varying amounts of previous rice crop (Oryza sativa L.) residue on the emergence of rice and associated weeds. Nine coverage

Yemel M. Ortega; Renán Agüero Alvarado

2005-01-01

356

EFECTOS DE DOS SISTEMAS DE LABRANZA SOBRE POBLACIONES DE ARROZ ROJO (Oryza sativa L.) EN UN AGROECOSISTEMA ARROCERO INUNDADO1  

Microsoft Academic Search

Effects of two tillage systems on red rice (Oryza sativa L.) populations in a flooded rice agroecosystem. The influence of two tillage systems was evaluated on red rice (Oryza sativa L.) populations and other frequent weeds in rice agroecosystems throughout four consecutive cycles of commercial flooded rice. In order to estimate the seed bank size, soil samples from three depths

Yemel M. Ortega; Renán Agüero Alvarado

2005-01-01

357

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

PubMed Central

Autonomic dysfunction is frequent in patients with fibromyalgia (FM). Heart rate variability analyses have demonstrated signs of ongoing sympathetic hyperactivity. Catecholamines are sympathetic neurotransmitters. Catechol-O-methyltransferase (COMT), an enzyme, is the major catecholamine-clearing pathway. There are several single-nucleotide polymorphisms (SNPs) in the COMT gene associated with the different catecholamine-clearing abilities of the COMT enzyme. These SNPs are in linkage disequilibrium and segregate as 'haplotypes'. Healthy females with a particular COMT gene haplotype (ACCG) producing a defective enzyme are more sensitive to painful stimuli. The objective of our study was to define whether women with FM, from two different countries (Mexico and Spain), have the COMT gene haplotypes that have been previously associated with greater sensitivity to pain. All the individuals in the study were female. Fifty-seven Mexican patients and 78 Spanish patients were compared with their respective healthy control groups. All participants filled out the Fibromyalgia Impact Questionnaire (FIQ). Six COMT SNPs (rs2097903, rs6269, rs4633, rs4818, rs4680, and rs165599) were genotyped from peripheral blood DNA. In Spanish patients, there was a significant association between three SNPs (rs6269, rs4818, and rs4680) and the presence of FM when compared with healthy controls. Moreover, in Spanish patients with the 'high pain sensitivity' haplotype (ACCG), the disease, as assessed by the FIQ, was more severe. By contrast, Mexican patients displayed only a weak association between rs6269 and rs165599, and some FIQ subscales. In our group of Spanish patients, there was an association between FM and the COMT haplotype previously associated with high pain sensitivity. This association was not observed in Mexican patients. Studies with a larger sample size are needed in order to verify or amend these preliminary results. PMID:17961261

Vargas-Alarcon, Gilberto; Fragoso, Jose-Manuel; Cruz-Robles, David; Vargas, Angelica; Vargas, Alfonso; Lao-Villadoniga, Jose-Ignacio; Garcia-Fructuoso, Ferran; Ramos-Kuri, Manuel; Hernandez, Fernando; Springall, Rashidi; Bojalil, Rafael; Vallejo, Maite; Martinez-Lavin, Manuel

2007-01-01

358

How Metal Substitution Affects the Enzymatic Activity of Catechol-O-Methyltransferase  

PubMed Central

Catechol-O-methyltransferase (COMT) degrades catecholamines, such as dopamine and epinephrine, by methylating them in the presence of a divalent metal cation (usually Mg(II)), and S-adenosyl-L-methionine. The enzymatic activity of COMT is known to be vitally dependent on the nature of the bound metal: replacement of Mg(II) with Ca(II) leads to a complete deactivation of COMT; Fe(II) is slightly less than potent Mg(II), and Fe(III) is again an inhibitor. Considering the fairly modest role that the metal plays in the catalyzed reaction, this dependence is puzzling, and to date remains an enigma. Using a quantum mechanical / molecular mechanical dynamics method for extensive sampling of protein structure, and first principle quantum mechanical calculations for the subsequent mechanistic study, we explicate the effect of metal substitution on the rate determining step in the catalytic cycle of COMT, the methyl transfer. In full accord with experimental data, Mg(II) bound to COMT is the most potent of the studied cations and it is closely followed by Fe(II), whereas Fe(III) is unable to promote catalysis. In the case of Ca(II), a repacking of the protein binding site is observed, leading to a significant increase in the activation barrier and higher energy of reaction. Importantly, the origin of the effect of metal substitution is different for different metals: for Fe(III) it is the electronic effect, whereas in the case of Ca(II) it is instead the effect of suboptimal protein structure. PMID:23056605

Sparta, Manuel; Alexandrova, Anastassia N.

2012-01-01

359

Catechol-O-methyltransferase gene methylation and substance use in adolescents: the TRAILS study.  

PubMed

Substance use often starts in adolescence and poses a major problem for society and individual health. The dopamine system plays a role in substance use, and catechol-O-methyltransferase (COMT) is an important enzyme that degrades dopamine. The Val(108/158) Met polymorphism modulates COMT activity and thus dopamine levels, and has been linked to substance use. COMT gene methylation, on the other hand, may affect expression and thus indirectly COMT activity. We investigated whether methylation of the COMT gene was associated with adolescents' substance use. Furthermore, we explored whether the COMT Val(108/158) Met polymorphism interacts with COMT gene methylation in association with substance use. In 463 adolescents (mean age=16, 50.8% girls), substance use (cigarette smoking, alcohol and cannabis use) was assessed with self-report questionnaires. From blood samples, COMT Val(108/158) Met genotype and methylation rates of membrane bound (MB) and soluble (S) COMT promoters were assessed. MB-COMT promoter methylation was associated with non-daily smoking [odds ratio (OR)=1.82, P=0.03], but not with daily smoking (OR=1.20, P=0.34), MB-COMT promoter methylation was not associated with alcohol use. Adolescents with the Met/Met genotype and high rates of MB-COMT promoter methylation were less likely to be high-frequent cannabis users than adolescents with the Val/Val or Val/Met genotype. S-COMT promoter methylation was not associated with substance use. These results indicate that there is an association between substance use and COMT gene methylation. Although this association is complex, combining genetic and epigenetic variation of the COMT gene may be helpful in further elucidating the influence of the dopamine system on substance use in adolescence. PMID:24902721

van der Knaap, L J; Schaefer, J M; Franken, I H A; Verhulst, F C; van Oort, F V A; Riese, H

2014-09-01

360

Catechol-O-methyltransferase gene variation: impact on amygdala response to aversive stimuli.  

PubMed

The functional catechol-O-methyltransferase (COMT) val158met polymorphism has been found to be associated with anxiety disorders and depression as well as with neural correlates of emotional processing, with, however, contradictory results. Thus, the aim of the present study was to re-evaluate the impact of the COMT val158met variant on neural activation correlates of emotional face processing in a sample of healthy probands. In 85 healthy subjects genotyped for the COMT val158met polymorphism, amygdala responses were assessed by means of fMRI. Participants were presented with anger- and fear-relevant faces in a robust emotion-processing paradigm. For exploratory reasons, a supplementary whole-brain analysis of the allele-dose model and a gender-stratified analysis were conducted. The COMT 158val allele showed an allele-dose effect on increased predominantly left-sided amygdala activity in response to fearful/angry facial stimuli (p(uncorrected)=.00004). This effect was independent from the distribution of the frequently studied 5-HTTLPR polymorphism for which a linear effect of S-alleles on amygdala responsiveness was replicated. The influence of COMT 158val alleles was only discerned in the female subgroup of probands. The whole-brain analysis suggested associations of the COMT 158val allele with increased activity in areas of the ventral visual stream and the lateral prefrontal cortex. The present results provide further support for a-potentially female-specific-role of the COMT val158met polymorphism in the genetic and neural underpinnings of anxiety- and depression-related intermediate phenotypes and may aid in further clarifying the differential role of COMT genotype driven dopaminergic tonus in the processing of emotionally salient stimuli. PMID:22387174

Domschke, Katharina; Baune, Bernhard T; Havlik, Linda; Stuhrmann, Anja; Suslow, Thomas; Kugel, Harald; Zwanzger, Peter; Grotegerd, Dominik; Sehlmeyer, Christina; Arolt, Volker; Dannlowski, Udo

2012-05-01

361

Effects of Catechol-O-Methyltransferase on Normal Variation in the Cognitive Function of Children  

PubMed Central

Objective Genetic variants that contribute to the risk of psychiatric disorders may also affect normal variation in psychological function. Indeed, the behavioral effects of many genetic variants may be better understood as process-specific rather than disease-specific. A functional valine-to-methionine (Val158Met) polymorphism in the catechol-O-methyltransferase (COMT) gene has been associated with cognitive function and brain metabolic activity accompanying such tasks. Not all studies are consistent, and less is known about the effect of this polymorphism during development. The authors tested the hypothesis that a more informative COMT haplotype predicts normal cognitive development in a large population-based cohort of children enrolled in the Avon Longitudinal Study of Parents and children. Method Effects on verbal and performance IQ as well as verbal inhibition were assessed at age 8, and effects onworking memory were assessed at age 10. From the five COMT single nucleotide polymorphisms (SNPs) genotyped, the effect of a functional three-SNP haplotype consisting of Val158Met and two synonymous SNPs (rs6269 and rs4818), which together exert a major influence on the level of COMT expression and enzyme activity, was evaluated. Results This three-SNP haplotype predicted both verbal inhibition and working memory, and there was a genotype-by-sex interaction on verbal IQ. The effect of COMT genotype (diplotype) on cognition was curvilinear, which is consistent with the “inverted U” model of dopamine effect on frontal cortical efficiency. In addition, the SNP rs2075507 (previously rs2097603) was independently associatedwith verbal inhibition, while rs165599 showed no main cognitive effects. However, rs165599 showed a genotype-by-sex interaction with working memory. Conclusions Genetic variation at several loci in the COMT gene affects normal cognitive function in children. PMID:19605537

Barnett, Jennifer H.; Heron, Jon; Goldman, David; Jones, Peter B.; Xu, Ke

2009-01-01

362

How metal substitution affects the enzymatic activity of catechol-o-methyltransferase.  

PubMed

Catechol-O-methyltransferase (COMT) degrades catecholamines, such as dopamine and epinephrine, by methylating them in the presence of a divalent metal cation (usually Mg(II)), and S-adenosyl-L-methionine. The enzymatic activity of COMT is known to be vitally dependent on the nature of the bound metal: replacement of Mg(II) with Ca(II) leads to a complete deactivation of COMT; Fe(II) is slightly less than potent Mg(II), and Fe(III) is again an inhibitor. Considering the fairly modest role that the metal plays in the catalyzed reaction, this dependence is puzzling, and to date remains an enigma. Using a quantum mechanical / molecular mechanical dynamics method for extensive sampling of protein structure, and first principle quantum mechanical calculations for the subsequent mechanistic study, we explicate the effect of metal substitution on the rate determining step in the catalytic cycle of COMT, the methyl transfer. In full accord with experimental data, Mg(II) bound to COMT is the most potent of the studied cations and it is closely followed by Fe(II), whereas Fe(III) is unable to promote catalysis. In the case of Ca(II), a repacking of the protein binding site is observed, leading to a significant increase in the activation barrier and higher energy of reaction. Importantly, the origin of the effect of metal substitution is different for different metals: for Fe(III) it is the electronic effect, whereas in the case of Ca(II) it is instead the effect of suboptimal protein structure. PMID:23056605

Sparta, Manuel; Alexandrova, Anastassia N

2012-01-01

363

Survey of Oxidase-Positive and Negative Bacteria Using a Quantitative Kovacs Oxidase Test  

Microsoft Academic Search

A manometric assay system employing ascorbate and N,N,N',N'-tetra- methyl-p-phenylenediamine (TMPD) was used to quantitate terminal oxidase activity in bacterial non-proliferating whole cells. A wide variety of physiologi- cally diverse bacteria, all of which were grown heterotrophically, was tested by this assay. For this survey study, 79 bacterial strains, which represented 34 genera, were used. Turbidimetrically standardized resting (non-proliferat- ing) cell

PETER JURTSHUK; DONALD N. McQUITTY

364

Dephenolization of industrial wastewaters catalyzed by polyphenol oxidase  

SciTech Connect

A new enzymatic method for the removal of phenols from industrial aqueous effluents has been developed. The method uses the enzyme polyphenol oxidase which oxidizes phenols to the corresponding o-quinones; the latter then undergo a nonenzymatic polymerization to form water-insoluble aggregates. Therefore, the enzyme in effect precipitates phenols from water. Polyphenol oxidase has been found to nearly completely dephenolize solutions of phenol in the concentration range from 0.01 to 1.0 g/L. The enzymatic treatment is effective over a wide range of pH and temperature; a crude preparation of polyphenol oxidase (mushroom extract) is as effective as a purified, commercially obtained version. In addition to phenol itself, polyphenol oxidase is capable of precipitating from water a number of substituted phenols (cresols, chlorophenols, naphthol, etc.). Also, even pollutants which are unreactive towards polyphenol oxidase can be enzymatically coprecipitated with phenol. The polyphenol oxidase treatment has been successfully used to dephenolize two different real industrial wastewater samples, from a plant producing triarylphosphates and from a coke plant. The advantage of the polyphenol oxidase dephenolization over the peroxidase-catalyzed one previously elaborated by the authors is that the former enzyme uses molecular oxygen instead of costly hydrogen peroxide (used by peroxidase) as an oxidant.

