When the details do really matter

To physicists details don't matter. To chemists they do and to biologists they are a matter of life and death. The key question in understanding biomolecular structure, property, and function is: which details really do matter.

The Figure above is taken from a fascinating PNAS paper which I will post about later on. But this post is just to point out an important point illustrated by the Figure. It shows the location of different amino acids (Glu194, Ser193, etc..) inside the protein bacteriorhodopsin. Each different colour corresponds to the location determined and published by a different experimental group. To a physicist the differences look pretty minor. However, it turns out the exact distance between the oxygen atoms at the end of the Glu194 and Glu204 residues turn out to be crucial for understanding where proton involved in the protein-pump function of the protein is stored.
A second more general point is that the different structures illustrate that one should always take published protein crystal structures with a healthy skepticism.