scholarly journals MauG catalysis: a tale of ferryl iron, radicals and long distance hopping

2014 ◽  
Vol 70 (a1) ◽  
pp. C312-C312
Author(s):  
Carrie Wilmot ◽  
Erik Yukl ◽  
Lyndal Jensen ◽  
Victor Davidson
Keyword(s):  
Hydrogen Peroxide ◽  
Sole Source ◽  
Compound I ◽  
Methylamine Dehydrogenase ◽  
Long Distance ◽  
Axial Ligation ◽  
Tryptophan Tryptophylquinone ◽  
Autotrophic Bacteria ◽  
Heme Enzyme ◽  
Catalytically Active

Methylamine dehydrogenase (MADH) enables some methylotrophic/autotrophic bacteria to grow on methylamine as a sole source of carbon and energy. MADH catalysis depends on the cofactor tryptophan tryptophylquinone (TTQ) that is a posttranslational modification of two Trp residues in the MADH β-subunit. The maturation of MADH depends on four gene products located in the methylamine utilization (mau) gene cluster. One of these, mauG, encodes a c-type di-heme enzyme that completes synthesis of the TTQ cofactor. The potent oxidant is an unusual bis-Fe(IV) MauG species composed of a ferryl heme (Fe(IV)=O) with an oxidizing equivalent stored as Fe(IV) at the second heme, which has an unusual His, Tyr axial ligation. The bis-Fe(IV) oxidant is formally Fe(V) and equivalent to Compound I. Completion of TTQ to generate active MADH involves long-range electron transfer and a radical hopping mechanism to effect catalysis over a 40 Å distance. The MauG catalyzed reaction occurs in three discrete 2-electron events in a hydrogen peroxide or molecular oxygen (+ reducing equivalents) dependent process. A crystal structure of MauG in complex with its protein substrate, a precursor form of MADH known as preMADH, has been solved. The crystals are catalytically active. The order of the 2-electron chemistry catalyzed by MauG was determined through a series of structures from crystals harvested after different amounts of time following crystallization. Hydrogen peroxide to initiate the reaction was generated by the slow breakdown of polyethylene glycol used in crystallization. These in crystallo data are corroborated by mass spectrometry in solution experiments.

Hydrogen peroxide decomposition on a two-component CuO-Cr2O3 catalyst

1988 ◽  
Vol 53 (8) ◽  
pp. 1636-1646 ◽  
Author(s):  
Viliam Múčka ◽  
Kamil Lang
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Extreme Values ◽  
Catalytic Properties ◽  
Active Components ◽  
Catalytic Systems ◽  
Heterogeneous Catalytic ◽  
Peroxide Decomposition ◽  
Two Component ◽  
Catalytically Active

Some physical and catalytic properties of the two-component copper(II)oxide-chromium(III)oxide catalyst with different content of both components were studied using the decomposition of the aqueous solution of hydrogen peroxide as a testing reaction. It has been found that along to both basic components, the system under study contains also the spinel structure CuCr2O4, chromate washable by water and hexavalent ions of chromium unwashable by water. The soluble chromate is catalytically active. During the first period of the reaction the equilibrium is being established in both homogeneous and heterogeneous catalytic systems. The catalytic activity as well as the specific surface area of the washed solid is a non-monotonous function of its composition. It seems highly probable that the extreme values of both these quantities are not connected with the detected admixtures in the catalytic system. The system under study is very insensitive with regard to the applied doses of gamma radiation. Its catalytic properties are changed rather significantly after the thermal treatment and particularly after the partial reduction to low degree by hydrogen. The observed changes of the catalytic activity of the system under study are very probably in connection with the changes of the valence state of the catalytically active components of the catalyst.

Dual Enzyme-Like Performances of PLGA Grafted Maghemite Nanocrystals and Their Synergistic Chemo/Chemodynamic Treatment for Human Lung Adenocarcinoma A549 Cells

2021 ◽  
Vol 17 (6) ◽  
pp. 1007-1019
Author(s):  
Miao Cui ◽  
Hui-Ru Zhang ◽  
Fan Ouyang ◽  
Yu-Qi Guo ◽  
Rui-Fang Li ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Lung Adenocarcinoma ◽  
Therapeutic Strategy ◽  
A549 Cells ◽  
Inorganic Nanoparticles ◽  
Poly Lactic Acid ◽  
Dual Response ◽  
Catalytically Active ◽  
Endogenous Peroxidase ◽  
Lung Adenocarcinoma A549

In recent years, the emergence of non-toxic but catalytically active inorganic nanoparticles has attracted great attention for cancer treatment, but the therapeutic effect has been affected by the limited reactive oxygen species in tumors. Therefore, the combination of chemotherapy and chemodynamic therapy is regarded as a promising therapeutic strategy. In this paper, we reported the preparation and bioactivity evaluation of poly(lactic acid-co-glycolic acid) (PLGA) grafted-γ-Fe2O3 nanoparticles with dual response of endogenous peroxidase and catalase like activities. Our hypothesis is that PLGAgrafted γ-Fe2O3 nanoparticles could be used as a drug delivery system for the anti-tumor drug doxorubicin to inhibit the growth of lung adenocarcinoma A549 cells; meanwhile, based on its mimic enzyme properties, this kind of nanoparticles could be combined with doxorubicin in the treatment of A549 cells. Our experimental results showed that the PLGAgrafted γ-Fe2O3 nanoparticles could simulate the activity of catalase and decompose hydrogen peroxide into H2O and oxygen in neutral tumor microenvironment, thus reducing the oxidative damage caused by hydrogenperoxide to lung adenocarcinoma A549 cells. In acidic microenvironment, PLGA grafted γ-Fe2O3 nanoparticles could simulate the activity of peroxidase and effectively catalyze the decomposition of hydrogen peroxide to generate highly toxic hydroxyl radicals, which could cause the death of A549 cells. Furthermore, the synergistic effect of peroxidase-like activity of PLGA-grafted γ-Fe2O3 nanoparticles and doxorubicin could accelerate the apoptosisand destruction of A549 cells, thus enhancing the antitumor effect of doxorubicin-loaded PLGA-grafted γ-Fe2O3 nanoparticles. Therefore, this study provides an effective nanoplatform based on dual inorganic biomimetic nanozymes for the treatment of lung cancer.

scholarly journals Formation of Compound I in the Reaction of Native Myoglobins with Hydrogen Peroxide

2000 ◽  
Vol 275 (45) ◽  
pp. 34858-34866 ◽  
Author(s):  
Tsuyoshi Egawa ◽  
Hideo Shimada ◽  
Yuzuru Ishimura
Keyword(s):  
Hydrogen Peroxide ◽  
Compound I

scholarly journals Long-distance apoptotic killing of cells is mediated by hydrogen peroxide in a mitochondrial ROS-dependent fashion

2005 ◽  
Vol 12 (11) ◽  
pp. 1442-1444 ◽  
Author(s):  
O Yu Pletjushkina ◽  
E K Fetisova ◽  
K G Lyamzaev ◽  
O Yu Ivanova ◽  
L V Domnina ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Long Distance ◽  
Mitochondrial Ros

scholarly journals Probing the Oxyferrous and Catalytically Active Ferryl States ofAmphitrite ornataDehaloperoxidase by Cryoreduction and EPR/ENDOR Spectroscopy. Detection of Compound I

2010 ◽  
Vol 132 (42) ◽  
pp. 14995-15004 ◽  
Author(s):  
Roman Davydov ◽  
Robert L. Osborne ◽  
Muralidharan Shanmugam ◽  
Jing Du ◽  
John H. Dawson ◽  
...  
Keyword(s):  
Compound I ◽  
Endor Spectroscopy ◽  
Catalytically Active

scholarly journals Synthesis and catalytic properties of nitrogen-containing carbon nanotubes

2021 ◽  
Vol 12 (2) ◽  
pp. 135-143
Author(s):  
Yu. I. Sementsov ◽  
◽  
O. A. Cherniuk ◽  
S. V. Zhuravskyi ◽  
Wang Bo ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Hydrogen Peroxide ◽  
Photoelectron Spectroscopy ◽  
Direct Synthesis ◽  
Synthesis Method ◽  
Total Content ◽  
Carbon Matrix ◽  
Intensity Increase ◽  
Gravimetric Analysis ◽  
Catalytically Active

Nitrogen-containing carbon nanotubes (CNTs) were synthesized by the CVD method on oxide catalysts of Al-Fe-Mo-O by adding acetonitrile or ethylenediamine to the carbon source (propylene), or completely replacing it, as well as impregnating the original CNTs with urea, followed by heat treatment. The structure of nitrogen-containing CNTs (N-CNT) was characterized by the method of Raman scattering, transmission electron microscopy (TEM), differential thermal and gravimetric analysis (DTA, DTG) and X-ray photoelectron spectroscopy (XPS). The influence of the synthesis method on the number and chemical state of nitrogen heteroatoms in the structure of the carbon matrix is found. According to the TEM, nitrogen-containing CNTs have a characteristic bamboo-like structure, which is less perfect compared to the structure of the original CNTs: the characteristic Raman bands (G and D) are shifted to higher frequencies, their half-width and band D intensity increase relative to G. This is also manifested in the lower thermal stability of nitrogen-containing CNTs. According to the XPS, the direct synthesis of nitrogen-containing CNTs increases the total content of nitrogen atoms and the proportion of pyrrolic and quaternary nitrogen against the background of a significant decrease in the amount of pyridinic form. This can be explained by the fact that nitrogen is evenly distributed throughout the carbon matrix of CNTs, and during nitriding of CNTs with urea, nitrogen is included mainly in the surface layers and defects, because the pyridine form is characteristic of the edge location of the nitrogen atom in the graphene plane.The catalytic effect of multilayer nitrogen-containing carbon nanotubes (N-CNT) on the kinetics of decomposition of hydrogen peroxide in aqueous solutions at different pH values is considered. It is concluded that the method of direct synthesis of nitrogen-containing CNTs allows to obtain more catalytically active carbon nanotubes containing more nitrogen, mainly pyrrolic and quaternary type. It has been found that regardless of the method of synthesis, the maximum catalytic activity in the decomposition of hydrogen peroxide is observed at pH 7.

