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1

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

2

Linkage between Catecholate Siderophores and the Multicopper Oxidase CueO in Escherichia coli  

Microsoft Academic Search

The multicopper oxidase CueO had previously been demonstrated to exhibit phenoloxidase activity and was implicated in intrinsic copper resistance in Escherichia coli. Catecholates can potentially reduce Cu(II) to the prooxidant Cu(I). In this report we provide evidence that CueO protects E. coli cells by oxidizing enterobactin, the catechol iron siderophore of E. coli, in the presence of copper. In vitro,

Gregor Grass; Keshari Thakali; Phillip E. Klebba; Daniel Thieme; Axel Muller; Gunter F. Wildner; Christopher Rensing

2004-01-01

3

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

Microsoft Academic Search

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

Justin Kemmegne Mbouguen; Emmanuel Ngameni; Alain Walcarius

2007-01-01

4

Enzymatic dynamics of catechol oxidase from Gastrolina depressa  

Microsoft Academic Search

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

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

2010-01-01

5

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

6

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

PubMed

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 k(cat)/K(m) ratio for conjugated bilirubin (1,513 mM?ą s?ą) is higher than that obtained for the BOD from M. verrucaria expressed in native fungus (980 mM?ą s?ą), with the lowest K(m) measured for any BOD highly desirable for detection of bilirubin in medical samples. In addition, this protein exhibits a half-life for deactivation >300 min at 37 °C, high stability at pH 7, and high tolerance towards urea, making it an ideal candidate for the elaboration of biofuel cells, powering implantable medical devices. Finally, this new BOD is efficient in decolorizing textile dyes such as Remazol brilliant Blue R, making it useful for environmentally friendly industrial applications. PMID:22350257

Durand, Fabien; Gounel, Sébastien; Kjaergaard, Christian H; Solomon, Edward I; Mano, Nicolas

2012-12-01

7

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

PubMed

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

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

2015-02-10

8

Ligand centered radical pathway in catechol oxidase activity with a trinuclear zinc-based model: Synthesis, structural characterization and luminescence properties.  

PubMed

A new trinuclear zinc(II) complex, [Zn3(L)(NCS)2](NO3)2·CH3OH·H2O (1), of a (N,O)-donor compartmental Schiff base ligand (H2L=N,N'-bis(3-methoxysalicylidene)-1,3-diamino-2-propanol), has been synthesized in crystalline phase. The zinc(II) complex has been characterized by elemental analysis, IR spectroscopy, UV-Vis spectroscopy, powder X-ray diffraction study (PXRD), (1)H NMR, EI mass spectrometry and thermogravimetric analysis. PXRD revealed that 1 crystallizes in P-1 space group with a=9.218Ĺ, b=10.849Ĺ, c=18.339Ĺ, with unit cell volume is 2179.713(Ĺ)(3). Fluorescence spectra in methanolic solution reflect that intensity of emission for 1 is much higher compared to H2L and both the compounds exhibit good fluorescence properties. The complex 1 exhibits significant catalytic activities of biological relevance, viz. catechol oxidase. In methanol, it efficiently catalyzes the oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) to corresponding quinone via formation of a dinuclear species as [Zn2(L)(3,5-DTBC)]. Electron Paramagnetic Resonance (EPR) experiment suggests generation of radicals in the presence of 3,5-DTBC and it may be proposed that the radical pathway is probably responsible for conversion of 3,5-DTBC to 3,5-DTBQ promoted by complex of redox-innocent Zn(II) ion. PMID:25754390

Pal, Sukanta; Chowdhury, Biswajit; Patra, Moumita; Maji, Milan; Biswas, Bhaskar

2015-06-01

9

Gonadectomy and hormone replacement exert region- and enzyme isoform-specific effects on monoamine oxidase and catechol-O-methyltransferase activity in prefrontal cortex and neostriatum of adult male rats.  

PubMed

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

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

2010-02-01

10

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

PubMed Central

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

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

2010-01-01

11

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

PubMed

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

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

1998-02-01

12

Molecular Structure of Catechol  

NSDL National Science Digital Library

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

2004-11-09

13

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

PubMed

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

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

2014-01-01

14

Polyphenol Oxidase Activity Expression in Ralstonia solanacearum  

Microsoft Academic Search

Sequencing of the genome of Ralstonia solanacearum revealed several genes that putatively code for poly- phenol oxidases (PPOs). To study the actual expression of these genes, we looked for and detected all kinds of PPO activities, including laccase, cresolase, and catechol oxidase activities, in cellular extracts of this micro- organism. The conditions for the PPO assays were optimized for the

Diana Hernandez-Romero; Francisco Solano; Antonio Sanchez-Amat

2005-01-01

15

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

PubMed

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

Jacobsohn, G M; Jacobsohn, M K

1984-07-01

16

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

PubMed

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

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

2013-07-01

17

Acetone extracted propolis as a novel membrane and its application in phenol biosensors: the case of catechol  

Microsoft Academic Search

A novel biosensor for catechol has been constructed by immobilizing polyphenol oxidase (PPO) into acetone-extracted propolis\\u000a (AEP) composite modified with gold nanoparticles (GNPs) and attached to multiwalled carbon nanotube (MWCNTs) on a gold electrode\\u000a surface. The propolis for AEP was obtained from honeybee colonies. Under the optimum conditions, this method could be successfully\\u000a used for the amperometric determination of catechol

Farshad Kheiri; Reza Emamali Sabzi; Elham Jannatdoust; Hassan Sedghi

18

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

Microsoft Academic Search

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

Serap Dogan; Mehmet Dogan

2004-01-01

19

Beyond brown: polyphenol oxidases as enzymes of plant specialized metabolism  

PubMed Central

Most cloned and/or characterized plant polyphenol oxidases (PPOs) have catechol oxidase activity (i.e., they oxidize o-diphenols to o-quinones) and are localized or predicted to be localized to plastids. As a class, they have broad substrate specificity and are associated with browning of produce and other plant materials. Because PPOs are often induced by wounding or pathogen attack, they are most generally believed to play important roles in plant defense responses. However, a few well-characterized PPOs appear to have very specific roles in the biosynthesis of specialized metabolites via both tyrosinase (monophenol oxidase) and catechol oxidase activities. Here we detail a few examples of these and explore the possibility that there may be many more “biosynthetic” PPOs. PMID:25642234

Sullivan, Michael L.

2015-01-01

20

POLYPHENOL OXIDASE ACTIVITY IN BANANA CHIPS DURING OSMOTIC DEHYDRATION  

Microsoft Academic Search

Various treatments were used to determine polyphenol oxidase activity changes during osmotic dehydration of banana slices. A temperature of 35 °C and 5.0 pH were used as the most adequate conditions for polyphenol oxidase activity determination when 4-methyl catechol was used as a substrate. Enzyme activity change was determined in the central and edge region of fruit. The central part

K. N. Waliszewski; R. H. Garcia; M. Ramirez; M. A. Garcia

2000-01-01

21

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

22

Oxidative calcium release from catechol.  

PubMed

Oxidation of 4-methylcatechol previously exposed to aqueous calcium chloride was shown by ion chromatography to be associated with release of calcium ions. The catechol was oxidised to the corresponding orthoquinone by the use of tyrosinase from Agaricus bisporus. The oxidative release of calcium from the catechol is ascribed to the diminution of the available hydroxyl functions able to act as chelating groups. Our results suggest that the redox status of melanin may regulate calcium binding and influence calcium levels in pigmented cells. PMID:25740160

Riley, Patrick A; Stratford, Michael R L

2015-04-01

23

Development of a potentiometric catechol biosensor by entrapment of tyrosinase within polypyrrole film  

Microsoft Academic Search

A method is described for the construction of a potentiometric catechol biosensor by entrapment of tyrosinase (polyphenol oxidase; PPO) into a conducting polypyrrole film on a platinum electrode. The optimum conditions for the formation of the PPy–Tyr (polypyrrole–tyrosinase) film include a current density of 0.5mAcm?2, a polymerization period of 150s, 0.1M pyrrole and 50UmL?1 tyrosinase. The presence of tyrosinase in

Qaisar Ameer; Samuel B. Adeloju

2009-01-01

24

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

25

Some Biochemical Properties of Polyphenol Oxidase from Celery  

Microsoft Academic Search

Polyphenol oxidase (PPO, EC 1.14.18.1) was extracted from celery roots (Apium graveolens L.) with 0.1 M phosphate buffer, pH 7.0. The PPO was partially purified by (NH4)2SO4 and dialysis. Substrate specificity experiments were carried out with catechol, pyrogallol, L?DOPA, p?cresol, resorcinol, and tyrosine. The Km for pyrogallol, catechol, and L?DOPA were 4.5, 8.3, and 6.2 mM, respectively, at 25°C. Data for Vmax\\/Km

2004-01-01

26

Dual oxidases  

PubMed Central

Reactive oxygen species (ROS) have an important role in various physiological processes including host defence, mitogenesis, hormone biosynthesis, apoptosis and fertilization. Currently, the most characterized ROS-producing system operates in phagocytic cells, where ROS generated during phagocytosis act in host defence. Recently, several novel homologues of the phagocytic oxidase have been discovered and this protein family is now designated as the NOX/DUOX family of NADPH oxidases. NOX/DUOX enzymes function in a variety of tissues, including colon, kidney, thyroid gland, testis, salivary glands, airways and lymphoid organs. Importantly, members of the enzyme family are also found in non-mammalian species, including Caenorhabditis elegans and sea urchin. The physiological functions of novel NADPH oxidase enzymes are currently largely unknown. This review focuses on our current knowledge about dual oxidases. PMID:16321800

Donkó, Ágnes; Péterfi, Zalán; Sum, Adrienn; Leto, Thomas; Geiszt, Miklós

2005-01-01

27

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

Microsoft Academic Search

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

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

2007-01-01

28

Spectroscopic Studies of the Catechol Dioxygenases.  

ERIC Educational Resources Information Center

The catechol dioxygenases are bacterial iron-containing enzymes that catalyze the oxidative cleavage of catechols. These enzymes serve as a component of nature's mechanisms for degrading aromatic compounds in the environment. The structure and mechanistic aspects of these enzymes are described. (JN)

Que, Lawrence Jr.

1985-01-01

29

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

30

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

Microsoft Academic Search

A strain of Pseudomonas fluorescens was capable of co-metabolizing 3-chlorobenzoic acid with the production of a chlorinated catechol black pigment. A peroxidase and another enzymatic activity referred to as a polyphenol oxidase were found to be involved in the oxidation of 4-chlorocatechol to 4-chloro-1,2-benzoquinone, i.e. in the production of highly reactive substrates for pigment formation. Therefore, P. fluorescens cells were

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

1993-01-01

31

Purification and some properties of polyphenol oxidase of longan fruit  

Microsoft Academic Search

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

Yue-Ming Jiang

1999-01-01

32

Purification and characterization of polyphenol oxidase from Ferula sp  

Microsoft Academic Search

Polyphenol oxidase (PPO) of several Ferula sp. was extracted and purified through (NH4)2SO4 precipitation, dialysis, and gel filtration chromatography. Leaf and stem extracts were used for the determination of enzyme properties. Optimum conditions, for pH, temperature, and ionic strength were determined. The best substrates of PPO were catechol for leaf and (?) epicatechin for stem samples. Optimum pH and temperature

Mustafa Erat; Halis Sakiroglu; O. Irfan Kufrevioglu

2006-01-01

33

Polyphenol oxidase activity of oregano at different stages  

Microsoft Academic Search

The effects of pH and temperature on polyphenol oxidase (PPO) activity of organs such as root, stem and leaf, of Origanum vulgare ssp. hirtum, collected at different stages (vegetative and generative) and from various localities around Balikesir, Turkey, were investigated using catechol as a substrate. PPO obtained from organs of Origanum was partially purified by (NH4)2SO4 precipitation, followed by dialysis.

Serap Do?an; Oktay Arslan; Faz?l Özen

2005-01-01

34

Quantification and characterisation of polyphenol oxidase from vanilla bean  

Microsoft Academic Search

Polyphenol oxidase (PPO) of Vanilla planifolia Andrews beans was extracted and purified through ammonium sulphate precipitation, dialysis, and gel filtration chromatography. PPO activity was measured by improved UV technique using 4-methylcatechol and catechol as substrates increasing substantial sensitivity of previous procedure. The optimum pH and temperature for PPO activity were found to be 3.0 and 3.4 and 37°C, respectively. Km

Krzysztof N. Waliszewski; Ofelia Márquez; Violeta T. Pardio

2009-01-01

35

volution de la sensibilit des glumelles du riz Pyricularia oryzae Cav. et Drechslera oryzae (Br.  

E-print Network

Évolution de la sensibilité des glumelles du riz ŕ Pyricularia oryzae Cav. et ŕ Drechslera oryzae, Drechslera, Conservation. Susceptibility of rice glumes to Pyricularia oryzae Cav. and Drechslera oryzae (Br. INTRODUCTION Pyricularia oryzae Cav. et Drechslera oryzae (Br. de Haan) Sub. et Jain, parasites les plus

Paris-Sud XI, Université de

36

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

37

Genetic Diversity of Xanthomonas oryzae pv. oryzae in Asia  

PubMed Central

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 from X. oryzae pv. oryzae, IS1112, an insertion sequence, and avrXa10, a member of a family of avirulence genes, were used as probes to analyze the genomes of 308 strains of X. oryzae pv. oryzae collected from China, India, Indonesia, Korea, Malaysia, Nepal, and the Philippines. On the basis of the consensus of three clustering statistics, the collection formed five clusters. Genetic distances within the five clusters ranged from 0.16 to 0.51, and distances between clusters ranged from 0.48 to 0.64. Three of the five clusters consisted of strains from a single country. Strains within two clusters, however, were found in more than one country, suggesting patterns of movement of the pathogen. The pathotype of X. oryzae pv. oryzae was determined for 226 strains by inoculating five rice differential cultivars. More than one pathotype was associated with each cluster; however, some pathotypes were associated with only one cluster. Most strains from South Asia (Nepal and India) were virulent to cultivars containing the bacterial blight resistance gene xa-5, while most strains from other countries were avirulent to xa-5. The regional differentiation of clusters of X. oryzae pv. oryzae in Asia and the association of some pathotypes of X. oryzae pv. oryzae with single clusters suggested that strategies that target regional resistance breeding and gene deployment are feasible. PMID:16534980

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

1995-01-01

38

PEM Anchorage on Titanium Using Catechol Grafting  

PubMed Central

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

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

2012-01-01

39

Boronate derivatives of functionally diverse catechols: stability studies.  

PubMed

Benzeneboronate of catecholic carboxyl methyl esters, N-acetyldopamine, coumarin and catechol estrogens were prepared as crystalline derivatives in high yield. Related catechol compounds with extra polar functional group(s) (OH, NH2) do not form or only partially form unstable cyclic boronate derivatives. PMID:20428047

Ketuly, Kamal Aziz; Hadi, A Hamid A

2010-04-01

40

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

SciTech Connect

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

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

2013-12-15

41

Characterization of polyphenol oxidase from butter lettuce ( Lactuca sativa var. capitata L.)  

Microsoft Academic Search

Polyphenol oxidase (PPO) was isolated from butter lettuce (Lactuca sativa var. capitata L.) grown in Poland and its biochemical characteristic were studied. PPO from butter lettuce showed a higher affinity to 4-methylcatechol than to catechol. The KM and Vmax values were: 3.20±0.01mM and 4081±8U\\/mlmin?1 for catechol and 1.00±0.09mM and 5405±3U\\/mlmin?1 for 4-methylcatechol. The optimum pHs of the enzyme were found

Urszula Gawlik-Dziki; Urszula Z?otek; Micha? ?wieca

2008-01-01

42

Semiquinone anion radicals of catechol(amine)s, catechol estrogens, and their metal ion complexes.  

PubMed Central

The characterization and identification of semiquinone radicals from catechol(amine)s and catechol estrogens by electron spin resonance spectroscopy is addressed. The use of diamagnetic metal ions, especially Mg2+ and Zn2+ ions, to detect transient semiquinone radicals in biological systems and to monitor their reactions, is discussed. A brief account of the identification and reactions of quinones is also presented. PMID:3007089

Kalyanaraman, B; Felix, C C; Sealy, R C

1985-01-01

43

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

PubMed

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

Müller, Thomas

2015-02-01

44

Herbicidal potential of catechol as an allelochemical.  

PubMed

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

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

2006-01-01

45

Anomalous cage effect of the excited state dynamics of catechol in the 18-crown-6-catechol host-guest complex.  

PubMed

We determined the number of isomers and their structures for the 18-crown-6 (18C6)-catechol host-guest complex, and examined the effect of the complex formation on the S1 ((1)??*) dynamics of catechol under a supersonically cooled gas phase condition and in cyclohexane solution at room temperature. In the gas phase experiment, UV-UV hole-burning spectra of the 18C6-catechol 1:1 complex indicate that there are three stable isomers. For bare catechol, it has been reported that two adjacent OH groups have an intramolecular hydrogen (H) bond. The IR-UV double resonance spectra show two types of isomers in the 18C6-catechol 1:1 complex; one of the three 18C6-catechol 1:1 isomers has the intramolecular H-bond between the two OH groups, while in the other two isomers the intramolecular H-bond is broken and the two OH groups are H-bonded to oxygen atoms of 18C6. The complex formation with 18C6 substantially elongates the S1 lifetime from 7 ps for bare catechol and 2.0 ns for the catechol-H2O complex to 10.3 ns for the 18C6-catechol 1:1 complex. Density functional theory calculations of the 18C6-catechol 1:1 complex suggest that this elongation is attributed to a larger energy gap between the S1 ((1)??*) and (1)??* states than that of bare catechol or the catechol-H2O complex. In cyclohexane solution, the enhancement of the fluorescence intensity of catechol was found by adding 18C6, due to the formation of the 18C6-catechol complex in solution, and the complex has a longer S1 lifetime than that of catechol monomer. From the concentration dependence of the fluorescence intensity, we estimated the equilibrium constant K for the 18C6 + catechol ? 18C6-catechol reaction. The obtained value (log K = 2.3) in cyclohexane is comparable to those for alkali metal ions or other molecular ions, indicating that 18C6 efficiently captures catechol in solution. Therefore, 18C6 can be used as a sensitive sensor of catechol derivatives in solution with its high ability of fluorescence enhancement. PMID:25350575

Morishima, Fumiya; Kusaka, Ryoji; Inokuchi, Yoshiya; Haino, Takeharu; Ebata, Takayuki

2015-02-12

46

Rice ( Oryza) hemoglobins  

PubMed Central

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

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

2014-01-01

47

Toxicity of catechol to alternaria spp  

Microsoft Academic Search

In slide-germination tests concentration of 50 p.p.m. or more of catechol were inhibitory to spore germination ofAlternaria tomato, A. solani, A. melongenae, A. longipes, A. brassicicola. A. brassicae, A. raphani, A. triticina and anAlternaria sp. isolated from onion. More than 70 % inhibition of conidial germination was caused by 100 p.p.m. of the compound. Nearly complete or complete inhibition occurred

R. S. Singh; H. S. Chaube

1971-01-01

48

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

Microsoft Academic Search

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

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

2010-01-01

49

Purification and Biochemical Characterization of Polyphenol Oxidases from Embryogenic and Nonembryogenic Cotton ( Gossypium hirsutum L.) Cells  

Microsoft Academic Search

Polyphenol oxidases (PPOs) were isolated from cell suspensions of two cultivars of cotton (Gossypium hirsutum L.), and their biochemical characteristics were studied. PPO from Coker 312, an embryogenic cultivar, showed a highest affinity\\u000a to catechol 20 mM, and PPO from R405-2000, a nonembryogenic cultivar, showed a highest affinity to 4-methylcatechol 20 mM.\\u000a The optimal pH for PPO activity was 7.0 and 6.0

Tanoh Hilaire Kouakou; Yatty Justin Kouadio; Patrice Kouamé; Pierre Waffo-Téguo; Alain Décendit; Jean-Michel Mérillon

2009-01-01

50

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

Microsoft Academic Search

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

Jiang Yue-Ming; Giora Zauberman; Yoram Fuchs

1997-01-01

51

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

Microsoft Academic Search

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

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

2006-01-01

52

Decolorization of the Textile Dyes Using Purified Banana Pulp Polyphenol Oxidase  

Microsoft Academic Search

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

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

2011-01-01

53

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

54

An optical MEMS sensor utilizing a chitosan film for catechol detection  

Microsoft Academic Search

Catechol is a widely studied phenol that is a common byproduct of factory waste. The presence of catechol in drinking water and food poses a safety concern due to its toxic and possibly carcinogenic effects. We report the successful fabrication and testing of an optical MEMS sensor for the detection of catechol. Studies on catechol detection have shown that byproducts

Peter Dykstra; Junjie Hao; Stephan T. Koev; Gregory F. Payne; Liangli Yu; Reza Ghodssi

2009-01-01

55

Amperometric biosensor for catechol using electrochemical template process  

Microsoft Academic Search

A novel amperometric biosensor for the determination of catechol was developed accordingly to the electrochemical template procedure. The optimum fabricating conditions of the biosensor were studied. The resulting biosensor with the limit of less than 0.05?M can be used for detection of catechol in the linear range of 2.5–140?M. The maximum response current (Imax) and the Michaelis–Menten constant (k?m) are

Yongyan Tan; Jinqing Kan; Shengqi Li

2011-01-01

56

Selective methylation of catechol: catalyst development and characterisation  

Microsoft Academic Search

Gas-phase methylation of catechol by methanol was studied on ?-Al2O3 modified by the basic elements: K, Li, Mg and Ca. Addition of 7.5 at.% Mg to ?-Al2O3 was optimal and increased the 3-methyl catechol selectivity from 0.26 to 0.65. X-ray diffraction experiments showed the diffusion of Li+ and Mg2+ cations into the ?-Al2O3 bulk. This induces a change in the

L. Kiwi-Minsker; S. Porchet; P. Moeckli; R. Doepper; A. Renken

1996-01-01

57

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

Microsoft Academic Search

Cytochrome P-450 and the electron-donor, NADPH-cytochrome c reductase were isolated from phenobarbital induced rat liver microsomes. Both benzene and its primary metabolite phenol, were substrates for the reconstituted purified phenobarbital induced rat liver mixed function oxidase system. Benzene was metabolized to phenol and the polyhydroxylated metabolites; catechol, hydroquinone and 1,2,4 benzenetriol. Benzene elicited a Type I spectral change upon its

1986-01-01

58

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

Microsoft Academic Search

Scytalidium thermophilum produces an extracellular phenol oxidase on glucose-containing medium. Certain phenolic acids, specifically gallic acid and tannic acid, induce the expression of the enzyme. Production at 45°C in batch cultures is growth-associated and is enhanced in the presence of 160 ?M CuSO4.5 H2O and 3 mM gallic acid. The highest enzyme activity is observed at pH 7.5 and 65°C, on catechol. When

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

2006-01-01

59

Cholesterol oxidase: physiological functions  

PubMed Central

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

Kreit, Joseph; Sampson, Nicole S.

2009-01-01

60

Genetic diversity and species relationships in the Oryza complex and glufosinate tolerance in rice  

E-print Network

rufipogon, Oryza nivara and Oryza sativa ssp. indica samples...................... 70 3-6. SINE and MITE data for annual and perennial Oryza species................... 72 3-7. Multi-dimensional scaling (MDS) of SINE and MITE data for Oryza...-9. Phylogenetic tree of microsatellite data for Oryza sativa ssp. japonica, Oryza sativa ssp. indica, NSGC Oryza rufipogon and Oryza nivara, red rice and perennial Oryza rufipogon samples from the GS/MDS (Figure 3-4) and STRUCTURE (Figure 3-5) analysis...

Vaughan, Laura Kelly

2005-08-29

61

Polyphenol oxidase from yacon roots (Smallanthus sonchifolius).  

PubMed

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

Neves, Valdir Augusto; da Silva, Maraiza Aparecida

2007-03-21

62

Isomer specific syntheses of chlorinated catechols and guaiacols relevant to pulp bleaching.  

PubMed

A variety of chlorinated catechols and guaiacols relevant to pulp bleaching were synthesized by employing fundamental differences in the acidities of phenolic hydroxyl groups in chlorinated catechols, and directive effects in guaiacols. PMID:11592414

McKague, A B; Taylor, D R

2001-10-01

63

Evaluation of Mut(S) and Mut (+) Pichia pastoris Strains for Membrane-Bound Catechol-O-Methyltransferase Biosynthesis.  

PubMed

Catechol-O-methyltransferase (COMT, EC 2.1.1.6) is an enzyme that catalyzes the methylation of catechol substrates, and while structural and functional studies of its membrane-bound isoform (MBCOMT) are still hampered by low recombinant production, Pichia pastoris has been described as an attractive host for the production of correctly folded and inserted membrane proteins. Hence, in this work, MBCOMT biosynthesis was developed using P. pastoris X33 and KM71H cells in shake flasks containing a semidefined medium with different methanol concentrations. Moreover, after P. pastoris glass beads lysis, biologically and immunologically active hMBCOMT was found mainly in the solubilized membrane fraction whose kinetic parameters were identical to its correspondent native enzyme. In addition, mixed feeds of methanol and glycerol or sorbitol were also employed, and its levels quantified using liquid chromatography coupled to refractive index detection. Overall, for the first time, two P. pastoris strains with opposite phenotypes were applied for MBCOMT biosynthesis under the control of the strongly methanol-inducible alcohol oxidase (AOX) promoter. Moreover, this eukaryotic system seems to be a promising approach to deliver MBCOMT in high quantities from fermentor cultures with a lower cost-benefit due to the cheaper cultivation media coupled with the higher titers tipically achieved in biorreactors, when compared with previously reported mammallian cell cultures. PMID:25712908

Pedro, A Q; Oppolzer, D; Bonifácio, M J; Maia, C J; Queiroz, J A; Passarinha, L A

2015-04-01

64

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

PubMed Central

Background Xanthomonas oryzae pv. oryzae, the causal agent of bacterial blight disease, is a serious pathogen of rice. Here we describe a fluorescent marker system to study virulence and pathogenicity of X. oryzae pv. oryzae. Results A fluorescent X. oryzae pv. oryzae Philippine race 6 strain expressing green fluorescent protein (GFP) (PXO99GFP) was generated using the gfp gene under the control of the neomycin promoter in the vector, pPneo-gfp. The PXO99GFPstrain displayed identical virulence and avirulence properties as the wild type control strain, PXO99. Using fluorescent microscopy, bacterial multiplication and colonization were directly observed in rice xylem vessels. Accurate and rapid determination of bacterial growth was assessed using fluoremetry and an Enzyme-Linked ImmunoSorbant Assay (ELISA). Conclusion Our results indicate that the fluorescent marker system is useful for assessing bacterial infection and monitoring bacterial multiplication in planta. PMID:18826644

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

2008-01-01

65

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

66

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

67

Reactive oxygen species production by catechol stabilized copper nanoparticles  

NASA Astrophysics Data System (ADS)

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

Chen, Cheng; Ahmed, Ishtiaq; Fruk, Ljiljana

2013-11-01

68

Distribution of the related weevil species Sitophilus oryzae and S. zeamais in Brazil.  

PubMed

The genus Sitophilus (Coleoptera: Curculionidae) encompasses species of great economic importance as stored grain pests worldwide. Among these species, the maize and the rice weevils (Sitophilus zeamais and Sitophilus oryzae, respectively) are particularly important in warmer climates. These two weevils exhibit closely morphological and ecological resemblance making difficult their proper identification and recognition of their distribution in grain-producing regions. Both species are recorded in South America and particularly in Brazil, but their respective distribution and prevalence were not yet assessed in the region. Therefore, several insect samples throughout Brazil were collected and subjected to morphological identification using male genitalia and also using molecular identification with species-specific primers designed for clear recognition of both the species. The primers were designed for the specific amplification of a gene fragment of the cytochrome oxidase subunit I, which exhibited high specificity during our preliminary experiments with insects from six populations of known species (either S. zeamais or S. oryzae). Both identification strategies provided the same results indicating prevalence of the maize weevil S. zeamais throughout the country. Two hypotheses may explain such prevalence: (i) the likely host preference of S. zeamais for maize because this is the most cultivated cereal in Brazil, and (ii) the prevalence of S. zeamais in tropical regions as compared with S. oryzae, which is more disseminated in subtropical and temperate regions. PMID:23956213

Corręa, Alberto S; Orlando de Oliveira, Luiz; Braga, Lucas S; Guedes, Raul Narciso C

2013-12-01

69

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

Microsoft Academic Search

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

Jian Shao; Huimin Ge; Yumin Yang

2007-01-01

70

Selected Kinetic Properties of Polyphenol Oxidase Extracted from Rosmarinus Officinalis L  

Microsoft Academic Search

Polyphenol oxidase from Rosmarinus officinalis L. (PPO, EC 1:14:18.1) was extracted and partially purified by using (NH4)2SO4 precipitation and dialysis. Stable and highly active PPO extracts were obtained using 0.5% (w\\/v) PEG and 0.5% (w\\/v) Triton X-100 in 0.1 M phosphate buffer 7.0. KM values were found to be as 14.3 mM for catechol. Four isoenzymes of Rosemary PPO were

Tulin Aydemir

2010-01-01

71

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

72

Crystallization of carbohydrate oxidase from Microdochium nivale  

PubMed Central

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

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

2009-01-01

73

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

74

Iron-Binding Catechols and Virulence in Escherichia coli  

PubMed Central

Previous work suggested that virulent bacteria, which can grow rapidly in serum, must possess a specific mechanism for removing iron from its transferrin complex. Two strains of Escherichia coli were examined with this in mind. Strain O141, which showed inoculum-dependent growth in serum and multiplied in the mouse peritoneum, secreted iron-binding catechols into both synthetic medium and serum. One of these compounds has an association constant for iron similar to that of transferrin. Both transferrin and ethylenediamine-di-o-hydroxyphenyl acetic acid (EDDA), which have very high affinities for ferric iron, induced catechol synthesis in growing cultures of strain O111. This organism was inhibited by normal horse serum. Further work showed that traces of specific antibody inhibited catechol synthesis by O111 exposed to EDDA; therefore, the existence of this inhibitory process means that the organism can no longer obtain Fe3+, which all remains bound to transferrin in serum. In vivo, the inhibition of O111 is similar to that produced by serum in vitro. Neither phagocytosis nor killing by complement appeared to be of any significance during the first 4 h of the infections. Significantly, the purified catechol was capable of abolishing bacteriostasis in vivo. Since these results show that the production of iron-binding catechols is essential for rapid bacterial growth both in vitro and in vivo, these compounds should therefore be considered as true virulence factors. Conversely, any interference by the host with the production or activity of these compounds would constitute an important aspect of antibacterial defense. Images PMID:16558077

Rogers, Henry J.

1973-01-01

75

NADPH oxidases and cancer.  

