Thanks, Randy.
Molrep must be failing due to some other flaw in my procedure, as it
clearly uses the P21 cell, as evidenced by the output CRYST1 and ViewHKL in
qtRView of ccp4i.
Can you suggest any alternative procedures that would expand that
C-centered data set into the primitive setting?
W.
---------- Forwarded message ----------
From: Randy J. Read <rj...@cam.ac.uk>
Date: Wed, Oct 2, 2013 at 1:07 PM
Subject: Re: [ccp4bb] expanding reflections from C2221 to P21
To: wtempel <wtem...@gmail.com>
Cc: "CCP4BB@JISCMAIL.AC.UK" <CCP4BB@jiscmail.ac.uk>
I suspect the problem is that sftools hasn't been modernised to alter all
the cell dimension records used in current MTZ files. I can't remember
right now but maybe the DCELL command in cad might fix it.
Randy Read
----
Randy J. Read
On 2 Oct 2013, at 17:13, wtempel <wtem...@gmail.com> wrote:
Hello,
I would like to expand a reflection data set in mtz format from C2221 to
P21. The purpose is to obtain consistent R-free flags based on a structure
already refined in C2221 for a related data set that I suspect is
pseudo-C2221 but "real" P21.
Primitive cell dimensions are: 37.6 126.1 40.61 89.99 117.6 90.01,
C-centered: 37.6 71.99 126.1 90 89.99 90.01
pointless provides the following matrix:
<pointless>
Reindex operator from input cell to lattice cell: [h,h+2l,-k]
h' = ( h k l ) ( 1 1 0 )
( 0 0 -1 )
( 0 2 0 )
</pointless>
In sftools, I loaded the C2221 data set and did
sftools$ reindex matrix 1 0 0 0 0 -1 -.5 .5 0
with the transposed (to account for the presumably inverted order of
factors in the program?) inverse matrix of the one listed above with the
aim of restoring the primitive asymmetric unit.
I was encouraged seeing sftools report new cell dimensions matching the
expected primitive cell.
Then I did
sftools$ expand 4
I expected now to have a "workable" P21 version of my C2221 data set, but
molecular replacement (MOLREP) with my C2221 model failed to place even a
single copy of the model.
Thus, I must have misused sftools by issuing commands that were either
wrong or in the wrong order or my application of linear algebra was
mistaken.
Any ideas out there?
Thanking you in advance,
Wolfram Tempel
