scholarly journals Reliable estimation of the kinetic parameters of redox enzymes by taking into account mass transport towards rotating electrodes in protein film voltammetry experiments

2017 ◽  
Vol 245 ◽  
pp. 1059-1064 ◽  
Author(s):  
Meriem Merrouch ◽  
Jessica Hadj-Saïd ◽  
Christophe Léger ◽  
Sébastien Dementin ◽  
Vincent Fourmond
Biochemistry ◽  
2003 ◽  
Vol 42 (29) ◽  
pp. 8653-8662 ◽  
Author(s):  
Christophe Léger ◽  
Sean J. Elliott ◽  
Kevin R. Hoke ◽  
Lars J. C. Jeuken ◽  
Anne K. Jones ◽  
...  

2020 ◽  
Vol 39 (2) ◽  
pp. 153
Author(s):  
Rubin Gulaboski ◽  
Valentin Mirceski

Protein-film voltammetry (PFV) is considered the simplest methodology to study the electrochemistry of lipophilic redox enzymes in an aqueous environment. By anchoring particular redox enzymes on the working electrode surface, it is possible to get an insight into the mechanism of enzyme action. The PFV methodology enables access to the relevant thermodynamic and kinetic parameters of the enzyme-electrode reaction and enzyme-substrate interactions, which is important to better understand many metabolic pathways in living systems and to delineate the physiological role of enzymes. PFV additionally provides important information which is useful for designing specific biosensors, simple medical devices and bio-fuel cells. In the current review, we focus on some recent achievements of PFV, while presenting some novel protocols that contribute to a better communication between redox enzymes and the working electrode. Insights to several new theoretical models that provide a simple strategy for studying electrode reactions of immobilized enzymes and that enable both kinetic and thermodynamic characterization of enzyme-substrate interactions are also provided. In addition, we give a short overview to several novel voltammetric techniques, derived from the perspective of square-wave voltammetry, which seem to be promising tools for application in PFV.


2003 ◽  
Vol 125 (50) ◽  
pp. 15352-15358 ◽  
Author(s):  
Kondo François Aguey-Zinsou ◽  
Paul V. Bernhardt ◽  
Silke Leimkühler

2007 ◽  
Vol 409 (1) ◽  
pp. 159-168 ◽  
Author(s):  
Andrew J. Gates ◽  
David J. Richardson ◽  
Julea N. Butt

Paracoccus pantotrophus expresses two nitrate reductases associated with respiratory electron transport, termed NapABC and NarGHI. Both enzymes derive electrons from ubiquinol to reduce nitrate to nitrite. However, while NarGHI harnesses the energy of the quinol/nitrate couple to generate a transmembrane proton gradient, NapABC dissipates the energy associated with these reducing equivalents. In the present paper we explore the nitrate reductase activity of purified NapAB as a function of electrochemical potential, substrate concentration and pH using protein film voltammetry. Nitrate reduction by NapAB is shown to occur at potentials below approx. 0.1 V at pH 7. These are lower potentials than required for NarGH nitrate reduction. The potentials required for Nap nitrate reduction are also likely to require ubiquinol/ubiquinone ratios higher than are needed to activate the H+-pumping oxidases expressed during aerobic growth where Nap levels are maximal. Thus the operational potentials of P. pantotrophus NapAB are consistent with a productive role in redox balancing. A Michaelis constant (KM) of approx. 45 μM was determined for NapAB nitrate reduction at pH 7. This is in line with studies on intact cells where nitrate reduction by Nap was described by a Monod constant (KS) of less than 15 μM. The voltammetric studies also disclosed maximal NapAB activity in a narrow window of potential. This behaviour is resistant to change of pH, nitrate concentration and inhibitor concentration and its possible mechanistic origins are discussed.


1998 ◽  
Vol 120 (46) ◽  
pp. 11994-11999 ◽  
Author(s):  
Judy Hirst ◽  
Guy N. L. Jameson ◽  
James W. A. Allen ◽  
Fraser A. Armstrong

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