Redox (In)activations of Metalloenzymes: A Protein Film Voltammetry Approach

• Published in: ChemElectroChem Vol. 6; no. 19; pp. 4949 - 4962
• Main Authors: Barrio, Melisa, Fourmond, Vincent
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 01.10.2019; Weinheim : Wiley-VCH
• Subjects: Analytical chemistry; Chemical reactions; Chemical Sciences; Electron transfer; Enzymes; hydrogenases; metalloenzymes; Organic chemistry; Other; protein film voltammetry; Proteins; redox activation; redox inactivation; Voltammetry; Protein Film Voltammetry; redox activation; copper enzymes; hydrogenases; metalloenzymes; redox inactivation; molybdenum enzymes
• ISSN: 2196-0216; 2196-0216
• DOI: 10.1002/celc.201901028

Redox metalloenzymes are omnipresent in living organisms where they catalyze key cellular reactions with great efficiency. These enzymes can often be reversibly placed into inactive states following changes in redox conditions. This is a hindrance for their use in biotechnological devices, and also a complication for their study via a structure/function approach, because structural data alone usually is not enough to discriminate between active and inactive states. However, these inactive states can also inform on the chemistry of the enzyme's active sites and on their catalytic cycles. A technique that has proved particularly valuable in the last decades for studying these processes is protein film voltammetry (PFV), in which an enzyme is immobilized on an electrode in a configuration where direct electron transfer is possible. In this article, we review the studies of redox (in)activation processes using PFV, present the theory for a number of cases (reversible inactivations, irreversible activations), and give guidelines to obtain and interpret suitable kinetic data. To be or not to be active: Redox metalloenzymes are often the subject of inactivation and reactivation processes triggered by changes in redox states. These processes show as significant hysteresis in cyclic voltammetry of immobilized enzymes. Here, we show how one can use direct electrochemistry to study these processes and review the latest advances in this field.