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1

Crystallization and preliminary X-ray analysis of Aspergillus oryzae catechol oxidase.  

PubMed

Catechol oxidase is an enzyme that catalyzes the oxidation of o-diphenols to the corresponding o-quinones. It is a copper-containing enzyme with a binuclear copper active site. Here, the crystallization and multiple-wavelength anomalous dispersion data collection of catechol oxidase from the mould fungus Aspergillus oryzae are described. During the purification, three forms of the enzyme (39.3, 40.5 and 44.3?kDa) were obtained. A mixture of these three forms was initially crystallized and gave crystals that diffracted to 2.5?Ĺ resolution and belonged to space group P3(2)21, with unit-cell parameters a = b = 118.9, c = 84.5?Ĺ, ? = ? = 90, ? = 120°. A preparation containing only the shorter form (39.3?kDa) produced crystals that diffracted to 2.9?Ĺ resolution and belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 51.8, b = 95.3, c = 139.5?Ĺ, ? = ? = ? = 90°. PMID:21636908

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

2011-06-01

2

Crystallization and preliminary X-ray analysis of Aspergillus oryzae catechol oxidase  

PubMed Central

Catechol oxidase is an enzyme that catalyzes the oxidation of o-diphenols to the corresponding o-quinones. It is a copper-containing enzyme with a binuclear copper active site. Here, the crystallization and multiple-wavelength anomalous dispersion data collection of catechol oxidase from the mould fungus Aspergillus oryzae are described. During the purification, three forms of the enzyme (39.3, 40.5 and 44.3?kDa) were obtained. A mixture of these three forms was initially crystallized and gave crystals that diffracted to 2.5?Ĺ resolution and belonged to space group P3221, with unit-cell parameters a = b = 118.9, c = 84.5?Ĺ, ? = ? = 90, ? = 120°. A preparation containing only the shorter form (39.3?kDa) produced crystals that diffracted to 2.9?Ĺ resolution and belonged to space group P212121, with unit-cell parameters a = 51.8, b = 95.3, c = 139.5?Ĺ, ? = ? = ? = 90°.

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

2011-01-01

3

Amperometric catechol biosensor based on polyaniline–polyphenol oxidase  

Microsoft Academic Search

A novel catechol biosensor was described based on the immobilization of polyphenol oxidase (PPO) into polyaniline (PANI), which was easily constructed by direct electropolymerization of aniline in a solution containing ionic liquid, 1-ethyl-3-methylimidazolium ethyl sulfate (EMIES). The developed biosensor for the detection of catechol has a linear range of 1.25–150?moldm?3. The maximum response current (Imax) and the Michaelis–Menten constant (k?m)

Yongyan Tan; Xiaoxia Guo; Jinghui Zhang; Jinqing Kan

2010-01-01

4

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

PubMed

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

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

2012-09-01

5

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

6

Quaternary ammonium functionalized clay film electrodes modified with polyphenol oxidase for the sensitive detection of catechol.  

PubMed

Naturally occurring Cameroonian smectite clay has been grafted with trimethylpropylammonium (TMPA) groups and the resulting organoclay has been deposited onto a glassy carbon electrode surface as a suitable immobilization matrix for polyphenol oxidase (PPO). High sensitivity of the electrochemical device to catechol biosensing can be achieved when the enzyme was impregnated within the organoclay film subsequent to its deposition due to favorable electrostatic interaction between PPO and the TMPA-clay layer. The bioelectrode preparation method was also compatible with the use of a mediator (i.e., ferrocene) and the best performance was obtained with a three-layer configuration made of glassy carbon coated with a first layer of ferrocene (Fc), which was then covered with the PPO-impregnated TMPA-clay layer, and finally overcoated with an enzyme-free TMPA-clay film acting as a protecting overlayer to avoid leaching of the biomolecule in solution. The electrochemical behavior of the modified film electrodes was first characterized by cyclic voltammetry and, then, they were evaluated for the amperometric biosensing of the model analyte catechol in batch conditions and in flow injection analysis. Various experimental parameters likely to influence the biosensor response have been investigated, including the electrode preparation mode (composition configuration, thickness), the usefulness of a mediator, the operating potential and pH of the medium, as well as the advantageous features of the TMPA-clay in comparison to related film electrodes based on non-functionalized clays. The organoclay was found to provide a favorable environment to enzyme activity and the multilayer configuration of the film electrode to provide a biosensor with good characteristics, such as an extended linear range for catechol detection (2 x 10(-8) to 1.2 x 10(-5)M) and a detection limit in the nanomolar range (9 x 10(-9)M). PMID:17537626

Mbouguen, Justin Kemmegne; Ngameni, Emmanuel; Walcarius, Alain

2007-09-30

7

Investigation of a correlation between monoamine oxidase B and catechol- O-methyltransferase activity in human blood cells  

Microsoft Academic Search

Monoamine oxidase B (MAO-B) and catechol-O-methyltransferase (COMT) are pivotal enzymes in the catabolism of several neurotransmitters. MAO-B and COMT activity can be reliably measured in human platelets and erythrocytes, respectively. This study investigated whether a correlation exists between the activity of the two enzymes in a panel of 47 elderly subjects (age range 55–80 years). No correlation was apparent between

Jasper Dingemanse; Gerhard Zürcher; Rolf Kettler

2000-01-01

8

Multipart copolyelectrolyte adhesive of the sandcastle worm, Phragmatopoma californica (Fewkes): catechol oxidase catalyzed curing through peptidyl-DOPA.  

PubMed

Tube-building sabellariid polychaetes have major impacts on the geology and ecology of shorelines worldwide. Sandcastle worms, Phragmatopoma californica (Fewkes), live along the western coast of North America. Individual sabellariid worms build tubular shells by gluing together mineral particles with a multipart polyelectrolytic adhesive. Distinct sets of oppositely charged components are packaged and stored in concentrated granules in separate cell types. Homogeneous granules contain sulfated macromolecules as counter-polyanion to polycationic Pc2 and Pc5 proteins, which become major components of the fully cured glue. Heterogeneous granules contain polyphosphoproteins, Pc3A/B, paired with divalent cations and polycationic Pc1 and Pc4 proteins. Both types of granules contain catechol oxidase that catalyzes oxidative cross-linking of L-DOPA. Co-secretion of catechol oxidase guarantees rapid and spatially homogeneous curing with limited mixing of the preassembled adhesive packets. Catechol oxidase remains active long after the glue is fully cured, perhaps providing an active cue for conspecific larval settlement. PMID:23530959

Wang, Ching Shuen; Stewart, Russell J

2013-05-13

9

Changes in Catechol Oxidase and Permeability to Water in Seed Coats of Pisum elatius during Seed Development and Maturation  

PubMed Central

In the developing seed coat of Pisum elatius, o-dihydroxyphenols are present in appreciable amounts at all stages of development. However, catechol oxidase activity rises sharply during the later stages of development, shows a further abrupt rise during dehydration of the seed coat, and then decreases. It is suggested that a tanning reaction is induced by the contact of enzyme with its substrate while cell membranes are ruptured, and that this reaction renders the seed coats impermeable. The entire chain of events does not occur in Pisum sativum which has permeable seed coats.

Marbach, Irith; Mayer, Alfred M.

1975-01-01

10

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

NASA Astrophysics Data System (ADS)

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

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

2005-10-01

11

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

PubMed

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 (k[loss]) and the rate of uptake of 6-[81F]L-DOPA (Ki) in the striatum of normal cynomolgus monkeys. The monkeys received 6-[18F]L-DOPA scans, untreated or after pretreatment with either the peripheral catechol-O-methyltransferase inhibitor nitecapone; the peripheral and central catechol-O-methyltransferase inhibitor tolcapone; the monoamine oxidase inhibitors deprenyl or pargyline; a combination of tolcapone and the monoamine oxidase inhibitors. Tolcapone alone or combined with the monoamine oxidase inhibitors produced a significant decrease in the dopamine turnover (55 to 65%). Neither nitecapone nor monoamine oxidase inhibition alone produced significant changes. These results may have implications for the use of central catechol-O-methyltransferase inhibitors added to routine levodopa therapy in parkinsonian patients. PMID:9346324

Doudet, D J; Chan, G L; Holden, J E; Pate, B D; Morrison, K S; Calne, D B; Ruth, T J

1997-09-01

12

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.  

PubMed

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 different pH behavior using catechol as substrate. Atomic absorption spectrosopic analysis found 1.5 copper atoms per protein molecule. Using EPR spectroscopy we determined 1.8 Cu per molecule catechol oxidase. Furthermore, EPR spectroscopy demonstrated that catechol oxidase is a copper enzyme of type 3. The lack of an EPR signal is due to strong antiferromagnetic coupling that requires a bridging ligand between the two copper ions in the met preparation. Addition to H2O2 to both enzymes leads to oxy catechol oxidase. In the UV/Vis spectrum two new absorption bands occur at 345 nm and 580 nm. In accordance with the oxy forms of hemocyanin and tyrosinase the absorption band at 345 nm is due to an O2(2-) (pi sigma *)-->Cu(II) (dx2 - y2) charge transfer (CT) transition. The absorption band at 580 nm corresponds to the second O2(2)- (pi v*)-->Cu(II) (dx2 - y2) CT transition. The UV/Vis bands in combination with the resonance Raman spectra of oxy catechol oxidase indicate a mu-eta 2:eta 2 binding mode for dioxygen. The intense resonance Raman peak at 277 cm-1, belonging to a Cu-N (axial His) stretching mode, suggests that catechol oxidase has six terminal His ligands, as known for molluscan and arthropodan hemocyanin. PMID:10499103

Rompel, A; Fischer, H; Meiwes, D; Büldt-Karentzopoulos, K; Dillinger, R; Tuczek, F; Witzel, H; Krebs, B

1999-02-01

13

Oryza  

Microsoft Academic Search

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

Darshan S. Brar; Kuldeep Singh

14

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.

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

2013-01-01

15

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

PubMed

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

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

2011-05-01

16

Functional and molecular characterization of plastid terminal oxidase from rice (Oryza sativa).  

PubMed

The plastid terminal oxidase (PTOX) is a plastohydroquinone:oxygen oxidoreductase that shares structural similarities with alternative oxidases (AOX). Multiple roles have been attributed to PTOX, such as involvement in carotene desaturation, a safety valve function, participation in the processes of chlororespiration and setting the redox poise for cyclic electron transport. We have investigated a homogenously pure MBP fusion of PTOX. The protein forms a homo-tetrameric complex containing 2 Fe per monomer and is very specific for the plastoquinone head-group. The reaction kinetics were investigated in a soluble monophasic system using chemically reduced decyl-plastoquinone (DPQ) as the model substrate and, in addition, in a biphasic (liposomal) system in which DPQ was reduced with DT-diaphorase. While PTOX did not detectably produce reactive oxygen species in the monophasic system, their formation was observed by room temperature EPR in the biphasic system in a [DPQH2] and pH-dependent manner. This is probably the result of the higher concentration of DPQ achieved within the partial volume of the lipid bilayer and a higher Km observed with PTOX-membrane associates which is ?47mM compared to the monophasic system where a Km of ?74?M was determined. With liposomes and at the basic stromal pH of photosynthetically active chloroplasts, PTOX was antioxidant at low [DPQH2] gaining prooxidant properties with increasing quinol concentrations. It is concluded that in vivo, PTOX can act as a safety valve when the steady state [PQH2] is low while a certain amount of ROS is formed at high light intensities. PMID:24780313

Yu, Qiuju; Feilke, Kathleen; Krieger-Liszkay, Anja; Beyer, Peter

2014-08-01

17

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

18

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

19

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

20

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

21

Comparative Study of Substrates and Inhibitors of Azospirillum lipoferum and Pyricularia oryzae Laccases  

PubMed Central

Azospirillum lipoferum and Pyricularia oryzae laccases were compared, using several substrates and inhibitors. Sixteen phenolic or nonphenolic compounds were found to be substrates of both fungal and bacterial laccases. In the presence of different phenol oxidase inhibitors, P. oryzae and A. lipoferum laccase activities had similar properties.

Faure, D.; Bouillant, M.; Bally, R.

1995-01-01

22

Catechol O -methyltransferase in vitiligo  

Microsoft Academic Search

Catechol-O-methyltransferase (COMT) is involved in the metabolism of neurotransmitters such as epinephrine, norepinephrine and dopamine. For melanocytes, the enzyme is of particular importance in preventing the formation of toxic o-quinones during melanin synthesis. It has been suggested that COMT plays a regulatory role in melanin synthesis. Indeed, when the melanin precursor molecule DHI(2C) is methylated by COMT it is no

I. C. Le Poole; R. M. J. G. J. van den Wijngaard; N. P. M. Smit; J. Oosting; W. Westerhof; S. Pavel

1994-01-01

23

Crystal structure of catechol O-methyltransferase  

Microsoft Academic Search

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 catechols1-4. 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

Jukka Vidgren; L. Anders Svensson; Anders Liljas

1994-01-01

24

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

25

Properties of Polyphenol Oxidase Extracted from Zhonghuashoutao Peach Flesh  

Microsoft Academic Search

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

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

26

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

27

Identification of the active-site peptide of 2,3-dihydroxybenzoic acid decarboxylase from Aspergillus oryzae  

Microsoft Academic Search

The non-oxidative decarboxylation of aromatic acids is a poorly understood reaction. The transformation of 2,3-dihydroxybenzoic acid to catechol in the fungal metabolism of indole is a prototype of such a reaction. 2,3-Dihydroxybenzoic acid decarboxylase (EC 4.1.1.46) which catalyzes this reaction was purified to homogeneity from anthranilate induced cultures of Aspergillus oryzae using affinity chromatography. The enzyme did not require cofactors

R. Santha; N. Appaji Rao; C. S. Vaidyanathan

1996-01-01

28

Catecholate Siderophores Protect Bacteria from Pyochelin Toxicity  

PubMed Central

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

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

2012-01-01

29

Initiation of Breast Cancer: Activated Catechol Estrogens.  

National Technical Information Service (NTIS)

Determination of the levels of catechol estrogens (CE) in breast tissue constitutes important evidence for the hypothesis that human breast cancer and certain other cancers are initiated by activation of CE to CE-3,4- quinones (CE-3,4-Q), which form depur...

E. G. Rogan

1999-01-01

30

Initiation of Breast Cancer: Activated Catechol Estrogens.  

National Technical Information Service (NTIS)

Determination of the levels of catechol estrogens (CE) in breast tissue constitutes important evidence for the hypothesis that human breast cancer and certain other cancers are initiated by activation of CE to CE-3,4-quinones (CE-3,4-Q), which form depuri...

E. G. Rogan

1998-01-01

31

Oxidase Test Protocol  

NSDL National Science Digital Library

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

American Society For Microbiology;

2010-11-11

32

A novel copper-containing protein from spinach: a blue oxidase with unique properties.  

PubMed

A copper-containing protein resembling in its optical and EPR spectra stellacyanin from latex was isolated from spinach leaves. The protein oxidizes ferrocyanide and catechol. The activity was highest at acidic pH. It was shown that similar proteins isolated from cucumber and squash also possess the oxidase activity to ferrocyanide. PMID:6317078

Sarkissian, L K; Nalbandyan, R M

1983-10-01

33

Urinary excretion of catechol amines in the rat after their liberation by reserpine or dexamphetamine  

PubMed Central

Daily urinary excretion of catechol amines in normal rats and in rats from which the adrenal medullae had been removed has been determined by a photofluorimetric method. In both groups, reserpine (2 mg/kg, intraperitoneally) produces: (1) A decrease in the urinary excretion of noradrenaline which persists for more than 3 weeks; this action is not influenced by monoamine oxidase inhibitors and mecamylamine. (2) An increase, within 20 to 68 hr, in the urinary excretion of adrenaline, even though the urine of rats without adrenal medullae does not usually contain adrenaline. These effects are prevented by monoamine oxidase inhibitors and, in the normal animals, are reduced by mecamylamine. In both groups, dexamphetamine (6 mg/kg, intraperitoneally) produces an increase in the excretion of adrenaline and noradrenaline, the adrenaline appearing in the urine of the rats without adrenal medullae within 20 to 44 hr. Mecamylamine prevents the effect of dexamphetamine on the excretion of noradrenaline. Dexamphetamine, administered within a week of reserpine treatment, produces its usual effects on the urinary excretion of catechol amines in normal rats, but has no effect in rats without adrenal medullae. The results are discussed with regard to both the mechanism by which reserpine and dexamphetamine influence the peripheral stores of adrenaline and noradrenaline, and the significance of the adrenal and extra-adrenal chromaffin system.

Biscardi, A. M.; Carpi, A.; Orsingher, O. A.

1964-01-01

34

Nitroderivatives of catechol: from synthesis to application.  

PubMed

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

Gavazov, Kiril B

2012-03-01

35

Versatile nanostructured materials via direct reaction of functionalized catechols.  

PubMed

A facile one-step polymerization strategy is explored to achieve novel catechol-based materials. Depending on the functionality of the catechol, the as-prepared product can be used to modify at will the surface tension of nano and bulk structures, from oleo-/hydrophobic to highly hydrophilic. A hydrophobic catechol prepared thus polymerized shows the ability to self-assemble as solid nanoparticles with sticky properties in polar solvent media. Such a versatile concept is ideal for the development of catechol-based multifunctional materials. PMID:23418006

Saiz-Poseu, Javier; Sedó, Josep; García, Beatriz; Benaiges, Cristina; Parella, Teo; Alibés, Ramon; Hernando, Jordi; Busqué, Felix; Ruiz-Molina, Daniel

2013-04-11

36

Low catechol-O-methyltransferase activity in a Saami population  

Microsoft Academic Search

Catechol-O-methyltransferase (COMT) catalyzes the O-methylation of catechol hormones, neurotransmitters and certain drugs. It is subject to genetic polymorphism and ethnic differences. High red blood cell (RBC) COMT activity has been correlated with a poor response to levodopa treatment in Parkinson's disease. RBC COMT was determined in a Norwegian population (n=213) of whom 115 were Saami (Lapps).

B. Klemetsdal; B. Straume; T. Giverhaug; J. Aarbakke

1994-01-01

37

Purification and characterization of Ocimum basilicum L. polyphenol oxidase.  

PubMed

A partial characterization of polyphenol oxidase (PPO) activity in Ocimum basilicum L. is described. PPO in O. basilicum L. was extracted and purified through (NH4)2SO4 precipitation, dialysis, and a Sepharose 4B-l-tyrosine-p-aminobenzoic acid affinity column. The samples obtained from (NH4)2SO4 precipitation and dialysis were used for the characterization of PPO. At the end of purification by affinity chromatography, 11.5-fold purification was achived. The purified enzyme exhibited a clear single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The molecular mass of the enzyme was estimated to be approximately 54 kDa. The contents of total phenolic and protein of O. basilicum L. extracts were determined. The total phenolic content of O. basilicum L. was determined spectrophotometrically according to the Folin-Ciocalteu procedure and was found to be 280 mg 100 g(-1) on a fresh weight basis. The protein content was determined according to the Bradford method. The enzyme showed activity to 4-methylcatechol, catechol, and pyrogallol substrates, but not to tyrosine. Therefore, of these three substrates, 4-methylcatecol was the best substrate due to the highest V(max)/K(m) value, followed by pyrogallol and catechol. The optimum pH was at 6, 8, and 9 for 4-methylcatechol, catechol, and pyrogallol, respectively. The enzyme had an optimum temperature of 20, 40, and 50 degrees C for 4-methylcatechol, catechol, and pyrogallol, respectively. It was found that optimum temperature and pH were dependent on the substrates studied. The enzyme activity with increasing temperature and inactivation time for 4-methylcatechol, catechol, and pyrogallol substrates decreased due to heat denaturation of the enzyme. PMID:16366719

Dogan, Serap; Turan, Pinar; Dogan, Mehmet; Arslan, Oktay; Alkan, Mahir

2005-12-28

38

Bioinspired catecholic copolymers for antifouling surface coatings.  

PubMed

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

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

2013-05-01

39

Secretory expression of the non-secretory-type Lentinula edodes laccase by Aspergillus oryzae.  

PubMed

The shiitake mushroom, Lentinula edodes, has an extracelluar secretory-type laccase, Lcc1, and a fruiting-body-accumulation-type laccase, Lcc4. We previously reported the production of Lcc1 by plant cells, but had difficulty producing Lcc4. Here, we report the production of Lcc1 and Lcc4 by Aspergillus oryzae and the extracellular secretory production of Lcc4 using a modified secretion signal peptide (SP) from Lcc1. Sp-Lcc4 produced by A. oryzae had biochemical activities similar to Lcc4 produced by L. edodes. Lcc1 did not react with beta-(3,4-dihydroxyphenol) alanine (DOPA), but Lcc4 from L. edodes and A. oryzae could oxidize DOPA. K(M) values for the substrates 2,2'-azino-di-(3-ethylbenzthiazolinsulfonate), 2,6-dimethoxyphenol, guaiacol, pyrogallol, and catechol were similar for Lcc4 and Sp-Lcc4. In conclusion, a non-secretory-type fungal laccase is secreted into the culture media with its original enzymatic properties by exploiting modified secretory signal peptide. PMID:19230633

Yano, Akira; Kikuchi, Sayaka; Nakagawa, Yuko; Sakamoto, Yuichi; Sato, Toshitsugu

2009-01-01

40

Dietary Catechols and their Relationship to Microbial Endocrinology  

Microsoft Academic Search

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

Neil Shearer; Nicholas J. Walton

41

Catechol-O-methyltransferase and breast cancer risk  

Microsoft Academic Search

Recent studies suggest that a polymorphism in catechol-O- methyltransferase (COMT) is associated with increased risk of breast cancer. Methylation by COMT is the principal pathway for inactivation of catechol estrogens, which are hypothesized to participate in estrogen-induced carcino- genesis. We examined the association of COMT genotype and breast cancer risk in a population-based, case-control study of invasive breast cancer in

Robert C. Millikan; Gary S. Pittman; Chiu-Kit J. Tse; Eric Duell; Beth Newman; David Savitz; Patricia G. Moorman; Robert J. Boissy; Douglas A. Bell

1998-01-01

42

Catechol O -methyltransferase (COMT) genetic polymorphism in a Turkish population  

Microsoft Academic Search

Catechol O-methyltransferase (COMT) inactivates neurotransmitters, catechol hormones and drugs such as levodopa and methyldopa. A low activity allele has been demonstrated at codon 108\\/158 of the soluble and membrane-bound COMT, respectively, whereby a G to A transition results in a valine to methionine substitution. Ethnic and inter-individual differences in red blood cell COMT activity have been observed in the different

Neslihan Kocaba?; Ali Karakaya; Suzanne Cholerton; ?emra ?arda?

2001-01-01

43

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

Microsoft Academic Search

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

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

2011-01-01

44

Surfactant degradation by a catechol-driven Fenton reaction.  

PubMed

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

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

2010-06-15

45

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

46

Diversity of centromeric repeats in two closely related wild rice species, Oryza officinalis and Oryza rhizomatis  

Microsoft Academic Search

Oryza officinalis (CC, 2n=24) and Oryza rhizomatis (CC, 2n=24) belong to the Oryza genus, which contains more than 20 identified wild rice species. Although much has been known about the molecular composition\\u000a and organization of centromeres in Oryza sativa, relatively little is known of its wild relatives. In the present study, we isolated and characterized a 126-bp centromeric\\u000a satellite (CentO-C)

Weidong Bao; Wenli Zhang; Qiuying Yang; Yu Zhang; Bin Han; Minghong Gu; Yongbiao Xue; Zhukuan Cheng

2006-01-01

47

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.

Diamond, Richard D.; Clark, Robert A.

1982-01-01

48

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

49

Oxidases and related redox systems  

SciTech Connect

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

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

1988-01-01

50

Biochemical and Molecular Modeling Studies of the O Methylation of Various Endogenous and Exogenous Catechol Substrates Catalyzed by Recombinant Human Soluble and Membrane-Bound Catechol O -Methyltransferases †  

Microsoft Academic Search

Catechol-O-methyltransferase (COMT, EC 2.1.1.6) catalyzes the O-methylation of a wide array of catechol-containing substrates using S-adenosyl-L-methionine as the methyl donor. In the present study, we have cloned and expressed the human soluble and membrane-bound COMTs (S-COMT and MB- COMT, respectively) in Escherichia coli and have studied their biochemical characteristics for the O-methylation of representative classes of endogenous catechol substrates (catecholamines

Hyoung-Woo Bai; Joong-Youn Shim; Jina Yu; Bao Ting Zhu

2007-01-01

51

Plant catechols prevent lipid peroxidation in human plasma and erythrocytes  

Microsoft Academic Search

The antioxidant activity of several plant catechol derivatives was tested in buffer, plasma, and human erythrocytes. In buffer, chlorogenic acid (CGA), caffeic acid (CA), and dihydrocaffeic acid (DCA) reduced ferric iron equally well in the ferric reducing antioxidant power (FRAP) assay. Low concentrations of the polyphenols enhanced the ability of plasma to reduce ferric iron by about 10%. In plasma,

Jaclyn M. Lekse; Li Xia; Jeffrey Stark; Jason D. Morrow; James M. May

2001-01-01

52

DEPIGMENTATION FROM 4TERTIARY BUTYL CATECHOL-AN EXPERIMENTAL STUDY  

Microsoft Academic Search

An investigation into the cause of leucoderma among four tappet assembly workers revealed the presence of 4-tertiary butyl catechol (TBC) in the assembly oil. This substance was able to depigment black guinea pig skin in 5% and 10% concentrations in a variety of vehicles. The TBC is an irritant to guinea pig, rabbit, and human skin in concentrations of 0.5%

Gerald A. Gellin; Paul A. Possick; Vernon B. Perone

1970-01-01

53

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

Microsoft Academic Search

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

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

2008-01-01

54

Transfer of bacterial blight and blast resistance from the tetraploid wild rice Oryza minuta to cultivated rice, Oryza sativa  

Microsoft Academic Search

Oryza minuta J. S. Presl ex C. B. Presl is a tetraploid wild rice with resistance to several insects and diseases, including blast (caused by Pyricularia grisea) and bacterial blight (caused by Xanthomonas oryzae pv. oryzae). To transfer resistance from the wild species into the genome of cultivated rice (Oryza sativa L.), backcross progeny (BC1, BC2, and BC3) were produced

A. Amante-Bordeos; L. A. Sitch; R. Nelson; R. D. Dalmacio; N. P. Oliva; H. Aswidinnoor; H. Leung

1992-01-01

55

Catechol and Aldehyde Moieties of 3,4-Dihydroxyphenylacetaldehyde Contribute to Tyrosine Hydroxylase Inhibition and Neurotoxicity  

PubMed Central

Parkinson's disease (PD) is a progressive neurodegenerative disorder which leads to the selective loss of dopaminergic neurons. This causes a decrease in the important neurotransmitter dopamine (DA), which is essential for coordinated movement. Previous studies have implicated the monoamine oxidase metabolite of DA, 3,4-dihydroxphenylacetaldehyde (DOPAL), in the pathogenesis of PD and have shown it to be a reactive intermediate capable of protein modification. DOPAL also has demonstrated the ability to cause mitochondrial dysfunction and lead to significant inhibition of the rate-limiting enzyme in DA synthesis, tyrosine hydroxylase (TH). The current study was undertaken to investigate four analogs of DOPAL, including a novel nitrile analog, to determine how the structure of DOPAL is related to its toxicity and inhibition of TH. Both mitochondrial function and inhibition of TH in cell lysate were investigated. Furthermore, a novel whole cell assay was designed to determine the consequence to enzyme action when DOPAL levels were elevated. The results presented here demonstrate that changes to DOPAL structure lead to a decrease in toxicity and inhibition of enzyme activity as compared to the parent compound. Furthermore, the production of superoxide anion but not hydrogen peroxide increased in the presence of elevated DOPAL. These results reveal the toxicity of DOPAL and demonstrate that both the catechol and aldehyde are required to potently inhibit TH activity.

Vermeer, Lydia M. M.; Florang, Virginia R.; Doorn, Jonathan A.

2012-01-01

56

Genetic Diversity ofXanthomonas oryzaepv. oryzae in Asia  

Microsoft Academic Search

Restriction fragment length polymorphism and virulence analyses were used to evaluate the population structure of Xanthomonas oryzae pv. oryzae, the rice bacterial blight pathogen, from several rice-growing countries in Asia. Two DNA sequences fromX. oryzaepv. oryzae, IS1112, an insertion sequence, andavrXa10, amemberofafamilyofavirulencegenes,wereusedasprobestoanalyzethegenomesof308strainsofX.oryzae pv. oryzae collected from China, India, Indonesia, Korea, Malaysia, Nepal, and the Philippines. On the basis of the

T. B. Adhikari; C. M. Vera Cruz; Q. Zhang; R. J. Nelson; D. Z. Skinner; T. W. Mew; Andj. E. Leach

1995-01-01

57

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

PubMed

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

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

2014-03-01

58

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.

Kreit, Joseph; Sampson, Nicole S.

2009-01-01

59

Functional interplay between two Xanthomonas oryzae pv,. oryzae secretion systems in modulating virulence on rice.  

PubMed

The type II (T2S) and type III (T3S) secretion systems are important for virulence of Xanthomonas oryzae pv. oryzae, causal agent of bacterial leaf blight of rice. The T3S of gram-negative bacterial plant pathogens has been shown to suppress host defense responses, including programmed cell death reactions, whereas the T2S is involved in secreting cell-wall-degrading enzymes. Here, we show that a T3S-deficient (T3S-) mutant of X. oryzae pv. oryzae can induce a basal plant defense response seen as callose deposition, immunize rice against subsequent X. oryzae pv. oryzae infection, and cause cell-death-associated nuclear fragmentation. A T2S- T3S- double mutant exhibited a substantial reduction in the ability to evoke these responses. We purified two major effectors of the X. oryzae pv. oryzae T2S and characterized them to be a cellulase (ClsA) and a putative cellobiosidase (CbsA). The purified ClsA, CbsA, and lipase/esterase (LipA; a previously identified T2S effector) proteins induced rice defense responses that were suppressible by X. oryzae pv. oryzae in a T3S-dependent manner. These defense responses also were inducible by the products of the action of these purified proteins on rice cell walls. We further show that a CbsA- mutant or a ClsA- LipA- double mutant are severely virulence deficient. These results indicate that the X. oryzae pv. oryzae T2S secretes important virulence factors, which induce innate rice defense responses that are suppressed by T3S effectors to enable successful infection. PMID:17249420

Jha, Gopaljee; Rajeshwari, Ramanan; Sonti, Ramesh V

2007-01-01

60

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

Microsoft Academic Search

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

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

2005-01-01

61

Xanthomonas oryzae pv oryzae triggers immediate transcriptomic modulations in rice  

PubMed Central

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

2012-01-01

62

Low catechol-O-methyltransferase activity in a Saami population.  

PubMed

Catechol-O-methyltransferase (COMT) catalyzes the O-methylation of catechol hormones, neurotransmitters and certain drugs. It is subject to genetic polymorphism and ethnic differences. High red blood cell (RBC) COMT activity has been correlated with a poor response to levodopa treatment in Parkinson's disease. RBC COMT was determined in a Norwegian population (n = 213) of whom 115 were Saami (Laaps). The Saami had 16.5% lower RBC COMT activity compared to a non-Saami population sample from the northern part of Norway (n = 50), 13.9 vs. 16.4 units/ml RBC (U) (P = 0.04). This is the first report of any population with lower RBC COMT activity than a Caucasian population. A wide range of RBC COMT activities was found in the entire population examined (1.3-38.3 U). PMID:8070503

Klemetsdal, B; Straume, B; Giverhaug, T; Aarbakke, J

1994-01-01

63

A catechol biosensor based on electrospun carbon nanofibers.  

PubMed

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; Wei, Qufu

2014-01-01

64

Detoxication of Structurally Diverse Polycyclic Aromatic Hydrocarbon (PAH) o-Quinones by Human Recombinant Catechol-O-methyltransferase (COMT) via O-Methylation of PAH Catechols*  

PubMed Central

Polycyclic aromatic hydrocarbons (PAH) are environmental and tobacco carcinogens. Metabolic activation of intermediate PAH trans-dihydrodiols by aldo-keto reductases (AKRs) leads to the formation of electrophilic and redox-active o-quinones. We investigated whether O-methylation by human recombinant soluble catechol-O-methyltransferase (S-COMT) is a feasible detoxication step for a panel of structurally diverse PAH-catechols produced during the redox-cycling process. Classes of PAH non-K-region o-quinones (bay region, methylated bay region, and fjord region o-quinones) produced by AKRs were employed in the studies. PAH o-quinones were reduced to the corresponding catechols by dithiothreitol under anaerobic conditions and then further O-methylated by human S-COMT in the presence of S-[3H]adenosyl-l-methionine as a methyl group donor. The formation of the O-methylated catechols was detected by HPLC-UV coupled with in-line radiometric detection, and unlabeled products were also characterized by LC-MS/MS. Human S-COMT was able to catalyze O-methylation of all of the PAH-catechols and generated two isomeric metabolites in different proportions. LC-MS/MS showed that each isomer was a mono-O-methylated metabolite. 1H NMR was used to assign the predominant positional isomer of benzo[a]pyrene-7,8-catechol as the O-8-monomethylated catechol. The catalytic efficiency (kcat/Km) varied among different classes of PAH-catechols by 500-fold. The ability of S-COMT to produce two isomeric products from PAH-catechols was rationalized using the crystal structure of the enzyme. We provide evidence that O-8-monomethylated benzo[a]pyrene-7,8-catechol is formed in three different human lung cell lines. It is concluded that human S-COMT may play a critical role in the detoxication of PAH o-quinones generated by AKRs.

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

2011-01-01

65

The interplay of catechol ligands with nanoparticulate iron oxides.  

