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| | {{STRUCTURE_1e40| PDB=1e40 | SCENE= }} | | {{STRUCTURE_1e40| PDB=1e40 | SCENE= }} |
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| - | '''TRIS/MALTOTRIOSE COMPLEX OF CHIMAERIC AMYLASE FROM B. AMYLOLIQUEFACIENS AND B. LICHENIFORMIS AT 2.2A'''
| + | ===TRIS/MALTOTRIOSE COMPLEX OF CHIMAERIC AMYLASE FROM B. AMYLOLIQUEFACIENS AND B. LICHENIFORMIS AT 2.2A=== |
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| - | ==Overview==
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| - | Several chimeric alpha-amylases genes were constructed by an in vivo recombination technique from the Bacillus amyloliquefaciens and Bacillus licheniformis genes. One of the fusion amylases (hereafter BA2), consisting of residues 1-300 from B. amyloliquefaciens and 301-483 from B. licheniformis, has been extensively studied by X-ray crystallography at resolutions between 2.2 and 1.7 A. The 3-dimensional structure of the native enzyme was solved by multiple isomorphous replacement, and refined at a resolution of 1.7 A. It consists of 483 amino acids, organized similarly to the known B. lichiniformis alpha-amylase structure [Machius et al. (1995) J. Mol. Biol. 246, 545-559], but features 4 bound calcium ions. Two of these form part of a linear cluster of three ions, the central ion being attributed to sodium. This cluster lies at the junction of the A and B domains with one calcium of the cluster structurally equivalent to the major Ca(2+) binding site of fungal alpha-amylases. The third calcium ion is found at the interface of the A and C domains. BA2 contains a fourth calcium site, not observed in the B. licheniformis alpha-amylase structure. It is found on the C domain where it bridges the two beta-sheets. Three acid residues (Glu261, Asp328, and Asp231) form an active site similar to that seen in other amylases. In the presence of TRIS buffer, a single molecule of TRIS occupies the -1 subsite of the enzyme where it is coordinated by the three active-center carboxylates. Kinetic data reveal that BA2 displays properties intermediate to those of its parents. Data for crystals soaked in maltooligosaccharides reveal the presence of a maltotriose binding site on the N-terminal face of the (beta/alpha)(8) barrel of the molecule, not previously described for any alpha-amylase structure, the biological function of which is unclear. Data for a complex soaked with the tetrasaccharide inhibitor acarbose, at 1.9 A, reveal a decasaccharide moiety, spanning the -7 to +3 subsites of the enzyme. The unambiguous presence of three unsaturated rings in the (2)H(3) half-chair/(2)E envelope conformation, adjacent to three 6-deoxypyranose units, clearly demonstrates synthesis of this acarbose-derived decasaccharide by a two-step transglycosylation mechanism.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_10924103}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 10924103 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_10924103}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Maltotriose]] | | [[Category: Maltotriose]] |
| | [[Category: Tri]] | | [[Category: Tri]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 14:38:04 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 00:06:55 2008'' |
Revision as of 21:06, 30 June 2008
Template:STRUCTURE 1e40
TRIS/MALTOTRIOSE COMPLEX OF CHIMAERIC AMYLASE FROM B. AMYLOLIQUEFACIENS AND B. LICHENIFORMIS AT 2.2A
Template:ABSTRACT PUBMED 10924103
About this Structure
1E40 is a Single protein structure of sequence from Bacillus amyloliquefaciens. Full crystallographic information is available from OCA.
Reference
Structural analysis of a chimeric bacterial alpha-amylase. High-resolution analysis of native and ligand complexes., Brzozowski AM, Lawson DM, Turkenburg JP, Bisgaard-Frantzen H, Svendsen A, Borchert TV, Dauter Z, Wilson KS, Davies GJ, Biochemistry. 2000 Aug 8;39(31):9099-107. PMID:10924103
Page seeded by OCA on Tue Jul 1 00:06:55 2008
