[phenixbb] refinement of partly occupied water molecules?

[Nicholas Keep]

Could well be a cation-pi interaction.  Have been reading up on Arg/Trp 
interactions and sitting above the ring is a classic place for a cation. 
See
The Cation
-π Interaction  DENNIS A. DOUGHERTY ACCOUNTS OF CHEMICAL 
RESEARCH ’ 885–893 ’ 2013 ’ Vol. 46, No. 4
for up to date or I found Ma, J. C., and Dougherty, D. A. (1997) The 
cation-pi interaction. Chemical Reviews 97, 1303-132
better from a structural biology point of view.

I would go with a metal ion or ammonium but as to which one I have no idea.

Best wishes
Nick

-- 
Prof Nicholas H. Keep
Executive Dean of School of Science
Professor of Biomolecular Science
Crystallography, Institute for Structural and Molecular Biology,
Department of Biological Sciences
Birkbeck,  University of London,
Malet Street,
Bloomsbury
LONDON
WC1E 7HX

email     n.keep at mail.cryst.bbk.ac.uk
Telephone 020-7631-6852  (Room G54a Office)
           020-7631-6800  (Department Office)
Fax       020-7631-6803
If you want to access me in person you have to come to the 
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and ring me or the department office from the internal phone by the door