PubMed

The mechanism by which reactive oxygen species (ROS) are produced by tumour cells remained incompletely understood until the discovery over the last 15 years of the family of NADPH oxidases (NOXs 1-5 and dual oxidases DUOX1/2) which are structural homologues of gp91phox, the major membrane-bound component of the respiratory burst oxidase of leucocytes. Knowledge of the roles of the NOX isoforms in cancer is rapidly expanding. Recent evidence suggests that both NOX1 and DUOX2 species produce ROS in the gastrointestinal tract as a result of chronic inflammatory stress; cytokine induction (by interferon-?, tumour necrosis factor ?, and interleukins IL-4 and IL-13) of NOX1 and DUOX2 may contribute to the development of colorectal and pancreatic carcinomas in patients with inflammatory bowel disease and chronic pancreatitis, respectively. NOX4 expression is increased in pre-malignant fibrotic states which may lead to carcinomas of the lung and liver. NOX5 is highly expressed in malignant melanomas, prostate cancer and Barrett's oesophagus-associated adenocarcinomas, and in the last it is related to chronic gastro-oesophageal reflux and inflammation. Over-expression of functional NOX proteins in many tissues helps to explain tissue injury and DNA damage from ROS that accompany pre-malignant conditions, as well as elucidating the potential mechanisms of NOX-related damage that contribute to both the initiation and the progression of a wide range of solid and haematopoietic malignancies. PMID:25818486

Roy, Krishnendu; Wu, Yongzhong; Meitzler, Jennifer L; Juhasz, Agnes; Liu, Han; Jiang, Guojian; Lu, Jiamo; Antony, Smitha; Doroshow, James H

2015-06-01

76

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

NASA Astrophysics Data System (ADS)

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

Konschin, Henrik; Tylli, Henrik

1982-11-01

77

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

NASA Astrophysics Data System (ADS)

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

Konschin, Henrik; Tylli, Henrik

78

Purification and structural analysis of membrane-bound polyphenol oxidase from Fuji apple.  

PubMed

Membrane-bound polyphenol oxidase (mPPO) in Fuji apple (Malus domestica Borkh. cv. Red Fuji) was purified and analyzed with a nanoelectrospray ionization mass spectrometer. The three-dimensional model and binding site of mPPO to 4-methyl catechol were also studied using molecular docking. mPPO was purified 54.41-fold using temperature-induced phase partitioning technique and ion exchange chromatography. mPPO had a molecular weight of 67.3kDa. Even though a significant level of homology was observed between mPPO and the soluble polyphenol oxidase in the copper binding sequence, there was another region, rich in histidine residues, which differed in 13 amino acids. The three-dimensional structure of mPPO consisted of six ?-helices, two short ?-strands, and ten random coils. The putative substrate-binding pocket contained six polar or charged amino acids, His191, His221, Trp224, Trp228, Phe227, and Val190. Trp224 and Trp228 formed hydrogen bonds with 4-methyl-catechol. PMID:25863612

Liu, Fang; Zhao, Jin-Hong; Wen, Xin; Ni, Yuan-Ying

2015-09-15

79

A catechol biosensor based on electrospun carbon nanofibers  

PubMed Central

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

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

2014-01-01

80

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

81

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

82

High-resolution analysis of catechol-type siderophores using polyamide thin layer chromatography  

Microsoft Academic Search

The iron-deficient culture supernatant of a soil bacterial strain identified as Erwinia sp. was analyzed using a new high-resolution polyamide thin layer chromatography (TLC) and a silica TLC. The results showed both TLC methods were very effective for separating simple catechol compounds such as 2,3-dihydroxybenzoic acid (2,3-DHBA) and catechol. However, in the analysis of more complicated catechol compounds or true

Xiaojun Xie; Jingguo Wang; Hongli Yuan

2006-01-01

83

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

84

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

Microsoft Academic Search

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

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

2010-01-01

85

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

Microsoft Academic Search

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

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

2007-01-01

86

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

Microsoft Academic Search

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

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

2011-01-01

87

Transposable element distribution, abundance and role in genome size variation in the genus Oryza  

Microsoft Academic Search

BACKGROUND: The genus Oryza is composed of 10 distinct genome types, 6 diploid and 4 polyploid, and includes the world's most important food crop – rice (Oryza sativa [AA]). Genome size variation in the Oryza is more than 3-fold and ranges from 357 Mbp in Oryza glaberrima [AA] to 1283 Mbp in the polyploid Oryza ridleyi [HHJJ]. Because repetitive elements

Andrea Zuccolo; Aswathy Sebastian; Jayson Talag; Yeisoo Yu; HyeRan Kim; Kristi Collura; Dave Kudrna; Rod A Wing

2007-01-01

88

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

PubMed Central

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

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

2008-01-01

89

A sensitive and selective spectrophotometric estimation of catechol derivatives in pharmaceutical preparations  

Microsoft Academic Search

A sensitive and simple spectrophotometric method for the estimation of catechol and its derivatives like dopamine hydrochloride (DPH), levodopa (LDP), methyldopa (MDP) and adrenaline hydrochloride (ADH) in both pure form and in pharmaceutical formulation, is described. The method is based on the interaction of diazotised sulphanilamide (DSA) with catechol derivatives in the presence of molybdate ions in acidic medium. Absorbance

P. Nagaraja; R. A. Vasantha; K. R. Sunitha

2001-01-01

90

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

E-print Network

Urinary excretion of phenol, catechol, hydroquinone, and muconic acid by workers occupationally. The benzene urinary metabolites phenol, catechol, hydroqui- none, and muconic acid were measured of benzene air. For the subgroup of workers (n=27) with urinary phenol >50 ng/g creatinine (above which

California at Berkeley, University of

91

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

ERIC Educational Resources Information Center

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

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

2007-01-01

92

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

E-print Network

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

93

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

Microsoft Academic Search

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

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

1993-01-01

94

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

95

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

96

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

PubMed Central

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

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

2014-01-01

97

Spermine oxidase: ten years after  

Microsoft Academic Search

Spermine oxidase (SMO) was discovered much more recently than other enzymes involved in polyamine metabolism; this review\\u000a summarizes 10 years of researches on this enzyme. Spermine oxidase (SMO) is a FAD-dependent enzyme that specifically oxidizes\\u000a spermine (Spm) and plays a dominant role in the highly regulated mammalian polyamines catabolism. SMO participates in drug\\u000a response, apoptosis, response to stressful stimuli and etiology

Manuela Cervelli; Roberto Amendola; Fabio Polticelli; Paolo Mariottini

98

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

PubMed

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

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

2000-01-01

99

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. PMID:21622560

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

2011-01-01

100

Purification and characterization of polyphenol oxidase from fresh ginseng  

PubMed Central

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

Kim, Jae-Joon; Kim, Woo-Yeon

2013-01-01

101

Characterization of polyphenol oxidase activity in Ataulfo mango.  

PubMed

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

Cheema, Summervir; Sommerhalter, Monika

2015-03-15

102

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

103

Phylogeography of Asian wild rice, Oryza rufipogon, reveals multiple independent domestications of cultivated rice, Oryza sativa  

PubMed Central

Cultivated rice, Oryza sativa L., represents the world’s most important staple food crop, feeding more than half of the human population. Despite this essential role in world agriculture, the history of cultivated rice’s domestication from its wild ancestor, Oryza rufipogon, remains unclear. In this study, DNA sequence variation in three gene regions is examined in a phylogeographic approach to investigate the domestication of cultivated rice. Results indicate that India and Indochina may represent the ancestral center of diversity for O. rufipogon. Additionally, the data suggest that cultivated rice was domesticated at least twice from different O. rufipogon populations and that the products of these two independent domestication events are the two major rice varieties, Oryza sativa indica and Oryza sativa japonica. Based on this geographical analysis, O. sativa indica was domesticated within a region south of the Himalaya mountain range, likely eastern India, Myanmar, and Thailand, whereas O. sativa japonica was domesticated from wild rice in southern China. PMID:16766658

Londo, Jason P.; Chiang, Yu-Chung; Hung, Kuo-Hsiang; Chiang, Tzen-Yuh; Schaal, Barbara A.

2006-01-01

104

Study and characterization of polyphenol oxidase from eggplant (Solanum melongena L.).  

PubMed

In this study the catecholase and cresolase activities of eggplant polyphenol oxidase (PPO) were investigated. Enzyme activity was determined by measuring the increase in absorbance using catechol as substrate and 3-methyl-2-benzothiazolinone hydrazone (MBTH) as coupled reagent. The effects of substrate specificity, heat inactivation, temperature, pH, and inhibitors were investigated to understand the enzymatic alteration of ready-to-eat preparations. Browning of vegetables was determined through a colorimeter. Decrease of lightness (L*) and increase of color difference values (?E*) were correlated with tissue browning. Antibrowning agents were tested on PPO under the same conditions. The enzyme activity was strongly inhibited by 0.4 M citric acid. Under natural pH conditions, the enzyme was also inhibited by tartaric acid and acetic acid. All of the results were used to understand the best conditions for food transformation (ready-to-eat and grilled eggplant slices). PMID:21942648

Todaro, Aldo; Cavallaro, Rosalinda; Argento, Sergio; Branca, Ferdinando; Spagna, Giovanni

2011-10-26

105

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

PubMed

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

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

2011-01-01

106

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

107

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

108

QTL mapping and introgression of yield-related traits from Oryza glumaepatula to cultivated rice ( Oryza sativa ) using microsatellite markers  

Microsoft Academic Search

Rice (Oryza sativa) cultivar development currently faces the task of overcoming yield plateaus, which is difficult due to the narrow genetic base of breeding programs. Oryza glumaepatula is a diploid wild relative of cultivated rice, native to Central and South America, and is therefore a potential source of alleles of agronomic importance to rice breeding programs. We studied 11 agronomic

C. Brondani; P. Rangel; R. Brondani; M. Ferreira

2002-01-01

109

Hordeum vulgare Seedlings Amine Oxidase  

PubMed Central

Although no amine oxidase could be detected in crude extracts, the enzyme has been purified to apparent homogeneity from Hordeum vulgare seedlings using ammonium sulfate precipitation and chromatography on DEAE cellulose, Hydroxylapatite, and Sephadex G200 columns. Gel filtration experiments indicate a molecular weight of about 150,000. The pH optimum of the enzyme was found to be 7.5 in potassium phosphate buffer. The spectrum of ultraviolet and visible regions were similar to Cuamine oxidase from Leguminosae. PMID:16667542

Cogoni, Antonina; Piras, Carla; Farci, Raffaele; Melis, Antonello; Floris, Giovanni

1990-01-01

110

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

PubMed

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

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

2009-10-28

111

?-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

112

Isolation and characterisation of catechol-like siderophore from cowpea Rhizobium RA1  

Microsoft Academic Search

Cowpea Rhizobium RA-1 produced a catechol-like siderophore. Secondary hydroxamic acids were not detected. Bioassay of the siderophore exhibited a distinct zone of growth of cowpea rhizobia. One litre of culture filtrate gave 6.2 mg of catechol-like siderophore. Glycine and threonine were detected in the siderophore. Maximum production of siderophore was found at 36 h of growth of cowpea Rhizobium RA-1.

Mayuranki Modi; K. S. Shah; V. V. Modi

1985-01-01

113

Surface water enhances the uptake and photoreactivity of gaseous catechol on solid iron(III) chloride.  

PubMed

Uptake and photoreactivity of catechol-Fe complexes are investigated at the gas/solid interface under humid and dry conditions, along with the nature of the hydrogen-bonding network of adsorbed water. Catechol was chosen as a simple model for organics in aerosols. Iron chloride was used to distinguish ionic mobility from binding to coordinated iron(III) in hematite. Studies were conducted using diffuse reflectance infrared Fourier transform spectroscopy as a function of irradiation time. Results show that adsorbed water at 30% relative humidity (RH), not light, increases the concentration of adsorbed catechol by a factor of 3 over 60 min relative to dry conditions. Also, our data show that, at 30% RH and under light and dark conditions, growth factors describing the concentration of adsorbed catechol are very similar suggesting that light does not significantly enhance the uptake of catechol vapor on FeCl3. Surface water also enhances the initial photodecay kinetics of catechol-Fe complexes at 30% RH by a factor of 10 relative to control experiments (RH < 1%, or no FeCl3 under humid conditions). Absorptions assigned to carbonyl groups were not observed with irradiation time, which was explained by the dominance of FeCl(2+) species relative to FeOH(2+) in the highly acidic "quasi-liquid" phase at 30% RH. Clear differences in the hydrogen-bonding network upon gaseous catechol uptake are observed in the dark and light and during the photodecay of adsorbed catechol. The implications of these results on our understanding of interfacial processes in aged iron-containing surfaces are discussed. PMID:24295105

Tofan-Lazar, Julia; Al-Abadleh, Hind A

2014-01-01

114

Degradation of Fluorobenzene by Rhizobiales Strain F11 via ortho Cleavage of 4-Fluorocatechol and Catechol  

Microsoft Academic Search

The aerobic metabolism of fluorobenzene by Rhizobiales sp. strain F11 was investigated. Liquid chromatography-mass spectrometry analysis showed that 4-fluorocatechol and catechol were formed as intermediates during fluorobenzene degradation by cell suspensions. Both these compounds, unlike 3-fluorocatechol, supported growth and oxygen uptake. Cells grown on fluorobenzene contained enzymes for the ortho pathway but not for meta ring cleavage of catechols. The

Irina S. Moreira; Maria Isabel M. Ferreira; Maria F. Carvalho; Paula M. L. Castro; Dick B. Janssen

2006-01-01

115

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

PubMed Central

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

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

2002-01-01

116

Catecholamines oxidation by xanthine oxidase  

Microsoft Academic Search

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

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

1997-01-01

117

Antifungal Tradecraft by Cholesterol Oxidase  

PubMed Central

Summary In this issue of Chemistry & Biology, Aparicio and coworkers report that secreted bacterial cholesterol oxidase is required for the biosynthesis of the antifungal polyene pimaricin by Streptomyces natalensis [1]. Their discovery expands the inventory of tasks this biotechnologically important enzyme performs. PMID:17379137

Nesbitt, Natasha M.; Sampson, Nicole S.

2013-01-01

118

Polyphenol oxidase and photosynthesis research  

Microsoft Academic Search

Very briefly, the present state of knowledge on the latent, lumen oriented polyphenol oxidase (PPO) of the chloroplast is reviewed. The location of PPO in the thylakoid membrane was described by D. Arnon 46 years ago. The N-terminus sequence of the spinach enzyme is reported. A historical sketch is given of the discovery of photophosphorylation and Arnon's visit to the

Achim Trebst; Brigitte Depka

1995-01-01

119

Chromate reduction by rabbit liver aldehyde oxidase  

SciTech Connect

Chromate was reduced during the oxidation of 1-methylnicotinamide chlorine by partially purified rabbit liver aldehyde oxidase. In addition to l-methylnicotinamide, several other electron donor substrates for aldehyde oxidase were able to support the enzymatic chromate reduction. The reduction required the presence of both enzyme and the electron donor substrate. The rate of the chromate reduction was retarded by inhibitors or aldehyde oxidase but was not affected by substrates or inhibitors of xanthine oxidase. These results are consistent with the involvement of aldehyde oxidase in the reduction of chromate by rabbit liver cytosolic enzyme preparations.

Banks, R.B.; Cooke, R.T. Jr.

1986-05-29

120

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

Microsoft Academic Search

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

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

2000-01-01

121

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

PubMed

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

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

2012-01-01

122

Characterization of the gene encoding an extracellular laccase of Myceliophthora thermophila and analysis of the recombinant enzyme expressed in Aspergillus oryzae.  

PubMed Central

A genomic DNA segment encoding an extracellular laccase was isolated from the thermophilic fungus Myceliophthora thermophila, and the nucleotide sequence of this gene was determined. The deduced amino acid sequence of M. thermophila laccase (MtL) shows homology to laccases from diverse fungal genera. A vector containing the M. thermophila laccase coding region, under transcriptional control of an Aspergillus oryzae alpha-amylase gene promoter and terminator, was constructed for heterologous expression in A. oryzae. The recombinant laccase expressed in A. oryzae was purified to electrophoretic homogeneity by anion-exchange chromatography. Amino-terminal sequence data suggests that MtL is synthesized as a preproenzyme. The molecular mass was estimated to be approximately 100 to 140 kDa by gel filtration on Sephacryl S-300 and to be 85 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Carbohydrate analysis revealed that MtL contains 40 to 60% glycosylation. The laccase shows an absorbance spectrum that is typical of blue copper oxidases, with maxima at 276 and 589 nm, and contains 3.9 copper atoms per subunit. With syringaldazine as a substrate, MtL has optimal activity at pH 6.5 and retains nearly 100% of its activity when incubated at 60 degrees C for 20 min. This is the first report of the cloning and heterologous expression of a thermostable laccase. PMID:9251203

Berka, R M; Schneider, P; Golightly, E J; Brown, S H; Madden, M; Brown, K M; Halkier, T; Mondorf, K; Xu, F

1997-01-01

123

Model sclerotization studies. 4. Generation of N-acetylmethionyl catechol adducts during tyrosinase-catalyzed oxidation of catechols in the presence of N-acetylmethionine.  

PubMed

Incubation of catechol with mushroom tyrosinase in the presence of N-acetylmethionine resulted in the generation of an adduct. This product was identified to be N-acetylmethionyl catechol, on the basis of spectral characteristics and well-characterized chemical reaction of o-benzoquinone with N-acetylmethionine. Enzyme-catalyzed oxidation of catechol and the subsequent nonenzymatic addition of the resultant quinone to N-acetylmethionine accounted for the observed reaction. That the reaction is not confined to catechol alone, but is of general occurrence, can be demonstrated by the facile generation of similar adducts in incubation mixtures containing N-acetylmethionine, tyrosinase, and different N-acetylmethionines, such as 4-methylcatechol and N-acetyldopamine. Attempts to duplicate the reaction with insect cuticular phenoloxidases were not successful, as the excess N-acetylmethionine used in the reaction inhibited their activity. Nevertheless, occurrence of this nonenzymatic reactivity. Nevertheless, occurrence of this nonenzymatic reaction between N-acetylmethionine and mushroom tyrosinase-generated quinones indicates that a similar reaction between enzymatically generated quinones in the cuticle with protein-bound methionine moiety is likely to occur during in vivo quinone tanning as well. PMID:9589603

Sugumaran, M; Nelson, E

1998-01-01

124

21 CFR 173.130 - Carbohydrase derived from Rhizopus oryzae.  

Code of Federal Regulations, 2011 CFR

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

2011-04-01

125

21 CFR 173.130 - Carbohydrase derived from Rhizopus oryzae.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

126

21 CFR 173.130 - Carbohydrase derived from Rhizopus oryzae.  

Code of Federal Regulations, 2014 CFR

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

2014-04-01

127

21 CFR 173.130 - Carbohydrase derived from Rhizopus oryzae.  

Code of Federal Regulations, 2012 CFR

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

2012-04-01

128

21 CFR 173.130 - Carbohydrase derived from Rhizopus oryzae.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

129

Draft Genome Sequence of Lactobacillus oryzae Strain SG293T  

PubMed Central

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

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

2014-01-01

130

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

131

Improving Pharmaceutical Protein Production in Oryza sativa.  

PubMed

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

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

2013-01-01

132

Improving Pharmaceutical Protein Production in Oryza sativa  

PubMed Central

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

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

2013-01-01

133

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

134

A rapid and sensitive assay method for measuring amine oxidase based on hydrogen peroxide-titanium complex formation.  

PubMed

Hydrogenperoxide (H(2)O(2)) is an end product of diamine and polyamine oxidation by their respective oxidase enzymes. A new sensitive assay method is based on a H(2)O(2)-titanium (Ti) complex formation as an indicator of H(2)O(2) production due to polyamine oxidation. The orange-yellow coloured H(2)O(2)-Ti complex was measured at 410 nm in a Shimadzu spectrophotometer. The assay conditions for maximum diamine oxidase (DAO) and polyamine oxidase (PAO) as standardized here using the hypocotyl tissues of Vigna catjang Endl. cv Pusa Barsati consisted of pH 7.4 (40 mM potassium phosphate buffer), 3 mM substrate (putrescine or spermine), 37 degrees C incubation temperature and 30 min incubation time in the presence of catechol (10(-2) M) used as an inhibitor of both peroxidase and catalase activity. The method described here was significantly more sensitive than the starch-iodide method [T.A. Smith, Biochem. Biophys. Res. Commun. 41 (1970) 1452-1456], which could be improved further if measured under the same assay conditions as described for the H(2)O(2)-Ti method. Sensitivity of the present method was tested by assaying DAO/PAO activity in auxin treated hypocotyls of Vigna and comparing it with the starch-iodide method in two other plant samples. PMID:10960728

Nag; Saha; Choudhuri

2000-08-22

135

Genetic characterization of red rice (Oryza sativa L.) and control in imidazolinone tolerant rice (Oryza sativa L.)  

E-print Network

Red rice from the southern United States was collected and analyzed using Simple Sequence Length Polymorphism (SSLP) markers in an effort to test the assumption that red rice is Oryza sativa ssp. indica. The 18 markers used are distributed across...

Ottis, Brian Vance

2002-01-01

136

Molecular cloning of human liver sulfite oxidase.  

PubMed

A 2.4 kilobase cDNA clone of human sulfite oxidase was isolated from a human liver cDNA library in lambda gt10. Comparison of three sulfite oxidase sequences to several plant and fungal nitrate reductase sequences reveals a single conserved cysteine with highly conserved flanking sequences. The conserved cysteine is postulated to be a ligand of molybdenum in sulfite oxidase and nitrate reductase. PMID:7599189

Garrett, R M; Bellissimo, D B; Rajagopalan, K V

1995-06-01

137

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

Microsoft Academic Search

Bacterial leaf blight (BLB), caused by Xanthomonas oryzae pv. oryzae (Xoo), gives rise to devastating crop losses in rice. Disease resistant rice cultivars are the most economical way to combat the\\u000a disease. The TP309 cultivar is susceptible to infection by Xoo strain PXO99. A transgenic variety, TP309_Xa21, expresses the pattern recognition receptor Xa21, and is resistant. PXO99?raxST, a strain lacking

Theodore R. Sana; Steve Fischer; Gert Wohlgemuth; Anjali Katrekar; Ki-hong Jung; Pam C. Ronald; Oliver Fiehn

2010-01-01

138

Characterization of an Alien Chromosome of Oryza officinalis Transferred the Genomic and Cytological Environment of Oryza sativa  

Microsoft Academic Search

Distant hybridization between rice species and their genome interactions have become the hot points of genetic research. The\\u000a new formed hybrid was unstable and many of the alien chromosomes would be excluded out in the meiosis procedure. In this study,\\u000a we investigated the phenomenon that the monosomic alien addition lines (MAALs) of Oryza officinalis (CC)–Oryza sativa (AA) inherited in the

Gang Li; Ming Tang; Wei Hu; Guangcun He; Hong Liu; Xuequn Liu; Rui Qin

2010-01-01

139

Functional analysis of Xa3\\/Xa26 family members in rice resistance to Xanthomonas oryzae pv. oryzae  

Microsoft Academic Search

Plant disease resistant (R) genes are frequently clustered in the genome. The diversity of members in a complex R-gene family may provide variation in resistance specificity. Rice Xa3\\/Xa26, conferring resistance to Xanthomonas\\u000a oryzae pv. oryzae (Xoo) encodes a leucine-rich repeat (LRR) receptor kinase-type protein and belongs to a multigene family, consisting of Xa3\\/Xa26, MRKa, MRKc and MRKd in rice cultivar

Yinglong Cao; Liu Duan; Hongjing Li; Xinli Sun; Yu Zhao; Caiguo Xu; Xianghua Li; Shiping Wang

2007-01-01

140

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

141

Arsenite oxidase also functions as an antimonite oxidase.  

PubMed

Arsenic and antimony are toxic metalloids and are considered priority environmental pollutants by the U.S. Environmental Protection Agency. Significant advances have been made in understanding microbe-arsenic interactions and how they influence arsenic redox speciation in the environment. However, even the most basic features of how and why a microorganism detects and reacts to antimony remain poorly understood. Previous work with Agrobacterium tumefaciens strain 5A concluded that oxidation of antimonite [Sb(III)] and arsenite [As(III)] required different biochemical pathways. Here, we show with in vivo experiments that a mutation in aioA [encoding the large subunit of As(III) oxidase] reduces the ability to oxidize Sb(III) by approximately one-third relative to the ability of the wild type. Further, in vitro studies with the purified As(III) oxidase from Rhizobium sp. strain NT-26 (AioA shares 94% amino acid sequence identity with AioA of A. tumefaciens) provide direct evidence of Sb(III) oxidation but also show a significantly decreased Vmax compared to that of As(III) oxidation. The aioBA genes encoding As(III) oxidase are induced by As(III) but not by Sb(III), whereas arsR gene expression is induced by both As(III) and Sb(III), suggesting that detection and transcriptional responses for As(III) and Sb(III) differ. While Sb(III) and As(III) are similar with respect to cellular extrusion (ArsB or Acr3) and interaction with ArsR, they differ in the regulatory mechanisms that control the expression of genes encoding the different Ars or Aio activities. In summary, this study documents an enzymatic basis for microbial Sb(III) oxidation, although additional Sb(III) oxidation activity also is apparent in this bacterium. PMID:25576601

Wang, Qian; Warelow, Thomas P; Kang, Yoon-Suk; Romano, Christine; Osborne, Thomas H; Lehr, Corinne R; Bothner, Brian; McDermott, Timothy R; Santini, Joanne M; Wang, Gejiao

2015-03-15

142

Synthesis and in vitro antibacterial activity of spermidine-based mixed catechol- and hydroxamate-containing siderophore—Vancomycin conjugates  

Microsoft Academic Search

The first antibiotic conjugates of vancomycin (1) and siderophore analogues containing spermidine-based catechol ligands (conjugate 11) as well as mixed catechol and hydroxamate ligands (conjugate 13) are described. The design of the conjugates was based on the earlier observation that conjugation of siderophore components to ?-lactam antibiotics induced active iron transport-mediated drug delivery. The novel conjugates (11 and 13) were

Manuka Ghosh; Marvin J. Miller

1996-01-01

143

A new sensitive and selective spectrophotometric method for the determination of catechol derivatives and its pharmaceutical preparations  

Microsoft Academic Search

A sensitive and simple spectrophotometric method for the estimation of certain catechol derivatives like pyrocatechol (PCL), dopamine hydrochloride (DPH), levodopa (LDP), methyl dopa (MDP) and adrenaline (ADH) in either pure form or in its pharmaceutical formulation is described. The method is based on the interaction of diazotised p-nitro aniline (DPNA) with catechol derivatives in presence of molybdate ions in acidic

P. Nagaraja; R. A. Vasantha; K. R. Sunitha

2001-01-01

144

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

PubMed Central

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

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

2012-01-01

145

Comparative effects of Saccharomyces cerevisiae and Aspergillus oryzae on rumen fermentations  

E-print Network

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

Boyer, Edmond

146

Catechol chemistry inspired approach to construct self-cross-linked polymer nanolayers as versatile biointerfaces.  

PubMed

In this study, we proposed a catechol chemistry inspired approach to construct surface self-cross-linked polymer nanolayers for the design of versatile biointerfaces. Several representative biofunctional polymers, P(SS-co-AA), P(SBMA-co-AA), P(EGMA-co-AA), P(VP-co-AA), and P(MTAC-co-AA), were first synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization, and then the catecholic molecules (dopamine, DA) were conjugated to the acrylic acid (AA) units by the facile carbodiimide chemistry. Then, the catechol (Cat) group conjugated biofunctional polymers, named PSS-Cat, PSBMA-Cat, PEGMA-Cat, PVP-Cat, and PMTAC-Cat, were applied for the construction of self-cross-linked nanolayers on polymeric substrates via the pH induced catechol cross-linking and immobilization. The XPS spectra, surface morphology, and wettability gave robust evidence that the catechol conjugated polymers were successfully coated, and the coated substrates possessed increased surface roughness and hydrophilicity. Furthermore, the systematic in vitro investigation of protein adsorption, platelet adhesion, activated partial thromboplastin time (APTT), thrombin time (TT), cell viability, and antibacterial ability confirmed that the coated nanolayers conferred the substrates with versatile biological performances. The PSS-Cat coated substrate had low blood component activation and excellent anticoagulant activity; while the PEGMA-Cat and PSBMA-Cat showed ideal resistance to protein fouling and inhibition of platelet activation. The PSS-Cat and PVP-Cat coated substrates exhibited promoted endothelial cell proliferation and viability. The PMTAC-Cat coated substrate showed an outstanding activity on bacterial inhibition. In conclusion, the catechol chemistry inspired approach allows the self-cross-linked nanolayers to be easily immobilized on polymeric substrates with the stable conformation and multiple biofunctionalities. It is expected that this low-cost and facile bioinspired coating system will present great potential in creating novel and versatile biointerfaces. PMID:25420156

Liu, Xinyue; Deng, Jie; Ma, Lang; Cheng, Chong; Nie, Chuanxiong; He, Chao; Zhao, Changsheng

2014-12-16

147

Nuclear Localization of Catechol-O-Methyltransferase in Neoplastic and Nonneoplastic Mammary Epithelial Cells  

PubMed Central

Catechol-O-methyltransferase (COMT) plays both a regulatory and protective role in catechol homeostasis. It contributes to the regulation of tissue levels of catecholamines and catecholestrogens (CEs) and, by blocking oxidative metabolism of catechols, prevents endogenous and exogenous catechols from becoming a source of potentially mutagenic electrophiles. Evidence implicating CEs in carcinogenesis, in particular in the hamster kidney model of estrogen-induced cancer, has focused attention on the protective role of COMT in estrogen target tissues. We have previously reported that treating hamsters with estrogens causes translocation of COMT to nuclei of epithelial cells in the renal cortex, the site of CE biosynthesis and where the cancers arise. This finding suggested that nuclear COMT may be a marker of a threat to the genome by catechols, including CEs. It is postulated that CEs play a role in the genesis of breast cancer by contributing to a state of chronic oxidative stress that is presumed to underlie the high incidence of this disease in the United States. Therefore, here we used immunocytochemistry to re-examine human breast parenchyma for nuclear COMT. In addition to confirming previous reports of cytoplasmic COMT in mammary epithelial cells, we identified nuclear COMT in foci of mammary epithelial cells in histologically normal breast tissue of virtually all control (macromastia) and cancer patients and in breast cancer cells. There was no correlation between tissue histology and the numbers of cells with nuclear COMT, the size of foci containing such cells, or intensity of nuclear COMT immunostaining. The focal nature of the phenomenon suggests that nuclear COMT does not serve a housekeeping function but that it reflects a protective response to an increased local catechol load, presumably of CEs and, as such, that it may be a characteristic of the population of women studied who share the same major risk factor for developing breast cancer, that of living in the industrialized West. PMID:10854207

Weisz, Judith; Fritz-Wolz, Gabriella; Gestl, Shelley; Clawson, Gary A.; Creveling, Cyrus R.; Liehr, Joachim G.; Dabbs, David

2000-01-01

148

The effect of catechol on human peripheral blood mononuclear cells (in vitro study).  

