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PDBsum entry 1nht
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References listed in PDB file
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Key reference
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Title
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Entrapment of 6-Thiophosphoryl-Imp in the active site of crystalline adenylosuccinate synthetase from escherichia coli.
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Authors
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B.W.Poland,
C.Bruns,
H.J.Fromm,
R.B.Honzatko.
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Ref.
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J Biol Chem, 1997,
272,
15200-15205.
[DOI no: ]
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PubMed id
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Note In the PDB file this reference is
annotated as "TO BE PUBLISHED".
The citation details given above were identified by an automated
search of PubMed on title and author
names, giving a
perfect match.
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Abstract
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Crystal structures of adenylosuccinate synthetase from Escherichia coli
complexed with Mg2+, 6-thiophosphoryl-IMP, GDP, and hadacidin at 298 and 100 K
have been refined to R-factors of 0.171 and 0.206 against data to 2.8 and 2.5 A
resolution, respectively. Interactions of GDP, Mg2+ and hadacidin are similar to
those observed for the same ligands in the complex of IMP, GDP, NO3-, Mg2+ and
hadacidin (Poland, B. W., Fromm, H. J. & Honzatko, R. B. (1996). J. Mol.
Biol. 264, 1013-1027). Although crystals were grown from solutions containing
6-mercapto-IMP and GTP, the electron density at the active site is consistent
with 6-thiophosphoryl-IMP and GDP. Asp-13 and Gln-224 probably work in concert
to stabilize the 6-thioanion of 6-mercapto-IMP, which in turn is the nucleophile
in the displacement of GDP from the gamma-phosphate of GTP. Once formed,
6-thiophosphoryl-IMP is stable in the active site of the enzyme under the
conditions of the structural investigation. The direct observation of
6-thiophosphoryl-IMP in the active site is consistent with the putative
generation of 6-phosphoryl-IMP along the reaction pathway of the synthetase.
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Figure 2.
Fig. 2. Stereo view of bound ligands in relation to a trace
of  -carbons of
adenylosuccinate synthetase.
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Figure 6.
Fig. 6. Proposed mechanism for the phosphotransfer reaction
governed by the synthetase, involving 6-mercapto-IMP as a
substrate. L-Aspartate is not shown here but is putatively
coordinated to Mg2+ as shown in Fig. 7.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(1997,
272,
15200-15205)
copyright 1997.
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Secondary reference #1
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Title
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Refined crystal structures of unligated adenylosuccinate synthetase from escherichia coli.
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Authors
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M.M.Silva,
B.W.Poland,
C.R.Hoffman,
H.J.Fromm,
R.B.Honzatko.
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Ref.
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J Mol Biol, 1995,
254,
431-446.
[DOI no: ]
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PubMed id
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Figure 1.
Figure 1. Amino acid sequence used in the refinement
of unligated crystal structures of the synthetase.
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Figure 8.
Figure 8. Identification of the active site of the synthetase (top) by the location of IMP and GDP in a preliminary
crystal structure, (middle) by directed mutation, and (bottom) by the mapping of conserved residues of synthetases from
bacteria, yeast and mammals. Drawing by MOLSCRIPT (Kraulis, 1991).
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The above figures are
reproduced from the cited reference
with permission from Elsevier
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Secondary reference #2
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Title
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Crystal structure of adenylosuccinate synthetase from escherichia coli. Evidence for convergent evolution of gtp-Binding domains.
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Authors
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B.W.Poland,
M.M.Silva,
M.A.Serra,
Y.Cho,
K.H.Kim,
E.M.Harris,
R.B.Honzatko.
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Ref.
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J Biol Chem, 1993,
268,
25334-25342.
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PubMed id
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