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[ccp4bb]: meta phosphate ion?!! (fwd)
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This is not a CCP4 related question. However, I hope some
could help me out.
We have refined a TIM-2PG (2-phosphoglycerate) structure at
1.1 ang. The asymmetric unit contains a dimer. The ligand
2PG properly defined in one of the subunits. However, the
electron density for 2PG in the other subunits was broken at
O-P bond. Hence, this was built as 2-oxoglycerate (2OG) and
PO3H. Breaking of 2PG into these species is not expected of
my question is concerned to PO3H. PO3H (HPO3 or PO3-) is a
metaphosphoric acid or metaphophate ion. The electron density
quite clearly confirm this. My problem is that it is known that
metaphosphates does not exist as single species due to their
stability properties. Therefore, we are having a situation where a
single metaphoshpate ion has been trapped in an enzyme's acitve
(a) is this possible for a metaphosphate ?
(b) can any one suggests references where such unexpected,
unstable species which known to be multimeric have been trapped in
the enzyme active site as a single molecular species ?
(c) There is also a remote chance that the density could also
be a Acetate ion (used during crystallization). What are the best
way and means of distinguishing between a metaphosphate ion and
an Acetate ion at 1.1 ang. ?
Thanking you all for ur forthcoming responses.
Molecular Biophysics Unit
Indian Institute of Science
Bangalore 560 012 India.