Re: [chimerax-users] Align command; designating the positions to align

LOL, make that "Good point"!! Darn multitasking. :-) Elaine

On Jul 18, 2022, at 2:42 PM, Elaine Meng via ChimeraX-users wrote:

God point. Also, if you use matchmaker, it will do a sequence alignment and figure out which numbers go with which (so you don't have to give residue ranges at all, unless you want to restrict it). Matchmaker will only use the alpha-carbons, though. Align will give you more precise control over exactly which residues are used and allow you to use all backbone atoms if you want.

There is both a Matchmaker GUI (tool) and a command. https://rbvi.ucsf.edu/chimerax/docs/user/tools/matchmaker.html https://rbvi.ucsf.edu/chimerax/docs/user/commands/matchmaker.html

Elaine

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On Jul 18, 2022, at 2:38 PM, Smith, Harper E. wrote:

Hi Phil,

Another solution would be to use MatchMaker instead. Instead of the command you tried, use: mmaker #1:11-323 to #2:24-336 In my experience, MatchMaker is quite powerful.

Best, Harper From: ChimeraX-users on behalf of Elaine Meng via ChimeraX-users Sent: Monday, July 18, 2022 5:33 PM To: McClean, Phillip Cc: chimerax-users@cgl.ucsf.edu Subject: Re: [chimerax-users] Align command; designating the positions to align

Hi Phil, Your syntax is fine if you really meant to specify all atoms of the residues. Most likely reasons for the error are:

(1) the residue types are not identical, so they contain different numbers of atoms (e.g. tryptophan has many more atoms than alanine) (2) one structure or the other is missing some residues from the coordinates (e.g. a flexible loop was not resolved from density) (3) one structure or the other has multiple chains so you are getting residues with those numbers from more than one chain (e.g. chain A has residues 11-323 but so does chain B)

Another possible problem is that there is no underscore in the "toAtoms" option keyword. You can truncate it to "to" if you like.

<https://urldefense.com/v3/__https://rbvi.ucsf.edu/chimerax/docs/user/command... >

Assuming it is the first one, the solution is to specify matching only backbone atoms, or only alpha-carbons. Whichever you would like the RMSD to reflect. You would use an @ symbol to specify atom names. So it may be something like

align #1:11-323@n,ca,c,o to #2:24-336@n,ca,c,o

...for all backbone atoms, or for alpha-carbons only:

align #1:11-323@ca to #2:24-336@ca

<https://urldefense.com/v3/__https://rbvi.ucsf.edu/chimerax/docs/user/command... >

I hope this helps, Elaine ----- Elaine C. Meng, Ph.D. UCSF Chimera(X) team Department of Pharmaceutical Chemistry University of California, San Francisco

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On Jul 18, 2022, at 2:22 PM, McClean, Phillip via ChimeraX-users wrote:

Hi,

I have been trying to properly code the align command. I would like to use the command to determine the RMSD value between corresponding sections of two highly homologous proteins. Here are the details:

Model 1 is to be aligned to Model 2; each model only has one chain Model 1 positions (residues=amino acids) 11-323 Model 2 positions ( residues=amino acids) 24-336

When I pair each of the amino acids that are being aligned, everyone of the pairs has the same number of atoms.

Here is what I thought would work:

align #1:11-323 to_atoms #2:24-336

Here is the error message:

Unequal number of atoms to pair, 2483 to 2371

I am still trying to understand the nomenclature for understanding residues and atoms.

Thanks for any help you can provide.

Phil McClean

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