Dear Jim,
3.45 Angstrom is a perfectly normal resolution for a structure
mediated by 'wobbly' detergent / lipid contacts.
In this type of crystal the quality of the maps is the best indicator
of intrinsic protein order.
Send some density (in stereoview) to the journal as supplementary data.
Within a crystal, integral membrane domains can be less well resolved
than the intra / extracellular regions
- just as connecting loops can be disordered in high resolution
structures of any protein
- so on occasion a 2.9 A structure may be no better than a 5 A with
respect to the transmembrane helices.
Standard refinement statistics fail to convey this sort of information.
And, as I am sure you are aware, helices can be placed at 6 Angstroms.
Which seems to be your point.
Try another journal - you simply landed inexperienced reviewers.
As in any area of science it takes a while for dogma / prejudices to
dissipate.
Good Luck.
On 11/04/2008, at 8:04 PM, Jim Naismith wrote:
Dear All,
I have an interesting problem, we have a 3.45A structure of
a membrane protein. We have just been told that the structure is
"too low
resolution to be considered as the uncertainty is too high". We use
the
structure to identify helices which have moved.
Is there a blanket ban on low res structure operating at the moment?
The structure was refined extremely tightly, MolPROB 98th centile.
(I will
happily send the data and structure to anyone who wishes to
validate.) The
editors simply ignored everything but the res limit (I/sI in the
last shell
was 1.8 with a redundancy of 4)
Of course we will begin the usual journal shopping. However, does
anyone
know how to convince editors and non-xtallographers that 3.45A is
valid?
Best
Jim
James H. Naismith FRSE |Research mailto:[EMAIL PROTECTED]
and.ac.uk
Professor of Chemical Biology |Teaching mailto:[EMAIL PROTECTED]
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