Multiple‐Site Concerted Proton−Electron Transfer in a Manganese‐Based Complete Functional Model for the [FeFe]‐Hydrogenase

2021 ◽  
Author(s):  
Shuanglin He ◽  
Fang Huang ◽  
Qianqian Wu ◽  
Ping zhang ◽  
ying xiong ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Functional Model ◽  
Multiple Site

Multiple‐Site Concerted Proton−Electron Transfer in a Manganese‐Based Complete Functional Model for the [FeFe]‐Hydrogenase

2021 ◽  
Author(s):  
Shuanglin He ◽  
Fang Huang ◽  
Qianqian Wu ◽  
Ping zhang ◽  
ying xiong ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Functional Model ◽  
Multiple Site

A tetracopper(II) complex as a functional model of multi-copper proteins mediates an efficient four-electron transfer to O2 in an aerobic oxidation of catechols

2003 ◽  
Vol 96 (1) ◽  
pp. 198
Author(s):  
Jun Nakazawa ◽  
Tomohisa Kawata ◽  
Masahito Kodera ◽  
Koji Kano
Keyword(s):  
Electron Transfer ◽  
Aerobic Oxidation ◽  
Functional Model ◽  
Copper Proteins

scholarly journals On the Mechanism of Electrochemical Generation and Decomposition of Phthalimide N-oxyl (PINO)

2021 ◽  
Author(s):  
Cheng Yang ◽  
Luke Farmer ◽  
Derek Pratt ◽  
Stephen Maldonado ◽  
Corey Stephenson
Keyword(s):  
Electron Transfer ◽  
Hydrogen Atom ◽  
Catalytic Efficiency ◽  
Hydrogen Atom Transfer ◽  
Second Order ◽  
Atom Transfer ◽  
Multiple Site ◽  
Mechanistic Studies ◽  
Electrochemical Generation ◽  
Bulk Electrolysis

Phthalimide <i>N</i>-oxyl (PINO) is a potent hydrogen atom transfer (HAT) catalyst that can be generated electrochemically from <i>N</i>-hydroxyphthalimide (NHPI). However, catalyst decomposition has limited its application. This paper details mechanistic studies of the generation and decomposition of PINO under electrochemical conditions. Voltammetric data, observations from bulk electrolysis, and <a>computational</a> studies suggest two primary aspects. First, base-promoted formation of PINO from NHPI occurs via multiple-site concerted proton-electron transfer (MS-CPET). Second, PINO decomposition occurs by at least two second-order paths, one of which is greatly enhanced by base. Optimal catalytic efficiency in PINO-catalyzed oxidations occurs in the presence of bases whose corresponding conjugate acids have <a>p<i>K</i><sub>a</sub></a>s in the range of 12-15, which strike a balance between promoting PINO formation and minimizing its decay.

scholarly journals Multiple-Site Concerted Proton–Electron Transfer Reactions of Hydrogen-Bonded Phenols Are Nonadiabatic and Well Described by Semiclassical Marcus Theory

2012 ◽  
Vol 134 (40) ◽  
pp. 16635-16645 ◽  
Author(s):  
Joel N. Schrauben ◽  
Mauricio Cattaneo ◽  
Thomas C. Day ◽  
Adam L. Tenderholt ◽  
James M. Mayer
Keyword(s):  
Electron Transfer ◽  
Marcus Theory ◽  
Transfer Reactions ◽  
Multiple Site ◽  
Electron Transfer Reactions ◽  
Hydrogen Bonded

scholarly journals On the Mechanism of Electrochemical Generation and Decomposition of Phthalimide N-oxyl (PINO)

2021 ◽  
Author(s):  
Cheng Yang ◽  
Luke Farmer ◽  
Derek Pratt ◽  
Stephen Maldonado ◽  
Corey Stephenson
Keyword(s):  
Electron Transfer ◽  
Hydrogen Atom ◽  
Catalytic Efficiency ◽  
Hydrogen Atom Transfer ◽  
Second Order ◽  
Atom Transfer ◽  
Multiple Site ◽  
Mechanistic Studies ◽  
Electrochemical Generation ◽  
Bulk Electrolysis

