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| - | [[Image:1b1y.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1b1y| PDB=1b1y | SCENE= }} | | {{STRUCTURE_1b1y| PDB=1b1y | SCENE= }} |
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| - | '''SEVENFOLD MUTANT OF BARLEY BETA-AMYLASE'''
| + | ===SEVENFOLD MUTANT OF BARLEY BETA-AMYLASE=== |
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| - | ==Overview==
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| - | The three-dimensional structure of the sevenfold mutant of barley beta-amylase (BBA-7s) with increased thermostability was determined by X-ray crystallography. The enzyme was purified as a single component and crystallized by a hanging drop method in the presence of 14 % PEG 6000. The crystals belong to space group P43212 with cell dimensions a=b=72.11 A, c=250.51 A. The diffraction data up to 2.5 A were collected after soaking the crystal in 100 mM maltose with Rsym of 8.6 %. The structure was determined by a molecular replacement method using soybean beta-amylase (SBA) as a search model and refined to an R-factor of 18.7 %. The final model included 500 amino acid residues, 141 water molecules and three glucose residues, which were located at subsites 1-2 and 4 in the active site. The r.m.s. distance of 485 Calpha atoms between BBA-7s and SBA was 0.62 A. Out of the seven mutated amino acids, four (Ser295Ala, Ile297Val, Ser351Pro and Ala376Ser) were substitutions from the common residues with SBA to the thermostable forms. A comparison of the structures of BBA-7s and SBA indicated that the side-chain of Ser376 makes new hydrogen bonds to the main-chain of an adjacent beta-strand, and that the side-chains of Val297 reduce an unfavorable interaction between the side-chains of Ala314. The mutation of Ser295Ala breaks the hydrogen bond between Ser295 OG and Tyr195 OH, which seems to be the reason for the unoccupied glucose residue at subsite 3. The tandem mutations at 350-352 including substitutions to two Pro residues suggested the reduction of main-chain entropy in the unfolded structure of this solvent-exposed protruded loop.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_9918723}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 9918723 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_9918723}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Yoon, H J.]] | | [[Category: Yoon, H J.]] |
| | [[Category: Yoshigi, N.]] | | [[Category: Yoshigi, N.]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 10:57:44 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 18:03:06 2008'' |
Revision as of 15:03, 30 June 2008
Template:STRUCTURE 1b1y
SEVENFOLD MUTANT OF BARLEY BETA-AMYLASE
Template:ABSTRACT PUBMED 9918723
About this Structure
1B1Y is a Single protein structure of sequence from Hordeum vulgare. Full crystallographic information is available from OCA.
Reference
The crystal structure of the sevenfold mutant of barley beta-amylase with increased thermostability at 2.5 A resolution., Mikami B, Yoon HJ, Yoshigi N, J Mol Biol. 1999 Jan 22;285(3):1235-43. PMID:9918723
Page seeded by OCA on Mon Jun 30 18:03:06 2008
