Thank you for your help. I did superimpose the structure with pdv viewer. I did save as a pdb file but when I open the morph conformations tool and I add the pdb I am not able to create the interpolation between the structure.

Do you know why?

Hi Djemel, I would recommend just using Chimera to superimpose the structures. Starting with the two structures in two separate files, open them with File... Open in the Chimera menu, then superimpose them. There are lots of ways to superimpose them but probably this simple command (show command line with Favorites... Command Line) will work fine: matchmaker #0 #1 In Morph Conformations you have to specify more than one structure. There should be more than one line in the Conformations list. My guess (and it's only a guess) is that the way the other program wrote the file it was considered all one structure, not 2 separate structures. Best, Elaine ----- Elaine C. Meng, Ph.D. meng@cgl.ucsf.edu UCSF Computer Graphics Lab and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco http://www.cgl.ucsf.edu/home/meng/index.html