PubMed

Catechol also known as pyrocatechol or 1,2-dihydroxybenzene is formed endogenously in the organism from neurotransmitters including adrenaline, noradrenaline, and dopamine. It is also a metabolite of many drugs like DOPA, isoproterenol or aspirin and it is also formed in the environment during transformation of various xenobiotics. We evaluated in vitro the effect of catechol on the structure and function of human peripheral blood mononuclear cells (PBMCs). The cells were incubated with xenobiotic at concentration range from 2 to 500?g/mL for 1h. Human blood mononuclear cells were obtained from leucocyte-platelet buffy coat taken from healthy donors in the Blood Bank of ?ód?, Poland. Using flow cytometry we have evaluated necrotic, apoptotic and morphological changes in PBMCs incubated with catechol. Moreover, we have estimated changes in reactive oxygen species (ROS) formation, protein carbonylation and lipid peroxidation in the cells studied. The compound studied provoked necrotic (from 250?g/mL), apoptotic (from 100?g/mL), and morphological changes (from 250?g/mL) in the incubated cells. We have also noted that catechol decreased H2DCF oxidation at 2 and 10?g/mL but at higher concentrations of 250 and 500?g/mL it caused statistically significant increase in the oxidation of this probe. We also observed an increase in lipid peroxidation (from 250?g/mL) and protein carbonylation (from 50?g/mL) of PBMCs. It was observed that catechol only at high concentrations was capable of inducing changes in PBMCs. The obtained results clearly showed that catechol may induce change in PBMCs only in the caste of poisoning with this compound. PMID:25528409

Bukowska, Bo?ena; Micha?owicz, Jaromir; Marczak, Agnieszka

2015-01-01

149

Unexpected formation of a novel pyridinium-containing catecholate ligand and its manganese(III) complex.  

PubMed

Nucleophilic aromatic substitution of tetrachloro-o-benzoquinone by pyridine and reduction of the o-quinone to the catechol by hydroxylamine forms 1,2-dihydroxy-3,5,6-trichlorobenzene-4-pyridinium chloride. This compound reacts with manganese(II) acetate in air to form chlorobis(3,5,6-trichlorobenzene 4-pyridinium catecholate)manganese(III), which represents the first complex of this ligand class to be structurally characterized by X-ray diffraction; this complex is active in the catalytic reduction of dioxygen to hydrogen peroxide under ambient conditions and turnover frequencies (TOFs) >10,000 h(-1) can be obtained. PMID:20023930

Sheriff, Tippu S; Watkinson, Michael; Motevalli, Majid; Lesin, Jocelyne F

2010-01-01

150

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

PubMed

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

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

2015-04-15

151

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

152

Factors Affecting Reaction Kinetics of Glucose Oxidase  

Microsoft Academic Search

Basic principles of enzyme kinetics are demonstrated using the enzyme glucose oxidase. The glucose oxidase enzymatic reaction is coupled to horseradish peroxidase, which in turn catalyzes the oxidation of a dye to a bright blue-green color. The appearance of the blue-green dye is used to monitor the course of the reaction and is quite visible in a classroom setting. A

Kristin A. Johnson

2002-01-01

153

Evaluation of antioxidant, lipid, and protein fractions of accessions of Oryza Species.  

Technology Transfer Automated Retrieval System (TEKTRAN)

The genus Oryza has given rise to rice (Oryza sativa L.), a major source of food for much of the human population. The Oryza genus is small, including only 23 species, but it is remarkably diverse in terms of its ecological adaptation. This diversity may not only be restricted to ecological characte...

154

Identification and QTL mapping of blast resistance in wild Oryza species  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

155

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

156

Quantitative determination of catecholic degradation products from insect sclerotized cuticles.  

PubMed

Acid hydrolysates of cuticle from various insect species were quantitatively analyzed for five catecholic amino acid adducts. Four of the adducts are ketocatechols; in three of them the amino acid moiety, either lysine, glycine or beta-alanine, is connected via its amino group to the alpha-carbon atom of 3,4-dihydroxyacetophenone, in the fourth a tyrosine residue is connected to the same position via its phenolic group. The fifth adduct contains histidine linked via its imidazole-ring to the beta-position of the dopamine sidechain. The three ketocatecholic adducts containing alpha-amino acids were obtained in significant yields from adult cuticles of the locust Schistocerca gregaria, the cockroaches Blaberus craniifer and Periplaneta americana, and the beetles Pachynoda sinuata and Tenebrio molitor, but only in trace amounts from larval and pupal cuticles of T. molitor, pupal cuticles of the moths Manduca sexta and Hyalophora cecropia, and puparia of the blowfly Calliphora vicina. The beta-alanine-containing ketocatechol was not obtained from cuticle of locusts and T. molitor larvae and pupae, but it was present in the hydrolysates of the other cuticles. The beta-histidine-dopamine adduct was obtained from all the cuticles, the highest yield was obtained from adult P. sinuata and the lowest yield was from adult S. gregaria. The beta-histidine-dopamine adduct is derived from the product formed by reaction of p-quinone methides of N-acetyldopamine (NADA) or N-beta-alanyldopamine (NBAD) with histidine residues in the cuticular proteins. The ketocatecholic adducts are assumed to be degradation products of crosslinks formed when oxidized dehydro-NADA reacts with the cuticular proteins. The insect species investigated appear to use both pathways for sclerotization, but to widely differing extents; the dehydro-NADA pathway dominates in cuticles which are exposed to strong deforming forces, such as those of adult locusts and cockroaches, and the p-quinone methide pathway dominates in cuticle of lepidopteran pupae and blowfly puparia, which are not exposed to strong mechanical forces but have to be effectively protected against microbial and fungal attacks. PMID:18675913

Andersen, Svend Olav

2008-09-01

157

Chitosan-catechol: A polymer with long-lasting mucoadhesive properties.  

PubMed

Numerous mucoadhesive polymers have been exploited for prolonging the residence time of formulated drugs or pharmaceuticals at specific delivery sites. However, it has been difficult to achieve satisfactory mucoadhesive properties. The two major modification strategies such as thiolation or lectin functionalization have been extensively studied, but disulfide bond reversibility in the case of thiolation and the toxicity of lectins have been problems. Thus, approaches for further improvement of mucoadhesive properties need to be developed. With an overwhelming library of mucoadhesive polymers, one practical way to improve mucoadhesion is chemical modification of existing mucoadhesive polymers. In other words, the method is based on utilizing the cooperative effect that might be achieved by chemical tethering of a small adhesive moiety to an available mucoadhesive polymer. Here, we conjugated catechols derived from mussel adhesive proteins to chitosan, which is a widely known mucoadhesive polymer. We demonstrated that the gastrointestinal (GI) tract retention of chitosan-catechol was improved compared to unmodified chitosan, which is due to the formation of irreversible catechol mediated-crosslinking with mucin. The results indicate that catechol modification of mucoadhesive polymers may possibly lead to a new generation of mucoadhesive polymers for mucosal drug delivery. PMID:25818422

Kim, Kyuri; Kim, Keumyeon; Ryu, Ji Hyun; Lee, Haeshin

2015-06-01

158

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

159

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

160

Salicylate and catechol levels are maintained in nahG transgenic poplar  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

161

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

E-print Network

methods. For three of the products, the E value and EMY (effective mass yield, is defined as the percentage of the mass of desired product relative to the mass of all non-benign materials in its synthesis the green component of the preparation. Potential for direct introduction of the catechol unit to various

Hudlicky, Tomas

162

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

163

Salicylate and catechol levels are maintained in nahG transgenic poplar  

Microsoft Academic Search

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

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

2007-01-01

164

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

PubMed Central

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

Klecka, G M; Gibson, D T

1981-01-01

165

Potentiometric and spectroscopic studies on aluminium(III) complexes of some catechol derivatives.  

PubMed

The interactions of aluminium(III) ion with the triprotic catechol derivatives (H3L), 2,3-dihydroxybenzoic acid (2,3-DHBA), 3,4-dihydroxyphenylacetic acid (3,4-DHPA), 3,4-dihydroxybenzoic acid (3,4-DHBA), and 3,4-dihydroxyhydrocinnamic acid (3,4-DHHCA) were investigated in aqueous solution at 25.0 degrees C. The Calvin-Bjerrum titration method was adopted for the determination of formation constants of proton-ligand and aluminium(III)-ligand complexes. Potentiometric and spectroscopic results indicated that these catechol derivatives exhibit a true bidentate character. The chelation occurs via their catecholate sites, with the exception of 2,3-DHBA. In the case of 2,3-DHBA complexes, the dominant species are either the salicylate type (COO-, O-) or catecholate type (O-, O-) complex. The protonation constants of ligands and their formation constants of Al(III) complexes were also correlated. The order of decreasing stabilities of complexes is: 3,4-DHPA>3,4-DHBA>3,4-DHHCA>2,3-DHBA. PMID:15304983

Türkel, Naciye; Berker, Melek; Ozer, Ulviye

2004-08-01

166

Conductivity-Based Catechol Sensor Using Tyrosinase Immobilized in Porous Silicon  

Microsoft Academic Search

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

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

2008-01-01

167

Dietary inhibitors of monoamine oxidase A.  

PubMed

Inhibition of monoamine oxidase is one way to treat depression and anxiety. The information now available on the pharmacokinetics of flavonoids and of the components of tobacco prompted an exploration of whether a healthy diet (with or without smoking) provides active compounds in amounts sufficient to partially inhibit monoamine oxidase. A literature search was used to identify dietary monoamine oxidase inhibitors, the levels of these compounds in foods, the pharmacokinetics of the absorption and distribution, and tissue levels observed. An estimated daily intake and the expected tissue concentrations were compared with the measured efficacies of the compounds as inhibitors of monoamine oxidases. Norharman, harman and quercetin dietary presence, pharmacokinetics, and tissue levels were consistent with significant levels reaching neuronal monoamine oxidase from the diet or smoking; 1,2,3,4-tetrahydroisoquinoline, eugenol, 1-piperoylpiperidine, and coumarin were not. Quercetin was equipotent with norharman as a monoamine oxidase A inhibitor and its metabolite, isorhamnetin, also inhibits. Total quercetin was the highest of the compounds in the sample diet. Although bioavailability was variable depending on the source, a healthy diet contains amounts of quercetin that might give sufficient amounts in brain to induce, by monoamine oxidase A inhibition, a small decrease in neurotransmitter breakdown. PMID:21190052

Dixon Clarke, Sarah E; Ramsay, Rona R

2011-07-01

168

Cyclopiazonic Acid Biosynthesis of Aspergillus flavus and Aspergillus oryzae  

PubMed Central

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

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

2009-01-01

169

Structural Insights into Sulfite Oxidase Deficiency  

SciTech Connect

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

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

2005-01-01

170

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

PubMed

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

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

1996-03-01

171

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

PubMed

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

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

2014-12-16

172

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

PubMed

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

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

2014-12-15

173

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

174

Human lysyl oxidase-like 2.  

PubMed

Lysyl oxidase like-2 (LOXL2) belongs to the lysyl oxidase (LOX) family, which comprises Cu(2+)- and lysine tyrosylquinone (LTQ)-dependent amine oxidases. LOXL2 is proposed to function similarly to LOX in the extracellular matrix (ECM) by promoting crosslinking of collagen and elastin. LOXL2 has also been proposed to regulate extracellular and intracellular cell signaling pathways. Dysregulation of LOXL2 has been linked to many diseases, including cancer, pro-oncogenic angiogenesis, fibrosis and heart diseases. In this review, we will give an overview of the current understandings and hypotheses regarding the molecular functions of LOXL2. PMID:25146937

Moon, Hee-Jung; Finney, Joel; Ronnebaum, Trey; Mure, Minae

2014-12-01

175

The Interaction of Propanil+Thiobencarb with Imazethapyr and Imazamox for Enhanced Red Rice (Oryza spp.) Control in Imidazolinone-Tolerant Rice (Oryza sativa L.)  

E-print Network

rice (Oryza sativa L.), barnyardgrass (Echinochloa crus-galli L.), broadleaf signalgrass (Brachiaria platyphylla L.), ducksalad (Heteranthera limosa L.), junglerice (Echinochloa colonum L), alligatorweed (Alternanthera philoxeroides L.), yellow...

Jones, Trevor Nelson

2014-04-28

176

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

PubMed Central

Background Nonhost resistance is a generalized, durable, broad-spectrum resistance exhibited by plant species to a wide variety of microbial pathogens. Although nonhost resistance is an attractive breeding strategy, the molecular basis of this form of resistance remains unclear for many plant-microbe pathosystems, including interactions with the bacterial pathogen of rice, Xanthomonas oryzae pv. oryzae (Xoo). Methods and Findings Virus-induced gene silencing (VIGS) and an assay to detect the hypersensitive response (HR) were used to screen for genes required for nonhost resistance to Xoo in N. benthamiana. When infiltrated with Xoo strain YN-1, N. benthamiana plants exhibited a strong necrosis within 24 h and produced a large amount of H2O2 in the infiltrated area. Expression of HR- and defense-related genes was induced, whereas bacterial numbers dramatically decreased during necrosis. VIGS of 45 ACE (Avr/Cf-elicited) genes revealed identified seven genes required for nonhost resistance to Xoo in N. benthamiana. The seven genes encoded a calreticulin protein (ACE35), an ERF transcriptional factor (ACE43), a novel Solanaceous protein (ACE80), a hydrolase (ACE117), a peroxidase (ACE175) and two proteins with unknown function (ACE95 and ACE112). The results indicate that oxidative burst and calcium-dependent signaling pathways play an important role in nonhost resistance to Xoo. VIGS analysis further revealed that ACE35, ACE80, ACE95 and ACE175, but not the other three ACE genes, interfered with the Cf-4/Avr4-dependent HR. Conclusions/Significance N. benthamiana plants inoculated with Xoo respond by rapidly eliciting an HR and nonhost resistance. The oxidative burst and other signaling pathways are pivotal in Xoo-N. benthamiana nonhost resistance, and genes involved in this response partially overlap with those involved in Cf/Avr4-dependent HR. The seven genes required for N. benthamiana-mediated resistance to Xoo provide a basis for further dissecting the molecular mechanism of nonhost resistance. PMID:22912739

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

2012-01-01

177

Protonmotive Mechanism of Heme-Copper Oxidases  

Microsoft Academic Search

The mechanism of coupling of proton and electron transfer in oxidases is reviewed and related to the structural information that is now available. A “glutamate trap” mechanism for proton\\/electron coupling is described.

P. R. Rich; S. Jünemann; B. Meunier

1998-01-01

178

CBS domain-containing proteins are Rhizopus oryzae ferrioxamine receptors  

Technology Transfer Automated Retrieval System (TEKTRAN)

Background: Iron-overload patients treated with deferoxamine are uniquely susceptible to mucormycosis, because Rhizopus spp. can obtain iron from ferrioxamine (deferoxamine + Fe**3+). Previously we have identified two closely related, ferrioxamine-inducible R. oryzae genes (FOB1 and FOB2) in which ...

179

Plant regeneration from protoplasts of wild rice ( Oryza rufipogon Griff.)  

Microsoft Academic Search

Embryogenic callus initiated from basal segments of micropropagated shoots of Oryza rufipogon were used to initiate cell suspension cultures. After approximately 3 months these cultures were capable of yielding large numbers of protoplasts which underwent sustained division in agarose-solidified medium at a frequency comparable to that observed with Japonica rice protoplasts in previous studies. O. rufipogon plants were reproducibly regenerated

Abdul Baset; Robert P. Finch; Edward C. Cocking

1991-01-01

180

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

181

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

182

The Purification of Polyphenol Oxidase from Tobacco  

Microsoft Academic Search

A new polyphenol oxidase (PPO) named PPO II was purified from tobacco (Nicotiana tobacum) by using acetone powder, ammonium sulfate precipitation, and column chromatography on DEAE-Sephadex A-50, Sephadex G-75, and CM-Sephadex C-50. It has an active site of a pair of type 3 coppers bridged to phenolate oxygen, which represents a new catalytic mechanism for polyphenol oxidase. PAGE, SDS-PAGE, and

Chunhua Shi; Ya Dai; Xiaolong Xu; Yongshu Xie; Qingliang Liu

2002-01-01

183

PPAR? and Proline Oxidase in Cancer  

PubMed Central

Proline is metabolized by its own specialized enzymes with their own tissue and subcellular localizations and mechanisms of regulation. The central enzyme in this metabolic system is proline oxidase, a flavin adenine dinucleotide-containing enzyme which is tightly bound to mitochondrial inner membranes. The electrons from proline can be used to generate ATP or can directly reduce oxygen to form superoxide. Although proline may be derived from the diet and biosynthesized endogenously, an important source in the microenvironment is from degradation of extracellular matrix by matrix metalloproteinases. Previous studies showed that proline oxidase is a p53-induced gene and its overexpression can initiate proline-dependent apoptosis by both intrinsic and extrinsic pathways. Another important factor regulating proline oxidase is peroxisome proliferator activated receptor gamma (PPAR?). Importantly, in several cancer cells, proline oxidase may be an important mediator of the PPAR?-stimulated generation of ROS and induction of apoptosis. Knockdown of proline oxidase expression by antisense RNA markedly decreased these PPAR?-stimulated effects. These findings suggest an important role in the proposed antitumor effects of PPAR?. Moreover, it is possible that proline oxidase may contribute to the other metabolic effects of PPAR?. PMID:18670615

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

2008-01-01

184

The mammalian aldehyde oxidase gene family  

PubMed Central

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

2009-01-01

185

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

PubMed

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

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

2015-01-01

186

Toxicity of 5- chloro- 3- methyl- catechol to rat: Chemical observations and light microscopy of the tissue  

Microsoft Academic Search

5-chloro-3-methyl-catechol was first time described by GAUNT and EVANS (1961) as a metabolite of MCPA (4-chloro-2-methylphenoxyacetic aci~which is the most widely used herbicide in the Nordic countries. The toxicity of the metabolite 5-chloro-3-methylcatechol bas hot been studied so far. Other catechols like 3,5dichlorocatechol has been shown to be a metabollte of 2,4-D (BOLLAG et ai. 1968a, BOLLAG et ai. 1968b),

Marja Liisa Hattuia; Hilkka Reunanen; Raimo Krees; Antti U. Arstila; Juha Knuutinen

1979-01-01

187

pH-dependent cross-linking of catechols through oxidation via Fe(3+) and potential implications for mussel adhesion.  

PubMed

The mussel byssus is a remarkable attachment structure that is formed by injection molding and rapid in-situ hardening of concentrated solutions of proteins enriched in the catecholic amino acid 3,4-dihydroxy-L-phenylalanine (DOPA). Fe(3+), found in high concentrations in the byssus, has been speculated to participate in redox reactions with DOPA that lead to protein polymerization, however direct evidence to support this hypothesis has been lacking. Using small molecule catechols, DOPA-containing peptides, and native mussel foot proteins, we report the first direct observation of catechol oxidation and polymerization accompanied by reduction of Fe(3+) to Fe(2+). In the case of the small molecule catechol, we identified two dominant dimer species and characterized their connectivities by nuclear magnetic resonance (NMR), with the C6-C6 and C5-C6 linked species as the major and minor products, respectively. For the DOPA-containing peptide, we studied the pH dependence of the reaction and demonstrated that catechol polymerization occurs readily at low pH, but is increasingly diminished in favor of metal-catechol coordination interactions at higher pH. Finally, we demonstrate that Fe(3+) can induce cross-links in native byssal mussel proteins mefp-1 and mcfp-1 at acidic pH. Based on these findings, we discuss the potential implications to the chemistry of mussel adhesion. PMID:25243062

Fullenkamp, Dominic E; Barrett, Devin G; Miller, Dusty R; Kurutz, Josh W; Messersmith, Phillip B

2014-01-01

188

Natural compounds containing a catechol group enhance the formation of N?-(carboxymethyl)lysine of the Maillard reaction.  

PubMed

Inhibition of advanced glycation end-product (AGE) formation is a potential strategy for the prevention of clinical diabetes complications. Screening for new AGE inhibitors revealed several natural compounds that inhibited the formation of N(?)-(carboxymethyl)lysine (CML), a major antigenic AGE structure, whereas natural compounds containing a catechol group, such as gallic acid and epicatechin, significantly enhanced CML formation. A similar enhancing effect was also observed by culturing THP-1 macrophages in the presence of catechol compounds. Although 4-methylcatechol significantly enhanced CML formation from glycated HSA (gHSA), a model for Amadori proteins, analogues of catechol such as 5-methylresorcinol and methylhydroquinone showed no enhancing effect. Even though 1mM 4-methylcatechol, epicatechin, and gallic acid significantly enhanced CML formation from gHSA, it was significantly inhibited by decreasing their concentration. The enhancing effect of 1mM catechol compounds was inhibited in the presence of the glutathione peroxidase system, thus demonstrating that hydrogen peroxide generated from catechol compounds plays an important role in the enhancement of CML formation. Furthermore, administration of 500mg/kg/day epicatechin to STZ-induced diabetic mice for 45days enhanced CML accumulation at the surface area of gastric epithelial cells in the stomach. This study provides the first evidence that high amounts of catechol-containing structures enhance oxidative stress, thus leading to enhanced CML formation, and this phenomenon may explain the paradoxical effect that some flavonoids have on redox status. PMID:21195168

Fujiwara, Yukio; Kiyota, Naoko; Tsurushima, Keiichiro; Yoshitomi, Makiko; Mera, Katsumi; Sakashita, Naomi; Takeya, Motohiro; Ikeda, Tsuyoshi; Araki, Tomohiro; Nohara, Toshihiro; Nagai, Ryoji

2011-04-01

189

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

190

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

PubMed

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

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

2013-04-01

191

Targeting NADPH oxidases in vascular pharmacology  

PubMed Central

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

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

2012-01-01

192

Heme/copper terminal oxidases  

SciTech Connect

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

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

1996-11-01

193

Alternative oxidase and plastoquinol terminal oxidase in marine prokaryotes of the Sargasso Sea  

Microsoft Academic Search

Alternative oxidase (AOX) represents a non-energy conserving branch in mitochondrial electron transport while plastoquinol terminal oxidase (PTOX) represents a potential branch in photosynthetic electron transport. Using a metagenomics dataset, we have uncovered numerous and diverse AOX and PTOX genes from the Sargasso Sea. Sequence similarity, synteny and phylogenetic analyses indicate that the large majority of these genes are from prokaryotes.

Allison E. McDonald; Greg C. VanlerbergheT

2005-01-01

194

OsWRKY62 is a negative regulator of basal and Xa21-mediated defense against Xanthomonas oryzae pv. oryzae in rice  

Technology Transfer Automated Retrieval System (TEKTRAN)

The rice Xa21 gene, which confers resistance to the bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo), encodes a receptor-like kinase. Few components involved in transducing the Xa21-mediated defense response have yet been identified. It is reported that XA21 binds to a WRKY transcription fac...

195

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

PubMed

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

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

2014-11-13

196

Electrochemical biosensor for catechol using agarose-guar gum entrapped tyrosinase.  

PubMed

An electrochemical biosensor using tyrosinase was constructed for the determination of catechol. The enzyme was extracted from a plant source Amorphophallus companulatus and entrapped in agarose-guar gum composite biopolymer matrix. Catechol was determined by direct reduction of biocatalytically liberated quinone species at -0.1 V versus Ag/AgCl (3M KCl). The response was found to be linear and concentration dependent in the range of 6 x 10(-5) to 8 x 10(-4)M with a lower detection limit of 6 microM. It has reusability up to 20 cycles and a shelf life of more than 2 months when stored at 4 degrees C. PMID:17113674

Tembe, Sanket; Inamdar, Shaukat; Haram, Santosh; Karve, Meena; D'Souza, S F

2007-01-30

197

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

198

Generation of surface-confined catechol terminated SAMs via electrochemically triggered Michael addition: characterization, electrochemistry and complex with Ni(II) and Cu(II) cations.  

PubMed

In this paper, catechol, 1,4-dihydroxybenzene and dopamine are investigated as precursors of electrophiles for Michael addition reaction with the self-assembled monolayer (SAM) of 4-thiouracil (4-TU) via electrochemical triggering. All compounds can undergo Michael addition reaction with 4-TU; however, only catechol can react with 4-TU with high efficiency. The catechol-terminated SAMs, via electrochemically triggered Michael addition reaction, exhibit reversible redox response. In addition, we find that catechol-terminated SAMs can complex with Ni(2+) and Cu(2+) with different electrochemical behaviors. Moreover, the mechanism of complexation of Ni(2+)and Cu(2+) with catechol-terminated SAMs is also demonstrated with electrochemical and spectrometric methods. Based on the different electrochemical behaviors of Cu(2+) and Ni(2+) complex, the catechol-terminated SAMs provide a potential platform for metal ions recognition. PMID:20830428

Tian, Yuan; Ye, Siqiu; Ran, Qin; Xian, Yuezhong; Xu, Jingjing; Peng, Ru; Jin, Litong

2010-10-28

199

New synthetic catecholate-type siderophores based on amino acids and dipeptides  

Microsoft Academic Search

New analogs of bacterial siderophores with one, two or three catecholate moieties were synthesized using various mono- and diamino acid and dipetide scaffolds, respectively. In addition to 2,3-dihydroxybenzoyl siderophore analogs and their acylated derivatives, 3,4-dihydroxybenzoyl derivatives were prepared. Furthermore, the synthesis of a new triscatecholate serving as an intimate model for enterobactin is reported. Most of the new compounds gave

Matthias Schnabelrauch; Steffen Wittmann; Kerstin Rahn; Ute Möllmann; Rolf Reissbrodt; Lothar Heinisch

2000-01-01

200

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

201

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

202

Gender Effect of Catechol-O-Methyltransferase Val158Met Polymorphism on Suicidal Behavior  

Microsoft Academic Search

Genetic factors and catecholaminergic dysfunction have been suggested as the etiology of suicide. The catechol-O-methyltransferase (COMT) 158Val\\/Met polymorphism affects COMT activity; that is, the alleles encoding Val and Met are associated with relatively high and relatively low COMT activity, respectively. We aimed to identify the role of the COMT Val158Met polymorphism in suicidal attempt behavior. The COMT 158Val\\/Met polymorphisms were

Hwa-Young Lee; Yong-Ku Kim

2011-01-01

203

Association between Catechol-O-Methyltransferase Functional Polymorphism and Male Suicide Completers  

Microsoft Academic Search

Suicide has been suggested to involve catecholaminergic dysfunction and to be related to genetics. Catechol-O-methyltransferase (COMT) 158Val\\/Met polymorphism (GenBank Accession No. Z26491) is a polymorphism of the gene encoding COMT, a major enzyme in catecholamine inactivation. The COMT 158Val\\/Met polymorphism affects COMT activity, that is, the alleles encoding Val and Met are associated with relatively high and relatively low COMT

Hisae Ono; Osamu Shirakawa; Hideyuki Nushida; Yasuhiro Ueno; Kiyoshi Maeda

2004-01-01

204

Catechol-estrogen modified DNA: A better antigen for cancer autoantibody  

Microsoft Academic Search

Estrogens are known mutagenic and carcinogenic risk factors. Non-enzymatic oxidation of catechol-estrogens in the presence of copper is reported to generate reactive oxygen species (ROS) that can cause DNA damage. We show that DNA modification in the presence of 4-hydroxyestradiol (4-OHE2) and copper (Cu-II) results in single and double strand breaks, base modification, hyperchromicity and change in ellipticity. Modified DNA

Wahid Ali Khan; Khursheed Alam; Moinuddin

2007-01-01

205

Catechol-O-Methyltransferase Val158Met Polymorphism in Schizophrenia: Associations with Cognitive and Motor Impairment  

Microsoft Academic Search

Cognitive and motor deficits have been proposed as markers of abnormal neurodevelopment in schizophrenia and have been associated with genetic liability. In a multicenter study involving 106 subjects, 56 with deficit schizophrenia and 50 with nondeficit schizophrenia, we tested the hypothesis that the catechol-O-methyltransferase (COMT) Val158Met polymorphism is associated with cognitive and motor deficits either in schizophrenia as a whole

Silvana Galderisi; Mario Maj; Brian Kirkpatrick; Paola Piccardi; Armida Mucci; Giordano Invernizzi; Alessandro Rossi; Stefano Pini; Antonio Vita; Paolo Cassano; Paolo Stratta; Giovanni Severino; Maria Del Zompo

2005-01-01

206

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. PMID:23437082

Zhou, Ming-guo

2013-01-01

207

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

PubMed

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

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

2014-10-01

208

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

PubMed

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

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

2014-07-01

209

Iron traffics in circulation bound to a siderocalin (Ngal)-catechol complex.  

PubMed

The lipocalins are secreted proteins that bind small organic molecules. Scn-Ngal (also known as neutrophil gelatinase associated lipocalin, siderocalin, lipocalin 2) sequesters bacterial iron chelators, called siderophores, and consequently blocks bacterial growth. However, Scn-Ngal is also prominently expressed in aseptic diseases, implying that it binds additional ligands and serves additional functions. Using chemical screens, crystallography and fluorescence methods, we report that Scn-Ngal binds iron together with a small metabolic product called catechol. The formation of the complex blocked the reactivity of iron and permitted its transport once introduced into circulation in vivo. Scn-Ngal then recycled its iron in endosomes by a pH-sensitive mechanism. As catechols derive from bacterial and mammalian metabolism of dietary compounds, the Scn-Ngal-catechol-Fe(III) complex represents an unforeseen microbial-host interaction, which mimics Scn-Ngal-siderophore interactions but instead traffics iron in aseptic tissues. These results identify an endogenous siderophore, which may link the disparate roles of Scn-Ngal in different diseases. PMID:20581821

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

2010-08-01

210

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

211

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

212

Kinetics and inhibition studies of catechol O-methyltransferase from the yeast Candida tropicalis.  

PubMed Central

The Kms for esculetin and S-adenosyl-L-methionine for catechol O-methyltransferase from the yeast Candida tropicalis were 6.2 and 40 microM, respectively. S-Adenosyl-L-homocysteine was a very potent competitive inhibitor with respect to S-adenosyl-L-methionine, with a Ki of 6.9 microM. Of the catechol-related inhibitors, purpurogallin, with a Ki of 0.07 microM, showed the greatest inhibitory effect. Sulfhydryl group-blocking reagents, such as thiol-oxidizing 2-iodosobenzoic acid and mercaptide-forming p-chloromercuribenzoic acid, provided evidence for sulfhydryl groups in the active site of the enzyme. Yeast catechol O-methyltransferase is a metal-dependent enzyme and requires Mg2+ for full activity. Zn2+ and Mn2+ but not Ca2+ were able to substitute for Mg2+. Mn2+ showed optimal enzyme activation at concentrations 50- to 100-fold lower than those of Mg2+. PMID:3611026

Veser, J

1987-01-01

213

Differential gene expression in response to phenol and catechol reveals different metabolic activities for the degradation of aromatic compounds in Bacillus subtilis.  

PubMed

Aromatic organic compounds that are present in the environment can have toxic effects or provide carbon sources for bacteria. We report here the global response of Bacillus subtilis 168 to phenol and catechol using proteome and transcriptome analyses. Phenol induced the HrcA, sigmaB and CtsR heat-shock regulons as well as the Spx disulfide stress regulon. Catechol caused the activation of the HrcA and CtsR heat-shock regulons and a thiol-specific oxidative stress response involving the Spx, PerR and FurR regulons but no induction of the sigmaB regulon. The most surprising result was that several catabolite-controlled genes are derepressed by catechol, even if glucose is taken up under these conditions. This derepression of the carbon catabolite control was dependent on the glucose concentration in the medium, as glucose excess increased the derepression of the CcpA-dependent lichenin utilization licBCAH operon and the ribose metabolism rbsRKDACB operon by catechol. Growth and viability experiments with catechol as sole carbon source suggested that B. subtilis is not able to utilize catechol as a carbon-energy source. In addition, the microarray results revealed the very strong induction of the yfiDE operon by catechol of which the yfiE gene shares similarities to glyoxalases/bleomycin resistance proteins/extradiol dioxygenases. Using recombinant His6-YfiE(Bs) we demonstrate that YfiE shows catechol-2,3-dioxygenase activity in the presence of catechol as the metabolite 2-hydroxymuconic semialdehyde was measured. Furthermore, both genes of the yfiDE operon are essential for the growth and viability of B. subtilis in the presence of catechol. Thus, our studies revealed that the catechol-2,3-dioxygenase YfiE is the key enzyme of a meta cleavage pathway in B. subtilis involved in the catabolism of catechol. PMID:16872404

Tam, Le Thi; Eymann, Christine; Albrecht, Dirk; Sietmann, Rabea; Schauer, Frieder; Hecker, Michael; Antelmann, Haike

2006-08-01

214

Localizing NADPH Oxidase-Derived ROS  

NSDL National Science Digital Library

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

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

2006-08-22

215

Comparative Analysis of Aspergillus oryzae with Normal and Abnormal Color Conidia.  