PubMed

The unique properties exhibited by nanoscale materials, coupled with the multitude of chemical surface derivatisation possibilities, enable the rational design of multifunctional nanoscopic devices. Such functional devices offer exciting new opportunities in medical research and much effort is currently invested in the area of "nanomedicine", including: multimodal imaging diagnostic tools, platforms for drug delivery and vectorisation, polyvalent, multicomponent vaccines, and composite devices for "theranostics". Here we will review the surface derivatisation of nanoparticulate oxides of iron and iron@iron-oxide core-shells. They are attractive candidates for MRI-active therapeutic platforms, being potentially less toxic than lanthanide-based materials, and amenable to functionalisation with ligands. However successful grafting of groups onto the surface of iron-based nanoparticles, thus adding functionality whilst preserving their inherent properties, is one of the most difficult challenges for creating truly useful nanodevices from them. Functionalised catechol-derived ligands have enjoyed success as agents for the masking of superparamagnetic iron-oxide particles, often so as to render them biocompatible with medium to long-term colloidal stability in the complex chemical environments of biological milieux. In this perspective, the opportunities and limitations of functionalising the surfaces of iron-oxide nanoparticles, using coatings containing a catechol-derived anchor, are analysed and discussed, including recent advances using dopamine-terminated stabilising ligands. If light-driven ligand to metal charge transfer (LMCT) processes, and pH-dependent ligand desorption, leading to nanoparticle degradation under physiologically relevant conditions can be suppressed, colloidal stability of samples can be maintained and toxicity ascribed to degradation products avoided. Modulation of the redox behaviour of iron catecholate systems through the introduction of an electron-withdrawing substituent to the aromatic ?-system of the catechol is a promising approach towards achieving these goals. PMID:22241454

Yuen, Alexander K L; Hutton, Georgina A; Masters, Anthony F; Maschmeyer, Thomas

2012-03-01

66

Catechol-o-methyltransferase and 3,4-({+/-})-methylenedioxymethamphetamine toxicity.  

PubMed

Metabolism of 3,4-(±)-methylenedioxymethamphetamine (MDMA) is necessary to elicit its neurotoxic effects. Perturbations in phase I and phase II hepatic enzymes can alter the neurotoxic profile of systemically administered MDMA. In particular, catechol-O-methyltransferase (COMT) plays a critical role in determining the fraction of MDMA that is converted to potentially neurotoxic metabolites. Thus, cytochrome P450 mediated demethylenation of MDMA, or its N-demethylated metabolite, 3,4-(±)-methylenedioxyamphetamine, give rise to the catechols, N-methyl-?-methyldopamine and ?-methyldopamine, respectively. Methylation of these catechols by COMT limits their oxidation and conjugation to glutathione, a process that ultimately gives rise to neurotoxic metabolites. We therefore determined the effects of modulating COMT, a critical enzyme involved in determining the fraction of MDMA that is converted to potentially neurotoxic metabolites, on MDMA-induced toxicity. Pharmacological inhibition of COMT in the rat potentiated MDMA-induced serotonin deficits and exacerbated the acute MDMA-induced hyperthermic response. Using a genetic mouse model of COMT deficiency, in which mice lack a functional COMT gene, such mice displayed greater reductions in dopamine concentrations relative to their wild-type (WT) counterparts. Neither WT nor COMT deficient mice were susceptible to MDMA-induced decreases in serotonin concentrations. Interestingly, mice devoid of COMT were far more susceptible to the acute hyperthermic effects of MDMA, exhibiting greater increases in body temperature that ultimately resulted in death. Our findings support the view that COMT plays a pivotal role in determining the toxic response to MDMA. PMID:24591155

Herndon, Joseph M; Cholanians, Aram B; Lizarraga, Lucina E; Lau, Serrine S; Monks, Terrence J

2014-05-01

67

Immobilization of Amphiphilic Polycations by Catechol Functionality for Antimicrobial Coatings  

PubMed Central

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

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

2011-01-01

68

Purification and characterization of polyphenol oxidase from rape flower.  

PubMed

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

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

2012-01-25

69

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

SciTech Connect

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

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

2012-11-15

70

Structure and vibrations of catechol in the S 1 state and ionic ground state  

Microsoft Academic Search

To determine structure and vibrations of catechol and d2-catechol (C6H4(OD)2) in the ionic ground state, MATI spectra as well as ab initio and DFT calculations are presented. The comparison of the experimentally observed vibrational frequencies with the calculated values leads to a complete assignment of all vibrations. CASSCF and DFT calculations predict a planar geometry of catechol in the S0

M. Gerhards; S. Schumm; C. Unterberg; K. Kleinermanns

1998-01-01

71

Electrochemical Oxidation of Catechols in the Presence of Pyrimidine2-thiol: Application to Electrosynthesis  

Microsoft Academic Search

The electrooxidation of catechols (1a–d) in the presence of pyrimidine-2-thiol (3) as a nucleophile in aqueous solution is described. The mechanistic investigations using cyclic voltammetry and controlled potential coulometry indicate that the quinone derived from catechols participates in a Michael addition reaction with pyrimidine-2-thiol to form corresponding catechol derivatives of 6a–d (ECEC). The efficient electrosynthesis of 6a–d has been performed

Lida Fotouhi; Ladan Behrozi; Majid M. Heravi; Davood Nematollahi

2009-01-01

72

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

PubMed Central

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

2013-01-01

73

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

PubMed

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

Aghapour, Ali Ahmad; Moussavi, Gholamreza; Yaghmaeian, Kamyar

2013-01-01

74

CGP 28014, a new inhibitor of cerebral catechol-O-methylation with a non-catechol structure  

Microsoft Academic Search

CGP 28014 (N-(2-pyridone-6-yl)-N',N'-di-n-propylformamidine) or its methanesulfonate salt CGP 28014 A was suspected to be a catechol-O-methyl-transferase (COMT) inhibitor because it was found to reduce the levels of homovanillic acid (HVA) and to increase those of 3,4-dihydroxyphenylacetic acid (DOPAC) in the rat striatum, after oral or intraperitoneal administration. These effects were maintained after repeated administration. The compound was only weakly active

P. C. Waldmeier; P. A. Baumann; J. J. Feldtrauer; K. Hauser; H. Bittiger; S. Bischoff; G. Sprecher

1990-01-01

75

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

76

Stationary-phase variation due to transposition of novel insertion elements in Xanthomonas oryzae pv. oryzae.  

PubMed

Xanthomonas oryzae pv. oryzae causes bacterial leaf blight, a serious disease of rice. Spontaneous mutants which are deficient for virulence and extracellular polysaccharide (Eps) production accumulate in large numbers in stationary-phase cultures of this bacterium, a phenomenon which we have called stationary-phase variation. A clone (pSD1) carrying the Eps biosynthetic gene (gum) cluster of X. oryzae pv. oryzae restored Eps production and virulence to several spv (for stationary-phase variation) mutants. Data from localized recombination analysis, Southern hybridization, PCR amplification, and sequence analysis showed that the mutations are due to insertion of either one of two novel endogenous insertion sequence (IS) elements, namely, ISXo1 and ISXo2, into gumM, the last gene of the gum gene cluster. The results of Southern analysis indicate the presence of multiple copies of both IS elements in the genome of X. oryzae pv. oryzae. These results demonstrate the role of IS elements in stationary-phase variation in X. oryzae pv. oryzae. PMID:10940020

Rajeshwari, R; Sonti, R V

2000-09-01

77

Detection of Xanthomonas oryzae pv. oryzae in seeds using a specific TaqMan probe.  

PubMed

Xanthomonas oryzae pv. oryzae is the pathogen that causes bacterial leaf blight in rice. Bacterial leaf blight is the main cause for severe rice underproduction in many countries. However, with conventional methods it is difficult to quickly and reliably distinguish this pathogen from other closely related pathogenic bacteria, especially X. oryzae pv. oryzicola, the causal organism of bacterial leaf streak in rice. We have developed a novel and highly sensitive real-time method for the identification of this specific bacteria based on a TaqMan probe. This probe is designed to recognize the sequence of a putative siderophore receptor gene cds specific to X. oryzae pv. oryzae, and can be identified from either a bacterial culture or naturally infected rice seeds and leaves in only 2 h. The sensitivity of the method is 100 times higher than that of the current polymerase chain reaction (PCR) gel electrophoresis method for diagnosis. PMID:17435277

Zhao, Wen-Jun; Zhu, Shui-Fang; Liao, Xiao-Lan; Chen, Hong-Yun; Tan, Tian-Wei

2007-02-01

78

Mutational analysis of the gum gene cluster required for xanthan biosynthesis in Xanthomonas oryzae pv oryzae.  

PubMed

Genome sequence analysis of Xanthomonas oryzae pv. oryzae has revealed a cluster of 12 ORFs that are closely related to the gum gene cluster of Xanthomonas campestris pv. campestris. The gum gene cluster of X. oryzae encodes proteins involved in xanthan production; however, there is little experimental evidence supporting this. In this study, biochemical analyses of xanthan produced by a defined set of X. oryzae gum mutant strains allowed us to preliminarily assign functions to most of the gum gene products: biosynthesis of the pentasaccharide repeating unit for GumD, GumM, GumH, GumK, and GumI, xanthan polymerization and transport for GumB, GumC, GumE, and GumJ, and modification of the pentasaccharide repeating unit for GumF, GumG, and GumL. In addition, we found that the exopolysaccharides are essential but not specific for the virulence of X. oryzae. PMID:18854951

Kim, Sang-Yoon; Kim, Jeong-Gu; Lee, Byoung-Moo; Cho, Jae-Yong

2009-02-01

79

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

80

Some kinetic properties of polyphenol oxidase obtained from dill (Anethum graveolens).  

PubMed

Polyphenol oxidase (PPO) was partially purified from dill by (NH4)(2)SO4 precipitation followed by dialysis and gel filtration chromatography. Polyphenol oxidase activity was measured spectrophotometrically at 420 nm using catechol, dopamine and chlorogenic acid as substrates. Optimum pH, temperature, and ionic strength were determined with three substrates. The best substrate of dill PPO was found to be chlorogenic acid. Some kinetic properties of the enzyme such as V(max,) K(M) and V(max)/K(M) were determined for all three substrates. The effects of various inhibitors on the reaction catalysed by the enzyme were tested and I(50) values calculated. The most effective inhibitor was L-cysteine. Activation energies, E(a), were determined from the Arrhenius equation. In addition, activation enthalpy, DeltaH(a), and Q(10) values of the enzyme were also calculated. PMID:18569343

Sakiro?lu, Halis; Oztürk, Ahmet Emin; Pepe, Anil Ece; Erat, Mustafa

2008-06-01

81

Crystal Structures of Human 108V and 108M Catechol O-Methyltransferase  

Microsoft Academic Search

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.

K. Rutherford; I. Le Trong; R. E. Stenkamp; W. W. Parson

2008-01-01

82

CCMR: The Synthesis of Covalent Organic Frameworks From Acetonide-Protected Polyfunctional Catechols.  

NSDL National Science Digital Library

The formation and exchange of boronate ester moieties associated with the synthesis of boronate ester-linked covalent organic frameworks (COFs) has been investigated from acetonide-protected catechol and phenylboronic acid starting materials. Acetonideprotected catechol reacts with phenylboronic acid in the presence of the Lewis acid boron triflouride etherate (BF3OEt2) to afford the corresponding catechol boronic ester. Catechol phenylboronate undergoes exchange in the presence of BF3OEt2 with excess boronic acid or catechol, both important processes for the formation of well-ordered COF materials. These mechanistic studies were used to optimize the reaction of acetonideprotected 2,3,6,7,10,11-hexahydroxytriphenylene with bis(boronic) acids to provide crystalline samples of two previously reported COFs, indicating the utility of this new synthetic method for the preparation of these materials.

White, Sarah L.

2009-08-15

83

Improved performance of protected catecholic polysiloxanes for bio-inspired wet adhesion to surface oxides  

PubMed Central

A facile synthetic strategy for introducing catecholic moieties into polymeric materials based on a readily available precursor – eugenol – and efficient chemistries – tris(pentafluorophenyl)borane catalyzed silation and thiol-ene coupling is reported. Silyl-protection is shown to be critical for the oxidative stability of catecholic moieties during synthesis and processing which allows functionalized polysiloxane derivatives to be fabricated into 3-D microstructures as well as 2-D patterned surfaces. Deprotection gives stable catechol surfaces with adhesion to a variety of oxide surfaces being precisely tuned by the level of catechol incorporation. The advantage of silyl-protection for catechol functionalized polysiloxanes is demonstrated and represents a promising and versatile new platform for underwater surface treatments.

Heo, Jinhwa; Kang, Taegon; Jang, Se Gyu; Hwang, Dong Soo; Spruell, Jason M.; Killops, Kato L.; Waite, J. Herbert; Hawker, Craig J.

2012-01-01

84

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

85

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

PubMed

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

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

2010-07-01

86

Type III Cu mutants of Myrothecium verrucaria bilirubin oxidase.  

PubMed

Type III Cu ligand, His456 and His458, of Myrothecium verrucaria (MT-1) bilirubin oxidases (BO) [EC 1.3.3.5] were doubly mutated as to Lys, Asp, and Val. In spite of perturbation of the type III Cu centers, these mutants were pale blue or colourless when isolated. However, they became intense blue on reaction with reducing agents such as dithionite, ascorbate, hexacyanoferrate(II), and octacyanotangstate(IV) under air, or with an oxidizing agent such as hexacyanoferrate(III), indicating that they are in mixed forms when expressed in Aspergillus oryzae. His456.458Lys and His456.458Asp mutated as to potential coordinating groups showed weak BO and ferroxidase activities, while His 456.458Val mutated as to non-coordinating groups showed no enzyme activity at all. PMID:12869533

Shimizu, Atsushi; Samejima, Tatsuya; Hirota, Shun; Yamaguchi, Shotaro; Sakurai, Nobuhiko; Sakurai, Takeshi

2003-06-01

87

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

PubMed

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

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

2011-07-22

88

Characterization of two brassinosteroid C-6 oxidase genes in pea.  

PubMed

C-6 oxidation genes play a key role in the regulation of biologically active brassinosteroid (BR) levels in the plant. They control BR activation, which involves the C-6 oxidation of 6-deoxocastasterone (6-DeoxoCS) to castasterone (CS) and in some cases the further conversion of CS to brassinolide (BL). C-6 oxidation is controlled by the CYP85A family of cytochrome P450s, and to date, two CYP85As have been isolated in tomato (Solanum lycopersicum), two in Arabidopsis (Arabidopsis thaliana), one in rice (Oryza sativa), and one in grape (Vitis vinifera). We have now isolated two CYP85As (CYP85A1 and CYP85A6) from pea (Pisum sativum). However, unlike Arabidopsis and tomato, which both contain one BR C-6 oxidase that converts 6-DeoxoCS to CS and one BR C-6 Baeyer-Villiger oxidase that converts 6-DeoxoCS right through to BL, the two BR C-6 oxidases in pea both act principally to convert 6-DeoxoCS to CS. The isolation of these two BR C-6 oxidation genes in pea highlights the species-specific differences associated with C-6 oxidation. In addition, we have isolated a novel BR-deficient mutant, lke, which blocks the function of one of these two BR C-6 oxidases (CYP85A6). The lke mutant exhibits a phenotype intermediate between wild-type plants and previously characterized pea BR mutants (lk, lka, and lkb) and contains reduced levels of CS and increased levels of 6-DeoxoCS. To date, lke is the only mutant identified in pea that blocks the latter steps of BR biosynthesis and it will therefore provide an excellent tool to further examine the regulation of BR biosynthesis and the relative biological activities of CS and BL in pea. PMID:17322341

Jager, Corinne E; Symons, Gregory M; Nomura, Takahito; Yamada, Yumiko; Smith, Jennifer J; Yamaguchi, Shinjiro; Kamiya, Yuji; Weller, James L; Yokota, Takao; Reid, James B

2007-04-01

89

Functional analysis of the aroC gene encoding chorismate synthase from Xanthomonas oryzae pathovar oryzae.  

PubMed

Xanthomonas oryzae pv. oryzae causes bacterial blight in rice, and this bacterial blight has been widely found in the major rice-growing areas. We constructed a transposon mutagenesis library of X. oryzae pv. oryzae and identified a mutant strain (KXOM9) that is deficient for pigment production and virulence. Furthermore, the KXOM9 mutant was unable to grow in minimal medium lacking aromatic amino acids. Thermal asymmetric interlaced-PCR and sequence analysis of KXOM9 revealed that the transposon was inserted into the aroC gene, which encodes a chorismate synthase in various bacterial pathogens. In planta growth assays revealed that bacterial growth of the KXOM9 mutant in rice leaves was severely reduced. Genetic complementation of this mutant with a 7.9-kb fragment containing aroC restored virulence, pigmentation, and prototrophy. These results suggest that the aroC gene plays a crucial role in the growth, attenuation of virulence, and pigment production of X. oryzae pv. oryzae. PMID:22169355

Song, Eun-Sung; Park, Young-Jin; Noh, Tae-Hwan; Kim, Yeong-Tae; Kim, Jeong-Gu; Cho, Heejung; Lee, Byoung-Moo

2012-06-20

90

Multicopper oxidases and oxygenases  

Microsoft Academic Search

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

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

1996-01-01

91

Xanthomonas oryzae pathovars: model pathogens of a model crop.  

PubMed

SUMMARY Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola cause bacterial blight and bacterial leaf streak of rice (Oryza sativa), which constrain production of this staple crop in much of Asia and parts of Africa. Tremendous progress has been made in characterizing the diseases and breeding for resistance. X. oryzae pv. oryzae causes bacterial blight by invading the vascular tissue, while X. oryzae pv. oryzicola causes bacterial leaf streak by colonizing the parenchyma. In rice there are 29 major genes for resistance to bacterial blight, but so far only a few quantitative resistance loci for bacterial leaf streak. Over 30 races of X. oryzae pv. oryzae have been reported. Both pathogens exhibit genetic variation among isolates. Mechanisms of pathogenesis and resistance have begun to be elucidated. Members of the AvrBs3/PthA family of transcription activator-like effectors play a major role in the virulence of X. oryzae pv. oryzae and possibly X. oryzae pv. oryzicola. Cloning of six rice resistance genes for bacterial blight and one from maize effective against bacterial leaf streak has uncovered a diversity of structure and function, some shared by genes involved in defence in animals. This article reviews research that spans a century. It also presents a perspective on challenges for sustainable control, and opportunities that interactions of X. oryzae pathovars with rice present as models for understanding fundamental aspects of bacterial pathogenesis of plants and plant disease resistance, as well as other aspects of plant and microbial biology, with implications also for animal innate immunity. PMID:20507449

Nińo-Liu, David O; Ronald, Pamela C; Bogdanove, Adam J

2006-09-01

92

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

93

Phenol oxidase activity in secondary transformed peat-moorsh soils  

NASA Astrophysics Data System (ADS)

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

Sty?a, K.; Szajdak, L.

2009-04-01

94

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.

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

95

Utilization of acorn fringe for ellagic acid production by Aspergillus oryzae and Endomyces fibuliger.  

PubMed

Conversion of acorn fringe extract into ellagic acid production by Aspergillus oryzae and Endomyces fibuliger were investigated. The results showed that ellagic acid production was maximized when co-fermentation of the two fungi was performed at 30 degrees C and pH 5.0 with 5.7 g/l of initial substrate concentration, which were close to the optimal values for both fungi to yield an appropriate consortium of hydrolytic enzymes. Meanwhile, it was found that the co-fermentation could compensate the deficiencies in the level of polyphenol oxidase activity from pure A. oryzae and the levels of ellagitannin acyl hydrolase and beta-glucosidase activities from pure E. fibuliger, resulting in. 0.91 g/l of biomass concentration containing 1.84 g/l of ellagic acid. The research not only demonstrates that the co-fermentation is an effective approach to utilize forest byproduct for ellagic acid production, but also provides more evidences for understanding evolution of ellagic acid production with enzymes actions, which is important for process control of ellagic acid production in industrial application. PMID:17826988

Huang, Wen; Li, Zhenshan; Niu, Hai; Li, Lulu; Lin, Wensheng; Yang, Jinshui

2008-06-01

96

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

PubMed

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

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

2013-06-01

97

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

PubMed

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

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

2012-10-01

98

Identification of novel type III secretion effectors in Xanthomonas oryzae pv. oryzae.  

PubMed

Many gram-negative bacteria secrete so-called effector proteins via a type III secretion (T3S) system. Through genome screening for genes encoding potential T3S effectors, 60 candidates were selected from rice pathogen Xanthomonas oryzae pv. oryzae MAFF311018 using these criteria: i) homologs of known T3S effectors in plant-pathogenic bacteria, ii) genes with expression regulated by hrp regulatory protein HrpX, or iii) proteins with N-terminal amino acid patterns associated with T3S substrates of Pseudomonas syringae. Of effector candidates tested with the Bordetella pertussis calmodulin-dependent adenylate cyclase reporter for translocation into plant cells, 16 proteins were translocated in a T3S system-dependent manner. Of these 16 proteins, nine were homologs of known effectors in other plant-pathogenic bacteria and seven were not. Most of the effectors were widely conserved in Xanthomonas spp.; however, some were specific to X. oryzae. Interestingly, all these effectors were expressed in an HrpX-dependent manner, suggesting coregulation of effectors and the T3S system. In X. campestris pv. vesicatoria, HpaB and HpaC (HpaP in X. oryzae pv. oryzae) have a central role in recruiting T3S substrates to the secretion apparatus. Secretion of all but one effector was reduced in both HpaB() and HpaP() mutant strains, indicating that HpaB and HpaP are widely involved in efficient secretion of the effectors. PMID:19061406

Furutani, Ayako; Takaoka, Minako; Sanada, Harumi; Noguchi, Yukari; Oku, Takashi; Tsuno, Kazunori; Ochiai, Hirokazu; Tsuge, Seiji

2009-01-01

99

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

Microsoft Academic Search

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

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

2001-01-01

100

Structure and reaction mechanism of catechol 2,3-dioxygenase (metapyrocatechase)  

Microsoft Academic Search

Catechol 2,3-dioxygenases catalyzes the extradiol ring-cleavage of catechol derivatives. The enzyme from Pseudomonas putida mt-2 (metapyrocatechase, MPC) is a homotetramer and prefers small monocyclic substrates. We have structurally characterized MPC at a 2.8-Ĺ resolution in the presence of 10% acetone. The subunit comprises the N- and C-terminal domains of a similar structure. The active site is located in a funnel-shaped

Tetsuo Ishida; Akiko Kita; Kunio Miki; Mitsuhiro Nozaki; Kihachiro Horiike

2002-01-01

101

Catechol monophosphate as a new substrate for screen-printed amperometric biosensors with immobilized phosphatases  

Microsoft Academic Search

Catechol monophoshate (CMP) is proposed as a new substrate for determination of activity of alkaline phosphatase and protein phosphatase for amperometric biosensors. The product of its enzymatic hydrolysis, catechol, is oxidized at a graphite screen-printed electrode in the potential range from +0.2 to 0.5V versus Ag\\/AgCl depending on pretreatment and modification of the surface of the working electrode. A linear

Dorota Szyd?owska; Mňnica Campŕs; Jean-Louis Marty; Marek Trojanowicz

2006-01-01

102

Stark spectroscopy of charge-transfer transitions in catechol-sensitized TiO 2 nanoparticles  

Microsoft Academic Search

Electronic excited states of catechol bound to titanium dioxide nanoparticles were investigated using electroabsorption (Stark effect) spectroscopy. The electronic transition at about 400nm, characteristic for catechol bound to TiO2 is associated with a change in permanent dipole moment by f·|??|=15.7D (where f is the local field correction factor), and a small negative change in the polarizability. Electron transfer distance points

Agnieszka Nawrocka; Agata Zdyb; Stanislaw Krawczyk

2009-01-01

103

Crystal structures of rat catechol- O-methyltransferase complexed with coumarine-based inhibitor  

Microsoft Academic Search

In human, catechol-O-methyltransferase (COMT: E.C. 2.1.1.6) is responsible for metabolism of catechol neurotransmitter and xenobiotics. The main clinical interest in COMT results from the possibility of using COMT inhibitors as adjuncts in the therapy of Parkinson’s disease (PD) with l-DOPA. COMT is therefore a target for inhibitor development aiming at PD treatment and has been submitted to extensive structure-based drug

Eiichi Tsuji; Kosuke Okazaki; Kei Takeda

2009-01-01

104

Characterization of catechol derivative removal by lignin peroxidase in aqueous mixture.  

PubMed

The use of lignin peroxidase (LIP) as an alternative method for the removal of four catechols (1,2-dihydroxybenzene): catechol (CAT), 4-chlorocatechol (4-CC), 4,5-dichlorocatechol (4,5-DCC) and 4-methylcatechol (4-MC) typical pollutants in wastewater derived from oil and paper industries, was evaluated. The removal of 2mM catecholic substrates by 1 microM LIP after 1h was in the following order: 4,5-DCC (95%)>4-CC(90%)>CAT(55%)>4-MC(43%). Except for 4-MC, all reactions were accompanied by the formation of insoluble products, leading to LIP precipitation. LIP was exposed to soluble or insoluble product-dependent inactivation, depending on the substrates tested, immediately at the start of the reactions. Despite immediate enzyme inactivation, removal of catecholic substrates continued, resulting in oligomeric product formation. Major oxidation products analyzed were compatible with dimeric, trimeric and tetrameric structures. Ether linkages and a benzoquinone structure were detected in two purified oligochlorocatechols. Catechol derivatives removal initiated by LIP, seems to be different for each catecholic substrate in terms of substrate consumption and transformation, and of enzyme activity. PMID:19097884

Cohen, Shaul; Belinky, Paula A; Hadar, Yitzhak; Dosoretz, Carlos G

2009-04-01

105

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

106

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

Microsoft Academic Search

A new chromatographic catechol O-methyltransferase (COMT) assay based on S-adenosyl-l-[methyl-14C]methionine and on-line radioactivity detection was developed. With minor modifications in the mobile phase composition the methylation velocities for 30 structurally diverse compounds including simple catechols, neurotransmitters, catecholestrogens and catecholic drugs could be measured using human and rat recombinant soluble COMT. The enzymes showed very similar substrate selectivities. The radiochemical method

Pia Lautala; Ismo Ulmanen; Jyrki Taskinen

1999-01-01

107

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

108

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

PubMed Central

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

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

2014-01-01

109

NADPH Oxidase and Neurodegeneration  

PubMed Central

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

Hernandes, Marina S; Britto, Luiz R G

2012-01-01

110

Enantioselectivity in the methylation of the catecholic phase I metabolites of methylenedioxy designer drugs and their capability to inhibit catechol-O-methyltransferase-catalyzed dopamine 3-methylation.  

PubMed

The designer drugs R,S-3,4-methylenedioxy-methamphetamine (MDMA, Ecstasy), R,S-3,4-methylenedioxy-ethylamphetamine (MDEA, Eve), and R,S-N-methyl-benzodioxolyl-butanamine (MBDB, Eden) are chiral compounds, and their in vitro and in vivo metabolism is enantioselective with a preference for the S-enantiomer caused in part by P450-mediated demethylenation. As the elimination of the catecholamine metabolites could also be enantioselective, the aim of the present study was to investigate the O-methylation to the corresponding methoxy derivatives catalyzed by the soluble or membrane-bound form of the catechol-O-methyltransferase (COMT). As all three compounds showed substrate inhibition effects during the incubation, their inhibition potential was quantified using the methylation of dopamine as a marker reaction. For investigation of the catechol-O-methylation catalyzed by the soluble form of the COMT (sCOMT), incubations with human liver cytosol (HLC) were performed. Human liver microsomes (HLM) were used for investigation of the membrane-bound form. For inhibition studies, 3-hydroxytyramine (dopamine) was incubated in HLC. The respective catechols were added at various concentrations to check whether they influence the methylation of 3-hydroxytyramine. Our data showed that the S-enantiomers of all studied catecholamines were preferably O-methylated by both types of COMT. Comparing the resulting kinetics of the HLC and HLM assays, the affinity for all substrates was 10-fold higher for the membrane-bound COMT, whereas the turnover rate was 10-fold higher for the soluble COMT. Uncompetitive inhibition of dopamine methylation could be observed for all tested catechols. In conclusion, elimination of the catecholamine metabolites of MDMA, MDEA, and MBDB was shown to be enantioselective and might therefore contribute to the different pharmacokinetic properties observed for both enantiomers. Furthermore, the catecholic metabolites were identified to be uncompetitive inhibitors of the sCOMT localized in HLC. PMID:19462939

Meyer, Markus R; Maurer, Hans H

2009-06-01

111

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

PubMed

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

Pandey, Alok; Sonti, Ramesh V

2010-06-01

112

Relation Between the Adsorbed Quantity and the Immersion Enthalpy in Catechol Aqueous Solutions on Activated Carbons  

PubMed Central

An activated carbon, CarbochemTM—PS230, was modified by chemical and thermal treatment in flow of H2, in order to evaluate the influence of the activated carbon chemical characteristics in the adsorption of the catechol. The catechol adsorption in aqueous solution was studied along with the effect of the pH solution in the adsorption process of modified activated carbons and the variation of immersion enthalpy of activated carbons in the aqueous solutions of catechol. The interaction solid-solution is characterized by adsorption isotherms analysis, at 298 K and pH 7, 9 and 11 in order to evaluate the adsorption value above and below that of the catechol pKa. The adsorption capacity of carbons increases when the solution pH decreases. The retained amount increases slightly in the reduced carbon to maximum adsorption pH and diminishes in the oxidized carbon. Similar conclusions are obtained from the immersion enthalpies, whose values increase with the solute quantity retained. In granular activated carbon (CAG), the immersion enthalpies obtained are between 21.5 and 45.7 J·g?1 for catechol aqueous solutions in a range of 20 at 1500 mg·L?1.

Moreno-Pirajan, Juan Carlos; Blanco, Diego; Giraldo, Liliana

2012-01-01

113

Protection of rat hepatocytes from tert-butyl hydroperoxide-induced injury by catechol.  

PubMed

Metabolism of tert-butyl hydroperoxide (TBHP, 2.0 mM) by glutathione peroxidase within isolated rat hepatocytes caused a rapid oxidation of intracellular reduced glutathione and ultimately NADPH through glutathione reductase. TBHP also caused the formation of surface blebs in the hepatocyte plasma membrane followed by the leakage of cytosolic enzymes, such as lactate dehydrogenase, into the incubation medium. Catechol (0.1 mM) protected hepatocytes from the cytotoxic effects of TBHP but did not prevent the rapid oxidation of glutathione indicating normal metabolism of TBHP through glutathione reductase. In contrast, addition of catechol to the hepatocyte incubations prevented TBHP-induced depletion of intracellular NADPH and increased the total NADP+ + NADPH concentration without altering significantly the intracellular NADP+ content or the NADPH/NADP + NADPH ratio. Catechol did not alter TBHP stimulation of the pentose phosphate pathway. Hepatocytes incubated with sublethal concentrations of TBHP (1.0 mM) did not leak lactate dehydrogenase into the medium but did lose intracellular potassium. In these experiments, TBHP caused a sustained increase in phosphorylase alpha activity suggesting that TBHP metabolism may be associated with a sustained increase in cytosolic free Ca2+. In the presence of catechol, phosphorylase alpha activity was increased by 5 min but returned toward control by 20 min. These data suggest that catechol may be protecting hepatocytes from TBHP-induced injury by preventing a sustained rise in cytosolic free Ca2+ concentration. PMID:3726880

Rush, G F; Yodis, L A; Alberts, D

1986-07-01

114

Myocardial xanthine oxidase/dehydrogenase.  

PubMed

High-energy phosphates in heart muscle deprived of oxygen are rapidly broken down to purine nucleosides and oxypurines. We studied the role of xanthine oxidase/dehydrogenase (EC 1.2.3.2/EC 1.2.1.37) in this process with novel high-pressure liquid chromatographic techniques. Under various conditions, including ischemia and anoxia, the isolated perfused rat heart released adenosine, inosine and hypoxanthine, and also substantial amounts of xanthine and urate. Allopurinol, an inhibitor of xanthine oxidase, greatly enhanced the release of hypoxanthine. From the purine release we calculated that the rat heart contained about 18 mU xanthine oxidase per g wet weight. Subsequently, we measured a xanthine oxidase activity of 9 mU/g wet wt. in rat-heart homogenate. When endogenous low molecular weight inhibitors were removed by gel-filtration, the activity increased to 31 mU/g wet wt. Rat myocardial xanthine oxidase seems to be present mainly in the dehydrogenase form, which upon storage at -20 degrees C is converted to the oxidase form. PMID:6575831

Schoutsen, B; De Jong, J W; Harmsen, E; De Tombe, P P; Achterberg, P W

1983-07-14

115

Ortho-substituted catechol derivatives: the effect of intramolecular hydrogen-bonding pathways on chloride anion recognition.  

PubMed

This paper reports a series of chloride anion receptors containing two catechol head groups connected through their ortho-positions via a spacer chain. The linking group chosen to attach the spacer chain to the catechol units has a major impact on the anion-binding potential of the receptor. Linking groups that are capable of forming stable six-membered intramolecular hydrogen-bonded rings with the catechol O-H groups significantly inhibit the ability of the catechol units to hydrogen bond to chloride anions. However, where the linking groups are only capable of forming five- or seven-membered intramolecular hydrogen-bonded rings, then anion binding via hydrogen bonding through the catechol O-H groups becomes a possibility. This process is solvent dependent; the presence of competitive solvent (e.g., DMSO-d6) disrupts the intramolecular hydrogen-bonding pattern and enhances anion binding relative to simple unfunctionalized catechol. The most effective receptor is that in which the hydrogen-bonding linker (-CH2CONH-) is most distant from the catechol units and can only form a seven-membered intramolecular hydrogen-bonded ring. In this case, the receptor, which contains two catechol units, is a more effective chloride anion binder than simple unfunctionalized catechol, demonstrating that the two head groups, in combination with the N-H groups in the linker, act cooperatively and enhance the degree of anion binding. In summary, this paper provides insight into the hydrogen-bonding patterns in ortho-functionalized catechols and the impact these have on the potential of the catechol O-H groups to hydrogen bond to a chloride anion. PMID:17362039

Winstanley, Keith J; Smith, David K

2007-04-13

116

Polyphenol oxidases from latex of Hevea brasiliensis: purification and characterization.  

PubMed

Polyphenol oxidase (PPO) was isolated from the B-serum obtained after repetitive freeze-thawing of the bottom fraction isolated from ultracentrifuged fresh latex. The B-serum was subjected to acetone precipitation and CM-Sepharose chromatography, affording two PPOs, PPO-I and PPO-II, which, upon SDS-PAGE, were 32 and 34 kDa, respectively. Both PPOs possessed the same pI (9.2), optimum pH (7) and optimum temperature (35-45 degrees C). They are stable up to 60 degrees C and active at broad pH ranges from 4-9. The K(m) values of PPO-I for dopamine, L-dopa and catechol as substrates are 2.08, 8.33 and 9.09 mM, while those for PPO-II are 2.12, 4.76 and 7.14 mM, respectively. Among various PPO inhibitors tested, 4-hexylresorcinol was the most potent. Anionic detergents were among the most effective activators of the enzymes, while cationic and nonionic detergents showed little and no effect on the PPO activities, respectively. PMID:12169303

Wititsuwannakul, Dhirayos; Chareonthiphakorn, Nopphakaew; Pace, Mario; Wititsuwannakul, Rapepun

2002-09-01

117

Defense-related polyphenol oxidase from Hevea brasiliensis cell suspension: purification and characterization.  

