1bvz
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(New page: 200px<br /><applet load="1bvz" size="450" color="white" frame="true" align="right" spinBox="true" caption="1bvz, resolution 2.6Å" /> '''ALPHA-AMYLASE II (TVA...)
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Revision as of 09:50, 20 November 2007
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ALPHA-AMYLASE II (TVAII) FROM THERMOACTINOMYCES VULGARIS R-47
Overview
The crystal structure of Thermoactinomyces vulgaris R-47 alpha-Amylase II, (TVAII) has been determined by multiple isomorphous replacement at 2.6 A, resolution. TVAII was crystallized in an orthorhombic system with the, space group P212121 and the cell dimensions a=118.5 A, b=119.5 A, c=114.5, A. There are two molecules in an asymmetric unit, related by the, non-crystallographic 2-fold symmetry. Diffraction data were collected at, 113 K and the cell dimensions reduced to a=114.6 A, b=117.9 A, c=114.2 A, and the model was refined against 7.0-2.6 A resolution data giving an, R-factor of 0.204 (Rfree=0.272). The final model consists of 1170 amino, acid residues (two molecules) and 478 water molecules with good chemical, geometry. TVAII has three domains, A, B, and C, like other alpha-amylases., Domain A with a (beta/alpha)8 barrel structure and domain C with a, beta-sandwich structure are very similar to those found in other, alpha-amylases. Additionally, TVAII has an extra domain N composed of 121, amino acid residues at the N-terminal site, which has a beta-barrel-like, structure consisting of seven antiparallel beta-strands. Domain N is one, of the driving forces in the formation of the dimer structure of TVAII, but its role in the enzyme activity is still not clear. TVAII does not, have the Ca2+ binding site that connects domains A and B in other, alpha-amylases, rather the NZ atom of Lys299 of TVAII serves as the, connector between these domains. TVAII can hydrolyze cyclodextrins and, pullulan as well as starch. Based on a structural comparison with the, complex between a mutant cyclodextrin glucanotransferase and a, beta-cyclodextrin derivative, Phe286 located at domain B is considered the, residue most likely to recognize the hydrophobic cavity of cyclodextrins., The active-site cleft of TVAII is wider and shallower than that of other, alpha-amylases, and seems to be suitable for the binding of pullulan which, is expected not to adopt the helical structure of amylose.
About this Structure
1BVZ is a Single protein structure of sequence from Thermoactinomyces vulgaris. Active as Neopullulanase, with EC number 3.2.1.135 Full crystallographic information is available from OCA.
Reference
Crystal structure of Thermoactinomyces vulgaris R-47 alpha-amylase II (TVAII) hydrolyzing cyclodextrins and pullulan at 2.6 A resolution., Kamitori S, Kondo S, Okuyama K, Yokota T, Shimura Y, Tonozuka T, Sakano Y, J Mol Biol. 1999 Apr 16;287(5):907-21. PMID:10222200
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