Agapakis et. al.

My paper, "Insulation of a synthetic hydrogen metabolism circuit in bacteria" just came out in the Journal of Biological Engineering! And it's open access!

We designed a metabolic circuit in bacteria that produces hydrogen (a potentially useful fuel) from natural precursors in the cell. The proteins in our synthetic pathway work to make hydrogen by transferring high-energy electrons from pyruvate, a common metabolite, to protons that are freely floating in the watery cytoplasm. The electrons transfer between the proteins through quantum-mechanical tunneling, which makes hydrogenases and other electron transferring proteins some of the craziest enzymes ever.

This tunneling happens so fast once two electron carrying proteins (of which there are many different types in the cell) hit each other, that it's difficult to make sure that all of the electrons from the original metabolite are getting to hydrogen. While sometimes the analogy between synthetic biology and electronics can be a bit tricky, in this case we really have to "insulate" the "wires" that are transferring electrons by preventing them from connecting to other "wires" and "shorting" the "circuit" (sorry to go overboard with the quotation marks but you get the idea). We tested a bunch of different biological methods to insulate the pathway, and all of them made small but significant improvements in the amount of hydrogen that we could produce. These methods can be used not only to optimize the amounts of hydrogen that we can make biologically, but can be applied to many other synthetic biology circuits that use electron transfer to get things done.