PubMed

Polyphenol oxidase (PPO) was examined from the extract of leaf, seed, and cell suspension of Hevea brasiliensis, a rubber plant. The defense-related isozyme from Hevea cell suspension induced by culture filtrate of Phytophthora palmivora or by agitation stress was isolated through anion exchange and affinity chromatography, respectively. A 104-purification fold, migrated as a single band of 70 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis of PPO, was obtained after further purified by the preparative gel electrophoresis. Based on reaction with catechol and dopamine but not with p-cresol and guaiacol, it is a diphenol-type PPO. The values of V(max)/K(m) ratio indicated that catechol was the most specific substrate. The optimal activity of the purified PPO was observed at pH 6.0. The PPO activity was retained at pH 4.0-10.0 and temperature 10-60 °C. The inhibitors which completely inhibited the activity were ascorbic acid, dithiothreitol, and ?-mercaptoethanol while sodium azide was a poor inhibitor. The PPO obtained from Hevea cell suspension possesses high specific activity and is stable at wide range of pH and temperature. It is therefore suitable for extreme condition uses and may lead to an alternative source of PPO in various industrial applications. PMID:22532343

Muhamad, Nisaporn; Chirapongsatonkul, Nion; Churngchow, Nunta

2012-05-01

118

Partial purification of polyphenol oxidase from Chinese cabbage Brassica rapa L.  

PubMed

Polyphenol oxidase (PPO) was purified and characterized from Chinese cabbage by ammonium sulfate precipitation and DEAE-Toyopearl 650M column chromatography. Substrate staining of the crude protein extract showed the presence of three isozymic forms of this enzyme. The molecular weight of the purified enzyme was estimated to be approximately 65 kDa by gel filtration on Toyopearl HW-55F. On SDS-PAGE analysis, this enzyme was composed of a subunit molecular weight of 65 kDa. The optimum pH was 5.0, and this enzyme was stable at pH 6.0 but was unstable below pH 4.0 or above pH 7.0. The optimum temperature was 40 degrees C. Heat inactivation studies showed temperatures >40 degrees C resulted in loss of enzyme activity. PPO showed activity to catechol, pyrogallol, and dopamine (K(m) and V(max) values were 682.5 mM and 67.6 OD/min for catechol, 15.4 mM and 14.1 OD/min for pyrogallol, and 62.0 mM and 14.9 OD/min for dopamine, respectively). The most effective inhibitor was 2-mercaptoethanol, followed in decreasing order by ascorbic acid, glutathione, and L-cysteine. The enzyme activity of the preparation was maintained for 2 days at 4 degrees C but showed a sudden decreased after 3 days. PMID:11513690

Nagai, T; Suzuki, N

2001-08-01

119

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

120

Structure and kinetics of formation of catechol complexes of ferric soybean lipoxygenase-1  

SciTech Connect

Ferric soybean lipoxygenase forms stable complexes with 4-substituted catechols. The structure of the complex between the enzyme and 3,4-dihydroxybenzonitrile has been studied by resonance Raman, electron paramagnetic resonance, visible, and X-ray spectroscopies. It is a bidentate iron-catecholate complex with at least one water ligand. The kinetics of formation of complexes between lipoxygenase and 3,4-dihydroxybenzonitrile and 3,4-dihydroxyacetophenone have been studied by stopped-flow spectroscopy. The data are consistent with two kinetically distinct, reversible steps. The pH dependence of the first step suggests that the substrate for the reaction is the catechol monoanion. When these results are combined, plausible mechanisms for the complexation reaction are suggested. 51 refs., 12 figs., 2 tabs.

Nelson, M.J.; Brennan, B.A.; Chase, D.B. [E.I. du Pont de Nemours & Co., Wilmington, DE (United States)]|[Haverford College, PA (United States)] [and others

1995-11-21

121

Modification of the effects of guanethidine on cardiac catechol amines by various agents  

PubMed Central

A study has been made of the effect of injections of guanethidine in rats, in depleting catechol amines from the whole cardiac ventricles and from various subcellular fractions. Unlike reserpine, guanethidine first affected the concentration of the amines in the soluble fraction of the cell. Neither [2-(2,6-dimethylphenoxy)-propyl]trimethylammonium chloride monohydrate (?-methyl xylocholine) nor hemicholinium affected the endogenous catechol amines or the uptake of injected noradrenaline, but each significantly reduced the action of guanethidine in depleting catechol amines. Administration of choline chloride after hemicholinium reversed its influence on guanethidine depletion. In cats, cocaine potentiated the pressor response to noradrenaline, but antagonized the response to tyramine and guanethidine, while bretylium and N-o-chlorobenzyl-N'N”-dimethylguanidine sulphate (BW392C60) potentiated the responses to noradrenaline, tyramine and guanethidine.

Bhagat, B.

1964-01-01

122

Synthesis and anticholinesterase activity of huperzine A analogues containing phenol and catechol replacements for the pyridone ring  

Microsoft Academic Search

Based upon modeling results obtained using the crystal structure of huperzine A in complex with acetylcholinesterase (AChE), two novel analogues of this potent AChE inhibitor were designed with phenol or catechol rings replacing the pyridone ring. From the modeling studies, the catechol analogue appeared capable of replacing one of the crystallographic waters bridging huperzine with Tyr 130 and Glu 199

Giuseppe Campiani; Alan P. Kozikowski; Shaomeng Wang; Liu Ming; Vito Nacci; Ashima Saxena; Bhupendra P

1998-01-01

123

A Rice Semi-Dwarf Gene, Tan-Ginbozu (D35), Encodes the Gibberellin Biosynthesis Enzyme, ent-Kaurene Oxidase  

Microsoft Academic Search

A rice (Oryza sativa L.) semi-dwarf cultivar, Tan-Ginbozu (d35Tan-Ginbozu), contributed to the increase in crop productivity in Japan in the 1950s. Previous studies suggested that the semi-dwarf stature of d35Tan-Ginbozu is caused by a defective early step of gibberellin biosynthesis, which is catalyzed by ent-kaurene oxidase (KO). To study the molecular characteristics of d35Tan-Ginbozu, we isolated 5 KO-like(KOL) genes from

Hironori Itoh; Tomoko Tatsumi; Tomoaki Sakamoto; Kazuko Otomo; Tomonobu Toyomasu; Hidemi Kitano; Motoyuki Ashikari; Shigeyuki Ichihara; Makoto Matsuoka

2004-01-01

124

NADPH Oxidases in Vascular Pathology  

PubMed Central

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

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

2014-01-01

125

NADPH oxidases in vascular pathology.  

PubMed

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

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

2014-06-10

126

Molecular docking of glucosamine-6-phosphate synthase in Rhizopus oryzae  

PubMed Central

Recent expansion of immunocompromised population has led to significant rise in zygomycosis caused by filamentous fungus Rhizopus oryzae. Due to emergence of fungal resistance and side-effects of antifungal drugs, there is increased demand for novel drug targets. The current study elucidates molecular interactions of peptide drugs with G-6-P synthase (catalyzing the rate-limiting step of fungal cell wall biosynthetic pathway) of R.oryzae by molecular docking studies. The PDB structures of enzyme in R.oryzae are not known which were predicted using I-TASSER server and validated with PROCHECK. Peptide inhibitors, FMDP and ADGP previously used against enzyme of E.coli (PDBid: 1XFF), were used for docking studies of enzyme in R.oryzae by SchrödingerMaestro v9.1. To investigate binding between enzyme and inhibitors, Glide and Induced Fit docking were performed. IFD results of 1XFF with FMDP yielded C1, R73, W74, T76, G99 and D123 as the binding sites. C379 and Q427 appear to be vital for binding of R.oryzae enzymes to inhibitors. The comparison results of IFD scores of enzyme in R.oryzae and E.coli (PDBid: 2BPL) yield appreciable score, hinting at the probable effectiveness of inhibitors FMDP and ADGP against R.oryzae, with ADGP showing an improved enzyme affinity. Moreover, the two copies of gene G-6-P synthase due to extensive fungal gene duplication, in R. oryzae eliminating the problem of drug ineffectiveness could act as a potential antifungal drug target in R. oryzae with the application of peptide ligands.

Banerjee, Kamalika; Gupta, Utkarsh; Gupta, Sanjay; Wadhwa, Gulshan; Gabrani, Reema; Sharma, Sanjeev Kumar; Jain, Chakresh Kumar

2011-01-01

127

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

PubMed Central

Background Substituted catechols are important precursors for large-scale synthesis of pharmaceuticals and other industrial products. Most of the reported chemical synthesis methods are expensive and insufficient at industrial level. However, biological processes for production of substituted catechols could be highly selective and suitable for industrial purposes. Results We have optimized a process for bio-catalytic production of 3-substituted catechols viz. 3-nitrocatechol (3-NC) and 3-methylcatechol (3-MC) at pilot scale. Amongst the screened strains, two strains viz. Pseudomonas putida strain (F1) and recombinant Escherichia coli expression clone (pDTG602) harboring first two genes of toluene degradation pathway were found to accumulate 3-NC and 3-MC respectively. Various parameters such as amount of nutrients, pH, temperature, substrate concentration, aeration, inoculums size, culture volume, toxicity of substrate and product, down stream extraction, single step and two-step biotransformation were optimized at laboratory scale to obtain high yields of 3-substituted catechols. Subsequently, pilot scale studies were performed in 2.5 liter bioreactor. The rate of product accumulation at pilot scale significantly increased up to ~90-95% with time and high yields of 3-NC (10 mM) and 3-MC (12 mM) were obtained. Conclusion The biocatalytic production of 3-substituted catechols viz. 3-NC and 3-MC depend on some crucial parameters to obtain maximum yields of the product at pilot scale. The process optimized for production of 3-substituted catechols by using the organisms P. putida (F1) and recombinant E. coli expression clone (pDTG602) may be useful for industrial application.

2010-01-01

128

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

PubMed

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

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

2001-10-01

129

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

PubMed Central

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

Rentero, N; Kitahama, K; Quintin, L

1993-01-01

130

Regioselectivity of catechol O-methyltransferase confers enhancement of catalytic activity  

NASA Astrophysics Data System (ADS)

Catechol O-methyltransferase (COMT) metabolizes catechol moieties by methylating a single hydroxyl group at the meta- or para- hydroxyl position. Hydrophobic amino acids near the active site of COMT influence the regioselectivity of this reaction. Our sequence analysis highlights their importance by showing that these residues are highly conserved throughout evolution. Reaction barriers calculated in the gas phase reveal a lower barrier during methylation at the meta- position, suggesting that the observed meta-regioselectivity of COMT can be attributed to the substrate itself, and that COMT has evolved residues to orient the substrate in a manner that increases the rate of catalysis.

Tsao, Douglas; Liu, Shubin; Dokholyan, Nikolay V.

2011-04-01

131

Reductive Deprotection of Silyl Groups with Wilkinson's Catalyst/Catechol Borane  

PubMed Central

Traditionally silyl groups are deprotected with acids and fluorides. These methods are, however, less discriminating when multi-silyl groups are present in the same molecule resulting in lower yields of desired products. The manipulation of these functions during the total synthesis of natural products, e.g. prostaglandins and isoprostanes, requires the selective protection and deprotection of these groups. We are reporting here on a mild, selective and efficient method for the reductive deprotection of silyl groups using Wilkinson's catalyst/catechol borane or catechol borane alone.

Patel, Pranav; Chang, Chih-Tsung; Kang, Namin; Lee, Gue-Jae; Powell, William S.; Rokach, Joshua

2007-01-01

132

Coupling in cytochrome c oxidase  

PubMed Central

Cytochrome c oxidase (ferrocytochrome c: oxygen oxidoreductase; EC 1.9.3.1) can be resolved into an electron transfer complex (ETC) and an ionophore transfer complex (ITC). Coupling requires an interaction between the moving electron in the ETC and a moving, positively charged ionophore-cation adduct in the ITC. The duplex character of cytochrome oxidase facilitates this interaction. The ITC mediates cyclical cation transport. It can be replaced as the coupling partner by the combination of valinomycin and nigericin in the presence of K+ when cytochrome oxidase is incorporated into liposomes containing acidic phospholipids or by the combination of lipid cytochrome c and bile acids in an ITC-resolved preparation of the ETC. Respiratory control can be induced by incorporating cytochrome oxidase into vesicles of unfractionated whole mitochondrial lipid. The activity of the ITC is suppressed by such incorporation and this suppression leads to the emergence of respiratory control. The ionophoroproteins of the ITC can be extracted into organic solvents; some 50% of the total protein of cytochrome oxidase is extractable. The release of free ionophore is achieved by tryptic digestion of the ionophoroprotein. Preliminary to this release the ionophoroprotein is degraded to an ionophoropeptide. Electrogenic ionophores, as well as uncoupler, are liberated by such proteolysis. The ITC contains a set of ionophoroproteins imbedded in a matrix of phospholipid. Images

Kessler, R. J.; Blondin, G. A.; Zande, H. Vande; Haworth, R. A.; Green, D. E.

1977-01-01

133

Production of bacterial blight resistant lines from somatichybridization between Oryza sativa L. and Oryza meyeriana L.*  

PubMed Central

Novel bacterial blight (BB) resistance gene(s) for rice was (were) introduced into a cultivated japonica rice variety Oryza sativa (cv. 8411), via somatic hybridization using the wild rice Oryza meyeriana as the donor of the resistance gene(s). Twenty-nine progenies of somatically hybridized plants were obtained. Seven somatically hybridized plants and their parents were used for AFLP (amplified fragment length polymorphism) analysis using 8 primer pairs. Results confirmed that these plants were somatic hybrids containing the characteristic bands of both parents. The morphology of the regenerated rice showed characters of both O. sativa and O. meyeriana. Two somatic hybrids showed highest BB resistance and the other 8 plants showed moderate resistance. The new germplasms with highest resistance have been used in the rice breeding program for the improvement of bacterial blight resistance.

Yan, Cheng-qi; Qian, Kai-xian; Xue, Gang-ping; Wu, Zhong-chang; Chen, Yue-lei; Yan, Qiu-sheng; Zhang, Xue-qing; Wu, Ping

2004-01-01

134

A proteomic study of Xanthomonas oryzae pv. oryzae in rice xylem sap.  

PubMed

Xanthomonas oryzae pv. oryzae (Xoo) is the second most important rice pathogen, causing a disease called bacterial leaf blight. Xoo colonizes and infects the vascular tissue resulting in tissue necrosis and wilting causing significant yield losses worldwide. In this study Xoo infected vascular fluid (xylem sap) was recovered and analyzed for secreted Xoo proteins. Three independent experiments resulted in the identification of 324 different proteins, 64 proteins were found in all three samples which included many of the known virulence-associated factors. In addition, 10 genes encoding for the identified proteins were inactivated and one mutant displayed statistically a significant loss in virulence when compared to the wild type Xoo, suggesting that a new virulence-associated factor has been revealed. The usefulness of this approach in understanding the lifestyle and unraveling the virulence-associated factors of phytopathogenic vascular bacteria is discussed. PMID:22835776

González, Juan F; Degrassi, Giuliano; Devescovi, Giulia; De Vleesschauwer, David; Höfte, Monica; Myers, Michael P; Venturi, Vittorio

2012-10-22

135

Relationship between glucose catabolism and xanthan production in Xanthomonas oryzae pv. oryzae.  

PubMed

Two genes involved in central carbon metabolism were inactivated to modulate intracellular glucose 6-phosphate and to evaluate its effects on xanthan production in wild-type Xanthomonas oryzae pv. oryzae. Upon the inactivation of the phosphogluconate dehydratase gene (edd), intracellular glucose 6-phosphate increased from 0.05 to 1.17 mmol/g (dry cell wt). This was accompanied by increased xanthan production of up to 2.55 g/l (culture medium). In contrast, inactivation of 6-phosphogluconate dehydrogenase gene (gndA) did not influence intracellular glucose 6-phosphate nor xanthan production. The intracellular availability of glucose 6-phosphate is proposed as a rate-limiting factor in xanthan production, and it may be possible to increases production of xanthan by modulating the activities of enzymes in central carbon metabolism. PMID:20039099

Kim, Sang-Yoon; Lee, Byoung-Moo; Cho, Jae-Yong

2010-04-01

136

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

137

Impact of Aspergillus oryzae genomics on industrial production of metabolites  

Microsoft Academic Search

Aspergillus oryzae is used extensively for the production of the traditional Japanese fermented foods sake (rice wine), shoyu (soy sauce), and miso (soybean paste). In recent years, recombinant DNA technology has been used to enhance industrial enzyme production by A. oryzae. Recently completed genomic studies using expressed sequence tag (EST) analyses and whole-genome sequencing are quickly expanding\\u000a the industrial potential

Keietsu Abe; Katusya Gomi; Fumihiko Hasegawa; Masayuki Machida

2006-01-01

138

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.

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

2013-01-01

139

Two Genomic Regions Involved in Catechol Siderophore Production by Erwinia carotovora  

PubMed Central

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

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

1994-01-01

140

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

141

Contact printing a biomimetic catecholic monolayer on a variety of surfaces and derivation reaction.  

PubMed

Biomimic catecholic "ink" is employed in surface patterning by using microcontact printing (?CP) on a variety of surfaces. The surface chemical patterning can be proofed by implementing a derivation reaction, such as specific biological recognition and surface-initiated polymerization for growth of polymer brushes. PMID:22080242

Liu, Jianxi; Ye, Qian; Yu, Bo; Wang, Xiaolong; Zhou, Feng

2012-01-11

142

Catechol Polymers for pH-Responsive, Targeted Drug Delivery to Cancer Cells  

PubMed Central

A novel cell-targeting, pH-sensitive polymeric carrier was employed in this study for delivery of the anticancer drug bortezomib (BTZ) to cancer cells. Our strategy is based on facile conjugation of BTZ to catechol-containing polymeric carriers that are designed to be taken up selectively by cancer cells through cell surface receptor-mediated mechanisms. The polymer used as a building block in this study was poly(ethylene glycol), which was chosen for its ability to reduce nonspecific interactions with proteins and cells. The catechol moiety was exploited for its ability to bind and release borate-containing therapeutics such as BTZ in a pH-dependent manner. In acidic environments, such as in cancer tissue or the subcellular endosome, BTZ dissociates from the polymer-bound catechol groups to liberate the free drug, which inhibits proteasome function. A cancer-cell-targeting ligand, biotin, was presented on the polymer carriers to facilitate targeted entry of drug-loaded polymer carriers into cancer cells. Our study demonstrated that the cancer-targeting drug–polymer conjugates dramatically enhanced cellular uptake, proteasome inhibition, and cytotoxicity toward breast carcinoma cells in comparison with nontargeting drug–polymer conjugates. The pH-sensitive catechol–boronate binding mechanism provides a chemoselective approach for controlling the release of BTZ in targeted cancer cells, establishing a concept that may be applied in the future toward other boronic acid-containing therapeutics to treat a broad range of diseases.

2011-01-01

143

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

Microsoft Academic Search

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

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

2011-01-01

144

Functional catechol- O-methyltransferase gene polymorphism and susceptibility to schizophrenia  

Microsoft Academic Search

Genetic polymorphism of catechol-O-methyltransferase (COMT), involved in the degradation of catecholamine neurotransmitters, has been investigated as a candidate for modifier of susceptibility to development of schizophrenia. To address this issue further, we carried out a study in Korean schizophrenic patients and controls. The study population consisted of 103 Korean inpatients diagnosed as schizophrenic and their 103 age and sex matched

Tae-Won Park; Kyung-Sik Yoon; Ju-Han Kim; Woong-Yang Park; Ari Hirvonen; Daehee Kang

2002-01-01

145

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

146

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

PubMed Central

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

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

2012-01-01

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

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

ERIC Educational Resources Information Center

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

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

2009-01-01

149

Integrated microfluidic device for the separation and electrochemical detection of catechol estrogen-derived DNA adducts.  

PubMed

Catechol estrogen-derived DNA adducts are formed as a result of the reaction of catechol estrogen metabolites (e.g., catechol estrogen quinones) with DNA to form depurinating adducts. Developing a new methodology for the detection of various DNA adducts is essential for medical diagnostics, and to this end, we demonstrate the applicability of on-chip capillary electrophoresis with an integrated electrochemical system for the separation and amperometric detection of various catechol estrogen-derived DNA adducts. A hybrid PDMS/glass microchip with in-channel amperometric detection interfaced with in situ palladium decoupler is utilized and presented. The influence of buffer additives along with the effect of the separation voltage on the resolving power of the microchip is discussed. Calibration plots were constructed in the range 0.4-10 ?M with r(2) ? 0.999, and detection limits in the attomole range are reported. These results suggest that on-chip analysis is applicable for analyzing various DNA adducts as potential biomarkers for future medical diagnostics. PMID:21058011

Bani-Yaseen, Abdulilah Dawoud; Kawaguchi, Toshikazu; Price, Alexander K; Culbertson, Christopher T; Jankowiak, Ryszard

2011-01-01

150

Catalytic and regiospecific extradiol cleavage of catechol by a biomimetic iron complex.  

PubMed

An iron(III)-catecholate complex of a facial tridentate ligand reacts with dioxygen in the presence of ammonium acetate-acetic acid buffer to cleave the aromatic C-C bond of 3,5-di-tert-butylcatechol regiospecifically resulting in the formation of an extradiol product with multiple turnovers. PMID:24061230

Chatterjee, Sayanti; Sheet, Debobrata; Paine, Tapan Kanti

2013-11-11

151

Characterization of NF-kB-mediated inhibition of catechol-O-methyltransferase  

Microsoft Academic Search

BACKGROUND: Catechol-O-methyltransferase (COMT), an enzyme that metabolizes catecholamines, has recently been implicated in the modulation of pain. Specifically, low COMT activity is associated with heightened pain perception and development of musculoskeletal pain in humans as well as increased experimental pain sensitivity in rodents. RESULTS: We report that the proinflammatory cytokine tumor necrosis factor ? (TNF?) downregulates COMT mRNA and protein

Inna E Tchivileva; Andrea G Nackley; Li Qian; Sean Wentworth; Matthew Conrad; Luda B Diatchenko

2009-01-01

152

Mechanisms of product formation from the pyrolytic thermal degradation of catechol.  

PubMed

Catechol has been identified as one of the most abundant organic products in tobacco smoke and a major molecular precursor for semiquinone type radicals in the combustion of biomass material. The high-temperature gas-phase pyrolysis of catechol under hydrogen-rich and hydrogen-lean conditions was studied using a fused-silica tubular flow reactor coupled to an in-line GC/MS analytical system. Thermal degradation of catechol over temperature range of 250-1000 degrees C with a reaction time of 2.0s yielded a variety products including phenol, benzene, dibenzofuran, dibenzo-p-dioxin, phenylethyne, styrene, indene, anthracene, naphthalene, and biphenylene. Ortho-benzoquinone which is typically associated with the presence of semiquinone radicals was not observed and is proposed to be the result of fast decomposition reactions that lead to a variety of other reaction products. This is in contrast to the decomposition of hydroquinone that produced para-benzoquinone as the major product. A detailed mechanism of the degradation pathway of catechol is proposed. PMID:18640699

Lomnicki, Slawomir; Truong, Hieu; Dellinger, Barry

2008-09-01

153

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

PubMed

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

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

2013-11-01

154

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

155

Isolation and characterization of rice mutants compromised in Xa21 -mediated resistance to X. oryzae pv. oryzae  

Microsoft Academic Search

The rice gene, Xa21, confers resistance to diverse races of Xanthomonas oryzae pv. oryzae (Xoo) and encodes a receptor-like kinase with leucine-rich repeats in the extra-cellular domain. To identify genes essential for the function of the Xa21 gene, 4,500 IRBB21 ( Xa21 isogenic line in IR24 background) mutants, induced by diepoxybutane and fast neutrons, were screened against Philippine race six

G. L. Wang; C. Wu; L. Zeng; C. He; M. Baraoidan; F. de Assis Goes da Silva; C. E. Williams; P. C. Ronald; H. Leung

2004-01-01

156

Stationary phase expression, purification, and characterization of XorKI, a restriction endonuclease from Xanthomonas oryzae pv. oryzae.  

PubMed

An endonuclease from Xanthomonas oryzae pathovar oryzae KACC 10331, XorKI, was heterologously produced in Escherichia coli by applying the stationary state induction method. The yield was 5.4 mg of XorKI per liter of LB medium. XorKI existed in multiple oligomeric forms as evidenced by gel filtration chromatography. The specific activity of purified XorKI was 323000 units per mg. PMID:19594434

Kang, Woo Young; Chae, Young Kee

2010-03-01

157

Effects of Metal Oxides on a Fungal Laccase Activity and Catechol Transformation  

NASA Astrophysics Data System (ADS)

The transformation of naturally occurring phenols to humic polymers is generally catalyzed by various phenoloxidases commonly present in soil. Some poorly crystalline metal oxides and hydroxides may also participate in these reactions. In this study, catechol (0.1 M) was incubated with a fungal laccase (950 unit/mL) in the presence of poorly crystalline minerals (ferrihydrite; 50 mg/mL: birnessite; 1 mg/mL: aluminum hydroxide; 50 mg/mL) to examine the interaction between these soil components under field conditions. Birnessite had an inhibitory effect on the laccase-mediated transformation of catechol (by up to 40%). Enzyme inhibition was possibly caused by the rapid production of humic-like polymers by birnessite. An additional inhibitory effect was caused by Manganese ion released from birnessite as it oxidized catechol (up to 70% loss in enzyme activity). In contrast to birnessite, aluminum hydroxide had an additive effect on the disappearance of catechol despite the rapid adsorption of the enzyme by this mineral (Xm=6.18? g/mg). Apparently, the adsorbed laccase retained some enzyme activity. Ferrihydrite also had an additive effect on catechol transformation. However, as compared to aluminum hydroxide, ferrihydrite adsorbed less laccase (Xm=0.89? g/mg) and more humic-like polymers. Unlike birnessite, aluminum hydroxide and ferrihydrite released negligible amounts of metal ions. In conclusion, under field conditions, phenoloxidase activity may be diminished by the presence of birnessite, but the presence of either ferrihydrite or aluminum hydroxide is less likely to inhibit enzyme activity, and may even enhance substrate transformation.

Ahn, M.; Dec, J.; Bollag, J.

2003-12-01

158

NADPH oxidases: progress and opportunities.  

PubMed

Abstract From the initial discovery in 1999 that NADPH oxidases comprise a family of enzymes to our current focus on drug development to treat multiple pathologies related to this enzyme family, progress has been swift and impressive. We have expanded our understanding of the extent of the family, the basic enzymatic biochemistry, the multiple cellular functions controlled by NADPH oxidases, and their varied roles in physiology and diseases. We have developed numerous cell culture tools, animal models, and human databases that have allowed us to delve deeply into the various roles of these enzymes. However, it is clear that much remains to be learned and that there are many opportunities for new tools and new research directions to more fully understand these critical enzymes. With this Antioxidants and Redox Signaling Forum, we explore in detail the progress, challenges, and opportunities in Nox biology. Progress so far has clearly shown that NADPH oxidases are integral to fully functioning organisms and that the dysregulation of Nox enzymes contributes to a wide variety of pathologies. We have the opportunity to develop new tools and small molecules that will not only help us to better understand the molecular underpinnings of NADPH oxidases but also to develop treatments for diverse human diseases. Antioxid. Redox Signal. 20, 2692-2694. PMID:24730700

San Martin, Alejandra; Griendling, Kathy K

2014-06-10

159

Identification and molecular characterization of twin-arginine translocation system (Tat) in Xanthomonas oryzae pv. oryzae strain PXO99.  

PubMed

Xanthomonas oryzae pv. oryzae causes bacterial leaf blight, one of the most widespread and destructive bacterial diseases in rice. This study identified and characterized the contribution of the twin-arginine translocation (Tat) pathway to motility, chemotaxis, extracellular polysaccharide (EPS) production and virulence in X. oryzae pv. oryzae strain PXO99. The tatC disruption mutant (strain TCM) of strain PXO99 were generated, and confirmed both by PCR and Southern blotting. Strain PXO99 cells were highly motile in NYGB 0.3% soft agar plate. In contrast, the tatC mutation impaired motility. Furthermore, strain TCM cells lacked detectable flagella and exhibited almost no chemotaxis toward glucose under aerobic conditions, indicating that the Tat secretion pathway contributed to flagellar biogenesis and chemotactic responses. It was also observed that strain TCM exhibited a reductive production of extracellular polysaccharide (EPS) and a significant reduction of virulence on rice plants when compared with the wild type PXO99. However, the tatC mutation in strain PXO99 did not affect growth rate and the ability to induce hypersensitive response (HR) in nonhost tobacco (Nicotiana tabacum L. cv. Samsun). Our findings indicated that the Tat system of X. oryzae pv. oryzae played an important role in the pathogen's virulence. PMID:18998110

Chen, Lei; Hu, Baishi; Qian, Guoliang; Wang, Chen; Yang, Wanfeng; Han, Zhicheng; Liu, Fengquan

2009-02-01

160

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

161

Chromosomal polymorphism of ribosomal genes in the genus Oryza  

PubMed Central

The genes encoding for 18S–5.8S–28S ribosomal RNA (rDNA) are both conserved and diversified. We used rDNA as probe in the fluorescent in situ hybridization (rDNA-FISH) to localized rDNAs on chromosomes of 15 accessions representing ten Oryza species. These included cultivated and wild species of rice, and four of them are tetraploids. Our results reveal polymorphism in the number of rDNA loci, in the number of rDNA repeats, and in their chromosomal positions among Oryza species. The numbers of rDNA loci varies from one to eight among Oryza species. The rDNA locus located at the end of the short arm of chromosome 9 is conserved among the genus Oryza. The rDNA locus at the end of the short arm of chromosome 10 was lost in some of the accessions. In this study, we report two genome specific rDNA loci in the genus Oryza. One is specific to the BB genome, which was localized at the end of the short arm of chromosome 4. Another may be specific to the CC genome, which was localized in the proximal region of the short arm of chromosome 5. A particular rDNA locus was detected as stretched chromatin with bright signals at the proximal region of the short arm of chromosome 4 in O.grandiglumis by rDNA-FISH. We suggest that chromosomal inversion and the amplification and transposition of rDNA might occur during Oryza species evolution. The possible mechanisms of cyto-evolution in tetraploid Oryza species are discussed.

Lee, Yung-I; Cheng, Yueh-Yun; Chou, Yi-Jia; Lu, Chia-Fu

2008-01-01

162

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

PubMed Central

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

2010-01-01

163

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

PubMed

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

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

2013-01-01

164

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

PubMed

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

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

2014-07-01

165

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.

Zhao, Guozhong; Yao, Yunping; Hou, Lihua

2014-01-01

166

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

PubMed

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; Wang, Chunling; Cao, Xiaohong

2014-01-01

167

Characterization of Two Brassinosteroid C-6 Oxidase Genes in Pea1[W][OA  

PubMed Central

C-6 oxidation genes play a key role in the regulation of biologically active brassinosteroid (BR) levels in the plant. They control BR activation, which involves the C-6 oxidation of 6-deoxocastasterone (6-DeoxoCS) to castasterone (CS) and in some cases the further conversion of CS to brassinolide (BL). C-6 oxidation is controlled by the CYP85A family of cytochrome P450s, and to date, two CYP85As have been isolated in tomato (Solanum lycopersicum), two in Arabidopsis (Arabidopsis thaliana), one in rice (Oryza sativa), and one in grape (Vitis vinifera). We have now isolated two CYP85As (CYP85A1 and CYP85A6) from pea (Pisum sativum). However, unlike Arabidopsis and tomato, which both contain one BR C-6 oxidase that converts 6-DeoxoCS to CS and one BR C-6 Baeyer-Villiger oxidase that converts 6-DeoxoCS right through to BL, the two BR C-6 oxidases in pea both act principally to convert 6-DeoxoCS to CS. The isolation of these two BR C-6 oxidation genes in pea highlights the species-specific differences associated with C-6 oxidation. In addition, we have isolated a novel BR-deficient mutant, lke, which blocks the function of one of these two BR C-6 oxidases (CYP85A6). The lke mutant exhibits a phenotype intermediate between wild-type plants and previously characterized pea BR mutants (lk, lka, and lkb) and contains reduced levels of CS and increased levels of 6-DeoxoCS. To date, lke is the only mutant identified in pea that blocks the latter steps of BR biosynthesis and it will therefore provide an excellent tool to further examine the regulation of BR biosynthesis and the relative biological activities of CS and BL in pea.

Jager, Corinne E.; Symons, Gregory M.; Nomura, Takahito; Yamada, Yumiko; Smith, Jennifer J.; Yamaguchi, Shinjiro; Kamiya, Yuji; Weller, James L.; Yokota, Takao; Reid, James B.

2007-01-01

168

Multiple adhesin-like functions of Xanthomonas oryzae pv. oryzae are involved in promoting leaf attachment, entry, and virulence on rice.  

PubMed

Xanthomonas oryzae pv. oryzae is the causal agent of bacterial blight of rice. We have used enhanced green fluorescent protein-tagged X. oryzae pv. oryzae cells in conjunction with confocal microscopy to monitor the role of several adhesin-like functions in bacterial adhesion to leaf surface and early stages of leaf entry. Mutations in genes encoding either the Xanthomonas adhesin-like protein A (XadA) or its paralog, Xanthomonas adhesin-like protein B (XadB), as well as the X. oryzae pv. oryzae homolog of Yersinia autotransporter-like protein H (YapH), exhibit deficiencies in leaf attachment or entry. A mutation in the X. oryzae pv. oryzae pilQ gene, which is predicted to encode the type IV pilus secretin, appears to have no effect on leaf attachment or entry. The xadA- mutant is deficient in the ability to cause disease following surface inoculation while the XadB, YapH, and PilQ functions are less important than XadA for this process. The xadA- and xadB- mutants have no effect on virulence following wound inoculation whereas the yapH- and pilQ- mutants are always virulence deficient following wound inoculation. Overall, these results indicate that multiple adhesin-like functions are involved in promoting virulence of X. oryzae pv. oryzae, with preferential involvement of individual functions at different stages of the disease process. PMID:19061404

Das, Amit; Rangaraj, Nandini; Sonti, Ramesh V

2009-01-01

169

Polyphenol oxidase from wheat bran is a serpin.  