PubMed

This study focuses on the characteristic of strains with anomalous color conidium and compares with normal color conidium. Comparative analysis of enzymes activity and extracellular proteins revealed that A. oryzae with anomalous color conidium was not different from the strain with normal color conidium. In addition, A. oryzae with anomalous color conidium could not influence the palatability and quality of the soy sauce. These findings provide an insight into A. oryzae with anomalous color conidium. PMID:24426175

Ye, Mao; Lin, Ying; Huang, Wenbiao; Wei, Jinhua

2014-03-01

216

p-Quinone methides are the major decomposition products of catechol estrogen o-quinones.  

PubMed

The mechanism of catechol estrogen-induced carcinogenesis could involve alkylation of critical cellular macromolecules by electrophilic quinoids. The o-quinones formed from peroxidase/P450-catalyzed oxidation of catechol estrogens have previously been implicated as the ultimate carcinogens. In the present study, we have shown that additional reactive intermediates can be produced from isomerization of the catechol estrogen o-quinones to highly electrophilic p-quinone methides (QMs). The o-quinones of the catechol estrogens were incubated at 37 degrees C (pH 7.4) in the absence of GSH. Aliquots were removed at various times and combined with GSH. The GSH adducts were isolated and characterized by 1H-NMR, UV, and electrospray mass spectrometry. The o-quinone of 2-hydroxyestrone isomerized to two QMs; a QM stabilized by one alkyl substituent in the B ring, 2-OHE-QM1 (3-hydroxy-1-(10),3(4),5(6)-oestratrien-2,17-dione) and one having two alkyl substituents on the methylene group in the C ring, 2-OHE-QM2 (2-hydroxy-1(2),4(5),9(10)-oestratrien-3,17-dione). Only one QM was observed from the o-quinone of 4-hydroxyestrone, 4-OHE-QM2 (4-hydroxy-1(2),4(5),9(10)- oestratrien-3,17-dione) which is analogous to the C ring analog (2-OHE-QM2) from the o-quinone of 2-hydroxyestrone. The GSH adduct of 4-OHE-QM2 decomposed at pH 7.4 to give 9(11)-dehydro-4-hydroxyestrone as the major product. Finally, the disappearance of the estrogen o-quinone GSH adducts correlated with the formation of the GSH conjugates of the QMs. These data suggest that in cells with low levels of GSH, the formation of these potent electrophiles represents the major reaction pathway for estrogen o-quinones. The implications of the o-quinone/QM pathway for the in vivo effects of catechol estrogens are not known; however, given the direct link between excessive exposure to endogenous estrogens and the enhanced risk of breast cancer, the potential for formation of additional reactive intermediates needs to be explored. PMID:8640939

Bolton, J L; Shen, L

1996-05-01

217

Mechanistic and structural studies of nitroalkane oxidase from Fusarium oxysporum  

E-print Network

This thesis describes the purification and the initial mechanistic studies of nitroalkane oxidase from Fusarium oxysponim. Nitroalkane oxidase catalyzes the oxidative denitrification of a nitroalkane to the corresponding aidehyde or ketone...

Heasley, Carl J

1995-01-01

218

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

PubMed

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

Z?otek, Urszula; Gawlik-Dziki, Urszula

2015-02-01

219

Microtubule reorganization during pollen development of rice ( Oryza sativa L.)  

Microsoft Academic Search

Summary Anthers of rice (Oryza sativa L.) at different stages of development were cryofixed, freeze-substituted, and embedded in methacrylate. Sections were then cut and immuno-labeled with anti-tubulin to localize microspore microtubules. Changes in microtubule distribution pattern were followed by confocal fluorescence microscopy. To facilitate description, pollen development has been divided into four developmental stages (twenty-four phases). (i) The young-microspore stage

S. Y. Zee; X. L. Ye

2000-01-01

220

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

221

Jewelry boxes contaminated by Aspergillus oryzae: an occupational health risk?  

PubMed

In 2009, 100,000 jewelry boxes, manufactured in China, were delivered to a jewelry manufacturer in Besançon, France. All the boxes were contaminated by mold. Because the workers refused to handle these jewelry boxes, the company contacted our laboratory to determine how to deal with the problem. Three choices were available: (1) decontaminate the boxes, (2) return the boxes to the Chinese manufacturer, or (3) destroy the entire shipment. Based on microscopic identification, the culture analysis was positive for A. oryzae. This could not be confirmed by molecular techniques because of the genetic proximity of A. oryzae and A. flavus. Because A. flavus can produce aflatoxins, we tested for them using mass spectrometry. Aflatoxins B1, B2, G1, G2, and M1 were not detected; however, given the specifics of this situation, we could not discard the possibility of the presence of other aflatoxins, such as P1, B3, GM2, and ethoxyaflatoxin B2. We concluded that the contamination by A. oryzae was probably due to food products. However, because of the possible presence of aflatoxins, occupational health risks could not be entirely ruled out. The decision was therefore taken to destroy all the jewelry boxes by incineration. To avoid a similar situation we propose: (1) to maintain conditions limiting mold contamination during production (not eating on the work site, efficient ventilation systems); (2) to desiccate the products before sending them; and (3) to closely control the levels of dampness during storage and transport. PMID:22702230

Bellanger, Anne-Pauline; Roussel, Anaďs; Millon, Laurence; Delaforge, Marcel; Reboux, Gabriel

2012-01-01

222

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

223

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

224

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

225

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

226

A mutation in the aroE gene affects pigment production, virulence, and chemotaxis in Xanthomonas oryzae pv. oryzae.  

PubMed

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight (BB) in rice. To study its function, a random insertion mutation library of Xoo was constructed using the Tn5 transposon. A mutant strain with decreased virulence against the susceptible rice cultivar IR24 was isolated from the library (aroE mutant), which also had extremely low pigment production. Thermal asymmetric interlaced-polymerase chain reaction (TAIL-PCR) and sequence analysis of the mutant revealed that the transposon was inserted into the aroE gene (encoding shikimate dehydrogenase). To investigate gene expression changes in the pigment- and virulence-deficient mutant, DNA microarray analysis was performed, which showed downregulation of 20 genes involved in the chemotaxis of Xoo. Our findings reveal that mutation of the aroE gene affects virulence and pigment production, as well as expression of genes involved in Xoo chemotaxis. PMID:25213405

Kim, Hong-Il; Noh, Tae-Hwan; Lee, Chang-Soo; Park, Young-Jin

2015-01-01

227

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

Microsoft Academic Search

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

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

2011-01-01

228

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

Microsoft Academic Search

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

Georgios I. Panoutsopoulos; Christine Beedham

2004-01-01

229

Relationship between Disease Resistance and Rice Oxalate Oxidases in Transgenic Rice  

PubMed Central

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

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

2013-01-01

230

Relationship between disease resistance and rice oxalate oxidases in transgenic rice.  

PubMed

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

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

2013-01-01

231

Characterization of Rice NADPH Oxidase Genes and Their Expression under Various Environmental Conditions  

PubMed Central

Plasma membrane NADPH oxidases (Noxs) are key producers of reactive oxygen species under both normal and stress conditions in plants. We demonstrate that at least eleven genes in the genome of rice (Oryza sativa L.) were predicted to encode Nox proteins, including nine genes (OsNox1–9) that encode typical Noxs and two that encode ancient Nox forms (ferric reduction oxidase 1 and 7, OsFRO1 and OsFRO7). Phylogenetic analysis divided the Noxs from nine plant species into six subfamilies, with rice Nox genes distributed among subfamilies I to V. Gene expression analysis using semi-quantitative RT-PCR and real-time qRT-PCR indicated that the expression of rice Nox genes depends on organs and environmental conditions. Exogenous calcium strongly stimulated the expression of OsNox3, OsNox5, OsNox7, and OsNox8, but depressed the expression of OsFRO1. Drought stress substantially upregulated the expression of OsNox1–3, OsNox5, OsNox9, and OsFRO1, but downregulated OsNox6. High temperature upregulated OsNox5–9, but significantly downregulated OsNox1–3 and OsFRO1. NaCl treatment increased the expression of OsNox2, OsNox8, OsFRO1, and OsFRO7, but decreased that of OsNox1, OsNox3, OsNox5, and OsNox6. These results suggest that the expression profiles of rice Nox genes have unique stress-response characteristics, reflecting their related but distinct functions in response to different environmental stresses. PMID:23629674

Wang, Gang-Feng; Li, Wen-Qiang; Li, Wen-Yan; Wu, Guo-Li; Zhou, Cong-Yi; Chen, Kun-Ming

2013-01-01

232

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

233

Development of analytical method for catechol compounds in mouse urine using hydrophilic interaction liquid chromatography with fluorescence detection.  

PubMed

An analytical method for catecholamines and related compounds using hydrophilic interaction liquid chromatography (HILIC) with native fluorescence detection has been developed. We found that ZIC-cHILIC with phosphorylcholine was suitable for the separation of catechol compounds with good peak shapes among six different HILIC columns (Inertsil SIL, Inertsil Amide, Inertsil Diol, TSKgel NH2-100, ZIC-HILIC, and ZIC-cHILIC). Using ZIC-cHILIC, eight catechol compounds (dopamine, epinephrine, norepinephrine, 3,4-dihydroxyphenylalanine, 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxyphenylglycol, 3,4-dihydroxymandelic acid, and internal standard 3,4-dihydroxybenzylamine) were separated within 15min. The limit of detection at a signal to noise ratio of 3 was 3-28nM. An improved sensitivity was obtained as compared to that of reversed-phase liquid chromatography. This was partly attributed to the increase in the fluorescence intensity of the catechol compounds in the acetonitrile-rich mobile phase. Solid phase extraction using a monolithic silica disk-packed spin column with phenylboronate moieties, which have affinity to catechol compounds, was performed for the selective extraction of catechol compounds from mouse urine. Dopamine, epinephrine, norepinephrine, 3,4-dihydroxyphenylalanine, and 3,4-dihydroxyphenylglycol were successfully quantified in mouse urine. PMID:25682335

Kanamori, Takahiro; Isokawa, Muneki; Funatsu, Takashi; Tsunoda, Makoto

2015-03-15

234

Polyphenol oxidase activity in annual forage clovers  

Technology Transfer Automated Retrieval System (TEKTRAN)

Polyphenol oxidase (PPO)-mediated phenol reactions in red clover (Trifolium pratense L.) bind forage protein and reduce proteolysis, producing beneficial effects on forage protein degradability, silage fermentation, and soil-N cycling. We evaluated PPO activity in seven previously untested annual c...

235

Studies on the mechanism of alcohol oxidase  

E-print Network

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

Menon, Vipin

1994-01-01

236

Kinetic design of the respiratory oxidases.  

PubMed

Energy conservation in all kingdoms of life involves electron transfer, through a number of membrane-bound proteins, associated with proton transfer across the membrane. In aerobic organisms, the last component of this electron-transfer chain is a respiratory heme-copper oxidase that catalyzes reduction of O(2) to H(2)O, linking this process to transmembrane proton pumping. So far, the molecular mechanism of proton pumping is not known for any system that is driven by electron transfer. Here, we show that this problem can be addressed and elucidated in a unique cytochrome c oxidase (cytochrome ba(3)) from a thermophilic bacterium, Thermus thermophilus. The results show that in this oxidase the electron- and proton-transfer reactions are orchestrated in time such that previously unresolved proton-transfer reactions could be directly observed. On the basis of these data we propose that loading of the proton pump occurs upon electron transfer, but before substrate proton transfer, to the catalytic site. Furthermore, the results suggest that the pump site alternates between a protonated and deprotonated state for every second electron transferred to the catalytic site, which would explain the noninteger pumping stoichiometry (0.5 H(+)/e(-)) of the ba(3) oxidase. Our studies of this variant of Nature's palette of mechanistic solutions to a basic problem offer a route toward understanding energy conservation in biological systems. PMID:21690359

von Ballmoos, Christoph; Gennis, Robert B; Ädelroth, Pia; Brzezinski, Peter

2011-07-01

237

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. PMID:20724480

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

2010-01-01

238

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

Microsoft Academic Search

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

Masaki Tanaka; Hitoshi Nakayashiki; Yukio Tosa

2009-01-01

239

Under pressure: investigating the biology of plant infection by Magnaporthe oryzae  

Microsoft Academic Search

The filamentous fungus Magnaporthe oryzae causes rice blast, the most serious disease of cultivated rice. Cellular differentiation of M. oryzae forms an infection structure called the appressorium, which generates enormous cellular turgor that is sufficient to rupture the plant cuticle. Here, we show how functional genomics approaches are providing new insight into the genetic control of plant infection by M.

Richard A. Wilson; Nicholas J. Talbot

2009-01-01

240

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

Microsoft Academic Search

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

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

1992-01-01

241

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

242

Biocontrol of Acanthoscelides obtectus and Sitophilus oryzae with diatomaceous earth and Beauveria bassiana on stored grains  

Microsoft Academic Search

Combined treatment with Beauveria bassiana, and diatomaceous earth (DE) was evaluated against the bean weevil Acanthoscelides obtectus and rice weevil Sitophilus oryzae. DE from Argentina was screened both alone or in combination with water or dry fungal formulations. DE killed 100% of A. obtectus and 68% of S. oryzae showing a significantly higher insecticidal effect than the fungal dust. For

G Dal Bello; S Padín; P Juárez; N Pedrini; M De Giusto

2006-01-01

243

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

244

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

245

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

246

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

247

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

248

Oryza rufipogon as a source of yield improvement in cultivated rice  

Technology Transfer Automated Retrieval System (TEKTRAN)

Oryza rufipogon is a wild relative of the cultivated species, Oryza sativa, and has been found to possess genes associated with yield improvement and resistance to biotic and abiotic stresses. We have been exploring the use of O. rufipogon as a genetic resource for yield improvement in the USA rice ...

249

Photosynthetic Bradyrhizobia Are Natural Endophytes of the African Wild Rice Oryza breviligulata  

Microsoft Academic Search

We investigated the presence of endophytic rhizobia within the roots of the wetland wild rice Oryza brevil- igulata, which is the ancestor of the African cultivated rice Oryza glaberrima. This primitive rice species grows in the same wetland sites as Aeschynomene sensitiva, an aquatic stem-nodulated legume associated with photo- synthetic strains of Bradyrhizobium. Twenty endophytic and aquatic isolates were obtained

CLEMENCE CHAINTREUIL; ERIC GIRAUD; YVES PRIN; JEAN LORQUIN; AMADOU BA; MONIQUE GILLIS; PHILIPPE DE LAJUDIE; BERNARD DREYFUS

2000-01-01

250

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

PubMed Central

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

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

2014-01-01

251

Mass spectrometric analysis of catechol-histidine adducts from insect cuticle.  

PubMed

Adducts of catechols and histidine, which are produced by reactions of 1,2-quinones and p-quinone methides with histidyl residues in proteins incorporated into the insect exoskeleton, were characterized using electrospray ionization mass spectrometry (ESMS), tandem electrospray mass spectrometry (ESMS-MS, collision-induced dissociation), and ion trap mass spectrometry (ITMS). Compounds examined included adducts obtained from acid hydrolysates of Manduca sexta (tobacco hornworm) pupal cuticle exuviae and products obtained from model reactions under defined conditions. The ESMS and ITMS spectra of 6-(N-3')-histidyldopamine [6-(N-3')-His-DA, pi isomer] isolated from M. sexta cuticle were dominated by a [M + H]+ ion at m/z 308, rather than the expected m/z 307. High-resolution fast atom bombardment MS yielded an empirical formula of C14H18N3O5, which was consistent with this compound being 6-(N-1')-histidyl-2-(3, 4-dihydroxyphenyl)ethanol [6-(N-1')-His-DOPET] instead of a DA adduct. Similar results were obtained when histidyl-catechol compounds linked at C-7 of the catechol were examined; the (N-1') isomer was confirmed as a DA adduct, and the (N-3') isomer identified as an (N-1')-DOPET derivative. Direct MS analysis of unfractionated cuticle hydrolysate revealed intense parent and product ions characteristic of 6- and 7-linked adducts of histidine and DOPET. Mass spectrometric analysis of model adducts synthesized by electrochemical oxidative coupling of N-acetyldopamine (NADA) quinone and N-acetylhistidine (NAcH) identified the point of attachment in the two isomers. A prominent product ion corresponding to loss of CO2 from [M + H]+ of 2-NAcH-NADA confirmed this as being the (N-3') isomer. Loss of (H2O + CO) from 6-NAcH-NADA suggested that this adduct was the (N-1') isomer. The results support the hypothesis that insect cuticle sclerotization involves the formation of C-N cross-links between histidine residues in cuticular proteins, and both ring and side-chain carbons of three catechols: NADA, N-beta-alanyldopamine, and DOPET. PMID:10075812

Kerwin, J L; Turecek, F; Xu, R; Kramer, K J; Hopkins, T L; Gatlin, C L; Yates, J R

1999-03-15

252

Extradiol cleavage of 3-substituted catechols by an intradiol dioxygenase, pyrocatechase, from a Pseudomonad.  

PubMed

Pyrocatechase (catechol 1,2-oxidoreductase (decyclizing), EC 1.13.11.1), a ferric ion-containing dioxygenase from Pseudomonas arvilla C-1, catalyzes the intradiol cleavage of catechol with insertion of 2 atoms of molecular oxygen to form cis,cis-muconic acid. The enzyme also catalyzed the oxidation of various catechol derivatives, including 4-methylcatechol, 4-chlorocatechol, 4-formylcatechol (protocatechualdehyde), 4,5-dichlorocatechol, 3,5-dichlorocatechol, 3-methylcatechol, 3-methoxycatechol, and 3-hydroxycatechol (pyrogallol). All of these substrates gave products having an absorption maximum at around 260 nm, which is characteristic of cis,cis-muconic acid derivatives. However, when 3-methylcatechol was used as substrate, the product formed showed two absorption maxima at 390 and 260 nm. These two absorption maxima were found to be attributable to two different products, 2-hydroxy-6-oxo-2,4-heptadienoic acid and 5-carboxy-2-methyl-2,4-pentadienoic acid (2-methylmuconic acid). The former was produced by the extradiol cleavage between the carbon atom carrying the hydroxyl group and the carbon atom carrying the hydroxyl group and the carbon atom carrying the methyl group; the latter by an intradiol cleavage between two hydroxyl groups. Since these products were unstable, they were converted to and identified as 6-methylpyridine-2-carboxylic acid and 2-methylmuconic acid dimethylester, respectively. Similarly, 3-methoxycatechol gave two products, namely, 2-hydroxy-5-methoxycarbonyl-2,4-pentadienoic acid and 5-carboxy-2-methoxy-2,4-pentadienoic acid (2-methoxymuconic acid). With 3-methylcatechol as substrate, the ratio of intradiol and extradiol cleavage activities of Pseudomonas pyrocatechase during purification was almost constant and was about 17. The final preparation of the enzyme was homogeneous when examined by disc gel electrophoresis and catalyzed both reactions simultaneously with the same ratio as during purification. All attempts to resolve the enzyme into two components with separate activities, including inactivation of the enzyme with urea or heat, treatment with sulfhydryl-blocking reagents or chelating agents, and inhibition of the enzyme with various inhibitors, proved unsuccessful. These results strongly suggest that Pseudomonas pyrocatechase is a single enzyme, which catalyzes simultaneously both intradiol and extradiol cleavages of some 3-substituted catechols. PMID:238971

Fujiwara, M; Golovleva, L A; Saeki, Y; Nozaki, M; Hayaishi, O

1975-07-10

253

Catechol Redox Induced Formation of Metal Core-Polymer Shell Nanoparticles  

PubMed Central

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

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

2011-01-01

254

Catechol O-methyltransferase. 8. Structure-activity relationships for inhibtion by 8-hydroxyquinolines.  

PubMed

A series of 5- and 7-substituted 8-hydroxyquinolines was evaluated as inhibitors of catechol O-methyltransferase (COMT, E.C. 2.1.1.6). The electronic character of the substituents in the 5 position appeared to have only a small effect if any on the inhibitory activity of these compounds. A significant factor which contributes to the inhibitory activity of these compounds appears to be the nature of the 7-substituent. The structure-activity relationship for this series of inhibitors is discussed relative to the nature of the enzymatic binding site. PMID:817025

Borchardt, R T; Thakker, D R; Warner, V D; Mirth, D B; Sane, J N

1976-04-01

255

In vitro antibacterial activity of sphaeropsidins and chemical derivatives toward Xanthomonas oryzae pv. oryzae, the causal agent of rice bacterial blight.  

PubMed

Sphaeropsidin A, the main phytotoxin produced by Diplodia cupressi, as well as the two natural analogues sphaeropsidins B and C and 14 derivatives obtained by chemical modifications were assayed for antibacterial activity against Xanthomonas oryzae pv. oryzae, Pseudomonas fuscovaginae, and Burkholderia glumae, the causal agents of severe bacterial rice diseases. The results showed a strong and specific activity of sphaeropsidin A against X. oryzae pv. oryzae, while no activity was observed against the other two pathogens. The results of structure-activity relationship studies showed that structural features important to impart this antibacterial activity are the presence of the C-7 carbonyl group and the hemiketalic lactone functionality. The C-13 vinyl group, the double bond of ring C, and/or the tertiary C-9 hydroxy group, as well as the pimarane arrangement of the tricylic carbon skeleton, were also important for the antibacterial activity. These findings may be useful in designing novel compounds for practical applications in agriculture. PMID:22124378

Evidente, Antonio; Venturi, Vittorio; Masi, Marco; Degrassi, Giuliano; Cimmino, Alessio; Maddau, Lucia; Andolfi, Anna

2011-12-27

256

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. 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

257

Mapping quantitative trait loci for yield, yield components and morphological traits in an advanced backcross population between Oryza rufipogon and the Oryza sativa cultivar Jefferson  

Microsoft Academic Search

An advanced backcross population between an accession of Oryza rufipogon (IRGC 105491) and the U.S. cultivar Jefferson ( Oryza sativa ssp. japonica) was developed to identify quantitative trait loci (QTLs) for yield, yield components and morphological traits. The genetic linkage map generated for this population consisted of 153 SSR and RFLP markers with an average interval size of 10.3 cM. Thirteen

M. J. Thomson; T. H. Tai; A. M. McClung; X. H. Lai; M. E. Hinga; K. B. Lobos; Y. Xu; C. P. Martinez; S. R. McCouch

2003-01-01

258

Quantitative trait loci for yield and yield components in an Oryza sativa×Oryza rufipogon BC2F2 population evaluated in an upland environment  

Microsoft Academic Search

An advanced backcross breeding strategy was used to identify quantitative trait loci (QTLs) associated with eight agronomic\\u000a traits in a BC2F2 population derived from an interspecific cross between Caiapo, an upland Oryza sativa subsp. japonica rice variety from Brazil, and an accession of Oryza rufipogon from Malaysia. Caiapo is one of the most-widely grown dryland cultivars in Latin America and

P. Moncada; C. P. Martínez; J. Borrero; M. Chatel; H. Gauch Jr; E. Guimaraes; J. Tohme; S. R. McCouch

2001-01-01

259

Chloroplast DNA diversity in wild and cultivated species of rice (Genus Oryza , section Oryza). Cladistic-mutation and genetic-distance analysis  

Microsoft Academic Search

Using a novel nonaqueous procedure, chloroplast DNA was isolated from 318 individual adult rice plants, representing 247 accessions and the breadth of the diversity in section Oryza of genus Oryza. Among them, 32 different cpDNA restriction patterns were distinguished using the restriction endonucleases EcoRI and AvaI, and they were further characterized by restriction with BamHI, HindIII, SmaI, PstI, and BstEII

A. M. Dally; G. Second

1990-01-01

260

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

PubMed Central

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

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

2012-01-01

261

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

PubMed

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

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

2013-01-01

262

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

PubMed Central

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

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

2013-01-01

263

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

Microsoft Academic Search

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

Farukh Arjmand; Shamima Parveen; Sartaj Tabassum

2005-01-01

264

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

Microsoft Academic Search

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

Ruchi Bakshi; Miriam Rossi; Francesco Caruso; Pavan Mathur

2011-01-01

265

Lysyl oxidase expression and inhibition in uveal melanoma.  

PubMed

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

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

2010-04-01

266

Human catechol-O-methyltransferase: Cloning and expression of the membrane-associated form  

SciTech Connect

A cDNA clone for human catechol-O-methyltransferase was isolated from a human hepatoma cell line (Hep G2) cDNA library by hybridization screening with a porcine cDNA probe. The cDNA clone was sequenced and found to have an insert of 1226 nucleotides. The deduced primary structure of hCOMT is composed of 271 amino acid residues with the predicted molecular mass of 30 kDa. At its N terminus it has a hydrophobic segment of 21 amino acid residues that may be responsible for insertion of hCOMT into the endoplasmic reticulum membrane. The primary structure of hCOMT exhibits high homology to the porcine partial cDNA sequence (93%). The deduced amino acid sequence contains two tryptic peptide sequences (T-22, T-33) found in porcine liver catechol-O-methyltransferase (CEMT). The coding region of hCOMT cDNA was placed under the control of the cytomegalovirus promoter to transfect human kidney 293 cells. The recombinant hCOMT was shown by immunoblot analysis to be mainly associated with the membrane fraction. RNA blot analysis revealed one COMT mRNA transcript of 1.4 kilobases in Hep G2 poly(A){sup +} RNA.

Bertocci, B.; Miggiano, V.; Da Prada, M.; Dembic, Z.; Lahm, H.W.; Malherbe, P. (F. Hoffmann-La Roche Ltd., Basel (Switzerland))

1991-02-15

267

Recovery of biological active catechol-O-methyltransferase isoforms from Q-sepharose.  

PubMed

The development of new catechol-O-methyltransferase inhibitors has led to an improvement in the treatment of Parkinson's disease. However, despite the fact that the soluble isoform has been extensively investigated, few studies have been published concerning membrane isoform chromatographic recovery and bioactivity levels. In this work, chromatographic profiles of both catechol-O-methyltransferase isoforms were compared using quaternary amine as a ligand to evaluate its activity levels and recovery rates. Results show that both proteins required different conditions for adsorption; the soluble isoform adsorption was performed at low ionic strength, while the membrane isoform required increasing linear salt gradient. However, the application of 0.5% Triton X-100 promoted membrane isoform adsorption even at low ionic strength. Indeed, chromatographic conditions of both isoforms became similar when detergents were applied. The developed methods also appear to be highly effective in bioactivity recovery, presenting rates of 107% for soluble protein and 67 and 91% for membrane isoform without and with detergents, respectively. The chromatographic strategies with and without detergents resulted in a 4.3- and sevenfold purification, respectively, corresponding to specific activity values of 331 and 496 nmol/h/mg. Thus, the use of Q-sepharose as anion exchanger was effective in the recovery of both enzymes, which is a requirement for further kinetic and pharmacological trials. PMID:24285473

Correia, F F; Santos, F M; Pedro, A Q; Bonifácio, M J; Queiroz, J A; Passarinha, L A

2014-01-01

268

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

269

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

PubMed Central

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

Xu, Zhiping

2013-01-01

270

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

PubMed Central

The inactivation of catechol 2,3-dioxygenase from Pseudomonas putida mt-2 by 3-chloro- and 3-fluorocatechol and the iron-chelating agent Tiron (catechol-3,5-disulfonate) was studied. Whereas inactivation by Tiron is an oxygen-independent and mostly reversible process, inactivation by the 3-halocatechols was only observed in the presence of oxygen and was largely irreversible. The rate constants for inactivation (K2) were 1.62 × 10?3 sec?1 for 3-chlorocatechol and 2.38 × 10?3 sec?1 for 3-fluorocatechol. The inhibitor constants (Ki) were 23 ?M for 3-chlorocatechol and 17 ?M for 3-fluorocatechol. The kinetic data for 3-fluorocatechol could only be obtained in the presence of 2-mercaptoethanol. Besides inactivated enzyme, some 2-hydroxyhexa-2,4-diendioic acid was formed from 3-chlorocatechol, suggesting 5-chloroformyl-2-hydroxypenta-2,4-dienoic acid as the actual suicide product of meta-cleavage. A side product of 3-fluorocatechol cleavage is a yellow compound with the spectral characteristics of a 2-hydroxy-6-oxohexa-2,4-dienoic acid indicating 1,6-cleavage. Rates of inactivation by 3-fluorocatechol were reduced in the presence of superoxide dismutase, catalase, formate, and mannitol, which implies that superoxide anion, hydrogen peroxide, and hydroxyl radical exhibit additional inactivation. PMID:16346490

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

1984-01-01

271

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

NASA Astrophysics Data System (ADS)

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

Xu, Zhiping

2013-10-01

272

Xanthine oxidase biosensor for monitoring meat spoilage  

NASA Astrophysics Data System (ADS)

In this study, we have designed an electrochemical biosensor for real-time detection of specific biomarkers of bacterial metabolism related to meat spoilage (hypoxanthine and xanthine). The selective biosensor was developed by assembling a `sandwich' of nanomaterials and enzymes on a platinum-iridium electrode (1.6 mm tip diameter). The materials deposited on the sensor tip include amorphous platinum nanoclusters (i.e. Pt black), reduced graphene oxide, nanoceria, and xanthine oxidase. Xanthine oxidase was encapsulated in laponite hydrogel and used for the biorecognition of hypoxanthine and xanthine (two molecules involved in the rotting of meat by spoilage microorganisms). The developed biosensor demonstrated good electrochemical performance toward xanthine with sensitivity of 2.14 +/- 1.48 ?A/mM, response time of 5.2 +/- 1.5 sec, lower detection limit of 150 +/- 39 nM, and retained at least 88% of its activity after 7 days of continuous use.

Vanegas, D. C.; Gomes, C.; McLamore, E. S.

2014-05-01

273

Imaging Monoamine Oxidase in the Human Brain  

SciTech Connect

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

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

1999-11-10

274

Defensive Roles of Polyphenol Oxidase in Plants  

Microsoft Academic Search

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

C. Peter Constabel; Raymond Barbehenn

275

Comparison of kinetic properties of amine oxidases from sainfoin and lentil and immunochemical characterization of copper/quinoprotein amine oxidases.  

