Electron-Transfer Characteristics of the Prosthetic Group of Hemoproteins

1967 ◽  
Vol 89 (7) ◽  
pp. 1552-1558 ◽  
Author(s):  
Theodore Mark. Bednarski ◽  
Joseph. Jordan
Keyword(s):  
Electron Transfer ◽  
Prosthetic Group ◽  
Transfer Characteristics

scholarly journals Synthesis of an elusive, stable 2-azaallyl radical guided by electrochemical and reactivity studies of 2-azaallyl anions

2021 ◽  
Author(s):  
Grace B. Panetti ◽  
Patrick J. Carroll ◽  
Michael R. Gau ◽  
Brian C. Manor ◽  
Eric J. Schelter ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Electron Donor ◽  
Transfer Characteristics

The super electron donor (SED) capabilities of 2-azaallyl anions has recently been discovered and applied to diverse reactivity; their structures and electron transfer characteristics are reported herein.

scholarly journals Cytochrome c550 from Pseudomonas aeruginosa

1993 ◽  
Vol 289 (1) ◽  
pp. 173-178 ◽  
Author(s):  
P Reichmann ◽  
H Görisch
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Electron Transfer ◽  
Oxygen Consumption ◽  
Electron Transport ◽  
Electron Transport Chain ◽  
Prosthetic Group ◽  
Midpoint Potential ◽  
Transport Chain ◽  
Ethanol Dehydrogenase ◽  
Soluble C

In cells of Pseudomonas aeruginosa A.T.C.C. 17933 grown on ethanol the synthesis of a soluble c-type cytochrome, together with quinoprotein ethanol dehydrogenase, is induced. The cytochrome, with an alpha-absorption band at 550 nm, was purified to homogeneity. The molecular mass of the monomeric protein is 15 kDa, the pI is 4.8, and it contains one haem prosthetic group. The midpoint potential of the autoxidizable, but not autoreducible, cytochrome is 280 mV. Cytochrome c550 mediates electron transfer between quinoprotein ethanol dehydrogenase and ferricyanide. In a system composed of membrane particles with NN‘NN’-tetramethyl-p-phenylenediamine oxidase activity and quinoprotein ethanol dehydrogenase, oxygen consumption is only observed in the presence of cytochrome c550. This indicates the participation of the cytochrome in the electron-transport chain linked to quinoprotein ethanol dehydrogenase in P. aeruginosa. The electron transport from ethanol dehydrogenase to oxygen is inhibited by myxothiazol and antimycin, indicating that a cytochrome bc1-like complex is involved.

Synthesis and Electron Transfer Characteristics of a Neutral, Low-Band-Gap, Mixed-Valence Polyradical

2010 ◽  
Vol 22 (24) ◽  
pp. 6641-6655 ◽  
Author(s):  
Dörte Reitzenstein ◽  
Tatjana Quast ◽  
Florian Kanal ◽  
Martin Kullmann ◽  
Stefan Ruetzel ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Band Gap ◽  
Mixed Valence ◽  
Low Band Gap ◽  
Transfer Characteristics

scholarly journals Three-ComponentO-Demethylase System Essential for Catabolism of a Lignin-Derived Biphenyl Compound in Sphingobium sp. Strain SYK-6

2014 ◽  
Vol 80 (23) ◽  
pp. 7142-7153 ◽  
Author(s):  
Taichi Yoshikata ◽  
Kazuya Suzuki ◽  
Naofumi Kamimura ◽  
Masahiro Namiki ◽  
Shojiro Hishiyama ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Reductase Activity ◽  
Normal Growth ◽  
Prosthetic Group ◽  
Gene Encoding ◽  
Content Type ◽  
Sequence Identities ◽  
Electron Transfer Component

ABSTRACTSphingobiumsp. strain SYK-6 is able to assimilate lignin-derived biaryls, including a biphenyl compound, 5,5′-dehydrodivanillate (DDVA). Previously,ligXa(SLG_07770), which is similar to the gene encoding oxygenase components of Rieske-type nonheme iron aromatic-ring-hydroxylating oxygenases, was identified to be essential for the conversion of DDVA; however, the genes encoding electron transfer components remained unknown. Disruption of putative electron transfer component genes scattered through the SYK-6 genome indicated that SLG_08500 and SLG_21200, which showed approximately 60% amino acid sequence identities with ferredoxin and ferredoxin reductase of dicambaO-demethylase, were essential for the normal growth of SYK-6 on DDVA. LigXa and the gene products of SLG_08500 (LigXc) and SLG_21200 (LigXd) were purified and were estimated to be a trimer, a monomer, and a monomer, respectively. LigXd contains FAD as the prosthetic group and showed much higher reductase activity toward 2,6-dichlorophenolindophenol with NADH than with NADPH. A mixture of purified LigXa, LigXc, and LigXd converted DDVA into 2,2′,3-trihydroxy-3′-methoxy-5,5′-dicarboxybiphenyl in the presence of NADH, indicating that DDVAO-demethylase is a three-component monooxygenase. This enzyme requires Fe(II) for its activity and is highly specific for DDVA, with aKmvalue of 63.5 μM andkcatof 6.1 s−1. Genome searches in six other sphingomonads revealed genes similar toligXcandligXd(>58% amino acid sequence identities) with a limited number of electron transfer component genes, yet a number of diverse oxygenase component genes were found. This fact implies that these few electron transfer components are able to interact with numerous oxygenase components and the conserved LigXc and LigXd orthologs are important in sphingomonads.

