7taa

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(New page: 200px<br /><applet load="7taa" size="450" color="white" frame="true" align="right" spinBox="true" caption="7taa, resolution 1.98&Aring;" /> '''FAMILY 13 ALPHA AMYL...)
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caption="7taa, resolution 1.98&Aring;" />
'''FAMILY 13 ALPHA AMYLASE IN COMPLEX WITH ACARBOSE'''<br />
'''FAMILY 13 ALPHA AMYLASE IN COMPLEX WITH ACARBOSE'''<br />
==Overview==
==Overview==
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The three-dimensional structure of the Aspergillus oryzae alpha-amylase, (TAKA-amylase), in complex with the inhibitor acarbose, has been, determined by X-ray crystallography at a resolution of 1. 98 A. The, tetrasaccharide inhibitor is present as a hexasaccharide presumably, resulting from a transglycosylation event. The hexasaccharide occupies the, -3 to +3 subsites of the enzyme, consistent with the known number of, subsites determined by kinetic studies, with the acarbose unit itself in, the -1 to +3 subsites of the enzyme. The transition state mimicking, unsaturated pseudo-saccharide occupies the -1 subsite as expected and is, present in a distorted 2H3 half-chair conformation. Careful refinement, plus extremely well-resolved unbiased electron density suggest that the, hexasaccharide represents a genuine transglycosylation product, but the, possibility that this apparent species results from an overlapping network, of tetrasaccharides is also discussed. Catalysis by alpha-amylase involves, the hydrolysis of the alpha-1,4 linkages in amylose with a net retention, of the anomeric configuration, via a double-displacement mechanism, as, originally outlined by Koshland [Koshland, D. E. (1953) Biol. Rev. 28, 416-336]. The enzymatic acid/base and nucleophile, residues Glu230 and, Asp206, respectively, are appropriately positioned for catalysis in this, complex, and the hexasaccharide species allows mapping of all the, noncovalent interactions between protein and ligand through the enzyme's, six subsites.
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The three-dimensional structure of the Aspergillus oryzae alpha-amylase (TAKA-amylase), in complex with the inhibitor acarbose, has been determined by X-ray crystallography at a resolution of 1. 98 A. The tetrasaccharide inhibitor is present as a hexasaccharide presumably resulting from a transglycosylation event. The hexasaccharide occupies the -3 to +3 subsites of the enzyme, consistent with the known number of subsites determined by kinetic studies, with the acarbose unit itself in the -1 to +3 subsites of the enzyme. The transition state mimicking unsaturated pseudo-saccharide occupies the -1 subsite as expected and is present in a distorted 2H3 half-chair conformation. Careful refinement plus extremely well-resolved unbiased electron density suggest that the hexasaccharide represents a genuine transglycosylation product, but the possibility that this apparent species results from an overlapping network of tetrasaccharides is also discussed. Catalysis by alpha-amylase involves the hydrolysis of the alpha-1,4 linkages in amylose with a net retention of the anomeric configuration, via a double-displacement mechanism, as originally outlined by Koshland [Koshland, D. E. (1953) Biol. Rev. 28, 416-336]. The enzymatic acid/base and nucleophile, residues Glu230 and Asp206, respectively, are appropriately positioned for catalysis in this complex, and the hexasaccharide species allows mapping of all the noncovalent interactions between protein and ligand through the enzyme's six subsites.
==About this Structure==
==About this Structure==
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7TAA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aspergillus_oryzae Aspergillus oryzae] with ABC and CA as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Alpha-amylase Alpha-amylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.1 3.2.1.1] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=7TAA OCA].
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7TAA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aspergillus_oryzae Aspergillus oryzae] with <scene name='pdbligand=ABC:'>ABC</scene> and <scene name='pdbligand=CA:'>CA</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Alpha-amylase Alpha-amylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.1 3.2.1.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=7TAA OCA].
==Reference==
==Reference==
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[[Category: Aspergillus oryzae]]
[[Category: Aspergillus oryzae]]
[[Category: Single protein]]
[[Category: Single protein]]
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[[Category: Brzozowski, A.M.]]
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[[Category: Brzozowski, A M.]]
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[[Category: Davies, G.J.]]
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[[Category: Davies, G J.]]
[[Category: ABC]]
[[Category: ABC]]
[[Category: CA]]
[[Category: CA]]
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[[Category: taka]]
[[Category: taka]]
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''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 15:11:33 2007''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 19:17:34 2008''

Revision as of 17:17, 21 February 2008

Image:7taa.gif

7taa, resolution 1.98Å

Drag the structure with the mouse to rotate

FAMILY 13 ALPHA AMYLASE IN COMPLEX WITH ACARBOSE

Overview

The three-dimensional structure of the Aspergillus oryzae alpha-amylase (TAKA-amylase), in complex with the inhibitor acarbose, has been determined by X-ray crystallography at a resolution of 1. 98 A. The tetrasaccharide inhibitor is present as a hexasaccharide presumably resulting from a transglycosylation event. The hexasaccharide occupies the -3 to +3 subsites of the enzyme, consistent with the known number of subsites determined by kinetic studies, with the acarbose unit itself in the -1 to +3 subsites of the enzyme. The transition state mimicking unsaturated pseudo-saccharide occupies the -1 subsite as expected and is present in a distorted 2H3 half-chair conformation. Careful refinement plus extremely well-resolved unbiased electron density suggest that the hexasaccharide represents a genuine transglycosylation product, but the possibility that this apparent species results from an overlapping network of tetrasaccharides is also discussed. Catalysis by alpha-amylase involves the hydrolysis of the alpha-1,4 linkages in amylose with a net retention of the anomeric configuration, via a double-displacement mechanism, as originally outlined by Koshland [Koshland, D. E. (1953) Biol. Rev. 28, 416-336]. The enzymatic acid/base and nucleophile, residues Glu230 and Asp206, respectively, are appropriately positioned for catalysis in this complex, and the hexasaccharide species allows mapping of all the noncovalent interactions between protein and ligand through the enzyme's six subsites.

About this Structure

7TAA is a Single protein structure of sequence from Aspergillus oryzae with and as ligands. Active as Alpha-amylase, with EC number 3.2.1.1 Full crystallographic information is available from OCA.

Reference

Structure of the Aspergillus oryzae alpha-amylase complexed with the inhibitor acarbose at 2.0 A resolution., Brzozowski AM, Davies GJ, Biochemistry. 1997 Sep 9;36(36):10837-45. PMID:9283074

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