Thanks Pavel! I will wait and see what Ralf says regarding defining the symmetry operator. If I am using the GUI for phenix.refine should I create a new file with the bond definition you mention and include it as one of the starting files or should I edit the Refine_*.eff file that gets created and insert it somewhere there? ___________________________________________________________ Joseph P. Noel, Ph.D. Investigator, Howard Hughes Medical Institute Professor, The Jack H. Skirball Center for Chemical Biology and Proteomics The Salk Institute for Biological Studies 10010 North Torrey Pines Road La Jolla, CA 92037 USA Phone: (858) 453-4100 extension 1442 Cell: (858) 349-4700 Fax: (858) 597-0855 E-mail: [email protected] Web Site (Salk): http://www.salk.edu/faculty/faculty_details.php?id=37 Web Site (HHMI): http://hhmi.org/research/investigators/noel.html ___________________________________________________________ On Aug 4, 2010, at 10:22 AM, [email protected] wrote:

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Today's Topics:

1. Re: DTT mediated disulfide crosslink across a crystallographic two-fold! (Joseph Noel) 2. Re: high average b-factor vs. Wilson B (Gino Cingolani) 3. Re: high average b-factor vs. Wilson B (Frank von Delft) 4. Re: DTT mediated disulfide crosslink across a crystallographic two-fold! (Pavel Afonine) 5. Re: high average b-factor vs. Wilson B (Pavel Afonine) 6. r-work and r-free for specific resolution range(s) (Kay Diederichs)

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Message: 1 Date: Wed, 4 Aug 2010 04:53:25 -0700 From: Joseph Noel To: [email protected] Subject: Re: [phenixbb] DTT mediated disulfide crosslink across a crystallographic two-fold! Message-ID: <[email protected]> Content-Type: text/plain; charset="us-ascii"

Hi Ralf and Pavel,

Unfortunately, Phenix didn't recognize a disulfide bond should exist between the sulfur atoms of DTT and the side chain sulfur atom of the cysteine residue in question. I position everything well in the Fo-Fc and 2Fo-Fc maps and ensured the two sulfurs were approximately 2.1 A apart. However, after refinement the DTT molecule moved so the two sulfurs in question where nearly 3 A away. Maybe this is because it is a mixed disulfide between a DTT molecule and a side-chain Cys rather then what most programs expect which is a disulfide between two Cys residues. Is it possible I need to define the complete chemical entity as a hetatm (the disulfide linked Cys residue? Is there a way to specify that a covalent bond should exist between the SG atom of the Cys in question and the S atoms of DTT with DTT lying across the crystallographic two-fold given its internal 2-fold symmetry?

Joe ___________________________________________________________ Joseph P. Noel, Ph.D. Investigator, Howard Hughes Medical Institute Professor, The Jack H. Skirball Center for Chemical Biology and Proteomics The Salk Institute for Biological Studies 10010 North Torrey Pines Road La Jolla, CA 92037 USA

Phone: (858) 453-4100 extension 1442 Cell: (858) 349-4700 Fax: (858) 597-0855 E-mail: [email protected]

Web Site (Salk): http://www.salk.edu/faculty/faculty_details.php?id=37 Web Site (HHMI): http://hhmi.org/research/investigators/noel.html ___________________________________________________________