PubMed

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

Yamasaki, Yoshiki; Konno, Haruyoshi; Noda, Kazuhiko

2008-01-01

170

Trichoderma harzianum: a biocontrol agent against Bipolaris oryzae.  

PubMed

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

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

2007-08-01

171

Cloning and Nucleotide Sequence of Catechol 2,3Dioxygenase Gene from the Naphthalene-Degrading Pseudomonas putida NA3  

Microsoft Academic Search

Pseudomonas putida strain NA3 was found to degrade naphthalene very efficiently and use it as a main carbon and energy source to support its growth. Naphthalene was found to be metabolized via the extradiol meta ring-cleavage pathway. Catechol 2,3-dioxygenase was found to be the responsible key enzyme for the dearomatization of naphthalene. Catechol 2,3- dioxygenase gene from the naphthalene-degrading P.

MOHAMED KHALED IBRAHIM

172

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

173

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

PubMed

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

Chern, Mawsheng; Bai, Wei; Chen, Xuewei; Canlas, Patrick E; Ronald, Pamela C

2013-01-01

174

A new diketopiperazine alkaloid from Aspergillus oryzae.  

PubMed

Investigation of bioactive secondary metabolites from terrestrial Aspergillus oryzae sp. MMAO1 using M2 medium afforded a new diketopiperazine alkaloid, 7,9-dihydroxy-3-(1H-indol-3-ylmethyl)-8-methoxy-2,3,11,11a-tetrahydro-6H-pyrazino[1,2-b]isoquinoline-1,4-dione (1a), containing the unusual amino acid L-6,8-dihydroxy-7-methoxyphenylalanine. This was co-isolated with ditryptophenaline (2), cyclo-(Tryp,Tyr) (4), cyclo-(Pro,Val), ?-cyclopiazonic acid (3), kojic acid and uridine. Re-cultivation of the fungal strain on Dox medium led to the production of bisdethio(bismethylthio)gliotoxin (5), pseurotin A (6) along with linoleic acid, ?-cyclopiazonic acid (3) and kojic acid. The chemical structure of the new diketopiperazine alkaloid including the relative configuration was determined by 1D and 2D NMR spectroscopy and HR-ESI-MS spectrometry, and by comparison with the related literature. The new alkaloid (1a) showed no antimicrobial activity or cytotoxicity against brine shrimps. PMID:24116376

Shaaban, Mohamed; El-Metwally, Mohammad Magdy; Nasr, Hamdi

2014-01-01

175

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

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

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

PubMed Central

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

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

2012-01-01

178

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

Microsoft Academic Search

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

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

2005-01-01

179

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

180

Differential Requirement of Oryza sativa RAR1 in Immune Receptor-Mediated Resistance of Rice to Magnaporthe oryzae  

PubMed Central

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

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

2013-01-01

181

Coordination chemistry of microbial iron transport compounds. IX. Stability constants for catechol models of enterobactin  

Microsoft Academic Search

The stability constants of ferric complexes with several substituted catechol (1,2-dihydroxybenzene) ligands in aqueous solutions of low ionic strength have been determined at 27°C in the pH range 2 to 11. Enterobactin, the principal siderophore of enteric bacteria, is a tricatechol and, from the formation constants reported here, is estimated to have a formation constant with ferric ion which is

Alex Avdeef; Stephen R. Sofen; Thomas L. Bregante; Kenneth N. Raymond

1978-01-01

182

Ultrastable iron oxide nanoparticle colloidal suspensions using dispersants with catechol-derived anchor groups.  

PubMed

We have found catechol-derivative anchor groups which possess irreversible binding affinity to iron oxide and thus can optimally disperse superparamagnetic nanoparticles under physiologic conditions. This not only leads to ultrastable iron oxide nanoparticles but also allows close control over the hydrodynamic diameter and interfacial chemistry. The latter is a crucial breakthrough to assemble functionalized magnetic nanoparticles, e.g., as targeted magnetic resonance contrast agents. PMID:19835370

Amstad, Esther; Gillich, Torben; Bilecka, Idalia; Textor, Marcus; Reimhult, Erik

2009-12-01

183

Activity of catechol-O-methyltransferase in brain regions and adrenal gland during the oestrus cycle  

Microsoft Academic Search

Summary The activity of the enzyme catechol-O-methyltransferase (COMT) during four different phases of the oestrus cycle were determined. Brain and hypothalamus had highest level of COMT activity during oestrus phase, while at pro-oestrus it was at its lowest level. COMT activity in the adrenal gland was also modified during the four phases with the maximum level at met-oestrus and the

S. Parvez; G. Ismahan; A. Raza-Bukhari; M. B. H. Youdim

1978-01-01

184

Catecholate receptor proteins in Salmonella enterica: role in virulence and implications for vaccine development  

Microsoft Academic Search

Three outer membrane proteins of Salmonella enterica serovar Typhimurium function as catecholate siderophore receptors. IroN promotes uptake of enterobactin, salmochelins and 2,3-dihydroxybenzoylserine, FepA transports enterobactin and 2,3-dihydroxybenzoylserine, and Cir is a receptor for 2,3-dihydroxybenzoylserine. In addition, all three proteins are required for l-norepinephrine-facilitated iron uptake from transferrin as judged by failure of a fepA iroN cir triple mutant to grow

P. H. Williams; W. Rabsch; U. Methner; W. Voigt; H. Tschäpe; R. Reissbrodt

2006-01-01

185

Association study of a functional catechol- O-methyltransferase gene polymorphism in Japanese schizophrenics  

Microsoft Academic Search

Catechol-O-methyltransferase (COMT) is an enzyme which inactivates catecholamine neurotransmitters by methylation, and is considered a candidate for involvement in schizophrenia. A functional COMT gene polymorphism influencing the enzyme activities, the high activity (val-108) and the low activity allele (met-108), was recently confirmed. We investigated a genetic association between schizophrenia and the COMT gene polymorphism in 150 Japanese schizophrenics and controls.

Osamu Ohmori; Takahiro Shinkai; Hideki Kojima; Takeshi Terao; Takashi Suzuki; Takashi Mita; Kazuhiko Abe

1998-01-01

186

Significance of catechol-O-methyltransferase gene polymorphism in fibromyalgia syndrome  

Microsoft Academic Search

Fibromyalgia syndrome (FS) is associated with a neuroendocrinal disorder characterized by abnormal function of the hypothalamic-pituitary-adrenal (HPA) axis, including hyperactive adrenocorticotropic hormone (ACTH) release and adrenal hyporesponsiveness. Catechol-O-methyltransferase (COMT) enzyme inactivates catecholamines and catecholamine-containing drugs. Polymorphism in the gene encodes for the COMT enzyme. For this study, the significance of COMT polymorphism was assessed in FS. There were three polymorphisms

Sava? Gürsoy; Emin Erdal; Hasan Herken; Ercan Madenci; Belgin Ala?ehirli; Nurten Erdal

2003-01-01

187

Association Analysis of a Functional Catechol-O-Methyltransferase Gene Polymorphism in Schizophrenic Patients in Taiwan  

Microsoft Academic Search

The catechol-O-methyltransferase (COMT) gene was thought to be a candidate gene for schizophrenia because of its role in inactivating dopamine. This study examined the relationship between a functional polymorphism (val158met) of the COMT gene, schizophrenia and its associated behaviors. One hundred and ninety-eight Chinese schizophrenic patients and 188 controls were genotyped by polymerase chain reaction restriction fragment length polymorphism. Of

Ying-Jay Liou; Shih-Jen Tsai; Chen-Jee Hong; Ying-Chieh Wang; I-Ching Lai

2001-01-01

188

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

Microsoft Academic Search

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

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

2005-01-01

189

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

Microsoft Academic Search

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

R. Z. Hinrichs; L. A. Woodill

2009-01-01

190

Attention-deficit\\/hyperactivity disorder phenotype is influenced by a functional catechol- O -methyltransferase variant  

Microsoft Academic Search

The catechol-O-methyltransferase gene (COMT) plays a crucial role in the metabolism of catecholamines in the frontal cortex. A single nucleotide polymorphism (Val158Met SNP, rs4680) leads to either methionine (Met) or valine (Val) at codon 158, resulting in a three- to fourfold reduction\\u000a in COMT activity. The aim of the present study was to assess the COMT Val158Met SNP as a

Haukur Pálmason; Dirk Moser; Jessica Sigmund; Christian Vogler; Susann Hänig; Anna Schneider; Christiane Seitz; Alexander Marcus; Jobst Meyer; Christine M. Freitag

2010-01-01

191

Catechol O-methyltransferase pharmacogenomics and selective serotonin reuptake inhibitor response  

Microsoft Academic Search

We applied a systematic pharmacogenetic approach to investigate the role of genetic variation in the gene encoding catechol O-methyltransferase (COMT) in individual variation in selective serotonin reuptake inhibitor (SSRI) response among depressed patients. In all, 23 single-nucleotide polymorphisms (SNPs) in COMT were genotyped using DNA from the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study (N=1914). One SNP, rs13306278, located

Y Ji; J Biernacka; K Snyder; M Drews; L L Pelleymounter; C Colby; L Wang; D A Mrazek; R M Weinshilboum

2012-01-01

192

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

Microsoft Academic Search

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

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

2007-01-01

193

Influence of catechol-O-methyltransferase (COMT) gene polymorphisms in pain sensibility of Brazilian fibromialgia patients  

Microsoft Academic Search

Fibromyalgia syndrome (FS) is a rheumatic syndrome affecting to 2–3% of individuals of productive age, mainly women. Neuroendocrine\\u000a and genetic factors may play a significant role in development of the disease which is characterized by diffuse chronic pain\\u000a and presence of tender points. Several studies have suggested an association between FS, especially pain sensitivity, and polymorphism of the catechol-O-methyltransferase\\u000a (COMT)

Flávia Regina Barbosa; Josie Budag Matsuda; Mendelson Mazucato; Suzelei de Castro França; Sônia Marli Zingaretti; Lucienir Maria da Silva; Nilce Maria Martinez-Rossi; Milton Faria Júnior; Mozart Marins; Ana Lúcia Fachin

194

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

Microsoft Academic Search

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

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

2002-01-01

195

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

Microsoft Academic Search

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

Gaëlle Carré de Lusançay; Sophie Norvez; Ilias Iliopoulos

2010-01-01

196

Incorporation of copper into lysyl oxidase.  

PubMed Central

Lysyl oxidase is a copper-dependent enzyme involved in extracellular processing of collagens and elastin. Although it is known that copper is essential for the functional activity of the enzyme, there is little information on the incorporation of copper. In the present study we examined the insertion of copper into lysyl oxidase using 67Cu in cell-free transcription/translation assays and in normal skin fibroblast culture systems. When a full-length lysyl oxidase cDNA was used as a template for transcription/translation reactions in vitro, unprocessed prolysyl oxidase appeared to bind copper. To examine further the post-translational incorporation of copper into lysyl oxidase, confluent skin fibroblasts were incubated with inhibitors of protein synthesis (cycloheximide, 10 microg/ml), glycosylation (tunicamycin, 10 microg/ml), protein secretion (brefeldin A, 10 microg/ml) and prolysyl oxidase processing (procollagen C-peptidase inhibitor, 2.5 microg/ml) together with 300 microCi of carrier-free 67Cu. It was observed that protein synthesis was a prerequisite for copper incorporation, but inhibition of glycosylation by tunicamycin did not affect the secretion of 67Cu as lysyl oxidase. Brefeldin A inhibited the secretion of 67Ci-labelled lysyl oxidase by 46%, but the intracellular incorporation of copper into lysyl oxidase was not affected. In addition, the inhibition of the extracellular proteolytic processing of prolysyl oxidase to lysyl oxidase had minimal effects on the secretion of protein-bound 67Cu. Our results indicate that, similar to caeruloplasmin processing [Sato and Gitlin (1991) J. Biol. Chem. 266, 5128-5134], copper is inserted into prolysyl oxidase independently of glycosylation.

Kosonen, T; Uriu-Hare, J Y; Clegg, M S; Keen, C L; Rucker, R B

1997-01-01

197

Dietary inhibitors of monoamine oxidase A  

Microsoft Academic Search

Inhibition of monoamine oxidase is one way to treat depression and anxiety. The information now available on the pharmacokinetics\\u000a of flavonoids and of the components of tobacco prompted an exploration of whether a healthy diet (with or without smoking)\\u000a provides active compounds in amounts sufficient to partially inhibit monoamine oxidase. A literature search was used to identify\\u000a dietary monoamine oxidase

Sarah E. Dixon Clarke; Rona R. Ramsay

2011-01-01

198

Electrochemical oxidation of hydroquinone, resorcinol, and catechol on boron-doped diamond anodes.  

PubMed

The electrochemical oxidation of aqueous wastes polluted with hydroquinone, resorcinol, or catechol on boron-doped diamond electrodes has been studied. The complete mineralization of the organic waste has been obtained independently of the nature of each isomer. No aromatic intermediates were found during the treatment, and solely aliphatic intermediates (carboxylic acids C4 and C2, mainly) were detected in the three cases. Although as from the bulk electrolyses study no differences in the electrochemical oxidation of dihydroxybenzenes seem to exist, different voltammetric behavior between resorcinol and the other two isomers was obtained in the voltammetric study. Catechol and hydroquinone have a reversible quinonic form, and a cathodic reduction peak appears in their voltammograms. The characterization of the first steps in the electrochemical oxidation of the three dihydroxybenzenes showed the formation of a larger number of intermediates in the oxidation of catechol, although no carbon dioxide was detected in its oxidation. Conversely, the oxidation of resorcinol and hydroquinone lead to the formation of important concentrations of carbon dioxide. The nondetection of aromatic intermediates, even if small quantities of charge are passed, confirms that the oxidation must be carried out directly on the electrode surface or by hydroxyl radicals generated by decomposition of water. PMID:16201653

Nasr, Bensalah; Abdellatif, Gadri; Cańizares, Pablo; Sáez, Cristina; Lobato, Justo; Rodrigo, Manuel A

2005-09-15

199

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

200

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

PubMed Central

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

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

2012-01-01

201

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

PubMed

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

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

2013-01-14

202

Serotonin-induced hypersensitivity via inhibition of catechol O-methyltransferase activity.  

PubMed

The subcutaneous and systemic injection of serotonin reduces cutaneous and visceral pain thresholds and increases responses to noxious stimuli. Different subtypes of 5-hydroxytryptamine (5-HT) receptors are suggested to be associated with different types of pain responses. Here we show that serotonin also inhibits catechol O-methyltransferase (COMT), an enzyme that contributes to modultion the perception of pain, via non-competitive binding to the site bound by catechol substrates with a binding affinity comparable to the binding affinity of catechol itself (K(i)?=?44 ?M). Using computational modeling, biochemical tests and cellular assays we show that serotonin actively competes with the methyl donor S-adenosyl-L-methionine (SAM) within the catalytic site. Binding of serotonin to the catalytic site inhibits the access of SAM, thus preventing methylation of COMT substrates. The results of in vivo animal studies show that serotonin-induced pain hypersensitivity in mice is reduced by either SAM pretreatment or by the combined administration of selective antagonists for ?(2)- and ?(3)-adrenergic receptors, which have been previously shown to mediate COMT-dependent pain signaling. Our results suggest that inhibition of COMT via serotonin binding contributes to pain hypersensitivity, providing additional strategies for the treatment of clinical pain conditions. PMID:22500608

Tsao, Douglas; Wieskopf, Jeffrey S; Rashid, Naim; Sorge, Robert E; Redler, Rachel L; Segall, Samantha K; Mogil, Jeffrey S; Maixner, William; Dokholyan, Nikolay V; Diatchenko, Luda

2012-01-01

203

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

PubMed

In the present paper, the removal of aniline by adsorption process onto granular activated carbon (GAC) is reported from aqueous solutions containing catechol and resorcinol separately. The Taguchi experimental design was applied to study the effect of such parameters as the initial component concentrations (C(0,i)) of two solutes (aniline and catechol or aniline and resorcinol) in the solution, temperature (T), adsorbent dosage (m) and contact time (t). The L27 orthogonal array consisting of five parameters each with three levels was used to determine the total amount of solutes adsorbed on GAC (q(tot), mmol/g) and the signal-to-noise ratio. The analysis of variance (ANOVA) was used to determine the optimum conditions. Under these conditions, the ANOVA shows that m is the most important parameter in the adsorption process. The most favourable levels of process parameters were T = 303 K, m = 10 g/l and t = 660 min for both the systems, qtot values in the confirmation experiments carried out at optimum conditions were 0.73 and 0.95 mmol/g for aniline-catechol and aniline-resorcinol systems, respectively. PMID:22720400

Suresh, S; Srivastava, V C; Mishrab, I M

2012-01-01

204

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

PubMed

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

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

2014-07-15

205

Cyclopiazonic acid biosynthesis of Aspergillus flavus and Aspergillus oryzae.  

PubMed

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

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

2009-12-01

206

Effects of the co-carcinogen catechol on benzo(a)pyrene metabolism and DNA adduct formation in mouse skin  

SciTech Connect

We have studied the effects of the co-carcinogen catechol (1,2-dihydroxybenzene) on the metabolic activation of (/sup 3/H) benzo(a)pyrene (BaP) in mouse skin, in vivo and on the binding of BaP metabolites to DNA and protein at intervals from 0.5-24 h. Upon topical application of 0.015 mg (/sup 3/H)BaP and 0.25 or 0.5 mg catechol per mouse, catechol had little effect on the total amount of (/sup 3/H)BaP metabolized in mouse skin, but it affected the relative proportions of (/sup 3/H)BaP metabolites. Catechol (0.5 mg/mouse) decreased the proportion of water-soluble (/sup 3/H)BaP metabolites, ethyl acetate-soluble polar metabolites and quinones, but doubled the levels of unconjugated 3-hydroxy-BaP at all measured intervals after treatment. Catechol also caused a small increase in the levels of trans-7,8-dihydroxy-7,8-dihydroBaP and trans-9,10-dihydroxy-9,10-dihydroBaP 0.5 h after treatment. Two hours after treatment, the levels of these metabolites subsided to those of the controls. Catechol did not affect the levels of glutathione conjugates of BaP. However, it caused a decrease in glucuronide and sulphate conjugate formation from BaP. Catechol caused an approximately 2-fold increase in the formation of anti-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydroBaP (BPDE) DNA adducts and elevated the ratio of anti-syn-BPDE-DNA adducts 1.6 to 2.9-fold. Catechol treatment increased the radioactivity associated with epidermal proteins after (/sup 3/H)BaP application. Because catechol increased levels of 3-hydroxyBaP, we considered the possibility that 3-hydroxyBaP might enhance the tumor initiating activities of BaP or BPDE in mouse skin; a bioassay demonstrated that this was not the case. The results of this study indicate that one important effect of catechol related to its co-carcinogenicity is its ability to enhance formation of anti-BPDE-DNA adducts in mouse skin.

Melikian, A.A.; Leszczynska, J.M.; Hecht, S.S.; Hoffmann, D.

1986-01-01

207

Bioactive steroids from Oryza sativa L.  

PubMed

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

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

2006-07-01

208

Long terminal repeat retrotransposons of Oryza sativa  

PubMed Central

Background Long terminal repeat (LTR) retrotransposons constitute a major fraction of the genomes of higher plants. For example, retrotransposons comprise more than 50% of the maize genome and more than 90% of the wheat genome. LTR retrotransposons are believed to have contributed significantly to the evolution of genome structure and function. The genome sequencing of selected experimental and agriculturally important species is providing an unprecedented opportunity to view the patterns of variation existing among the entire complement of retrotransposons in complete genomes. Results Using a new data-mining program, LTR_STRUC, (LTR retrotransposon structure program), we have mined the GenBank rice (Oryza sativa) database as well as the more extensive (259 Mb) Monsanto rice dataset for LTR retrotransposons. Almost two-thirds (37) of the 59 families identified consist of copia-like elements, but gypsy-like elements outnumber copia-like elements by a ratio of approximately 2:1. At least 17% of the rice genome consists of LTR retrotransposons. In addition to the ubiquitous gypsy- and copia-like classes of LTR retrotransposons, the rice genome contains at least two novel families of unusually small, non-coding (non-autonomous) LTR retrotransposons. Conclusions Each of the major clades of rice LTR retrotransposons is more closely related to elements present in other species than to the other clades of rice elements, suggesting that horizontal transfer may have occurred over the evolutionary history of rice LTR retrotransposons. Like LTR retrotransposons in other species with relatively small genomes, many rice LTR retrotransposons are relatively young, indicating a high rate of turnover.

McCarthy, Eugene M; Liu, Jingdong; Lizhi, Gao; McDonald, John F

2002-01-01

209

Crystallization and preliminary crystallographic studies of CbsA, a secretory exoglucanase from Xanthomonas oryzae pv. oryzae.  

PubMed

The bacterial pathogen Xanthomonas oryzae pv. oryzae causes bacterial leaf blight, a serious disease of rice. The secreted exoglucanase CbsA is an important virulence factor of this pathogen. It belongs to the glycosyl hydrolase 6 family of proteins based on the carbohydrate-active enzyme (CAZY) classification. In this study, CbsA has been overexpressed, purified and crystallized. The crystal diffracted to a resolution of 1.86?Ĺ and belonged to space group P2(1)2(1)2(1). It contained one monomer per asymmetric unit, with a solvent content of 45.8%. PMID:23027745

Kumar, Sushil; Haque, Asfarul S; Jha, Gopaljee; Sonti, Ramesh V; Sankaranarayanan, Rajan

2012-10-01

210

Effect of modified glucose catabolism on xanthan production in Xanthomonas oryzae pv. oryzae.  

PubMed

In this study, the glucose 6-phosphate dehydrogenase gene (XOO2314) was inactivated in order to modulate the intracellular glucose 6-phosphate, and its effects on xanthan production in a wild-type strain of Xanthomonas oryzae were evaluated. The intracellular glucose 6-phosphate was increased from 17.6 to 99.4 ?mol g?ą (dry cell weight) in the gene-disrupted mutant strain. The concomitant increase in the glucose 6-phosphate was accompanied by an increase in xanthan production of up to 2.23 g l?ą (culture medium). However, in defined medium supplemented with 0.4% glucose, the growth rate of the mutant strain was reduced to 52.9% of the wild-type level. Subsequently, when a family B ATP-dependent phosphofructokinase from Escherichia coli was overexpressed in the mutant strain, the growth rate was increased to 142.9%, whereas the yields of xanthan per mole of glucose remained approximately the same. PMID:22075924

Jang, Se-Gul; Lee, Byoung-Moo; Cho, Jae-Yong

2012-04-01

211

Cellular oligomerization of alpha-synuclein is determined by the interaction of oxidized catechols with a C-terminal sequence.  

PubMed

The mechanisms that govern the formation of alpha-synuclein (alpha-syn) aggregates are not well understood but are considered a central event in the pathogenesis of Parkinson's disease (PD). A critically important modulator of alpha-syn aggregation in vitro is dopamine and other catechols, which can prevent the formation of alpha-syn aggregates in cell-free and cellular model systems. Despite the profound importance of this interaction for the pathogenesis of PD, the processes by which catechols alter alpha-syn aggregation are unclear. Molecular and biochemical approaches were employed to evaluate the mechanism of catechol-alpha-syn interactions and the effect on inclusion formation. The data show that the intracellular inhibition of alpha-syn aggregation requires the oxidation of catechols and the specific noncovalent interaction of the oxidized catechols with residues (125)YEMPS(129) in the C-terminal region of the protein. Cell-free studies using novel near infrared fluorescence methodology for the detection of covalent protein-ortho-quinone adducts showed that although covalent modification of alpha-syn occurs, this does not affect alpha-syn fibril formation. In addition, oxidized catechols are unable to prevent both thermal and acid-induced protein aggregation as well as fibrils formed from a protein that lacks a YEMPS amino acid sequence, suggesting a specific effect for alpha-syn. These results suggest that inappropriate C-terminal cleavage of alpha-syn, which is known to occur in vivo in PD brain or a decline of intracellular catechol levels might affect disease progression, resulting in accelerated alpha-syn inclusion formation and dopaminergic neurodegeneration. PMID:17785456

Mazzulli, Joseph R; Armakola, Maria; Dumoulin, Michelle; Parastatidis, Ioannis; Ischiropoulos, Harry

2007-10-26

212

Impacts of surface adsorbed catechol on tropospheric aerosol surrogates: heterogeneous ozonolysis and its effects on water uptake.  

PubMed

Surface adsorbed organics are ubiquitous components of inorganic tropospheric aerosols and have the potential to alter aerosol chemical and physical properties. To assess the impact of adsorbed organics on water uptake by inorganic substrates, we used diffuse reflectance infrared spectroscopy to compared water adsorption isotherms for uncoated NaCl and ?-Al2O3 samples, samples containing a monolayer of adsorbed catechol, and adsorbed catechol samples following ozonolysis. Adsorption of gaseous catechol on to the inorganic substrates produced vibrational features indicating physisorption on NaCl and displacement of surface hydroxyl groups forming binuclear bidentate catecholate on ?-Al2O3, with surface concentrations of 2-3 × 10(18) molecules m(-2). Subsequent heterogeneous ozonolysis produced muconic acid at a rate 4-5 times faster on NaCl compared to ?-Al2O3, with predicted atmospheric lifetimes of 4.3 and 18 h, respectively, assuming a tropospheric ozone concentration of 40 ppb. Water adsorption isotherms for all NaCl samples were indistinguishable within experimental uncertainty, indicating that these organic monolayers had negligible impact on coadsorbed water surface concentrations for these systems. ?-Al2O3-catechol samples exhibited dramatically less water uptake compared to uncoated ?-Al2O3, while oxidation of surface adsorbed catechol had no effect on the extent of water uptake. For both substrates, adsorbed organics increased the relative abundance of "ice-like" versus "liquid-like" water, with the effect larger for catechol than oxidized ozonolysis products. These results highlight the importance of aerosol substrate in understanding the heterogeneous ozonolysis of adsorbed polyphenols and suggest such coatings may impair ice nucleation by aluminosilicate mineral aerosol. PMID:23782312

Woodill, Laurie A; O'Neill, Erinn M; Hinrichs, Ryan Z

2013-07-11

213

Photoreactions of cytochrome C oxidase.  

PubMed

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

Winterle, John S; Einarsdóttir, Olöf

2006-01-01

214

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

215

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

216

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

217

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

218

Identification of copper ligands in Aspergillus oryzae tyrosinase by site-directed mutagenesis.  

PubMed

Copper ligands of the recombinant tyrosinase from the fungus Aspergillus oryzae expressed in Saccharomyces cerevisiae or Escherichia coli were identified by site-directed mutagenesis. The recombinant protyrosinases expressed in S. cerevisiae were assayed for catalytic activities of mono-oxygenase and L-dopa oxidase at pH 5.5 after acid shock at pH 3.0. Replacements of His-63, His-84, His-93, His-290, His-294, His-332 or His-333 with asparagine resulted in mutant enzymes exhibiting no activities. The site-directed mutant Cys82Ala showed that Cys-82 was also an essential residue for the activity. We obtained homogeneous preparations of activated tyrosinases from mutated thioredoxin fusion gene products expressed in E. coli by acid shock. The copper contents of engineered mutants and wild-type enzyme expressed in E. coli were determined by atomic absorption spectrophotometry. The wild-type enzyme contained 2 g-atoms of copper/mol of the subunit. The His63Asn, His84Asn, His93Asn, His290Asn, His294Asn, His332Asn, His333Asn or Cys82Ala substitution decreased copper binding by approx. 50%, indicating that the mutants contain only approx. 1 g-atom of copper/mol of the subunit. The five mutants His63Asn, His93Asn, His290Asn, His294Asn and Cys82Ala contain only one copper ion, which is fully detectable by EPR. From the correlation of g( parallel) and (Cu)A( parallel), we deduced that the nitrogen or sulphur donors in the copper ligands should be in a square or a distorted tetrahedral geometric environment. In further atomic absorption spectrophotometry experiments, no copper atom was observed in the seven double mutants His63Asn/His290Asn, His63Asn/His294Asn, His63Asn/His332Asn, His63Asn/His333Asn, Cys82Ala/His290Asn, His84Asn/His333Asn and His93Asn/His290Asn. We propose a new structure of active sites of tyrosinase from A. oryzae: the most likely binding sites of tyrosinase for Cu(A) are His-63, His-84 and His-93, with the remaining conserved Cys-82 providing the fourth ligand. Cu(B) liganded by four histidine residues, His-290, His-294, His-332 and His-333, is identified as new binding motif of Cu(B). PMID:10947969

Nakamura, M; Nakajima, T; Ohba, Y; Yamauchi, S; Lee, B R; Ichishima, E

2000-09-01

219

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

220

Hyperuricemia and xanthine oxidase in preeclampsia, revisited  

Microsoft Academic Search

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

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

1996-01-01

221

Biomineralization mechanism of gold by zygomycete fungi Rhizopus oryzae.  

PubMed

In recent years, there has been significant progress in the biological synthesis of nanomaterials. However, the molecular mechanism of gold biomineralization in microorganisms of industrial relevance remains largely unexplored. Here we describe the biosynthesis mechanism of gold nanoparticles (AuNPs) in the fungus Rhizopus oryzae . Reduction of AuCl(4)(-) [Au(III)] to nanoparticulate Au(0) (AuNPs) occurs in both the cell wall and cytoplasmic region of R. oryzae . The average size of the as-synthesized AuNPs is ~15 nm. The biomineralization occurs through adsorption, initial reduction to Au(I), followed by complexation [Au(I) complexes], and final reduction to Au(0). Subtoxic concentrations (up to 130 ?M) of AuCl(4)(-) in the growth medium increase growth of R. oryzae and induce two stress response proteins while simultaneously down-regulating two other proteins. The induction increases mycelial growth, protein yield, and AuNP biosynthesis. At higher Au(III) concentrations (>130 ?M), both mycelial and protein yield decrease and damages to the cellular ultrastructure are observed, likely due to the toxic effect of Au(III). Protein profile analysis also confirms the gold toxicity on R. oryzae at high concentrations. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis shows that two proteins of 45 and 42 kDa participate in gold reduction, while an 80 kDa protein serves as a capping agent in AuNP biosynthesis. PMID:22708541

Das, Sujoy K; Liang, Jinni; Schmidt, Michael; Laffir, Fathima; Marsili, Enrico

2012-07-24

222

Sensory acceptability evaluation of irradiated rice, oryza sativa indica.  

National Technical Information Service (NTIS)

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

S. Loaharanu M. Sutantawong A. Ungsunanatawiwat

1971-01-01

223

In-depth Analysis of the Magnaporthe oryzae Conidial Proteome  

PubMed Central

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

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

2013-01-01

224

Growth and ?-amylase production by Aspergillus oryzae during continuous cultivations  

Microsoft Academic Search

Continuous cultivations of an ?-amylase producing strain of Aspergillus oryzae were carried out using a chemically defined medium with glucose as the growth limiting component. For steady-state cultures the recovery of carbon was about 99%, indicating that all major carbon components i.e. biomass, carbon dioxide and ?-amylase were measured. The rates of sugar consumption, oxygen consumption and carbon dioxide production

Morten Carlsen; Jens Nielsen; John Villadsen

1996-01-01

225

In-depth analysis of the Magnaporthe oryzae conidial proteome.  

PubMed

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

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

2012-12-01

226

Light represses conidiation in koji mold Aspergillus oryzae.  

PubMed

In the filamentous fungus Aspergillus oryzae, there has been no report on photoreaction. Here we investigated the effect of light in A. oryzae and found that conidiation was repressed by white light. This reaction is contrary to that of other Aspergilli, which show abundant conidiation under light. Moreover, red light also caused reduced conidiation. Genome sequencing of A. oryzae indicated the existence of homologs of some light-related genes in other filamentous fungi. To approach the molecular mechanism of this photoresponse, the effect of red light on the expression level of several genes putatively responsible for conidiation or photoperception, i.e., brlA, a gene known to be required for conidiation, AofphA, the putative homolog of the A. nidulans phytochrome gene fphA, and AoveA, the putative homolog of the negative regulator gene in conidiation in A. nidulans, was examined. These three genes showed no significant response to red light at the transcriptional level. The results indicate that A. oryzae perceives and responds to red light in a manner independent of the transcriptional regulation of these genes. PMID:17690479

Hatakeyama, Riko; Nakahama, Tomoyuki; Higuchi, Yujiro; Kitamoto, Katsuhiko

2007-08-01

227

Increased Activity of a Cationic Peroxidase Associated with an Incompatible Interaction Between Xanthomonas oryzae pv oryzae and Rice (Oryza sativa) 1  

PubMed Central

Rice (Oryza sativa L.) cultivar Cas 209 carries the gene Xa-10 for resistance to race 2 of Xanthomonas oryzae pv oryzae, the bacterial blight pathogen. When seedling leaves of Cas 209 plants were infiltrated with bacterial cell suspensions of strain PXO86Rif (race 2, incompatible), total peroxidase activity in extracts from extracellular spaces increased almost threefold between 16 and 24 hours after inoculation. The increase in total peroxidase activity in extracellular extracts was correlated with the appearance of a 43-kilodalton peroxidase isoenzyme with an isoelectric point of 8.6. Increases in the activities of two anionic peroxidase isoenzymes also were associated with the incompatible interaction. Later during the interactions, total peroxidase activities increased in both compatible (cv Cas 209 infiltrated with race 1, PXO61Sm) and control (Cas 209 infiltrated with water) treatments, but final activity levels were less than that observed in the incompatible combination. Similarly, the cationic peroxidase was detected in all three treatments by 48 hours after infiltration, but at reduced levels in compatible and water-infiltrated control treatments relative to the incompatible combination. Accumulation of this peroxidase in extracellular spaces thus may play a role in the defense response in cultivar Cas 209. ImagesFigure 2Figure 3Figure 4Figure 5

Reimers, Peter J.; Guo, Ailan; Leach, Jan E.

1992-01-01

228

Spermine oxidase: ten years after.  

