Radius of Gyration Restraints
A pseudopotential for the radius of gyration allows a restraint for
the overall size of a group of atoms. The radius of gyration is
defined as

(26.1) 
where is atom position, and denotes average over all atoms.
The expected value for this quantity has been emprically determined to be

(26.2) 
where
is the number of residues in a compact globular region.
In the case of elongated structures, residues can be selected in
regional groupings for this restraint. The reference is
Kuszewski, Gronenborn, and Clore (1999).
Subsections
XplorNIH 20231110