Yes - I have seen something similar at a lower resolution, but very
ugly! I tried to model it as a solvent molecule - possible but not too
convincing..
Cl should give an anomalous signal - try a DANO map and see what it shows..
Eleanor
On 11/17/2011 11:09 AM, Dean Derbyshire wrote:
Hi all,
Has anyone observed 'odd' arginine residues, missing the NH1 atom; and possibly
related.. very close Chlorine-arginine (NH1 again) distances.
I have a 1.3Å structure and am having trouble getting my head around some very
odd density features.
I have 2 molecules in the assym. with the equivalent arg residues showing the
same odd feature.
Seems to be a chlorine binding site - typical mix of hydrophobic and proton
rich side chains - but, the NH1 of the particular arginine residue concerned
(as I say in both NCS copies) seems to have only 50% occupancy and the chlorine
appears to have a 2nd distinct position closer to the arginine, such that if
the NH1 atom were present it would be only 2Å away!
?
Cheers in advance
Dean
