Crystal structure of Bacillus stearothermophilus alpha-amylase: possible factors determining the thermostability.Suvd, D., Fujimoto, Z., Takase, K., Matsumura, M., Mizuno, H.
(2001) J.Biochem. 129: 461-468
- PubMed: 11226887
- PubMed Abstract:
- ACTIVATION OF BACILLUS LICHENIFORMIS ALPHA-AMYLASE THROUGH A DISORDER-->ORDER TRANSITION OF THE SUBSTRATE-BINDING SITE MEDIATED BY A CALCIUM-SODIUM-CALCIUM METAL TRIAD
Machius, M.,Declerck, N.,Huber, R.,Wiegand, R.
(1998) Structure 6: 281
- Crystal structure of calcium-depleted Bacillus licheniformis alpha-amylase at 2.2 A resolution.
Machius, M.,Wiegand, G.,Huber, R.
(1995) J.Mol.Biol. 246: 545
- Purification, crystallization and preliminary X-ray crystallographic study of alpha-amylase from Bacillus stearothermophilus.
Suvd, D.,Takase, K.,Fujiimoto, Z.,Matsumura, M.,Mizuno, H.
(2000) Acta Crystallogr.,Sect.D 56: 200
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-amyl ...
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.
Institute of Applied Biochemistry, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan. email@example.com