It has been known since the mid-90s that redox enzymes, and in particular hydrogenases, can exchange electrons with certain electrodes while retaining the catalytic properties that fascinate biologists and chemists alike. This can be exploited in two different ways, which we address in the course of the seminar.
Firstly, it is possible to use the configuration in which the enzyme is adsorbed onto an electrode to measure its activity (the number of dihydrogen molecules oxidized per second) via an electric current. This method offers many advantages over traditional activity measurements, and enables us to address certain aspects of the mechanism that are very difficult to study using conventional techniques. We are implementing this novel approach to enzyme kinetics in a multidisciplinary context, which also includes the contributions of directed mutagenesis and the use of magnetic spectroscopies. We illustrate this by presenting some recent results concerning the catalytic mechanism of various hydrogenases, and also the reasons why they cease to function in the presence of dioxygen.
A second, more applied, aspect is that these adsorbed enzymes could be used to replace the precious metal-based supported catalysts present in bio-technological devices that either produce dihydrogen or oxidize it to generate electricity. The sensitivity of hydrogenases to oxygen is one of the obstacles to be overcome.
Electrochemical studies enable us to select the enzymes best suited to these applications, and to envisage their rational optimization by genetic engineering techniques.
Further information, bibliography and teaching materials :
http://bip.cnrs-mrs.fr/bip06/index.fr.htm
