I mentioned a couple days ago that I still have one more presentation and one more paper to finish before I'm done with the semester. Today, I spent a lot of time figuring out how I'm going to proceed for that project, and I decided I'd write about the sensing applications of the α-hemolysin molecule.
Ribbon representations of the α-hemolysin heptamer . Click to enlargeOn the right, you can see a couple images of the α-hemolysin molecule (a top view and a side view), which basically looks like a hollow mushroom. Using a specific chemical process, it is possible to insert this molecule into a membrane, like a cell wall, so that the hollow part of the mushroom provides a sort of tunnel from one side to the other.
Once the tunnel is established, a probe can be pushed through it, and the probe can sense what sort of molecules are on the other side of the membrane. This is important for distinguishing DNA molecules that are different by, for example, only one base pair, which has significant implications for a number of biophysical applications. If you want to read all about it, ask me for a copy of my paper next week. Meanwhile, enjoy the pretty pictures.
Since I've been reading a million articles on these transmembrane sensing applications all day, I think it's about time to order some pizza or some Chinese food or something. I haven't done any grocery shopping in about a week, and I've eaten just about every meal since then at home, so my kitchen is pretty poorly supplied at the moment. My neighbor wants me to put some Christmas lights up tomorrow (perhaps to complement the giant, inflatable, light-up Tigger and Pooh display on his front porch — if you live in Pittsburgh, you need to cruise down Phillips Ave. and see this monstrosity some time), so maybe I'll get some groceries while I'm out buying lights.
Anyway, it's pizza time!
 L. Song, M. R. Hobaugh, C. Shustak, S. Cheley, H. Bayley, and J. E. Gouaux, "Structure of staphylococcal α-hemolysin, a heptameric transmembrane pore," Science, vol. 274, pp. 1859-1866, 1996.