1cwy
From Proteopedia
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| , resolution 2.00Å | |||||||
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| Activity: | 4-alpha-glucanotransferase, with EC number 2.4.1.25 | ||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
CRYSTAL STRUCTURE OF AMYLOMALTASE FROM THERMUS AQUATICUS, A GLYCOSYLTRANSFERASE CATALYSING THE PRODUCTION OF LARGE CYCLIC GLUCANS
Overview
Amylomaltase is involved in the metabolism of starch, one of the most important polysaccharides in nature. A unique feature of amylomaltase is its ability to catalyze the formation of cyclic amylose. In contrast to the well studied cyclodextrin glucanotransferases (CGTases), which synthesize cycloamylose with a ring size (degree of polymerization or DP) of 6-8, the amylomaltase from Thermus aquaticus produces cycloamyloses with a DP of 22 and higher. The crystal structure of amylomaltase from Thermus aquaticus was determined to 2.0 A resolution. It is a member of the alpha-amylase superfamily of enzymes, whose core structure consists of a (beta, alpha)(8) barrel. In amylomaltase, the 8-fold symmetry of this barrel is disrupted by several insertions between the barrel strands. The largest insertions are between the third and fifth barrel strands, where two insertions form subdomain B1, as well as between the second and third barrel strands, forming the alpha-helical subdomain B2. Whereas part of subdomain B1 is also present in other enzyme structures of the alpha-amylase superfamily, subdomain B2 is unique to amylomaltase. Remarkably, the C-terminal domain C, which is present in all related enzymes of the alpha-amylase family, is missing in amylomaltase. Amylomaltase shows a similar arrangement of the catalytic side-chains (two Asp residues and one Glu residue) as in previously characterized members of the alpha-amylase superfamily, indicating similar mechanisms of the glycosyl transfer reaction. In amylomaltase, a conserved loop of around eight amino acid residues is partially shielding the active center. This loop, which is well conserved among other amylomaltases, may sterically hinder the formation of small cyclic products.
About this Structure
1CWY is a Single protein structure of sequence from Thermus aquaticus. Full crystallographic information is available from OCA.
Reference
Crystal structure of amylomaltase from thermus aquaticus, a glycosyltransferase catalysing the production of large cyclic glucans., Przylas I, Tomoo K, Terada Y, Takaha T, Fujii K, Saenger W, Strater N, J Mol Biol. 2000 Feb 25;296(3):873-86. PMID:10677288
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