Does the SAXS model contain more than one subunit? If so, I would be tempted to
go back to the model and try each one separately. This may not apply, but if
there are monomers in the SAXS model that are related by space group symmetry
in the crystal, I think the MR would never work. Good luck with it! Bests, Jon.
Cooper
Sent from Yahoo Mail on Android
On Sat, 1 Jun 2019 at 9:45, Jrh Gmail<jrhelliw...@gmail.com> wrote: Dear
KevinYou could try reindexing into P1, then run Phaser and with its solution as
input to Zanuda determine the space group. Best wishes,John
Emeritus Professor of Chemistry John R Helliwell DSc_Physics
On 31 May 2019, at 21:09, Kevin Jude <kj...@stanford.edu> wrote:
Hello community, I wonder if I could solicit advice about a problematic
dataset. I plan to solve the structure by molecular replacement and expect that
the protein is relatively compact, ie not elongated. SAXS data supports this
expectation.
The crystals diffract to 2.6 Å resolution and appear to be in P 21 21 2 with a
= 49, b = 67, c = 94, which should fit <=2 molecules in the ASU with 40%
solvent. The native Patterson shows a large peak (12 sigma) suggesting a tNCS
vector of {0.5, 0.5, 0}.
If you're sharper than me, you may have already spotted the problem - c is the
long axis of the unit cell, but tNCS constrains the proteins to a plane
parallel to the a,b plane. Indeed, molecular replacement attempts using Phaser
will not give a solution in any orthorhombic space group unless I turn off
packing, and then I get large overlaps in the a,b plane and huge gaps along c.
Since I believe that my model is good (or at least the correct shape, based on
SAXS), I wonder if I'm misinterpreting my crystallographic data. Any insights
into how to approach this problem would be much appreciated.
--
Kevin Jude, PhDStructural Biology Research Specialist, Garcia LabHoward Hughes
Medical InstituteStanford University School of MedicineBeckman B177, 279 Campus
Drive, Stanford CA 94305Phone: (650) 723-6431
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