In a recent blog post Pat Walters nicely used the structures of Viagra and Cialis when bound to PDE5 to argue that scaffold hopping between these two drugs was not a task that could be performed easily. He used Python to demonstrate that each drug interacted with siginificantly different parts of the protein and that they only shared interactions with 4 residues. Inspired by this, I sought (with the help of Paolo Tosco) to implement Pat’s code in Flare.
Paolo has been working on the implementation of a Jupyter notebook within Python (see his post here) and this provides the ideal environment to implement and discuss code to explore the common and specific interactions of Cialis and Viagra with PDE5. The notebook contents are shown in the iframe below.
As you see the output (last line) is the same as originally reported. However, with the addition of the Flare interface we are able to create a nice visual representation of the results, rendering the common and ligand specific residues differently. The script takes around a 30 seconds to run: