Kinetics of Protoporphyrinogen Oxidase Inhibition by Diphenyleneiodonium Derivatives†

Biochemistry ◽  
1997 ◽  
Vol 36 (33) ◽  
pp. 10178-10184 ◽  
Author(s):  
Sylvain Arnould ◽  
Jean-Luc Berthon ◽  
Cathy Hubert ◽  
Marylène Dias ◽  
Christian Cibert ◽  
...  
Keyword(s):  
Protoporphyrinogen Oxidase ◽  
Oxidase Inhibition ◽  
Kinetics Of

scholarly journals Kinetic studies on protoporphyrinogen oxidase inhibition by diphenyl ether herbicides

1991 ◽  
Vol 277 (1) ◽  
pp. 17-21 ◽  
Author(s):  
J M Camadro ◽  
M Matringe ◽  
R Scalla ◽  
P Labbe
Keyword(s):  
Methyl Ester ◽  
Diphenyl Ether ◽  
Kinetic Studies ◽  
Inhibition Kinetics ◽  
Mitochondrial Membranes ◽  
Protoporphyrinogen Oxidase ◽  
Nitrobenzoic Acid ◽  
Diphenyl Ethers ◽  
Oxidase Inhibition ◽  
Kinetics Of

Diphenyl ethers (DPEs) and related herbicides are powerful inhibitors of protoporphyrinogen oxidase, an enzyme involved in the biosynthesis of haems and chlorophylls. The inhibition kinetics of protoporphyrinogen oxidase of various origins by four DPEs, (methyl)-5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid (acifluorfen and its methyl ester, acifluorfen-methyl), methyl-5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-chlorobenzoate (LS 820340) and methyl-5-[2-chloro-5-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid (RH 5348), were studied. The inhibitions of the enzymes from maize (Zea mays) mitochondrial and etiochloroplastic membranes and mouse liver mitochondrial membranes were competitive with respect to the substrate, protoporphyrinogen IX, for all four molecules. The relative efficiencies of the inhibitors were: acifluorfen-methyl greater than LS 820340 much greater than RH 5348 greater than or equal to acifluorfen. The four molecules showed mixed-competitive type inhibition of the enzyme from yeast mitochondria where acifluorfen, a carboxylic acid, had the same inhibitory activity as its methyl ester, acifluorfen-methyl, and both were much greater than that of LS 820340 and RH 5348.

Molecular Aspects of Herbicide Action on Protoporphyrinogen Oxidase

1993 ◽  
Vol 48 (3-4) ◽  
pp. 326-333 ◽  
Author(s):  
Beate Nicolaus ◽  
Gerhard Sandmann ◽  
Peter Böger
Keyword(s):  
Diphenyl Ether ◽  
Protoporphyrin Ix ◽  
Protoporphyrinogen Oxidase ◽  
Relative Specificity ◽  
Oxidase Inhibition ◽  
Dilution Experiments ◽  
Membrane Bound ◽  
The Common ◽  
Molecular Aspects ◽  
Derivatives Of

Abstract Protoporphyrinogen oxidase, the last enzyme of the common tetrapyrrole biosynthetic pathway, is inhibited by several peroxidizing compounds resulting in accumulation of photodynamic tetrapyrroles, mainly protoporphyrin IX. The inhibition characteristics of two chemi­cally unrelated compounds were studied using membrane bound protoporphyrinogen oxidase from corn etioplasts. As shown by Lineweaver-Burk-analysis, the inhibition of enzyme activity by the diphenyl ether oxyfluorfen and the cyclic imide MCI 15 are competitive with respect to the substrate. The competitive interaction of protoporphyrinogen and the two chemically un­related inhibitors indicate a relative specificity of the binding site. The reversibility of oxyfluorfen inhibition was evaluated by dilution experiments and was shown to be independent of the presence of DTT. The analysis of structure-activity-relationship on protoporphyrinogen oxidase inhibition was investigated with para-substituted derivatives of phenyl-3,4,5,6-tetrahydro-phthalimides. The results obtained by QSAR -calculation yielded a good correlation of the inhibitory activity determined by the lipophilicity of the para-substituent. These data point to one binding region of the inhibitors within a lipophilic environment associated with the active center of the enzyme.

The kinetics of monoamine oxidase inhibition by three 2-indolylmethylamine derivatives

1990 ◽  
Vol 40 (3) ◽  
pp. 535-543 ◽  
Author(s):  
M.Angeles Cruces ◽  
Carlos Elorriaga ◽  
Eldiberto Fernández-Alvarez
Keyword(s):  
Monoamine Oxidase ◽  
Monoamine Oxidase Inhibition ◽  
Oxidase Inhibition ◽  
Kinetics Of

Correlation of protoporphyrinogen oxidase inhibition byO-phenyl pyrrolidino- and piperidino-carbamates with their herbicidal effects

1992 ◽  
Vol 35 (3) ◽  
pp. 227-235 ◽  
Author(s):  
Ujjana B. Nandihalli ◽  
Timothy D. Sherman ◽  
Mary V. Duke ◽  
James D. Fisher ◽  
Vincent A. Musco ◽  
...  
Keyword(s):  
Protoporphyrinogen Oxidase ◽  
Oxidase Inhibition

scholarly journals Protoporphyrinogen oxidase inhibition by three peroxidizing herbicides: Oxadiazon, LS 82-556 and M&B 39279

