[gmx-users] heme topology

[Valentin Gogonea]

Hello gromacs users,

I have a question about how pdb2gmx creates topology for His-Heme group. 
It seems to me that in the .rtp file a bond of type Fe-N(His) is not 
defined for HEME residue, still pdb2gmx creates one. Can anybody explain 
me how this is done? Does pdb2gmx checks for proximity of atoms based on 
distance and uses ffgmxbon.itp file to check for possible bonds?

Thank you for your assistance.

Valentin