[Chimera-users] 答复: 答复: needing help for separating structures
meng at cgl.ucsf.edu
Tue Nov 27 08:57:53 PST 2018
Dear Yu Guo,
Well, ChimeraX is changing every day because it is actively under development. It is faster and better at handling large structures, and has some fancier display options… it is the “next generation” software that we intend will eventually replace Chimera. However, it will be some time before it reaches that goal; Chimera has several analysis or modeling tools that are not (yet) in ChimeraX, and currently ChimeraX features are nearly all commands and very few GUIs. However, ChimeraX has some new features that were never in Chimera, like support for VR and more robust/reliable molecular surface calculations, and improvements of features that were also in Chimera, like morphing molecules.
See ChimeraX advantages summary:
...ChimeraX feature highlights:
...and the “missing features” list in the ChimeraX download page:
Elaine C. Meng, Ph.D.
UCSF Chimera(X) team
Department of Pharmaceutical Chemistry
University of California, San Francisco
> On Nov 27, 2018, at 1:54 AM, Yu Guo <yg2 at kth.se> wrote:
> Dear Elaine,
> Many thanks for your help!
> Yes, it is B that I need! Your way works!
> By the way, what are the main differences in functions between Chimera and ChimeraX?
> 发件人: Elaine Meng <meng at cgl.ucsf.edu>
> 发送时间: 2018年11月26日 23:56
> 收件人: Yu Guo
> 抄送: chimera-users
> 主题: Re: [Chimera-users] 答复: needing help for separating structures
> Hi Yu Guo,
> The PDB file is not needed, since I already spent the time to investigate what was in the mmCIF file, and gave you several example commands to select parts of the structure. If you have selected atoms, you can use the Actions menu to hide, show, or delete them. Please see the rest of the previous reply.
> Elaine C. Meng, Ph.D.
> UCSF Chimera(X) team
> Department of Pharmaceutical Chemistry
> University of California, San Francisco
>> On Nov 26, 2018, at 12:31 PM, Yu Guo <yg2 at kth.se> wrote:
>> Dear Elaine,
>> Thank you very much for help. Here I attach 6dho.pdb which has been converted from the original 6dho.cif by Openbabel. Since I am not very familar with the Chimera command, I hope you could make it easier with this .pdb file.
>> Best wishes
>> 发件人: Elaine Meng <meng at cgl.ucsf.edu>
>> 发送时间: 2018年11月26日 20:28
>> 收件人: Yu Guo
>> 抄送: chimera-users at cgl.ucsf.edu
>> 主题: Re: [Chimera-users] needing help for separating structures
>> Hi Yu Guo,
>> Well, it all depends on how these two states are described in the file. I took a look at the associated paper in Nature and they don’t really say exactly how they described the two states, but they do mention modeling them at reduced occupancy. So my best guess if one structure has more than one state, they are described in the file is with “alternate locations” for some atoms (i.e. multiple positions for a given atom) with reduced occupancy values. For me, it is harder to figure out with mmCIF file than PDB because I’m more familiar with looking at PDB files in a text editor.
>> Usually when there are alternate locations, they are A and B. So, you could select (or “delete” instead of “select” but then there is no going back other than by re-opening the original file) all atoms with alternate locations A with command:
>> select @.A
>> … and similarly for alternate location B. In my tests, it looks like A has the lower occupancy than B, and selecting alternate location A or B will each select 2188 atoms. You could also select by occupancy value; however, I get different numbers depending on the value I choose, presumably omitting some atoms with alternate locations or including some of the atoms that do NOT have alternate locations, so be careful using that method:
>> select @/occupancy<0.4
>> … I avoid using “=“ because rounding issues may prevent exact match
>> select @/occupancy<0.45
>> … or you can use a range, e.g.
>> select @/occupancy>0.5 and occupancy<0.75
>> Because they did not clearly state in the paper (or at least I didn’t see it), I could not be sure, but guessing that alternate location A is the minority state and alternate location B is the majority state, and atoms without alternate locations were the same in both states.
>> How I figured out that alternate location A appears to have lower occupancy than B is with these commands:
>> disp :ala
>> labelopt info occupancy
>> label :ala at .A
>> label :ala at .B
>> I hope this helps,
>> Elaine C. Meng, Ph.D.
>> UCSF Chimera(X) team
>> Department of Pharmaceutical Chemistry
>> University of California, San Francisco
>> P.S. ChimeraX is much faster reading mmCIF than Chimera. Also it automatically only uses the alternate location set with average higher occupancy (in this case B). However, if you want to show the altloc set with lower occupancy, there is no easy/convenient method for it yet, although it can be done with a setattr command.
>>> On Nov 24, 2018, at 11:28 AM, Yu Guo <yg2 at kth.se> wrote:
>>> Dear Sir/Madam,
>>> I am using Chimara to display large proteins. It is very nice. 6DHO(PDB structure, see attachment) is a very recent PSII structure consisting both S2 and S3(richer) states, which are highly overlapped in the raw data. I am urgently wondering how can I separate S3 out from the S2/S3 mixture by Chimera, especially the OEY cluster and all its ligands? Thank you very much!
>>> Best wishes
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