scholarly journals Characterization of 12-Oxophytodienoic Acid Reductases from Rose-scented Geranium (Pelargonium graveolens)

2016 ◽  
Vol 11 (12) ◽  
pp. 1934578X1601101
Author(s):  
Miu Iijima ◽  
Hiromichi Kenmoku ◽  
Hironobu Takahashi ◽  
Jung-Bum Lee ◽  
Masao Toyota ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Metabolic Engineering ◽  
Double Bond ◽  
Carbonyl Compound ◽  
Catalytic Properties ◽  
Biotechnological Applications ◽  
Pelargonium Graveolens ◽  
Double Bond Reductase ◽  
Herbal Plant

Pelargonium graveolens L'Hér, also referred to as rose geranium, is a popular herbal plant with typical rosy fragrance largely based on the blend of monoterpenoid constituents. Among them, citronellol, which is biosynthesized from geraniol via double bond reduction, is the most abundant scent compound. In this study, three 12-oxophytodienoic acid reductases (PgOPR1–3) have been cloned from P. graveolens, as possible candidates for the double-bond reductase involved in citronellol biosynthesis. The bacterially expressed recombinant PgOPRs did not reduce geraniol to citronellol, but stereoselectively converted citral into ( S)-citronellal in the presence of NADPH. Thus, the α,β-unsaturated carbonyl moiety in the substrate is essential for the catalytic activity of PgOPRs, as reported for OPRs from other plants and structurally related yeast old yellow enzymes. PgOPRs promiscuously accepted linear and cyclic α,β-unsaturated carbonyl substrates, including methacrolein, a typical reactive carbonyl compound. The possible biotechnological applications for PgOPRs in plant metabolic engineering, based on their catalytic properties, are discussed herein.

scholarly journals Biocatalytic Asymmetric Alkene Reduction: Crystal Structure and Characterization of a Double Bond Reductase from Nicotiana tabacum

ACS Catalysis ◽  
2013 ◽  
Vol 3 (3) ◽  
pp. 370-379 ◽  
Author(s):  
David J. Mansell ◽  
Helen S. Toogood ◽  
John Waller ◽  
John M. X. Hughes ◽  
Colin W. Levy ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Double Bond ◽  
Nicotiana Tabacum ◽  
Double Bond Reductase

scholarly journals Selective Hydration of Nitriles to Corresponding Amides in Air with Rh(I)-N-Heterocyclic Complex Catalysts

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 125 ◽  
Author(s):  
Csilla Enikő Czégéni ◽  
Sourav De ◽  
Antal Udvardy ◽  
Nóra Judit Derzsi ◽  
Gergely Papp ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Solid State ◽  
Nmr Spectroscopy ◽  
Catalytic Properties ◽  
13C Nmr Spectroscopy ◽  
Synthetic Method ◽  
X Ray Diffraction ◽  
Nitrile Hydration ◽  
X Ray

A new synthetic method for obtaining [RhCl(cod)(NHC)] complexes (1–4) (cod = η4-1,5-cyclooctadiene, NHC = N-heterocyclic carbene: IMes, SIMes, IPr, and SIPr, respectively) is reported together with the catalytic properties of 1–4 in nitrile hydration. In addition to the characterization of 1–4 in solution by 13C NMR spectroscopy, the structures of complexes 3, and 4 have been established also in the solid state with single-crystal X-ray diffraction analysis. The Rh(I)-NHC complexes displayed excellent catalytic activity in hydration of aromatic nitriles (up to TOF = 276 h−1) in water/2-propanol (1/1 v/v) mixtures in air.

Characterization of the catalytic activity of the membrane-anchored metalloproteinase ADAM15 in cell-based assays

2009 ◽  
Vol 420 (1) ◽  
pp. 105-113 ◽  
Author(s):  
Thorsten Maretzky ◽  
Guangli Yang ◽  
Ouathek Ouerfelli ◽  
Christopher M. Overall ◽  
Susanne Worpenberg ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Cancer Metastasis ◽  
Phorbol Esters ◽  
Catalytic Properties ◽  
Growth Factor Receptor ◽  
Ectodomain Shedding ◽  
Intact Cells ◽  
Peptide Substrates ◽  
Prostate Cancer Metastasis

