Effects of Mutations in Plastocyanin on the Kinetics of the Protein Rearrangement Gating the Electron-Transfer Reaction with Zinc Cytochromec. Analysis of the Rearrangement Pathway†

Biochemistry ◽  
1996 ◽  
Vol 35 (51) ◽  
pp. 16465-16474 ◽  
Author(s):  
Milan M. Crnogorac ◽  
Chengyu Shen ◽  
Simon Young ◽  
Örjan Hansson ◽  
Nenad M. Kostić
Keyword(s):  
Electron Transfer ◽  
Transfer Reaction ◽  
Electron Transfer Reaction ◽  
Kinetics Of

Kinetics of Electron Transfer Reaction between Co(II) and Chlorate Ions: Experimental and Modeling Study

2021 ◽  
Vol 43 (5) ◽  
pp. 559-559
Author(s):  
Mahwish Mobeen Khan and Syed Mumtaz Danish Naqvi Mahwish Mobeen Khan and Syed Mumtaz Danish Naqvi
Keyword(s):  
Electron Transfer ◽  
Transfer Reaction ◽  
High Energy ◽  
Electron Transfer Reaction ◽  
Maximum Likelihood Estimates ◽  
Oxidation Catalyst ◽  
Standard Entropy ◽  
Rate Of Reaction ◽  
Kinetics Of ◽  
Activated Complex

This research article reports original experimental and modeling detail of kinetics of the electron transfer reaction between Co(II) and chlorate ions in acetic acid solution. Design of experiment methodology has been employed to elucidate the effects of temperature and initial concentrations of reactants on the rate of reaction. Levenberg-Marquardt method has been used to fit processed kinetic data (temperatures, initial concentrations of reactants, and concentrations and rates of production of Co(III)) on to various possible rate equations. This algorithm provides a proficient mean for compensating the capricious effects of the experimental process variables and results in the maximum likelihood estimates of the kinetic parameters. The most significant rate law has been selected, on the basis of statistical analyses of the residuals between the predicted and experimental rates. The analyses suggest that the intrinsic rate of reaction is proportional to first power of chlorate concentration but for Co(II) the order is fractional (0.7455 ≈ and#190;). The effect of temperature on the observed rate constant (precision = 0.02 %) is excellently described by the Arrhenius and Eyring equations and the sluggish nature of the reaction is clearly manifested by the high energy (andgt; 93 kJ/mol), negative entropy (-28.5286 J/mol-K) and very small equilibrium constant of activation. Further fairly negative standard entropy of activation shows there is usually considerable rearrangement of energy among various degrees of freedom during the formation of activated complex and proposes an associative mechanism for formation of the activated complex. This research is performed to develop a kinetic model for the electron transfer reaction between Co(II) and chlorate ion. As a result, a redox couple of Co(II)/Co(III) has been formed which is used as a potent oxidation catalyst in chemical industries.

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 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.

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