scholarly journals Nonenzymatic NADH-Dependent Reduction of Keggin-Type 12-Tungstocobaltate(III) in Aqueous Medium

2011 ◽  
Vol 8 (3) ◽  
pp. 1152-1157
Author(s):  
Prabla Kumari ◽  
Alaka Das ◽  
Dillip Kumar Baral ◽  
A. K. Pattanaik ◽  
P. Mohanty
Keyword(s):  
Electron Transfer ◽  
Transition State ◽  
Aqueous Medium ◽  
Transfer Reaction ◽  
Activation Parameters ◽  
Electron Transfer Reaction ◽  
Transfer Reactions ◽  
Electron Transfer Reactions ◽  
First Order ◽  
Kinetics Of

The kinetics of the electron transfer reaction of NADH with 12-tungstocobaltate(III) has been studied over the range 5.07 ≤ 104[NADH] ≤ 15.22 mol dm-3, 7.0 ≤ pH ≤ 8.0 and 20 ≤ t ≤ 35oC in aqueous medium. The electron transfer reaction showed first-order dependence each in [NADH]Tand [12-tungstocobaltate(III)]T. The products of the reaction were found to be NAD+and 12-tungstocobaltate(II). The activation parameters ΔH#(kJ mol-1) and ΔS#(JK-1mol-1) of the electron transfer reactions were found to be 64.4±1.8 and -48.86±6.0. Negative value of ΔS#is an indicative of an ordered transition state for the electron transfer reaction.

scholarly journals Non enzymatic NADH-dependent reduction of Cis-[Co(en)2(H2O)2]3+ in aqueous medium

2018 ◽  
Vol 6 (2) ◽  
pp. 163
Author(s):  
Bharati Behera ◽  
Jashoda Behera
Keyword(s):  
Electron Transfer ◽  
Aqueous Medium ◽  
Transfer Reaction ◽  
Activation Parameters ◽  
Electron Transfer Reaction ◽  
Transfer Reactions ◽  
Electron Transfer Reactions ◽  
First Order ◽  
Order Dependence ◽  
Kinetics Of

The kinetics of the electron transfer reaction of NADH with Cis-[Co(en)2(H2O)2]3+ has been studied over the range 1.0 ≤ 102 [NADH] ≤ 3.0 mol dm-3, 7.0 ≤ pH ≤ 8.0 and 200C ≤ t ≤ 350C in aqueous medium. The rate of electron transfer reaction was found to be first-order dependence each in [NADH]T and Cis-[Co(en)2(H2O)2]3+T. The products of the reaction were found to be NAD+ and Co(II). The corresponding activation parameters of the electron transfer reactions were found to be as ΔH#=27.55 kJ mol-1 and  ΔS#= -189.35 JK-1mol-1. 

Electron-transfer reactions in non-aqueous media. II. Reduction of CoF(NH3)52+, CoCl(NH3)52+ and CoBr(NH3)52+ by iron(II) in dimethyl sulphoxide-water mixtures

1976 ◽  
Vol 29 (1) ◽  
pp. 97 ◽  
Author(s):  
BA Matthews ◽  
DW Watts
Keyword(s):  
Electron Transfer ◽  
Aqueous Media ◽  
Activation Parameters ◽  
Solvent Composition ◽  
Dimethyl Sulphoxide ◽  
Transfer Reactions ◽  
Octahedral Coordination ◽  
Electron Transfer Reactions ◽  
Kinetics Of

The kinetics of the reduction of the cobalt(111) octahedral complexes, CoF(NH3)52+, CoCl(NH3)52+ and CoBr(NH3)52+, by iron((11) in various Me2SO-H2O mixtures have been studied over a range of temperatures. The activation parameters obtained for the chloro and bromo systems are consistent with a change in the stereochemistry of the iron (11) atom in the bridged intermediate from octahedral in water to tetrahedral with increasing Me2SO concentration. The fluoro system, however, has activation parameters which are less sensitive to solvent composition and consistent with the iron(11) atom maintaining octahedral coordination.

