How does one change the ideal bond length/sigma in Phenix?
JPK
From: Nigel Moriarty [mailto:[email protected]]
Sent: Tuesday, December 29, 2015 10:12 AM
To: Keller, Jacob
Cc: Boaz Shaanan; [email protected]
Subject: Re: [phenixbb] Modifications for Ca-binding site
Jacob
Boaz has some sage advice. I recommend not excluding the Ca-O coordination but changing the ideal to better reflect the distances in your files.
PS I'd also like the PDB files, directly, so as not to put noise on the list.
Cheers
Nigel
---
Nigel W. Moriarty
Building 33R0349, Physical Biosciences Division
Lawrence Berkeley National Laboratory
Berkeley, CA 94720-8235
Phone : 510-486-5709 Email : [email protected]
Fax : 510-486-5909 Web : CCI.LBL.gov
On Tue, Dec 29, 2015 at 5:49 AM, Keller, Jacob <[email protected]> wrote:
Well, I think it's more of a data-vs-geometry battle, with the geometry dragging in the side chains towards the calciums, and the data pulling them out. When I real-space refine them in Coot, some of the Ca-O distances are pretty different
from the "ideal" values. Maybe I could just exclude them from xyz refinement in Phenix after making sure they're correct in Coot? I'll give that a shot.
Kol tuv,
Jacob
-----Original Message-----
From: Boaz Shaanan [mailto:[email protected]]
Sent: Tuesday, December 29, 2015 7:52 AM
To: Keller, Jacob; [email protected]
Subject: RE: Modifications for Ca-binding site
Hi Jacob,
Sucking-up neighboring residues into the Calcium (or other heavier atoms) density is a known issue. Turning-off the Ca-O or other distance restraints around the Calcium is the last thing you want to do, in my experience. You'd better check those distance restraints
and verify that they're compatible with the distances in other (preferably high resolution, of course) structures with calcium binding sites similar to yours and then make sure they're given the appropriate weight during refinement. That's my view but Pavel
will give you more advices I'm sure.
Cheers,
Boaz
Boaz Shaanan, Ph.D.
Dept. of Life Sciences
Ben-Gurion University of the Negev
Beer-Sheva 84105
Israel
E-mail: [email protected]
Phone: 972-8-647-2220 Skype: boaz.shaanan
Fax: 972-8-647-2992 or 972-8-646-1710
________________________________________
From: [email protected] [[email protected]] on behalf of Keller, Jacob [[email protected]]
Sent: Tuesday, December 29, 2015 4:44 AM
To: [email protected]
Subject: [phenixbb] Modifications for Ca-binding site
I am getting a lot of problems with my calcium binding sites--there is clear density for the calciums and the protein side chains, but Phenix keeps sucking the side chains out of their density towards the calciums and also the calciums show some positive difference
density, perhaps due to too-high b-factors (or potentially partial occupancy by Na?). I think what might work best is to turn off the Ca-O bond length restraints somehow, but don't see where/how to do that. I tried releasing them from geometrical restraints,
but that made things worse, since things went haywire in the sidechains themselves.
Is it possible to make Phenix ignore the Ca-O bond distance restraints?
JPK
*******************************************
Jacob Pearson Keller, PhD
Looger Lab/HHMI Janelia Research Campus
19700 Helix Dr, Ashburn, VA 20147
email: [email protected]
*******************************************
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