PubMed

Spermine oxidase (SMO) was discovered much more recently than other enzymes involved in polyamine metabolism; this review summarizes 10 years of researches on this enzyme. Spermine oxidase (SMO) is a FAD-dependent enzyme that specifically oxidizes spermine (Spm) and plays a dominant role in the highly regulated mammalian polyamines catabolism. SMO participates in drug response, apoptosis, response to stressful stimuli and etiology of several pathological conditions, including cancer. SMO is a highly inducible enzyme, its deregulation can alter polyamine homeostasis, and dysregulation of polyamine catabolism is often associated with several disease states. The oxidative products of SMO activity are spermidine, and the reactive oxygen species H(2)O(2) and the aldehyde 3-aminopropanal each with the potential to produce cellular damages and pathologies. The SMO substrate Spm is a tetramine that plays mandatory roles in several cell functions, such as DNA synthesis, cellular proliferation, modulation of ion channels function, cellular signaling, nitric oxide synthesis and inhibition of immune responses. The goal of this review is to cover the main biochemical, cellular and physiological processes in which SMO is involved. PMID:21809080

Cervelli, Manuela; Amendola, Roberto; Polticelli, Fabio; Mariottini, Paolo

2012-02-01

229

Immunological comparison of sulfite oxidase  

SciTech Connect

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

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

1991-03-11

230

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

231

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

PubMed

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

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

2013-09-01

232

Dynamics of Xanthomonas oryzae pv. oryzae Populations in Korea and Their Relationship to Known Bacterial Blight Resistance Genes.  

PubMed

ABSTRACT Developing resistant cultivars requires an understanding of the dynamics of the pathogen populations as well as the genetics of host resistance. Bacterial leaf blight (BB), caused by the vascular pathogen Xanthomonas oryzae pv. oryzae, has become one of the most devastating diseases of rice. We demonstrate here the quantitative analyses of responses of near-isogenic lines carrying various BB resistance (R) genes and R-gene combinations against 16 X. oryzae pv. oryzae isolates representing Korean BB pathotypes. The estimated main effects of each R gene against the 16 isolates identified prominent differences in BB pathotypes between Korea and other countries. Three major aspects of our quantitative observations and statistical analysis are (i) strong and broad resistance of xa5; (ii) independent and additive genetic actions of Xa4, xa5, and Xa21 under digenic or trigenic status; and (iii) a strong quantitative complementation effect contributed by the functional alleles of Xa4 and Xa21. We conclude that the pyramid line containing genes Xa4, xa5, and Xa21 would be the most promising and valuable genotype for improving Korean japonica cultivars for BB resistance. PMID:18943752

Jeung, J U; Heu, S G; Shin, M S; Vera Cruz, C M; Jena, K K

2006-08-01

233

Crystallization and preliminary crystallographic studies of LipA, a secretory lipase/esterase from Xanthomonas oryzae pv. oryzae.  

PubMed

Xanthomonas oryzae pv. oryzae is the causal agent of bacterial leaf blight, a serious disease of rice. Several enzymes that are secreted through the type II secretion system of this bacterium play an important role in the plant-microbe interaction, being important for virulence and also being able to induce potent host defence responses. One of these enzymes is a secretory lipase/esterase, LipA, which shows a very weak homology to other bacterial lipases and gives a positive tributyrin plate assay. In this study, LipA was purified from the culture supernatant of an overexpressing clone of X. oryzae pv. oryzae and two types of crystals belonging to space group C2 but with two different unit-cell parameters were obtained using the hanging-drop vapour-diffusion method. Type I crystals diffract to a maximum resolution of 1.89 A and have unit-cell parameters a = 93.1, b = 62.3, c = 66.1 A, beta = 90.8 degrees . Type II crystals have unit-cell parameters a = 103.6, b = 54.6, c = 66.3 A, beta = 92.6 degrees and diffract to 1.86 A. Solvent-content analysis shows one monomer in the asymmetric unit in both the crystal forms. PMID:17671374

Aparna, Gudlur; Chatterjee, Avradip; Jha, Gopaljee; Sonti, Ramesh V; Sankaranarayanan, Rajan

2007-08-01

234

Zinc uptake regulator (zur) gene involved in zinc homeostasis and virulence of Xanthomonas oryzae pv. oryzae in rice.  

PubMed

Xanthomonas oryzae pv. oryzae causes bacterial leaf blight, one of the most widespread and destructive bacterial diseases in rice. In order to understand the gene of zinc uptake regulator (zur) involved in virulence of the pathogen in rice, we generated a mutant OSZRM by homologous suicide plasmid integration. The mutant failed to grow in NYGB medium supplemented with Zn(2+) or Fe(3+) at a concentration of 500 muM or 6 mM, whereas the wild-type strain grew well at the same conditions. The zur mutant was hypersensitive to hydrogen peroxide and exhibited reduction catalase activity and the production of extracellular polysaccharide (EPS). Interestingly, the mutant showed a reduction in virulence on rice but still kept triggering hypersensitive response (HR) in tobacco. When the mutant was complemented with the zur gene, the response was recovered to wild-type. These results suggested that zur gene is a functional member of the Zur regulator family that controls zinc and iron homeostasis, oxidative stress, and EPS production, which is necessary for virulence in X. oryzae pv. oryzae. PMID:17375359

Yang, Wanfeng; Liu, Yan; Chen, Lei; Gao, Tongchun; Hu, Baishi; Zhang, Dongfang; Liu, Fengquan

2007-04-01

235

Antimicrobial activity and induction of systemic resistance in rice by leaf extract of Datura metel against Rhizoctonia solani and Xanthomonas oryzae pv. oryzae  

Microsoft Academic Search

The leaf extracts of Datura metel significantly reduced the in vitro growth of Rhizoctonia solani (RS7, Anastomosis group AG1) and Xanthomonas oryzae pv. oryzae (Xoo). Methanol extract exhibited the best control of the pathogens recording 10–35% more toxicity than aqueous extract. Foliar application of leaf extracts effectively reduced the incidence of sheath blight and bacterial blight diseases of rice under

Sateesh Kagale; T. Marimuthu; B. Thayumanavan; R. Nandakumar; R. Samiyappan

2004-01-01

236

The Bordetella Bfe System: Growth and Transcriptional Response to Siderophores, Catechols, and Neuroendocrine Catecholamines  

PubMed Central

Ferric enterobactin utilization by Bordetella bronchiseptica and Bordetella pertussis requires the BfeA outer membrane receptor. Under iron-depleted growth conditions, transcription of bfeA is activated by the BfeR regulator by a mechanism requiring the siderophore enterobactin. In this study, enterobactin-inducible bfeA transcription was shown to be TonB independent. To determine whether other siderophores or nonsiderophore catechols could be utilized by the Bfe system, various compounds were tested for the abilities to promote the growth of iron-starved B. bronchiseptica and induce bfeA transcription. The BfeA receptor transported ferric salmochelin, corynebactin, and the synthetic siderophores TRENCAM and MECAM. Salmochelin and MECAM induced bfeA transcription in iron-starved Bordetella cells, but induction by corynebactin and TRENCAM was minimal. The neuroendocrine catecholamines epinephrine, norepinephrine, and dopamine exhibited a remarkable capacity to induce transcription of bfeA. Norepinephrine treatment of B. bronchiseptica resulted in BfeR-dependent bfeA transcription, elevated BfeA receptor production, and growth stimulation. Pyrocatechol, carbidopa, and isoproterenol were similarly strong inducers of bfeA transcription, whereas tyramine and 3,4-dihydroxymandelic acid demonstrated low inducing activity. The results indicate that the inducer structure requires a catechol group for function and that the ability to induce bfeA transcription does not necessarily correlate with the ability to stimulate bacterial growth. The expanded range of catechol siderophores transported by the BfeA receptor demonstrates the potential versatility of the Bordetella Bfe iron retrieval system. The finding that catecholamine neurotransmitters activate bfeA transcription and promote growth suggests that Bordetella cells can perceive and may benefit from neuroendocrine catecholamines on the respiratory epithelium.

Anderson, Mark T.; Armstrong, Sandra K.

2006-01-01

237

Catechol Redox Induced Formation of Metal Core-Polymer Shell Nanoparticles  

PubMed Central

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

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

2011-01-01

238

Eight-coordinate stereochemistries of U(IV) catecholate and aquo complexes  

SciTech Connect

An extended MM3 model has been used to identify all low energy configurations for U(IV) complexes with catecholate and aquo ligands. Both stochastic and systematic conformational analyses of[U(cat)n(OH2)8-n]4-2n complexes, n= 1 - 4, establish that 20 of the 67 possible stereochemistries are minima on the MM3 potential surface. The stable stereochemistries are reported for each stoichiometry and, where possible, the results are compared with experimental data and with the predictions from prior repulsion energy calculations.

Hay, Benjamin P.; Uddin, Jamal; Firman, Timothy K.

2004-01-01

239

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

PubMed

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

Vrchlabský, M; Sommer, L

1968-09-01

240

Crosstalk between mitochondria and NADPH oxidases  

PubMed Central

Reactive oxygen species (ROS) play an important role in physiological and pathological processes. In recent years, a feed-forward regulation of the ROS sources has been reported. The interaction between main cellular sources of ROS, such as mitochondria and NADPH oxidases, however, remain obscure. This work summarizes the latest findings on the role of crosstalk between mitochondria and NADPH oxidases in pathophysiological processes. Mitochondria have the highest levels of antioxidants in the cell and play an important role in the maintenance of cellular redox status, thereby acting as an ROS and redox sink and limiting NADPH oxidase activity. Mitochondria, however, are not only a target for ROS produced by NADPH oxidase but also a significant source of ROS, which under certain condition may stimulate NADPH oxidases. This crosstalk between mitochondria and NADPH oxidases, therefore, may represent a feed-forward vicious cycle of ROS production which can be pharmacologically targeted under conditions of oxidative stress. It has been demonstrated that mitochondria-targeted antioxidants break this vicious cycle, inhibiting ROS production by mitochondria and reducing NADPH oxidase activity. This may provide a novel strategy for treatment of many pathological conditions including aging, atherosclerosis, diabetes, hypertension and degenerative neurological disorders in which mitochondrial oxidative stress seems to play a role. It is conceivable that the use of mitochondria-targeted treatments would be effective in these conditions.

Dikalov, Sergey

2011-01-01

241

Riboflavin kinase couples TNF receptor 1 to NADPH oxidase  

Microsoft Academic Search

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

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

2009-01-01

242

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

Microsoft Academic Search

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

Paul J Harrison; Elizabeth M Tunbridge

2008-01-01

243

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

PubMed Central

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

Zhou, Ming-guo

2013-01-01

244

Electrochemical sensor for catechol and dopamine based on a catalytic molecularly imprinted polymer-conducting polymer hybrid recognition element.  

PubMed

One of the difficulties with using molecularly imprinted polymers (MIPs) and other electrically insulating materials as the recognition element in electrochemical sensors is the lack of a direct path for the conduction of electrons from the active sites to the electrode. We have sought to address this problem through the preparation and characterization of novel hybrid materials combining a catalytic MIP, capable of oxidizing the template, catechol, with an electrically conducting polymer. In this way a network of "molecular wires" assists in the conduction of electrons from the active sites within the MIP to the electrode surface. This was made possible by the design of a new monomer that combines orthogonal polymerizable functionality; comprising an aniline group and a methacrylamide. Conducting films were prepared on the surface of electrodes (Au on glass) by electropolymerization of the aniline moiety. A layer of MIP was photochemically grafted over the polyaniline, via N,N'-diethyldithiocarbamic acid benzyl ester (iniferter) activation of the methacrylamide groups. Detection of catechol by the hybrid-MIP sensor was found to be specific, and catechol oxidation was detected by cyclic voltammetry at the optimized operating conditions: potential range -0.6 V to +0.8 V (vs Ag/AgCl), scan rate 50 mV/s, PBS pH 7.4. The calibration curve for catechol was found to be linear to 144 microM, with a limit of detection of 228 nM. Catechol and dopamine were detected by the sensor, whereas analogues and potentially interfering compounds, including phenol, resorcinol, hydroquinone, serotonin, and ascorbic acid, had minimal effect (< or = 3%) on the detection of either analyte. Non-imprinted hybrid electrodes and bare gold electrodes failed to give any response to catechol at concentrations below 0.5 mM. Finally, the catalytic properties of the sensor were characterized by chronoamperometry and were found to be consistent with Michaelis-Menten kinetics. PMID:19354259

Lakshmi, Dhana; Bossi, Alessandra; Whitcombe, Michael J; Chianella, Iva; Fowler, Steven A; Subrahmanyam, Sreenath; Piletska, Elena V; Piletsky, Sergey A

2009-05-01

245

Isolation of cytoplasmic NADPH-dependent phenol hydroxylase and catechol-1,2-dioxygenase from Candida tropicalis yeast  

PubMed Central

The efficiencies of NADPH-dependent phenol hydroxylase (EC 1.14.13.7) and catechol 1,2-dioxygenase (EC.1.13.11.1) in biodegradation of phenol in the cytosolic fraction isolated from yeast Candida tropicalis were investigated. Enzymatic activities of both NADPH-dependent phenol hydroxylase and catechol 1,2-dioxygenase were detected in the cytosolic fraction of C. tropicalis grown on medium containing phenol. Using the procedure consisting of chromatography on DEAE-Sepharose, fractionation by polyethylene glycol 6000 and gel permeation chromatography on Sepharose 4B the enzyme responsible for phenol hydroxylation in cytosol, NADPH-dependent phenol hydroxylase, was isolated from the cytosolic fraction of C. tropicalis close to homogeneity. However, fractionation with polyethylene glycol 6000 lead to a decrease in catechol 1,2-dioxygenase activity. Therefore, another procedure was tested to purify this enzyme. Gel permeation chromatography of proteins of the eluate obtained by chromatography on a DEAE-Sepharose column was utilized to separate phenol hydroxylase and catechol 1,2-dioxygenase. Among gel permeation chromatography on columns of Sephadex G-100, Sephacryl S-300 and Sepharose 4B tested for their efficiencies to isolate phenol hydroxylase and catechol 1,2-dioxygenase, that on Sephacryl S-300 was found to be suitable for such a procedure. Nevertheless, even this chromatographic method did not lead to obtain catechol 1,2-dioxygenase in sufficient amounts and purity for its further characterization. The data demonstrate the progress in resolving the enzymes responsible for the first two steps of phenol degradation by the C. tropicalis strain.

Vilimkova, Lenka; Paca, Jan; Kremlackova, Veronika; Paca, Jan; Stiborova, Marie

2008-01-01

246

Monoamine oxidase inhibitors and neuroprotection: a review.  

PubMed

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

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

2012-11-01

247

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

Microsoft Academic Search

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

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

2011-01-01

248

Cleavage of the Nb=O bond of oxoniobium(V) porphyrins. Synthesis and characterization of novel niobium(V) porphyrins with two distinct catechols  

SciTech Connect

A novel catecholato complex, Nb{sup v}(tpp)(cat)(Hcat), where cat and Hcat are two distinct catechol ligands (a bidentate catecholate dianion and a monodentate catecholate monoanion, respectively) and tpp is 5, 10, 15, 20-tetaphenylporphyrin dianion, has been isolated in the reaction of Nb{sup v} (tpp)(O)(AcO) with catechol, where AcO is an acetatoligand. Its molecular structure has been determined by X-ray crystallography. Crystal data: monoclinic, space group P2{sub 1}/c, Z = 4, a = 14.592(3) {Angstrom}, b = 23.46(1) {Angstrom}, c = 14.415(4) {Angstrom}, {beta} = 100.95(2){degrees}, R = 0.079. The heptacoordinate niobium atom is displaced by 1.02 {Angstrom} from the mean plane of the four nitrogen atoms. The structure of the complex in solution and the mechanism of the Nb=O cleavage were investigated by means of {sup 1}H-NMR spectroscopy. The bidentate catechol is oriented in C{sub s} symmetry with respect to the porphyrin plane, and the monodentate catechol is located perpendicularly to both the bidentate catechol and the porphyrin plane. Two intermediates with the bidentate catechol were observed after addition of 2 equiv of catechol to Nb(tmp)(O)(AcO) at -30 {degrees}C, where tmp denotes the 5,10,15,20-tetramesitylporphyrin dianion. These intermediates were determined to be Nb(tmp)(cat)(OH) and Nb(tmp)(cat)(AcO). Thus, the Nb=O bond of Nb(tmp)(O)(AcO) was easily cleaved to create the two intermediates. The authors propose a unique route to the Nb=O cleavage that involves an intramolecular electron transfer from the catechol ligand coordinated at the first stage through a ligand exchange with AcO. Both protonation and electron transfer to the Nb=O moiety play important roles in the Nb=O cleavage.

Kurihara, Masato; Kotoh, Noriyuki; Kojima, Takahiko [Kyushu Univ., Fukuoka (Japan)] [and others

1995-09-13

249

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

PubMed

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

Chang, Perng-Kuang; Ehrlich, Kenneth C

2010-04-15

250

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

251

Genetic polymorphisms in the catechol estrogen metabolism pathway and breast cancer risk  

PubMed Central

Background This study investigated whether single nucleotide polymorphisms (SNPs) in genes within the catechol estrogen metabolism pathway altered the risk of breast cancer alone or in combination, as well as whether menopausal hormone therapy (HT) modified the effect of these SNPs on breast cancer risk. Methods In a population-based case-control study of breast cancer, 891 cases and 878 controls were genotyped for six functional SNPs in the COMT, CYP1B1, GSTM1, GSTP1, and GSTT1 genes. Results Women homozygous with the T allele in CYP1B1*2 (Ser119; rs1056827) were at 1.69 (95% confidence interval [CI]: 1.17–2.46) times the risk of women homozygous with the G allele; women homozygous with the G allele in GSTP1 (Val105; rs1695) were at 0.73 (95% CI: 0.54–0.99) times the risk of breast cancer compared to women homozygous with the A allele. No other SNPs tested were associated with breast cancer to any appreciable degree. Potential gene-gene and gene-HT interactions were investigated. Conclusion With the exception of GSTP1 and possibly CYP1B1*2, our findings do not provide support for the role of genetic variation in the catechol estrogen metabolism pathway and breast cancer risk in post-menopausal women.

Reding, Kerryn W.; Weiss, Noel S.; Chen, Chu; Li, Christopher I.; Carlson, Christopher S.; Wilkerson, Hui-Wen; Farin, Federico M.; Thummel, Kenneth E.; Daling, Janet R.; Malone, Kathleen E.

2009-01-01

252

Inhibitors of catechol-O-methyltransferase in the treatment of neurological disorders.  

PubMed

Catechol-O-methyltransferase (COMT) is the enzyme which catalyzes the transfer of a methyl group from S-adenosylmethionine to catechols and catecholamines, like the neurotransmitters dopamine, epinephrine and norepinephrine. COMT has implications in many neurological and psychiatric disorders like schizophrenia, Parkinson's disease (PD), bipolar disorders, etc. and therefore, it serves as an important drug target. Since its characterization in 1957, many inhibitors were designed where the first generation inhibitors were found to be highly toxic, short acting and had poor bioavailability. Currently, two of the second generation inhibitors, tolcapone and entacapone have been used for treatment of PD but are associated with various dopaminergic and gastro-intestinal side-effects. There have been several approaches for the design of novel COMT inhibitors with a good and safe therapeutic profile. The focus of this article is to review the current knowledge on COMT and the role of COMT inhibitors in the treatment of neurological disorders. The inhibitors have been classified into six different classes based on the structural framework. A historical overview of the discovery and development of COMT inhibitors is presented with a special emphasis on new generation of inhibitors till date. PMID:24450388

Jatana, Nidhi; Apoorva, N; Malik, Sonika; Sharma, Aditya; Latha, Narayanan

2013-01-01

253

Ormosil gels doped with engineered catechol 1,2 dioxygenases for chlorocatechol bioremediation.  

PubMed

Enzymes entrapped in wet, nanoporous silica gel have great potential as bioreactors for bioremediation because of their improved thermal, chemical, and mechanical stability with respect to enzymes in solution. The B isozyme of catechol 1,2 dioxygenase from Acinetobacter radioresistens and its mutants of Leu69 and Ala72, designed for an increased reactivity toward the environmental pollutant chlorocatechols, were encapsulated using alkoxysilanes and alkyl alkoxysilanes as precursors in varying proportions. Encapsulation of the mutants in a hydrophobic tetramethoxysilane/dimethoxydimethylsilane-based matrix yielded a remarkable 10- to 12-fold enhancement in reactivity toward chlorocatechols. These gels also showed a fivefold increase in relative reactivity toward chlorocatechols with respect to the natural substrate catechol, thus compensating for their relatively low activity for these substrates in solution. The encapsulated enzyme, unlike the enzyme in solution, proved resilient in assays carried out in urban wastewater and bacteria-contaminated solutions mimicking environmentally relevant conditions. Overall, the combination of a structure-based rational design of enzyme mutants, and the selection of a suitable encapsulation material, proved to be a powerful approach for the production and optimization of a potential bioremediation device, with increased activity and resistance toward bacterial degradation. PMID:24571591

Micalella, Chiara; Caglio, Raffaella; Mozzarelli, Andrea; Valetti, Francesca; Pessione, Enrica; Giunta, Carlo; Bruno, Stefano

2014-05-01

254

Heterobimetallic catechol-phosphine complexes with palladium and a group-13 element: structural flexibility and dynamics.  

PubMed

Group-13 metal acetylacetonates [M(acac)3] (M = Al, Ga, In) or Al(OiPr)3 react with a complex [Pd(catphosH)2] that may act as chelating ligand towards a second metal, or with a mixture of catechol phosphine (catphosH2) and [PdCl2(cod)], to give heterometallic complexes featuring either dinuclear M(catphos)2Pd or trinuclear M{(catphos)2Pd}2 motifs. Characterisation of the products by crystallographic and solution NMR studies gives insight into the structural diversity and flexibility of the coordination environments of the group-13 elements and their impact on the stability of the multinuclear complexes. The results indicate that gallium and indium are the most suitable elements for the stabilisation of di- and trinuclear assemblies, respectively. Dynamic NMR spectroscopy allowed to follow the dynamic averaging of the coordination environments of the four distinguishable catechol phosphines in the indium complex [M{(catphos)2Pd}2]H. The results revealed that the isomerisation follows a complicated pathway involving several distinguishable proton transfer steps, and allowed to propose a mechanistic explanation for the observed isomerisation. PMID:24802543

Bauer, G; Nieger, M; Gudat, D

2014-06-21

255

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

PubMed Central

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

de Jesus Rivas, Nilo; Whitaker, John R.

1973-01-01

256

Characterization of a neutral ceramidase orthologue from Aspergillus oryzae.  

PubMed

Ceramide is an important molecule not only structurally but also regulationally as a modulator of various cellular events. Ceramidase (CDase) are classified into three different types (acid, alkaline, and neutral CDases). Neutral CDase could play an important role in the regulation of ceramide levels in the extracellular space. In this study, we describe the characterization of a neutral CDase orthologue from the filamentous fungus Aspergillus oryzae. The gene encoding the neutral CDase orthologue was cloned and overexpressed in A. oryzae. The purified recombinant enzyme was optimally active at pH 4.0-4.5 and 40 degrees C. The apparent K(m) and V(max) values of the enzyme for C12-NBD-ceramide were 3.32 microM and 0.085 micromol min(-1) mg(-1), respectively. PMID:19650849

Tada, Sawaki; Matsushita-Morita, Mayumi; Suzuki, Satoshi; Kusumoto, Ken-Ichi; Kashiwagi, Yutaka

2009-09-01

257

Activation of Polyphenol Oxidase of Chloroplasts 1  

PubMed Central

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

Tolbert, N. E.

1973-01-01

258

Genes for enhancing resistance to Magnaporthe oryzae and uses thereof  

US Patent & Trademark Office Database

The present invention relates to Pi5-1 and Pi5-2 proteins which enhance resistance to Mag-naporthe oryzae, genes which encode the proteins, a recombinant vector comprising the genes, a plant transformed with the recombinant vector and seeds thereof, a method of increasing resistance to a plant pathogen by expressing the genes in a plant, antibodies against the proteins, and a composition comprising the genes which are useful for enhancing resistance to a plant pathogen.

2013-03-05

259

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

260

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

Microsoft Academic Search

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

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

1998-01-01

261

Extracellular acid protease from Rhizopus oryzae: purification and characterization  

Microsoft Academic Search

Extracellular aspartate protease from Rhizopus oryzae was purified 91 times with 26% recovery using (NH4)2SO4 fractionation, ion-exchange and size-exclusion chromatographic techniques. The enzyme was found to be monomeric in nature having a molecular mass of 34kDa. The enzyme acts optimally at 60°C with activation energy of 15.16kcal\\/mol and was stable in the temperature range of 30–45°C. The purified enzyme is

Sushil Kumar; Neeru S. Sharma; Mukh R. Saharan; Randhir Singh

2005-01-01

262

Production of gallic acid by immobilization of Rhizopus oryzae  

Microsoft Academic Search

Production of gallic acid using the immobilized cells of Rhizopus oryzae has been studied. It was observed that 2% tannic acid concentration, 200 numbers of calcium alginate beads of spore concentration 2 2 105\\/ml and initial pH 5.0 gave the maximum gallic acid production. The % of tannin conversion was 78.5% whereas in free cell culture, the % conversion was

S. K. Misro; M. R. Kumar; R. Banerjee; B. C. Bhattacharyya

1997-01-01

263

Purification, characterization and immobilization of a keratinase from Aspergillus oryzae  

Microsoft Academic Search

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

Aida M Farag; Maha A Hassan

2004-01-01

264

The mouse liver aldehyde oxidase locus ( Aox )  

Microsoft Academic Search

Wide variability has been demonstrated in the properties and presumably the genetic constitution of aldehyde oxidases of 30 different strains of inbred mice. Genetic control of aldehyde oxidase (Aox) has been shown to reside in linkage group XIII and to be 9.6±0.4 recombination units from isocitric dehydrogenase (Id-1) and 28.3±3.5 recombination units from dipeptidase-1 (Dip-1). On the basis of these

J. G. Watson; T. J. Higgins; P. B. Collins; S. Chaykin

1972-01-01

265

Lysyl Oxidase, Cellular Senescence and Tumor Suppression  

Microsoft Academic Search

Replicative senescence may provide a mechanism of tumor suppression and tumor suppressor genes of the extracellular matrix, like lysyl oxidase, may play a role in cellular senescence. To test this hypothesis and determine whether the extracellular matrix may serve as a marker, the steady-state levels of human lysyl oxidase, a-I type III collagen and ß-actin transcripts were assessed in various

Rashmi Sharma; Jeffrey A. Kramer; Stephen A. Krawetz

1997-01-01

266

Tumor suppressive effect of lysyl oxidase proenzyme  

Microsoft Academic Search

Lysyl oxidase acts as both a matrix modifying enzyme and an oncogene suppressor. It is synthesized as a 50-kDa proenzyme, secreted, and processed into an ?30 kDa mature, active enzyme and an 18-kDa propeptide. The tumor suppressive effect of lysyl oxidase appears to be exerted within the cell, so the subcellular localization of protein forms was investigated. Propeptide-specific antibody detected 50-kDa

Sara Contente; Tze-Jou Annie Yeh; Robert M. Friedman

2009-01-01

267

Structure of the human lysyl oxidase gene  

Microsoft Academic Search

Lysyl oxidase (EC 1.4.3.13), an extracellular copper enzyme, initiates the crosslinking of collagens and elastin by catalyzing oxidative deamination of the [epsilon]-amino group in certain lysine and hydroxylysine residues. The authors report here that the human lysyl oxidase gene is about 15 kb in size and consists of seven exons. Transcription is initiated at one major site and four minor

E. R. Haemaelaeinen; R. Kemppainen; T. Pihlajaniemi; K. I. Kivirikko

1993-01-01

268

Mimicking the intradiol catechol cleavage activity of catechol dioxygenase by high-spin iron(III) complexes of a new class of a facially bound [N2O] ligand.  

PubMed

A series of high-spin iron(III) complexes, {N-R-2-[(pyridin-2-ylmethyl)amino]acetamide}FeCl(3) [R = mesityl (1b), 2,6-Et(2)C(6)H(3) (2b), and 2,6-i-Pr(2)C(6)H(3) (3b)], that functionally emulate the intradiol catechol dioxygenase enzyme are reported. In particular, these enzyme mimics, 1b, 2b, and 3b, which utilized molecular oxygen in carrying out the intradiol catechol cleavage of 3,5-di-tert-butylcatechol with high regioselectivity (ca. 81-85%) at room temperature under ambient conditions, were designed by employing a new class of a facially bound [N(2)O] ligand, namely, N-R-2-[(pyridin-2-ylmethyl)amino]acetamide [R = mesityl (1a), 2,6-Et(2)C(6)H(3) (2a), and 2,6-i-Pr(2)C(6)H(3) (3a)]. The density functional theory studies revealed that the intradiol catechol cleavage reaction proceeded by an iron(III) peroxo intermediate that underwent 1,2-Criegee rearrangement to yield the intradiol catechol cleaved products analogous to the native enzyme. PMID:19006298

Panda, Manas K; John, Alex; Shaikh, Mobin M; Ghosh, Prasenjit

2008-12-15

269

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

270

The mammalian aldehyde oxidase gene family  

PubMed Central

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

2009-01-01

271

PPAR? and Proline Oxidase in Cancer  

PubMed Central

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

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

2008-01-01

272

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 108kDa and GLP was identified as a pentamer containing five subunits of 22kDa. The optimum pH and temperature for PPO catalyzing activity of GLP was 6.5 and 65°C, respectively. Kinetic constants were 0.0365M and 0.0196M 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

273

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

274

Construction and characterization of a copy number-inducible fosmid library of Xanthomonas oryzae pathovar oryzae MAFF311018.  

PubMed

A fosmid library of Xanthomonas oryzae pathovar oryzae MAFF311018 (T7174), the causative agent of bacterial blight on rice, was constructed and characterized. The average fosmid library insert size was >34kb, and 967 clones were uniquely positioned on its sequenced genome. The entire Xoo MAFF311018 genome was covered by end-sequenced clones with at least 5kb of overlap. The fosmid vector contains both the single-copy Escherichia coli fertility factor origin, which enhances fosmid stability, and the multi-copy IncP? origin, allowing amplification of copy number upon induction with l-arabinose. Real-time quantitative PCR on 12 randomly picked fosmid library clones determined that fosmid copy number increased 8- to 58-fold after 5hour induction. This library provides a new resource for complementation experiments and systematic functional studies in Xoo and related species. PMID:24835513

Ichida, Hiroyuki; Sun, Xiaoying; Imanaga, Suguru; Ito, Yasuhiro; Yoneyama, Katsuyoshi; Kuwata, Shigeru; Ohsato, Shuichi

2014-08-01

275

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

PubMed

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

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

2014-05-01

276

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

PubMed

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

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

2008-11-01

277

Recombinant expression and purification of functional XorII, a restriction endonuclease from Xanthomonas oryzae pv. oryzae.  

PubMed

An endonuclease from Xanthomonas oryzae pathovar oryzae KACC 10331, XorII, was recombinantly produced in Escherichia coli using a T7 system. XorII was purified using a combination of ion exchange and immobilized metal affinity chromatography (IMAC). An optimized washing protocol was carried out on an IMAC in order to obtain a high purity product. The final amount of purified XorII was approximately 2.5 mg/L of LB medium. The purified recombinant XorII was functional and showed the same cleavage pattern as PvuI. The enzyme activity tested the highest at 25 degrees in 50 mM NaCl, 10 mM Tris-HCl, 10 mM MgCl2, and 1 mM dithiothreitol at a pH of 7.9. PMID:17483805

Hwang, Dong Kyu; Cho, Jae-Yong; Chae, Young Kee

2007-04-01

278

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...

279

The key role of chlorocatechol 1,2-dioxygenase in phytoremoval and degradation of catechol by transgenic Arabidopsis.  

PubMed

Transgenic exploitation of bacterial degradative genes in plants has been considered a favorable strategy for degrading organic pollutants in the environment. The aromatic ring characteristic of these pollutants is mainly responsible for their recalcitrance to degradation. In this study, a Plesiomonas-derived chlorocatechol 1,2-dioxygenase (TfdC) gene (tfdC), capable of cleaving the aromatic ring, was introduced into Arabidopsis (Arabidopsis thaliana). Morphology and growth of transgenic plants are indistinguishable from those of wild-type plants. In contrast, they show significantly enhanced tolerances to catechol. Transgenic plants also exhibit strikingly higher capabilities of removing catechol from their media and high efficiencies of converting catechol to cis,cis-muconic acid. As far-less-than-calculated amounts of cis,cis-muconic acid were accumulated within the transgenic plants, existence of endogenous TfdD- and TfdE-like activities was postulated and, subsequently, putative orthologs of bacterial tfdD and tfdE were detected in Arabidopsis. However, no TfdC activity and no putative orthologs of either tfdC or tfdF were identified. This work indicates that the TfdC activity, conferred by tfdC in transgenic Arabidopsis, is a key requirement for phytoremoval and degradation of catechol, and also suggests that microbial degradative genes may be transgenically exploited in plants for bioremediation of aromatic pollutants in the environment. PMID:16935988

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

2006-10-01

280

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 10.24nM and 15.00nM (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

281

Proteasome Inhibition in Human Breast Cancer Cells with High Catechol-O-methyltransferase Activity by Green tea polyphenol EGCG analogs  

PubMed Central

A pro-drug 8 of a synthetic analog 7 is more active in its anti-proliferative activity against human breast cancer MDA-MB-231 cells possessing high Catechol-O-methyltransferase (COMT) activity than the pro-drugs of EGCG and the analog 5. The higher activity of 8 is attributed to it not being a substrate of COMT.

Huo, Congde; Yang, Huanjie; Cindy Cui, Qiuzhi; Dou, Q. Ping; Chan, Tak Hang

2010-01-01

282

Variants in the catechol-o-methyltransferase (COMT) gene are associated with schizophrenia in Irish high-density families  

Microsoft Academic Search

The enzyme catechol-o-methyltransferase (COMT) transfers a methyl group from adenosylmethionine to catecholamines including the neurotransmitters dopamine, epinephrine and norepinephrine. This methylation results in the degradation of catecholamines. The involvement of the COMT gene in the metabolic pathway of these neurotransmitters has made it an attractive candidate gene for many psychiatric disorders. In this article, we reported our study of association

X Chen; X Wang; A F O'Neill; D Walsh; K S Kendler

2004-01-01

283

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

284

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

Microsoft Academic Search

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

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

285

Targeting NADPH oxidases in vascular pharmacology  

PubMed Central

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

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

2012-01-01

286

Targeting NADPH oxidases in vascular pharmacology.  

PubMed

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

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

2012-01-01

287

Virulence analysis and gene expression profiling of the pigment-deficient mutant of Xanthomonas oryzae pathovar oryzae.  

