Hi all Chimera users,

 

I would like to know how to calculate the values of Coulombic ESP on the interface between two proteins:

 

At the moment I have done the following:

*UCSF Chimera version 1.14

Commands:

    open 1avx

display

~longbond 

split

delete solvent 

surf #0.1

 

Tools>Surface/Binding analysis>Coulombic surface coloring

>Check the box compute grid

>Apply

>Surface color>Options

                     >Check the box Report value at mouse position

                     >Click color:

 

All the electrostatic potential values appear by Coulombic Kcal/(Mol.e) at the mouse position:

 

imagen.png

Commands:

~surface #0.1

measure buriedArea  #0.1  #0.2

select #0.1@/buriedSASArea> 1

surf sel

 

Volume viewer>Tools>Values at atom position>Click Histogram

 

imagen.png


Is there a way to save all the ESP Coulombic values in the selected interface surface in a file?

Is it possible to calculate the polar and non-polar surface area in the interface?

Regards,

Fer.






El lun., 16 de sep. de 2019 a la(s) 17:39, Tom Goddard (goddard@sonic.net) escribió:
Hi Fernando,

  I don't understand what you need vertex coordinates for.  But you could put a print statement into the Chimera Python code that does surface coloring to output vertex coordinates and potential values.  This would be in file

 chimera/share/SurfaceColor/__init__.py

or on Mac in 

Chimera.app/Contents/Resources/share/SurfaceColor/__init__.py

in the volume_values() routine change

    def volume_values(self, surface_piece):

        p = surface_piece
        xf = p.model.openState.xform
        v = p.geometry[0]
        n = p.normals
        return self.offset_values(v, n, xf)

to

    def volume_values(self, surface_piece):

        p = surface_piece
        xf = p.model.openState.xform
        v = p.geometry[0]
        n = p.normals
        values, outside = self.offset_values(v, n, xf)
print '\n'.join('%.5g %.5g %.5g %.5g'  % (x, y, z, val) for (x,y,z), val in zip(v, values))
        return values, outside

Use the Surface Color tool and the vertices and values will be printed to the reply log.

  Tom


On Sep 16, 2019, at 1:20 PM, Fernando Villa <fer.vdl1928@gmail.com> wrote:

Dear Tom and Chimera users,

In ChimeraX or Chimera, is it possible to calculate the number of vertices and their respective total charges?

I calculated the electrostatic potential surface (Coulombic) with another program, it gave me the following results (attached in this email) and I calculated the area in red and blue, above and below a threshold = 0.

Unfortunately, these results do not help me, because I need to obtain an electrostatics calculations from Adaptive Poisson-Boltzmann Solver (Calculations that I have already made for study proteins with PDB2PQR and APBS, in interface with Chimera: .pqr and .dx files and emulated in Chimera X)

e.g.
<image.png>

Now my question is:
Can I obtain these results of vertices and charges in a file from Chimera or Chimera X (possibly .cvs, .txt, etc.), so that I can make the corresponding calculations?

I would greatly appreciate your help

best regards,

Fer



El lun., 16 de sep. de 2019 a la(s) 13:03, Tom Goddard (goddard@sonic.net) escribió:
Hi Fernando,

  Instead of thinking about the coloring, it would be clearer to ask how much surface area has electrostatic potential value >= 5.  Chimera does not have any code to compute that, although it is something we could add to ChimeraX.

Tom


On Sep 11, 2019, at 7:27 PM, Fernando Villa <fer.vdl1928@gmail.com> wrote:

Dear all Chimera users

In UCSF ChimeraX version 0.91 (2019-08-30)
I opened a .pqr file (generated with pdb2pqr in Chimera 1.14)  and then I opened a .dx file (generated with APBS in Chimera 1.14)

Then I input the commands:

>surface
>color electrostatic #1 map #2 palette -10,red:0,white:10,blue

<image.png>
Is it possible to calculate the red and blue area in Å2 of the molecule?

Best regards,

Fernando


ATTE
Fernando Villa Díaz


_______________________________________________
Chimera-users mailing list: Chimera-users@cgl.ucsf.edu
Manage subscription: http://plato.cgl.ucsf.edu/mailman/listinfo/chimera-users

<Test_MEP_Protein.xlsx>_______________________________________________
Chimera-users mailing list: Chimera-users@cgl.ucsf.edu
Manage subscription: http://plato.cgl.ucsf.edu/mailman/listinfo/chimera-users