Atlow, S.C.; Bonadonna-Aparo, L.; Klibanov, A.M.

1984-01-01

365

Evaluation of oxalate decarboxylase and oxalate oxidase for industrial applications.  

PubMed

Increased recirculation of process water has given rise to problems with formation of calcium oxalate incrusts (scaling) in the pulp and paper industry and in forest biorefineries. The potential in using oxalate decarboxylase from Aspergillus niger for oxalic acid removal in industrial bleaching plant filtrates containing oxalic acid was examined and compared with barley oxalate oxidase. Ten different filtrates from chemical pulping were selected for the evaluation. Oxalate decarboxylase degraded oxalic acid faster than oxalate oxidase in eight of the filtrates, while oxalate oxidase performed better in one filtrate. One of the filtrates inhibited both enzymes. The potential inhibitory effect of selected compounds on the enzymatic activity was tested. Oxalate decarboxylase was more sensitive than oxalate oxidase to hydrogen peroxide. Oxalate decarboxylase was not as sensitive to chlorate and chlorite as oxalate oxidase. Up to 4 mM chlorate ions, the highest concentration tested, had no inhibitory effect on oxalate decarboxylase. Analysis of the filtrates suggests that high concentrations of chlorate present in some of the filtrates were responsible for the higher sensitivity of oxalate oxidase in these filtrates. Oxalate decarboxylase was thus a better choice than oxalate oxidase for treatment of filtrates from chlorine dioxide bleaching. PMID:19763895

Cassland, Pierre; Sjöde, Anders; Winestrand, Sandra; Jönsson, Leif J; Nilvebrant, Nils-Olof

2010-05-01

366

Regulation of tyramine oxidase synthesis in Klebsiella aerogenes.  

PubMed Central

Tyramine oxidase in Klebsiella aerogenes is highly specific for tyramine, dopamine, octopamine, and norepinephrine, and its synthesis is induced specifically by these compounds. The enzyme is present in a membrane-bound form. The Km value for tyramine is 9 X 10(-4) M. Tyramine oxidase synthesis was subjected to catabolite repression by glucose in the presence of ammonium salts. Addition of cyclic adenosine 3',5'-monophosphate (cAMP) overcame the catabolite repression. A mutant strain, K711, which can produce a high level of beta-galactosidase in the presence of glucose and ammonium chloride, can also synthesize tyramine oxidase and histidase in the presence of inducer in glucose ammonium medium. Catabolite repression of tyramine oxidase synthesis was relieved when the cells were grown under conditions of nitrogen limitation, whereas beta-galactosidase was strongly repressed under these conditions. A cAMP-requiring mutant, MK54, synthesized tyramine oxidase rapidly when tyramine was used as the sole source of nitrogen in the absence of cAMP. However, a glutamine synthetase-constitutive mutant, MK94, failed to synthesize tyramine oxidase in the presence of glucose and ammonium chloride, although it synthesized histidase rapidly under these conditions. These results suggest that catabolite repression of tyramine oxidase synthesis in K. aerogenes is regulated by the intracellular level of cAMP and an unknown cytoplasmic factor that acts independently of cAMP and is formed under conditions of nitrogen limitation. PMID:179974

Okamura, H; Murooka, Y; Harada, T

1976-01-01

367

THE PREPARATION AND PROPERTIES OF HIGHLY PURIFIED ASCORBIC ACID OXIDASE  

PubMed Central

1. A method is described for the preparation of a highly purified ascorbic acid oxidase containing 0.24 per cent copper. 2. Using comparable activity measurements, this oxidase is about one and a half times as active on a dry weight basis as the hitherto most highly purified preparation described by Lovett-Janison and Nelson. The latter contained 0.15 per cent copper. 3. The oxidase activity is proportional to the copper content and the proportionality factor is the same as that reported by Lovett-Janison and Nelson. 4. When dialyzed free of salt, the blue concentrated oxidase solutions precipitate a dark green-blue protein which carries the activity. This may be prevented by keeping the concentrated solutions about 0.1 M in Na2HPO4. 5. When highly diluted for activity measurements the oxidase rapidly loses activity (irreversibly) previous to the measurement, unless the dilution is made with a dilute inert protein (gelatin) solution. Therefore activity values obtained using such gelatin-stabilized dilute solutions of the oxidase run considerably higher than values obtained by the Lovett-Janison and Nelson technique. 6. The effect of pH and substrate concentration on the activity of the purified oxidase in the presence and absence of inert protein was studied. PMID:19873382

Powers, Wendell H.; Lewis, Stanley; Dawson, Charles R.

1944-01-01

368

Soft Rot of Rhizopus oryzae as a Postharvest Pathogen of Banana Fruit in Korea  

PubMed Central

Soft rot on banana fruit caused by Rhizopus oryzae was identified for the first time in Korea. Colonies were white to light brown and formed numerous sporangiospores. Optimum temperature for mycelial growth was 30?. Sporangia were globose and 30~200 µm. Sporangiophores were usually straight, 8~20 µm, and rhizoids usually in groups of 3~5. Columella were globose to sub-globose and 90~110 µm. Sporangiospores were sub-globose or oval and 4~10 µm. Based on its mycological characteristics, molecular analysis, and pathogenicity to host plants, this fungus was identified as Rhizopus oryzae Went & Prisen Geerligs. This is the first report of soft rot on banana caused by Rhizopus oryzae in Korea. PMID:23115518

Ryu, Jae-San; Chi, Tran Thi Phuong; Shen, Shun-Shan; Choi, Okhee

2012-01-01

369

A flax-retting endopolygalacturonase-encoding gene from Rhizopus oryzae.  

PubMed

A polygalacturonase from the filamentous fungus Rhizopus oryzae strain sb (NRRL 29086), previously shown to be effective in the retting of flax fibers, was shown by the analysis of its reaction products on polygalacturonic acid to be an endo-type. By zymogram analysis, the enzyme in the crude culture filtrate appeared as two active species of 37 and 40 kD. The endopolygalacturonase-encoding gene was cloned in Escherichia coli and its translated 383-amino acid sequence found to be identical to that of a presumed exopolygalacturonase found in R. oryzae strain YM9901 and 96% identical to a hypothetical protein (RO3G_04731.1) in the sequenced genome of R. oryzae strain 99-880. Phylogenetic analysis revealed the presence of an unique cluster of Rhizopus polygalacturonase sequences that are separate from other fungal polygalacturonases. Conservation of 12 cysteines appears to be a special feature of this family of Rhizopus polygalacturonase sequences. PMID:18704748

Xiao, Zhizhuang; Wang, Shaozhao; Bergeron, Hélčne; Zhang, Jianchun; Lau, Peter C K

2008-11-01

370

Comparative Analysis of the Korean Population of Magnaporthe oryzae by Multilocus Microsatellite Typing  

PubMed Central

Rice blast fungus, Magnaporthe oryzae, inflicts serious damage to global rice production. Due to high variability of this fungal pathogen, resistance of newly-released rice cultivars is easily broken down. To understand the population structure of M. oryzae, we analyzed the genetic diversity of the Korean population using multilocus microsatellite typing. Eleven microsatellite markers were applied to the population of 190 rice isolates which had been collected in Korea for two decades since the 1980’s. Average values of gene diversity and allele frequency were 0.412 and 6.5, respectively. Comparative analysis of the digitized allele information revealed that the Korean population exhibited a similar level of allele diversity to the integrated diversity of the world populations, suggesting a particularly high diversity of the Korean population. Therefore, these microsatellite markers and the comprehensive collection of field isolates will be useful genetic resources to identify the genetic diversity of M. oryzae population.

Choi, Jaehyuk; Kim, Hyojung; Lee, Yong-Hwan

2013-01-01

371

Morphological and molecular characterization of Magnaporthe oryzae (fungus) from infected rice leaf samples  

NASA Astrophysics Data System (ADS)

Magnaporthe oryzae is a plant-pathogenic fungus that causes a serious disease affecting rice called rice blast. Outbreaks of rice blast have been a threat to the global production of rice. This fungal disease is estimated to cause production losses of US55 million each year in South and Southeast Asia. It has been used as a primary model for elucidating various aspects of the host-pathogen interaction with its host. We have isolated five isolates of Magnaporthe oryzae from diseased leaf samples obtained from the field at Kompleks Latihan MADA, Kedah, Malaysia. We have identified the isolates using morphological and microscopic studies on the fungal spores and the lesions on the diseased leaves. Amplification of the internal transcribed spacer (ITS) was carried out with universal primers ITS1 and ITS4. The sequence of each isolates showed at least 99% nucleotide identity with the corresponding sequence in GenBank for Magnaporthe oryzae.

Muni, Nurulhidayah Mat; Nadarajah, Kalaivani

2014-09-01

372

Structural analysis of cerebrosides from Aspergillus fungi: the existence of galactosylceramide in A. oryzae.  

PubMed

Glucosylceramide and galactosylceramide were detected in three Aspergillus species: Aspergillus oryzae, Aspergillus sojae and Aspergillus. awamori, using borate-coated TLC. The cerebrosides from A. oryzae were further purified by ion exchange and iatrobeads column chromatographies with or without borate, and determined the composition of sugar, fatty acid and sphingoid base by GC/MS, MALDI-TOF/MS and (1)H-NMR. We identified them as ?-glucosylceramide and ?-galactosylceramide. The ceramide moiety of both cerebrosides consisted mainly of 2-hydroxystearic acid and either 9-methyl-octadeca-4, 8-sphingadienine or octadeca-4, 8-sphingadienine. To our knowledge, this is the first study to provide evidence for the presence of ?-galactosylceramide in A. oryzae. PMID:25129050

Tani, Yasushi; Amaishi, Yasunori; Funatsu, Tori; Ito, Masahiro; Itonori, Saki; Hata, Yoji; Ashida, Hisashi; Yamamoto, Kenji

2014-12-01

373

The genome sequence of African rice (Oryza glaberrima) and evidence for independent domestication.  

