In my experience, even when rather magically Phaser works with 20-25% identity, with 2.0 data you cannot always proceed to change and refine your structure.
I would focus on the Se synchrtron data, or collect a very redundant set at the home source, which should allow you to find the Se and do some good phasing.
Tassos
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From: CCP4 bulletin board [[log in to unmask]] On Behalf Of Narayanan Ramasubbu [[log in to unmask]]
Sent: Thursday, December 10, 2009 4:40 PM
To: [log in to unmask]
Subject: [ccp4bb] Difficult MR structures
Deal All:
I have a 2.0 A data for a SeMet protein (native crystal not available
yet!) that has 6 Se sites.
The cell comes out to be 65 67 101 and the angles are all very close to
90. The data set was collected in house with Cu 1.5418 A
We integrated and scale in orthorhombic and the statistics are reasonable.
There are 4 homologous structures and all of them have a sequence
identity of 15-16 %.
I have tried Phaser, AMoRe, EPMR with varying templates
with polyala, polyser and varying the resolutions.
I have also done a modeller and found best match with one of the four
structures. I have used this derived model as well for input.
I would like to know whether there other options (I am working on
getting a good synchrotron data set at the peak wavelength for Se).
Thanks
Subbu
PS: I am also trying P1 just in case.
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