PubMed

Kinetic properties of novel amine oxidase isolated from sainfoin (Onobrychis viciifolia) were compared to those of typical plant amine oxidase (EC 1.4.3.6) from lentil (Lens culinaris). The amine oxidase from sainfoin was active toward substrates, such as 1,5-diaminopentane (cadaverine) with K(m) of 0.09 mM and 1,4-diaminobutane (putrescine) with K(m) of 0.24 mM. The maximum rate of oxidation for cadaverine at saturating concentration was 2.7 fold higher than that of putrescine. The amine oxidase from lentil had the maximum rate for putrescine comparable to the rate of sainfoin amine oxidase with the same substrate. Both amine oxidases, like other plant Cu-amine oxidases, were inhibited by substrate analogs (1,5-diamino-3-pentanone, 1,4-diamino-2-butanone and aminoguanidine), Cu2+ chelating agents (diethyltriamine, 1,10-phenanthroline, 8-hydroxyquinoline, 2,2'-bipyridyl, imidazole, sodium cyanide and sodium azide), some alkaloids (L-lobeline and cinchonine), some lathyrogens (beta-aminopropionitrile and aminoacetonitrile) and other inhibitors (benzamide oxime, acetone oxime, hydroxylamine and pargyline). Tested by Ouchterlony's double diffusion in agarose gel, polyclonal antibodies against the amine oxidase from sainfoin, pea and grass pea cross-reacted with amine oxidases from several other Fabaceae and from barley (Hordeum vulgare) of Poaceae, while amine oxidase from the filamentous fungus Aspergillus niger did not cross-react at all. However, using Western blotting after SDS-PAGE with rabbit polyclonal antibodies against the amine oxidase from Aspergillus niger, some degree of similarity of plant amine oxidases from sainfoin, pea, field pea, grass pea, fenugreek, common melilot, white sweetclover and Vicia panonica with the A. niger amine oxidase was confirmed. PMID:10092944

Zajoncová, L; Frébort, I; Luhová, L; Sebela, M; Galuszka, P; Pec, P

1999-01-01

276

Kinetic studies of Rhizopus oryzae lipase using monomolecular film technique.  

PubMed

Rhizopus oryzae lipase (ROL) was found to be a true lipase. This enzyme presents the interfacial activation phenomenon. The N-terminal amino acid sequence of ROL was compared to those of rhizopus lipases. Purified ROL possesses the same N-terminal sequence as the mature Rhizopus niveus lipase (RNL). This sequence was found in the last 28 amino acids of the propeptide sequence derived from the cDNA of Rhizopus delemar lipase (RDL). Using the baro-stat method, we have measured the hydrolysis rate of dicaprin films by ROL as a function of surface pressure. Our results show that Rhizopus oryzae lipase is markedly stereoselective of the sn-3 position of the 2,3 enantiomer of dicaprin. Polyclonal antibodies (PAB) directed against ROL have been produced and purified by immunoaffinity. The effects of these PAB on the interfacial behavior of ROL were determined. The immunoblot analysis with polyclonal antibodies anti-ROL (PAB anti-ROL) and various lipases shows a cross-immunoreactivity between the lipase from the rhizopus family (Rhizopus delemar lipase and Rhizopus arrhizus lipase). PMID:11506890

Ben Salah, A; Sayari, A; Verger, R; Gargouri, Y

2001-06-01

277

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

278

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

Microsoft Academic Search

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

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

2012-01-01

279

Altering substrate specificity of catechol 2,3-dioxygenase from Planococcus sp. strain S5 by random mutagenesis.  

PubMed

c23o gene, encoding catechol 2,3-dioxygenase from Planococcus sp. strain S5 was randomly mutagenized to generate variant forms of the enzyme with higher degradation activity. Additionally, the effect of introduced mutations on the enzyme structure was analyzed based on the putative 3D models the wild-type and mutant enzymes. C23OB58 and C23OB81 mutant proteins with amino acid substitutions in close proximity to the enzyme surface or at the interface and in the vicinity of the enzyme active site respectively showed the lowest activity towards all catecholic substrates. The relative activity of C23OC61 mutant towards para-substituted catechols was 20-30% lower of the wild-type enzyme. In this mutant all changes: F191I, C268R, Y272H, V280A and Y293D were located within the conserved regions of C-terminal domain. From these F191I seems to have significant implications for enzyme activity. The highest activity towards different catechols was found for mutant C23OB65. R296Q mutation improved the activity of C23O especially against 4-chlorocatechol. The relative activity of above-mentioned mutant detected against this substrate was almost 6-fold higher than the wild-type enzyme. These results should facilitate future engineering of the enzyme for bioremediation. PMID:25337606

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

2014-01-01

280

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

PubMed

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

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

2013-01-01

281

Activity of a carboxyl-terminal truncated form of catechol 2,3-dioxygenase from Planococcus sp. S5.  

PubMed

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

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

2014-01-01

282

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

PubMed Central

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

2014-01-01

283

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

PubMed

Adults of the lubber grasshopper (Romalea guttata) secrete increased amounts of catechol from their defensive glands when fed diets containing only catnip leaves (Nepeta cataria). Model compound bioassays showed that these insects were able to sequester and biomagnify simple phenols, such as catechol and hydroquinone, in their defense gland secretions. Excessive catechol secretions from caffeic acid-fortified diets indicated metabolic pathways exist to perform efficiently more complex biochemical conversions. Reverse-phase HPLC of methanol extracts of catnip revealed only one major caffeoyl-polyphenol as a possible precursor for the observed elevated catechol secretions, when this plant is fed to lubbers. The compound was shown to be caffeoyltartronic acid (CTA). During analysis of CTA by probe-MS or gas chromatography (of its silylated derivative), CTA decomposed by loss of carbon dioxide to form caffeoylglycolic acid (CGA), making identification by these methods ambiguous. Only fast atom bombardment mass spectrometry (FAB-MS, negative mode) gave a true molecular weight. Groundivy (Glecoma hederacea), a relative of catnip, was also shown to contain CTA. The mung bean (Phaseolus radiatus=Vigna radiata), a species totally unrelated to catnip, is the only other reported plant source of CTA. Catnip leaves were found to contain about twice as much CTA as mung bean leaves. PMID:24249371

Snook, M E; Blum, M S; Whitman, D W; Arrendale, R F; Costello, C E; Harwood, J S

1993-09-01

284

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

285

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

Microsoft Academic Search

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

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

2006-01-01

286

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

PubMed Central

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

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

2007-01-01

287

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

E-print Network

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

McCusker, James K.

288

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...

289

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

EPA Science Inventory

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

290

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

EPA Science Inventory

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

291

Diphenyl-benzo[1,3]dioxole-4-carboxylic acid pentafluorophenyl ester: a convenient catechol precursor in the synthesis of siderophore vectors suitable for antibiotic Trojan horse strategies.  

PubMed

Catechols are components of many metal-chelating compounds, including siderophores that are naturally occurring iron(III) chelators excreted by microorganisms. Catechol derivatives are poorly soluble in organic media and the synthesis of catechol-containing molecules requires the use of protected catechol precursors with improved organic solubility. We therefore developed 2,2-diphenyl-benzo[1,3]dioxole-4-carboxylic acid pentafluorophenyl ester. This activated ester reacts with an amine functionalized scaffold to generate chelators in which the catechol functions are protected in the form of diphenyl-benzodioxole moieties. The catechol can subsequently be deprotected, at the end of the synthesis, with trifluoroacetic acid (TFA). This strategy was applied to the synthesis of two catechol compounds functionalized with a terminal propargyl extension. These two compounds were shown to promote iron uptake in Escherichia coli and Pseudomonas aeruginosa. These two compounds are suitable for use as vectors in antibiotic Trojan horse approaches, as they could be conjugated with azide-functionalized antibiotics using the Huisgen dipolar 1,3-cycloaddition. PMID:24305839

Baco, Etienne; Hoegy, Françoise; Schalk, Isabelle J; Mislin, Gaëtan L A

2014-02-01

292

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

293

Lysyl Oxidases: Expression in the Fetal Membranes and Placenta  

Microsoft Academic Search

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

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

2001-01-01

294

Purification and characterization of extracellular cholesterol oxidase from Enterobacter sp  

Microsoft Academic Search

The objective of this work is to obtain an abundant source of cholesterol oxidases for industrial and medicinal needs. Thirteen\\u000a bacterial strains that express high level of inducible extracellular cholesterol oxidase (COX) were isolated from carnivore\\u000a feces. One of these strains, named COX8-9, belonging to the genus Enterobacter, was found to produce the highest level of cholesterol oxidase. COX from

Deping Ye; Jiahong Lei; Wei Li; Fanglan Ge; Ke Wu; Wenliu Xu; Bin Yong

2008-01-01

295

Under pressure: investigating the biology of plant infection by Magnaporthe oryzae.  

PubMed

The filamentous fungus Magnaporthe oryzae causes rice blast, the most serious disease of cultivated rice. Cellular differentiation of M. oryzae forms an infection structure called the appressorium, which generates enormous cellular turgor that is sufficient to rupture the plant cuticle. Here, we show how functional genomics approaches are providing new insight into the genetic control of plant infection by M. oryzae. We also look ahead to the key questions that need to be addressed to provide a better understanding of the molecular processes that lead to plant disease and the prospects for sustainable control of rice blast. PMID:19219052

Wilson, Richard A; Talbot, Nicholas J

2009-03-01

296

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

NASA Astrophysics Data System (ADS)

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

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

2008-05-01

297

Purification and biochemical characterization of ionically unbound polyphenol oxidase from Musa paradisiaca leaf.  

PubMed

An ionically unbound and thermostable polyphenol oxidase (PPO) was extracted from the leaf of Musa paradisiaca. The enzyme was purified 2.54-fold with a total yield of 9.5% by ammonium sulfate precipitation followed by Sephadex G-100 gel filtration chromatography. The purified enzyme exhibited a clear single band on native polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate (SDS) PAGE. It was found to be monomeric protein with molecular mass of about 40 kD. The zymographic study using crude extract as enzyme source showed a very clear band around 40 kD and a faint band at around 15 kD, which might be isozymes. The enzyme was optimally active at pH 7.0 and 50°C temperature. The enzyme was active in wide range of pH (4.0-9.0) and temperature (30-90°C). From the thermal inactivation studies in the range 60-75°C, the half-life (t(1/2)) values of the enzyme ranged from 17 to 77 min. The inactivation energy (Ea) value of PPO was estimated to be 91.3 kJ mol(-1). It showed higher specificity with catechol (K(m) = 8 mM) as compared to 4-methylcatechol (K(m) = 10 mM). Among metal ions and reagents tested, Cu(2+), Fe(2+), Hg(2+), Mn(2+), Ni(2+), protocatechuic acid, and ferrulic acid enhanced the enzyme activity, while K(+), Na(+), Co(2+), kojic acid, ascorbic acid, ethylenediamine tetraacetic acid (EDTA), sodium azide, ?-mercaptoethanol, and L-cysteine inhibited the activity of the enzyme. PMID:21442554

Diwakar, Sanjeev Kumar; Mishra, Sarad Kumar

2011-01-01

298

Development of irreversible inactivators of spermine oxidase and N1-acetylpolyamine oxidase.  

PubMed

Three functional groups (2-propenyl, 2-propynyl, and 2,3-butadienyl) were introduced onto one of the terminal amino groups of spermidine. Of the six compounds synthesized, N-(3-aminopropyl)-N'-2,3-butadienyl-1,4-butanediamine (N(8)-butadienyl Spd) and N-[3-(2,3-butadienylamino)propyl]-1,4-butanediamine (N(1)-butadienyl Spd) irreversibly inactivated human spermine oxidase (SMO) and N(1)-acetylpolyamine oxidase (APAO). Interestingly, N(8)-butadienyl Spd inactivated SMO far more potently than N,N'-di-2,3-butadienyl-1,4-butanediamine (MDL 72527). PMID:24583866

Moriya, Shun-suke; Miura, Toshiyuki; Takao, Koichi; Sugita, Yoshiaki; Samejima, Keijiro; Hiramatsu, Kyoko; Kawakita, Masao

2014-01-01

299

Cell wall degrading enzyme induced rice innate immune responses are suppressed by the type 3 secretion system effectors XopN, XopQ, XopX and XopZ of Xanthomonas oryzae pv. oryzae.  

PubMed

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

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

2013-01-01

300

Targeting NADPH Oxidases for the Treatment of Cancer and Inflammation  

PubMed Central

NADPH oxidases are a family of oxidases that utilize molecular oxygen to generate hydrogen peroxide and superoxide, thus indicating physiological functions of these Highly reactive and short lived species. The regulation of these NADPH oxidases (nox) enzymes is complex, with many members of this family exhibiting complexity in subunit composition, cellular location, and tissue specific expression. While the complexity of the nox family (Nox1–5, Duox1,2) is daunting, the complexity also allows for targeting of NADPH oxidases in disease states. This review will discuss which inflammatory and malignant disorders can be targeted by nox inhibitors, as well as clinical experience in the use of nox inhibitors. PMID:22581366

Bonner, Michael Y.; Arbiser, Jack L

2015-01-01

301

21 CFR 866.2420 - Oxidase screening test for gonorrhea.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

302

21 CFR 866.2420 - Oxidase screening test for gonorrhea.  

Code of Federal Regulations, 2012 CFR

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

2012-04-01

303

21 CFR 866.2420 - Oxidase screening test for gonorrhea.  

Code of Federal Regulations, 2014 CFR

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

2014-04-01

304

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

PubMed Central

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

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

2013-01-01

305

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

PubMed Central

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

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

2013-01-01

306

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

PubMed

Rice straw is always regarded as a by-product of rice production, but it could be a significant energy source for ruminant animals. Knowledge of the genetic variation and genetic architecture of cell wall traits will facilitate rice breeders by improving relevant traits through selective breeding and genetic engineering. The common wild rice, Oryza rufipogon Griff., which is considered to be the progenitor of Oryza sativa, has been widely utilized for the identification of genes of agronomic importance for rice genetic improvement. In the present study, the mapping of quantitative trait loci (QTLs) for acid detergent fiber (ADF), neutral detergent fiber (NDF), acid detergent lignin (ADL), and ADL/NDF ratio was carried out in two environments using a backcrossed inbred line (BIL) population derived from a cross between the recurrent parent Xieqingzao B (XB) and an accession of Dongxiang wild rice (DWR). The results indicated that all four traits tested were continuously distributed among the BILs, but many BILs showed transgressive segregation. A total of 16 QTLs were identified for the four traits, but no QTLs were in common in two environments, suggesting that environment has dramatic effects on fiber and lignin syntheses. Compared to the QTL positions for grain yield-related traits, there were no unfavorable correlations between grain yield components and cell wall traits in this population. The QTLs identified in this study are useful for the development of dual-purpose rice varieties that are high in grain yield and are also high in straw quality. PMID:21726058

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

2011-07-01

307

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

308

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

PubMed Central

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

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

2014-01-01

309

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. PMID:16393141

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

2006-01-01

310

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

Microsoft Academic Search

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

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

2011-01-01

311

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

312

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

PubMed Central

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

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

2013-01-01

313

Bioactivation of estrone and its catechol metabolites to quinoid-glutathione conjugates in rat liver microsomes.  

PubMed

Although the carcinogenic effects of estrogens have been mainly attributed to hormonal properties, there is interest in estrogens acting as chemical carcinogens by binding to cellular macromolecules. In the present study, we explored factors which influence the rate of P450-catalyzed formation of the o-quinones (3,5-cyclohexadiene-1,2-diones) from 2-hydroxyestrone (2-OHE) and 4-hydroxyestrone (4-OHE) as well as from estrone in rat liver microsomes. The initially formed o-quinones were trapped as their GSH conjugates which were separated and characterized by HPLC with electrospray-MS detection. Two mono-GSH conjugates were observed from the 2-OHE-o-quinone as well as a conjugate where GSH had added twice to the molecule producing a di-GSH conjugate. 4-OHE-o-quinone gave only one mono-GSH adduct as well as a di-GSH adduct. Both 2-OHE and 4-OHE were excellent substrates for P450, generating o-quinone GSH adducts at 94 and 40 times, respectively, the rate of estrone. 2-OHE but not 4-OHE saturated P450 at unusually low concentrations (0.2 nmol of P450/mL) perhaps due to differences in the stability of the o-quinones formed in the active site of the enzyme. Preliminary data suggest that the o-quinones of both 2-OHE and 4-OHE could isomerize to quinone methides (4-alkyl-2,5-cyclohexadien-1-ones, QMs). The o-quinones of the catechol estrogens were incubated at 37 degrees C (pH 7.4) in the absence of GSH. Aliquots were removed at various times and combined with GSH. From the pseudo-first-order rate of disappearance of the o-quinone GSH adducts, the half-lives of the o-quinones were determined. The o-quinone from 2-OHE has a half-life of 42 +/- 3 s at 37 degrees C (pH 7.4), and the o-quinone from 4-OHE has a half-life of 12.2 +/- 0.4 min under identical conditions. The o-quinones of the AB ring analogs of the catechol estrogens (3,4-dihydroxy-5,6,7,8-tetrahydronaphthalene and 1,2-dihydroxy-5,6,7,8-tetrahydronaphthalene) isomerize to QMs, suggesting that a similar reaction pathway could occur with the o-quinones from catechol estrogens. In support of this, oxidation of 4-OHE and quenching with GSH after 70 min produced 9-dehydro-4-hydroxyestrone (3-hydroxy-1,3,5-(10),9(11)-estratetraen-17-one), a product which could result from either the QM hydrolysis product or the QM--glutathione conjugate, both of which could eliminate to give the conjugated alkene of 4-OHE. The implications of the o-quinone/QM pathway to the in vivo effects of catechol estrogens are not known; however, given the direct link between excessive exposure to endogenous estrogens and the enhanced risk of breast cancer, the potential for formation of additional reactive intermediates needs to be explored. PMID:8839054

Iverson, S L; Shen, L; Anlar, N; Bolton, J L

1996-03-01

314

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

315

Formation and Processing of Secondary Organic Aerosol from Catechol as a Model for Atmospheric HULIS  

NASA Astrophysics Data System (ADS)

A particular fraction of the secondary organic aerosol (SOA) termed HUmic Like Substances (HULIS) attracted attention only recently in atmospheric aerosol, initiating a discourse about their aromaticity and other properties, such as reactivity and hygroscopicity. A major portion of HULIS originates from volatile organic compounds, which are formed by abiotic oxidation reactions involving mainly OH radicals, ozone, nitrogen oxides and possibly halogens. Subsequently, the particles provide surface for heterogeneous reactions with atmospheric trace gases. Thus, aerosol smog-chamber studies with appropriate precursors are needed to generate SOA with HULIS qualities in situ inside the smog chamber and study their possible interactions. Catechol and guaiacol were chosen as aromatic precursors for synthetic HULIS production. The SOA was produced in a 700 L aerosol smog chamber, equipped with a solar simulator. SOA formation from each precursor was investigated at simulated environmental conditions (humidity, light, and presence of oxidizers) and characterized with respect to HULIS properties by particle classifiers, Fourier Transform IR spectroscopy (by long-path absorption and attenuated total reflection), UV/VIS spectroscopy, high-resolution mass-spectroscopy and temperature-programmed-desorption mass-spectrometry. High-resolution imaging was obtained using Field Emission Gun Scanning Electron Microscopy (FEGSEM). After HULIS formation the aerosol particles were exposed to atmospheric halogen species to study their processing with those trace gases, released by sea salt-activation. Those investigations show that aromatic precursors like catechol and guaiacol are suitable to form synthetic HULIS for laboratory-scale measurements with physical and chemical properties described in literature. However, sunlight and relative humidity play a major role in particle production and composition of functional groups, which are the anchor points for heterogeneous atmospheric chemistry. Possible reaction pathways of those synthetic particles with atmospheric halogen species could be identified forming gaseous and solid halogenated compounds.

Ofner, Johannes; Krüger, Heinz-Ulrich; Grothe, Hinrich; Zetzsch, Cornelius

2010-05-01

316

Exploiting algal NADPH oxidase for biophotovoltaic energy  

E-print Network

synthetic gene construct containing the complete RBO1 gene model (Table 1). Three independently transformed strains were selected by antibiotic resistance and confirmed for RBO1 by PCR (Figure 5a). These were compared for light-dependent O#1;#3;2 production... the electron transport proteins that contribute power output in the devices remains a fundamental goal in the development of these biological solar cells. Plasma membrane NADPH oxidases (NOX) are found in animals, plants and algae. They are encoded in animals...

Anderson, Alexander; Laohavisit, Anuphon; Blaby, Ian K.; Bombelli, Paolo; Howe, Christopher J.; Merchant, Sabeeha S.; Davies, Julia M.; Smith, Alison G.

2015-01-29

317

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

E-print Network

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

Scheuring, Chantel Fougeron

1987-01-01

318

Red rice (Oryza sativa L.) ecotype tolerance to herbicides and winter weed management practices  

E-print Network

(1999b), was found to be genetically similar to Oryza rufipogon accession 105491, while other red rice ecotypes were similar to Oryza sativa ssp. indica (Vaughan et al. 2001). Red rice ecotype TX4 has low susceptibility to glufosinate (Noldin 1999a... Procedure using SAS 2 software with mean separation done by Fisher?s protected LSD. Weed populations sufficient to allow evaluation included spinyfruit buttercup, RANMU (Ranunculus muricatus L.); field clover TRFCA (Trifolium campestri Schreb.); dock...

Nanson, Weldon Duane

2009-05-15

319

Lactic Acid Fermentation of Potato Pulp by the Fungus Rhizopus oryzae  

Microsoft Academic Search

Thirty-eight strains of the fungus Rhizopus oryzae were grown on potato pulp, an agricultural by-product of the starch industry. Either lactic acid or fumaric acid and ethanol\\u000a were formed, and the ratio differed among the strains tested. The highest amount of L(+)-lactic acid (10 mg\\/g fresh matter)\\u000a was observed in the pulp fermented for six days by Rhizopus oryzae IFO

Yuji Oda; Katsuichi Saito; Hiroaki Yamauchi; Motoyuki Mori

2002-01-01

320

Responses of High Biomass Rice (Oryza sativa L.) to Various Abiotic Stresses  

E-print Network

iii RESPONSES OF HIGH BIOMASS RICE (ORYZA SATIVA L.) TO VARIOUS ABIOTIC STRESSES A Thesis by ADITI NITINKUMAR KONDHIA Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE August 2010 Major Subject: Plant Breeding iv Responses of High Biomass Rice (Oryza sativa L.) to Various Abiotic Stresses Copyright 2010 Aditi...

Kondhia, Aditi Nitinkumar

2011-10-21

321

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

322

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

Microsoft Academic Search

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

Keiichi Nakajima; Motoaki Sano; Masayuki Machida

2000-01-01

323

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

Microsoft Academic Search

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

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

324

Diversity and high nitrogenase activity of endophytic diazotrophs isolated from Oryza rufipogon Griff  

Microsoft Academic Search

Diversity and nitrogenase activity of endophytic diazotrophs colonized in the wild rice Oryza rufipogon Griff grown in Boluo, Huilai County in Guangdong Province and Lingshui County in Hainan Province were studied. Thirty-seven\\u000a isolates obtained from Oryza rufipogon were identified as putative endophytic nitrogen-fixing bacteria by ARA (acetylene reduction assay) test and further confirmed\\u000a by PCR amplification of nifH gene fragments.

ZhiYuan Tan; GuiXiang Peng; PeiZhi Xu; ShaoYing Ai; ShuanHu Tang; GuoXia Zhang; FengYun Zeng

2009-01-01

325

Multicopper oxidase-1 orthologs from diverse insect species have ascorbate oxidase activity.  

PubMed

Members of the multicopper oxidase (MCO) family of enzymes can be classified by their substrate specificity; for example, ferroxidases oxidize ferrous iron, ascorbate oxidases oxidize ascorbate, and laccases oxidize aromatic substrates such as diphenols. Our previous work on an insect multicopper oxidase, MCO1, suggested that it may function as a ferroxidase. This hypothesis was based on three lines of evidence: RNAi-mediated knock down of Drosophila melanogaster MCO1 (DmMCO1) affects iron homeostasis, DmMCO1 has ferroxidase activity, and DmMCO1 has predicted iron binding residues. In our current study, we expanded our focus to include MCO1 from Anopheles gambiae, Tribolium castaneum, and Manduca sexta. We verified that MCO1 orthologs have similar expression profiles, and that the MCO1 protein is located on the basal surface of cells where it is positioned to oxidize substrates in the hemolymph. In addition, we determined that RNAi-mediated knock down of MCO1 in A. gambiae affects iron homeostasis. To further characterize the enzymatic activity of MCO1 orthologs, we purified recombinant MCO1 from all four insect species and performed kinetic analyses using ferrous iron, ascorbate and two diphenols as substrates. We found that all of the MCO1 orthologs are much better at oxidizing ascorbate than they are at oxidizing ferrous iron or diphenols. This result is surprising because ascorbate oxidases are thought to be specific to plants and fungi. An analysis of three predicted iron binding residues in DmMCO1 revealed that they are not required for ferroxidase or laccase activity, but two of the residues (His374 and Asp380) influence oxidation of ascorbate. These two residues are conserved in MCO1 orthologs from insects and crustaceans; therefore, they are likely to be important for MCO1 function. The results of this study suggest that MCO1 orthologs function as ascorbate oxidases and influence iron homeostasis through an unknown mechanism. PMID:25701385

Peng, Zeyu; Dittmer, Neal T; Lang, Minglin; Brummett, Lisa M; Braun, Caroline L; Davis, Lawrence C; Kanost, Michael R; Gorman, Maureen J

2015-04-01

326

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. PMID:24743650

He, Yuan; Hao, Qi; Li, Wenqi; Yan, Chuangye

2014-01-01

327

Genomics of Aspergillus oryzae: learning from the history of Koji mold and exploration of its future.  

PubMed

At a time when the notion of microorganisms did not exist, our ancestors empirically established methods for the production of various fermentation foods: miso (bean curd seasoning) and shoyu (soy sauce), both of which have been widely used and are essential for Japanese cooking, and sake, a magical alcoholic drink consumed at a variety of ritual occasions, are typical examples. A filamentous fungus, Aspergillus oryzae, is the key organism in the production of all these traditional foods, and its solid-state cultivation (SSC) has been confirmed to be the secret for the high productivity of secretory hydrolases vital for the fermentation process. Indeed, our genome comparison and transcriptome analysis uncovered mechanisms for effective degradation of raw materials in SSC: the extracellular hydrolase genes that have been found only in the A. oryzae genome but not in A. fumigatus are highly induced during SSC but not in liquid cultivation. Also, the temperature reduction process empirically adopted in the traditional soy-sauce fermentation processes has been found to be important to keep strong expression of the A. oryzae-specific extracellular hydrolases. One of the prominent potentials of A. oryzae is that it has been successfully applied to effective degradation of biodegradable plastic. Both cutinase, responsible for the degradation of plastic, and hydrophobin, which recruits cutinase on the hydrophobic surface to enhance degradation, have been discovered in A. oryzae. Genomic analysis in concert with traditional knowledge and technology will continue to be powerful tools in the future exploration of A. oryzae. PMID:18820080

Machida, Masayuki; Yamada, Osamu; Gomi, Katsuya

2008-08-01

328

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

PubMed

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

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

2014-11-18

329

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. PMID:20545847

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

330

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. PMID:24885968

2014-01-01

331

Rapid diversification of five Oryza AA genomes associated with rice adaptation  

PubMed Central

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

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

2014-01-01

332

Bilirubin oxidase bioelectrocatalytic cathodes: the impact of hydrogen peroxide.  

PubMed

Mediator-less, direct electro-catalytic reduction of oxygen to water by bilirubin oxidase (Myrothecium sp.) was obtained on anthracene-modified, multi-walled carbon nanotubes. H2O2 was found to significantly and irreversibly affect the electro-catalytic activity of bilirubin oxidase, whereas similar electrodes comprised of laccase (Trametes versicolor) were reversibly inhibited. PMID:24185735

Milton, Ross D; Giroud, Fabien; Thumser, Alfred E; Minteer, Shelley D; Slade, Robert C T

2014-01-01

333

Ascorbic acid and L-gulonolactone oxidase in lagomorphs.  

PubMed

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

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

1978-01-01

334

Investigation of catechol 2,3-dioxygenase and 16S rRNA gene diversity in hypoxic, petroleum hydrocarbon contaminated groundwater  

Microsoft Academic Search

Detection of catechol 2,3-dioxygenase genes in aromatic hydrocarbon contaminated environments gives the opportunity to measure the diversity of bacteria involved in the degradation of the contaminants under aerobic conditions. In this study, we investigated the diversity and distribution of Comamonadaceae family (Betaproteobacteria) related catechol 2,3-dioxygenase genes, which belong to the I.2.C subfamily of extradiol dioxygenase genes. These catabolic genes encode

András Táncsics; István Szabó; Erzsébet Baka; Sándor Szoboszlay; József Kukolya; Balázs Kriszt; Károly Márialigeti

2010-01-01

335

Xanthine oxidase inhibitors from Garcinia esculenta twigs.  

PubMed

The EtOAc-soluble portion of the 80?% (v/v) EtOH extract from the twigs of Garcinia esculenta exhibited strong xanthine oxidase inhibition in vitro. Bioassay-guided purification led to the isolation of 1,3,6,7-tetrahydroxyxanthone (3) and griffipavixanthone (8) as the main xanthine oxidase inhibitors, along with six additional compounds (1, 2, 4-7), including two new compounds (1 and 2). This enzyme inhibition was dose dependent with an IC50 value of approximately 1.2?µM for 3 and 6.3?µM for 8. The inhibitory activity of 3 was stronger than the control allopurinol (IC50 value: 5.3?µM). To our knowledge, compound 8 is the first bixanthone that demonstrated potent XO inhibitory activity in vitro. The structures of the new compounds were established by spectroscopic analysis, and the optical properties and absolute stereochemistry of racemic (±) esculentin A (2) were further determined by the calculation of the DP4 probability and analysis of its MTPA ester derivatives. PMID:25340468

Zhu, Lun-Lun; Fu, Wen-Wei; Watanabe, Shimpei; Shao, Yi-Nuo; Tan, Hong-Sheng; Zhang, Hong; Tan, Chang-Heng; Xiu, Yan-Feng; Norimoto, Hisayoshi; Xu, Hong-Xi

2014-12-01

336

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

PubMed

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

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

2011-01-01

337

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

PubMed Central

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

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

2010-01-01

338

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

PubMed

The rpf genes and colS XOO1207/colR XOO1208 were known to require for virulence of Xanthomonas oryzae pv. oryzae (Xoo). In Xoo KACC10331 genome, two more colS/colR genes, colS XOO3534 (raxH)/colR XOO3535 (raxR) and colS XOO3762/colR XOO3763 were annotated. The colS XOO3534/colR XOO3535 were known to control AvrXa21 activity and functions of colS XOO3762/colR XOO3763 were unknown in Xoo. To characterize the relationship between rpf and colS/colR genes, expression of colS/colR genes in Rpf mutants of Xoo were analyzed with quantitative reverse transcription PCR (qRT-PCR). Expressions of all three colS/colR genes increased in the rpfF mutant in which DSF synthesis is defective. Expression of colS XOO1207/colR XOO1208, colS XOO3534/colR XOO3535 and colS XOO3762/colR XOO3763 increased 2, 2-7, 3-13 folds respectively. Expression of colS XOO3534 and colS XOO3762 also increased 2-4 folds in the rpfG mutant in which the signal from DSF is no longer transferred to down-stream. Expression of the other colS/colR genes was not significantly changed in the rpfG mutant compared to the wild type. Since RpfF and RpfG are responsible for DSF synthesis and signal transfer from DSF to down-stream to regulate virulence gene expression, these results suggest that the DSF and DSF-mediated signal regulate negatively three colS/colR genes in Xoo. PMID:25289017

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

2014-09-01

339

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

PubMed

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

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

2004-09-20

340

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

341

Chlorocatechelins A and B from Streptomyces sp.: new siderophores containing chlorinated catecholate groups and an acylguanidine structure.  

