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PDBsum entry 2wbc
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Serine protease inhibitor
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PDB id
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2wbc
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References listed in PDB file
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Key reference
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Title
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Refined crystal structure (2.3 a) of a double-Headed winged bean alpha-Chymotrypsin inhibitor and location of its second reactive site.
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Authors
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J.K.Dattagupta,
A.Podder,
C.Chakrabarti,
U.Sen,
D.Mukhopadhyay,
S.K.Dutta,
M.Singh.
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Ref.
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Proteins, 1999,
35,
321-331.
[DOI no: ]
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PubMed id
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Abstract
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The crystal structure of a double-headed alpha-chymotrypsin inhibitor, WCI, from
winged bean seeds has now been refined at 2.3 A resolution to an R-factor of
18.7% for 9,897 reflections. The crystals belong to the hexagonal space group
P6(1)22 with cell parameters a = b = 61.8 A and c = 212.8 A. The final model has
a good stereochemistry and a root mean square deviation of 0.011 A and 1.14
degrees from ideality for bond length and bond angles, respectively. A total of
109 ordered solvent molecules were localized in the structure. This improved
structure at 2.3 A led to an understanding of the mechanism of inhibition of the
protein against alpha-chymotrypsin. An analysis of this higher resolution
structure also helped us to predict the location of the second reactive site of
the protein, about which no previous biochemical information was available. The
inhibitor structure is spherical and has twelve anti-parallel beta-strands with
connecting loops arranged in a characteristic beta-trefoil fold common to other
homologous serine protease inhibitors in the Kunitz (STI) family as well as to
some non homologous functionally unrelated proteins. A wide variation in the
surface loop regions is seen in the latter ones.
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Figure 5.
Figure 5. The first reactive site of WCI (green) is docked at
the enzyme (magenta) active site (van der Waals surface is
shown). shows His57 at the center having a hydrophobic
environment (partially shown for clarity in viewing).
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Figure 8.
Figure 8. The canonical conformation of the second reactive
site loop. The side-chain of Glu39 intrudes inside the loop and
stabilizes it through hydrogen bonding.
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The above figures are
reprinted
by permission from John Wiley & Sons, Inc.:
Proteins
(1999,
35,
321-331)
copyright 1999.
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Secondary reference #1
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Title
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Crystallization and preliminary X-Ray studies of psophocarpin b1, A chymotrypsin inhibitor from winged bean seeds.
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Authors
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J.K.Dattagupta,
C.Chakrabarti,
A.Podder,
S.K.Dutta,
M.Singh.
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Ref.
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J Mol Biol, 1990,
216,
229-231.
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PubMed id
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