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Contents |
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* Residue conservation analysis
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Enzyme class:
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E.C.3.2.1.98
- Glucan 1,4-alpha-maltohexaosidase.
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Reaction:
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Hydrolysis of 1,4-alpha-D-glucosidic linkages in amylaceous polysaccharides so as to remove successive maltohexaose residues from the non-reducing chain ends.
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Gene Ontology (GO) functional annotation
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Cellular component
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extracellular region
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1 term
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Biological process
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metabolic process
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2 terms
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Biochemical function
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catalytic activity
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8 terms
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Acta Crystallograph Sect F Struct Biol Cryst Commun
62:849-854
(2006)
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PubMed id:
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Structure of Bacillus halmapalus alpha-amylase crystallized with and without the substrate analogue acarbose and maltose.
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L.Lyhne-Iversen,
T.J.Hobley,
S.G.Kaasgaard,
P.Harris.
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ABSTRACT
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Recombinant Bacillus halmapalus alpha-amylase (BHA) was studied in two different
crystal forms. The first crystal form was obtained by crystallization of BHA at
room temperature in the presence of acarbose and maltose; data were collected at
cryogenic temperature to a resolution of 1.9 A. It was found that the crystal
belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 47.0, b =
73.5, c = 151.1 A. A maltose molecule was observed and found to bind to BHA and
previous reports of the binding of a nonasaccharide were confirmed. The second
crystal form was obtained by pH-induced crystallization of BHA in a
MES-HEPES-boric acid buffer (MHB buffer) at 303 K; the solubility of BHA in MHB
has a retrograde temperature dependency and crystallization of BHA was only
possible by raising the temperature to at least 298 K. Data were collected at
cryogenic temperature to a resolution of 2.0 A. The crystal belonged to space
group P2(1)2(1)2(1), with unit-cell parameters a = 38.6, b = 59.0, c = 209.8 A.
The structure was solved using molecular replacement. The maltose-binding site
is described and the two structures are compared. No significant changes were
seen in the structure upon binding of the substrates.
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Selected figure(s)
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Figure 3.
The tertiary structure of B. halmapalus [alpha]-amylase in
the complexed crystal form. The N-terminal
([beta]/[alpha])[8]-barrel domain is shown in blue, the loop
domain in turquoise and the C-terminal [beta]-sheet domain in
red. The nonasaccharide and maltose are shown as yellow sticks
and the two glucose molecules are shown as green sticks. Metal
ions are shown as spheres. The figure was produced using PyMOL
(DeLano, 2002[triangle]). Acta Crystallogr Sect F Struct Biol
Cryst Commun. 2006 September 1; 62(Pt 9): 849–854. Published
online 2006 August 26. doi: 10.1107/S174430910603096X. Copyright
[copyright] International Union of Crystallography 2006
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Figure 5.
Maltose (red) shown in the complexed crystal structure
(blue). The uncomplexed crystal form is superimposed (green).
The illustration was produced using O (Jones et al.,
1991[triangle]). Acta Crystallogr Sect F Struct Biol Cryst
Commun. 2006 September 1; 62(Pt 9): 849–854. Published online
2006 August 26. doi: 10.1107/S174430910603096X. Copyright
[copyright] International Union of Crystallography 2006
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The above figures are
reprinted
from an Open Access publication published by the IUCr:
Acta Crystallograph Sect F Struct Biol Cryst Commun
(2006,
62,
849-854)
copyright 2006.
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Figures were
selected
by an automated process.
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Links
