Dependence of Rate Constants of an Electron-Transfer Reaction on the Optical Configuration of the Reactants

1966 ◽  
Vol 88 (2) ◽  
pp. 373-373 ◽  
Author(s):  
Walter Bruning ◽  
S. I. Weissman
Keyword(s):  
Electron Transfer ◽  
Rate Constants ◽  
Transfer Reaction ◽  
Electron Transfer Reaction ◽  
Optical Configuration

scholarly journals A method for extracting rate constants from initial rates of stopped-flow kinetic data: application to a physiological electron-transfer reaction

1993 ◽  
Vol 294 (1) ◽  
pp. 211-213 ◽  
Author(s):  
H B Brooks ◽  
V L Davidson
Keyword(s):  
Electron Transfer ◽  
Rate Constants ◽  
Kinetic Data ◽  
Transfer Reaction ◽  
Dissociation Constants ◽  
Accurate Method ◽  
Electron Transfer Reaction ◽  
Stopped Flow ◽  
Methylamine Dehydrogenase ◽  
Substrate Complex

The most commonly used methods for analysis of stopped-flow kinetic data require performing a series of measurements in which one reactant is varied at concentrations significantly greater than the concentration of the other reactant. For enzyme-catalysed reactions this may not be possible, because the dissociation constants for the enzyme-substrate complex are often of the same order of magnitude as the high concentrations of enzyme that must frequently be used in stopped-flow studies. An alternative method of data analysis is presented which allows the determination of microscopic rate constants from initial rates of stopped-flow kinetic data in which substrate is varied in a range of concentrations approximately the same as the enzyme. This method also provides a simple and accurate method for determining k4, the rate of the reverse reaction. This method has been used to describe a physiological electron transfer reaction between a quinoprotein, methylamine dehydrogenase, and a copper protein, amicyanin. At 20 degrees C, the rate of the electron-transfer reaction from methylamine dehydrogenase to amicyanin was 24 s-1, and the dissociation constant for complex-formation was 1.9 microM.

Effects of potassium ion on the electron-transfer reaction between Fe(CN)64− and TCNQ or chloranil

1978 ◽  
Vol 56 (16) ◽  
pp. 2216-2220 ◽  
Author(s):  
Sadayuki Matsuda ◽  
Akihiko Yamagishi
Keyword(s):  
Electron Transfer ◽  
Rate Constants ◽  
Transfer Reaction ◽  
Temperature Jump ◽  
Ion Pairing ◽  
Electron Transfer Reaction ◽  
Potassium Ion ◽  
The Other ◽  
Transfer Reactions ◽  
Forward Rate

The effects of potassium ion on the electron-transfer reactions between Fe(CN)64− and 7,7,8,8-tetracyanoquinodimethane (TCNQ) or chloranil (QCl4) were studied with temperature-jump equipment; [Formula: see text]. The solvent was a 1:1 (v/v) mixture of acetonitrile–water. In both Systems, the forward rate constants (kr) were unaffected by the addition of KCl; kf(Fe(CN)64−/TCNQ) = (2.9 ± 0.2) × 106 M−1 s−1, and kr(Fe(CN)64−/QCl4) = (5.2 ± 0.4) × 104 M−1 s−1 On the other hand, the backward rate constants (kb) increased with the increase of the KCl concentration. The results are interpreted in terms of ion-pairing equilibria of Fe(CN)64− and Fe(CN)63−.

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