PubMed

The cultivation of rice in Africa dates back more than 3,000 years. Interestingly, African rice is not of the same origin as Asian rice (Oryza sativa L.) but rather is an entirely different species (i.e., Oryza glaberrima Steud.). Here we present a high-quality assembly and annotation of the O. glaberrima genome and detailed analyses of its evolutionary history of domestication and selection. Population genomics analyses of 20 O. glaberrima and 94 Oryza barthii accessions support the hypothesis that O. glaberrima was domesticated in a single region along the Niger river as opposed to noncentric domestication events across Africa. We detected evidence for artificial selection at a genome-wide scale, as well as with a set of O. glaberrima genes orthologous to O. sativa genes that are known to be associated with domestication, thus indicating convergent yet independent selection of a common set of genes during two geographically and culturally distinct domestication processes. PMID:25064006

Wang, Muhua; Yu, Yeisoo; Haberer, Georg; Marri, Pradeep Reddy; Fan, Chuanzhu; Goicoechea, Jose Luis; Zuccolo, Andrea; Song, Xiang; Kudrna, Dave; Ammiraju, Jetty S S; Cossu, Rosa Maria; Maldonado, Carlos; Chen, Jinfeng; Lee, Seunghee; Sisneros, Nick; de Baynast, Kristi; Golser, Wolfgang; Wissotski, Marina; Kim, Woojin; Sanchez, Paul; Ndjiondjop, Marie-Noelle; Sanni, Kayode; Long, Manyuan; Carney, Judith; Panaud, Olivier; Wicker, Thomas; Machado, Carlos A; Chen, Mingsheng; Mayer, Klaus F X; Rounsley, Steve; Wing, Rod A

2014-09-01

374

Plastid terminal oxidase 2 (PTOX2) is the major oxidase involved in chlororespiration in Chlamydomonas  

PubMed Central

By homology with the unique plastid terminal oxidase (PTOX) found in plants, two genes encoding oxidases have been found in the Chlamydomonas genome, PTOX1 and PTOX2. Here we report the identification of a knockout mutant of PTOX2. Its molecular and functional characterization demonstrates that it encodes the oxidase most predominantly involved in chlororespiration in this algal species. In this mutant, the plastoquinone pool is constitutively reduced under dark-aerobic conditions, resulting in the mobile light-harvesting complexes being mainly, but reversibly, associated with photosystem I. Accordingly, the ptox2 mutant shows lower fitness than wild type when grown under phototrophic conditions. Single and double mutants devoid of the cytochrome b6f complex and PTOX2 were used to measure the oxidation rates of plastoquinols via PTOX1 and PTOX2. Those lacking both the cytochrome b6f complex and PTOX2 were more sensitive to light than the single mutants lacking either the cytochrome b6f complex or PTOX2, which discloses the role of PTOX2 under extreme conditions where the plastoquinone pool is overreduced. A model for chlororespiration is proposed to relate the electron flow rate through these alternative pathways and the redox state of plastoquinones in the dark. This model suggests that, in green algae and plants, the redox poise results from the balanced accumulation of PTOX and NADPH dehydrogenase. PMID:22143777

Houille-Vernes, Laura; Rappaport, Fabrice; Wollman, Francis-Andre; Alric, Jean; Johnson, Xenie

2011-01-01

375

Visualization of monoamine oxidase in human brain  

SciTech Connect

Monoamine oxidase is a flavin enzyme which exists in two subtypes, MAO A and MAO B. In human brain MAO B predominates and is largely compartmentalized in cell bodies of serotonergic neurons and glia. Regional distribution of MAO B was determined by positron computed tomography with volunteers after the administration of deuterium substituted [11C]L-deprenyl. The basal ganglia and thalamus exhibited the greatest concentrations of MAO B with intermediate levels in the frontal cortex and cingulate gyrus while lowest levels were observed in the parietal and temporal cortices and cerebellum. We observed that brain MAO B increases with are in health normal subjects, however the increases were generally smaller than those revealed with post-mortem studies.

Fowler, J.S.; Volkow, N.D.; Wang, G.J.; Pappas, N.; Shea, C.; MacGregor, R.R.; Logan, J.

1996-12-31

376

Cholesterol oxidase: biochemistry and structural features.  

PubMed

Cholesterol oxidases are bifunctional flavoenzymes that catalyze the oxidation of steroid substrates which have a hydroxyl group at the 3beta position of the steroid ring system. The enzyme is found, in a wide range of bacterial species, in two forms: one with the FAD cofactor bound noncovalently to the enzyme; and one with the cofactor linked covalently to the protein. Here we discuss, compare and contrast the salient biochemical properties of the two forms of the enzyme. Specifically, the structural features are discussed that affect the redox potentials of the flavin cofactor, the chemical mechanism of substrate dehydrogenation by active-center amino acid residues, the kinetic parameters of both types of enzymes and the reactivity of reduced enzymes with molecular dioxygen. The presence of a molecular tunnel that is proposed to serve in the access of dioxygen to the active site and mechanisms of its control by a 'gate' formed by amino acid residues are highlighted. PMID:19843169

Vrielink, Alice; Ghisla, Sandro

2009-12-01

377

Modeling dioxygen reduction at multicopper oxidase cathodes.  

PubMed

We report a general kinetics model for catalytic dioxygen reduction on multicopper oxidase (MCO) cathodes. Our rate equation combines Butler-Volmer (BV) electrode kinetics and the Michaelis-Menten (MM) formalism for enzymatic catalysis, with the BV model accounting for interfacial electron transfer (ET) between the electrode surface and the MCO type 1 copper site. Extending the principles of MM kinetics to this system produced an analytical expression incorporating the effects of subsequent intramolecular ET and dioxygen binding to the trinuclear copper cluster into the cumulative model. We employed experimental electrochemical data on Thermus thermophilus laccase as benchmarks to validate our model, which we suggest will aid in the design of more efficient MCO cathodes. In addition, we demonstrate the model's utility in determining estimates for both the electronic coupling and average distance between the laccase type-1 active site and the cathode substrate. PMID:25188422

Agbo, Peter; Heath, James R; Gray, Harry B

2014-10-01

378

The tillering phenotype of the rice plastid terminal oxidase (PTOX) loss-of-function mutant is associated with strigolactone deficiency.  

PubMed

The significance of plastid terminal oxidase (PTOX) in phytoene desaturation and chloroplast function has been demonstrated using PTOX-deficient mutants, particularly in Arabidopsis. However, studies on its role in monocots are lacking. Here, we report cloning and characterization of the rice (Oryza sativa) PTOX1 gene. Using Ecotype Targeting Induced Local Lesions IN Genomes (EcoTILLING) and TILLING as forward genetic tools, we identified the causative mutation of an EMS mutant characterized by excessive tillering, semi-dwarfism and leaf variegation that corresponded to the PTOX1 gene. The tillering and semi-dwarf phenotypes of the ptox1 mutant are similar to phenotypes of known strigolactone (SL)-related rice mutants, and both phenotypic traits could be rescued by application of the synthetic SL GR24. The ptox1 mutant accumulated phytoene in white leaf sectors with a corresponding deficiency in ?-carotene, consistent with the expected function of PTOX1 in promoting phytoene desaturase activity. There was also no accumulation of the carotenoid-derived SL ent-2'-epi-5-deoxystrigol in root exudates. Elevated concentrations of auxin were detected in the mutant, supporting previous observations that SL interaction with auxin is important in shoot branching control. Our results demonstrate that PTOX1 is required for both carotenoid and SL synthesis resulting in SL-deficient phenotypes in rice. PMID:24350905

Tamiru, Muluneh; Abe, Akira; Utsushi, Hiroe; Yoshida, Kakoto; Takagi, Hiroki; Fujisaki, Koki; Undan, Jerwin R; Rakshit, Sujay; Takaichi, Shinichi; Jikumaru, Yusuke; Yokota, Takao; Terry, Matthew J; Terauchi, Ryohei

2014-04-01

379

The mitochondrial cyanide-resistant oxidase: structural conservation amid regulatory diversity  

Microsoft Academic Search

Mitochondria from all plants, many fungi and some protozoa contain a cyanide-resistant, alternative oxidase that functions in parallel with cytochrome c oxidase as the terminal oxidase on the electron transfer chain. Characterization of the structural and potential regulatory features of the alternative oxidase has advanced considerably in recent years. The active site is proposed to contain a di-iron center belonging

James N Siedow; Ann L Umbach

2000-01-01

380

Distribution of oxidases in the testis of buffalo, goat and ram : an histochemical study  

E-print Network

. Peroxidase, monoamine oxidase (MAO) and cytochrome oxidase (CCO) have been histochemically localized of monoamine oxidase (MAO) has been reported in the rat testis (Bhagvat et al., 1939 ; Zeller and Joel, 1941Distribution of oxidases in the testis of buffalo, goat and ram : an histochemical study G. S

Boyer, Edmond

381

Gibberellin oxidase activities in Bradyrhizobium japonicum bacteroids.  

PubMed

Bradyrhizobium japonicum bacteroids isolated from root nodules of soybean (Glycine max.) plants converted the gibberellin (GA) precursor [(14)C1]GA12 into several products identified by combined gas chromatography-mass spectrometry as [(14)C1]GA24, [(14)C1]GA9, [(14)C1]GA15, GA9 17-nor-16-one and unidentified products. The oxidation of GA12, catalyzed by the GA 20-oxidase, was present in symbiotic bacteroids from plants around flowering, but not in bacteroids from plants at either an early vegetative stage or at late growth stages. Expression of cps and ks genes, involved in ent-kaurene biosynthesis, was also demonstrated in bacteroids from soybean plants around flowering. Earlier precursors of the GA pathway, ent-[(14)C1]kaurenoic acid or [(14)C4]GA12-aldehyde, were efficiently utilized by B. japonicum bacteroids to give labelled GA9 plus intermediates partially oxidized at C-20, as well as GA9 17-nor-16-one and an unidentified product. No 3? or 13-hydroxylated [(14)C]GAs were detected in any of the incubations. Moreover the C19-GAs [(14)C1]GA4 or [(14)C1]GA20 were recovered unconverted upon incubation with the bacteroids which supports the absence of GA 3?-hydroxylase activity in B. japonicum. The bacterial 20-oxidase utilized the 13-hydroxylated substrates [(14)C1]GA53, [(14)C1]GA44 or [(14)C1]GA19, although with less efficiency than [(14)C1]GA12 to give [(14)C1]GA20 as final product, while the 3?-hydroxylated substrate [(14)C1]GA14 was converted to [(14)C1]GA4 to a very small extent. Endogenous GA9 and GA24 were identified by GC-MS in methanolic nodule extracts. These results suggest that B. japonicum bacteroids would synthesize GA9 under the symbiotic conditions present in soybean root nodules. PMID:24378220

Méndez, Constanza; Baginsky, Cecilia; Hedden, Peter; Gong, Fan; Carú, Margarita; Rojas, María Cecilia

2014-02-01

382

Preparation, structure and coordination properties of (? 6- p-cymene)ruthenium(II) sandwich complexes of catechol and 5-hydroxyindole derivatives  

Microsoft Academic Search

Bis(?6-arene)ruthenium(II) complexes of the type [(?6-cymene)Ru(?6-L)](CF3SO3)n (2–7), n=2–3, containing catechol and 5-hydroxyindole derivatives L may be prepared by treatment of [(?6-cymene)Ru(acetone)3](CF3SO3)2 with the appropriate compound in CF3COOH. For the l-Dopa and H-dopamine complexes 2 (n=2) and 3 (n=3), ?6-coordination leads to a dramatic reduction of more than 6 units in pKa to values of, respectively 3.67(3) and 3.98(7) for the

Anke Schlüter; Kirsten Bieber; William S Sheldrick

2002-01-01

383

Electrochemical storage: catechol-mediated reversible binding of multivalent cations in eumelanin half-cells (adv. Mater. 38/2014).  