PubMed

Two novel siderophores, chlorocatechelins A and B, were isolated from a culture broth of Streptomyces sp. Their structures were determined by spectroscopic analysis and degradation study. They contain chloro-substituted catecholate that has not been reported in natural products, whereas this group was conjugated to guanidine to form acylguanidine in chlorocatechelin A. This acylguanidine decomposed in weakly acidic solutions to furnish a less potent siderophore chlorocatechelin B. Chemical and biological insights into acylguanidine are also discussed. PMID:25408968

Kishimoto, Shinji; Nishimura, Shinichi; Hattori, Akira; Tsujimoto, Masafumi; Hatano, Masaki; Igarashi, Masayuki; Kakeya, Hideaki

2014-12-01

342

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

Microsoft Academic Search

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

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

1997-01-01

343

Catechol-O-Methyltransferase Gene Polymorphism Modifies the Effect of Coffee Intake on Incidence of Acute Coronary Events  

Microsoft Academic Search

BackgroundThe role of coffee intake as a risk factor for coronary heart disease (CHD) has been debated for decades. We examined whether the relationship between coffee intake and incidence of CHD events is dependent on the metabolism of circulating catecholamines, as determined by functional polymorphism of the catechol-O-methyltransferase (COMT) gene.Methodology\\/Principal FindingsIn a cohort of 773 men who were 42 to

Pertti Happonen; Sari Voutilainen; Tomi-Pekka Tuomainen; Jukka T. Salonen; Thomas Zwaka

2006-01-01

344

Catechol-O-Methyltransferase Gene Polymorphism Modifies the Effect of Coffee Intake on Incidence of Acute Coronary Events  

Microsoft Academic Search

Background. The role of coffee intake as a risk factor for coronary heart disease (CHD) has been debated for decades. We examined whether the relationship between coffee intake and incidence of CHD events is dependent on the metabolism of circulating catecholamines, as determined by functional polymorphism of the catechol-O-methyltransferase (COMT) gene. Methodology\\/Principal Findings. In a cohort of 773 men who

Pertti Happonen; Sari Voutilainen; Tomi-Pekka Tuomainen; Jukka T. Salonen

2006-01-01

345

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

346

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

347

Alternative oxidase and plastoquinol terminal oxidase in marine prokaryotes of the Sargasso Sea.  

PubMed

Alternative oxidase (AOX) represents a non-energy conserving branch in mitochondrial electron transport while plastoquinol terminal oxidase (PTOX) represents a potential branch in photosynthetic electron transport. Using a metagenomics dataset, we have uncovered numerous and diverse AOX and PTOX genes from the Sargasso Sea. Sequence similarity, synteny and phylogenetic analyses indicate that the large majority of these genes are from prokaryotes. AOX appears to be widely distributed among marine Eubacteria while PTOX is widespread among strains of cyanobacteria closely related to the high-light adapted Prochlorococcus marinus MED4, as well as Synechococcus. The wide distribution of AOX and PTOX in marine prokaryotes may have important implications for productivity in the world's oceans. PMID:15777727

McDonald, Allison E; Vanlerberghe, Greg C

2005-04-11

348

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

349

Layer-by-layer assembly of bi-protein/layered double hydroxide ultrathin film and its electrocatalytic behavior for catechol.  

PubMed

This paper reports the fabrication of a bi-protein/layered double hydroxide (LDH) ultrathin film in which hemoglobin (HB) and horseradish peroxidase (HRP) molecules were assembled alternately with LDH nanosheets via the layer-by-layer (LBL) deposition technique, and its electrocatalytic performances for oxidation of catechol were demonstrated. The results of XRD indicate that the HB-HRP/LDH ultrathin film possesses a long range stacking order in the normal direction of the substrate, with the two proteins accommodated in the LDH gallery respectively as monolayer arrangement. SEM images show that the film surface exhibits a continuous and uniform morphology, and AFM reveals the Root-Mean-Square (RMS) roughness of ?10.2 nm for the film. A stable direct electrochemical redox behavior of the proteins was successfully obtained for the HB-HRP/LDH film modified electrode. In addition, it exhibits remarkable electrocatalytic activity towards oxidation of catechol, based on the synergistic effect of the two proteins. The catechol biosensor in this work displays a wide linear response range (6-170 ?M, r=0.999), low detection limit (5 ?M), high sensitivity and good reproducibility. PMID:20678920

Kong, Xianggui; Rao, Xiuying; Han, Jingbin; Wei, Min; Duan, Xue

2010-10-15

350

A structure-activity relationship study of catechol-O-methyltransferase inhibitors combining molecular docking and 3D QSAR methods.  

PubMed

A panel of 92 catechol-O-methyltransferase (COMT) inhibitors was used to examine the molecular interactions affecting their biological activity. COMT inhibitors are used as therapeutic agents in the treatment of Parkinson's disease, but there are limitations in the currently marketed compounds due to adverse side effects. This study combined molecular docking methods with three-dimensional structure-activity relationships (3D QSAR) to analyse possible interactions between COMT and its inhibitors, and to incite the design of new inhibitors. Comparative molecular field analysis (CoMFA) and GRID/GOLPE models were made by using bioactive conformations from docking experiments, which yielded q2 values of 0.594 and 0.636, respectively. The docking results, the COMT X-ray structure, and the 3D QSAR models are in agreement with each other. The models suggest that an interaction between the inhibitor's catechol oxygens and the Mg2+ ion in the COMT active site is important. Both hydrogen bonding with Lys144, Asn170 and Glu199, and hydrophobic contacts with Trp38, Pro174 and Leu198 influence inhibitor binding. Docking suggests that a large R1 substituent of the catechol ring can form hydrophobic contacts with side chains of Val173, Leu198, Met201 and Val203 on the COMT surface. Our models propose that increasing steric volume of e.g. the diethylamine tail of entacapone is favourable for COMT inhibitory activity. PMID:15124929

Tervo, Anu J; Nyrönen, Tommi H; Rönkkö, Toni; Poso, Antti

2003-12-01

351

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

PubMed Central

The anaerobic metabolism of catechol (1,2-dihydroxybenzene) was studied in the betaproteobacterium Thauera aromatica that was grown with CO2 as a cosubstrate and nitrate as an electron acceptor. Based on different lines of evidence and on our knowledge of enzymes and genes involved in the anaerobic metabolism of other aromatic substrates, the following pathway is proposed. Catechol is converted to catechylphosphate by phenylphosphate synthase, which is followed by carboxylation by phenylphosphate carboxylase at the para position to the phosphorylated phenolic hydroxyl group. The product, protocatechuate (3,4-dihydroxybenzoate), is converted to its coenzyme A (CoA) thioester by 3-hydroxybenzoate-CoA ligase. Protocatechuyl-CoA is reductively dehydroxylated to 3-hydroxybenzoyl-CoA, possibly by 4-hydroxybenzoyl-CoA reductase. 3-Hydroxybenzoyl-CoA is further metabolized by reduction of the aromatic ring catalyzed by an ATP-driven benzoyl-CoA reductase. Hence, the promiscuity of several enzymes and regulatory proteins may be sufficient to create the catechol pathway that is made up of elements of phenol, 3-hydroxybenzoate, 4-hydroxybenzoate, and benzoate metabolism. PMID:18156265

Ding, Bin; Schmeling, Sirko; Fuchs, Georg

2008-01-01

352

Electrocatalysis and simultaneous determination of catechol and quinol by poly(malachite green) coated multiwalled carbon nanotube film.  

PubMed

Electrochemically active composite film that contains multiwalled carbon nanotubes (MWCNTs), Nafion (NF), and poly(malachite green) (PMG) has been synthesized on glassy carbon electrode (GCE), gold, and indium tin oxide (ITO) electrodes by potentiodynamic method. The presence of MWCNTs in the composite film (MWCNT-NF-PMG) enhances the surface coverage concentration (?) of PMG by fivefold. Similarly, an electrochemical quartz crystal microbalance study revealed enhancement in the deposition of PMG at MWCNT-NF film when compared with bare and only NF modified electrodes. The surface morphology of the composite film was studied using atomic force microscopy, which revealed that the PMG incorporated on MWCNT-NF film. The composite film exhibited enhanced electrocatalytic activity toward the mixture of biochemical compounds catechol and quinol. The electrocatalytic responses of analytes at MWCNT-NF-PMG composite film were measured using both cyclic voltammetry (CV) and differential pulse voltammetry (DPV). From electrocatalysis studies, well-separated voltammetric peaks were obtained at the composite film for catechol and quinol with a peak separation of 147mV. The sensitivity values of the composite film toward catechol and quinol by the DPV technique were 0.4 and 3.2mAmM(-1)cm(-2), respectively, which are higher than the values obtained by the CV technique. Similarly, the above-mentioned values are better than the previously reported electroanalytical values for the same analytes. PMID:21138725

Umasankar, Yogeswaran; Periasamy, Arun Prakash; Chen, Shen-Ming

2011-04-01

353

Characterization of two amine oxidases from Aspergillus carbonarius AIU 205.  

PubMed

We have reported that Aspergillus carbonarius AIU 205, which was isolated by our group, produced three enzymes exhibiting oxidase activity for 4-aminobutanamide (4-ABAD) (J. Biosci. Bioeng., 117, 263-268 (2014)). Among three enzymes, characteristics of enzyme I have been revealed, but those of the other two enzymes have not. In this study, we purified enzymes II and III, and compared their characteristics with those of enzyme I. Enzymes II and III also oxidized aliphatic monoamines, aromatic amines, and aliphatic aminoalcohols. In addition, the oxidase activity of both enzymes was strongly inhibited by carbonyl reagents and specific inhibitors for copper-containing amine oxidases. Thus, enzymes II and III were also classified into the copper-containing amine oxidase group (EC 1.4.3.6) along with enzyme I. However, these three enzymes differed from each other in their enzymatic, kinetic, and physicochemical properties. The N-terminal amino acid sequences also differed from each other; that of enzyme I was modified, that of enzyme II was similar to those of peroxisomal copper-containing amine oxidases, and that of enzyme III was similar to those of copper-containing amine oxidases from the genus Aspergillus. Therefore, we concluded that A. carbonarius AIU 205 produced three different types of amine oxidase in the mycelia. PMID:25468423

Sugawara, Asami; Matsui, Daisuke; Yamada, Miwa; Asano, Yasuhisa; Isobe, Kimiyasu

2014-11-22

354

Natural variation of the rice blast resistance gene Pi-ta in Oryza species and its corresponding avirulence gene AVR-Pita in Magnaporthe oryzae  

Technology Transfer Automated Retrieval System (TEKTRAN)

The Pi-ta gene prevents the infections of M. oryzae races containing the corresponding avirulence gene AVR-Pita in a gene-for-gene manner. Pi-ta is a putative NBS type major resistance gene, and can directly recognize the AVR-Pita putative metalloprotease in triggering effective resistance. We hav...

355

XopR, a type III effector secreted by Xanthomonas oryzae pv. oryzae, suppresses microbe-associated molecular pattern-triggered immunity in Arabidopsis thaliana.  

PubMed

Xanthomonas oryzae pv. oryzae is the causal agent of bacterial blight of rice. The XopR protein, secreted into plant cells through the type III secretion apparatus, is widely conserved in xanthomonads and is predicted to play important roles in bacterial pathogenicity. Here, we examined the function of XopR by constructing transgenic Arabidopsis thaliana plants expressing it under control of the dexamethasone (DEX)-inducible promoter. In the transgenic plants treated with DEX, slightly delayed growth and variegation on leaves were observed. Induction of four microbe-associated molecular pattern (MAMP)-specific early-defense genes by a nonpathogenic X. campestris pv. campestris hrcC deletion mutant were strongly suppressed in the XopR-expressing plants. XopR expression also reduced the deposition of callose, an immune response induced by flg22. When transiently expressed in Nicotiana benthamiana, a XopR::Citrine fusion gene product localized to the plasma membrane. The deletion of XopR in X. oryzae pv. oryzae resulted in reduced pathogenicity on host rice plants. Collectively, these results suggest that XopR inhibits basal defense responses in plants rapidly after MAMP recognition. PMID:22204644

Akimoto-Tomiyama, Chiharu; Furutani, Ayako; Tsuge, Seiji; Washington, Erica J; Nishizawa, Yoko; Minami, Eiichi; Ochiai, Hirokazu

2012-04-01

356

The Oryza map alignment project: Construction, alignment and analysis of 12 BAC fingerprint/end sequence framework physical maps that represent the 10 genome types of genus Oryza  

Technology Transfer Automated Retrieval System (TEKTRAN)

The Oryza Map Alignment Project (OMAP) provides the first comprehensive experimental system for understanding the evolution, physiology and biochemistry of a full genus in plants or animals. We have constructed twelve deep-coverage BAC libraries that are representative of both diploid and tetraploid...

357

Direct Regulation of Cytochrome c Oxidase by Calcium Ions  

PubMed Central

Cytochrome c oxidase from bovine heart binds Ca2+ reversibly at a specific Cation Binding Site located near the outer face of the mitochondrial membrane. Ca2+ shifts the absorption spectrum of heme a, which allowed previously to determine the kinetics and equilibrium characteristics of the binding. However, no effect of Ca2+ on the functional characteristics of cytochrome oxidase was revealed earlier. Here we report that Ca2+ inhibits cytochrome oxidase activity of isolated bovine heart enzyme by 50–60% with Ki of ?1 µM, close to Kd of calcium binding with the oxidase determined spectrophotometrically. The inhibition is observed only at low, but physiologically relevant, turnover rates of the enzyme (?10 s?1 or less). No inhibitory effect of Ca2+ is observed under conventional conditions of cytochrome c oxidase activity assays (turnover number >100 s?1 at pH 8), which may explain why the effect was not noticed earlier. The inhibition is specific for Ca2+ and is reversed by EGTA. Na+ ions that compete with Ca2+ for binding with the Cation Binding Site, do not affect significantly activity of the enzyme but counteract the inhibitory effect of Ca2+. The Ca2+-induced inhibition of cytochrome c oxidase is observed also with the uncoupled mitochondria from several rat tissues. At the same time, calcium ions do not inhibit activity of the homologous bacterial cytochrome oxidases. Possible mechanisms of the inhibition are discussed as well as potential physiological role of Ca2+ binding with cytochrome oxidase. Ca2+- binding at the Cation Binding Site is proposed to inhibit proton-transfer through the exit part of the proton conducting pathway H in the mammalian oxidases. PMID:24058566

Vygodina, Tatiana; Kirichenko, Anna; Konstantinov, Alexander A.

2013-01-01

358

Visualization of monoamine oxidase in human brain  

SciTech Connect

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

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

1996-12-31

359

NADPH OXIDASE IN STROKE AND CEREBROVASCULAR DISEASE  

PubMed Central

NADPH oxidase (NOX) was originally identified in immune cells as playing an important microbicidal role. In stroke and cerebrovascular disease, inflammation is increasingly being recognized as contributing negatively to neurological outcome, with NOX as an important source of superoxide. Several labs have now shown that blocking or deleting NOX in the experimental stroke models protects from brain ischemic. Recent work has implicated glucose as an important NOX substrate leading to reperfusion injury, and that NOX inhibition can improve the detrimental effects of hyperglycemia on stroke. NOX inhibition also appears to ameliorate complications of thrombolytic therapy by reducing blood brain barrier disruption, edema formation and hemorrhage. Further, NOX from circulating inflammatory cells seems to contribute more to ischemic injury more than NOX generated from endogenous brain residential cells. Several pharmacological inhibitors of NOX are now available. Thus, blocking NOX activation may prove to be a promising treatment for stroke as well as an adjunctive agent to prevent its secondary complications. PMID:22643077

Tang, Xian Nan; Cairns, Belinda; Kim, Jong Youl; Yenari, Midori A.

2013-01-01

360

Degradation of pentachlorophenol by potato polyphenol oxidase.  

PubMed

In this study, polyphenol oxidase (PPO) was extracted from commercial potatoes. Degradation of pentachlorophenol by potato PPO was investigated. The experimental results show that potato PPO is more active in weak acid than in basic condition and that the optimum pH for the reaction is 5.0. The degradation of pentachlorophenol by potato PPO reaches a maximum at 298 K. After reaction for 1 h, the removal of both pentachlorophenol and total organic carbon is >70% with 6.0 units/mL potato PPO at pH 5.0 and 298 K. Pentachlorophenol can be degraded through dechlorination and ring-opening by potato PPO. The work demonstrates that pentachlorophenol can be effectively eliminated by crude potato PPO. PMID:21967325

Hou, Mei-Fang; Tang, Xiao-Yan; Zhang, Wei-De; Liao, Lin; Wan, Hong-Fu

2011-11-01

361

Gibberellin oxidase activities in Bradyrhizobium japonicum bacteroids.  

PubMed

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

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

2014-02-01

362

Phagocyte NADPH oxidase and specific immunity.  

PubMed

The phagocyte NADPH oxidase NOX2 produces reactive oxygen species (ROS) and is a well-known player in host defence. However, there is also increasing evidence for a regulatory role of NOX2 in adaptive immunity. Deficiency in phagocyte NADPH oxidase causes chronic granulomatous disease (CGD) in humans, a condition that can also be studied in CGD mice. Clinical observations in CGD patients suggest a higher susceptibility to autoimmune diseases, in particular lupus, idiopathic thrombocytopenic purpura and rheumatoid arthritis. In mice, a strong correlation exists between a polymorphism in a NOX2 subunit and the development of autoimmune arthritis. NOX2 deficiency in mice also favours lupus development. Both CGD patients and CGD mice exhibit increased levels of immunoglobulins, including autoantibodies. Despite these phenotypes suggesting a role for NOX2 in specific immunity, mechanistic explanations for the typical increase of CGD in autoimmune disease and antibody levels are still preliminary. NOX2-dependent ROS generation is well documented for dendritic cells and B-lymphocytes. It is unclear whether T-lymphocytes produce ROS themselves or whether they are exposed to ROS derived from dendritic cells during the process of antigen presentation. ROS are signalling molecules in virtually any cell type, including T- and B-lymphocytes. However, knowledge about the impact of ROS-dependent signalling on T- and B-lymphocyte phenotype and response is still limited. ROS might contribute to Th1/Th2/Th17 cell fate decisions during T-lymphocyte activation and might enhance immunoglobulin production by B-lymphocytes. In dendritic cells, NOX2-derived ROS might be important for antigen processing and cell activation. PMID:25760962

Cachat, Julien; Deffert, Christine; Hugues, Stephanie; Krause, Karl-Heinz

2015-05-01

363

The terminal oxidase in the marine bacterium Pseudomonas nautica 617.  

PubMed

The molecular properties of a novel membrane quinol oxidase from the marine bacterium Pseudomonas nautica 617 are presented. The protein contains 2b hemes/mole which may be distinguished by EPR spectroscopy but not by optical spectroscopy and electrochemistry. Respiration, though being cyanide insensitive, is not inhibited by carbon monoxide and oxygen reduction is carried out only half-way with production of hydrogen peroxide. The terminal oxidase represents, therefore, a unique example in the large family of terminal oxidases known up to date. PMID:9337488

Simpson, H; Denis, M; Malatesta, F

1997-06-01

364

Multilayered Polyelectrolyte Microcapsules: Interaction with the Enzyme Cytochrome C Oxidase  

PubMed Central

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

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

2014-01-01

365

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

366

Mitochondrial respiratory pathways inhibition in Rhizopus oryzae potentiates activity of posaconazole and itraconazole via apoptosis.  

PubMed

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

Shirazi, Fazal; Kontoyiannis, Dimitrios P

2013-01-01

367

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

PubMed

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

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

2014-12-10

368

Inhibition of catechol-o-methyltransferase (COMT) by myricetin, dihydromyricetin, and myricitrin.  

PubMed

Catechol O-methyltransferase (COMT) is an important enzyme involved in the metabolism of levodopa (L-dopa) which is clinically used to treat Parkinson's disease through boosting the concentration of dopamine in the brain. Development of COMT inhibitors can efficiently increase the bioavailability of L-dopa. The present study aims to evaluate the inhibition of COMT activity by three herbal components isolated from Myrica rubra Sieb. et Zucc.. The in vitro human liver cytosol-catalyzed L-dopa methylation reaction was utilized. The results showed that all these three compounds strongly inhibited COMT activity in a concentration-dependent manner. The inhibition was competitive for these three compounds, as demonstrated by Dixon and Lineweaver-Burk plots. The inhibition kinetic parameters (Ki) towards COMT activity were calculated to be 0.5, 0.2, and 0.9 microM for myricitrin, myricetin, and dihydromyricetin, respectively. From the view of structures, the deglycosylation biotransformation of myricitrin into myricetin can increase the inhibitory ability towards COMT. However, further structural alteration of myricetin towards dihydromyricetin weakens the inhibitory potential towards COMT. PMID:24716406

Zhu, Xu; Jia, Yun-Hong

2014-03-01

369

Bio-inspired catechol chemistry for electrophoretic nanotechnology of oxide films.  

PubMed

Bio-inspired chemical approach has been developed for the surface modification and electrophoretic deposition of manganese dioxide and zirconia nanoparticles, prepared by chemical precipitation methods. Caffeic acid, trans-cinnamic acid, p-coumaric acid, and 2,4-dihydroxycinnamic acid were investigated for the surface modification of the nanoparticles. The influence of the structure of the organic molecules on their adsorption on the oxide nanoparticles has been investigated. The mechanism of caffeic acid adsorption was similar to that of natural catecholic amino acid, L-3,4-dihydroxyphenylalanine. The use of caffeic acid allowed for agglomerate-free synthesis, efficient dispersion, charging, electrophoretic deposition and co-deposition of manganese dioxide and zirconia nanoparticles. The deposition yield data, coupled with the results of thermogravimetric analysis, X-ray diffraction analysis, and Fourier transform infrared spectroscopy, showed that surface chemistry, rather than the crystal structure, determined the adsorption behavior. Electron microscopy and energy dispersive spectroscopy investigations showed the formation of nanostructured oxide films and composites. The deposit composition can be varied. PMID:22652591

Wang, Y; Zhitomirsky, I

2012-08-15

370

Cytotoxicity of fumonisin B1, diethylnitrosamine, and catechol on the SNO esophageal cancer cell line.  

PubMed Central

Mycotoxins that commonly contaminate staple food grains pose a health hazard to animals and humans. Fumonisin B1 (FB1), a mycotoxin produced by Fusarium verticillioides, causes equine leukoencephalomalacia and porcine pulmonary edema and has been implicated in the etiology of esophageal cancer (EC) in the Transkei, South Africa. Various studies have indicated that nitrosamines induce EC, and F. verticillioides enhancement of nitrosamine-induced EC in rats has been reported. Dietary catechol (CAT), a constituent of cigarette smoke, was previously found to be a cocarcinogen with methyl-N-nitrosamine for inducing esophageal tumors in rats. In the present study we therefore investigated the cytotoxic effects of FB1, diethylnitrosamine (DEN), and CAT on a human esophageal epithelial cell line (SNO) using the methylthiazol tetrazolium assay. For each treatment, toxin concentrations ranged from 2.165 to 34.64 micro M. The results showed that the cytotoxic response of SNO cells was highest in cells treated with 34.64 micro M FB1. SNO cells treated with DEN + FB1 showed greater cytotoxicity than did cells treated with FB1 alone, whereas FB1 appeared to inhibit the cytotoxic effect exerted by CAT alone. The results of this study provide further evidence for the involvement of FB1 in the etiology of esophageal carcinoma. PMID:12153764

Myburg, Rene B; Dutton, Michael F; Chuturgoon, Anil A

2002-01-01

371

Methionine sulfoxide reductase regulates brain catechol-O-methyl transferase activity  

PubMed Central

Catechol-O-methyl transferase (COMT) plays a key role in the degradation of brain dopamine (DA). Specifically, low COMT activity results in higher DA levels in the prefrontal cortex (PFC), thereby reducing the vulnerability for attentional and cognitive deficits in both psychotic and healthy individuals. COMT activity is markedly reduced by a non-synonymous SNP that generates a valine-to-methionine substitution on the residue 108/158, by means of as-yet incompletely understood posttranslational mechanisms. One posttranslational modification is methionine sulfoxide, which can be reduced by the methionine sulfoxide reductase (Msr) A and B enzymes. We used recombinant COMT proteins (Val/Met108) and mice (wild-type (WT) and MsrA knockout) to determine the effect of methionine oxidation on COMT activity and COMT interaction with Msr, through a combination of enzymatic activity and Western blot assays. Recombinant COMT activity is positively regulated by MsrA, especially under oxidative conditions, while brains of MsrA knockout mice exhibited lower COMT activity (as compared with their WT counterparts). These results suggest that COMT activity may be reduced by methionine oxidation, and point to Msr as a key molecular determinant for the modulation of COMT activity in the brain. The role of Msr in modulating cognitive functions in healthy individuals and schizophrenia patients is yet to be determined. PMID:24735585

Moskovitz, Jackob; Walss-Bass, Consuelo; Cruz, Dianne A; Thompson, Peter M.; Bortolato, Marco

2015-01-01

372

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

SciTech Connect

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

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

2010-12-02

373

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

PubMed Central

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

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

2014-01-01

374

Association between catechol-O-methyltransferase Valą??Met polymorphism and configural mode of face processing.  

PubMed

Human visual system heavily relies on the spatial configuration among facial parts in discriminating faces. There are individual differences in the ability of configural face processing, which are supposed to be partly attributable to genetic predispositions. However, few studies have identified a specific gene linked to configural face processing ability. The present study investigated an association between configural mode of face processing and a single-nucleotide polymorphism in codon 158 of catechol-O-methyltransferase gene (COMT Val(158)Met polymorphism) using part-spacing paradigm. The results have revealed superior sensitivity to the changes in facial configuration in participants with Met/Met genotype of COMT Val(158)Met polymorphism compared to the other genotypes. This effect was virtually eliminated when the faces were presented upside-down. There was no group-difference in the ability to detect the change in morphological features of individual facial parts. These results indicate that COMT Val(158)Met polymorphism partly explains the individual differences in the ability of configural face processing. PMID:25481766

Doi, Hirokazu; Nishitani, Shota; Shinohara, Kazuyuki

2015-01-23

375

Schistosome and liver fluke derived catechol-estrogens and helminth associated cancers  

PubMed Central

Infection with helminth parasites remains a persistent public health problem in developing countries. Three of these pathogens, the liver flukes Clonorchis sinensis, Opisthorchis viverrini and the blood fluke Schistosoma haematobium, are of particular concern due to their classification as Group 1 carcinogens: infection with these worms is carcinogenic. Using liquid chromatography-mass spectrometry (LC-MS/MS) approaches, we identified steroid hormone like (e.g., oxysterol-like, catechol estrogen quinone-like, etc.) metabolites and related DNA-adducts, apparently of parasite origin, in developmental stages including eggs of S. haematobium, in urine of people with urogenital schistosomiasis, and in the adult stage of O. viverrini. Since these kinds of sterol derivatives are metabolized to active quinones that can modify DNA, which in other contexts can lead to breast and other cancers, helminth parasite associated sterols might induce tumor-like phenotypes in the target cells susceptible to helminth parasite associated cancers, i.e., urothelial cells of the bladder in the case of urogenital schistosomiasis and the bile duct epithelia or cholangiocytes, in the case of O. viverrini and C. sinensis. Indeed we postulate that helminth induced cancers originate from parasite estrogen-host epithelial/urothelial cell chromosomal DNA adducts, and here we review recent findings that support this conjecture. PMID:25566326

Correia da Costa, José M.; Vale, Nuno; Gouveia, Maria J.; Botelho, Mónica C.; Sripa, Banchob; Santos, Lúcio L.; Santos, Júlio H.; Rinaldi, Gabriel; Brindley, Paul J.

2014-01-01

376

Catechol-O-methyltransferase Val158Met polymorphism is associated with somatosensory amplification and nocebo responses.  

PubMed

A large number of unwanted adverse events and symptoms reported by patients in clinical trials are not caused by the drug provided, since most of adverse events also occur in corresponding placebo groups. These nocebo effects also play a major role in drug discontinuation in clinical practice, negatively affecting treatment efficacy as well as patient adherence and compliance. Experimental and clinical data document a large interindividual variability in nocebo responses, however, data on psychological, biological or genetic predictors of nocebo responses are lacking. Thus, with an established paradigm of behaviorally conditioned immunosuppressive effects we analyzed possible genetic predictors for nocebo responses. We focused on the genetic polymorphisms in the catechol-O-methyltransferase (COMT) gene (Val158Met) and analyzed drug specific and general side effects before and after immunosuppressive medication and subsequent placebo intake in 62 healthy male subjects. Significantly more drug-specific as well as general side effects were reported from homozygous carriers of the Val158 variant during medication as well as placebo treatment compared to the other genotype groups. Val158/Val158 carriers also had significantly higher scores in the somatosensory amplification scale (SSAS) and the BMQ (beliefs about medicine questionnaire). Together these data demonstrate potential genetic and psychological variables predicting nocebo responses after drug and placebo intake, which might be utilized to minimize nocebo effects in clinical trials and medical practice. PMID:25222607

Wendt, Laura; Albring, Antje; Benson, Sven; Engler, Harald; Engler, Andrea; Hinney, Anke; Rief, Winfried; Witzke, Oliver; Schedlowski, Manfred

2014-01-01

377

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

378

Catechol-O-Methyltransferase Val158Met Polymorphism Is Associated with Somatosensory Amplification and Nocebo Responses  

PubMed Central

A large number of unwanted adverse events and symptoms reported by patients in clinical trials are not caused by the drug provided, since most of adverse events also occur in corresponding placebo groups. These nocebo effects also play a major role in drug discontinuation in clinical practice, negatively affecting treatment efficacy as well as patient adherence and compliance. Experimental and clinical data document a large interindividual variability in nocebo responses, however, data on psychological, biological or genetic predictors of nocebo responses are lacking. Thus, with an established paradigm of behaviorally conditioned immunosuppressive effects we analyzed possible genetic predictors for nocebo responses. We focused on the genetic polymorphisms in the catechol-O-methyltransferase (COMT) gene (Val158Met) and analyzed drug specific and general side effects before and after immunosuppressive medication and subsequent placebo intake in 62 healthy male subjects. Significantly more drug-specific as well as general side effects were reported from homozygous carriers of the Val158 variant during medication as well as placebo treatment compared to the other genotype groups. Val158/Val158 carriers also had significantly higher scores in the somatosensory amplification scale (SSAS) and the BMQ (beliefs about medicine questionnaire). Together these data demonstrate potential genetic and psychological variables predicting nocebo responses after drug and placebo intake, which might be utilized to minimize nocebo effects in clinical trials and medical practice. PMID:25222607

Benson, Sven; Engler, Harald; Engler, Andrea; Hinney, Anke; Rief, Winfried; Witzke, Oliver; Schedlowski, Manfred

2014-01-01

379

Laccase Biosensor Based on Electrospun Copper/Carbon Composite Nanofibers for Catechol Detection  

PubMed Central

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

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

2014-01-01

380

Simultaneous saccharification and fermentation of potato starch wastewater to lactic acid by Rhizopus oryzae and Rhizopus arrhizus  

Microsoft Academic Search

The biochemical kinetic of simultaneous saccharification and fermentation (SSF) for lactic acid production by fungal species of Rhizopus arrhizus 36017 and Rhizopus oryzae 2062 was studied with respect to growth pH, temperature and substrate. Both R. arrhizus 36017 and R. oryzae 2062 had a capacity to carry out a single stage SSF process for lactic acid production from potato starch

Li Ping Huang; Bo Jin; Paul Lant; Jiti Zhou

2005-01-01

381

L-lactic acid production from starch by simultaneous saccharification and fermentation in a genetically engineered Aspergillus oryzae pure culture.  

