Peter Reimann, Andreas Meyer, and Sebastian Getfert, authors of the article featured on the cover of the September 4 issue of Biophysical Journal, describe the polymer translocation through a membrane pore depicted on the cover. The image is from their article On the Lubensky-Nelson model of polymer translocation through nanopores. Meyer, who is currently working on his diploma thesis in Reimann’s group at Bielefeld University in Germany, composed the image.
The protein pore was drawn using Jmol, an open-source Java viewer for chemical structures, while the remainder of the image was drawn “by hand” employing the open-source vector-graphic software Inkscape.
Meyer further explained the image, saying:
“Given the opportunity to co-author an article while still working on my diploma thesis, I was not aware of all aspects involved. To me, the possibility of expressing ones work in an artistic image did not seem to be part of the experience. It proved to be quite an inspirational process, though, and I hope the outcome may serve as a source of inspiration itself. The beauty of science, perhaps especially in physics, sometimes drowns in its pragmatics. Creating the image, I realized the worth of a different view on otherwise rather serious research, and having it chosen as the cover of Biophysical Journal is a great honor.”
The picture visualizes the process of creating a model for polynucleotide translocation through alpha-Hemolysin protein pore. Details in the structure of the nucleotide chain are omitted, while protein pore and membrane appear as static objects, reduced to their physically most important features.
The system described by our theoretical model (and visualized by the picture) is as follows: Driven by an externally imposed voltage difference, a polynucleotide chain (single stranded DNA or RNA) translocates through an alpha hemolysin pore (from top to bottom). Depending on the type of the nucleotide, distinct distributions of translocation times can be measured, making it possible to distinguish between different polymers. The curve at the top shows a fit of our stochastic model to such an experimentally measured distribution. The two peaks can be assigned to the two possible translocation directions of the polymer chain, namely either with their 3’-end or 5′-end first.
Our recent research efforts can be found at http://www2.physik.unibielefeld.de/condmat_reimann.html