PubMed

Biologically derived polymers from the cuttlefish can be leveraged as sustainable energy-storage materials. Melanin pigments exhibit redox-active chemistries and homogeneous nanostructured particles. Catechols can be oxidized into ortho-quinones and reversibly bind magnesium cations with differential affinity as described by J. F. Whitacre, C. J. Bettinger, and co-workers on page 6572. These properties of melanin biopolymers are advantageous for the potential use as cathodes in rechargeable magnesium ion batteries with high cycle stability. Photo credit: Brent Polishak. PMID:25302643

Kim, Young Jo; Wu, Wei; Chun, Sang-Eun; Whitacre, Jay F; Bettinger, Christopher J

2014-10-01

384

Computationally-Guided Optimization of a Docking Hit to Yield Catechol Diethers as Potent Anti-HIV Agents  

PubMed Central

A 5-?M docking hit has been optimized to an extraordinarily potent (55 pM) non-nucleoside inhibitor of HIV reverse transcriptase. Use of free energy perturbation (FEP) calculations to predict relative free energies of binding aided the optimizations by identifying optimal substitution patterns for phenyl rings and a linker. The most potent resultant catechol diethers feature terminal uracil and cyanovinylphenyl groups. A halogen bond with Pro95 likely contributes to the extreme potency of compound 42. In addition, several examples are provided illustrating failures of attempted grafting of a substructure from a very active compound onto a seemingly related scaffold to improve its activity. PMID:22081993

Bollini, Mariela; Domaoal, Robert A.; Thakur, Vinay V.; Gallardo-Macias, Ricardo; Spasov, Krasimir A.; Anderson, Karen S.; Jorgensen, William L.

2011-01-01

385

Media-Dependent Oxidase Reaction ina Strain of Aeromonas hydrophila  

Microsoft Academic Search

MembersofthegenusAeromonas arede- fined asgram-negative, nonsporeforming rods (1.0 to3.5,umlongx0.4to1.0,umwide) which maybemotile bymeansofpolar flagella. They ferment glucose andother carbohydrates and produce indophenol oxidase (2). Thepositive oxidase test isusedtoseparate aeromonads and vibrios fromtheglucose-fermenting, oxidase- negative Enterobacteriaceae. Iftheoxidase test isnotroutinely performed onisolates ofglu- cose-fermenting gram-negative rods, itisquite possible tomisidentify Aeromonas hydrophila asEscherichia coli orSerratia andAeromonas shigelloides asShigella sonnei (2). Wewouldlike toreport ontheisolation from bile

SUE B. OVERMAN; TIMOTHY L. OVERMAN

1977-01-01

386

Multilayered Polyelectrolyte Microcapsules: Interaction with the Enzyme Cytochrome C Oxidase  

PubMed Central

Cell-sized polyelectrolyte capsules functionalized with a redox-driven proton pump protein were assembled for the first time. The interaction of polyelectrolyte microcapsules, fabricated by electrostatic layer-by-layer assembly, with cytochrome c oxidase molecules was investigated. We found that the cytochrome c oxidase retained its functionality, that the functionalized microcapsules interacting with cytochrome c oxidase were permeable and that the permeability characteristics of the microcapsule shell depend on the shell components. This work provides a significant input towards the fabrication of an integrated device made of biological components and based on specific biomolecular functions and properties. PMID:25372607

Pastorino, Laura; Dellacasa, Elena; Noor, Mohamed R.; Soulimane, Tewfik; Bianchini, Paolo; D'Autilia, Francesca; Antipov, Alexei; Diaspro, Alberto; Tofail, Syed A. M.; Ruggiero, Carmelina

2014-01-01

387

CotA, a Multicopper Oxidase from Bacillus pumilus WH4, Exhibits Manganese-Oxidase Activity  

PubMed Central

Multicopper oxidases (MCOs) are a family of enzymes that use copper ions as cofactors to oxidize various substrates. Previous research has demonstrated that several MCOs such as MnxG, MofA and MoxA can act as putative Mn(II) oxidases. Meanwhile, the endospore coat protein CotA from Bacillus species has been confirmed as a typical MCO. To study the relationship between CotA and the Mn(II) oxidation, the cotA gene from a highly active Mn(II)-oxidizing strain Bacillus pumilus WH4 was cloned and overexpressed in Escherichia coli strain M15. The purified CotA contained approximately four copper atoms per molecule and showed spectroscopic properties typical of blue copper oxidases. Importantly, apart from the laccase activities, the CotA also displayed substantial Mn(II)-oxidase activities both in liquid culture system and native polyacrylamide gel electrophoresis. The optimum Mn(II) oxidase activity was obtained at 53°C in HEPES buffer (pH 8.0) supplemented with 0.8 mM CuCl2. Besides, the addition of o-phenanthroline and EDTA both led to a complete suppression of Mn(II)-oxidizing activity. The specific activity of purified CotA towards Mn(II) was 0.27 U/mg. The Km, Vmax and kcat values towards Mn(II) were 14.85±1.17 mM, 3.01×10?6±0.21 M·min?1 and 0.32±0.02 s?1, respectively. Moreover, the Mn(II)-oxidizing activity of the recombinant E. coli strain M15-pQE-cotA was significantly increased when cultured both in Mn-containing K liquid medium and on agar plates. After 7-day liquid cultivation, M15-pQE-cotA resulted in 18.2% removal of Mn(II) from the medium. Furthermore, the biogenic Mn oxides were clearly observed on the cell surfaces of M15-pQE-cotA by scanning electron microscopy. To our knowledge, this is the first report that provides the direct observation of Mn(II) oxidation with the heterologously expressed protein CotA, Therefore, this novel finding not only establishes the foundation for in-depth study of Mn(II) oxidation mechanisms, but also offers a potential biocatalyst for Mn(II) removal. PMID:23577125

Su, Jianmei; Bao, Peng; Bai, Tenglong; Deng, Lin; Wu, Hui; Liu, Fan; He, Jin

2013-01-01

388

CotA, a multicopper oxidase from Bacillus pumilus WH4, exhibits manganese-oxidase activity.  

PubMed

Multicopper oxidases (MCOs) are a family of enzymes that use copper ions as cofactors to oxidize various substrates. Previous research has demonstrated that several MCOs such as MnxG, MofA and MoxA can act as putative Mn(II) oxidases. Meanwhile, the endospore coat protein CotA from Bacillus species has been confirmed as a typical MCO. To study the relationship between CotA and the Mn(II) oxidation, the cotA gene from a highly active Mn(II)-oxidizing strain Bacillus pumilus WH4 was cloned and overexpressed in Escherichia coli strain M15. The purified CotA contained approximately four copper atoms per molecule and showed spectroscopic properties typical of blue copper oxidases. Importantly, apart from the laccase activities, the CotA also displayed substantial Mn(II)-oxidase activities both in liquid culture system and native polyacrylamide gel electrophoresis. The optimum Mn(II) oxidase activity was obtained at 53°C in HEPES buffer (pH 8.0) supplemented with 0.8 mM CuCl2. Besides, the addition of o-phenanthroline and EDTA both led to a complete suppression of Mn(II)-oxidizing activity. The specific activity of purified CotA towards Mn(II) was 0.27 U/mg. The Km, Vmax and kcat values towards Mn(II) were 14.85±1.17 mM, 3.01×10(-6)±0.21 M·min(-1) and 0.32±0.02 s(-1), respectively. Moreover, the Mn(II)-oxidizing activity of the recombinant E. coli strain M15-pQE-cotA was significantly increased when cultured both in Mn-containing K liquid medium and on agar plates. After 7-day liquid cultivation, M15-pQE-cotA resulted in 18.2% removal of Mn(II) from the medium. Furthermore, the biogenic Mn oxides were clearly observed on the cell surfaces of M15-pQE-cotA by scanning electron microscopy. To our knowledge, this is the first report that provides the direct observation of Mn(II) oxidation with the heterologously expressed protein CotA, Therefore, this novel finding not only establishes the foundation for in-depth study of Mn(II) oxidation mechanisms, but also offers a potential biocatalyst for Mn(II) removal. PMID:23577125

Su, Jianmei; Bao, Peng; Bai, Tenglong; Deng, Lin; Wu, Hui; Liu, Fan; He, Jin

2013-01-01

389

Penetration and post-penetration resistance to Magnaporthe oryzae in Arabidopsis.  

PubMed

The rate of entry of Magnaporthe oryzae into the Arabidopsis pen2 quintuple (pen2 NahG pmr5 agb1 mlo2) mutant was significantly higher than those into the pen2 quadruple (pen2 NahG pmr5 agb1 and pen2 NahG pmr5 mlo2) mutants. The lengths of the infection hyphae in the pen2 quintuple mutant were intermediate between the pen2 quadruple mutants. These results suggest that different genetic networks, consisting of PEN2, PMR5, AGB1, and MLO2, control penetration and post-penetration resistance to M. oryzae in Arabidopsis. PMID:23924716

Okawa, Chiharu; Nakao, Misato; Ishikawa, Atsushi

2013-01-01

390

MPK6 contributes to non-host resistance to magnaporthe oryzae in Arabidopsis thaliana.  

PubMed

The rate of entry of Magnaporthe oryzae into pen2 mpk6 plants was higher than that into pen2 plants. The infection hyphae in the pen2 mpk6 plants were longer than those in the pen2 plants. The proportion of branched hyphae development in the pen2 mpk6 plants was higher than that in the pen2 plants. These results suggest that MPK6 functions in both penetration and post-penetration resistance to M. oryzae in Arabidopsis thaliana. PMID:23748771

Okawa, Chiharu; Ishikawa, Atsushi

2013-01-01

391

Bioluminescence Imaging of NADPH Oxidase Activity in Different Animal Models  

PubMed Central

NADPH oxidase is a critical enzyme that mediates antibacterial and antifungal host defense. In addition to its role in antimicrobial host defense, NADPH oxidase has critical signaling functions that modulate the inflammatory response 1. Thus, the development of a method to measure in "real-time" the kinetics of NADPH oxidase-derived ROS generation is expected to be a valuable research tool to understand mechanisms relevant to host defense, inflammation, and injury. Chronic granulomatous disease (CGD) is an inherited disorder of the NADPH oxidase characterized by severe infections and excessive inflammation. Activation of the phagocyte NADPH oxidase requires translocation of its cytosolic subunits (p47phox, p67phox, and p40phox) and Rac to a membrane-bound flavocytochrome (composed of a gp91phox and p22phox heterodimer). Loss of function mutations in any of these NADPH oxidase components result in CGD. Similar to patients with CGD, gp91phox -deficient mice and p47phox-deficient mice have defective phagocyte NADPH oxidase activity and impaired host defense 2, 13. In addition to phagocytes, which contain the NADPH oxidase components described above, a variety of other cell types express different isoforms of NADPH oxidase. Here, we describe a method to quantify ROS production in living mice and to delineate the contribution of NADPH oxidase to ROS generation in models of inflammation and injury. This method is based on ROS reacting with L-012 (an analogue of luminol) to emit luminescence that is recorded by a charge-coupled device (CCD). In the original description of the L-012 probe, L-012-dependent chemiluminescence was completely abolished by superoxide dismutase, indicating that the main ROS detected in this reaction was superoxide anion 14. Subsequent studies have shown that L-012 can detect other free radicals, including reactive nitrogen species 15, 16. Kielland et al.16 showed that topical application of phorbol myristate acetate, a potent activator of NADPH oxidase, led to NADPH oxidase-dependent ROS generation that could be detected in mice using the luminescent probe L-012. In this model, they showed that L-012-dependent luminescence was abolished in p47phox-deficient mice. We compared ROS generation in wildtype mice and NADPH oxidase-deficient p47phox-/- mice 2 in the following three models: 1) intratracheal administration of zymosan, a pro-inflammatory fungal cell wall-derived product that can activate NADPH oxidase; 2) cecal ligation and puncture (CLP), a model of intra-abdominal sepsis with secondary acute lung inflammation and injury; and 3) oral carbon tetrachloride (CCl4), a model of ROS-dependent hepatic injury. These models were specifically selected to evaluate NADPH oxidase-dependent ROS generation in the context of non-infectious inflammation, polymicrobial sepsis, and toxin-induced organ injury, respectively. Comparing bioluminescence in wildtype mice to p47phox-/- mice enables us to delineate the specific contribution of ROS generated by p47phox-containing NADPH oxidase to the bioluminescent signal in these models. Bioluminescence imaging results that demonstrated increased ROS levels in wildtype mice compared to p47phox-/- mice indicated that NADPH oxidase is the major source of ROS generation in response to inflammatory stimuli. This method provides a minimally invasive approach for "real-time" monitoring of ROS generation during inflammation in vivo. PMID:23117583

Han, Wei; Li, Hui; Segal, Brahm H.; Blackwell, Timothy S.

