[chimerax-users] How to draw the surface of cavity

[Elaine Meng]

Hello Lingyi,
ChimeraX and Chimera do not have easy ways to show cavity surfaces, unfortunately.  But there are a few related possibilities:

(1) show molecular surface, but not the whole thing, only for the atoms that surround the cavity.  If the cavity is completely closed by surrounding protein, then it looks pretty nice.  However, in most cases there are openings so you may get uneven edges from surface triangles.  ChimeraX does not have a way to cleanly draw the boundary between the pocket surface and the surrounding surface.

Example with ligand in pocket:
open 2gbp
surface protein & ligand :<4 visiblePatches 1

If you don't have a ligand in the pocket to define a distance zone (4 Angstroms above) you would instead need to list all the residues/atoms of the protein that form the pocket, which can be difficult.

(2) use a separate web server to identify pockets or calculate a blob that fills a cavity, and then open the results.  

(2a) show CASTp-calculated pockets -- this also works by showing partial molecular surfaces in Chimera.  Chimera has a nice tool for looking through the pockets
<http://plato.cgl.ucsf.edu/chimera/docs/UsersGuide/castp.html>

Chimera example:  
open castp:2gbp

ChimeraX does not have this feature, but if you did it in Chimera and displayed the pocket(s) that you want, then you could try Chimera export to ChimeraX, Chimera menu: File... Export Scene, choose the ChimeraX option.
<https://www.rbvi.ucsf.edu/chimera/docs/UsersGuide/export.html>

(2b) MOLEonline server does this but it also makes files for Chimera, not ChimeraX (again, maybe you can use the export from Chimera to ChimeraX).
<https://mole.upol.cz/>

(2c) 3Vee server makes a map that fills pockets, which I believe you could open in either Chimera or ChimeraX and then display as isosurface.
<http://3vee.molmovdb.org/>

There are probably other servers that I haven't found.
I hope this helps,
Elaine
-----
Elaine C. Meng, Ph.D.                       
UCSF Chimera(X) team
Department of Pharmaceutical Chemistry
University of California, San Francisco

> On Mar 29, 2022, at 10:53 PM, 令怡 via ChimeraX-users <chimerax-users at cgl.ucsf.edu> wrote:
> 
> Dear ChimeraX Staff,
> Hello! I would like to know if there's a way to display the cavity like this? I've been studying for a long time without a clue.
> Thank you for your attention!
> Best Regards,
> Lingyi