PubMed

Xanthomonas oryzae pathovar oryzae (Xoo) causes bacterial blight disease in rice (Oryza sativa L.). For a study of function, we constructed a random insertion mutant library of Xoo using a Tn5 transposon and isolated the mutant strain (M11; aroK::Tn5) that had extremely low pigment production. In addition, M11 had decreased virulence against the susceptible rice cultivar IR24. Thermal asymmetric interlaced-PCR and sequence analysis of M11 revealed that the transposon was inserted into the aroK gene (which encodes a shikimate kinase). To investigate the expression patterns of the pigment- and virulence-deficient mutant, DNA microarray analysis was performed. In addition, reverse transcriptase-PCR was performed to confirm the expression levels of several genes, including the aro genes of the aroK mutant. Our findings reveal that several crucial genes for virulence, including cellulase and hypersensitive response and pathogenicity (hrp) genes, were regulated by mutations in the aroK gene. PMID:20132309

Park, Young-Jin; Song, Eun-Sung; Noh, Tae-Hwan; Kim, Hyungtae; Yang, Kap-Seok; Hahn, Jang-Ho; Kang, Hee-Wan; Lee, Byoung-Moo

2009-12-01

288

Azide inhibition of urate oxidase.  

PubMed

The inhibition of urate oxidase (UOX) by azide was investigated by X-ray diffraction techniques and compared with cyanide inhibition. Two well characterized sites for reagents are present in the enzyme: the dioxygen site and the substrate-binding site. To examine the selectivity of these sites towards azide inhibition, several crystallization conditions were developed. UOX was co-crystallized with azide (N3) in the presence or absence of either uric acid (UA, the natural substrate) or 8-azaxanthine (8AZA, a competitive inhibitor). In a second set of experiments, previously grown orthorhombic crystals of the UOX-UA or UOX-8AZA complexes were soaked in sodium azide solutions. In a third set of experiments, orthorhombic crystals of UOX with the exchangeable ligand 8-nitroxanthine (8NXN) were soaked in a solution containing uric acid and azide simultaneously (competitive soaking). In all assays, the soaking periods were either short (a few hours) or long (one or two months). These different experimental conditions showed that one or other of the sites, or the two sites together, could be inhibited. This also demonstrated that azide not only competes with dioxygen as cyanide does but also competes with the substrate for its enzymatic site. A model in agreement with experimental data would be an azide in equilibrium between two sites, kinetically in favour of the dioxygen site and thermodynamically in favour of the substrate-binding site. PMID:25005084

Gabison, Laure; Colloc'h, Nathalie; Prangé, Thierry

2014-07-01

289

Molecular Basis of Sulfite Oxidase Deficiency from the Structure of Sulfite Oxidase  

Microsoft Academic Search

The molybdenum-containing enzyme sulfite oxidase catalyzes the conversion of sulfite to sulfate, the terminal step in the oxidative degradation of cysteine and methionine. Deficiency of this enzyme in humans usually leads to major neurological abnormalities and early death. The crystal structure of chicken liver sulfite oxidase at 1.9 Ĺ resolution reveals that each monomer of the dimeric enzyme consists of

Caroline Kisker; Hermann Schindelin; Andrew Pacheco; William A Wehbi; Robert M Garrett; K. V Rajagopalan; John H Enemark; D. C Rees

1997-01-01

290

Manipulating dynamics with chemical structure: probing vibrationally-enhanced tunnelling in photoexcited catechol.  

PubMed

Ultrafast time-resolved velocity map ion imaging (TR-VMI) and time-resolved ion-yield (TR-IY) methods are utilised to reveal a comprehensive picture of the electronic state relaxation dynamics in photoexcited catechol (1,2-dihydroxybenzene). After excitation to the S1 ((1)??*) state between 280.5 (the S1 origin band, S1(v = 0)) to 243 nm, the population in this state is observed to decay through coupling onto the S2 ((1)??*) state, which is dissociative with respect to the non-hydrogen bonded 'free' O-H bond (labelled O(1)-H). This process occurs via tunnelling under an S1/S2 conical intersection (CI) on a timeframe of 5-11 ps, resulting in O(1)-H bond fission along S2. Concomitant formation of ground state catechoxyl radicals (C6H5O2(X)), in coincidence with translationally excited H-atoms, occurs over the same timescale as the S1 state population decays. Between 254-237 nm, direct excitation to the S2 state is also observed, manifesting in the ultrafast (~100 fs) formation of H-atoms with high kinetic energy release. From these measurements we determine that the S1/S2 CI lies ~3700-5500 cm(-1) above the S1(v = 0) level, indicating that the barrier height to tunnelling from S1(v = 0) ? S2 is comparable to that observed in the related 'benchmark' species phenol (hydroxybenzene). We discuss how a highly 'vibrationally-enhanced' tunnelling mechanism is responsible for the two orders of magnitude enhancement to the tunnelling rate in catechol, relative to that previously determined in phenol (>1.2 ns), despite similar barrier heights. This phenomenon is a direct consequence of the non-planar S1 excited state minimum structure (C1 symmetry) in catechol, which in turn yields relaxed symmetry constraints for vibronic coupling from S1(v = 0) ? S2- a scenario which does not exist for phenol. These findings offer an elegant example of how even simple chemical modifications (ortho-hydroxy substitution) to a fundamental, biologically relevant, UV chromophore, such as phenol, can have profound effects on the ensuing excited state dynamics. PMID:23549305

Chatterley, Adam S; Young, Jamie D; Townsend, Dave; ?urek, Justyna M; Paterson, Martin J; Roberts, Gareth M; Stavros, Vasilios G

2013-05-14

291

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

292

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

293

Regulation of NADPH Oxidase Activity in Phagocytes  

PubMed Central

The X+-linked chronic granulomatous disease (X+-CGD) variants are natural mutants characterized by defective NADPH oxidase activity but with normal Nox2 expression. According to the three-dimensional model of the cytosolic Nox2 domain, most of the X+-CGD mutations are located in/or close to the FAD/NADPH binding regions. A structure/function study of this domain was conducted in X+-CGD PLB-985 cells exactly mimicking 10 human variants: T341K, C369R, G408E, G408R, P415H, P415L, ?507QKT509-HIWAinsert, C537R, L546P, and E568K. Diaphorase activity is defective in all these mutants. NADPH oxidase assembly is normal for P415H/P415L and T341K mutants where mutation occurs in the consensus sequences of NADPH- and FAD-binding sites, respectively. This is in accordance with their buried position in the three-dimensional model of the cytosolic Nox2 domain. FAD incorporation is abolished only in the T341K mutant explaining its absence of diaphorase activity. This demonstrates that NADPH oxidase assembly can occur without FAD incorporation. In addition, a defect of NADPH binding is a plausible explanation for the diaphorase activity inhibition in the P415H, P415L, and C537R mutants. In contrast, Cys-369, Gly-408, Leu-546, and Glu-568 are essential for NADPH oxidase complex assembly. However, according to their position in the three-dimensional model of the cytosolic domain of Nox2, only Cys-369 could be in direct contact with cytosolic factors during oxidase assembly. In addition, the defect in oxidase assembly observed in the C369R, G408E, G408R, and E568K mutants correlates with the lack of FAD incorporation. Thus, the NADPH oxidase assembly process and FAD incorporation are closely related events essential for the diaphorase activity of Nox2.

Debeurme, Franck; Picciocchi, Antoine; Dagher, Marie-Claire; Grunwald, Didier; Beaumel, Sylvain; Fieschi, Franck; Stasia, Marie-Jose

2010-01-01

294

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

Microsoft Academic Search

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

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

295

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

PubMed

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

Saito, Katsuichi; Hasa, Yasuhiro; Abe, Hideyuki

2012-08-01

296

Molecular basis for enhanced activity of posaconazole against Absidia corymbifera and Rhizopus oryzae.  

PubMed

Posaconazole and itraconazole were more potent inhibitors of ergosterol synthesis, in both intact cells and cell extracts from Absidia corymbifera and Rhizopus oryzae, than voriconazole and fluconazole. Similarly, expression of CYP51 from R. oryzae in Saccharomyces cerevisiae significantly increased resistance to fluconazole and voriconazole but not to posaconazole and itraconazole. PMID:16966400

Chau, Andrew S; Chen, Guodong; McNicholas, Paul M; Mann, Paul A

2006-11-01

297

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

PubMed

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; Tohno, Masanori

2014-01-01

298

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

Microsoft Academic Search

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

Rudravaram Ravinder; Linga Venkateshwar Rao; Pogaku Ravindra

2003-01-01

299

A Study on the Essential Substance for the Growth of Piricularia Oryzae.  

National Technical Information Service (NTIS)

The report discusses a part of an investigation on Piricularia oryzae disease spanning the years 1942 to 1945. The study of P. oryzae involved the cultivation of the fungus - its growth and production were excellent - when there was no basic culture mediu...

E. Hirata

1964-01-01

300

Wild Oryza species as potential sources of drought-adaptive traits  

Microsoft Academic Search

Wild species of Oryza may serve as sources of superior drought tolerance alleles for cultivated rice. In a series of three screenhouse experiments, we compared traits associated with leaf water status, stomatal conductance, membrane stability, and root development in several wild Oryza accessions and O. sativa cultivars, when grown under well-watered or water-deficient conditions. One accession of O. longistaminata had

L. Liu; R. Lafitte; D. Guan

2004-01-01

301

Production of L(+)-lactic acid with Rhizopus oryzae immobilized in polyurethane foam cubes  

Microsoft Academic Search

Polyurethane foam cubes were employed as carriers to immobilize Rhizopus oryzae for L(+)-lactic acid production. The immobilizing capacity reached 450 g-fresh cell\\/l-cube. The production rate of L(+)-lactic acid could be threefold increased by using the immobilized R. oryzae. The immobilized cells could be steadily used in repetitive fermentations for more than 10 batches.

Xiao-Yan Dong; Shu Bai; Yan Sun

1996-01-01

302

A catechol-O-methyltransferase that is essential for auditory function in mice and humans  

PubMed Central

We have identified a previously unannotated catechol-O-methyltranferase (COMT), here designated COMT2, through positional cloning of a chemically induced mutation responsible for a neurobehavioral phenotype. Mice homozygous for a missense mutation in Comt2 show vestibular impairment, profound sensorineuronal deafness, and progressive degeneration of the organ of Corti. Consistent with this phenotype, COMT2 is highly expressed in sensory hair cells of the inner ear. COMT2 enzymatic activity is significantly reduced by the missense mutation, suggesting that a defect in catecholamine catabolism underlies the auditory and vestibular phenotypes. Based on the studies in mice, we have screened DNA from human families and identified a nonsense mutation in the human ortholog of the murine Comt2 gene that causes nonsyndromic deafness. Defects in catecholamine modification by COMT have been previously implicated in the development of schizophrenia. Our studies identify a previously undescribed COMT gene and indicate an unexpected role for catecholamines in the function of auditory and vestibular sense organs.

Du, Xin; Schwander, Martin; Moresco, Eva Marie Y.; Viviani, Pia; Haller, Claudia; Hildebrand, Michael S.; Pak, Kwang; Tarantino, Lisa; Roberts, Amanda; Richardson, Heather; Koob, George; Najmabadi, Hossein; Ryan, Allen F.; Smith, Richard J. H.; Muller, Ulrich; Beutler, Bruce

2008-01-01

303

Nonsynonimous mutation of catechol-O-methyl-transferase (COMT) gene in a patient with temporomandibular disorder.  

PubMed

We report a case of temporomandibular disorder patient with disc displacement without reduction, myofascial pain, limited opening and a novel, never described, nonsynonimous mutation of catechol-O-methyl-transferase (COMT) gene. COMT is one of the enzymes that metabolizes catecholamines, thereby acting as a key modulator of dopaminergic and adrenergic/noradrenergic neurotransmissions, which play a key role in pain modulation. This novel mutation, p.R58S, changed a codon (58 from arginine to serine) in the COMT protein. The introduction of a serine residue in a highly organised secondary structure, in critical regions of the protein, results in a structural alteration. Therefore, we speculate an influence of the mutation on the high pain sensitivity of the patient. PMID:20974455

D'Antň, Vincenzo; Michelotti, Ambrosina; Esposito, Luciana; Zagari, Adriana; Liguori, Rosario; Sacchetti, Lucia

2010-01-01

304

Novel iron(III) complexes with imidazole containing tripodal ligands as model systems for catechol dioxygenases  

Microsoft Academic Search

The iron (III) complexes [Fe(bpia)Cl2][FeCl4] (1), [Fe(bipa)Cl2](ClO4) (2), and [Fe2O(bpia)2Cl2]Cl2(4MeOH (3) (bpia: bis[(2-pyridyl)methyl][(1-methylimidazol-2-yl)methyl]amine, bipa: bis[(1-methylimidazol-2-yl)methyl][(2-pyridyl)methyl]amine) were synthesized. 1 and 2 are structural and functional models for catechol 1,2-dioxygenase. All compounds are characterized by spectroscopic methods and X-ray structure analysis. 3 was also investigated by EXAFS. The coordination environment around all Fe(III) cores is distorted octahedral by the tripodal ligand, chloride,

Matthias Pascaly; Mark Duda; Annette Rompel; Bernd H. Sift; Wolfram Meyer-Klaucke; Bernt Krebs

1999-01-01

305

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

PubMed

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

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

2004-04-30

306

The synthesis, structure and activity evaluation of pyrogallol and catechol derivatives as Helicobacter pylori urease inhibitors.  

PubMed

Some pyrogallol and catechol derivatives were synthesized, and their urease inhibitory activity was evaluated by using acetohydroxamic acid (AHA), a well known Helicobacter pylori urease inhibitor, as positive control. The assay results indicate that many compounds have showed potential inhibitory activity against H. pylori urease. 4-(4-Hydroxyphenethyl)phen-1,2-diol (2a) was found to be the most potent urease inhibitor with IC(50)s of 1.5±0.2 ?M for extracted fraction and 4.2±0.3 ?M for intact cell, at least 10 times and 20 times lower than those of AHA (IC(50) of 17.2±0.9 ?M, 100.6±13 ?M), respectively. This finding indicate that 2a would be a potential urease inhibitor deserves further research. Molecular dockings of 2a into H. pylori urease active site were performed for understanding the good activity observed. PMID:20801557

Xiao, Zhu-Ping; Ma, Tao-Wu; Fu, Wei-Chang; Peng, Xiao-Chun; Zhang, Ai-Hua; Zhu, Hai-Liang

2010-11-01

307

Ultraviolet resonance Raman study of drug binding in dihydrofolate reductase, gyrase, and catechol O-methyltransferase.  

PubMed Central

This paper presents a study of the use of ultraviolet resonance Raman (UVRR) spectroscopic methods as a means of elucidating aspects of drug-protein interactions. Some of the RR vibrational bands of the aromatic amino acids tyrosine and tryptophan are sensitive to the microenvironment, and the use of UV excitation radiation allows selective enhancement of the spectral features of the aromatic amino acids, enabling observation specifically of their change in microenvironment upon drug binding. The three drug-protein systems investigated in this study are dihydrofolate reductase with its inhibitor trimethoprim, gyrase with novobiocin, and catechol O-methyltransferase with dinitrocatechol. It is demonstrated that UVRR spectroscopy has adequate sensitivity to be a useful means of detecting drug-protein interactions in those systems for which the electronic absorption of the aromatic amino acids changes because of hydrogen bonding and/or possible dipole-dipole and dipole-polarizability interactions with the ligand.

Couling, V W; Fischer, P; Klenerman, D; Huber, W

1998-01-01

308

A two-electron-shell game: intermediates of the extradiol-cleaving catechol dioxygenases.  

PubMed

Extradiol-cleaving catechol dioxygenases function by binding both the organic substrate and O2 at a divalent metal center in the active site. They have proven to be a particularly versatile group of enzymes with which to study the O2 activation process. Here, recent studies of homoprotocatechuate 2,3-dioxygenase are summarized, showing how nature can utilize the enzyme structure and the properties of the metal and the substrate to select among many possible chemical paths to achieve both specificity and efficiency. Possible intermediates in the mechanism have been trapped by swapping active-site metals, introducing active-site amino acid substituted variants, and using substrates with different electron-donating capacities. Although each of these intermediates could form part of a viable reaction pathway, kinetic measurements significantly limit the likely candidates. Structural, kinetic, spectroscopic, and computational analyses of the various intermediates shed light on how catalytic efficiency can be achieved. PMID:24615282

Fielding, Andrew J; Lipscomb, John D; Que, Lawrence

2014-06-01

309

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

310

Catechol O-methyltransferase pharmacogenomics and selective serotonin reuptake inhibitor response.  

PubMed

We applied a systematic pharmacogenetic approach to investigate the role of genetic variation in the gene encoding catechol O-methyltransferase (COMT) in individual variation in selective serotonin reuptake inhibitor (SSRI) response among depressed patients. In all, 23 single-nucleotide polymorphisms (SNPs) in COMT were genotyped using DNA from the Sequenced Treatment Alternatives to Relieve Depression (STAR(*)D) study (N=1914). One SNP, rs13306278, located in the distal promoter region of COMT, showed significant association with remission in White non-Hispanic (WNH) subjects (P=0.038). Electromobility shift assay for rs13306278 showed alternation in the ability of the variant sequence to bind nuclear proteins. A replication study was performed using samples from the Mayo Clinic Pharmacogenetics Research Network Citalopram/Escitalopram Pharmacogenomic study (N=422) that demonstrated a similar trend for association. Our findings suggest that novel genetic markers in the COMT distal promoter may influence SSRI response phenotypes. PMID:20877297

Ji, Y; Biernacka, J; Snyder, K; Drews, M; Pelleymounter, L L; Colby, C; Wang, L; Mrazek, D A; Weinshilboum, R M

2012-02-01

311

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

312

The composition of milk xanthine oxidase  

PubMed Central

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

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

1970-01-01

313

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

314

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

PubMed Central

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.

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

315

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

316

Diversity of the Ty1 copia retrotransposon Tos17 in rice ( Oryza sativa L.) and the AA genome of the Oryza genus  

Microsoft Academic Search

Retrotransposons are mobile genetic elements, ubiquitous in Eukaryotic genomes, which have proven to be major genetic tools\\u000a in determining phylogeny and structuring genetic diversity, notably in plants. We investigate here the diversity of the Ty1-copia\\u000a retrotransposon Tos17 in the cultivated rice of Asian origin (Oryza sativa L.) and related AA genome species of the Oryza genus, to contribute understanding of

Julie Petit; Emmanuelle Bourgeois; Wilfried Stenger; Martine Bčs; Gaétan Droc; Donaldo Meynard; Brigitte Courtois; Alain Ghesquičre; François Sabot; Olivier Panaud; Emmanuel Guiderdoni

2009-01-01

317

Ketoglutarate transport protein KgtP is secreted through the type III secretion system and contributes to virulence in Xanthomonas oryzae pv. oryzae.  

PubMed

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 PXO99(A) 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; Chen, Xiao-Bin; Chen, Gong-You

2012-08-01

318

Interspecific Variation of Tetrazolium Oxidase in Sebastodes (Rockfish).  

National Technical Information Service (NTIS)

Fifteen species of Sebastodes were separated into three groups on the bais of mobility of tetrazolium oxidase in starch gels. An apparent relation was observed between tetrazolium oxidase mobility and spawning season. (Author)

A. G. Johnson F. M. Utter H. O. Hodgins

1970-01-01

319

Purification of the Alpha Glycerophosphate Oxidase from African Trypanosomes.  

National Technical Information Service (NTIS)

The bloodstream forms of African trypanosomes are completely dependent on glycolysis for their energy supply and utilize a unique shuttle, glycerophosphate oxidase, which includes a terminal oxidase, to reoxidize the glycolytically produced NADH. This ter...

G. C. Hill

1989-01-01

320

Effect of naphthalene on cytochrome oxidase activity  

SciTech Connect

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

Harmon, H.J.

1988-01-01

321

Generating disulfides with the quiescin sulfhydryl oxidases  

PubMed Central

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

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

2008-01-01

322

[Expression of endopolygalacturonase A of Aspergillus oryzae in Escherichia coli].  

PubMed

Pectinases are mainly used in the food industry to clarify fruit juices and wine, improve oil extraction, remove the peel from the citrus fruit, increase the firmness of some fruits and degum fibres. The filamentous fungus Aspergillus oryzae, used for the production of traditional fermented foods, only could produce less pectinases under general conditions. So far only a few of PGs expressed in yeast or E. coli were reported but they did not show higher activity. The cDNA of mature PGA (without signal peptide) was synthesized with specific primers from total RNA of Aspergillus oryzae by RT-PCR. PGA cDNA was ligated into pET-28a( + ) expression vector, creating plasmid pET-28a( + )-pgA. The plasmid pET-28a( + )-pgA was transformed into E. coli Turner (DE3) plac I cells to express PGA heterogeneously. For improving the efficiency of PGA expression in E. coli, the conditions for expression of the PGA in E. coli were optimized. E. coli Turner (DE3) plac I cells with pET-28a( + )-pgA was first cultivated at 37 degrees, 220r/min until OD600nm reached about 0.8. Then, cultivation broth was added with 0.5 mmol/L IPTG and incubated at 15 degrees C, 170r/min for other 24 h for induced-expression of PGA. Our data showed that the activity of recombinant expressed PGA could reach to 70u/mL medium, which is 87.5-fold of the activity of PGA produced in culture of A. oryzae and superior than known recombinant expression amount of PGA reported by other researchers. PMID:17366896

Zhang, Yu-Ling; Zhao, Qing-Xin; Zhu, Hong; Sun, Jing; Han, Feng-Min; Yuan, Sheng

2007-01-01

323

Putative drug targets in Rhizopus oryzae: in-silico insight.  

PubMed

Opportunistic fungal infections, such as zygomycosis, often associated with excessive morbidity and mortality, are increasingly becoming a source of concern worldwide. In the reported investigation, genome analysis of a major opportunistic fungus Rhizopus oryzae was undertaken to identify gene or protein sequences that may serve as targets for therapeutic interventions. Using database of essential genes six proteins were identified. These proteins are implicated in metabolic/cellular pathways, which are more likely to be crucial for target organism's viability. Their utility as potential drug targets is discussed. PMID:24084240

Jain, Chakresh Kumar; Dasgupta, Ankita; Taneja, Naina; Chaubey, Sonal; Gabrani, Reema; Sharma, Sanjeev K; Gupta, Sanjay

2013-01-01

324

Indoloditerpenes from an algicolous isolate of Aspergillus oryzae.  

PubMed

Two new indoloditerpene derivatives asporyzin A (1) and asporyzin B (2), one new indoloditerpene asporyzin C (3), and three known related indoloditerpenes JBIR-03 (4), emindole SB (5), and emeniveol (6) were isolated from an endophytic fungus Aspergillus oryzae, isolated from the marine red alga Heterosiphonia japonica. Their structures were unambiguously established by spectroscopic techniques. In addition, all the isolates were evaluated preliminarily for insecticidal and antimicrobial activities in order to probe into their chemical defensive function. Compound 4 was more active against brine shrimp than the others, and 3 possessed potent activity against Escherichia coli. PMID:20797856

Qiao, Ming-Feng; Ji, Nai-Yun; Liu, Xiang-Hong; Li, Ke; Zhu, Qing-Mei; Xue, Qin-Zhao

2010-10-01

325

Crystals of beta-xylanase from Aspergillus oryzae.  

PubMed

An endo-xylanase was isolated from the culture of fungus Aspergillus oryzae variant D5. The purified enzyme had a molecular weight of 24,000 and the isoelectric point of 3.6. Xylanase crystals were obtained from a polyethylene glycol 6000 solution by the hanging-drop method. Seeding was used for the enlargement of the crystal size. Crystals belong to the monoclinic space group P2(1) with cell dimensions a = 54.9 A, b = 74.5 A, c = 50.8 A, and beta = 108.7 degrees. Crystals diffract beyond 2.5 A resolution. PMID:8464071

Golubev, A M; Kilimnik AYu; Neustroev, K N; Pickersgill, R W

1993-03-20

326

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.

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

327

Properties and function of lysyl oxidase.  

PubMed

Lysyl oxidase catalyzes the oxidation of peptidyl lysine to alpha-aminoadipic-delta-semialdehyde, the precursor to the covalent crosslinkages that stabilize fibers of elastin and collagen. This enzyme contains both copper and a carbonyl cofactor consistent with an o-quinone. The proposed mechanism of action is derived from available kinetic and chemical data and also can account for mechanism-based inhibition of the enzyme by specific monoamines and diamines. Recent evidence for biosynthetic precursors and for the regulation of lysyl oxidase in fibrotic and malignant diseases is discussed. PMID:1680355

Kagan, H M; Trackman, P C

1991-09-01

328

Decreased plasma postheparin diamine oxidase levels in celiac disease  

Microsoft Academic Search

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

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

1988-01-01

329

Cladal relatedness among Aspergillus oryzae isolates and Aspergillus flavus S and L morphotype isolates.  

PubMed

Aspergillus flavus is the main etiological agent for aflatoxin contamination of crops. Its close relative, A. oryzae, does not produce aflatoxins and has been widely used to produce fermented foods. We compared the phylogeny of A. oryzae isolates and L- and S-type sclerotial isolates of A. flavus using single nucleotide polymorphisms in the omtA gene in the aflatoxin biosynthesis gene cluster and deletions in and distal to the norB-cypA intergenic region as phylogenetic signals. Aflatoxin-producing ability and sclerotial size also were weighted in the analysis. Like A. flavus, the A. oryzae isolates form a polyphyletic assemblage. A. oryzae isolates in one clade strikingly resemble an A. flavus subgroup of atoxigenic L-type isolates. All toxigenic S-type isolates closely resemble another subgroup of atoxigenic L-type isolates. Because atoxigenic S-type isolates are extremely rare, we hypothesize that loss of aflatoxin production in S-type isolates may occur concomitantly with a change to L-type sclerotia. All toxigenic L-type isolates, unlike A. oryzae, have a 1.0 kb deletion in the norB-cypA region. Although A. oryzae isolates, like S-type, have a 1.5 kb deletion in the norB-cypA region, none were cladally related to S-type A. flavus isolates. Our results show that A. flavus populations are genetically diverse. A. oryzae isolates may descend from certain atoxigenic L-type A. flavus isolates. PMID:16430983

Chang, Perng-Kuang; Ehrlich, Kenneth C; Hua, Sui-Sheng T

2006-04-25

330

Application of gold nanoparticles/TiO2 modified electrode for the electrooxidative determination of catechol in tea samples.  

PubMed

A gold nanoparticles/TiO(2) composite modified Indium tin oxide (ITO) electrode has been constructed to study the electrochemical behaviour of catechol (CC) and hydroquinone (HQ) using cyclic voltammetry and differential pulse voltammetry (DPV). Increasing of separation of the oxidative peak potentials and peak current for CC and HQ in pH 6.0 phosphate buffer solution (PBS), make it suitable for selected determination of CC. After the optimization of the conditions, CC was determined by DPV and the linear range is from 1.0×10(-7) to 5.0×10(-4) mol L(-1) with a correlation coefficient of 0.999 and limit of detection as 5.0×10(-8) mol L(-1). Interference and stability study showed a satisfactory result. The proposed method has been applied to determine catechol in tea samples, and comparing with the chromatography the results are satisfactory. PMID:22868112

Wang, Guangfeng; He, Xiuping; Zhou, Fei; Li, Zejun; Fang, Bin; Zhang, Xiaojun; Wang, Lun

2012-11-15

331

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

Microsoft Academic Search

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

M.-A Carsol; M Mascini

1999-01-01

332

The plasma membrane NADH oxidase of HeLa cells has hydroquinone oxidase activity  

Microsoft Academic Search

The plasma membrane NADH oxidase activity partially purified from the surface of HeLa cells exhibited hydroquinone oxidase activity. The preparations completely lacked NADH:ubiquinone reductase activity. However, in the absence of NADH, reduced coenzyme Q10 (Q10H2=ubiquinol) was oxidized at a rate of 15±6 nmol min?1 mg protein?1 depending on degree of purification. The apparent Km for Q10H2 oxidation was 33 ?M.

Takeo Kishi; Dorothy M. Morré; D. James Morré

1999-01-01

333

Monoamine Oxidase Expression During Development and Aging  

Microsoft Academic Search

Monoamine oxidase (MAO) isoenzymes play a major role in regulating the concentration of several bioactive amines, including serotonin and catecholamines. Both in the nervous system and in peripheral organs, MAOs can potentially modulate all the processes involving these bioactive amines. In the present article, we review some of the most significant articles published so far on changes in MAOs during

Antonietta Nicotra; Federica Pierucci; Hasan Parvez; Ornella Senatori

2004-01-01

334

A novel proteolytic processing of prolysyl oxidase  

PubMed Central

Lysyl oxidase (LOX) is an amine oxidase that is critical for the stability of connective tissues. The secreted proLOX is enzymatically quiescent and is activated through proteolytic cleavage between residue Gly162 and Asp163 (residue numbers according to the mouse LOX) by bone morphogenetic protein (BMP)-1 gene products. Here we report a novel processing of proLOX identified in vitro and in vivo. Two forms of mature LOX were identified and characterized by their immunoreactivity to specific antibodies, amine oxidase activity and mass spectrometry. One form was identified as a well characterized BMP-1 processed LOX protein. Another was found to be a truncated form of LOX (tLOX) resulting from the cleavage at the carboxy terminus of Arg192. The tLOX still appeared to retain amine oxidase activity. The results from the proLOX gene deletion and mutation experiments indicated that the processing occurs independent of the cleavage of proLOX by BMP-1 gene products and likely requires the presence of LOX propeptide. These results indicate that proLOX could be processed by two different mechanisms producing two forms of active LOX.

Atsawasuwan, Phimon; Mochida, Yoshiyuki; Katafuchi, Michitsuna; Tokutomi, Kentaro; Mocanu, Viorel; Parker, Carol E.; Yamauchi, Mitsuo

2012-01-01

335

Characterization of Recombinant Lysyl Oxidase Propeptide  

PubMed Central

Lysyl oxidase enzyme activity is critical for the biosynthesis of mature and functional collagens and elastin. In addition, lysyl oxidase has tumor suppressor activity that has been shown to depend on the propeptide region (LOX-PP) derived from pro-lysyl oxidase (Pro-LOX), and not on lysyl oxidase enzyme activity. Pro-LOX is secreted as a 50 kDa proenzyme, and then undergoes biosynthetic proteolytic processing to active ~30 kDa LOX enzyme and LOX-PP. The present study reports the efficient recombinant expression and purification of rat LOX-PP. Moreover, using enzymatic deglycosylation and DTT derivatization combined with mass spectrometry technologies, it is shown for the first time that rLOX-PP and naturally occurring LOX-PP contain both N- and O-linked carbohydrates. Structure predictions furthermore suggest that LOX-PP is a mostly disordered protein, which was experimentally confirmed in circular dichroism studies. Due to its high isoelectric point and its disordered structure, we propose that LOX-PP can associate with extracellular and intracellular binding partners to affect its known biological activities as a tumor suppressor and inhibitor of cell proliferation.

Vora, Siddharth R.; Guo, Ying; Stephens, Danielle N.; Salih, Erdjan; Vu, Emile D.; Kirsch, Kathrin H.; Sonenshein, Gail E.; Trackman, Philip C.

2010-01-01

336

Characterization of recombinant lysyl oxidase propeptide.  

PubMed

Lysyl oxidase enzyme activity is critical for the biosynthesis of mature and functional collagens and elastin. In addition, lysyl oxidase has tumor suppressor activity that has been shown to depend on the propeptide region (LOX-PP) derived from pro-lysyl oxidase (Pro-LOX) and not on lysyl oxidase enzyme activity. Pro-LOX is secreted as a 50 kDa proenzyme and then undergoes biosynthetic proteolytic processing to active approximately 30 kDa LOX enzyme and LOX-PP. The present study reports the efficient recombinant expression and purification of rat LOX-PP. Moreover, using enzymatic deglycosylation and DTT derivatization combined with mass spectrometry technologies, it is shown for the first time that rLOX-PP and naturally occurring LOX-PP contain both N- and O-linked carbohydrates. Structure predictions furthermore suggest that LOX-PP is a mostly disordered protein, which was experimentally confirmed in circular dichroism studies. Due to its high isoelectric point and its disordered structure, we propose that LOX-PP can associate with extracellular and intracellular binding partners to affect its known biological activities as a tumor suppressor and inhibitor of cell proliferation. PMID:20192271

Vora, Siddharth R; Guo, Ying; Stephens, Danielle N; Salih, Erdjan; Vu, Emile D; Kirsch, Kathrin H; Sonenshein, Gail E; Trackman, Philip C

2010-04-01

337

MONOAMINE OXIDASE: RADIOTRACER DEVELOPMENT AND HUMAN STUDIES  

Microsoft Academic Search

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.).

J. S. FOWLER; J. LOGAN; N. D. VOLKOW; G. J. WANG; R. R. MACGREGOR; Y. S. DING

2000-01-01

338

Monoamine oxidase: radiotracer development and human studies.  

National Technical Information Service (NTIS)

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...

Fowler Logan Volkow Wang MacGregor Ding

2000-01-01

339

A novel proteolytic processing of prolysyl oxidase.  

PubMed

Lysyl oxidase (LOX) is an amine oxidase that is critical for the stability of connective tissues. The secreted proLOX is enzymatically quiescent and is activated through proteolytic cleavage between residues Gly(162) and Asp(163) (residue numbers according to the mouse LOX) by bone morphogenetic protein (BMP)-1 gene products. Here we report a novel processing of proLOX identified in vitro and in vivo. Two forms of mature LOX were identified and characterized by their immunoreactivity to specific antibodies, amine oxidase activity, and mass spectrometry. One form was identified as a well-characterized BMP-1 processed LOX protein. Another was found to be a truncated form of LOX resulting from the cleavage at the carboxy terminus of Arg(192). The truncated form of LOX still appeared to retain amine oxidase activity. The results from the proLOX gene deletion and mutation experiments indicated that the processing occurs independent of the cleavage of proLOX by BMP-1 gene products and likely requires the presence of LOX propeptide. These results indicate that proLOX could be processed by two different mechanisms producing two forms of active LOX. PMID:21591931

Atsawasuwan, Phimon; Mochida, Yoshiyuki; Katafuchi, Michitsuna; Tokutomi, Kentaro; Mocanu, Viorel; Parker, Carol E; Yamauchi, Mitsuo

2011-01-01

340

The First Mammalian Aldehyde Oxidase Crystal Structure  

PubMed Central

Aldehyde oxidases (AOXs) are homodimeric proteins belonging to the xanthine oxidase family of molybdenum-containing enzymes. Each 150-kDa monomer contains a FAD redox cofactor, two spectroscopically distinct [2Fe-2S] clusters, and a molybdenum cofactor located within the protein active site. AOXs are characterized by broad range substrate specificity, oxidizing different aldehydes and aromatic N-heterocycles. Despite increasing recognition of its role in the metabolism of drugs and xenobiotics, the physiological function of the protein is still largely unknown. We have crystallized and solved the crystal structure of mouse liver aldehyde oxidase 3 to 2.9 ?. This is the first mammalian AOX whose structure has been solved. The structure provides important insights into the protein active center and further evidence on the catalytic differences characterizing AOX and xanthine oxidoreductase. The mouse liver aldehyde oxidase 3 three-dimensional structure combined with kinetic, mutagenesis data, molecular docking, and molecular dynamics studies make a decisive contribution to understand the molecular basis of its rather broad substrate specificity.