Effect of Gold Nanoparticles on the Structure and Electron-Transfer Characteristics of Glucose Oxidase Redox Polyelectrolyte-Surfactant Complexes

2014 ◽  
Vol 20 (41) ◽  
pp. 13366-13374 ◽  
Author(s):  
M. Lorena Cortez ◽  
Waldemar Marmisollé ◽  
Diego Pallarola ◽  
Lía I. Pietrasanta ◽  
Daniel H. Murgida ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Electron Transfer ◽  
Glucose Oxidase ◽  
Transfer Characteristics

scholarly journals Kinetic analysis of metsulphmyoglobin and metmyoglobin reduction by Fe(EDTA)2-

1985 ◽  
Vol 229 (3) ◽  
pp. 765-769 ◽  
Author(s):  
A R Lim ◽  
A G Mauk
Keyword(s):  
Electron Transfer ◽  
Ph Dependence ◽  
Activation Parameters ◽  
Reduction Reaction ◽  
Exchange Chromatography ◽  
Central Metal Atom ◽  
Central Metal ◽  
Prosthetic Group ◽  
Point Reduction ◽  
Relative Electron

Metsulphmyoglobin prepared from horse heart myoglobin was purified by ion-exchange chromatography to yield a product that on reduction with Fe(EDTA)2- has an A617/A561 ratio greater than 3.5:1. The kinetics of reduction of this purified metsulphmyoglobin and of native metmyoglobin by Fe(EDTA)2- were studied under various conditions of pH, ionic strength and temperature to compare the relative electron-transfer reactivities of a metallochlorin and a metalloporphyrin in identical protein environments. Although the rate of metsulphmyoglobin reduction is 2-7 times that of metmyoglobin under a variety of conditions, this difference can be more than compensated for by the reported difference in mid-point reduction potential between the two forms of the protein. The electrostatic and activation parameters observed for native metmyoglobin and metsulphmyoglobin are essentially identical, and small differences are found in the pH-dependence of the reduction reaction. These findings lead us to conclude that conversion of the porphyrin prosthetic group into a chlorin has relatively little effect on the electron-transfer reactivity of the central metal atom.

scholarly journals Direct detection of a globin-derived radical in leghaemoglobin treated with peroxides

1992 ◽  
Vol 281 (1) ◽  
pp. 197-201 ◽  
Author(s):  
M J Davies ◽  
A Puppo
Keyword(s):  
Electron Transfer ◽  
Initial Level ◽  
Direct Detection ◽  
Root Nodules ◽  
Phenoxyl Radical ◽  
Radical Scavengers ◽  
Subsequent Reaction ◽  
Prosthetic Group ◽  
Hydroxyl Radical Scavengers ◽  
Compound Ii

The root nodules of leguminous plants contain an oxygen-carrying protein which is somewhat similar to myoglobin. Reaction of the Fe3+ form of this protein (metleghaemoglobin; MetLb) with H2O2 is known to generate a ferryl [iron(IV)-oxo] species. This intermediate, which is analogous to Compound II of peroxidases and ferryl myoglobin, is one oxidizing equivalent above the initial level. In the present study it is shown that the second oxidizing equivalent from the peroxide is rapidly transferred into the surrounding protein, generating a protein radical which has been detected by e.p.r. spectroscopy; this reaction is analogous to that observed with metmyoglobin. An identical protein-derived species is observed with all three forms of MetLb tested (a, c1, c3) and with a number of other hydroperoxides and two-electron oxidants. This latter result, the observation that the concentration of this species is not affected by certain hydroxyl-radical scavengers, and the loss of the radical when the oxy or deoxy forms are used, demonstrate that this species is formed by electron transfer within the protein rather than by the generation and subsequent reaction of hydroxyl radicals (and related species from the other hydroperoxides). The e.p.r. signal of this species, which decays rapidly with a half-life of approx. 40 s, is consistent with the formation of a sterically constrained tyrosine-derived phenoxyl radical; protein-iodination experiments lend support to this assignment. Reaction between the radical and a number of other compounds has been observed, demonstrating that it is at least partially exposed on the surface of the protein. Analysis of the protein structure suggest that the radical may be centred on a tyrosine residue present at position 132 in the protein; this residue is close to the haem prosthetic group, which would facilitate rapid electron transfer.

Interactive influences of decolorized metabolites on electron-transfer characteristics of microbial fuel cells

2016 ◽  
Vol 109 ◽  
pp. 297-304 ◽  
Author(s):  
Lian-Jie Qin ◽  
Ke Han ◽  
Pei-Lin Yueh ◽  
Chuan-Chung Hsueh ◽  
Bor-Yann Chen
Keyword(s):  
Electron Transfer ◽  
Fuel Cells ◽  
Microbial Fuel Cells ◽  
Transfer Characteristics
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