1HVX

BACILLUS STEAROTHERMOPHILUS ALPHA-AMYLASE

Summary for 1HVX

• Entry DOI: 10.2210/pdb1hvx/pdb
• Descriptor: ALPHA-AMYLASE, CALCIUM ION, SODIUM ION, ... (4 entities in total)
• Functional Keywords: hydrolase, glycosyltransferase, alpha-amylase, starch degradation, alpha-1, 4-glucan-4-glucanohydrolase, thermostability
• Biological source: Geobacillus stearothermophilus
• Total number of polymer chains: 1
• Total formula weight: 59033.71

Authors

Suvd, D.,Fujimoto, Z.,Takase, K.,Matsumura, M.,Mizuno, H. (deposition date: 2001-01-08, release date: 2001-01-31, Last modification date: 2024-03-13)

Primary citation

Suvd, D.,Fujimoto, Z.,Takase, K.,Matsumura, M.,Mizuno, H.
Crystal structure of Bacillus stearothermophilus alpha-amylase: possible factors determining the thermostability.
J.Biochem., 129:461-468, 2001

PubMed Abstract: 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.

PubMed: 11226887
DOI: 10.1093/oxfordjournals.jbchem.a002878

Experimental method

X-RAY DIFFRACTION (2 Å)