scholarly journals Use of an Artificial Miniaturized Enzyme in Hydrogen Peroxide Detection by Chemiluminescence

Sensors ◽  
2020 ◽  
Vol 20 (13) ◽  
pp. 3793 ◽  
Author(s):  
Gerardo Zambrano ◽  
Flavia Nastri ◽  
Vincenzo Pavone ◽  
Angela Lombardi ◽  
Marco Chino
Keyword(s):  
Hydrogen Peroxide ◽  
Produced Water ◽  
De Novo ◽  
Potable Reuse ◽  
Hydrogen Peroxide Detection ◽  
Automated Assay ◽  
Heme Enzyme ◽  
Environmentally Safe ◽  
Microplate Reader ◽  
Peroxidase Enzymes

Advanced oxidation processes represent a viable alternative in water reclamation for potable reuse. Sensing methods of hydrogen peroxide are, therefore, needed to test both process progress and final quality of the produced water. Several bio-based assays have been developed so far, mainly relying on peroxidase enzymes, which have the advantage of being fast, efficient, reusable, and environmentally safe. However, their production/purification and, most of all, batch-to-batch consistency may inherently prevent their standardization. Here, we provide evidence that a synthetic de novo miniaturized designed heme-enzyme, namely Mimochrome VI*a, can be proficiently used in hydrogen peroxide assays. Furthermore, a fast and automated assay has been developed by using a lab-bench microplate reader. Under the best working conditions, the assay showed a linear response in the 10.0–120 μM range, together with a second linearity range between 120 and 500 μM for higher hydrogen peroxide concentrations. The detection limit was 4.6 μM and quantitation limits for the two datasets were 15.5 and 186 μM, respectively. In perspective, Mimochrome VI*a could be used as an active biological sensing unit in different sensor configurations.

In vivo generation of hydrogen peroxide by rat kidney cortex and glomeruli

1989 ◽  
Vol 256 (1) ◽  
pp. F158-F164 ◽  
Author(s):  
B. R. Guidet ◽  
S. V. Shah
Keyword(s):  
Hydrogen Peroxide ◽  
Catalase Activity ◽  
Renal Cortex ◽  
Specific Activity ◽  
Rat Kidney ◽  
Kidney Cortex ◽  
Compound I ◽  
Rat Kidney Cortex ◽  
Hydrogen Peroxide Generation

The purpose of this study was to demonstrate in vivo generation of hydrogen peroxide by rat renal cortex and glomeruli. Aminotriazole irreversibly inactivates catalase only in the presence of hydrogen peroxide, and previous studies have shown that aminotriazole-mediated inhibition of catalase is a measure of in vivo changes in the hydrogen peroxide generation. Aminotriazole injected intraperitoneally caused a dose-dependent (0.1-1 g/kg) and a time-dependent (15, 30, 60, 90, 120 min) inhibition of the catalase activity in renal cortex. We confirmed that catalase inactivation by aminotriazole was due to formation of a catalase-hydrogen peroxide intermediate (compound I) because catalase inactivation was prevented by ethanol (2 g/kg), a competitive substrate for compound I. The specific activity of catalase in the glomeruli [0.27 +/- 0.026 k/mg protein (where k is the first-order reaction rate constant), n = 5] was significantly lower than the specific activity in the tubules (1.04 +/- 0.15 k/mg protein, n = 5) obtained from the same rats. The residual catalase activity (RCA) in the glomeruli (0.05 +/- 0.01 k/mg protein) was 19% of control values at 90 min after aminotriazole injection (1 g/kg). Taken together these data provide evidence for in vivo generation of hydrogen peroxide by rat renal cortex and glomeruli under normal conditions. Aminotriazole-mediated inhibition of catalase has been used in previous studies as a measure of in vivo changes in the hydrogen peroxide generation.(ABSTRACT TRUNCATED AT 250 WORDS)

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