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PDBsum entry 1jnn
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Immune system
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PDB id
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1jnn
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Highly specific anti-Estradiol antibodies: structural characterisation and binding diversity.
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Authors
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C.Monnet,
F.Bettsworth,
E.A.Stura,
M.H.Le du,
R.Ménez,
L.Derrien,
S.Zinn-Justin,
B.Gilquin,
G.Sibaï,
N.Battail-Poirot,
M.Jolivet,
A.Ménez,
M.Arnaud,
F.Ducancel,
J.B.Charbonnier.
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Ref.
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J Mol Biol, 2002,
315,
699-712.
[DOI no: ]
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PubMed id
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Abstract
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Subtle modulation of antibody-binding properties by protein engineering often
lies with an accurate structural and energetic description of how an antigen is
recognised. Thus, with the intent to increase the affinity and add a bias in
favour of natural estradiol compared with its chemically modified immunogen, we
have determined the crystal structure of two anti-estradiol monoclonal
antibodies, 10G6D6 and 17E12E5. Although generated against the same estradiol
derivative, these antibodies share little sequence identity, which is reflected
in dissimilar binding pockets and in different positioning of the steroid. In
both antibodies the characteristic 17-hydroxyl group is buried deeply at the
bottom of hydrophobic pockets and stabilised by hydrogen bonds. Apart from this
similarity, the steroid is oriented differently in the respective binding
pockets. The high specificity of both antibodies has been mapped out, and even
closely related steroids show low cross-reactivity. The structural studies of
the complex formed between 10G6D6 and 6-CMO-estradiol have identified contacts
between the 6-CMO coupling linker and an arginine residue from the heavy chain
CDR2 segment. This segment is now being targeted by random mutagenesis to select
mutants with a preference for natural estradiol compared to the branched hapten.
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Figure 1.
Figure 1. A representation of the steroid hormones used in
this study. Ligands present in the crystal structure of
antibodies 17E12 and 10G6 are (1) 17b-estradiol and (2)
17b-estradiol-6CMO. Numbering of atoms is shown on the structure
of the 17b-estradiol. Cross-reactivity experiments were made
with compounds 1 to 15. The antibodies were generated against
17b-estradiol-6EMC (16).
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Figure 3.
Figure 3. Antibody-estradiol interactions (a) for Fab' 10G6
and (b) for Fab' 17E12. The view is in ball-and-stick of the
main residues from the Fab' in contact with the estradiol and in
broken lines of the hydrogen bonds with the O17 hydroxyl group.
The estradiol, the V[H] and the V[L] regions are coloured in
green, blue and yellow, respectively. The C6 atom of the
estradiol, where the linker is attached, is represented in dark
green. Figure 3, Figure 4 and Figure 5 were made with MOLMOL.[14]
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2002,
315,
699-712)
copyright 2002.
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