Polarization in proteins

Dear All,
 I am interested in calculating polarization effects (changes in partial
 charges) on conformational changes in proteins. I know that there are
 many potentials for polarizable water (and other small molecules) models
 but I am looking for a (preferably free) program/forcefield that uses
 electonegativity equalization method and is parametrized for proteins.
 I would also be grateful for any links to relevant papers.
 Thank you in advance