1hvx
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(New page: 200px<br /><applet load="1hvx" size="450" color="white" frame="true" align="right" spinBox="true" caption="1hvx, resolution 2.0Å" /> '''BACILLUS STEAROTHERMO...)
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Revision as of 14:44, 20 November 2007
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BACILLUS STEAROTHERMOPHILUS ALPHA-AMYLASE
Overview
The crystal structure of a thermostable alpha-amylase from Bacillus, stearothermophilus (BSTA) has been determined at 2.0 A resolution. The, main-chain fold is almost identical to that of the known crystal structure, of Bacillus licheniformis alpha-amylase (BLA). BLA is known to be more, stable than BSTA. A structural comparison between the crystal structures, of BSTA and BLA showed significant differences that may account for the, difference in their thermostabilities, as follows. (i) The two-residue, insertion in BSTA, Ile181-Gly182, pushes away the spatially contacting, region including Asp207, which corresponds to Ca(2+)-coordinating Asp204, in BLA. As a result, Asp207 cannot coordinate the Ca(2+). (ii) BSTA, contains nine fewer hydrogen bonds than BLA, which costs about 12, kcal/mol. This tendency is prominent in the (beta/alpha)(8)-barrel, where, 10 fewer hydrogen bonds were observed in BSTA. BLA forms a denser hydrogen, bond network in the inter-helical region, which may stabilize, alpha-helices in the barrel. (iii) A few small voids observed in the, alpha-helical region of the (beta/alpha)(8)-barrel in BSTA decrease, inter-helical compactness and hydrophobic interactions. (iv) The, solvent-accessible surface area of charged residues in BLA is about two, times larger than that in BSTA.
About this Structure
1HVX is a Single protein structure of sequence from Geobacillus stearothermophilus with CA and NA as ligands. Active as Alpha-amylase, with EC number 3.2.1.1 Full crystallographic information is available from OCA.
Reference
Crystal structure of Bacillus stearothermophilus alpha-amylase: possible factors determining the thermostability., Suvd D, Fujimoto Z, Takase K, Matsumura M, Mizuno H, J Biochem (Tokyo). 2001 Mar;129(3):461-8. PMID:11226887
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