Phthalimide <i>N</i>-oxyl (PINO) is a potent hydrogen atom transfer (HAT) catalyst that can be generated electrochemically from <i>N</i>-hydroxyphthalimide (NHPI). However, catalyst decomposition has limited its application. This paper details mechanistic studies of the generation and decomposition of PINO under electrochemical conditions. Voltammetric data, observations from bulk electrolysis, and <a>computational</a> studies suggest two primary aspects. First, base-promoted formation of PINO from NHPI occurs via multiple-site concerted proton-electron transfer (MS-CPET). Second, PINO decomposition occurs by at least two second-order paths, one of which is greatly enhanced by base. Optimal catalytic efficiency in PINO-catalyzed oxidations occurs in the presence of bases whose corresponding conjugate acids have <a>p<i>K</i><sub>a</sub></a>s in the range of 12-15, which strike a balance between promoting PINO formation and minimizing its decay.

A light optical diffractometer for electron microscopical images operating in line

1978 ◽  
Vol 36 (1) ◽  
pp. 86-87
Author(s):  
P. Bonhomme ◽  
A. Beorchia
Keyword(s):  
Electron Microscopy ◽  
Electron Transfer ◽  
Electron Microscope ◽  
Image Converter ◽  
Coherent Light ◽  
Spatial Filters ◽  
Electron Image ◽  
Electron Microscopical ◽  
Working Parameters ◽  
Amorphous Part

We have already described (1.2.3) a device using a pockel's effect light valve as a microscopical electron image converter. This converter can be read out with incoherent or coherent light. In the last case we can set in line with the converter an optical diffractometer. Now, electron microscopy developments have pointed out different advantages of diffractometry. Indeed diffractogram of an image of a thin amorphous part of a specimen gives information about electron transfer function and a single look at a diffractogram informs on focus, drift, residual astigmatism, and after standardizing, on periods resolved (4.5.6). These informations are obvious from diffractogram but are usualy obtained from a micrograph, so that a correction of electron microscope parameters cannot be realized before recording the micrograph. Diffractometer allows also processing of images by setting spatial filters in diffractogram plane (7) or by reconstruction of Fraunhofer image (8). Using Electrotitus read out with coherent light and fitted to a diffractometer; all these possibilities may be realized in pseudoreal time, so that working parameters may be optimally adjusted before recording a micrograph or before processing an image.

Biological electron-transfer reactions

1999 ◽  
Vol 34 ◽  
pp. 101-124 ◽  
Author(s):  
A. Grant Mauk
Keyword(s):  
Electron Transfer ◽  
Transfer Reactions ◽  
Electron Transfer Reactions ◽  
Biological Electron Transfer

Flavin radicals, conformational sampling and robust design principles in interprotein electron transfer: the trimethylamine dehydrogenase-electron-transferring flavoprotein complex

2004 ◽  
Vol 71 ◽  
pp. 1-14
Author(s):  
David Leys ◽  
Jaswir Basran ◽  
François Talfournier ◽  
Kamaldeep K. Chohan ◽  
Andrew W. Munro ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Kinetic Studies ◽  
Molecular Assembly ◽  
Conformational Sampling ◽  
Trimethylamine Dehydrogenase ◽  
Key Residues ◽  
Electron Transferring Flavoprotein ◽  
Electron Transfer Complex

TMADH (trimethylamine dehydrogenase) is a complex iron-sulphur flavoprotein that forms a soluble electron-transfer complex with ETF (electron-transferring flavoprotein). The mechanism of electron transfer between TMADH and ETF has been studied using stopped-flow kinetic and mutagenesis methods, and more recently by X-ray crystallography. Potentiometric methods have also been used to identify key residues involved in the stabilization of the flavin radical semiquinone species in ETF. These studies have demonstrated a key role for 'conformational sampling' in the electron-transfer complex, facilitated by two-site contact of ETF with TMADH. Exploration of three-dimensional space in the complex allows the FAD of ETF to find conformations compatible with enhanced electronic coupling with the 4Fe-4S centre of TMADH. This mechanism of electron transfer provides for a more robust and accessible design principle for interprotein electron transfer compared with simpler models that invoke the collision of redox partners followed by electron transfer. The structure of the TMADH-ETF complex confirms the role of key residues in electron transfer and molecular assembly, originally suggested from detailed kinetic studies in wild-type and mutant complexes, and from molecular modelling.

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