ADAM15 (a disintegrin and metalloproteinase 15) is a membrane-anchored metalloproteinase, which is overexpressed in several human cancers and has been implicated in pathological neovascularization and prostate cancer metastasis. Yet, little is known about the catalytic properties of ADAM15. Here, we purified soluble recombinant ADAM15 to test for its ability to cleave a library of peptide substrates. However, we found no processing of any of the peptide substrates tested here, and therefore turned to cell-based assays to characterize the catalytic properties of ADAM15. Overexpression of full-length membrane-anchored ADAM15 or the catalytically inactive ADAM15E→A together with various membrane proteins resulted in increased release of the extracellular domain of the fibroblast growth factor receptor 2iiib (FGFR2iiib) by ADAM15, but not ADAM15E→A. This provided a robust assay for a characterization of the catalytic properties of ADAM15 in intact cells. We found that increased expression of ADAM15 resulted in increased FGFR2iiib shedding, but that ADAM15 was not stimulated by phorbol esters or calcium ionophores, two commonly used activators of ectodomain shedding. Moreover, ADAM15-dependent processing of FGFR2iiib was inhibited by the hydroxamate-based metalloproteinase inhibitors marimastat, TAPI-2 and GM6001, and by 50 nM TIMP-3 (tissue inhibitor of metalloproteinases 3), but not by 100 nM TIMP-1, and only weakly by 100 nM TIMP-2. These results define key catalytic properties of ADAM15 in cells and its response to stimulators and inhibitors of ectodomain shedding. A cell-based assay for the catalytic activity of ADAM15 could aid in identifying compounds, which could be used to block the function of ADAM15 in pathological neovascularization and cancer.

The Preparation and Characterization of Carbon Nanostructures Catalyst and its Catalytic Activity

2011 ◽  
Vol 418-420 ◽  
pp. 629-632
Author(s):  
Huan Ying Li ◽  
Shu Li Bai ◽  
Wen Ping Jia ◽  
Fang Li
Keyword(s):  
Catalytic Activity ◽  
Carbon Nanostructures ◽  
Catalytic Properties ◽  
Catalytic Reduction ◽  
Catalyst Support ◽  
High Catalytic Activity ◽  
Single Structure ◽  
Catalytic Functions ◽  
Pure Surface

In this work, the constructing of different carbon nanostructures materials were studied, and the single-structure and pure surface of carbon nanostructures were employed to as catalyst support and the morphology and structure of different carbon nanostructures-based catalysts were investigated. NO catalytic reduction was used as a probe reaction to investigate the catalytic properties of different carbon nanostructures materials and how the controlling of carbon nanostructures would affect its catalytic functions. The results show that vanadium was molecularly anchored on the surface of carbon nanostructures and the mesh-carbon nanotubes as a support show a high catalytic activity.

Characterization and Acid Catalytic Properties of NiO Supported on ZrO2 and Modified with MoO3

2007 ◽  
Vol 124-126 ◽  
pp. 1797-1800 ◽  
Author(s):  
Jong Rack Sohn ◽  
Dong Cheol Shin
Keyword(s):  
Aqueous Solution ◽  
Catalytic Activity ◽  
Acid Catalysis ◽  
Catalytic Properties ◽  
Orthorhombic Phase ◽  
Acid Strength ◽  
Two Dimensional ◽  
Ammonium Heptamolybdate ◽  
Cumene Dealkylation

Nickel oxide supported on zirconia and modified with MoO3 for acid catalysis was prepared by drying powdered Ni(OH)2-Zr(OH)4 with ammonium heptamolybdate aqueous solution, followed by calcining in air at high temperature. The characterization of prepared catalysts was performed using FTIR, Raman, XRD, and DSC. MoO3 equal to or less than 15 wt% was dispersed on the surface of catalyst as two-dimensional polymolybdate or monomolybdate, while for MoO3 above 15 wt%, crystalline orthorhombic phase of MoO3 was formed. The high acid strength and acidity were responsible for the Mo=O bond nature of the complex formed by the interaction between MoO3 and ZrO2. The catalytic activity for cumene dealkylation was correlated with the acidity of the catalyst measured by the ammonia chemisorption method

Isolation and characterization of AaAER, a novel double bond reductase from Artemisia annua

2014 ◽  
Vol 24 (3) ◽  
pp. 331-337 ◽  
Author(s):  
Yu-Kun Wei ◽  
Jian-Xu Li ◽  
Wen-Li Hu ◽  
Chang-Qing Yang ◽  
Ling-Jian Wang
Keyword(s):  
Double Bond ◽  
Artemisia Annua ◽  
Isolation And Characterization ◽  
Double Bond Reductase

A Pyridinic Fe-N4 Macrocycle Effectively Models the Active Sites in Fe/N-Doped Carbon Electrocatalysts

