Mesoporous Electrodes Enhance the Electrocatalytic Performance of [FeFe]-Hydrogenase.

The metalloenzyme [FeFe]-hydrogenase is of interest to future biotechnologies targeting the production of "green" hydrogen (H). We recently developed a simple two-step functionalized procedure to immobilize the [FeFe]-hydrogenase from Clostridium pasteurianum ("CpI") on mesoporous indium tin oxide (ITO) electrodes to achieve elevated H production with high operational stability and current densities of 8 mA cm. Here, we use a combination of atomic force microscopy (AFM), scanning electron microscopy (SEM) and electrochemical quartz crystal microbalance (EQCM) to understand how mesoporous ITO stabilizes and activates CpI for electroenzymatic H production.

Insights into the Molecular Mechanism of Formaldehyde Inhibition of [FeFe]-Hydrogenases.

[FeFe]-hydrogenases are efficient H converting biocatalysts that are inhibited by formaldehyde (HCHO). The molecular mechanism of this inhibition has so far not been experimentally solved. Here, we obtained high-resolution crystal structures of the HCHO-treated [FeFe]-hydrogenase CpI from , showing HCHO reacts with the secondary amine base of the catalytic cofactor and the cysteine C299 of the proton transfer pathway which both are very important for catalytic turnover.