[gmx-users] Inserting water to active site

[hnam]

In the name of God
Hello everyone 
I want to put a water at active site my protein and constraint it near Zn.I 
made one gro file that it contains protein and water with proper coordinate 
but I don't know how to correct top file.
May I ask who to correct top file.
Thank you very much in advance
Institute of  Biochemistry  and  Biophysics (IBB)
Tehran University 
P.O.box 1417614411
Tehran 
Iran