NH4+ vs H2O
dunten at daisy.bmc.uu.se
Wed Apr 20 08:38:14 EST 1994
Thanks for all the replies.
I was directed to a reference:
Axelsen et al. Protein Science Vol. 3 (1994) pp 188-197
fascinating work in which a ligand is discovered
in the active site gorge of AChE after checking a
Fo - Fc map with data from 20 - 2.8 A. The ligand
+(CH3)3 N (CH2)10 N (CH3)3+ was originally modelled as
5 water molecules based on a Fo - Fc map with data
from 8 - 2.8 A. In addition, evidence is presented
that 2 other waters are probably NH4+ ions.
Gerard Kleywegt grepped the pdb for me, finding NH4
in 1pal and 2act, ND4 in 2mb5, and AMMONIUM ION in 3chy.
Raul Cachau pointed out that it's much worse than NH4+ vs. H2O.
There are also Na+, Mg++, F-, H3O+, etc, etc to
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