2012-01-01

392

Allopurinol metabolism in a patient with xanthine oxidase deficiency.  

PubMed Central

A patient with complete deficiency of xanthine oxidase would not be expected to oxidase allopurinol to oxipurinol if allopurinol did not have any alternative metabolic pathway. 400 mg of allopurinol was administered to a patient with xanthine oxidase deficiency, and plasma allopurinol, oxipurinol, hypoxanthine, and xanthine levels were determined serially by the use of high-performance liquid chromatography (HPLC). Plasma oxipurinol as well as allopurinol was increased after the administration of allopurinol, and oxipurinol reached a maximum level of 13.1 micrograms/ml at 6 hours after the administration. This was the same pattern as that of normal controls. This result demonstrated the existence of some other oxidising enzyme of allopurinol than xanthine oxidase. PMID:6689118

Yamanaka, H; Nishioka, K; Suzuki, T; Kohno, K

1983-01-01

393

Import of alcohol oxidase into peroxisomes of Saccharomyces cerevisiae.  

PubMed Central

Saccharomyces cerevisiae is unable to grow on methanol because it lacks the enzymes required for its metabolism. To study the possibility of whether or not the methanol oxidation pathway of Hansenula polymorpha can be transferred to S. cerevisiae, the gene coding for alcohol oxidase, a peroxisomal homo-octameric flavoprotein, was introduced into S. cerevisiae. Transformed cells contain varying amounts of alcohol oxidase depending on the plasmid used. Immunocytochemical experiments indicate that the protein is imported into peroxisomes, whether organelle proliferation is induced or not. Cells lack alcohol oxidase activity however, and only the monomeric, non-functional, form of the protein is found. These findings indicate that the H. polymorpha peroxisomal targeting signal of alcohol oxidase is recognized in S. cerevisiae and protein monomers are imported. Images Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. PMID:2826130

Distel, B; Veenhuis, M; Tabak, H F

1987-01-01

394

2-Arylthiomorpholine derivatives as potent and selective monoamine oxidase .  

E-print Network

??2-Arylthiomorpholine and 2-arylthiomorpholin-5-one derivatives, designed as rigid and/or non-basic phenylethylamine analogues, were evaluated as rat and human monoamine oxidase inhibitors. Molecular docking provided insight into… (more)

Lühr Sierra, Susan

2010-01-01

395

Naphthylisopropylamine and N-benzylamphetamine derivatives as monoamine oxidase inhibitors .  

E-print Network

??A series of naphthylisopropylamine and N-benzyl-4-methylthioamphetamine derivatives were evaluated as monoamine oxidase inhibitors. Their potencies were compared with those of a series of amphetamine derivatives,… (more)

Vilches-Herrera, Marcelo

2009-01-01

396

Genetics Home Reference: Peroxisomal acyl-CoA oxidase deficiency  

MedlinePLUS

... gov Research studies PubMed Recent literature OMIM Genetic disorder catalog Conditions > Peroxisomal acyl-CoA oxidase deficiency On this page: Description Genetic changes Inheritance Diagnosis Additional information Other names Glossary definitions Reviewed April ...

397

Non-innocent ligand behaviour of a bimetallic Cu complex employing a bridging catecholate.  

PubMed

The geometric and electronic structure of a bimetallic Cu Schiff-base complex and its one-electron oxidized form have been investigated. The two salen units in the neutral complex 1 are linked via a bridging catecholate function, and the coupling between the two Cu(II) d(9) centres was determined to be weakly antiferromagnetic on the basis of solid-state magnetic studies (J = -3 cm(-1)), and variable-temperature electron paramagnetic resonance (EPR) (J = -3 cm(-1)). Theoretical calculations (DFT) were in agreement with the experimental results (J = -7 cm(-1)), and provided insight into the coupling mechanism for the neutral system. One-electron oxidation provided [1](+) which was observed to have limited stability in solution. The oxidized complex was determined to be a ligand radical species in solution, with the electron hole potentially localized on the redox-active dioxolene, the phenolate ligands, or delocalized over the entire ligand system. Electrochemical experiments and UV-vis-NIR spectroscopy, in combination with density functional theory (DFT) calculations, provided insight into the locus of oxidation and the degree of delocalization in this system. The ligand radical for [1?](+) was determined experimentally to be localized on the dioxolene bridge with a small amount of spin density on the outer phenolate moieties predicted by the calculations. This assignment was aided via comparison to data for the Ni analogue (Inorg. Chem., 2011, 50, 6746). The resonance Raman spectrum of [1?](+) (?(ex) = 413 nm) in CH(2)Cl(2) solution clearly exhibited a new band at 1308 cm(-1) in comparison to 1, supporting semiquinone formation. Variable-temperature EPR on the three-spin system [1?](+) did not provide definitive information on the coupling interaction, possibly due to a very small difference in energy between the S = 3/2 and S = 1/2 states and/or a very small zero-field splitting, in combination with significant line-broadening. The data is consistent with a description of the overall electronic structure of [1?](+) as a bimetallic Cu(II) complex with a bridge-localized semiquinone ligand radical species. PMID:22576939

Dunn, Tim J; Chiang, Linus; Ramogida, Caterina F; Webb, Michael I; Savard, Didier; Sakaguchi, Miyuki; Ogura, Takashi; Shimazaki, Yuichi; Storr, Tim

2012-07-14

398

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

PubMed

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 over the range of concentrations examined, the augmented effects were linearly proportional to the amount of added reductant for a given amount of iron in the system. The pro-oxidant activity of thiols and ascorbate reduced and recycled iron providing both hydrogen peroxide (H2O2) and catalytic ferrous ions for augmented .OH production by the Fenton reaction. The enhanced production of .OH by catechols resulted from their oxidation either by molecular oxygen or ferric ions, with the accompanying formation of semiquinones, superoxide anion and H2O2. These data caution against therapeutic applications of thiols and ascorbate for ameliorating oxy-radical-induced tissue damage in environments where free redox-active metal ions may be present to function both as foci for site-specific peroxidative activity, and as catalysts to promote the pro-oxidant properties of certain endogenous reductants, thereby elevating rather than diminishing .OH levels. PMID:9305802

Nappi, A J; Vass, E

1997-08-29

399

The Vibrio cholerae VctPDGC System Transports Catechol Siderophores and a Siderophore-Free Iron Ligand  

PubMed Central

Vibrio cholerae, the causative agent of cholera, has an absolute requirement for iron. It transports the catechol siderophores vibriobactin, which it synthesizes and secretes, and enterobactin. These siderophores are transported across the inner membrane by one of two periplasmic binding protein-dependent ABC transporters, VctPDGC or ViuPDGC. We show here that one of these inner membrane transport systems, VctPDGC, also promotes iron acquisition in the absence of siderophores. Plasmids carrying the vctPDGC genes stimulated growth in both rich and minimal media of a Shigella flexneri mutant that produces no siderophores. vctPDGC also stimulated the growth of an E. coli enterobactin biosynthetic mutant in low iron medium, and this effect did not require feoB, tonB or aroB. A tyrosine to phenylalanine substitution in the periplasmic binding protein VctP did not alter enterobactin transport, but eliminated growth stimulation in the absence of a siderophore. These data suggest that the VctPDGC system has the capacity to transport both catechol siderophores and a siderophore-free iron ligand. We also show that VctPDGC is the previously unidentified siderophore-independent iron transporter in V. cholerae, and this appears to complete the list of iron transport systems in V. cholerae. PMID:21790806

Wyckoff, Elizabeth E.; Payne, Shelley M.

2011-01-01

400

Anodic electrochemiluminescence of CdTe quantum dots and its energy transfer for detection of catechol derivatives.  

PubMed

This work reported for the first time the anodic electrochemiluminescence (ECL) of CdTe quantum dots (QDs) in aqueous system and its analytical application based on the ECL energy transfer to analytes. The CdTe QDs were modified with mercaptopropionic acid to obtain water-soluble QDs and stable and intensive anodic ECL emission with a peak value at +1.17 V (vs Ag/AgCl) in pH 9.3 PBS at an indium tin oxide (ITO) electrode. The ECL emission was demonstrated to involve the participation of superoxide ion produced at the ITO surface, which could inject an electron into the 1Se quantum-confined orbital of CdTe to form QDs anions. The collision between these anions and the oxidation products of QDs led to the formation of the excited state of QDs and ECL emission. The ECL energy transfer from the excited CdTe QDs to quencher produced a novel methodology for detection of catechol derivatives. Using dopamine and L-adrenalin as model analytes, this ECL method showed wide linear ranges from 50 nM to 5 microM and 80 nM to 30 microM for these species. Both ascorbic acid and uric acid, which are common interferences, did not interfere with the detection of catechol derivatives in practical biological samples. PMID:17910416

Liu, Xuan; Jiang, Hui; Lei, Jianping; Ju, Huangxian

2007-11-01

401

Highly selective suppression of melanoma cells by inducible DNA cross-linking agents: bis(catechol) derivatives.  

PubMed

A series of bis(catechol) quaternary ammonium derivatives were designed and synthesized. We investigated their ability to cross-link DNA induced by tyrosinase and found that the o-quinone is key intermediate in the process by using the nucleophile 3-methyl-2-benzothiazolinone hydrazone (MBTH) in the tyrosinase assay. Their cytotoxicities to B16F1, Hela, and CHO cells were tested by MTT assays. The specific and potent abilities to kill the tyrosinase-efficient melanoma cells kindled our interest in exploring the relationship between their abilities of cross-linking DNA and their selective cytotoxicities to cells. Through an integrated approach including intracellular imaging for detection of the dihydroxyphenyl groups, alkaline comet assays, and ?-H2AX immunofluorescence assays, the speculation was confirmed. The bis(catechol) quaternary ammonium derivatives showed notable cell selectivity because they displayed cytotoxicities after being oxidized by tyrosinase, and they were able to target the DNA efficiently in the tyrosinase-efficient melanoma cells, forming both alkylated and cross-linked species. PMID:20939569

Bai, Minghui; Huang, Jing; Zheng, Xiaolong; Song, Zhibin; Tang, Miru; Mao, Wuxiang; Yuan, Libo; Wu, Jun; Weng, Xiaocheng; Zhou, Xiang

2010-11-01

402

Catechol-functionalized chitosan/iron oxide nanoparticle composite inspired by mussel thread coating and squid beak interfacial chemistry.  