2020 ◽  
Author(s):  
Travis Marshall-Roth ◽  
Nicole J. Libretto ◽  
Alexandra T. Wrobel ◽  
Kevin Anderton ◽  
Nathan D. Ricke ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Active Sites ◽  
Catalytic Properties ◽  
Reduction Reaction ◽  
Iron Phthalocyanine ◽  
Electrochemical Studies ◽  
Onset Potential ◽  
Nitrogen Doped Carbon ◽  
Iron Active Sites

Iron- and nitrogen-doped carbon (Fe-N-C) materials are leading candidates to replace platinum in fuel cells, but their active site structures are poorly understood. A leading postulate is that iron active sites in this class of materials exist in an Fe-N<sub>4</sub> pyridinic ligation environment. Yet, molecular Fe-based catalysts for the oxygen reduction reaction (ORR) generally feature pyrrolic coordination and pyridinic Fe-N<sub>4</sub> catalysts are, to the best of our knowledge, non-existent. We report the synthesis and characterization of a molecular pyridinic hexaazacyclophane macrocycle, (phen<sub>2</sub>N<sub>2</sub>)Fe, and compare its spectroscopic, electrochemical, and catalytic properties for oxygen reduction to a prototypical Fe-N-C material, as well as iron phthalocyanine, (Pc)Fe, and iron octaethylporphyrin, (OEP)Fe, prototypical pyrrolic iron macrocycles. N 1s XPS signatures for coordinated N atoms in (phen<sub>2</sub>N<sub>2</sub>)Fe are positively shifted relative to (Pc)Fe and (OEP)Fe, and overlay with those of Fe-N-C. Likewise, spectroscopic XAS signatures of (phen<sub>2</sub>N<sub>2</sub>)Fe are distinct from those of both (Pc)Fe and (OEP)Fe, and are remarkably similar to those of Fe-N-C with compressed Fe–N bond lengths of 1.97 Å in (phen<sub>2</sub>N<sub>2</sub>)Fe that are close to the average 1.94 Å length in Fe-N-C. Electrochemical studies establish that both (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe have relatively high Fe(III/II) potentials at ~0.6 V, ~300 mV positive of (OEP)Fe. The ORR onset potential is found to directly correlate with the Fe(III/II) potential leading to a ~300 mV positive shift in the onset of ORR for (Pc)Fe and (phen<sub>2</sub>N<sub>2</sub>)Fe relative to (OEP)Fe. Consequently, the ORR onset for (phen<sub>2</sub>N<sub>2</sub>)Fe and (Pc)Fe is within 150 mV of Fe-N-C. Unlike (OEP)Fe and (Pc)Fe, (phen<sub>2</sub>N<sub>2</sub>)Fe displays excellent selectivity for 4-electron ORR with <4% maximum H<sub>2</sub>O<sub>2</sub> production, comparable to Fe-N-C materials. The aggregate spectroscopic and electrochemical data establish (phen<sub>2</sub>N<sub>2</sub>)Fe as a pyridinic iron macrocycle that effectively models Fe-N-C active sites, thereby providing a rich molecular platform for understanding this important class of catalytic materials.<p><b></b></p>

Decomposition of hydrogen peroxide on a two-component NiO-CdO catalyst and the effect of ionizing radiation on its catalytic properties

1979 ◽  
Vol 44 (4) ◽  
pp. 1015-1022 ◽  
Author(s):  
Viliam Múčka
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Nickel Oxide ◽  
Catalytic Properties ◽  
Cadmium Oxide ◽  
Chemisorb Oxygen ◽  
Composition Region ◽  
Chemisorbed Oxygen ◽  
Two Component

The catalytic properties of two-component catalyst nickel oxide-cadmium oxide with the proportions of the components covering the whole composition region 0-100% were examined by studying the decomposition of hydrogen peroxide in aqueous solution on it. In the range 0-25 mol.% CdO, cadmium oxide is found to affect infavourably the ability of nickel oxide to chemisorb oxygen. The amount of the chemisorbed oxygen increases several times on gamma irradiation of the samples. The effect of cadmium oxide on the catalytic activity of the system shows up in fresh samples only indirectly via the changed amount of the oxygen chemisorbed. In older samples the initial catalytic activity of the system is changed, which can be explained based on the concept of bivalent catalytic centres in terms of the co-action of the catalytic centres of the two oxides, which are in equilibrium. The irradiation of the system under study speeds up the processes leading to the establishing of this equilibrium which is thermally very stable, and results in a substantial increase of the catalytic activity of the samples investigated.

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