The previous post in this series can be found here.
This week, inspired by Shaun's most recent post covering exciting new results in cosmology, I have decided to also take a quick look at one of the fascinating recent findings of molecular biology. I hope to give some insight into how this work is done, and why it is not only intellectually interesting, but also potentially practically useful.
What do we know?
Those of you who have been following this series for a while might remember a post that I wrote last year (biological batteries and motors) where I discuss how energy is converted from myriad chemical forms in your food into the single energy currency of the cell, ATP. The system by which this is achieved is quite beautiful, chemical energy is converted into an electrical current within the mitochondria of your cells, which is in turn converted into a current of protons. This proton current drives a motor (ATP synthase) that churns out ATP, thereby converting it back into chemical energy. I'm not going to go into the whole process again here, but if you'd like a quick refresher then just hop back to my older post here, go on - you know you want to! I don't mind waiting.
So, a key player in this whole process is the so-called respiratory complex I (or NADH dehydrogenase), which is the first link in the chain that converts electrical current into proton current. Complex I takes electrons from a molecule known as NADH, which is produced from energy in your food by a range of complex metabolic chemical reactions. It moves the electrons that it takes from NADH and sticks them onto a molecule called ubiquinone, which then moves on to the next stage in the process: the perhaps confusingly named complex III.