Coelho, Catarina; Mahro, Martin; Trincao, Jose; Carvalho, Alexandra T. P.; Ramos, Maria Joao; Terao, Mineko; Garattini, Enrico; Leimkuhler, Silke; Romao, Maria Joao

2012-01-01

341

XA27 depends on an amino-terminal signal-anchor-like sequence to localize to the apoplast for resistance to Xanthomonas oryzae pv oryzae.  

PubMed

The rice (Oryza sativa) gene Xa27 confers resistance to Xanthomonas oryzae pv oryzae, the causal agent of bacterial blight disease in rice. Sequence analysis of the deduced XA27 protein provides little or no clue to its mode of action, except that a signal-anchor-like sequence is predicted at the amino (N)-terminal region of XA27. As part of an effort to characterize the biochemical function of XA27, we decided to determine its subcellular localization. Initial studies showed that a functional XA27-green fluorescent protein fusion protein accumulated in vascular elements, the host sites where the bacterial blight pathogens multiply. The localization of XA27-green fluorescent protein to the apoplast was verified by detection of the protein on cell walls of leaf sheath and root cells after plasmolysis. Similarly, XA27-FLAG localizes to xylem vessels and cell walls of xylem parenchyma cells, revealed by immunogold electron microscopy. XA27-FLAG could be secreted from electron-dense vesicles in cytoplasm to the apoplast via exocytosis. The signal-anchor-like sequence has an N-terminal positively charged region including a triple arginine motif followed by a hydrophobic region. Deletion of the hydrophobic region or substitution of the triple arginine motif with glycine or lysine residues abolished the localization of the mutated proteins to the cell wall and impaired the plant's resistance to X. oryzae pv oryzae. These results indicate that XA27 depends on the N-terminal signal-anchor-like sequence to localize to the apoplast and that this localization is important for resistance to X. oryzae pv oryzae. PMID:18784285

Wu, Lifang; Goh, Mei Ling; Sreekala, Chellamma; Yin, Zhongchao

2008-11-01

342

Sensitive simultaneous determination of catechol and hydroquinone using a gold electrode modified with carbon nanofibers and gold nanoparticles  

Microsoft Academic Search

A highly sensitive electrochemical sensor for the simultaneous determination of catechol (CC) and hydroquinone (HQ) was fabricated\\u000a by electrodeposition of gold nanoparticles onto carbon nanofiber film pre-cast on an Au electrode. Both CC and HQ cause a\\u000a pair of quasi-reversible and well-defined redox peaks at the modified electrode in pH 7.0 solution. Simultaneously, the oxidation\\u000a peak potentials of CC and HQ

Zhaohui Huo; Yanli Zhou; Qin Liu; Xulun He; Yong Liang; Maotian Xu

2011-01-01

343

Catechol-O-Methyltransferase and Dopamine-?-HydroxyIase Activity in the Blood Vessels of Hypertensive Rats  

Microsoft Academic Search

Catechol-O-methyltransferase (COMT) activity was measured in the aorta and mesenteric arteries of hypertensive rats. In both spontaneously hypertensive rats (SHR) and uninephrectomized-DOCA salt treated hypertensive rats COMT activity per milligram vascular protein increased. The elevated COMT specific activity may be compensatory to the increased blood pressure and serve to increase catecholamine degradation. In contrast to the degradative enzyme, the activity

Trajko Trajkov; Barry A. Berkowitz; Sydney Spector

1974-01-01

344

Psychological Distress in Fibromyalgia Patients: A Role for Catechol-O-Methyl-Transferase Val158Met Polymorphism  

Microsoft Academic Search

Objective: Fibromyalgia (FM) has been related to biochemical alterations, central pain sensitization and psychological distress. Among genetic and environmental hypotheses, a role was suggested for catechol-O-methyl-transferase (COMT), a modulator in the metabolism of monoaminergic neurotransmitters. Method: This study compared the COMT Val158Met enzyme polymorphism (rs4680) of 198 FM patients to 99 pain-free controls. Psychological and functional aspects were assessed through

Jules Desmeules; Valérie Piguet; Marie Besson; Jocelyne Chabert; Elisabetta Rapiti; Michela Rebsamen; Michel F. Rossier; François Curtin; Pierre Dayer; Christine Cedraschi

2012-01-01

345

Catechol O-Methyltransferase (COMT) mRNA Expression in the Dorsolateral Prefrontal Cortex of Patients with Schizophrenia  

Microsoft Academic Search

Human prefrontal cortical neurons express catechol O-methyltransferase (COMT), an enzyme that inactivates the neurotransmitter dopamine. A functional polymorphism of COMT, Val108\\/158 Met, affects prefrontal function, and the high-activity Val allele has been reported to be a genetic risk factor for schizophrenia. We used in situ hybridization histochemistry to measure mRNA levels of COMT in the dorsolateral prefrontal cortex (DLPFC) of

Mitsuyuki Matsumoto; Cynthia Shannon Weickert; Senda Beltaifa; Bhaskar Kolachana; Jingshan Chen; Thomas M Hyde; Mary M Herman; Daniel R Weinberger; Joel E Kleinman

2003-01-01

346

No associations exist between five functional polymorphisms in the catechol-O-methyltransferase gene and schizophrenia in a Japanese population  

Microsoft Academic Search

Catechol-O-methyltransferase (COMT) is one of the enzymes that degrade catecholamine neurotransmitters including dopamine. The COMT gene is located on 22q11.2, a common susceptibility locus for schizophrenia. Therefore, COMT is a strong functional and positional candidate gene for schizophrenia. A common functional polymorphism (rs4680, Val158Met) has been extensively tested for an association with schizophrenia, but with conflicting results. Recent studies indicate

Ayako Nunokawa; Yuichiro Watanabe; Tatsuyuki Muratake; Naoshi Kaneko; Masataka Koizumi; Toshiyuki Someya

2007-01-01

347

Aversive stimuli lead to differential amygdala activation and connectivity patterns depending on catechol- O-methyltransferase Val158Met genotype  

Microsoft Academic Search

The functional Val158Met polymorphism in the gene coding for the catechol-O-methyltransferase (COMT), the major enzyme degrading the catecholaminergic neurotransmitters dopamine, norepinephrine, and epinephrine, has been associated with differential reactivity in limbic and prefrontal brain areas in response to aversive stimuli. However, studies on COMT-genotype effects on activity of the amygdala, a brain region centrally involved in affective processing, have yielded

B. Rasch; K. Spalek; S. Buholzer; R. Luechinger; P. Boesiger; D. J.-F. de Quervain; A. Papassotiropoulos

2010-01-01

348

Catechol-O-Methyltransferase (COMT) Val158Met Genotype is Associated with BOLD Response as a Function of Task Characteristic  

Microsoft Academic Search

The catechol-O-methyltransferase (COMT) val158met single nucleotide polymorphism (rs4680) has been shown to be associated with brain activation during a number of neurocognitive and emotional tasks. The present study evaluated genotypic associations with brain function during measurement of cognitive stability (prosaccades) and plasticity (antisaccades). A total of 36 healthy volunteers were genotyped for rs4680 and underwent functional magnetic resonance imaging (fMRI)

Ulrich Ettinger; Veena Kumari; David A Collier; John Powell; Sonija Luzi; Tanja M Michel; Olurotimi Zedomi; Steven C R Williams

2008-01-01

349

Catechol O-Methyltransferase (COMT) VAL158MET Functional Polymorphism, Dental Mercury Exposure, and Self-Reported Symptoms and Mood  

Microsoft Academic Search

Associations were evaluated between a functional single nucleotide polymorphism (Val158Met) in the gene encoding the catecholamine catabolic enzyme catechol O-methyltransferase (COMT), dental mercury exposure, and self-reported symptoms and mood among 183 male dentists and 213 female dental assistants. Self-reported symptoms, mood, and detailed work histories were obtained by computerized questionnaire. Spot urine samples were collected and analyzed for mercury concentrations

Nicholas J. Heyer; Diana Echeverria; Michael D. Martin; Federico M. Farin; James S. Woods

2009-01-01

350

Bench-scale and field-scale evaluation of catechol 2,3-dioxygenase specific primers for monitoring BTX bioremediation  

Microsoft Academic Search

The objective of this work was to test a molecular genetic method for in situ monitoring of aerobic benzene, toluene, and xylene (BTX) biodegrading microorganisms. Catechol 2,3-dioxygenase (C23DO) genes occur in bacteria that biodegrade benzene, toluene, xylenes, phenol, biphenyl, and naphthalene. A competitive quantitative polymerase chain reaction (QC-PCR) technique using a single set of primers specific for an entire subfamily

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

2004-01-01

351

Analysis of a functional catechol- O-methyltransferase gene polymorphism in schizophrenia: evidence for association with aggressive and antisocial behavior  

Microsoft Academic Search

We have recently characterized a functional polymorphism in the catechol-O-methyltransferase (COMT) gene that is responsible for substantial variability in COMT enzymatic activity found in humans. A common low-activity variant of the enzyme contains a methionine residue at amino acid 158 of membrane-bound COMT whereas the common high activity variant has a valine at this site. Considering the role of COMT

Rael D. Strous; Nigel Bark; Sam S. Parsia; Jan Volavka; Herbert M. Lachman

1997-01-01

352

Association Between Polymorphisms of the Dopamine Receptor D2 and Catechol-o-Methyl Transferase Genes and Cognitive Function  

Microsoft Academic Search

The dopaminergic neurotransmitter system of the brain is involved in working memory and other cognitive functions. Studies\\u000a suggest an important role for dopamine synthesis and uptake in modulation of human cognitive processes. We studied the association\\u000a between polymorphisms in the catechol-o-methyl transferase (COMT) and dopamine receptor D2 (DRD2) genes and general cognitive ability in a secondary analysis of 2091 men

Jennifer L. Bolton; Riccardo E. Marioni; Ian J. Deary; Sarah E. Harris; Marlene C. Stewart; Gordon D. Murray; F. Gerry R. Fowkes; Jackie F. Price

2010-01-01

353

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

354

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

355

Secretion of Aspergillus oryzae alkaline protease in an osmophilic yeast, Zygosaccharomyces rouxii.  

PubMed

To produce Aspergillus oryzae alkaline protease (Alp) in an osmophilic yeast Zygosaccharomyces rouxii, we constructed an expression plasmid consisting of the Z. rouxii glyceraldehyde-3-phosphate dehydrogenase (GAPDH) promoter, the prepro-Alp cDNA of A. oryzae, the whole sequence of Z. rouxii plasmid pSR1, and the G418 resistant gene. The resulting plasmid, when introduced into Z. rouxii cells, directed the secretion of a large amount (about 300 mg/l) of Alp into the culture medium. The N-terminus and specific activity of the enzyme were identical to those of A. oryzae Alp. PMID:1369295

Ogawa, Y; Tatsumi, H; Murakami, S; Ishida, Y; Murakami, K; Masaki, A; Kawabe, H; Arimura, H; Nakano, E; Motai, H

1990-10-01

356

A synthesis of the phenolic lipid, 3-[(Z)-pentadec-8-enyl] catechol, (15:1)-urushiol.  

PubMed

A synthesis of (15:1)-urushiol, urushiol monoene, 3-[(Z)-pentadec-8-enyl] catechol, 1,2-dihydroxy-3-[(Z)-pentadec-8-enyl] benzene, one of the toxic principles of Rhus toxicodendron and of Rhus vernicifera is described. 6-Chlorohexan-1-ol protected at the OH group with ethyl vinyl ether reacted with 2,3-dimethoxybenzaldehyde in the presence of lithium to give, after removal of the protective group with methanolic 4-toluenesulphonic acid, 1-(2,3-dimethoxyphenyl) heptane-1,7-diol. Catalytic hydrogenolysis in ethanol with palladium-carbon selectively afforded 7-(2,3-dimethoxyphenyl)heptane-1-ol accompanied by a small proportion of the 7-(3-methoxyphenyl)heptane-1-diol, formed by demethoxylation. Reaction of the dimethoxy compound with boron tribromide resulted in both bromination and demethylation to give 7-(2,3-dihydroxyphenyl) heptylbromide. This bromide in tetrahydrofuran (THF) containing hexamethylphosphoric triamide reacted with excess lithium oct-1-yne to give 3-(pentadec-8-enyl)catechol which, by catalytic hydrogenation in ethyl acetate containing quinoline, selectively formed the required cis product, 3-[(Z)-pentadec-8-enyl]catechol which was identical chromatographically and spectroscopically with urushiol monoene separated from the natural product. PMID:12426079

Tyman, John H P; Schofield, Brian G; Khor, Choong H

2002-12-01

357

Molecularly designed layer-by-layer (LbL) films to detect catechol using information visualization methods.  

PubMed

The control of molecular architectures has been exploited in layer-by-layer (LbL) films deposited on Au interdigitated electrodes, thus forming an electronic tongue (e-tongue) system that reached an unprecedented high sensitivity (down to 10(-12) M) in detecting catechol. Such high sensitivity was made possible upon using units containing the enzyme tyrosinase, which interacted specifically with catechol, and by processing impedance spectroscopy data with information visualization methods. These latter methods, including the parallel coordinates technique, were also useful for identifying the major contributors to the high distinguishing ability toward catechol. Among several film architectures tested, the most efficient had a tyrosinase layer deposited atop LbL films of alternating layers of dioctadecyldimethylammonium bromide (DODAB) and 1,2-dipalmitoyl-sn-3-glycero-fosfo-rac-(1-glycerol) (DPPG), viz., (DODAB/DPPG)5/DODAB/Tyr. The latter represents a more suitable medium for immobilizing tyrosinase when compared to conventional polyelectrolytes. Furthermore, the distinction was more effective at low frequencies where double-layer effects on the film/liquid sample dominate the electrical response. Because the optimization of film architectures based on information visualization is completely generic, the approach presented here may be extended to designing architectures for other types of applications in addition to sensing and biosensing. PMID:23356548

Aoki, Pedro H B; Alessio, Priscila; Furini, Leonardo N; Constantino, Carlos J L; Neves, Tácito T A T; Paulovich, Fernando V; de Oliveira, Maria Cristina F; Oliveira, Osvaldo N

2013-06-18

358

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

359

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

360

In situ detection of diamine oxidase activity using enhanced chemiluminescence.  

PubMed

In need of a simple and sensitive method for detection of diamine oxidase (EC 1.4.3.6) activity in connection with diamine oxidase purification from human placenta, we have developed an enhanced chemiluminescence method using putrescine as substrate and horseradish peroxidase and luminol for the detection of the H2O2 produced by diamine oxidase. The method allows direct detection of small amounts of diamine oxidase in serum samples after agarose gel electrophoresis and allows visualization of diamine oxidase activity in tissue sections. Employing this method we have detected diamine oxidase in sera from cow, horse, monkey, rabbit, and pregnant women. On tissue sections from term human placenta diamine oxidase activity was exclusively localized to the maternal side and was concentrated in vessels and fibrinoid areas. PMID:8789157

Bruun, L; Houen, G

1996-01-01

361

The Xanthomonas oryzae pv. oryzae eglXoB endoglucanase gene is required for virulence to rice.  

PubMed

Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of bacterial leaf blight, a serious disease of rice worldwide. A Tn5-based transposon randomly insertional mutant library was previously constructed. By screening mutants against susceptible rice cultivar IR24, four mutants were identified with reduced virulence on rice plants and were found to have Tn5 transposon inserted at an endo-1,4-beta-D glucanase (E.C. 3.2.1.4) gene eglXoB. In planta growth analysis indicated that multiplication of the mutants in rice leaves was greatly reduced comparing to the Xoo wild-type strain. Reverse transcriptase polymerase chain reaction (RT-PCR) showed that the expression of eglXoB was induced in planta. Genetic complementation of these mutants with a functional eglXoB gene restored both virulence and in planta growth, suggesting that the eglXoB gene was required for virulence. Ectopic expression of eglXoB in Escherichia coli demonstrated its endoglucanase activity. Otherwise, the growth of the mutants in synthetic medium containing cellulose as the sole sugar source was not affected. Data of this study suggested eglXoB gene is required for pathogenesis of rice bacterial blight disease. PMID:17326805

Hu, Jun; Qian, Wei; He, Chaozu

2007-04-01

362

Two coiled-coil regions of Xanthomonas oryzae pv. oryzae harpin differ in oligomerization and hypersensitive response induction.  

PubMed

Hpa1(Xoo) (harpin) is a type III secreted protein of the rice blight bacterial pathogen Xanthomonas oryzae pv. oryzae that elicits a hypersensitive response (HR) in nonhost tobacco. Hpa1(Xoo) is predicted to contain two potential coiled-coil (CC) regions, one at the N-terminus with a high probability of formation, and one at the C-terminus with a lower probability of formation. We constructed several CC-equivalent peptides by a chemosynthetic method, and investigated the structure-function of the predicted Hpa1(Xoo) CC regions, using biophysical and biochemical approaches. Both peptides elicited an HR in tobacco. Mutant versions of the N- and C-terminal peptides that were predicted to disrupt or favor CC formation were generated. The resulting altered HR activity and oligomerization indicated that the N-terminal CC region is essential for eliciting HR, but the C-terminus is not. The results also indicate that a 14-residue fragment (LDQLLCQLISALLQ) within the N-terminal CC region is a minimal and independent functional element for HR-induction in tobacco leaves. We propose that HR-induction requires a specific oligomerization of the CC regions of Hpa1(Xoo). PMID:20532949

Ji, Zhaolin; Song, Congfeng; Lu, Xuzhong; Wang, Jinsheng

2011-02-01

363

Transcriptional profiling of indica rice cultivar IET8585 (Ajaya) infected with bacterial leaf blight pathogen Xanthomonas oryzae pv oryzae.  

PubMed

An indica rice cultivar IET8585 (Ajaya) resists diverse races of the Xanthomonas oryzae pv oryzae pathogen attack, and is often cultivated as bacterial leaf blight (blb) resistant check in India. Earlier we reported a recessive blb resistance gene mapped to the long arm of chromosome 5 in IET8585. Recessive gene-mediated blb resistance mechanism is not yet clearly understood. Here we analyzed the transcriptional profile of the blb infected resistant cultivar by rice 22K oligo array. Microarray analysis revealed differential expression of numerous genes at both early (6 h) and late (120 h) stages of infection in the resistant IET8585 cultivar over the susceptible IR24. Some of the differential gene expressions were validated by both RT-PCR and Western blot analysis. Higher expression of ethylene response element binding protein (EREBP) transcription factor along with lower expression of alcohol dehydrogenase gene and reactive oxygen species (ROS) scavenging system may be responsible for hypersensitive cell death in the resistant cultivar upon bacterial infection. Induction of glutathione-mediated detoxification and flavonoid biosynthetic pathways along with up-regulation of defense genes during infection may inhibit pathogen spread in the host tissues. In light of this and previous studies a mechanism of recessive gene-mediated bacterial blight resistance in indica rice is discussed. PMID:17870590

Kottapalli, Kameswara Rao; Rakwal, Randeep; Satoh, Kouji; Shibato, Junko; Kottapalli, Pratibha; Iwahashi, Hitoshi; Kikuchi, Shoshi

2007-01-01

364

Recombinant expression, purification, and characterization of XorKII: a restriction endonuclease from Xanthomonas oryzae pv. oryzae.  

PubMed

An endonuclease from Xanthomonas oryzae pathovar oryzae (Xoo) KACC10331, XorKII, was recombinantly produced in Escherichia coli by applying the stationary state induction method, which was necessary to prevent the unwanted lysis of E. coli cells. XorKII was purified by immobilized metal affinity chromatography on an FPLC system. The yield was 3.5mg of XorKII per liter of LB medium. The purified recombinant XorKII showed that it recognized and cleaved to the same site as PstI. It behaved as a dimer as evidenced by the size exclusion chromatography. The specific activity of the purified XorKII was determined to be 31,300 U/mg. The enzyme activity was monitored by cleaving lambda DNA or YEp24 plasmid as substrates. The enzyme was the most active at 10mM Tris-HCl pH 7.0, 10 mM MgCl(2), 1mM dithiothreitol at 37 degrees C. XorKII was easily inactivated by heating at 65 degrees C for 5 min, but retained most of the original activity after incubation at 37 degrees C for 24h. PMID:18793728

Moon, Won Jae; Cho, Jae-Yong; Chae, Young Kee

2008-12-01

365

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

PubMed Central

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

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

2013-01-01

366

Different Roles of the Two High-Oxygen-Affinity Terminal Oxidases of Brucella suis: Cytochrome c Oxidase, but Not Ubiquinol Oxidase, Is Required for Persistence in Mice?  

PubMed Central

The survival of Brucella suis mutant strains in mice demonstrated different roles of the two high-oxygen-affinity terminal oxidases. The cbb3-type cytochrome c oxidase was essential for chronic infection in oxygen-deficient organs. Lack of the cytochrome bd ubiquinol oxidase led to hypervirulence of bacteria, which could rely on nitrite accumulation inhibiting the inducible nitric oxide synthase of the host.

Jimenez de Bagues, Maria Pilar; Loisel-Meyer, Severine; Liautard, Jean-Pierre; Jubier-Maurin, Veronique

2007-01-01

367

Comparative genomic analysis of Aspergillus oryzae strains 3.042 and RIB40 for soy sauce fermentation.  

PubMed

The filamentous fungus Aspergillus oryzae 3.042 (Chinese strain) is a close relative of A. oryzae RIB40 (Japanese strain), which is the important agent used for soy sauce fermentation. The genome of A. oryzae 3.042 was sequenced and compared with A. oryzae RIB40 in an attempt to understand why different soy sauce flavors are produced by these strains. The A. oryzae 3.042 chromosome is 36,547,279bp and contains 11,399 protein-encoding genes. MUMmer analysis revealed that the genomes of A. oryzae 3.042 and RIB40 are mostly collinear. Genome sequence data and comparative analysis of the two strains identified several strain-specific genes that encode putative proteins involved in cell growth, salt tolerance, environmental resistance and flavor formation. A. oryzae 3.042 showed stronger potential for mycelial growth. Some genes unique to A. oryzae RIB40 were related to salt tolerance, especially genes for K(+) transport, while others were associated with ester formation and amino acid metabolism, which likely contribute to flavor formation. In conclusion, comparative genome analysis provided insights into the different genetic traits of the two A. oryzae strains. The unique genes that we found in A. oryzae would make sense to the soy sauce fermentation. PMID:23673060

Zhao, Guozhong; Yao, Yunping; Wang, Chunling; Hou, Lihua; Cao, Xiaohong

2013-06-17

368

Structural mechanism of S-adenosyl methionine binding to catechol O-methyltransferase.  

PubMed

Methyltransferases possess a homologous domain that requires both a divalent metal cation and S-adenosyl-L-methionine (SAM) to catalyze its reactions. The kinetics of several methyltransferases has been well characterized; however, the details regarding their structural mechanisms have remained unclear to date. Using catechol O-methyltransferase (COMT) as a model, we perform discrete molecular dynamics and computational docking simulations to elucidate the initial stages of cofactor binding. We find that COMT binds SAM via an induced-fit mechanism, where SAM adopts a different docking pose in the absence of metal and substrate in comparison to the holoenzyme. Flexible modeling of the active site side-chains is essential for observing the lowest energy state in the apoenzyme; rigid docking tools are unable to recapitulate the pose unless the appropriate side-chain conformations are given a priori. From our docking results, we hypothesize that the metal reorients SAM in a conformation suitable for donating its methyl substituent to the recipient ligand. The proposed mechanism enables a general understanding of how divalent metal cations contribute to methyltransferase function. PMID:21904625

Tsao, Douglas; Diatchenko, Luda; Dokholyan, Nikolay V

2011-01-01

369

Polyoxometalate/laccase-mediated oxidative polymerization of catechol for textile dyeing.  

PubMed

The synergistic effect between polyoxometalates (POMs), namely K(5)[SiW(11)V(V)O(40)]·11H(2)O and H(5)[PMo(10)V(V) (2)O(40)]·13H(2)O and laccase from ascomycete Myceliophthora thermophila has been employed for the first time in oxidative polymerization of catechol. Such a laccase-mediator system allowed the formation of a relatively high molecular weight polycatechol as confirmed by size exclusion chromatography and electrospray ionization mass spectrometry (ESI-MS) (3990 Da when using K(5)[SiW(11)V(V)O(40)]·11H(2)O and 3600 Da with H(5)[PMo(10)V(V) (2)O(40)]·13H(2)O). The synthesized polymers were applied as dyes for the dyeing of flax fabrics. The color intensity of flax fabrics colored with polymer solutions was evaluated by diffuse reflectance spectrophotometry via k/s measurements (+10% of fixation ratio). A new synthetic process allowed a dyeing polymer, provided upon flax coloration, better color fixation and color resistance when compared to that obtained by conventional synthesis with laccase solely or with addition of organic mediator (1-hydroxybenzotriazole). PMID:20953600

Kim, Suyeon; Silva, Carla; Evtuguin, Dmitry V; Gamelas, José A F; Cavaco-Paulo, Artur

2011-02-01

370

Catechol-O-methyltransferase Val158Met polymorphism and breast cancer risk in Asian population.  

PubMed

The association between the polymorphism of catechol-O-methyltransferase (COMT) Val158Met and breast cancer risk is still inconclusive. We performed a meta-analysis to derive a more precise estimation of the relationship. A total of 18 studies including 5,175 cases and 6,463 controls were involved in this meta-analysis. When all studies were pooled into the meta-analysis, no significantly elevated breast cancer risk was associated with all genetic models (for additive model: OR?=?1.273, 95% CI?=?0.947-1.711, P heterogeneity?=?0.000; P?=?0.110; for dominant model: OR?=?1.080, 95% CI?=?0.945-1.234, P heterogeneity?=?0.001; P?=?0.259; for recessive model: OR?=?1.242, 95% CI?=?0.941-1.641, P heterogeneity?=?0.000; P?=?0.126; for allele comparison model: OR?=?1.096, 95% CI?=?0.976-1.230, P heterogeneity?=?0.000; P?=?0.121). In the subgroup analysis by controls source, the same results were found in all genetic models. In summary, this meta-analysis suggests that the COMT Val158Met polymorphism is not a risk factor for breast cancer development. However, large sample and representative population-based studies with homogeneous breast cancer patients and well-matched controls are warranted to confirm this finding. PMID:24146281

Li, Kai; Li, Wusheng; Zou, Huawei

2014-03-01

371

Association between the catechol-O-methyltransferase Val158Met polymorphism and cocaine dependence.  

PubMed

Dopaminergic brain systems have been documented to have a major role in drug reward, thus making genes involved in these circuits plausible candidates for susceptibility to substance use disorders. The catechol-O-methyltransferase (COMT) is involved in the degradation of catecholamines and a functional polymorphism (Val158Met) has been suggested to influence enzyme activity. In this study we hypothesize that genetic variation in the COMT gene contributes to increased risk for cocaine dependence. Cocaine-dependent individuals (n=330) and screened unaffected normal controls (n=255) were genotyped for three SNPs in the COMT gene (rs737865, rs4680 (Val158Met), rs165599). All cases and controls were of African descent. Genotype and allele frequencies differed significantly for the Val158Met polymorphism between cases (f(Met)=35%) and controls (f(Met)=27%) (p=0.004; corrected p=0.014; OR 1.44; 95% CI 1.12-1.86). Haplotype analysis showed a significant association for a two-marker haplotype rs737865-Val158Met (p=0.005). Results suggest that variation in COMT increases risk for cocaine dependence. The low enzyme activity 158Met allele or haplotypes containing this variant might have functional effects on dopamine-derived reward processes and cortical functions resulting in increased susceptibility for cocaine dependence. Additional studies are required to elucidate the role of COMT in the pathophysiology of substance use disorders. PMID:18704099

Lohoff, Falk W; Weller, Andrew E; Bloch, Paul J; Nall, Aleksandra H; Ferraro, Thomas N; Kampman, Kyle M; Pettinati, Helen M; Oslin, David W; Dackis, Charles A; O'Brien, Charles P; Berrettini, Wade H

2008-12-01

372

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.

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

2014-01-01

373

Self-assembly of catecholic macroinitiator on various substrates and surface-initiated polymerization.  

PubMed

A catechol-containing macroinitiator has been designed for the surface-initiated atom transfer radical polymerization (SI-ATRP) from various substrates at ambient temperature. Temperature-sensitive poly(N-isopropyl acrylamide) (PNIPAM) brushes were successfully grafted from a range of substrates surfaces, including metals and polyimides, via SI-ATRP using the resulting macroinitiator, which were characterized by X-ray photoelectron spectroscopy (XPS), water contact angle measurements, and atomic force microscopy (AFM). Effects of the temperature response behavior of PNIPAM brushes on the water contact angles and the impedance of the modified surfaces were also exhibited. The self-assembled film of macroinitiator and the resulting polymer brushes were both stable to soaking of basic solvents, and the brushes did not show any exfoliation or delamination even after 2 h of ultrasonic test. The advantages of the macroinitiator in strong interactions with surfaces and high stability and convenience make it possible to modify the native materials with polymer brushes in a convenient and nondestructive way. Importantly, the macroinitiator is compatible with microcontact printing, and patterned polymer brushes on Ti plate were demonstrated by microcontact printing of BrDOPAMA and the following SI-ATRP. PMID:22204660

Wang, Xiaolong; Ye, Qian; Gao, Tingting; Liu, Jianxi; Zhou, Feng

2012-02-01

374

RpoN (sigma 54) is required for conversion of phenol to catechol in Acinetobacter calcoaceticus.  

PubMed Central

Members of the sigma 54 protein family, encoded by rpoN, are required for the transcription of genes associated with specialized metabolic functions. The ability to grow with phenol appears to be a specialized trait because it is expressed by few of the microorganisms that grow with catechol, the metabolic product of phenol monooxygenase. A mutation preventing the expression of phenol monooxygenase in the bacterial strain Acinetobacter calcoaceticus NCIB8250 was complemented by wild-type DNA segments containing an open reading frame encoding a member of the sigma 54 protein family. DNA sequencing revealed a second open reading frame, designated ORF2, directly downstream of A. calcoaceticus rpoN. The locations of both ORF2 and the 113-residue amino acid sequence of its product are highly conserved in other bacteria. The mutation preventing the expression of rpoN results in an opal codon that terminates the translation of RpoN at a position corresponding to Trp-91 in the 483-residue amino acid sequence of the wild-type protein. Negative autoregulation of rpoN was suggested by the fact that the mutation inactivating RpoN enhanced the transcription of rpoN. Primer extension revealed independent transcription start sites for rpoN and ORF2. Images

Ehrt, S; Ornston, L N; Hillen, W

1994-01-01

375

In vivo catechol activity in the rat locus coeruleus following different nociceptive stimuli and naloxone.  

PubMed

The nucleus locus coeruleus (LC) has been implicated in the processing of spinal reflexes following noxious stimuli. It has been demonstrated that noxious stimuli activate LC neuronal firing, but little is known about the neurochemical changes that might occur following such activation. To determine the effects of different noxious stimuli on LC neuronal activity, anaesthetized rats were exposed to mechanical (tail pinch), thermal (55 degrees C water), and chemical (5% Formalin injected in the hind paw) stimuli; the catechol oxidation current (CA.OC), an index of noradrenergic neuronal activity, in the locus coeruleus was monitored using differential normal pulse voltammetry. In addition, the effect of the opioid antagonist naloxone on the CA.OC in the LC was examined. Exposure to both mechanical and chemical stimuli significantly increased CA.OC indicating an increase in LC noradrenergic neuronal activity, while the thermal stimulus had no effect. Treatment with naloxone (1 mg/kg i.v.) had no effect on CA.OC in the LC. The results show a differential responsiveness of LC noradrenergic neurons to different modes of noxious stimuli and fail to demonstrate a tonic opioid regulation of these neurons in the anaesthetized rat. PMID:1335354

Hong, M; Milne, B; Loomis, C W; Jhamandas, K

1992-08-01

376

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.

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

377

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.

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

378

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

379

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.

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

2010-01-01

380

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

381

A comparison of dopamine agonists and catechol-O-methyltransferase inhibitors in Parkinson's disease.  

PubMed

To compare the efficacy and tolerability of three dopamine agonists--pergolide (PRG), pramipexole (PRX), and ropinirole (ROP)-and two catechol-O-methyltranferase (COMT) inhibitors-tolcapone (TOL) and entacapone (ENT)-as add-on therapies to levodopa (L-Dopa) in Parkinson's disease, we analyzed randomized, double-blind, placebo-controlled, multicenter studies. To our knowledge, they had not yet been evaluated in comparison with each other. Statistical analyses used odds ratios, numbers needed to harm, and Fisher's inverse chi2 method. Seven studies meeting the inclusion criteria included treatment of 1,756 patients. The common efficacy measures were the reduction of L-Dopa dose and "off' duration. The reported reduction in L-Dopa dose was significant for all drugs in relation to placebo, but was most significant for PRX and ENT (p < 0.0001). The most significant reduction in "off' duration was with PRG, PRX, and ENT (p < 0.001). The common tolerability measures were the percentage of patients withdrawn because of side effects, because of any reason, and because of the development of dyskinesias. Ropinirole, PRX, and ENT caused fewer withdrawals related to side effects. Pergolide was better than other analyzed drugs concerning withdrawals for any reason. All drugs caused more dyskinesias than placebo (p < 0.0001), with overlapping confidence intervals, except for TOL 600 mg, which caused more dyskinesias than dopamine agonists and ENT. Pramipexole and ENT had the best efficacy and tolerability profile in this analysis. PMID:11154093

Inzelberg, R; Carasso, R L; Schechtman, E; Nisipeanu, P

2000-01-01

382

Catechol-O-methyltransferase (COMT) pharmacogenetics in the treatment response phenotypes of major depressive disorder (MDD).  

