On Fri, 2011-06-24 at 09:50 +0200, mullapudi edukondalu wrote:
> Dear Members,
>
> I have my first data set on one of my protein crystals, that diffract
> to 2.7 A, and the space group is I222. According to Mathews
> coefficient, there should be 4 molecules in the asymmetric unit. But,
> when I run molecular replacement programme it found only 3, and the
> crystal packing is not that good. I have 100% similar model. And Ref
> mac gave me an Rfree of 46%. Could any one of you please suggest me
> how to go further with this problem? Looking forward to hear from you.
>
> Best Regards
>
> Edukondalu Mullapudi
>
Phil is absolutely right - you have to check alternative space group.
Actually, if you used Phaser with default settings it would try
alternatives for you automatically.
There are other possibilities, of course. An incomplete list would
include (in random order) domain movements, twinning, incorrect
spacegroup, disordered copies, etc. I have seen once a dataset where
three copies in the asu were all so different that MR with either of
them could only find a single copy.
Cheers,
Ed.
--
"Hurry up before we all come back to our senses!"
Julian, King of Lemurs
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