FEBS Letters ◽  
1989 ◽  
Vol 245 (1-2) ◽  
pp. 35-38 ◽  
Author(s):  
Michel Matringe ◽  
Jean-Michel Camadro ◽  
Pierre Labbe ◽  
René Scalla
Keyword(s):  
Protoporphyrinogen Oxidase ◽  
Oxidase Inhibition

Direct observations of radiation-enhanced transformations in glass

1983 ◽  
Vol 41 ◽  
pp. 354-355
Author(s):  
J. F. DeNatale ◽  
D. G. Howitt
Keyword(s):  
Glass Matrix ◽  
Diffusion Mechanism ◽  
Bubble Formation ◽  
Silicate Glasses ◽  
Phase Decomposition ◽  
Direct Observations ◽  
Thin Foils ◽  
Oxygen Bubble ◽  
Electron Energy Loss ◽  
Kinetics Of

The electron irradiation of silicate glasses containing metal cations produces various types of phase separation and decomposition which includes oxygen bubble formation at intermediate temperatures figure I. The kinetics of bubble formation are too rapid to be accounted for by oxygen diffusion but the behavior is consistent with a cation diffusion mechanism if the amount of oxygen in the bubble is not significantly different from that in the same volume of silicate glass. The formation of oxygen bubbles is often accompanied by precipitation of crystalline phases and/or amorphous phase decomposition in the regions between the bubbles and the detection of differences in oxygen concentration between the bubble and matrix by electron energy loss spectroscopy cannot be discerned (figure 2) even when the bubble occupies the majority of the foil depth.The oxygen bubbles are stable, even in the thin foils, months after irradiation and if van der Waals behavior of the interior gas is assumed an oxygen pressure of about 4000 atmospheres must be sustained for a 100 bubble if the surface tension with the glass matrix is to balance against it at intermediate temperatures.

Irradiation behavior of pyrolytic silicon carbide

1983 ◽  
Vol 41 ◽  
pp. 72-73
Author(s):  
R. J. Lauf
Keyword(s):  
Silicon Carbide ◽  
Fission Products ◽  
Thermodynamics And Kinetics ◽  
Neutron Fluences ◽  
Fuel Particles ◽  
Sic Coatings ◽  
Irradiation Behavior ◽  
Kinetics Of ◽  
Htgr Fuel

Fuel particles for the High-Temperature Gas-Cooled Reactor (HTGR) contain a layer of pyrolytic silicon carbide to act as a miniature pressure vessel and primary fission product barrier. Optimization of the SiC with respect to fuel performance involves four areas of study: (a) characterization of as-deposited SiC coatings; (b) thermodynamics and kinetics of chemical reactions between SiC and fission products; (c) irradiation behavior of SiC in the absence of fission products; and (d) combined effects of irradiation and fission products. This paper reports the behavior of SiC deposited on inert microspheres and irradiated to fast neutron fluences typical of HTGR fuel at end-of-life.

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

Ion Beam Induced Interfacial Reactions in Molybdenum Thin Films on Silicon

1981 ◽  
Vol 39 ◽  
pp. 162-163
Author(s):  
L. J. Chen ◽  
L. S. Hung ◽  
J. W. Mayer
Keyword(s):  
Ion Beam ◽  
Chemical Vapor ◽  
Interfacial Reactions ◽  
Practical Applications ◽  
Microelectronic Devices ◽  
Recent Emergence ◽  
Chemical Vapor Deposited ◽  
Atomic Mixing ◽  
Silicon Interface ◽  
Kinetics Of

When an energetic ion penetrates through an interface between a thin film (of species A) and a substrate (of species B), ion induced atomic mixing may result in an intermixed region (which contains A and B) near the interface. Most ion beam mixing experiments have been directed toward metal-silicon systems, silicide phases are generally obtained, and they are the same as those formed by thermal treatment.Recent emergence of silicide compound as contact material in silicon microelectronic devices is mainly due to the superiority of the silicide-silicon interface in terms of uniformity and thermal stability. It is of great interest to understand the kinetics of the interfacial reactions to provide insights into the nature of ion beam-solid interactions as well as to explore its practical applications in device technology.About 500 Å thick molybdenum was chemical vapor deposited in hydrogen ambient on (001) n-type silicon wafer with substrate temperature maintained at 650-700°C. Samples were supplied by D. M. Brown of General Electric Research & Development Laboratory, Schenectady, NY.

In situ study of electron beam-induced chemical vapor deposition of Au in an environmental TEM

1995 ◽  
Vol 53 ◽  
pp. 256-257
Author(s):  
J. Drucker ◽  
R. Sharma ◽  
J. Kouvetakis ◽  
K.H.J. Weiss
Keyword(s):  
Electron Beam ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Quantum Effect ◽  
Line Drawing ◽  
Chemical Vapor ◽  
Environmental Cell ◽  
Engineering Changes ◽  
Kinetics Of

Patterning of metals is a key element in the fabrication of integrated microelectronics. For circuit repair and engineering changes constructive lithography, writing techniques, based on electron, ion or photon beam-induced decomposition of precursor molecule and its deposition on top of a structure have gained wide acceptance Recently, scanning probe techniques have been used for line drawing and wire growth of W on a silicon substrate for quantum effect devices. The kinetics of electron beam induced W deposition from WF6 gas has been studied by adsorbing the gas on SiO2 surface and measuring the growth in a TEM for various exposure times. Our environmental cell allows us to control not only electron exposure time but also the gas pressure flow and the temperature. We have studied the growth kinetics of Au Chemical vapor deposition (CVD), in situ, at different temperatures with/without the electron beam on highly clean Si surfaces in an environmental cell fitted inside a TEM column.

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