PubMed

Lactic acid is a commodity chemical that can be produced biologically. Lactic acid-producing Aspergillus oryzae strains were constructed by genetic engineering. The A. oryzae LDH strain with the bovine L-lactate dehydrogenase gene produced 38 g/L of lactate from 100g/L of glucose. Disruption of the wild-type lactate dehydrogenase gene in A. oryzae LDH improved lactate production. The resulting strain A. oryzae LDH?871 produced 49 g/L of lactate from 100g/L of glucose. Because A. oryzae strains innately secrete amylases, A. oryzae LDH?871 produced approximately 30 g/L of lactate from various starches, dextrin, or maltose (all at 100 g/L). To our knowledge, this is the first report describing the simultaneous saccharification and fermentation of lactate from starch using a pure culture of transgenic A. oryzae. Our results indicate that A. oryzae could be a promising host for the bioproduction of useful compounds such as lactic acid. PMID:25314668

Wakai, Satoshi; Yoshie, Toshihide; Asai-Nakashima, Nanami; Yamada, Ryosuke; Ogino, Chiaki; Tsutsumi, Hiroko; Hata, Yoji; Kondo, Akihiko

2014-12-01

382

Preliminary assessment of resistance among U.S. wheat cultivars to the Triticum pathotype of Magnaporthe oryzae  

Technology Transfer Automated Retrieval System (TEKTRAN)

Magnaporthe oryzae is the causal agent of blast disease on several graminaceous plants. The M. oryzae population causing wheat blast has not been officially reported outside South America. U.S. wheat production is at risk to this pathogen if it is introduced and established. Proactive testing of U.S...

383

Action de l'herbicide molinate et de l'ure sur la sensibilit du riz Sclerotium oryzae Catt. et  

E-print Network

Action de l'herbicide molinate et de l'urée sur la sensibilité du riz ŕ Sclerotium oryzae Catt. et variétés de riz. L'action défavorable du molinate sur la maladie est plus importante que l'action Herbicide. Sclerotium oryzae, S. hydrophilum. SUMMARY Effect of the herbicide molinate and ofurea on the susceptibility

Paris-Sud XI, Université de

384

Native and Modified Lactate Dehydrogenase Expression in a Fumaric Acid Producing isolate Rhizopus oryzae 99-880  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizopus oryzae is a filamentous fungus that is of broad importance to the industrial, agricultural, and medical community. R. oryzae can be subdivided into two groups based on genetic and phenotypic differences. Type-I isolates accumulate primarily lactic acid when grown in the presence of a ferm...

385

MOLECULAR MECHANISMS OF THE INSTABILITY OF AVIRULENCE GENE AVR-PITA IN RICE BLAST FUNGUS MAGNAPORTHE ORYZAE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rice blast, caused by Magnaporthe Oryzae, is one of the most serious diseases of rice worldwide. The Pi-ta gene in rice confers resistance to M. Oryzae isolates containing the corresponding avirulence gene AVR-Pita. In the southern U.S., rice cultivars containing Pi-ta have been widely utilized sinc...

386

Diversification and evolution of the avirulence gene AVR-Pita1 in field isolates of Magnaporthe oryzae  

Technology Transfer Automated Retrieval System (TEKTRAN)

The study of the evolution of the AVR-Pita1 genes should benefit the deployment of the resistance gene Pi-ta for protecting rice production. The AVR-Pita1 avirulence gene in races of Magnaporthe oryzae triggers an effective resistance response when M. oryzae infects rice plants that contain the Pi-...

387

Expression profiling of common and specific defense responses of rice to Magnaporthe oryzae infection using deep sequencing technologies  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rice blast caused by Magnaporthe oryzae is a serious disease in rice production. Wild type Nipponbare and transgenic rice plants (carrying the Pi9 blast resistance gene) were challenged with the rice blast strain KJ201 to identify the early, mid and late host responses to M. oryzae infection at the ...

388

Mapping two major resistance genes in an indica cultivar Zhe733 to the race IE-1K of Magnaporthe oryzae  

Technology Transfer Automated Retrieval System (TEKTRAN)

Resistance (R) genes in rice confer resistance to races of Magnaporthe oryzae that contain the corresponding avirulence genes. The race IE-1K of M. oryzae recovered from the southern US overcomes R gene Pi-ta. The objectives of the present study were to identify new resistance sources to IE-1k an...

389

Characterization of a novel lipolytic enzyme from Aspergillus oryzae.  

PubMed

In this study, we report the characterization of a protein from Aspergillus oryzae, exhibiting sequence identity with paraben esterase from the genus Aspergillus. The coding region of 1,586 bp, including a 77-bp intron, encoded a protein of 502 amino acids. The gene without the signal peptide of 19 amino acids was cloned into a vector, pPICZ?C, and expressed successfully in Pichia pastoris as an active extracellular protein. The purified recombinant protein had pH and temperature optima of 7.0-8.0 and 30 °C, respectively, and was stable at the pH range of 7.0-10.0 and up to 40 °C. The optimal substrate for hydrolysis by the purified recombinant protein, among a panel of ?-naphthyl esters (C2-C16), was ?-naphthyl butyrate (C4), with activity of 0.16 units/mg protein. The considerable hydrolytic activity of the purified recombinant enzyme toward tributyrin was determined. However, no paraben esterase activity was detected toward the ethyl, propyl, and butyl esters of 4-hydroxybenzoic acid. In addition, no activity was detected toward the methyl esters of ferulic, p-coumaric, caffeic, and sinapic acids that would indicate feruloyl esterase activity. PMID:23001008

Koseki, Takuya; Asai, Shungo; Saito, Natsumi; Mori, Masayo; Sakaguchi, Yasuko; Ikeda, Kazutaka; Shiono, Yoshihito

2013-06-01

390

Proteomics study of silver nanoparticles toxicity on Oryza sativa L.  

PubMed

The increasing use of silver nanoparticles, (AgNPs), will inevitably result in their release into the environment and thereby cause the exposure to plants. It was claimed that using AgNPs is a safe and efficient method to preserve and treat agents of disease in agriculture. This study tries to understand the protein populations and sub-populations and follow up environmental AgNPs stresses. To accomplish these, the action of homemade spherical AgNPs colloidal suspension against Oryza sativa L. was investigated by a proteomic approach (2-DE and NanoLC/FT-ICR MS identification). Twenty-eight responsive (decrement/increment in abundance) proteins were identified. Proteomic results revealed that an exposure of O. sativa L., root with different concentrations of AgNPs resulted in an accumulation of protein precursors, indicative of the dissipation of a proton motive force. The identified proteins are involved in oxidative stress tolerance, Ca(2+) regulation and signaling, transcription and protein degradation, cell wall and DNA/RNA/protein direct damage, cell division and apoptosis. The expression pattern of these proteins and their possible involvement in the nontoxicity mechanisms were discussed. PMID:25124680

Mirzajani, Fateme; Askari, Hossein; Hamzelou, Sara; Schober, Yvonne; Römpp, Andreas; Ghassempour, Alireza; Spengler, Bernhard

2014-10-01

391

Investigation of tocotrienol biosynthesis in rice (Oryza sativa L.).  

PubMed

Rice tocotrienol (T3) has gained attention due to its physiological activities (e.g., antiangiogenesis). However, the biosynthetic pathway for T3 production in rice grain has not been well studied. We hypothesized that T3 biosynthesis enzymes and/or precursors play an important role in T3 production in whole grain. This proposal was evaluated in rice (Oryza sativa L.) by PCR and HPLC techniques. Grain tocopherol as well as flag leaf vitamin E levels were also investigated for comparison. For rice samples 14 days after flowering, grain was abundant in T3, but not in flag leaf. Expression of a gene encoding homogentisate geranylgeranyltransferase (HGGT, which has long been believed to be important for T3 production) differed significantly between grain and flag leaf. We then investigated rice samples during the grain maturation period, and found that grain T3 and HGGT levels increased in the early stage and then reached a plateau. T3 precursors such as homogentisate and geranylgeranyl pyrophosphate decreased during maturation. No increase in grain T3 from the middle to late stages of maturation and a decrease in T3 precursors during maturation suggest that HGGT would be an essential, but not limiting factor for T3 biosynthesis, and T3 precursors could regulate the T3 level in grain. The results of this study would be useful for nutraceutical purposes (e.g., development of T3-overproducing rice for the prevention of angiogenic disorders). PMID:23578619

Matsuzuka, Kentaro; Kimura, Eiichi; Nakagawa, Kiyotaka; Murata, Kazumasa; Kimura, Toshiyuki; Miyazawa, Teruo

2013-09-01

392

Aldehyde oxidase compartmentalization in Drosophila melanogaster wing imaginal disks.  

PubMed

Distribution of the enzyme aldehyde oxidase in mature Drosophilia melanogaster wing disks may allow visualization of known developmental compartments comprising (i) presumptive dorsal and ventral wing surfaces, and (ii) the presumptive anterior wing and the presumptive posterior wing. PMID:404707

Kuhn, D T; Cunningham, G N

1977-05-20

393

21 CFR 866.2420 - Oxidase screening test for gonorrhea.  

Code of Federal Regulations, 2011 CFR

...articles intended to identify by chemical reaction, cytochrome oxidase, an oxidizing enzyme that is associated with certain bacteria including Neisseria gonorrhoeae. A sample of a male's urethral discharge is obtained on a swab which is placed...

2011-04-01

394

Polyphenol Contents and Polyphenol Oxidase Activities of Some Nigerian Kolanuts  

Microsoft Academic Search

The levels of polyphenol and activities of polyphenol oxidases in some Nigerian kolanuts were investigated. Garcina cola had the least polyphenol content of 15.60±1.70 (mg\\/g), while Cola nitida (red) recorded the highest value of 33.50±2.51mg\\/g. Polyphenol oxidase from Garcina cola had its optimum pH of activity in t he acidic region (pH 3), but the white and red species of

T. P. Prohp; K. E. Ekpo; E. V. Osagie; A. Osagie; H. Obi

2009-01-01

395

Characterization of wheat germin (oxalate oxidase) expressed by Pichia pastoris  

Microsoft Academic Search

High-level secretory expression of wheat (Triticum aestivum) germin\\/oxalate oxidase was achieved in Pichia pastoris fermentation cultures as an ?-mating factor signal peptide fusion, based on the native wheat cDNA coding sequence. The oxalate oxidase activity of the recombinant enzyme is substantially increased (7-fold) by treatment with sodium periodate, followed by ascorbate reduction. Using these methods, approximately 1g (4×104U) of purified,

Heng-Yen Pan; Mei M. Whittaker; Romaric Bouveret; Anne Berna; François Bernier; James W.. Whittaker

2007-01-01

396

Protein-enriched pea flour extract protects stored milled rice against the rice weevil, Sitophilus oryzae.  

PubMed

Studies were conducted to evaluate the effect of a protein-enriched pea (Pisum sativum var. Bonneville) flour extract against the rice weevil, Sitophilus oryzae in its repellency, toxicity, effect on fecundity, stability and sensory properties. Milled rice admixed with pea flour extract at 1% concentration significantly repelled S. oryzae. Mortality of S. oryzae was found to increase and fecundity was markedly suppressed, in rice treated with 1% pea flour extract. The toxicity and reproductive effects of the pea protein-enriched rice were found to be stable for a period of 5 months. The sensory characteristics of stored rice when eaten were not affected by the treatment with pea flour extract. This study indicates that the protein-enriched flour extract obtained from the Bonneville pea may be feasible to protect stored milled rice from insect attack. PMID:15861241

Pretheep-Kumar, P; Mohan, S; Ramaraju, K

2004-01-01

397

Genome-wide identification of lineage-specific genes in Arabidopsis, Oryza and Populus  

SciTech Connect

Protein sequences were compared among Arabidopsis, Oryza and Populus to identify differential gene (DG) sets that are in one but not the other two genomes. The DG sets were screened against a plant transcript database, the NR protein database and six newly-sequenced genomes (Carica, Glycine, Medicago, Sorghum, Vitis and Zea) to identify a set of species-specific genes (SS). Gene expression, protein motif and intron number were examined. 192, 641 and 109 SS genes were identified in Arabidopsis, Oryza and Populus, respectively. Some SS genes were preferentially expressed in flowers, roots, xylem and cambium or up-regulated by stress. Six conserved motifs in Arabidopsis and Oryza SS proteins were found in other distant lineages. The SS gene sets were enriched with intronless genes. The results reflect functional and/or anatomical differences between monocots and eudicots or between herbaceous and woody plants. The Populus-specific genes are candidates for carbon sequestration and biofuel research.

Yang, Xiaohan [ORNL; Jawdy, Sara [ORNL; Tschaplinski, Timothy J [ORNL; Tuskan, Gerald A [ORNL

2009-01-01

398

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

PubMed

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

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

2014-09-01

399

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

NASA Astrophysics Data System (ADS)

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

Muni, Nurulhidayah Mat; Nadarajah, Kalaivani

2014-09-01

400

Triterpenoid glycosides from Medicago sativa as antifungal agents against Pyricularia oryzae.  

PubMed

The antifungal properties of saponin mixtures from alfalfa (Medicago sativa L.) tops and roots, the corresponding mixtures of prosapogenins from tops, and purified saponins and sapogenins against the causal agent of rice blast Pyricularia oryzae isolates are presented. In vitro experiments highlighted a range of activities, depending upon the assayed metabolite. The antifungal effects of the most promising prosapogenin mixture from alfalfa tops were confirmed by means of in planta tests using three different Italian cultivars of rice (Oryza sativa L. ssp. japonica), known to possess high, medium, and low blast resistance. The evidenced antifungal properties of the tested metabolites allowed some considerations on their structure-activity relationship. Results indicate that prosapogenins are active compounds to prevent the fungal attack of P. oryzae on different rice cultivars. Therefore, if properly formulated, these substances could represent a promising and environmentally friendly treatment to control rice blast. PMID:25361378

Abbruscato, Pamela; Tosi, Solveig; Crispino, Laura; Biazzi, Elisa; Menin, Barbara; Picco, Anna M; Pecetti, Luciano; Avato, Pinarosa; Tava, Aldo

2014-11-19

401

A new superoxide-generating oxidase in murine osteoclasts.  

PubMed

Superoxide production contributes to osteoclastic bone resorption. Evidence strongly indicates that NADPH oxidase is an enzyme system responsible for superoxide generation in osteoclasts. A membrane-bound subunit, p91, is the catalytic domain of NADPH oxidase. However, osteoclasts from p91 knockout mice still produce superoxide at a rate similar to that observed in wild type mice. This unexpected phenomenon prompted us to examine the osteoclasts for an alternative to the p91-containing oxidase. In this study, the cloning of a NADPH oxidase subunit (Nox 4) with 578 amino acids is reported. Nox 4 has 58% similarity in amino acids with the known p91 subunit of NADPH oxidase. Nox 4 is present and active in osteoclasts. Antisense oligonucleotides of Nox 4 reduced osteoclastic superoxide generation as well as resorption pit formation by osteoclasts. This new oxidase complex was present and functional in osteoclasts from p91 knockout mice, explaining the normal resorptive activity seen in the osteoclasts where no p91 is present. PMID:11098048

Yang, S; Madyastha, P; Bingel, S; Ries, W; Key, L

2001-02-23

402

Confirmation of a blocked amino terminus of sulfhydryl oxidase  

SciTech Connect

The isolation of sulfhydryl oxidase from bovine milk in a suitably pure form for sequencing was carried out by transient covalent affinity chromatography of diafiltered whey using cysteinylsuccinamidopropyl-glass as matrix. The glutathione-eluted proteins were separated by SDS-PAGE. By radiolabeling the affinity chromatography-purified enzyme with ({sup 14}C)iodoacetate before subjecting to SDS-PAGE, the sulfhydryl oxidase band was identified, because sulfhydryl oxidase is known to be inactivated by alkylation of one sulfhydryl group per mole. The results confirmed that sulfhydryl oxidase corresponds to the 85 ({plus minus} 5)-kDa band observed on SDS-PAGE. The protein band corresponding to radiolabeled sulfhydryl oxidase was recovered from SDS-PAGE gels by electrophoretic elution and by electroblotting on polyvinylidene difluoride membrane and subjected to gas phase sequencing. Precautions were taken during electrophoretic elution to prevent reactions that result in N-terminal blocking. Both methods of protein recovery yielded negative results when subjected to sequence analysis indicating that the N-terminus of sulfhydryl oxidase is blocked.

Janolino, V.G.; Morrison-Rowe, S.J.; Swaisgood, H.E. (North Carolina State Univ., Raleigh (USA))

1990-09-01

403

Lysyl oxidase activity regulates oncogenic stress response and tumorigenesis.  

PubMed

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

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

2013-01-01

404

Lysyl oxidase activity regulates oncogenic stress response and tumorigenesis  

PubMed Central

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

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

2013-01-01

405

Enhanced Production of Bovine Chymosin by Autophagy Deficiency in the Filamentous Fungus Aspergillus oryzae  

PubMed Central

Aspergillus oryzae has been utilized as a host for heterologous protein production because of its high protein secretory capacity and food-safety properties. However, A. oryzae often produces lower-than-expected yields of target heterologous proteins due to various underlying mechanisms, including degradation processes such as autophagy, which may be a significant bottleneck for protein production. In the present study, we examined the production of heterologous protein in several autophagy (Aoatg) gene disruptants of A. oryzae. We transformed A. oryzae gene disruptants of Aoatg1, Aoatg13, Aoatg4, Aoatg8, or Aoatg15, with a bovine chymosin (CHY) expression construct and found that the production levels of CHY increased up to three fold compared to the control strain. Notably, however, conidia formation by the Aoatg gene disruptants was significantly reduced. As large amounts of conidia are necessary for inoculating large-scale cultures, we also constructed Aoatg gene-conditional expression strains in which the promoter region of the Aoatg gene was replaced with the thiamine-controllable thiA promoter. Conidiation by the resultant transformants was clearly enhanced in the absence of thiamine, while autophagy remained repressed in the presence of thiamine. Moreover, these transformants displayed increased CHY productivity, which was comparable to that of the Aoatg gene disruptants. Consequently, we succeeded in the construction of A. oryzae strains capable of producing high levels of CHY due to defects in autophagy. Our finding suggests that the conditional regulation of autophagy is an effective method for increasing heterologous protein production in A. oryzae. PMID:23658635

Maruyama, Jun-ichi; Kitamoto, Katsuhiko

2013-01-01

406

Purification of enzymatically active human lysyl oxidase and lysyl oxidase-like protein from Escherichia coli inclusion bodies  

Microsoft Academic Search

Lysyl oxidase (LOX) is an extracellular copper dependent enzyme catalyzing lysine-derived cross-links in extracellular matrix proteins. Recent molecular cloning has revealed the existence of a LOX family consisting of LOX and four lysyl oxidase-like proteins (LOXLs; LOXL, LOXL2, LOXL3, and LOXL4). Each member of the LOX family contains a copper-binding domain, residues for lysyl-tyrosyl quinone, and a cytokine receptor-like domain.

Sang Taek Jung; Moon Suk Kim; Ji Yeon Seo; Hyung Chul Kim; Youngho Kim

2003-01-01

407

Polymer pendant ligand chemistry. 3. A biomimetic approach to selective metal ion removal and recovery from aqueous solution with polymer-supported sulfonated catechol and linear catechol amide ligands  

SciTech Connect

The design of organic ligands to selectively remove and recover metal ions from aqueous solution is a new and important area of environmental inorganic chemistry. One approach to designing organic ligands for these purposes is to use biological systems as examples for selective metal ion complexation. Thus, the authors report results on the synthesis of several biomimetically important polymer-supported, sulfonated catechol (PS-CATS), sulfonated bis(catechol) linear amide (PS-2-6-LICAMS), and sulfonated 3.3-linear tris(catechol) amide (PS-3,3-LICAMS) ligands that are chemically bonded to modified 6% cross-linked macroporous polystyrene-divinylbenzene beads (PS-DVB) for selective removal and recovery of environmentally and economically important metal ions from aqueous solution, as a function of pH. The Fe{sup 3+} ion selectivity was dramatically shown for PS-CATS, PS-2-6-LICAMS and PS-3,3-LICAMS polymer beads in competition with a similar concentration of Cu{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, Ni{sup 2+}, Mg{sup 2+}, Al{sup 3+}, and Cr{sup 3+} ions at pH 1-3, while metal ion selectivity could be changed at higher pH values in the absence of Fe{sup 3+} (for example, Hg{sup 2+} at pH 3). Rates of removal and recovery of the Fe{sup 3+} ion with the PS-CATS, PS-2-6LICAMS and PS-3,3-LICAMS polymer beads were also studied as well as relative equilibrium selectivity coefficient (K{sub m}) values for all metal competition studies.

Huang, Song-Ping; Li, Wei; Franz, K.J.; Albright, R.L.; Fish, R.H. [Univ. of California, Berkeley, CA (United States)

1995-05-24

408

Chronic monoamine oxidase-B inhibitor treatment blocks monoamine oxidase-A enzyme activity.  

PubMed

Patients with Parkinson's disease receive selective irreversible monoamine oxidase (MAO)-B inhibitors, but their effects on MAO-A activity are not known during long-term application. We determined MAO-A inhibition in plasma samples from patients with MAO-B inhibitor intake or without MAO-B inhibitor treatment and from healthy controls. We detected a 70 % reduction of MAO-A activity in patients with MAO-B inhibitor therapy in comparison to the other groups. Our results suggest that treatment with MAO-B inhibitor may also influence MAO-A activity in vivo, when administered daily. PMID:24272680

Bartl, Jasmin; Müller, Thomas; Grünblatt, Edna; Gerlach, Manfred; Riederer, Peter

2014-04-01

409

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

PubMed

Laccase (EC 1.10.3.2) is an enzyme with p-diphenol oxidase activity that is a member of a group of proteins collectively known as multicopper, or blue copper, oxidases. Laccase is hypothesized to play an important role in insect cuticle sclerotization by oxidizing catechols in the cuticle to their corresponding quinones, which then catalyze protein cross-linking reactions. To facilitate studies of the structure, function and regulation of insect laccases, we have cloned two cDNAs for laccases from the tobacco hornworm, Manduca sexta (MsLac1 and 2), and one from the malaria mosquito, Anopheles gambiae (AgLac1). The MsLac1 and 2 cDNAs encode proteins of 801 amino acids (aa) and 760 aa, respectively, while the AgLac1 cDNA encodes a protein of 1009 aa. All three cDNAs contain putative secretion signal sequences, and the 10 histidines and one cysteine that form the copper-binding centers, as well as a methionine in the T1 copper center. Novel to the insect laccases, relative to both fungal and plant laccases, is a longer amino-terminal sequence characterized by a unique domain consisting of several conserved cysteine, aromatic, and charged residues. Northern blot analyses identified single transcripts of approximately 3.6, 3.5, and 4.4 kb for MsLac1, MsLac2, and AgLac1, respectively, and also showed that AgLac1 was expressed in all life stages of the mosquito. RT-PCR revealed that the MsLac1 transcript was most abundant in the midgut, Malpighian tubules, and epidermis, whereas the MsLac2 transcript was most abundant in the epidermis. MsLac2 showed strong expression in the pharate pupal and reduced expression in the early pupal epidermis, consistent with the laccases' presumed role in cuticle sclerotization. PMID:14723895

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

2004-01-01

410

Monoamine oxidase inactivation: from pathophysiology to therapeutics  

PubMed Central

Monoamine oxidases (MAOs) A and B are mitochondrial bound isoenzymes which catalyze the oxidative deamination of dietary amines and monoamine neurotransmitters, such as serotonin, norepinephrine, dopamine, ?-phenylethylamine and other trace amines. The rapid degradation of these molecules ensures the proper functioning of synaptic neurotransmission and is critically important for the regulation of emotional behaviors and other brain functions. The byproducts of MAO-mediated reactions include several chemical species with neurotoxic potential, such as hydrogen peroxide, ammonia and aldehydes. As a consequence, it is widely speculated that prolonged excessive activity of these enzymes may be conducive to mitochondrial damages and neurodegenerative disturbances. In keeping with these premises, the development of MAO inhibitors has led to important breakthroughs in the therapy of several neuropsychiatric disorders, ranging from mood disorders to Parkinson’s disease. Furthermore, the characterization of MAO knockout (KO) mice has revealed that the inactivation of this enzyme produces a number of functional and behavioral alterations, some of which may be harnessed for therapeutic aims. In this article, we discuss the intriguing hypothesis that the attenuation of the oxidative stress induced by the inactivation of either MAO isoform may contribute to both antidepressant and antiparkinsonian actions of MAO inhibitors. This possibility further highlights MAO inactivation as a rich source of novel avenues in the treatment of mental disorders. PMID:18652859

Bortolato, Marco; Chen, Kevin; Shih, Jean C

2008-01-01

411

Crystallization of beef heart cytochrome c oxidase  

NASA Astrophysics Data System (ADS)

The three-dimensional structure of cytochrome c oxidase, a complex (multimetal, multisubunit) membrane protein is critical to elucidation of the mechanism of the enzymic reactions and their control. Our recent developments in the crystallization of the enzyme isolated from beef hearts are presented. The crystals appeared more readily at higher protein concentration, lower ionic strength, higher detergent concentration (Brij-35) and lower temperature. Large crystals were obtained by changing one of these parameters to the crystallization point as slowly as possible, keeping the other parameters constant. Increasing the detergent concentration was the most successful method, producing green crystals of the resting oxidized form as hexagonal bipyramids with typical dimensions of 0.6 mm. The usual procedures for crystallization of water soluble proteins, such as increasing ionic strength by vapor diffusion, were not applicable for this enzyme. Crystals of the resting oxidized enzyme belong to a space group of P6 2 or P6 4 with cell dimensions, a = b = 208.7 Ĺ and c = 282.3 Ĺ. The Patterson function shows that the crystal exhibited a non-crystallographic two-fold axis parallel to the c-axis in the asymmetric unit.

Yoshikawa, Shinya; Shinzawa, Kyoko; Tsukihara, Tomitake; Abe, Toshio; Caughey, Winslow S.

1991-03-01

412

Modular assembly of yeast cytochrome oxidase  

PubMed Central

Previous studies of yeast cytochrome oxidase (COX) biogenesis identified Cox1p, one of the three mitochondrially encoded core subunits, in two high–molecular weight complexes combined with regulatory/assembly factors essential for expression of this subunit. In the present study we use pulse-chase labeling experiments in conjunction with isolated mitochondria to identify new Cox1p intermediates and place them in an ordered pathway. Our results indicate that before its assimilation into COX, Cox1p transitions through five intermediates that are differentiated by their compositions of accessory factors and of two of the eight imported subunits. We propose a model of COX biogenesis in which Cox1p and the two other mitochondrial gene products, Cox2p and Cox3p, constitute independent assembly modules, each with its own complement of subunits. Unlike their bacterial counterparts, which are composed only of the individual core subunits, the final sequence in which the mitochondrial modules associate to form the holoenzyme may have been conserved during evolution. PMID:23266989

McStay, Gavin P.; Su, Chen Hsien; Tzagoloff, Alexander

2013-01-01

413

MONOAMINE OXIDASE: RADIOTRACER DEVELOPMENT AND HUMAN STUDIES.  

SciTech Connect

PET is uniquely capable of providing information on biochemical transformations in the living human body. Although most of the studies of monoamine oxidase (MAO) have focused on measurements in the brain, the role of peripheral MAO as a phase 1 enzyme for the metabolism of drugs and xenobiotics is gaining attention (Strolin Benedetti and Tipton, 1998; Castagnoli et al., 1997.). MAO is well suited for this role because its concentration in organs such as kidneys, liver and digestive organs is high sometimes exceeding that in the brain. Knowledge of the distribution of the MAO subtypes within different organs and different cells is important in determining which substrates (and which drugs and xenobiotics) have access to which MAO subtypes. The highly variable subtype distribution with different species makes human studies even more important. In addition, the deleterious side effects of combining MAO inhibitors with other drugs and with foodstuffs makes it important to know the MAO inhibitory potency of different drugs both in the brain and in peripheral organs (Ulus et al., 2000). Clearly PET can play a role in answering these questions, in drug research and development and in discovering some of the factors which contribute to the highly variable MAO levels in different individuals.

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

2000-09-28

414

Alzheimer disease ?-amyloid activity mimics cholesterol oxidase  

PubMed Central

The abnormal accumulation of amyloid ?-peptide (A?) in the form of senile (or amyloid) plaques is one of the main characteristics of Alzheimer disease (AD). Both cholesterol and Cu2+ have been implicated in AD pathogenesis and plaque formation. A? binds Cu2+ with very high affinity, forming a redox-active complex that catalyzes H2O2 production from O2 and cholesterol. Here we show that A?:Cu2+ complexes oxidize cholesterol selectively at the C-3 hydroxyl group, catalytically producing 4-cholesten-3-one and therefore mimicking the activity of cholesterol oxidase, which is implicated in cardiovascular disease. A? toxicity in neuronal cultures correlated with this activity, which was inhibited by Cu2+ chelators including clioquinol. Cell death induced by staurosporine or H2O2 did not elevate 4-cholesten-3-one levels. Brain tissue from AD subjects had 98% more 4-cholesten-3-one than tissue from age-matched control subjects. We observed a similar increase in the brains of Tg2576 transgenic mice compared with nontransgenic littermates; the increase was inhibited by in vivo treatment with clioquinol, which suggests that brain A? accumulation elevates 4-cholesten-3-one levels in AD. Cu2+-mediated oxidation of cholesterol may be a pathogenic mechanism common to atherosclerosis and AD. PMID:16127459

Puglielli, Luigi; Friedlich, Avi L.; Setchell, Kenneth D.R.; Nagano, Seiichi; Opazo, Carlos; Cherny, Robert A.; Barnham, Kevin J.; Wade, John D.; Melov, Simon; Kovacs, Dora M.; Bush, Ashley I.

2005-01-01

415

Comparison of the genomes and transcriptomes associated with the different protease secretions of Aspergillus oryzae 100-8 and 3.042.  

PubMed

Aspergillus oryzae is used to produce traditional fermented foods and beverages. A. oryzae 3.042 produces a neutral protease and an alkaline protease but rarely an acid protease, which is unfavourable to soy-sauce fermentation. A. oryzae 100-8 was obtained by N(+) ion implantation mutagenesis of A. oryzae 3.042, and the protease secretions of these two strains are different. Sequencing the genome of A. oryzae 100-8 and comparing it to the genomes of A. oryzae 100-8 and 3.042 revealed some differences, such as single nucleotide polymorphisms, nucleotide deletion or insertion. Some of these differences may reflect the ability of A. oryzae to secrete proteases. Transcriptional sequencing and analysis of the two strains during the same growth processes provided further insights into the genes and pathways involved in protease secretion. PMID:25048221

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

2014-10-01

416

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

PubMed

Fibromyalgia syndrome (FS) is a rheumatic syndrome affecting to 2-3% of individuals of productive age, mainly women. Neuroendocrine and genetic factors may play a significant role in development of the disease which is characterized by diffuse chronic pain and presence of tender points. Several studies have suggested an association between FS, especially pain sensitivity, and polymorphism of the catechol-O-methyltransferase (COMT) gene. The aim of the present study was to characterize the SNPs rs4680 and rs4818 of the COMT gene and assess its influence in pain sensitivity of patients with fibromyalgia screened by the Fibromyalgia Impact Questionnaire (FIQ). DNA was extracted from peripheral blood of 112 patients with fibromyalgia and 110 healthy individuals and was used as template in PCR for amplification of a 185-bp fragment of the COMT gene. The amplified fragment was sequenced for analyses of the SNPs rs4680 and rs4818. The frequency of mutant genotype AA of SNP rs6860 was 77.67% in patients with FS and 28.18% for the control group. For the SNP rs4818, the frequency of mutant genotype CC was 73.21 and 39.09% for patients with FS and controls, respectively. Moreover, the FIQ score was higher in patients with the homozygous mutant genotype for SNPs rs4680 (87.92 points) and rs4818 (86.14 points). These results suggest that SNPs rs4680 and rs4818 of the COMT gene may be associated with fibromyalgia and pain sensitivity in FS Brazilian patients. PMID:21120493

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

2012-02-01

417

Kinetic and inhibition studies on catechol-O-methyltransferase affinity labelling by N-(3,4-dihydroxyphenyl)maleimide.  

