Li+ has only 2 electrons, and the B-factor is telling you that the refinement wants more there.
So no, not justified. Check coordination and distances, maybe water or bigger ion.
Cheers, BR
-----Original Message-----
From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of Mohamed Noor
Sent: Monday, March 14, 2016 3:34 PM
To: [log in to unmask]
Subject: [ccp4bb] Lithium ion placement
Dear crystallographers
I have a crystal diffracting to 2.3 A, where I can place a Li+ in the vicinity of O atom of a Glu (2.5 A) and NZ atom of a Lys (2.8 A). The B factor is 6.5 A^2 whereas the NZ of Lys is about 60 A^2 and the O of Glu is 50 A^2. Does it mean the Li+ ion is justifiably placed?
The crystallization mix contained about 50 mM LiCl in 2.5 Na/K phosphate buffer.
Thanks.
Mohamed
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