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PDBsum entry 1vjs
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References listed in PDB file
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Key reference
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Title
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Crystal structure of thermostable alpha-Amylase from bacillus licheniformis refined at 1.7 a resolution.
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Authors
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K.Y.Hwang,
H.K.Song,
C.Chang,
J.Lee,
S.Y.Lee,
K.K.Kim,
S.Choe,
R.M.Sweet,
S.W.Suh.
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Ref.
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Mol Cells, 1997,
7,
251-258.
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PubMed id
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Abstract
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alpha-Amylases (alpha-1,4-glucan-4-glucanohydrolase, E.C.3.2.1.1) catalyze the
cleavage of alpha-1, 4-glucosidic linkages of starch components, glycogen, and
various oligosaccharides. Thermostable alpha-amylases from Bacillus species are
of great industrial importance in the production of corn syrup or dextrose.
Thermostable alpha-amylase from Bacillus licheniformis, a monomeric enzyme with
molecular mass of 55,200 Da (483 amino acid residues), shows a remarkable heat
stability. This enzyme provides an attractive model for investigating the
structural basis for thermostability of proteins. The three-dimensional
structure of thermostable alpha-amylase from Bacillus licheniformis has been
determined by the multiple isomorphous replacement method of X-ray
crystallography. The structure has been refined to a crystallographic R-factor
of 19.9% for 58,601 independent reflections with F0 > 2 sigma F0 between 8.0
and 1.7 A resolution, with root mean square deviations of 0.013 A from ideal
bond lengths and 1.72 degrees from ideal bond angles. The final model consists
of 469 amino acid residues and 294 water molecules. Missing from the model are
the N- and C-termini and the segment between Trp182 and Asn192. Like other
alpha-amylases, the polypeptide chain folds into three distinct domains. The
first domain (domain A), consisting of 291 residues (from residue 3 to 103 and
207 to 396), forms a (beta/alpha)8-barrel structure. The second domain (domain
B), consisting of residues 104 to 206, is inserted between the third beta-strand
and the third alpha-helix of domain A. The third C-terminal domain (domain C),
consisting of residues 397 to 482, folds into an eight-stranded antiparallel
beta-barrel. Neither calcium ion nor chloride ion is located near the active
site. This study reveals the architecture of the thermostable alpha-amylase from
Bacillus licheniformis. By homology with other alpha-amylases, important active
site residues can be identified as Asp231, Glu261, and Asp328, which are all
located at the C-terminal end of the central (beta/alpha)8-barrel. Since many of
the stabilizing and destabilizing mutations obtained so far fall in domain B or
at its border, this region of the enzyme appears to be important for
thermostability. The factors responsible for the remarkable thermostability of
this enzyme may be increased ionic interactions, reduced surface area, and
increased packing interactions in the interior.
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Secondary reference #1
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Title
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Crystallization and a preliminary X-Ray crystallographic study of alpha-Amylase from bacillus licheniformis.
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Authors
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S.Y.Lee,
S.Kim,
R.M.Sweet,
S.W.Suh.
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Ref.
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Arch Biochem Biophys, 1991,
291,
255-257.
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PubMed id
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