1qhp
From Proteopedia
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FIVE-DOMAIN ALPHA-AMYLASE FROM BACILLUS STEAROTHERMOPHILUS, MALTOSE COMPLEX
Overview
The three-dimensional structure of the Bacillus stearothermophilus, "maltogenic" alpha-amylase, Novamyl, has been determined by X-ray, crystallography at a resolution of 1.7 A. Unlike conventional, alpha-amylases from glycoside hydrolase family 13, Novamyl exhibits the, five-domain structure more usually associated with cyclodextrin, glycosyltransferase. Complexes of the enzyme with both maltose and the, inhibitor acarbose have been characterized. In the maltose complex, two, molecules of maltose are found in the -1 to -2 and +2 to +3 subsites of, the active site, with two more on the C and E domains. The C-domain, maltose occupies a position identical to one previously observed in the, Bacillus circulans CGTase structure [Lawson, C. L., et al. (1994) J. Mol., Biol. 236, 590-600], suggesting that the C-domain plays a genuine, biological role in saccharide binding. In the acarbose-maltose complex, the tetrasaccharide inhibitor acarbose is found as an extended, hexasaccharide species, bound in the -3 to +3 subsites. The transition, state mimicking pseudosaccharide is bound in the -1 subsite of the enzyme, in a 2H3 half-chair conformation, as expected. The active site of Novamyl, lies in an open gully, fully consistent with its ability to perform, internal cleavage via an endo as opposed to an exo activity.
About this Structure
1QHP is a Single protein structure of sequence from Geobacillus stearothermophilus with MAL, SO4 and CA as ligands. Active as Glucan 1,4-alpha-maltohydrolase, with EC number 3.2.1.133 Full crystallographic information is available from OCA.
Reference
X-ray structure of Novamyl, the five-domain "maltogenic" alpha-amylase from Bacillus stearothermophilus: maltose and acarbose complexes at 1.7A resolution., Dauter Z, Dauter M, Brzozowski AM, Christensen S, Borchert TV, Beier L, Wilson KS, Davies GJ, Biochemistry. 1999 Jun 29;38(26):8385-92. PMID:10387084
Page seeded by OCA on Wed Nov 21 00:42:48 2007