PubMed Central

Initial velocity and product inhibition studies have been performed on soluble catechol-O-methyltransferase which has been partially purified from pig liver. The results are consistent with an ordered reaction mechanism, in which S-adenosyl-L-methionine (AdoMet) is the leading substrate. The enzyme is irreversibly inhibited by maleimide derivatives in a biphasic manner, which suggests a differential reaction with two thiol groups. N-(3,4-Dihydroxyphenyl)maleimide, which has a reactive moiety (maleimide ring) and an affinity moiety (catechol ring), acts as an affinity labelling compound on the more reactive SH group; AdoMet and Mg2+ protect against this modification. Total protection of this SH group results in a pseudo-first-order inhibition of the enzyme, with the apparent rate constant being proportional to the inhibitor concentration. All the other maleimide derivatives studied inhibited the enzyme by reacting with one of the two SH groups in a non-specific manner. The reaction of the other, more reactive, SH group was either specific (active-site-directed) or non-specific, depending on the substituent present in the affinity moiety and also on the length of an intermediate chain of methylene groups present between this moiety and the reactive maleimide ring. In the presence of both AdoMet and Mg2+, 3,5-dinitrocatechol, a reversible inhibitor of the enzyme which is competitive with respect to the catechol substrate, protects the enzyme from inactivation by any of the maleimide derivatives. The adducts of these maleimide derivatives formed with dithiothreitol inhibit the enzyme reversibly, showing inhibition patterns that are consistent with the mechanism deduced from the initial velocity and product inhibition studies. PMID:1417755

Piedrafita, F J; Fernandez-Alvarez, E; Nieto, O; Tipton, K F

1992-01-01

418

Robustness and Strategies of Adaptation among Farmer Varieties of African Rice (Oryza glaberrima) and Asian Rice (Oryza sativa) across West Africa  

PubMed Central

This study offers evidence of the robustness of farmer rice varieties (Oryza glaberrima and O. sativa) in West Africa. Our experiments in five West African countries showed that farmer varieties were tolerant of sub-optimal conditions, but employed a range of strategies to cope with stress. Varieties belonging to the species Oryza glaberrima – solely the product of farmer agency – were the most successful in adapting to a range of adverse conditions. Some of the farmer selections from within the indica and japonica subspecies of O. sativa also performed well in a range of conditions, but other farmer selections from within these two subspecies were mainly limited to more specific niches. The results contradict the rather common belief that farmer varieties are only of local value. Farmer varieties should be considered by breeding programmes and used (alongside improved varieties) in dissemination projects for rural food security. PMID:23536754

Maat, Harro; Richards, Paul; Struik, Paul C.

2013-01-01

419

Cytokinin Oxidase from Phaseolus vulgaris Callus Tissues 1  

PubMed Central

The effects of metal ions on cytokinin oxidase activity extracted from callus tissues of Phaseolus vulgaris L. cv Great Northern have been examined using an assay based on the oxidation of N6-(?2-isopentenyl)-adenine-2,8-3H (i6 Ade) to adenine (Ade). The addition of cupric ions to reaction mixtures containing imidazole buffer markedly enhanced cytokinin oxidase activity. In the presence of optimal concentrations of copper and imidazole, cytokinin oxidase activity was stimulated more than 20-fold. The effect was enzyme dependent, specific for copper, and observed only in the presence of imidazole. The substrate specificity of the copper-imidazole enhanced reaction, as judged by substrate competition tests, was the same as that observed in the absence of copper and imidazole. Similarly, in tests involving DEAE-cellulose chromatography, elution profiles of cytokinin oxidase activity determined using a copper-imidazole enhanced assay were identical to those obtained using an assay without copper and imidazole. On the basis of these results, the addition of copper and imidazole to reaction mixtures used to assay for cytokinin oxidase activity is judged to provide a reliable and specific assay of greatly enhanced sensitivity for the enzyme. The mechanism by which copper and imidazole enhance cytokinin oxidase activity is not certain, but the reaction catalyzed by the enzyme was not inhibited by anaerobic conditions when these reagents were present. This observation suggests that copper-imidazole complexes are substituting for oxygen in the reaction mechanism by which cytokinin oxidase effects cleavage of the N6-side chain of i6Ade. PMID:16665511

Chatfield, J. Mark; Armstrong, Donald J.

1987-01-01

420

HIF-1? Activation by Intermittent Hypoxia Requires NADPH Oxidase Stimulation by Xanthine Oxidase  

PubMed Central

Hypoxia-inducible factor 1 (HIF-1) mediates many of the systemic and cellular responses to intermittent hypoxia (IH), which is an experimental model that simulates O2 saturation profiles occurring with recurrent apnea. IH-evoked HIF-1? synthesis and stability are due to increased reactive oxygen species (ROS) generated by NADPH oxidases, especially Nox2. However, the mechanisms by which IH activates Nox2 are not known. We recently reported that IH activates xanthine oxidase (XO) and the resulting increase in ROS elevates intracellular calcium levels. Since Nox2 activation requires increased intracellular calcium levels, we hypothesized XO-mediated calcium signaling contributes to Nox activation by IH. We tested this possibility in rat pheochromocytoma PC12 cells subjected to IH consisting alternating cycles of hypoxia (1.5% O2 for 30 sec) and normoxia (21% O2 for 5 min). Kinetic analysis revealed that IH-induced XO preceded Nox activation. Inhibition of XO activity either by allopurinol or by siRNA prevented IH-induced Nox activation, translocation of the cytosolic subunits p47phox and p67phox to the plasma membrane and their interaction with gp91phox. ROS generated by XO also contribute to IH-evoked Nox activation via calcium-dependent protein kinase C stimulation. More importantly, silencing XO blocked IH-induced upregulation of HIF-1? demonstrating that HIF-1? activation by IH requires Nox2 activation by XO. PMID:25751622

Nanduri, Jayasri; Vaddi, Damodara Reddy; Khan, Shakil A.; Wang, Ning; Makarenko, Vladislav; Semenza, Gregg L.; Prabhakar, Nanduri R.

2015-01-01

421

The blood-brain barrier-permeable catechol-O-methyltransferase inhibitor dinitrocatechol suppresses experimental autoimmune encephalomyelitis.  

PubMed

Reduced levels of noradrenaline (NA) in CNS of multiple sclerosis patients could be due to metabolism by catechol-O-methyltransferase (COMT). In mice immunized with myelin oligodendrocyte glycoprotein peptide, the BBB-permeable COMT inhibitor dinitrocatechol (DNC) reduced clinical signs, while entacapone, a non-BBB-permeable inhibitor, had no effect. Spinal cord NA levels were slightly increased by DNC, and there was an inverse correlation between NA levels and average clinical signs. Spinal cord COMT mRNA levels were not increased during EAE, but were found increased in the frontal cortex of MS patients. These results suggest that COMT inhibitors could provide benefit to MS patients. PMID:25242632

Polak, Paul E; Lin, Shao Xia; Pelligrino, Dale; Feinstein, Douglas L

2014-11-15

422

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

PubMed Central

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

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

2011-01-01

423

Homology modeling, simulation and molecular docking studies of catechol-2, 3-Dioxygenase from Burkholderia cepacia: Involved in degradation of Petroleum hydrocarbons  

PubMed Central

Catechol 2, 3-dioxygenase is present in several types of bacteria and undergoes degradation of environmental pollutants through an important key biochemical pathways. Specifically, this enzyme cleaves aromatic rings of several environmental pollutants such as toluene, xylene, naphthalene and biphenyl derivatives. Hence, the importance of Catechol 2, 3-dioxygenase and its role in the degradation of environmental pollutants made us to predict the three-dimensional structure of Catechol 2, 3-dioxygenase from Burkholderia cepacia. The 10ns molecular dynamics simulation was carried out to check the stability of the modeled Catechol 2, 3- dioxygenase. The results show that the model was energetically stable, and it attains their equilibrium within 2000 ps of production MD run. The docking of various petroleum hydrocarbons into the Catechol 2,3-dioxygenase reveals that the benzene, O-xylene, Toluene, Fluorene, Naphthalene, Carbazol, Pyrene, Dibenzothiophene, Anthracene, Phenanthrene, Biphenyl makes strong hydrogen bond and Van der waals interaction with the active site residues of H150, L152, W198, H206, H220, H252, I254, T255, Y261, E271, L276 and F309. Free energy of binding and estimated inhibition constant of these compounds demonstrates that they are energetically stable in their binding cavity. Chrysene shows positive energy of binding in the active site atom of Fe. Except Pyrene all the substrates made close contact with Fe atom by the distance ranges from 1.67 to 2.43 Ĺ. In addition to that, the above mentioned substrate except pyrene all other made ?-? stacking interaction with H252 by the distance ranges from 3.40 to 3.90 Ĺ. All these docking results reveal that, except Chrysene all other substrate has good free energy of binding to hold enough in the active site and makes strong VdW interaction with Catechol-2,3-dioxygenase. These results suggest that, the enzyme is capable of catalyzing the above-mentioned substrate. PMID:23144539

Ajao, AT; Kannan, M; Yakubu, SE; VJ, Umoh; JB, Ameh

2012-01-01

424

Rice bacterial blight pathogen Xanthomonas oryzae pv. oryzae produces multiple DSF-family signals in regulation of virulence factor production  

PubMed Central

Background Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of rice bacterial blight disease. Xoo produces a range of virulence factors, including EPS, extracellular enzyme, iron-chelating siderophores, and type III-secretion dependent effectors, which are collectively essential for virulence. Genetic and genomics evidence suggest that Xoo might use the diffusible signal factor (DSF) type quorum sensing (QS) system to regulate the virulence factor production. However, little is known about the chemical structure of the DSF-like signal(s) produced by Xoo and the factors influencing the signal production. Results Xoo genome harbours an rpf cluster comprising rpfB, rpfF, rpfC and rpfG. The proteins encoded by these genes are highly homologous to their counterparts in X. campestris pv. campestris (Xcc), suggesting that Xcc and Xoo might use similar mechanisms for DSF biosynthesis and autoregulation. Consistent with in silico analysis, the rpfF mutant was DSF-deficient and the rpfC mutant produced about 25 times higher DSF-like activity than the wild type Xoo strain KACC10331. From the supernatants of rpfC mutant, we purified three compounds showing strong DSF-like activity. Mass spectrometry and NMR analysis revealed that two of them were the previously characterized DSF and BDSF; the third one was a novel unsaturated fatty acid with 2 double bonds and was designated as CDSF in this study. Further analysis showed that all the three DSF-family signals were synthesized via the enzyme RpfF encoded by Xoo2868. DSF and BDSF at a final concentration of 3 ?M to the rpfF mutant could fully restore its extracellular xylanase activity and EPS production to the wild type level, but CDSF was less active than DSF and BDSF in induction of EPS and xylanase. DSF and CDSF shared a similar cell density-dependent production time course with the maximum production being detected at 42 h after inoculation, whereas the maximum production of BDSF was observed at 36 h after inoculation. When grown in a rich medium such as YEB, LB, PSA, and NYG, Xoo produced all the three signals with the majority being DSF. Whereas in nutritionally poor XOLN medium Xoo only produced BDSF and DSF but the majority was BDSF. Conclusions This study demonstrates that Xoo and Xcc share the conserved mechanisms for DSF biosynthesis and autoregulation. Xoo produces DSF, BDSF and CDSF signals in rich media and CDSF is a novel signal in DSF-family with two double bonds. All the three DSF-family signals promote EPS production and xylanase activity in Xoo, but CDSF is less active than its analogues DSF and BDSF. The composition and ratio of the three DSF-family signals produced by Xoo are influenced by the composition of culture media. PMID:20615263

2010-01-01

425

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

PubMed

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

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

2014-05-01

426

Fabrication of mussel-inspired highly adhesive honeycomb films containing catechol groups and their applications for substrate-independent porous templates.  

PubMed

Porous surface patterns are used in a wide variety of practical applications. Honeycomb-patterned porous polymer films are good templates for preparing porous surfaces due to their simple fabrication and the arrangement of pores on the surface. Catechol groups include in adhesive protein of mussels have attracted much attention due to their highly and substrate-independent adhesive properties. In this paper, highly and substrate-independent adhesive honeycomb-patterned porous polymer films are prepared by using amphiphilic copolymer having catechol moieties. Furthermore, porous surface patterns are transferred on various organic or inorganic substrates by wet etching with using adhesive honeycomb films as templates. PMID:23508892

Saito, Yuta; Kawano, Takahito; Shimomura, Masatsugu; Yabu, Hiroshi

2013-04-25

427

Pentamines as substrate for human spermine oxidase  

PubMed Central

Substrate activities of various linear polyamines to human spermine oxidase (hSMO) were investigated. The activities were evaluated by monitoring the amount of H2O2 released from sample polyamines by hSMO. H2O2 was measured by a HPLC method that analyzed fluorescent dimers derived from the oxidation of homovanillic acid in the presence of horseradish peroxidase. Six triamines were tested and were found not to be hSMO substrates. Of sixteen tetramines tested, spermine (Spm) was the most active substrate, followed by homospermine and N-butylated Spm. Pentamines showed a characteristic pattern of substrate activity. Of thirteen pentamines tested, 3343 showed higher substrate activity than Spm, and 4343 showed similar activity to Spm. The activities of the other pentamines were as follows: 3443, 4443, 4344, 3344, 4334, 4444, and 3334 (in decreasing order). Product amines released from these pentamines by hSMO were then analyzed by HPLC. Triamine was the only observed product, and the amount of triamine was nearly equivalent to that of released H2O2. A marked difference in the pH dependency curves between tetramines and pentamines suggested that hSMO favored reactions with a non-protonated secondary nitrogen at the cleavage site. The Km and Vmax values for Spm and 3343 at pH 7.0 and 9.0 were consistent with the higher substrate activity of 3343 compared to Spm, as well as with the concept of a non-protonated secondary nitrogen at the cleavage site being preferred, and 3343 was well degraded at a physiological pH by hSMO. PMID:23449327

Takao, Koichi; Shirahata, Akira; Samejima, Keijiro; Casero, Robert A.; Igarashi, Kazuei; Sugita, Yoshiaki

2013-01-01

428

The inhibition of monoamine oxidase by esomeprazole.  

PubMed

Virtual screening of a library of drugs has suggested that esomeprazole, the S-enantiomer of omeprazole, may possess binding affinities for the active sites of the monoamine oxidase (MAO) A and B enzymes. Based on this finding, the current study examines the MAO inhibitory properties of esomeprazole. Using recombinant human MAO-A and MAO-B, IC50 values for the inhibition of these enzymes by esomeprazole were experimentally determined. To examine the reversibility of MAO inhibition by esomeprazole, the recoveries of the enzymatic activities after dilution of the enzyme-inhibitor complexes were evaluated. In addition, reversibility of inhibition was also examined by measuring the recoveries of enzyme activities after dialysis of enzyme-inhibitor mixtures. Lineweaver-Burk plots were constructed to evaluate the mode of MAO inhibition and to measure Ki values. The results document that esomeprazole inhibits both MAO-A and MAO-B with IC50 values of 23 µM and 48 µM, respectively. The interactions of esomeprazole with MAO-A and MAO-B are reversible and most likely competitive with Ki values for the inhibition of the respective enzymes of 8.99 µM and 31.7 µM. Considering the available pharmacokinetic data and typical therapeutic doses of esomeprazole, these inhibitory potencies are unlikely to be of pharmacological relevance in humans. The MAO inhibitory effects of esomeprazole should however be taken into consideration when using this drug in animal experiments where higher doses are often administered. PMID:23677700

Petzer, A; Pienaar, A; Petzer, J P

2013-09-01

429

Hydrogen Production by Co-cultures of Rhizopus oryzae and a Photosynthetic Bacterium, Rhodobacter sphaeroides RV  

NASA Astrophysics Data System (ADS)

Hydrogen production with glucose by using co-immobilized cultures of a fungus, Rhizopus oryzae NBRC5384, and a photosynthetic bacterium, Rhodobacter sphaeroides RV, in agar gels was studied. The co-immobilized cultures converted glucose to hydrogen via lactate in a high molar yield of about 8moles of hydrogen per glucose at a maximum under illuminated conditions.

Asada, Yasuo; Ishimi, Katsuhiro; Nagata, Yoko; Wakayama, Tatsuki; Miyake, Jun; Kohno, Hideki

430

Expression and characterization of fifteen Rhizopus oryzae 99-880 polygalacturonase enzymes in Pichia pastoris  

Technology Transfer Automated Retrieval System (TEKTRAN)

Polygalacturonase enzymes hydrolyze the long polygalacturonic acid chains found in the smooth regions of pectin. Interest in this enzyme class continues due to their ability to macerate tissues of economically important crops and their use in a number of industrial processes. Rhizopus oryzae has a l...

431

Enhancement of the Stability of a Prolipase from Rhizopus oryzae toward Aldehydes by Saturation Mutagenesis  

Microsoft Academic Search

A prolipase from Rhizopus oryzae (proROL) was engineered in order to increase its stability toward lipid oxidation products such as aldehydes with the aim of improving its performance in oleochemical industries. Out of 22 amino acid residues (15 Lys and 7 His) prone to react with aldehydes, 6 Lys and all His residues (except for the catalytic histidine) were chosen

Mirella Di Lorenzo; Aurelio Hidalgo; Rafael Molina; Juan A. Hermoso; Domenico Pirozzi; Uwe T. Bornscheuer

2007-01-01

432

DEVELOPMENT OF 2,240 NEW SSR MARKERS FOR RICE (ORYZA SATIVA)  

Technology Transfer Automated Retrieval System (TEKTRAN)

A total of 2,417 new di-, tri- and tetra-nucleotide SSR markers, representing 2,243 unique loci have been developed and experimentally validated for rice (Oryza sativa L.). Duplicate primer pairs are reported for 7% (174) of the loci. The majority (92%) of primer pairs were developed in regions flan...

433

LACTIC ACID PRODUCTION BY SACCHAROMYCES CEREVISIAE EXPRESSING A RHIZOPUS ORYZAE LACTATE DEHYDROGENASE GENE  

Technology Transfer Automated Retrieval System (TEKTRAN)

This work demonstrates the first example of a fungal LDH expressed in yeast. A L(+)-lactate dehydrogenase gene, ldhA, from the filamentous fungus Rhizopus oryzae was modified to be expressed under control of the Saccharomyces cerevisiae adhl promoter and terminator, then placed in a 2 micron contai...

434

Sequencing of Aspergillus nidulans and comparative analysis with A. fumigatus and A. oryzae  

Microsoft Academic Search

The aspergilli comprise a diverse group of filamentous fungi spanning over 200 million years of evolution. Here we report the genome sequence of the model organism Aspergillus nidulans, and a comparative study with Aspergillus fumigatus, a serious human pathogen, and Aspergillus oryzae, used in the production of sake, miso and soy sauce. Our analysis of genome structure provided a quantitative

James E. Galagan; Sarah E. Calvo; Christina Cuomo; Li-Jun Ma; Jennifer R. Wortman; Serafim Batzoglou; Su-In Lee; Meray Bastürkmen; Christina C. Spevak; John Clutterbuck; Vladimir Kapitonov; Jerzy Jurka; Claudio Scazzocchio; Mark Farman; Jonathan Butler; Seth Purcell; Steve Harris; Gerhard H. Braus; Oliver Draht; Silke Busch; Christophe D'Enfert; Christiane Bouchier; Gustavo H. Goldman; Deborah Bell-Pedersen; Sam Griffiths-Jones; John H. Doonan; Jaehyuk Yu; Kay Vienken; Arnab Pain; Michael Freitag; Eric U. Selker; David B. Archer; Miguel Á. Peńalva; Berl R. Oakley; Michelle Momany; Toshihiro Tanaka; Toshitaka Kumagai; Kiyoshi Asai; Masayuki Machida; William C. Nierman; David W. Denning; Mark Caddick; Michael Hynes; Mathieu Paoletti; Reinhard Fischer; Bruce Miller; Paul Dyer; Matthew S. Sachs; Stephen A. Osmani; Bruce W. Birren

2005-01-01

435

Construction of six Oryza sativa x O. rufipogon Chromosome Segment Substitution Line (CSSL) Libraries  

Technology Transfer Automated Retrieval System (TEKTRAN)

Transgressive variation has been observed in rice (Oryza sativa) as an increase in grain yield and attributed to the ancestral parent, O. rufipogon, in mapping populations developed from several adapted rice varieties crossed with a single O. rufipogon accession. To explore this phenomenon of transg...

436

Cyclic nucleotide binding proteins in the Arabidopsis thaliana and Oryza sativa genomes  

Microsoft Academic Search

Cyclic nucleotides are ubiquitous intracellular messengers. Until recently, the roles of cyclic nucleotides in plant cells have proven difficult to uncover. With an understanding of the protein domains which can bind cyclic nucleotides (CNB and GAF domains) we scanned the completed genomes of the higher plants Arabidopsis thaliana (mustard weed) and Oryza sativa (rice) for the effectors of these signalling

Dave Bridges; Marie E Fraser; Greg B. G. Moorhead

2005-01-01

437

Sheath blight disease screening methods to identify resistant Oryza spp. accessions  

Technology Transfer Automated Retrieval System (TEKTRAN)

Oryza species, wild relatives of cultivated rice (O. sativa), may contain novel resistance genes to sheath blight, caused by Rhizoctonia solani Kühn, that could be used to enhance resistance to this important disease in commercial rice. Suitable greenhouse screening methods are needed to identify re...

438

Induction of salicylic acid-mediated defense response in perennial ryegrass against infection by Magnaporthe oryzae.  

PubMed

Incorporation of plant defense activators is an innovative approach to development of an integrated strategy for the management of turfgrass diseases. The effects of salicylic acid (SA), benzothiadiazole (BTH, chemical analog of SA), jasmonic acid (JA), and ethephon (ET, an ethylene-releasing compound) on development of gray leaf spot in perennial ryegrass (Lolium perenne L.) caused by Magnaporthe oryzae were evaluated. Gray leaf spot disease incidence and severity were significantly decreased when plants were treated prior to inoculation with SA, BTH, and partially by ET but not by JA. Accumulation of endogenous SA and elevated expression of pathogenesis-related (PR)-1, PR-3.1, and PR-5 genes were associated with inoculation of plants by M. oryzae. Treatment of plants with SA enhanced expression levels of PR-3.1 and PR-5 but did not affect the PR-1 level, whereas BTH treatment enhanced relative expression levels of all three PR genes. Microscopic observations of leaves inoculated with M. oryzae revealed higher frequencies of callose deposition at the penetration sites in SA- and BTH-treated plants compared with the control plants (treated with water). These results suggest that early and higher induction of these genes by systemic resistance inducers may provide perennial ryegrass with a substantial advantage to defend against infection by M. oryzae. PMID:24328494

Rahman, Alamgir; Kuldau, Gretchen A; Uddin, Wakar

2014-06-01

439

Genome-wide association mapping reveals rich genetic architecture of complex traits in Oryza sativa  

Technology Transfer Automated Retrieval System (TEKTRAN)

Domesticated Asian rice, Oryza sativa, is a cultivated, inbreeding species that feeds over half of the world’s population. Understanding the genetic basis of diverse physiological, developmental, and morphological traits provides the basis for improving yield, quality and sustainability. Here, we pr...

440

Transcriptome Analysis of Early Responsive Genes in Rice during Magnaporthe oryzae Infection  

PubMed Central

Rice blast disease caused by Magnaporthe oryzae is one of the most serious diseases of cultivated rice (Oryza sativa L.) in most rice-growing regions of the world. In order to investigate early response genes in rice, we utilized the transcriptome analysis approach using a 300 K tilling microarray to rice leaves infected with compatible and incompatible M. oryzae strains. Prior to the microarray experiment, total RNA was validated by measuring the differential expression of rice defense-related marker genes (chitinase 2, barwin, PBZ1, and PR-10) by RT-PCR, and phytoalexins (sakuranetin and momilactone A) with HPLC. Microarray analysis revealed that 231 genes were up-regulated (>2 fold change, p < 0.05) in the incompatible interaction compared to the compatible one. Highly expressed genes were functionally characterized into metabolic processes and oxidation-reduction categories. The oxidative stress response was induced in both early and later infection stages. Biotic stress overview from MapMan analysis revealed that the phytohormone ethylene as well as signaling molecules jasmonic acid and salicylic acid is important for defense gene regulation. WRKY and Myb transcription factors were also involved in signal transduction processes. Additionally, receptor-like kinases were more likely associated with the defense response, and their expression patterns were validated by RT-PCR. Our results suggest that candidate genes, including receptor-like protein kinases, may play a key role in disease resistance against M. oryzae attack. PMID:25506299

Wang, Yiming; Kwon, Soon Jae; Wu, Jingni; Choi, Jaeyoung; Lee, Yong-Hwan; Agrawal, Ganesh Kumar; Tamogami, Shigeru; Rakwal, Randeep; Park, Sang-Ryeol; Kim, Beom-Gi; Jung, Ki-Hong; Kang, Kyu Young; Kim, Sang Gon; Kim, Sun Tae

2014-01-01

441

Monogenic lines resistance to blast disease in rice (Oryza sativa l.) in Vietnam  

Microsoft Academic Search

Blast, caused by Pyricularia grisea Cav., is one of the major fungal diseases infected rice (Oryza sativa L.) in Vietnam. This disease occurs in Vietnam which causes the yield loss of up to 20% particularly in a year with long wet season. Local varieties have been considered as genetic sources of disease resistance among crops. The breeding program was aimed

Nguyen Thi Lang; Trinh thi Luy; Bui Chi Buu

2009-01-01

442

Genetic analysis of rice domestication syndrome with the wild annual species, Oryza nivara  

Microsoft Academic Search

Summary •W ith a small and sequenced genome, rice provides an excellent system for studying the genetics of cereal domestication. •W e conducted a quantitative trait locus (QTL) analysis of key domestication traits using an F 2 population derived from a cross between the cultivated rice, Oryza sativa , and the annual wild species, O. nivara . •W e found

Changbao Li; Ailing Zhou; Tao Sang

2006-01-01

443

Natural variation and evolution of the avirulence genes in Magnaporthe oryzae  

Technology Transfer Automated Retrieval System (TEKTRAN)

The avirulence genes in Magnaporthe oryzae are important determinants for the corresponding resistance genes in rice. In the present study, we analyzed DNA sequence variation of the five avirulence genes, AVR-Pita1, AVR-Pik, AVR-Piz(t), AVR-Pia and AVR-Pii in field blast isolates in order to unders...

444

Characterization of resistance genes to rice blast fungus magnaporthe oryzae in a “Green Revolution” rice variety  

Technology Transfer Automated Retrieval System (TEKTRAN)

The indica rice variety Dee Geo Woo Gen (DGWG) was the source of the semi-dwarf gene (SD1) which played an important role in the Green Revolution. In the present study, resistance (R) genes to the U.S. race (isolate) IB54 of Magnaporthe oryzae, causal agent of rice blast disease, was investigated. T...

445

Genome-wide association mapping reveals a rich genetic architecture of complex traits in Oryza sativa  

Microsoft Academic Search

Asian rice, Oryza sativa is a cultivated, inbreeding species that feeds over half of the world's population. Understanding the genetic basis of diverse physiological, developmental, and morphological traits provides the basis for improving yield, quality and sustainability of rice. Here we show the results of a genome-wide association study based on genotyping 44,100 SNP variants across 413 diverse accessions of

Keyan Zhao; Chih-Wei Tung; Georgia C. Eizenga; Mark H. Wright; M. Liakat Ali; Adam H. Price; Gareth J. Norton; M. Rafiqul Islam; Andy Reynolds; Jason Mezey; Anna M. McClung; Carlos D. Bustamante; Susan R. McCouch

2011-01-01

446

Common and distinct organ and stress responsive transcriptomic patterns in Oryza sativa and Arabidopsis thaliana  

Microsoft Academic Search

BACKGROUND: Arabidopsis thaliana is clearly established as the model plant species. Given the ever-growing demand for food, there is a need to translate the knowledge learned in Arabidopsis to agronomically important species, such as rice (Oryza sativa). To gain a comparative insight into the similarities and differences into how organs are built and how plants respond to stress, the transcriptomes

Reena Narsai; Ian Castleden; James Whelan

2010-01-01

447

Studying Pellet Formation of a Filamentous Fungus Rhizopus oryzae to Enhance Organic Acid Production  

NASA Astrophysics Data System (ADS)

Using pelletized fungal biomass can effectively improve the fermentation performance for most of fugal strains. This article studied the effects of inoculum and medium compositions such as potato dextrose broth (PDB) as carbon source, soybean peptone, calcium carbonate, and metal ions on pellet formation of Rhizopus oryzae. It has been found that metal ions had significantly negative effects on pellet formation whereas soybean peptone had positive effects. In addition PDB and calcium carbonate were beneficial to R. oryzae for growing small smooth pellets during the culture. The study also demonstrated that an inoculum size of less than 1.5×109 spores/L had no significant influence on pellet formation. Thus, a new approach to form pellets has been developed using only PDB, soybean peptone, and calcium carbonate. Meanwhile, palletized fungal fermentation significantly enhanced organic acid production. Lactic acid concentration reached 65.0 g/L in 30 h using pelletized R. oryzae NRRL 395, and fumeric acid concentration reached 31.0 g/L in 96 h using pelletized R. oryzae ATCC 20344.

Liao, Wei; Liu, Yan; Chen, Shulin

448

AZOSPIRA ORYZAE (A SELENIUM OXYANION-REDUCING BACTERIUM) 16S RRNA GENE COMPLETE SEQUENCE.  

Technology Transfer Automated Retrieval System (TEKTRAN)

This study used 1535 base pair 16S rRNA gene sequence methods to confirm the identification of a bacterium that reduces selenite to elemental red selenium as Azospira oryzae. Morphological and biochemical characteristics are consistent with the 16S rRNA gene sequence identification of the bacterium....

449

Effect of Saccharomyces cerevisiae or Aspergillus oryzae cultures and NDF level on parameters of ruminal fermentation  

Microsoft Academic Search

A metabolism trial was conducted to study the effect of two direct-fed microbial cultures (Saccharomyces cerevisiae, SC; Aspergillus oryzae, AO) and neutral detergent fibre (NDF) level on ruminal fermentation. Six ruminally fistulated Holstein heifers (300 kg body weight) were randomly assigned to a 6 × 6