PubMed

Biological materials offer a wide range of multifunctional and structural properties that are currently not achieved in synthetic materials. Herein we report on the synthesis and preparation of bioinspired organic/inorganic composites that mimic the key physicochemical features associated with the mechanical strengthening of both squid beaks and mussel thread coatings using chitosan as an initial template. While chitosan is a well-known biocompatible material, it suffers from key drawbacks that have limited its usage in a wider range of structural biomedical applications. First, its load-bearing capability in hydrated conditions remains poor, and second it completely dissolves at pH < 6, preventing its use in mild acidic microenvironments. In order to overcome these intrinsic limitations, a chitosan-based organic/inorganic biocomposite is prepared that mimics the interfacial chemistry of squid beaks and mussel thread coating. Chitosan was functionalized with catechol moieties in a highly controlled fashion and combined with superparamagnetic iron oxide (?-Fe2O3) nanoparticles to give composites that represent a significant improvement in functionality of chitosan-based biomaterials. The inorganic/organic (?-Fe2O3/catechol) interfaces are stabilized and strengthened by coordination bonding, resulting in hybrid composites with improved stability at high temperatures, physiological pH conditions, and acid/base conditions. The inclusion of superparamagnetic particles also makes the composites stimuli-responsive. PMID:23865752

Zvarec, Ondrej; Purushotham, Sreekanth; Masic, Admir; Ramanujan, Raju V; Miserez, Ali

2013-08-27

403

Significance of the Henri-Michaelis-Menten theory in abiotic catalysis: catechol oxidation by ?-MnO 2  

NASA Astrophysics Data System (ADS)

The Henri-Michaelis-Menten theory, for more than eight decades, was only restricted to homogeneous enzymatic catalysis. A mimic of an enzymatic kinetics based on the Henri-Michaelis-Menten concept was experimentally observed in heterogeneous catalysis in the present study with ?-MnO 2 as an abiotic catalyst in the oxidation of catechol (1,2-dihydroxybenzene). Using the derived linear forms of Lineweaver-Burk or Hofstee, the data show that similar to the enzyme tyrosinase, the kinetics of the catechol oxidation catalyzed by ?-MnO 2 can be described by the Henri-Michaelis-Menten equation, V0= VmaxS/( Km+ S), where Vmax is the maximum velocity and Km the concentration of the substrate ( S) corresponding to an initial velocity ( V0) half of Vmax. By analogy to the enzymatic kinetics, the parameters Vmax and Km for an heterogeneous abiotic catalysis were derived for the first time. Further, based on the concentration of the active centers of the mineral oxide, the kinetic constants kcat and kcat/ Km, respectively, representing the turnover frequency and the efficiency of the mineral catalyst, were also determined from the derived general rate equation of Briggs and Haldane. As an abiotic catalyst, ?-MnO 2 has a paramount role in the oxidation of phenolic compounds in soil, sediment and water environments. Therefore, the present observation is of fundamental and practical significance in elucidating the affinity between an abiotic catalyst and a substrate based on the Henri-Michaelis-Menten theory.

Naidja, A.; Huang, P. M.

2002-05-01

404

KdgR, an IClR Family Transcriptional Regulator, Inhibits Virulence Mainly by Repression of hrp Genes in Xanthomonas oryzae pv. oryzae?  

PubMed Central

KdgR has been reported to negatively regulate the genes involved in degradation and metabolization of pectic acid and other extracellular enzymes in soft-rotting Erwinia spp. through direct binding to their promoters. The possible involvement of a KdgR orthologue in virulence by affecting the expression of extracellular enzymes in Xanthomonas oryzae pv. oryzae, the causal agent of rice blight disease, was examined by comparing virulence and regulation of extracellular enzymes between the wild type (WT) and a strain carrying a mutation in putative kdgR (?Xoo0310 mutant). This putative kdgR mutant of X. oryzae pv. oryzae showed increased pathogenicity on rice without affecting the regulation of extracellular enzymes, such as amylase, cellulase, xylanase, and protease. However, the mutant carrying a mutation in an ortholog of xpsL, which encodes the functional secretion machinery for the extracellular enzymes, showed a dramatic decrease in pathogenicity on rice. Both mutants of kdgR and of xpsL orthologs showed higher expression of two major hrp regulatory genes, hrpG and hrpX, and the genes in the hrp operons when grown in hrp-inducing medium. Thus, both genes were shown to be involved in repression of hrp genes. The kdgR ortholog was thought to suppress virulence mainly by repressing the expression of hrp genes without affecting the expression of extracellular enzymes, unlike findings for the kdgR gene in soft-rotting Erwinia spp. On the other hand, xpsL was confirmed to be involved in virulence by promoting the secretion of extracellular enzymes in spite of repressing the expression of the hrp genes. PMID:21984784

Lu, Yao; Rashidul, Islam M.; Hirata, Hisae; Tsuyumu, Shinji

2011-01-01

405

Characterization of human d-amino acid oxidase  

Microsoft Academic Search

d-Amino acid oxidase (DAAO) has been proposed to be involved in the oxidation of d-serine, an allosteric activator of the NMDA-type glutamate receptor in the brain, and to be associated with the onset of schizophrenia. The recombinant human DAAO was expressed in Escherichia coli and was isolated as an active homodimeric flavoenzyme. It shows the properties of the dehydrogenase-oxidase class

Gianluca Molla; Silvia Sacchi; Mariagrazia Bernasconi; Mirella S. Pilone; Kiyoshi Fukui; Loredano Pollegioni

2006-01-01

406

Caffeine metabolism in cystic fibrosis: Enhanced xanthine oxidase activity  

Microsoft Academic Search

Study objective: To characterize the activities of the P450 mixed-function oxidase CYP1A2 as well as the cytosolic enzymes N-acetyltransferase and xanthine oxidase using caffeine as a probe in children with cystic fibrosis compared to age-matched healthy control subjects.Methods: After administration of caffeine (cola beverage) to 12 children with cystic fibrosis (age range, 5 to 11 years) and 12 healthy control

Bettina A Hamelin; Keyi Xu; François Vallé; Luc Manseau; Monique Richer; Marc LeBel; Marc LeBel PharmD

1994-01-01

407

Ripening in papaya fruit is altered by ACC oxidase cosuppression  

Microsoft Academic Search

Papaya (Carica papaya) is a very important crop in many tropical countries but it is highly susceptible to parasitic diseases, physiological disorders,\\u000a mechanical damage and fruit overripening. Here we report a study on ACC oxidase cosuppression and its effects on papaya fruit\\u000a ripening. Papaya ACC oxidase was isolated using PCR and embriogenic cells transformed by biolistic using the CaMV 35S

Rodolfo López-Gómez; Jose Luis Cabrera-Ponce; Luis Jorge Saucedo-Arias; Lorena Carreto-Montoya; Ramon Villanueva-Arce; Juan Carlos Díaz-Perez; Miguel Angel Gómez-Lim; Luis Herrera-Estrella

2009-01-01

408

Activity of neutrophil NADPH oxidase in iron-deficient anemia  

Microsoft Academic Search

This study was designed to measure the effects of iron supplementation on respiratory burst in iron-deficient anemia. The\\u000a performance of neutrophils was evaluated by measuring the activity of NADPH oxidase in 18 patients with iron-deficient anemia\\u000a before and after body iron stores are saturated. The activity of NADPH oxidase was significantly lower in pretreatment patients\\u000a relative to controls (p<0.05). The

Erdal Kurtoglu; Aysegul Ugur; Abdulkerim Kasim Baltaci; Rasim Mogolkoc; Levent Undar

2003-01-01

409

Expression Studies of Gibberellin Oxidases in Developing Pumpkin Seeds  

Microsoft Academic Search

Two cDNA clones, 3-ox and 2-ox, have been isolated from developing pumpkin (Cucurbita maxima) embryos that show significant amino acid homology to gibberellin (GA) 3-oxidases and 2-oxidases, respectively. Recombinant fusion protein of clone 3-ox converted GA12-aldehyde, GA12 ,G A 15 ,G A 24 ,G A 25, and GA9 to GA14-aldehyde, GA14 ,G A 37 ,G A 36 ,G A 13,

Andrea Frisse; Maria Joao Pimenta; Theo Lange

2003-01-01

410

Simultaneous production of glucose oxidase and catalase by Alternaria alternata  

Microsoft Academic Search

A number of factors affecting simultaneous production of cell-bound glucose oxidase and catalase by the fungus Alternaria alternata have been investigated. Consecutive optimization of the type and concentration of nitrogen and carbon source, the initial pH and growth temperature resulted in a simultaneous increase in glucose oxidase and catalase by 780% and 68% respectively. Two second-order equations, describing the combined

Konstantina-Anna Caridis; Paul Christakopoulos; Basil J. Macris

1991-01-01

411

The broad bacterial blight resistance of rice line CBB23 is triggered by a novel transcription activator-like (TAL) effector of Xanthomonas oryzae pv. oryzae.  

PubMed

Bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), is not only a disease devastating rice production worldwide, but also an ideal model system for the study of the interaction between plants and their bacterial pathogens. The rice near-isogenic line (NIL) CBB23, derived from a cross between a wild rice Oryza rufipogon accession (RBB16) and a susceptible indica rice variety (Jingang 30), is highly resistant to all field Xoo strains tested so far. Although the BB resistance of CBB23 has been widely used in rice breeding programmes, the mechanism of its extremely broad-spectrum resistance remains unknown. Here, we report the molecular cloning of an avirulence gene, designated as avrXa23, from Xoo strain PXO99(A) . We validate that AvrXa23, a novel transcription activator-like effector, specifically triggers the broad-spectrum BB resistance in CBB23. The prevalence of avrXa23 in all 38 Xoo strains surveyed may explain the broad-spectrum feature of BB resistance in CBB23. The results will significantly facilitate the molecular cloning of the corresponding resistance (R) gene in the host, and provide new insights into our understanding of the molecular mechanism for broad-spectrum disease resistance in plants. PMID:24286630

Wang, Chun-Lian; Qin, Teng-Fei; Yu, Hong-Man; Zhang, Xiao-Ping; Che, Jin-Ying; Gao, Ying; Zheng, Chong-Ke; Yang, Bing; Zhao, Kai-Jun

2014-05-01

412

Coenzyme Q10, plasma membrane oxidase and growth control.  

PubMed

The plasma membrane of eukaryotic cells contains an NADH oxidase which can transfer electrons across the membrane. This oxidase is controlled by hormones, growth factors and other ligands which bind to receptors in the plasma membrane. Oncogenes also affect activity of the oxidase. Natural serum components such as diferric transferrin and ceruloplasmin which stimulate proliferation also stimulate membrane oxidase activity. Additional growth factors can be required to complement the proliferative effect. Electron transport across the plasma membrane can be measured by the reduction of impermeable electron acceptors, such as ferricyanide, which also stimulate cell growth. The oxidants activate growth-related signals such as cytosolic alkalinization and calcium mobilization. Antiproliferative agents such as adriamycin and retinoic acid inhibit the plasma membrane electron transport. Flavin, Coenzyme Q and an iron chelate on the cell surface are apparent electron carriers for the transmembrane electron transport. Coenzyme Q10 stimulates cell growth, and Coenzyme Q analogs such as capsaicin and chloroquine reversibly inhibit both growth and transmembrane electron transport. Addition of iron salts to the depleted cells restores activity and growth. The ligand-activated oxidase in the plasma membrane introduces a new basis for control of signal transduction in cells. The redox state of the quinone in the oxidase is proposed to control tyrosine kinase either by generation of H2O2 or redox-induced conformational change. PMID:7752819

Crane, F L; Sun, I L; Crowe, R A; Alcain, F J; Löw, H

1994-01-01

413

Lysyl oxidase activity regulates oncogenic stress response and tumorigenesis  

PubMed Central

Cellular senescence, a stable proliferation arrest, is induced in response to various stresses. Oncogenic stress-induced senescence (OIS) results in blocked proliferation and constitutes a fail-safe program counteracting tumorigenesis. The events that enable a tumor in a benign senescent state to escape from OIS and become malignant are largely unknown. We show that lysyl oxidase activity contributes to the decision to maintain senescence. Indeed, in human epithelial cell the constitutive expression of the LOX or LOXL2 protein favored OIS escape, whereas inhibition of lysyl oxidase activity was found to stabilize OIS. The relevance of these in vitro observations is supported by in vivo findings: in a transgenic mouse model of aggressive pancreatic ductal adenocarcinoma (PDAC), increasing lysyl oxidase activity accelerates senescence escape, whereas inhibition of lysyl oxidase activity was found to stabilize senescence, delay tumorigenesis, and increase survival. Mechanistically, we show that lysyl oxidase activity favors the escape of senescence by regulating the focal-adhesion kinase. Altogether, our results demonstrate that lysyl oxidase activity participates in primary tumor growth by directly impacting the senescence stability. PMID:24113189

Wiel, C; Augert, A; Vincent, D F; Gitenay, D; Vindrieux, D; Le Calve, B; Arfi, V; Lallet-Daher, H; Reynaud, C; Treilleux, I; Bartholin, L; Lelievre, E; Bernard, D

2013-01-01

414

Lysyl oxidase activity regulates oncogenic stress response and tumorigenesis.  