PubMed

Psychiatry is a specialty where the application of pharmacogenomics approaches is made to the study of interindividual differences in response to antidepressants. It is highly applied for improving patient treatment. Major depressive disorder (MDD) is a common and complex disorder resulting from genetic and environmental interactions. Less than 40% of patients with MDD achieve remission, and even after several treatment trials, one in three patients do not fully recover from MDD. Many clinical and genomic association studies suggested that the catechol-O-methyltransferase (COMT) gene region was an important genetic locus for psychiatric disorders, because of the proposed relationship between its function in catecholaminergic neurotransmission and individual response to antidepressants, and vulnerability to psychiatric disorders. Although a number of COMT single nucleotide polymorphisms (SNPs) were observed, the Val108/158Met (rs4680) polymorphism in exon 4 resulted in a change in the enzyme structure which has been intensively investigated in relation to its role of enzyme activity and processes of prefrontal cortex functions in cognition. As serotonin interacts with dopamine and dopamine availability is influenced by COMT SNPs, an association between the COMT gene and response to treatment, based on the various pharmacogenetics/pharmacogenomics studies about COMT gene published to date, is explored in this overview. PMID:22483292

Kocabas, Neslihan Aygun

2012-05-01

383

Catechol-O-methyltransferase val158met genotype influences neural processing of reward anticipation.  

PubMed

Reward processing depends critically on dopaminergic neurotransmission in the ventral striatum. The common polymorphism val(158)met of catechol-O-methyltransferase (COMT) accounts for significant interindividual variations in dopamine (DA) degradation, although the direct effect of COMT on striatal DA might be limited. Using fMRI we assessed the influence of COMT val(158)met genotype on brain activations elicited by the anticipation of monetary gains and losses in forty-four healthy volunteers. We found that the met(158) allele, which is presumably linked to higher synaptic DA levels, was associated with higher responses in ventral striatum to loss incentives. There was a linear relationship between the number of met(158) alleles and ventral striatal activity. Furthermore, we observed a similar gene-dose effect in the anterior temporal cortex, a region that has been linked to the coupling of sensory information with emotional contents. Temporal cortex also showed enhanced connectivity to the ventral striatum during the processing of incentive stimuli. Increased ventral striatal reactivity to loss incentives related to the met(158) allele might contribute to the observed association of the met(158) allele to higher loss aversion behaviour. Current evidence and our results are compatible with an interpretation that construes this effect of COMT genotype on striatal reactivity as a result of a cortico-striatal interaction. PMID:18634888

Schmack, Katharina; Schlagenhauf, Florian; Sterzer, Philipp; Wrase, Jana; Beck, Anne; Dembler, Theresa; Kalus, Peter; Puls, Imke; Sander, Thomas; Heinz, Andreas; Gallinat, Jürgen

2008-10-01

384

Laccase biosensor based on electrospun copper/carbon composite nanofibers for catechol detection.  

PubMed

The study compared the biosensing properties of laccase biosensors based on carbon nanofibers (CNFs) and copper/carbon composite nanofibers (Cu/CNFs). The two kinds of nanofibers were prepared by electrospinning and carbonization under the same conditions. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy were employed to investigate the morphologies and structures of CNFs and Cu/CNFs. The amperometric results indicated that the Cu/CNFs/laccase(Lac)/Nafion/glass carbon electrode (GCE) possessed reliable analytical performance for the detection of catechol. The sensitivity of the Cu/CNFs/Lac/Nafion/GCE reached 33.1 ?A/mM, larger than that of CNFs/Lac/Nafion/GCE. Meanwhile, Cu/CNFs/Lac/Nafion/GCE had a wider linear range from 9.95 × 10(-6) to 9.76 × 10(-3) M and a lower detection limit of 1.18 ?M than CNFs/Lac/Nafion/GCE. Moreover, it exhibited a good repeatability, reproducibility, selectivity and long-term stability, revealing that electrospun Cu/CNFs have great potential in biosensing. PMID:24561403

Fu, Jiapeng; Qiao, Hui; Li, Dawei; Luo, Lei; Chen, Ke; Wei, Qufu

2014-01-01

385

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

386

Catechol--an oviposition stimulant for cigarette beetle in roasted coffee beans.  

PubMed

The cigarette beetle, Lasioderma serricorne, is a serious global pest that preys on stored food products. Larvae of the beetle cannot grow on roasted coffee beans or dried black or green tea leaves, although they oviposit on such products. We investigated oviposition by the beetles on MeOH extracts of the above products. The number of eggs laid increased with an increase in dose of each extract, indicating that chemical factors stimulate oviposition by the beetles. This was especially true for \\ coffee bean extracts, which elicited high numbers of eggs even at a low dose (0.1 g bean equivalent/ml) compared to other extracts. Coffee beans were extracted in hexane, chloroform, 1-butanol, MeOH, and 20% MeOH in water. The number of eggs laid was higher on filter papers treated with chloroform, 1-butanol, MeOH, and 20% MeOH in water extracts than on control (solvent alone) papers. The chloroform extract was fractionated by silica-gel column chromatography. Nine compounds were identified by gas chromatography/mass spectrometry from an active fraction. Of these compounds, only a significant ovipositional response to catechol was observed. PMID:24752858

Nagasawa, Atsuhiko; Kamada, Yuji; Kosaka, Yuji; Arakida, Naohiro; Hori, Masatoshi

2014-05-01

387

A novel dsDNA/polydiphenylamine-4-sulfonic acid electrochemical biosensor for selective detection of the toxic catechol and related DNA damage.  

PubMed

A novel biosensor consisting of a glassy carbon electrode (GCE) modified by a polydiphenylamine-4-sulfonic acid (PDPASA, conjugated polymer) film and double-stranded DNA (dsDNA), i.e. dsDNA/PDPASA/GCE, was researched and developed for the analysis of catechol - a potentially toxic substance for humans and the environment. The surface properties of the PDPASA film, particularly after dsDNA was immobilized on it, were characterized with the use of atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The surfaces of the novel DNA/PDPASA/GCE biosensor changed during the fabrication process and displayed high sensitivity for catechol. The oxidation potential of catechol decreased significantly and the corresponding current increased substantially as compared with the values obtained at the GCE alone and at the dsDNA/GCE. Also, with the addition of hydroquinone, two well discriminated CV peaks were obtained, and it was demonstrated that hydroquinone did not interfere with catechol. DPV analysis produced a linear catechol calibration (range: 0.750 to 8.25 × 10(-6) mol L(-1); detection limit: 6.48 × 10(-7) mol L(-1)), and thus, various water samples were analysed successfully by this novel method. In addition, the DNA/PDPASA/GCE was used to study DNA damage in the presence of catechol with the use of the Co(phen)(3)(3+) electroactive probe. Results indicated that the potentially toxic catechol and its metabolites were all responsible for DNA damage. PMID:23259155

Wang, Pingping; Ni, Yongnian; Kokot, Serge

2013-02-21

388

Multistate CASPT2 study of native iron(III)-dependent catechol dioxygenase and its functional models: electronic structure and ligand-to-metal charge-transfer excitation.  

PubMed

We theoretically investigated the ligand-to-metal charge-transfer (LMCT) excitation of the native iron(III)-dependent catechol dioxygenase and its functional model complexes with multistate complete active space second-order perturbation theory (MS-CASPT2) because the LMCT (catecholate-to-iron(III) charge-transfer) excitation energy is believed to relate to the reactivity of the native enzyme and its functional model complexes. The ground state calculated by the MS-CASPT2 method mainly consists of the iron(III)-catecholate electron configuration and moderately of the iron(II)-semiquinonate electron configuration for both of the enzyme active centers and the model complexes when the active center exists in the protein environment and the model complexes exist in the solution. However, the ground-state wave function mainly consists of the iron(II)-semiquinonate electron configuration for both the enzyme active site without a protein environment and the model complexes in vacuo. These results clearly show that the protein environment and solvent play important roles to determine the electronic structure of the catecholatoiron(III) complex. The LMCT excitation energy clearly relates to the weight of the iron(III)-catecholate configuration in the ground state. The reactivity and the LMCT excitation energy directly relate to the ionization potential of the catecholate (IP(CAT)) in the model complex. This is because the charge transfer from the catecholate moiety to the dioxygen molecule plays a key role to activate the dioxygen molecule. However, the reactivity of the native catechol dioxygenase is much larger than those of the model complexes, despite the similar IP(CAT) values, suggesting that other factors such as the coordinatively unsaturated iron(III) center of the native enzyme play a crucial role in the reactivity. PMID:21462943

Nakatani, Naoki; Hitomi, Yutaka; Sakaki, Shigeyoshi

2011-04-28

389

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

Microsoft Academic Search

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

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

2008-01-01

390

Purification and characterization of the pectin lyase produced by Rhizopus oryzae grown on orange peels  

Microsoft Academic Search

Potentiality of Rhizopus oryzae to utilize orange peels under solid state fermentation conditions to produce macerating fluid with high cellulolytic and pectinolytic activities were confirmed in this work. Addition of NH4NO3 and NH4Cl to the fermentation medium improved the macerating potentiality due to an increase in enzyme levels. The pectin lyase (PL) secreted by R. oryzae under these conditions was

Hossam S. HAMDY

391

SSRs for Marker-Assisted Selection for Blast Resistance in Rice ( Oryza sativa L.)  

Microsoft Academic Search

Rice blast caused by the fungus Magnaporthe oryzae is one of the most devastating diseases of rice in nearly all rice growing areas of the world including Malaysia. To develop\\u000a cultivars with resistance against different races of M. oryzae, availability of molecular markers along with marker-assisted selection strategies are essential. In this study, 11 polymorphic\\u000a simple sequence repeat (SSR) markers

Sadegh Ashkani; Mohd Yusop Rafii; Ibrahim Rusli; Meon Sariah; Siti Nor Akmar Abdullah; Harun Abdul Rahim; M. A. Latif

392

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

393

A successful treatment of rhinocerebral mucormycosis due to Rhizopus oryzae  

PubMed Central

Mucormycosis is an invasive fungal infection caused by filamentous fungi of the Mucoraceae family. The genera most commonly responsible are Mucor or Rhizopus. The disease occurs mostly in association with diabetic ketoacidosis. Mucormycosis has an extremely high death rate even when aggressive surgery is done. Death rates range from 25-85% depending on the body area involved. A case of rhinocerebral mucormycosis in a 65-year-old diabetic male patient typically presenting as headache, especially in parietal and frontal lobes, with nose and left eye discharge. After clinical and laboratory examination, mucormycosis was diagnosed, and Rhizopus oryzae was isolated. Systemic therapy with amphotericin B administered intravenously then replaced by posaconazole by a combination of aggressive surgery. The patient was treated and followed up for one year. We emphasize the importance of early detection and aggressive treatment in the management of this fatal disease.

Mohammadi, Rasoul; Nazeri, Mehdi; Sayedayn, Sayed Mohammad Amin; Ehteram, Hassan

2014-01-01

394

A successful treatment of rhinocerebral mucormycosis due to Rhizopus oryzae.  

PubMed

Mucormycosis is an invasive fungal infection caused by filamentous fungi of the Mucoraceae family. The genera most commonly responsible are Mucor or Rhizopus. The disease occurs mostly in association with diabetic ketoacidosis. Mucormycosis has an extremely high death rate even when aggressive surgery is done. Death rates range from 25-85% depending on the body area involved. A case of rhinocerebral mucormycosis in a 65-year-old diabetic male patient typically presenting as headache, especially in parietal and frontal lobes, with nose and left eye discharge. After clinical and laboratory examination, mucormycosis was diagnosed, and Rhizopus oryzae was isolated. Systemic therapy with amphotericin B administered intravenously then replaced by posaconazole by a combination of aggressive surgery. The patient was treated and followed up for one year. We emphasize the importance of early detection and aggressive treatment in the management of this fatal disease. PMID:24672569

Mohammadi, Rasoul; Nazeri, Mehdi; Sayedayn, Sayed Mohammad Amin; Ehteram, Hassan

2014-01-01

395

Cloning and characterization of two flavohemoglobins from Aspergillus oryzae  

SciTech Connect

Two flavohemoglobin (FHb) genes, fhb1 and fhb2, were cloned from Aspergillus oryzae. The amino acid sequences of the deduced FHb1 and FHb2 showed high identity to other FHbs except for the predicted mitochondrial targeting signal in the N-terminus of FHb2. The recombinant proteins displayed absorption spectra similar to those of other FHbs. FHb1 and FHb2 were estimated to be a monomer and a dimer in solution, respectively. Both of the isozymes exhibit high NO dioxygenase (NOD) activity. FHb1 utilizes either NADH or NADPH as an electron donor, whereas FHb2 can only use NADH. These results suggest that FHb1 and FHb2 are fungal counterparts of bacterial FHbs and act as NO detoxification enzymes in the cytosol and mitochondria, respectively. This study is the first to show that a microorganism contains two isozymes of FHb and that intracellular localization of the isozymes could differ.

Zhou Shengmin; Fushinobu, Shinya; Nakanishi, Yoshito; Kim, Sang-Wan; Wakagi, Takayoshi [Department of Biotechnology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657 (Japan); Shoun, Hirofumi [Department of Biotechnology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657 (Japan)], E-mail: ahshoun@mail.ecc.u-tokyo.ac.jp

2009-03-27

396

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

397

Secretion of calf chymosin from the filamentous fungus Aspergillus oryzae.  

PubMed

Active calf chymosin was secreted from Aspergillus oryzae transformants when the chymosin cDNA was expressed under the control of glucoamylase gene (glaA) promoter. Secreted prochymosin was autocatalytically activated to the chymosin (0.07-0.16 mg/l). Western blot analysis showed that a secreted protein immunoreactive with an anti-chymosin antibody was of similar size to authentic chymosin. Northern blot analysis revealed that mRNA of the chymosin cDNA was expressed at as high level as that of the glaA gene. The size and the level of the transcript were different among transformants, due to the integration position of the plasmid on the chromosome. PMID:7764387

Tsuchiya, K; Gomi, K; Kitamoto, K; Kumagai, C; Tamura, G

1993-11-01

398

Transgenic rice plants expressing the ferredoxin-like protein (AP1) from sweet pepper show enhanced resistance to Xanthomonas oryzae pv. oryzae.  

PubMed

We used particle bombardment to cotransform mature seed-derived rice callus (Oryza sativa L., ssp. japonica, cv. Eyi 105) with plasmids containing the linked marker genes gusA and hpt, and the ap1 gene encoding an amphipathic protein previously shown to delay the hypersensitive response induced in non-host plants by the pathogen Pseudomonas syringae pv. syringae (Pss). Thirty-two independent lines of transgenic rice plants were regenerated, and 27 of these lines carried all three transgenes as shown by molecular analysis. A bacterial blight inoculation test was carried out on ten lines. In each case, plants carrying the ap1 gene showed enhanced resistance to Xanthomonas oryzae pv. oryzae (Xoo) race 6 at various levels. This suggests the ap1 gene could be a useful candidate for genetic engineering strategies in rice to provide bacterial blight resistance. PMID:11297801

Tang, K; Sun, X; Hu, Q; Wu, A; Lin, C -H.; Lin, H -J.; Twyman, R M.; Christou, P; Feng, T

2001-04-01

399

Identification and Characterization of ABA Receptors in Oryza sativa  

PubMed Central

Abscisic acid (ABA) is an essential phytohormone that regulates plant stress responses. ABA receptors in Arabidopsis thaliana (AtPYLs) have been extensively investigated by structural, biochemical, and in vivo studies. In contrast, relatively little is known about the ABA signal transduction cascade in rice. Besides, the diversities of AtPYLs manifest that the information accumulated in Arabidopsis cannot be simply adapted to rice. Thus, studies on rice ABA receptors are compulsory. By taking a bioinformatic approach, we identified twelve ABA receptor orthologs in Oryza sativa (japonica cultivar-group) (OsPYLs), named OsPYL1–12. We have successfully expressed and purified OsPYL1–3, 6 and 10–12 to homogeneity, tested the inhibitory effects on PP2C in Oryza sativa (OsPP2C), and measured their oligomerization states. OsPYL1–3 mainly exhibit as dimers and require ABA to inhibit PP2C’s activity. On the contrary, OsPYL6 retains in the monomer-dimer equilibrium state and OsPYL10–11 largely exist as monomers, and they all display an ABA-independent phosphatase inhibition manner. Interestingly, although OsPYL12 seems to be a dimer, it abrogates the phosphatase activity of PP2Cs in the absence of ABA. Toward a further understanding of OsPYLs on the ABA binding and PP2C inhibition, we determined the crystal structure of ABA-OsPYL2-OsPP2C06 complex. The bioinformatic, biochemical and structural analysis of ABA receptors in rice provide important foundations for designing rational ABA-analogues and breeding the stress-resistant rice for commercial agriculture.

He, Yuan; Hao, Qi; Li, Wenqi; Yan, Chuangye

2014-01-01

400

Vacuolar membrane dynamics in the filamentous fungus Aspergillus oryzae.  

PubMed

Vacuoles in filamentous fungi are highly pleomorphic and some of them, e.g., tubular vacuoles, are implicated in intra- and intercellular transport. In this report, we isolated Aovam3, the homologue of the Saccharomyces cerevisiae VAM3 gene that encodes the vacuolar syntaxin, from Aspergillus oryzae. In yeast complementation analyses, the expression of Aovam3 restored the phenotypes of both Deltavam3 and Deltapep12 mutants, suggesting that AoVam3p is likely the vacuolar and/or endosomal syntaxin in A. oryzae. FM4-64 [N-(3-triethylammoniumpropyl)-4-(p-diethylaminophenyl-hexatrienyl)pyridinium dibromide] and CMAC (7-amino-4-chloromethylcoumarin) staining confirmed that the fusion protein of enhanced green fluorescent protein (EGFP) with AoVam3p (EGFP-AoVam3p) localized on the membrane of the pleomorphic vacuolar networks, including large spherical vacuoles, tubular vacuoles, and putative late endosomes/prevacuolar compartments. EGFP-AoVam3p-expressing strains allowed us to observe the dynamics of vacuoles with high resolutions, and moreover, led to the discovery of several new aspects of fungal vacuoles, which have not been discovered so far with conventional staining methods, during different developmental stages. In old hyphae, EGFP fluorescence was present in the entire lumen of large vacuoles, which occupied most of the cell, indicating that degradation of cytosolic materials had occurred in such hyphae via an autophagic process. In hyphae that were not in contact with nutrients, such as aerial hyphae and hyphae that grew on a glass surface, vacuoles were composed of small punctate structures and tubular elements that often formed reticulum-like networks. These observations imply the presence of so-far-unrecognized roles of vacuoles in the development of filamentous fungi. PMID:16467481

Shoji, Jun-ya; Arioka, Manabu; Kitamoto, Katsuhiko

2006-02-01

401

Comparative sequence analysis of MONOCULM1-orthologous regions in 14 Oryza genomes  

PubMed Central

Comparative genomics is a powerful tool to decipher gene and genome evolution. Placing multiple genome comparisons in a phylogenetic context improves the sensitivity of evolutionary inferences. In the genus Oryza, this comparative approach can be used to investigate gene function, genome evolution, domestication, polyploidy, and ecological adaptation. A large genomic region surrounding the MONOCULM1 (MOC1) locus was chosen for study in 14 Oryza species, including 10 diploids and 4 allotetraploids. Sequencing and annotation of 18 bacterial artificial chromosome clones for these species revealed highly conserved gene colinearity and structure in the MOC1 region. Since the Oryza radiation about 14 Mya, differences in transposon amplification appear to be responsible for the different current sizes of the Oryza genomes. In the MOC1 region, transposons were only conserved between genomes of the same type (e.g., AA or BB). In addition to the conserved gene content, several apparent genes have been generated de novo or uniquely retained in the AA lineage. Two different 3-gene segments have been inserted into the MOC1 region of O. coarctata (KK) or O. sativa by unknown mechanism(s). Large and apparently noncoding sequences flanking the MOC1 gene were observed to be under strong purifying selection. The allotetraploids Oryza alta and Oryza minuta were found to be products of recent polyploidization, less than 1.6 and 0.4 Mya, respectively. In allotetraploids, pseudogenization of duplicated genes was common, caused by large deletions, small frame-shifting insertions/deletions, or nonsense mutations.

Lu, Fei; Ammiraju, Jetty S. S.; Sanyal, Abhijit; Zhang, Shengli; Song, Rentao; Chen, Jinfeng; Li, Guisheng; Sui, Yi; Song, Xiang; Cheng, Zhukuan; de Oliveira, Antonio Costa; Bennetzen, Jeffrey L.; Jackson, Scott A.; Wing, Rod A.; Chen, Mingsheng

2009-01-01

402

Aspergillus oryzae-based cell factory for direct kojic acid production from cellulose  

PubMed Central

Background Kojic acid (5-Hydroxy-2-(hydroxymethyl)-4-pyrone) is one of the major secondary metabolites in Aspergillus oryzae. It is widely used in food, pharmaceuticals, and cosmetics. The production cost, however, is too high for its use in many applications. Thus, an efficient and cost-effective kojic acid production process would be valuable. However, little is known about the complete set of genes for kojic acid production. Currently, kojic acid is produced from glucose. The efficient production of kojic acid using cellulose as an inexpensive substrate would help establish cost-effective kojic acid production. Results A kojic acid transcription factor gene over-expressing the A. oryzae strain was constructed. Three genes related to kojic acid production in this strain were transcribed in higher amounts than those found in the wild-type strain. This strain produced 26.4 g/L kojic acid from 80 g/L glucose. Furthermore, this strain was transformed with plasmid harboring 3 cellulase genes. The resultant A. oryzae strain successfully produced 0.18 g/L of kojic acid in 6 days of fermentation from the phosphoric acid swollen cellulose. Conclusions Kojic acid was produced directly from cellulose material using genetically engineered A. oryzae. Because A. oryzae has efficient protein secretion ability and secondary metabolite productivity, an A. oryzae-based cell factory could be a platform for the production of various kinds of bio-based chemicals.

2014-01-01

403

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

PubMed Central

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

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

2010-01-01

404

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

405

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.

2013-01-01

406

OryR is a LuxR-family protein involved in interkingdom signaling between pathogenic Xanthomonas oryzae pv. oryzae and rice.  

PubMed

Xanthomonas oryzae pv. oryzae, the causal agent of bacterial leaf blight in rice, contains a regulator that is encoded in the genome, designated OryR, which belongs to the N-acyl homoserine lactone (AHL)-dependent quorum-sensing LuxR subfamily of proteins. However, we previously reported that X. oryzae pv. oryzae does not make AHLs and does not possess a LuxI-family AHL synthase and that the OryR protein is solubilized by a compound present in rice. In this study we obtained further evidence that OryR interacts with a rice signal molecule (RSM) and that the OryR concentration increases when rice is infected with X. oryzae pv. oryzae. We also describe three OryR target promoters which are regulated differently: (i) the neighboring proline iminopeptidase (pip) virulence gene, which is positively regulated by OryR in the presence of the RSM; (ii) the oryR promoter, which is negatively autoregulated independent of the RSM; and (iii) the 1,4-beta-cellobiosidase cbsA gene, which is positively regulated by OryR independent of the RSM. We also found that the RSM for OryR is small, is not related to AHLs, and is not able to activate the broad-range AHL biosensor Agrobacterium tumefaciens NT1(pZLQR). Furthermore, OryR does not regulate production of the quorum-sensing diffusible signal factor present in the genus Xanthomonas. Therefore, OryR has unique features and is an important regulator involved in interkingdom communication between the host and the pathogen. PMID:19028884

Ferluga, Sara; Venturi, Vittorio

2009-02-01

407

PhyA, a secreted protein of Xanthomonas oryzae pv. oryzae, is required for optimum virulence and growth on phytic acid as a sole phosphate source.  

PubMed

Xanthomonas oryzae pv. oryzae causes bacterial leaf blight, a serious disease of rice. We have identified a novel virulence deficient mutant (BXO1691) of X. oryzae pv. oryzae that has a Tn5 insertion in an open reading frame (phyA; putative phytase A) encoding a 373-amino acid (aa) protein containing a 28-aa predicted signal peptide. Extracellular protein profiles revealed that a 38-kDa band is absent in phyA mutants as compared with phyA+ strains. A BLAST search with phyA and its deduced polypeptide sequence indicated significant similarity with conserved hypothetical proteins in Xanthomonas axonopodis pv. citri and Xanthomonas campestris pv. campestris and limited homology to secreted phytases of Bacillus species. Homology modeling with a Bacillus phytase as the template suggests that the PhyA protein has a similar six-bladed beta-propeller architecture and exhibits conservation of certain critical active site residues. Phytases are enzymes that are involved in degradation of phytic acid (inositol hexaphosphate), a stored form of phosphate in plants. The phyA mutants exhibit a growth deficiency in media containing phytic acid as a sole phosphate source. Exogenous phosphate supplementation promotes migration of phyA X. oryzae pv. oryzae mutants in rice leaves. These results suggest that the virulence deficiency of phyA mutants is, at least in part, due to inability to use host phytic acid as a source of phosphate. phyA-like genes have not been previously reported to be involved in the virulence of any plant pathogenic bacterium. PMID:14601665

Chatterjee, Subhadeep; Sankaranarayanan, Rajan; Sonti, Ramesh V

2003-11-01

408

OryR Is a LuxR-Family Protein Involved in Interkingdom Signaling between Pathogenic Xanthomonas oryzae pv. oryzae and Rice ?  

PubMed Central

Xanthomonas oryzae pv. oryzae, the causal agent of bacterial leaf blight in rice, contains a regulator that is encoded in the genome, designated OryR, which belongs to the N-acyl homoserine lactone (AHL)-dependent quorum-sensing LuxR subfamily of proteins. However, we previously reported that X. oryzae pv. oryzae does not make AHLs and does not possess a LuxI-family AHL synthase and that the OryR protein is solubilized by a compound present in rice. In this study we obtained further evidence that OryR interacts with a rice signal molecule (RSM) and that the OryR concentration increases when rice is infected with X. oryzae pv. oryzae. We also describe three OryR target promoters which are regulated differently: (i) the neighboring proline iminopeptidase (pip) virulence gene, which is positively regulated by OryR in the presence of the RSM; (ii) the oryR promoter, which is negatively autoregulated independent of the RSM; and (iii) the 1,4-?-cellobiosidase cbsA gene, which is positively regulated by OryR independent of the RSM. We also found that the RSM for OryR is small, is not related to AHLs, and is not able to activate the broad-range AHL biosensor Agrobacterium tumefaciens NT1(pZLQR). Furthermore, OryR does not regulate production of the quorum-sensing diffusible signal factor present in the genus Xanthomonas. Therefore, OryR has unique features and is an important regulator involved in interkingdom communication between the host and the pathogen.

Ferluga, Sara; Venturi, Vittorio

2009-01-01

409

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

PubMed Central

Field bean (Dolichos lablab) contains a single isoform of PPO (polyphenol oxidase) – a type III copper protein that catalyses the o-hydroxylation of monophenols and oxidation of o-diphenols using molecular oxygen – and is a homotetramer with a molecular mass of 120 kDa. The enzyme is activated manyfold either in the presence of the anionic detergent SDS below its critical micellar concentration or on exposure to acid-pH. The enhancement of kcat upon activation is accompanied by a marked shift in the pH optimum for the oxidation of t-butyl catechol from 4.5 to 6.0, an increased sensitivity to tropolone, altered susceptibility to proteolytic degradation and decreased thermostability. The Stokes radius of the native enzyme is found to increase from 49.1±2 to 75.9±0.6 Ĺ (1 Ĺ=0.1 nm). The activation by SDS and acid-pH results in a localized conformational change that is anchored around the catalytic site of PPO that alters the microenvironment of an essential glutamic residue. Chemical modification of field bean and sweet potato PPO with 1-ethyl-3-(3-dimethylaminopropyl)carbodi-imide followed by kinetic analysis leads to the conclusion that both the enzymes possess a core carboxylate essential to activity. This enhanced catalytic efficiency of PPO, considered as an inducible defence oxidative enzyme, is vital to the physiological defence strategy adapted by plants to insect herbivory and pathogen attack.

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

2006-01-01

410

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

411

Characterization of polyphenol oxidase in coffee  

Microsoft Academic Search

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

Paulo Mazzafera; Simon P Robinson

2000-01-01

412

Antigenic independence of some microbial urate oxidases.  

PubMed Central

Antisera were prepared to urate oxidase derived from three microbial species, a yeast (Candida utilis), a mold (Aspergillus flavus), and a bacterium (Bacillus fastidious). The antisera inhibited enyme activity to a limited extent. Cross-reaction studies with preparations of the enzyme from these and other species indicated that the microbial enzyme exhibits a high degree of antigenic independence. This appeared to be particularly true of the bacteria studied. Images

Fitzpatrick, D A; McGeeney, K F

1975-01-01

413

Characterization of Glucose Oxidase from Penicillium notatum  

Microsoft Academic Search

Summary In the present study glucose oxidase (GOD) has been isolated from a culture filtrate of Penicillium notatum. The enzyme was purified by ammonium sulphate precipitation, di- ethylaminoethyl (DEAE) cellulose ion-exchange chromatography and Sephadex gel filtra- tion. This protocol gave 16.47-fold purification and 25 % recovery of the enzyme. The opti- mum pH and temperature for the activity were 5.4

Haq Nawaz Bhatti; Nabeela Saleem

2009-01-01

414

Sulfhydryl oxidases: sources, properties, production and applications  

Microsoft Academic Search

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

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

2011-01-01

415

Genetic variation and population structure in Oryza malampuzhaensis Krish. et Chand. endemic to Western Ghats, South India  

Microsoft Academic Search

Oryza malampuzhaensis Krish.et Chand. (2n = 4x = 48; Poaceae,Oryza) is endemic to Western Ghats, South India, and shows a highly localized distribution over a small geographical area in this\\u000a region. This is the most poorly understood taxon in genusOryza and is often misidentified asO. officinalis owing to their close morphology. We assessed the nature and distribution of genetic variation

George Thomas; Sreejayan; Latha Joseph; Philomena Kuriachan

2001-01-01

416

Adsorption of OP 1 -related bacteriophages requires the gene encoding a TonB-dependent receptor-like protein in Xanthomonas oryzae pv. oryzae  

Microsoft Academic Search

Xanthomonas\\u000a oryzae pv. oryzae strain T7174R is lysed by bacteriophage OP1h and OP1h2. Three mutants tolerant to both OP1h and OP1h2 were isolated by transposon mutagenesis. The mutants had an insertion of the transposon in XOO1687, which is predicted to\\u000a encode a TonB-dependent receptor gene. Plasmid pHMIroNB that contained XOO1687 of T7174R was constructed, and the mutant was\\u000a transformed with

Yasuhiro Inoue; Seiji Tsuge; Jun Ohnishi; Takayuki Matsuura; Hirokazu Ochiai; Hisatoshi Kaku; Koji Azegami

2007-01-01

417

D-Amino acid oxidase: new findings.  

PubMed

The most recent research on D-amino acid oxidases and D-amino acid metabolism has revealed new, intriguing properties of the flavoenzyme 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. A novel role in modulating the level of D-serine in brain has also been proposed for the enzyme. At the molecular level, site-directed mutagenesis studies on the pig kidney D-amino acid oxidase and, more recently, on the enzyme from the yeast Rhodotorula gracilis indicated that the few conserved residues of the active site do not play a role in acid-base catalysis but rather are involved in substrate interactions. The three-dimensional structure of the enzyme was recently determined from two different sources: at 2.5-3.0 A resolution for DAAO from pig kidney and at 1.2-1.8 A resolution for R. gracilis. The active site can be clearly depicted: the striking absence of essential residues acting in acid-base catalysis and the mode of substrate orientation into the active site, taken together with the results of free-energy correlation studies, clearly support a hydrid transfer type of mechanism in which the orbital steering between the substrate and the isoalloxazine atoms plays a crucial role during catalysis. PMID:11130179

Pilone, M S

2000-11-01

418

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

419

Multidomain flavin-dependent sulfhydryl oxidases.  

PubMed

Eukaryotic flavin-dependent sulfhydryl oxidases catalyze oxidative protein folding with the generation of disulfides and the reduction of oxygen to hydrogen peroxide. This review deals principally with the Quiescinsulfhydryl oxidases (QSOX) that are found in multiple forms in multicellular organisms and singly in a number of protozoan parasites. QSOX is an ancient fusion of thioredoxin domains and an FAD-binding module, ERV1/ALR. Interdomain disulfide exchanges transmit reducing equivalents from substrates to the flavin cofactor and thence to molecular oxygen. The in vitro substrate specificity of avian QSOX1 and the likely substrates of QSOXs in vivo are discussed. The location of QSOX immunoreactivity and mRNA expression levels in human cells and tissues is reviewed. Generally, there is a marked association of QSOX1 expression with cell types that have a high secretory load of disulfide-containing peptides and proteins. The abundance of sulfhydryl oxidases in the islets of Langerhans suggests that oxidative protein folding may directly contribute to the oxidative stress believed to be a factor in the progression to type II diabetes. Finally, the structure and mechanism of QSOX proteins is compared to their smaller stand-alone cousins: yeast ERV1p and ERV2p, the mammalian augmenter of liver regeneration (ALR), and the viral ALR homologs. PMID:16677076

Coppock, Donald L; Thorpe, Colin

2006-01-01

420

Amperometric detection of catechol using tyrosinase modified electrodes enhanced by the layer-by-layer assembly of gold nanocubes and polyelectrolytes.  

PubMed

A novel amperometric biosensor for catechol was developed using the layer-by-layer (LbL) self-assembly of positively charged hexadecyltrimethylammonium stabilized gold nanocubes (AuNCs), negatively charged poly(sodium 4-styrenesulfonate) and tyrosinase on a screen printed carbon electrode (SPCE). A carboxylic acid terminated alkanethiol assembled on electrochemically deposited Au nanoparticles on a SPCE was used as a platform for LbL assembly. Each SPCE sensor surface was terminated with tyrosinase and the electrocatalytic response due to the tyrosinase reaction with catechol was measured using cyclic voltammetry and square wave voltammetry (SWV). The effect of introducing AuNCs into the LbL assembly to further enhance the catechol detection performance was then investigated by comparing the SWV results to those from biosensors created using both the tyrosinase modified LbL assembly in the absence of