TODO: Atom and Residue Protrusion Calculator


The Cx algorithm by Pintar et al (2002) is used to rapidly calculate the protrusion of atoms. It can also be generalised to apply to the protrusion of residue (or general atom groups).
There are other methods for calculating protrusion, such as the protrusion index by Jones and Thornton (1997), but Cx has largely become the dominant method today.

A function similar to the Cx algorithm or protrusion index should be included in .NET Bio Structure for surface analysis of molecules. This function is frequently used in machine learning and docking applications in computational biochemistry and can be used to judge the importance of other functions of an atom are to peripheral molecules, such as electrostatic potential.