PubMed

Cellular senescence, a stable proliferation arrest, is induced in response to various stresses. Oncogenic stress-induced senescence (OIS) results in blocked proliferation and constitutes a fail-safe program counteracting tumorigenesis. The events that enable a tumor in a benign senescent state to escape from OIS and become malignant are largely unknown. We show that lysyl oxidase activity contributes to the decision to maintain senescence. Indeed, in human epithelial cell the constitutive expression of the LOX or LOXL2 protein favored OIS escape, whereas inhibition of lysyl oxidase activity was found to stabilize OIS. The relevance of these in vitro observations is supported by in vivo findings: in a transgenic mouse model of aggressive pancreatic ductal adenocarcinoma (PDAC), increasing lysyl oxidase activity accelerates senescence escape, whereas inhibition of lysyl oxidase activity was found to stabilize senescence, delay tumorigenesis, and increase survival. Mechanistically, we show that lysyl oxidase activity favors the escape of senescence by regulating the focal-adhesion kinase. Altogether, our results demonstrate that lysyl oxidase activity participates in primary tumor growth by directly impacting the senescence stability. PMID:24113189

Wiel, C; Augert, A; Vincent, D F; Gitenay, D; Vindrieux, D; Le Calvé, B; Arfi, V; Lallet-Daher, H; Reynaud, C; Treilleux, I; Bartholin, L; Lelievre, E; Bernard, D

2013-01-01

415

Evaluation of Water–Nitrogen Schemes for Rice in Iran, Using ORYZA2000 Model  

Microsoft Academic Search

The model ORYZA2000 simulates the growth and development of rice under conditions of potential production and water and nitrogen (N) limitations. Crop simulation models could provide an alternative, less time-consuming, and inexpensive means of determining the optimum crop N and irrigation requirements under varied irrigation and nitrogen conditions. Water productivity (WP) is a concept of partial productivity and denotes the

Ebrahim Amiri; Mojtaba Rezaei

2010-01-01

416

TECHNICAL REPORTS Water quality concerns have arisen related to rice (Oryza sativa  

E-print Network

TECHNICAL REPORTS 304 Water quality concerns have arisen related to rice (Oryza sativa L.) field applications. Water quality concerns have arisen in relation to the potential increase in DOC concentration drain water, which has the potential to contribute large amounts of dissolved organic carbon (DOC

van Kessel, Chris

417

Production of starch-gel digesting amyloglucosidase by Aspergillus oryzae HS3 in solid state fermentation  

Microsoft Academic Search

Aspergillus oryzae HS-3, isolated from local soil, produced very high levels of solid starch-gel digesting amyloglucosidase by solid state fermentation in Erlenmeyer flasks and enamel coated metallic trays. Productivity was affected by the nature of the solid substrate, nature of the moistening agent, level of moisture content, incubation temperature, presence or absence of carbon, nitrogen and mineral supplements. Maximum enzyme

Harpreet Singh; Sanjeev K Soni

2001-01-01

418

Identification of Trait-Improving Quantitative Trait Loci Alleles From a Wild Rice Relative, Oryza rufipogon  

Microsoft Academic Search

Wild species are valued as a unique source of genetic variation, but they have rarely been used for the genetic improvement of quantitative traits. To identify trait-improving quantitative trait loci (QTL) alleles from exotic species, an accession of Oryza rufipogon, a relative of cultivated rice, was chosen on the basis of a genetic diversity study. An interspecific BC2 testcross population

Jinhua Xiao; Jiming Li; Silvana Grandillo; Sang Nag Ahn; Longping Yuan; Steven D. Tanksley; Susan R. McCouch

419

Hydrogen Production by Co-cultures of Rhizopus oryzae and a Photosynthetic Bacterium, Rhodobacter sphaeroides RV  

NASA Astrophysics Data System (ADS)

Hydrogen production with glucose by using co-immobilized cultures of a fungus, Rhizopus oryzae NBRC5384, and a photosynthetic bacterium, Rhodobacter sphaeroides RV, in agar gels was studied. The co-immobilized cultures converted glucose to hydrogen via lactate in a high molar yield of about 8moles of hydrogen per glucose at a maximum under illuminated conditions.

Asada, Yasuo; Ishimi, Katsuhiro; Nagata, Yoko; Wakayama, Tatsuki; Miyake, Jun; Kohno, Hideki

420

Partial diallel analysis of agronomic characters in rice (Oryza sativa L.)  

Microsoft Academic Search

Rice (Oryza sativa L.) breeding seeking to combine high productivity and cold tolerance for the temperate Latin America region is an important challenge. We estimated some useful parameters which can be used to investigate the genetic control of agronomic characters in crosses combining cold tolerance and productivity. A partial diallel de- sign was used in crosses between six tropical indica

Edgar Alonso Torres; Isaias O. Geraldi

2007-01-01

421

Genetic basis of heterosis and inbreeding depression in rice (Oryza sativa L.)  

Microsoft Academic Search

The genetic basis of heterosis was studied through mid-parent, standard variety and better parent for 11 quantitative traits in 17 parental lines and their 10 selected hybrids in rice (Oryza sativa L.). The characters were plant height, days to flag leaf initiation, days to first panicle initiation, days to 100% flowering, panicle length, flag leaf length, days to maturity, number

422

Chronic monoamine oxidase-B inhibitor treatment blocks monoamine oxidase-A enzyme activity.  

PubMed

Patients with Parkinson's disease receive selective irreversible monoamine oxidase (MAO)-B inhibitors, but their effects on MAO-A activity are not known during long-term application. We determined MAO-A inhibition in plasma samples from patients with MAO-B inhibitor intake or without MAO-B inhibitor treatment and from healthy controls. We detected a 70 % reduction of MAO-A activity in patients with MAO-B inhibitor therapy in comparison to the other groups. Our results suggest that treatment with MAO-B inhibitor may also influence MAO-A activity in vivo, when administered daily. PMID:24272680

Bartl, Jasmin; Müller, Thomas; Grünblatt, Edna; Gerlach, Manfred; Riederer, Peter

2014-04-01

423

Purification of enzymatically active human lysyl oxidase and lysyl oxidase-like protein from Escherichia coli inclusion bodies  

Microsoft Academic Search

Lysyl oxidase (LOX) is an extracellular copper dependent enzyme catalyzing lysine-derived cross-links in extracellular matrix proteins. Recent molecular cloning has revealed the existence of a LOX family consisting of LOX and four lysyl oxidase-like proteins (LOXLs; LOXL, LOXL2, LOXL3, and LOXL4). Each member of the LOX family contains a copper-binding domain, residues for lysyl-tyrosyl quinone, and a cytokine receptor-like domain.

Sang Taek Jung; Moon Suk Kim; Ji Yeon Seo; Hyung Chul Kim; Youngho Kim

2003-01-01

424

Study of Drug Metabolism by Xanthine Oxidase  

PubMed Central

In this work, we report the studies of drug metabolism by xanthine oxidase (XOD) with electrochemical techniques. Firstly, a pair of stable, well-defined and quasi-reversible oxidation/reduction peaks is obtained with the formal potential at ?413.1 mV (vs. SCE) after embedding XOD in salmon sperm DNA membrane on the surface of pyrolytic graphite electrode. Then, a new steady peak can be observed at ?730 mV (vs. SCE) upon the addition of 6-mercaptopurine (6-MP) to the electrochemical system, indicating the metabolism of 6-MP by XOD. Furthermore, the chronoamperometric response shows that the current of the catalytic peak located at ?730 mV increases with addition of 6-MP in a concentration-dependent manner, and the increase of the chronoamperometric current can be inhibited by an XOD inhibitor, quercetin. Therefore, our results prove that XOD/DNA modified electrode can be efficiently used to study the metabolism of 6-MP, which may provide a convenient approach for in vitro studies on enzyme-catalyzed drug metabolism. PMID:22606015

Zhao, Jing; He, Xiaolin; Yang, Nana; Sun, Lizhou; Li, Genxi

2012-01-01

425

MONOAMINE OXIDASE: RADIOTRACER DEVELOPMENT AND HUMAN STUDIES.  

SciTech Connect

PET is uniquely capable of providing information on biochemical transformations in the living human body. Although most of the studies of monoamine oxidase (MAO) have focused on measurements in the brain, the role of peripheral MAO as a phase 1 enzyme for the metabolism of drugs and xenobiotics is gaining attention (Strolin Benedetti and Tipton, 1998; Castagnoli et al., 1997.). MAO is well suited for this role because its concentration in organs such as kidneys, liver and digestive organs is high sometimes exceeding that in the brain. Knowledge of the distribution of the MAO subtypes within different organs and different cells is important in determining which substrates (and which drugs and xenobiotics) have access to which MAO subtypes. The highly variable subtype distribution with different species makes human studies even more important. In addition, the deleterious side effects of combining MAO inhibitors with other drugs and with foodstuffs makes it important to know the MAO inhibitory potency of different drugs both in the brain and in peripheral organs (Ulus et al., 2000). Clearly PET can play a role in answering these questions, in drug research and development and in discovering some of the factors which contribute to the highly variable MAO levels in different individuals.

FOWLER,J.S.; LOGAN,J.; VOLKOW,N.D.; WANG,G.J.; MACGREGOR,R.R.; DING,Y.S.

2000-09-28

426

Monoamine oxidase inactivation: from pathophysiology to therapeutics  

PubMed Central

Monoamine oxidases (MAOs) A and B are mitochondrial bound isoenzymes which catalyze the oxidative deamination of dietary amines and monoamine neurotransmitters, such as serotonin, norepinephrine, dopamine, ?-phenylethylamine and other trace amines. The rapid degradation of these molecules ensures the proper functioning of synaptic neurotransmission and is critically important for the regulation of emotional behaviors and other brain functions. The byproducts of MAO-mediated reactions include several chemical species with neurotoxic potential, such as hydrogen peroxide, ammonia and aldehydes. As a consequence, it is widely speculated that prolonged excessive activity of these enzymes may be conducive to mitochondrial damages and neurodegenerative disturbances. In keeping with these premises, the development of MAO inhibitors has led to important breakthroughs in the therapy of several neuropsychiatric disorders, ranging from mood disorders to Parkinson’s disease. Furthermore, the characterization of MAO knockout (KO) mice has revealed that the inactivation of this enzyme produces a number of functional and behavioral alterations, some of which may be harnessed for therapeutic aims. In this article, we discuss the intriguing hypothesis that the attenuation of the oxidative stress induced by the inactivation of either MAO isoform may contribute to both antidepressant and antiparkinsonian actions of MAO inhibitors. This possibility further highlights MAO inactivation as a rich source of novel avenues in the treatment of mental disorders. PMID:18652859

Bortolato, Marco; Chen, Kevin; Shih, Jean C

2008-01-01

427

Alzheimer disease ?-amyloid activity mimics cholesterol oxidase  

PubMed Central

The abnormal accumulation of amyloid ?-peptide (A?) in the form of senile (or amyloid) plaques is one of the main characteristics of Alzheimer disease (AD). Both cholesterol and Cu2+ have been implicated in AD pathogenesis and plaque formation. A? binds Cu2+ with very high affinity, forming a redox-active complex that catalyzes H2O2 production from O2 and cholesterol. Here we show that A?:Cu2+ complexes oxidize cholesterol selectively at the C-3 hydroxyl group, catalytically producing 4-cholesten-3-one and therefore mimicking the activity of cholesterol oxidase, which is implicated in cardiovascular disease. A? toxicity in neuronal cultures correlated with this activity, which was inhibited by Cu2+ chelators including clioquinol. Cell death induced by staurosporine or H2O2 did not elevate 4-cholesten-3-one levels. Brain tissue from AD subjects had 98% more 4-cholesten-3-one than tissue from age-matched control subjects. We observed a similar increase in the brains of Tg2576 transgenic mice compared with nontransgenic littermates; the increase was inhibited by in vivo treatment with clioquinol, which suggests that brain A? accumulation elevates 4-cholesten-3-one levels in AD. Cu2+-mediated oxidation of cholesterol may be a pathogenic mechanism common to atherosclerosis and AD. PMID:16127459

Puglielli, Luigi; Friedlich, Avi L.; Setchell, Kenneth D.R.; Nagano, Seiichi; Opazo, Carlos; Cherny, Robert A.; Barnham, Kevin J.; Wade, John D.; Melov, Simon; Kovacs, Dora M.; Bush, Ashley I.

2005-01-01

428

Molecular Analysis of an Inactive Aflatoxin Biosynthesis Gene Cluster in Aspergillus oryzae RIB Strains†  

PubMed Central

To help assess the potential for aflatoxin production by Aspergillus oryzae, the structure of an aflatoxin biosynthesis gene homolog cluster in A. oryzae RIB 40 was analyzed. Although most genes in the corresponding cluster exhibited from 97 to 99% similarity to those of Aspergillus flavus, three genes shared 93% similarity or less. A 257-bp deletion in the aflT region, a frameshift mutation in norA, and a base pair substitution in verA were found in A. oryzae RIB 40. In the aflR promoter, two substitutions were found in one of the three putative AreA binding sites and in the FacB binding site. PCR primers were designed to amplify homologs of aflT, nor-1, aflR, norA, avnA, verB, and vbs and were used to detect these genes in 210 A. oryzae strains. Based on the PCR results, the A. oryzae RIB strains were classified into three groups, although most of them fell into two of the groups. Group 1, in which amplification of all seven genes was confirmed, contained 122 RIB strains (58.1% of examined strains), including RIB 40. Seventy-seven strains (36.7%) belonged to group 2, characterized by having only vbs, verB, and avnA in half of the cluster. Although slight expression of aflR was detected by reverse transcription-PCR in some group 1 strains, including RIB 40, other genes (avnA, vbs, verB, and omtA) related to aflatoxin production were not detected. aflR was not detected in group 2 strains by Southern analysis. PMID:16391082

Tominaga, Mihoko; Lee, Yun-Hae; Hayashi, Risa; Suzuki, Yuji; Yamada, Osamu; Sakamoto, Kazutoshi; Gotoh, Kuniyasu; Akita, Osamu

2006-01-01

429

Genome Information of Methylobacterium oryzae, a Plant-Probiotic Methylotroph in the Phyllosphere  

PubMed Central

Pink-pigmented facultative methylotrophs in the Rhizobiales are widespread in the environment, and many Methylobacterium species associated with plants produce plant growth-promoting substances. To gain insights into the life style at the phyllosphere and the genetic bases of plant growth promotion, we determined and analyzed the complete genome sequence of Methylobacterium oryzae CBMB20T, a strain isolated from rice stem. The genome consists of a 6.29-Mb chromosome and four plasmids, designated as pMOC1 to pMOC4. Among the 6,274 coding sequences in the chromosome, the bacterium has, besides most of the genes for the central metabolism, all of the essential genes for the assimilation and dissimilation of methanol that are either located in methylotrophy islands or dispersed. M. oryzae is equipped with several kinds of genes for adaptation to plant surfaces such as defense against UV radiation, oxidative stress, desiccation, or nutrient deficiency, as well as high proportion of genes related to motility and signaling. Moreover, it has an array of genes involved in metabolic pathways that may contribute to promotion of plant growth; they include auxin biosynthesis, cytokine biosynthesis, vitamin B12 biosynthesis, urea metabolism, biosorption of heavy metals or decrease of metal toxicity, pyrroloquinoline quinone biosynthesis, 1-aminocyclopropane-1-carboxylate deamination, phosphate solubilization, and thiosulfate oxidation. Through the genome analysis of M. oryzae, we provide information on the full gene complement of M. oryzae that resides in the aerial parts of plants and enhances plant growth. The plant-associated lifestyle of M. oryzae pertaining to methylotrophy and plant growth promotion, and its potential as a candidate for a bioinoculant targeted to the phyllosphere and focused on phytostimulation are illuminated. PMID:25211235

Madhaiyan, Munusamy; Lee, Yi; Sa, Tong-Min; Oh, Tae Kwang; Kim, Jihyun F.

2014-01-01

430

Genomic Analysis of the Basal Lineage Fungus Rhizopus oryzae Reveals a Whole-Genome Duplication  

PubMed Central

Rhizopus oryzae is the primary cause of mucormycosis, an emerging, life-threatening infection characterized by rapid angioinvasive growth with an overall mortality rate that exceeds 50%. As a representative of the paraphyletic basal group of the fungal kingdom called “zygomycetes,” R. oryzae is also used as a model to study fungal evolution. Here we report the genome sequence of R. oryzae strain 99–880, isolated from a fatal case of mucormycosis. The highly repetitive 45.3 Mb genome assembly contains abundant transposable elements (TEs), comprising approximately 20% of the genome. We predicted 13,895 protein-coding genes not overlapping TEs, many of which are paralogous gene pairs. The order and genomic arrangement of the duplicated gene pairs and their common phylogenetic origin provide evidence for an ancestral whole-genome duplication (WGD) event. The WGD resulted in the duplication of nearly all subunits of the protein complexes associated with respiratory electron transport chains, the V-ATPase, and the ubiquitin–proteasome systems. The WGD, together with recent gene duplications, resulted in the expansion of multiple gene families related to cell growth and signal transduction, as well as secreted aspartic protease and subtilase protein families, which are known fungal virulence factors. The duplication of the ergosterol biosynthetic pathway, especially the major azole target, lanosterol 14?-demethylase (ERG11), could contribute to the variable responses of R. oryzae to different azole drugs, including voriconazole and posaconazole. Expanded families of cell-wall synthesis enzymes, essential for fungal cell integrity but absent in mammalian hosts, reveal potential targets for novel and R. oryzae-specific diagnostic and therapeutic treatments. PMID:19578406

Ma, Li-Jun; Ibrahim, Ashraf S.; Skory, Christopher; Grabherr, Manfred G.; Burger, Gertraud; Butler, Margi; Elias, Marek; Idnurm, Alexander; Lang, B. Franz; Sone, Teruo; Abe, Ayumi; Calvo, Sarah E.; Corrochano, Luis M.; Engels, Reinhard; Fu, Jianmin; Hansberg, Wilhelm; Kim, Jung-Mi; Kodira, Chinnappa D.; Koehrsen, Michael J.; Liu, Bo; Miranda-Saavedra, Diego; O'Leary, Sinead; Ortiz-Castellanos, Lucila; Poulter, Russell; Rodriguez-Romero, Julio; Ruiz-Herrera, Jose; Shen, Yao-Qing; Zeng, Qiandong; Galagan, James; Birren, Bruce W.

2009-01-01

431

High activity catechol 1,2-dioxygenase from Stenotrophomonas maltophilia strain KB2 as a useful tool in cis,cis-muconic acid production.  

PubMed

This is the first report of a catechol 1,2-dioxygenase from Stenotrophomonas maltophilia strain KB2 with high activity against catechol and its methyl derivatives. This enzyme was maximally active at pH 8.0 and 40 °C and the half-life of the enzyme at this temperature was 3 h. Kinetic studies showed that the value of K m and V max was 12.8 ?M and 1,218.8 U/mg of protein, respectively. During our studies on kinetic properties of the catechol 1,2-dioxygenase we observed substrate inhibition at >80 ?M. The nucleotide sequence of the gene encoding the S. maltophilia strain KB2 catechol 1,2-dioxygenase has high identity with other catA genes from members of the genus Pseudomonas. The deduced 314-residue sequence of the enzyme corresponds to a protein of molecular mass 34.5 kDa. This enzyme was inhibited by competitive inhibitors (phenol derivatives) only by ca. 30 %. High tolerance against condition changes is desirable in industrial processes. Our data suggest that this enzyme could be of use as a tool in production of cis,cis-muconic acid and its derivatives. PMID:23536173

Guzik, Urszula; Hupert-Kocurek, Katarzyna; Sitnik, Ma?gorzata; Wojcieszy?ska, Danuta

2013-06-01

432

Influence of Chemical Kinetics on Postcolumn Reaction in a Capillary Taylor Reactor with Catechol Analytes and Photoluminescence Following Electron Transfer  

PubMed Central

Postcolumn derivatization reactions can enhance detector sensitivity and selectivity, but their successful combination with capillary liquid chromatography has been limited because of the small peak volumes in capillary chromatography. A capillary Taylor reactor (CTR), developed in our laboratory, provides simple and effective mixing and reaction in a 25-?m-radius postcolumn capillary. Homogenization of reactant streams occurs by radial diffusion, and a chemical reaction follows. Three characteristic times for a given reaction process can be predicted using simple physical and chemical parameters. Two of these times are the homogenization time, which governs how long it takes the molecules in the analyte and reagent streams to mix, and the reaction time, which governs how long the molecules in a homogeneous solution take to react. The third characteristic time is an adjustment to the reaction time called the start time, which represents an estimate of the average time the analyte stream spends without exposure to reagent. In this study, laser-induced fluorescence monitored the extent of the postcolumn reaction (reduction of Os(bpy)33+ by analyte to the photoluminescent Os(bpy)32+) in a CTR. The reaction time depends on the reaction rates. Analysis of product versus time data yielded second-order reaction rate constants between the PFET reagent, tris(2,2?-bipyridine)osmium, and standards ((ferrocenylmethyl)trimethylammonium cation and p-hydroquinone) or catechols (dopamine, epinephrine, norepinephrine, 3, 4-dihydroxyphenylacetic acid. The extent of the reactions in a CTR were then predicted from initial reaction conditions and compared to experimental results. Both the theory and experimental results suggested the reactions of catechols were generally kinetically controlled, while those of the standards were controlled by mixing time (1–2 s). Thus, the extent of homogenization can be monitored in a CTR using the relatively fast reaction of the reagent and p-hydroquinone. Kinetically controlled reactions of catechols, however, could be also completed in a reasonable time at increased reagent concentration. A satisfactory reactor, operating at 1.7 cm/s (2 ?L/min) velocity with solutes having diffusion coefficients in the 5 × 10?6 cm2/s range, can be constructed from 8.0 cm of 25-?m-radius capillary. Slower reactions require longer reaction times, but theoretical calculations expect that a CTR does not broaden a chromatographic peak (N = 14 000) from a 100-?m-capillary chromatography column by 10% if the pseudo-first-order rate constant is larger than 0.1 s?1. PMID:15858975

Jung, Moon Chul; Weber, Stephen G.

2006-01-01

433

Purification and characterization of protocatechuate 2,3-dioxygenase from Bacillus macerans: a new extradiol catecholic dioxygenase.  

PubMed Central

Protocatechuate 2,3-dioxygenase (2,3-PCD) from Bacillus macerans JJ1b has been purified to homogeneity for the first time. The enzyme catalyzes proximal extradiol ring cleavage of protocatechuate (PCA) with the attendant incorporation of both atoms of oxygen from O2. The holoenzyme has a mass of 143 +/- 7 kDa as determined by ultracentrifugation and other techniques. It is composed of four apparently identical