Protonation states in I-TASSER

Dear all,

I have found out a strange thing when I run a standalone I-TASSER. When I have changed in the template the name of histidine from HSE (proton in the epsilon-position) on HSD or HSP, I found a great reduction of model quality (RMSD increased from 3.0 to 4.5). What can be the reason of such a strange behaviour?

Best wishes,
Dmitrii.