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PDBsum entry 3e3d
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References listed in PDB file
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Key reference
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Title
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A magic triangle for experimental phasing of macromolecules.
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Authors
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T.Beck,
A.Krasauskas,
T.Gruene,
G.M.Sheldrick.
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Ref.
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Acta Crystallogr D Biol Crystallogr, 2008,
64,
1179-1182.
[DOI no: ]
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PubMed id
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Abstract
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Obtaining phase information for the solution of macromolecular structures is
still one of the bottlenecks in X-ray crystallography.
5-Amino-2,4,6-triiodoisophthalic acid (I3C), in which three covalently bound
iodines form an equilateral triangle, was incorporated into proteins in order to
obtain phases by single-wavelength anomalous dispersion (SAD). An improved
binding capability compared with simple heavy-metal ions, ready availability,
improved recognition of potential heavy-atom sites and low toxicity make I3C
particularly suitable for experimental phasing.
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Figure 1.
Figure 1 I3C and its interaction with proteins. (a)
5-Amino-2,4,6-triidoisophthalic acid (I3C) with three I atoms
for anomalous scattering and three functional groups for
hydrogen bonding. (b) One molecule of I3C in lysozyme; anomalous
electron density at 4  (orange),
distances in Å. The equilateral triangle formed by the I
atoms is clearly visible. (c) Hydrogen bonding of the amino
group of I3C with the main-chain carbonyl O atom of Asp21 in
thaumatin (other interactions are not shown). (d) Interaction of
I3C with three lysozyme molecules. Hydrogen bonds to Arg73
(left), Lys33 (top right) and Ser24 (bottom right) are shown by
dashed lines.
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The above figure is
reprinted
by permission from the IUCr:
Acta Crystallogr D Biol Crystallogr
(2008,
64,
1179-1182)
copyright 2008.
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