scholarly journals Vanadium nitrogenase of Azotobacter chroococcum. MgATP-dependent electron transfer within the protein complex

1989 ◽  
Vol 257 (3) ◽  
pp. 789-794 ◽  
Author(s):  
R N F Thorneley ◽  
N H J Bergström ◽  
R R Eady ◽  
D J Lowe
Keyword(s):  
Electron Transfer ◽  
Transfer Reaction ◽  
Competitive Inhibitor ◽  
Electron Transfer Reaction ◽  
Azotobacter Chroococcum ◽  
First Order ◽  
Fe Protein ◽  
Vanadium Nitrogenase ◽  
Electron Transfer Complex ◽  
Kinetics Of

The kinetics of MgATP-induced electron transfer from the Fe protein (Ac2V) to the VFe protein (AclV) of the vanadium-containing nitrogenase from Azotobacter chroococcum were studied by stopped-flow spectrophotometry at 23 degrees C at pH 7.2. They are very similar to those of the molybdenum nitrogenase of Klebsiella pneumoniae [Thorneley (1975) Biochem. J. 145, 391-396]. Extrapolation of the dependence of kobs. on [MgATP] to infinite MgATP concentration gave k = 46 s-1 for the first-order electron-transfer reaction that occurs with the Ac2V MgATPAclV complex. MgATP binds with an apparent KD = 230 +/- 10 microM and MgADP acts as a competitive inhibitor with Ki = 30 +/- 5 microM. The Fe protein and VFe protein associate with k greater than or equal to 3 x 10(7) M-1.s-1. A comparison of the dependences of kobs. for electron transfer on protein concentrations for the vanadium nitrogenase from A. chroococcum with those for the molybdenum nitrogenase from K. pneumoniae [Lowe & Thorneley (1984) Biochem. J. 224, 895-901] indicates that the proteins of the vanadium nitrogenase system form a weaker electron-transfer complex.

scholarly journals Electron transfer studies of a conventional redox probe in human sweat and saliva bio-mimicking conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
P. Krishnaveni ◽  
V. Ganesh
Keyword(s):  
Electron Transfer ◽  
Crystalline Phase ◽  
Liquid Crystalline ◽  
Transfer Reaction ◽  
Electron Transfer Reaction ◽  
Redox Couple ◽  
Liquid Crystalline Phase ◽  
Transfer Reactions ◽  
Redox Probe ◽  
Human Sweat

AbstractModern day hospital treatments aim at developing electrochemical biosensors for early diagnosis of diseases using unconventional human bio-fluids like sweat and saliva by monitoring the electron transfer reactions of target analytes. Such kinds of health care diagnostics primarily avoid the usage of human blood and urine samples. In this context, here we have investigated the electron transfer reaction of a well-known and commonly used redox probe namely, potassium ferro/ferri cyanide by employing artificially simulated bio-mimics of human sweat and saliva as unconventional electrolytes. Typically, electron transfer characteristics of the redox couple, [Fe(CN)6]3−/4− are investigated using electrochemical techniques like cyclic voltammetry and electrochemical impedance spectroscopy. Many different kinetic parameters are determined and compared with the conventional system. In addition, such electron transfer reactions have also been studied using a lyotropic liquid crystalline phase comprising of Triton X-100 and water in which the aqueous phase is replaced with either human sweat or saliva bio-mimics. From these studies, we find out the electron transfer reaction of [Fe(CN)6]3−/4− redox couple is completely diffusion controlled on both Au and Pt disc shaped electrodes in presence of sweat and saliva bio-mimic solutions. Moreover, the reaction is partially blocked by the presence of lyotropic liquid crystalline phase consisting of sweat and saliva bio-mimics indicating the predominant charge transfer controlled process for the redox probe. However, the rate constant values associated with the electron transfer reaction are drastically reduced in presence of liquid crystalline phase. These studies are essentially carried out to assess the effect of sweat and saliva on the electrochemistry of Fe2+/3+ redox couple.

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