RE: patch for cystein bond

From: Lennart Nilsson (Lennart.Nilsson_at_ki.se)
Date: Wed May 08 2019 - 15:10:34 CDT

Brian is right – please do read the documentation. The IC table does NOT create any energy terms (bonds, angles, etc).
For some reason you removed the all-important digits in front of the atom names…. They indicate which residue the atom belongs to, and without them all atoms are supposed to be in the same residue.

Best wishes,
Lennart Nilsson

From: owner-namd-l_at_ks.uiuc.edu [mailto:owner-namd-l_at_ks.uiuc.edu] On Behalf Of Brian Radak
Sent: den 8 maj 2019 20:15
To: namd-l <namd-l_at_ks.uiuc.edu>; Bernitzky, Cornelius Constantin Maria <cornelius.bernitzky_at_campus.tu-berlin.de>
Subject: Re: namd-l: patch for cystein bond

As it stands, this seems to be a question for the CHARMM RTF documentation.

How, and with what program, are you applying this patch?

On Wed, May 8, 2019 at 10:30 AM Bernitzky, Cornelius Constantin Maria <cornelius.bernitzky_at_campus.tu-berlin.de<mailto:cornelius.bernitzky_at_campus.tu-berlin.de>> wrote:

Dear developers,



I want to attach a cysteine to a gold-surface for NAMD-simulation, using a patch within the topology-file.



The patch is as the following:



    PRES AUST -0.36 ! patch for CYS on gold surface
                                       ! use in a patch statement
                                       ! follow with AUTOgenerate ANGLes DIHEdrals command?
    GROUP
    ATOM CB CT2 -0.10 ! | .
    ATOM SG SM -0.08 ! HN-N .
    GROUP ! | HB1 .
    ATOM A12 AU -0.08 ! | | A11
    ATOM A13 AU -0.10 ! HA-CA--CB--SG--A12
                                            ! | | A13
                                            ! | HB2 .
                                            ! O=C .
    DELETE ATOM HG1 ! | .
    BOND SG A12
    DONOR SG A12
    IC CA CB SG A12 1.5584 109.0000 176.9600 114.20 2.45
    IC CB SG A12 A13 1.86 114.20 180.0000 90.0000 2.884



I derived this from the working DISU-patch, but noticed that the patch do not use the existing gold surface.

It creates two new Au atoms, where "A12" is bound to the Sulfur under usage of the given internal coordinates.



As it is stated in the NAMD-tutorial (https://www.ks.uiuc.edu/Training/Tutorials/namd/namd-tutorial-unix-html/node24.html)

the ATOM command within patches can refer to adding a new atom (as it happens here) or to the modifying of existing atoms (what happens in the DISU-patch and what is desired for my case too).



Do you can think of an idea, how to make NAMD use the existing gold-surface instead of adding new Au?

The gold is defined in a .pdb like this:

ATOM 167 A11 AUR A 2 -58.558 -59.167 -52.227 1.00 0.00 B AU





Best wishes,

C. Bernitzky





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