Nature as an example
Hydrogenases, by contrast, are truly green hydrogen catalysts (although brown in color). As enzymes, they are naturally produced by microorganisms and entirely made from earth-abundant elements. However, producing hydrogenases on a large scale has been challenging, primarily because these enzymes must first undergo an activation process. During this activation, the active site - where catalysis takes place - must be stably embedded into the protein scaffold, a process that is difficult for some hydrogenases.
Unfortunately, for one of the most promising hydrogenases, this activation step is exceptionally slow. Scientists from the Professorship for Electrobiotechnology at TUM Campus Straubing for Biotechnology and Sustainability, together with their collaboration partners, have now discovered that this is due to the high flexibility of the part of the protein scaffold that holds the active site. Due to this high flexibility, the scaffold is unable to readily close and stably hold the inserted active site in place.
Optimizing what is provided by nature for energy systems
To overcome this problem, the researchers re-engineered the hydrogenase by fusing the two subunits that together form the active enzyme. They designed and tested different linkers that connect the ends of the subunits, thereby reducing the protein scaffold’s flexibility and enabling a faster scaffold closure around the active site. With this optimized enzyme design, the required time for the activation process is reduced by a factor of 40.
These advances remove a major obstacle to the large-scale production of this highly efficient, platinum-free hydrogen catalyst and have recently been published in the journal Chemical Science.