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PDBsum entry 1hss
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Cereal inhibitor
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PDB id
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1hss
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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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Tertiary and quaternary structures of 0.19 alpha-Amylase inhibitor from wheat kernel determined by X-Ray analysis at 2.06 a resolution.
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Authors
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Y.Oda,
T.Matsunaga,
K.Fukuyama,
T.Miyazaki,
T.Morimoto.
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Ref.
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Biochemistry, 1997,
36,
13503-13511.
[DOI no: ]
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PubMed id
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Abstract
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The crystal structure of 0.19 alpha-amylase inhibitor (0.19 AI) from wheat
kernel was determined by the multiple-isomorphous replacement method coupled
with density modification and noncrystallographic symmetry averaging and then
refined by simulated annealing using diffraction data to 2.06 A resolution (R =
18.7%, free R = 22.3%). The asymmetric unit has four molecules of 0.19 AI, each
comprised of 124 amino acid residues. Electron density for residues 1-4 and
69-77 is absent in all subunits, probably because of the intrinsic flexibility
of these segments. Each subunit has four major alpha-helices and one one-turn
helix which are arranged in the up-and-down manner, maintaining the favorable
packing modes of the alpha-helices. 0.19 AI, however, has two short antiparallel
beta-strands. All 10 cysteine residues in 0.19 AI form disulfide bonds (C6-C52,
C20-C41, C28-C83, C42-C99, and C54-C115), consistent with the assignments made
biochemically for 0.28 AI from wheat kernel and by NMR analysis of the
bifunctional alpha-amylase/trypsin inhibitor from ragi seeds (RBI). The
disulfide bond patterns in these AIs are similar to those in the hydrophobic
protein from soybean (HPS), which lack only the bond corresponding to C28-C83 in
0.19 AI. Extensive interactions occurred between particular pairs of 0.19 AI
subunits, mainly involving hydrophobic residues. Comparisons of the structures
of 0.19 AI, RBI, and HPS showed that the arrangements of the major alpha-helices
are similar but the conformations of the remaining residues differ markedly. The
present X-ray analysis for 0.19 AI and the NMR analysis for RBI suggest that all
the AIs in this family have a common fold. The alpha-amylase binding site is
discussed on the basis of the tertiary and quaternary structures of 0.19 AI
together with biochemical and spectroscopic data for AIs.
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Secondary reference #1
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Title
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Crystallization and preliminary X-Ray diffraction studies of the alpha-Amylase inhibitor coded 0.19 from wheat kernel.
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Authors
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T.Miyazaki,
T.Morimoto,
K.Fukuyama,
H.Matsubara.
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Ref.
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J Biochem (tokyo), 1994,
115,
179-181.
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PubMed id
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