Dear Pankaj, All the methods in Chimera are pairwise, but you can still get a multiple superposition by doing multiple pairwise superpositions. In fact, you can get a multiple superposition in one step using the MatchMaker tool - just choose one structure as the reference and multiple others as the structures to match. Here is the manual page: http://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/matchmaker/ matchmaker.html There is also a "matchmaker" command that works the same way, and a "match" command in which you can specify exactly which atoms should be used; with those, you would need to use the command multiple times (once for each pairwise match). Here are the manual pages for the commands: http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/mmaker.html http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/match.html The "Images for Publication" tutorial includes an example of superimposing 3 structures with either command (go to the "Matching Structures" section): http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/tutorials/ frameimages.html I am not sure what you meant about being unable to perform multiple superposition, so I just listed the ways and where to look for more information. If you still have problems after using this information, it might be an issue with your structures - if so, you could let us know what the structures are and more details about what you did and what happened in Chimera. I hope this helps, 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 On May 19, 2007, at 6:23 AM, Pankaj Barah wrote:

Dear all, I have been using UCSF Chimera for structural superpositions for last few days. But while trying to do multiple superimposition for a set of proteins, i am unable to perform it. can anybody give me any suggestion? Regards

Pankaj Barah Junior Research Fellow, Phone:+91-9922346120(M) Bioinformatics Centre, +91-20-25692039(O) University of Pune, Pune 411 007,Maharashtra, India.