Hi -
Let me just add that P312 is a very uncommon space group for protein
crystals, much less common than P321. (This doesn't mean you don't have
it - it's just unlikely.) If you look at PDB statistics:
P 3 1 2 : 12 structures
P3(1) 1 2: 61 structures
P3(2) 1 2: 85 structures
P 3 2 1 : 278 structures
P3(1) 2 1: 2354 structures
P3(2) 2 1: 2533 structures
This also suggests, by the way, that you have a screw axis that you
haven't accounted for yet. It won't affect your data scaling, but it
sure will affect your molecular replacement job!
Hope that helps,
Matt
On 4/5/12 12:31 PM, Deepthi wrote:
Hello
I arrived at the p312 space group by running a self rotation function
using MOLREP. The maps show the space group as p312. I was scaling the
data individually for each wavelength. None of the three wavelengths
are scaling are scaling in p312 space group.
On Thu, Apr 5, 2012 at 2:17 AM, Clemens Vonrhein
<vonrh...@globalphasing.com <mailto:vonrh...@globalphasing.com>> wrote:
Hi,
On Wed, Apr 04, 2012 at 02:07:58PM -0700, Deepthi wrote:
> Hello everyone
> I have a problem scaling the MAD data which was collected a week
ago.The
> data was collected at 1.5A resolution using three wavelengths
for Zn-MAD
> experiments. Scaling the data for MAD experiments, the number of
rejections
> and chi2 values were very high even after adjusting the
error-scale factor
> and error model. The space group i used was p312 which i obtained by
> running a self-rotation function in MOLREP. When i scale my data
using p312
> spacegroup the chi2 and rejections were huge. But he data was
scaling well
> in p321 spacegroup. can anyone explain whats going on?
When you say 'Scaling the data for MAD experiments': do you mean
scaling the various scans for your 3-wvl MAD data in a single scaling
job? Unless you already took care of this during data integration,
remember that your separate scans could have been indexed differently
and therefore don't match up. See eg.
http://www.ccp4.ac.uk/html/reindexing.html
for some lookup-tables in P312 and P321. You can use the CCP4 program
'reindex' on MTZ files if needed.
But I guess most modern data-processing and scaling programs will take
care of that automatically anyway?
Cheers
Clemens
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Deepthi
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Matthew Franklin, Ph. D.
Senior Research Scientist
New York Structural Biology Center
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