1j0h
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Crystal structure of Bacillus stearothermophilus neopullulanase
OverviewOverview
Crystal structures of Bacillus stearothermophilus TRS40 neopullulanase and, its complexes with panose, maltotetraose and isopanose were determined at, resolutions of 1.9, 2.4, 2.8 and 3.2A, respectively. Since the latter two, carbohydrates are substrates of this enzyme, a deactivated mutant at the, catalytic residue Glu357-->Gln was used for complex crystallization. The, structures were refined at accuracies with r.m.s. deviations of bond, lengths and bond angles ranging from 0.005A to 0.008A and 1.3 degrees to, 1.4 degrees, respectively. The active enzyme forms a dimer in the, crystalline state and in solution. The monomer enzyme is composed of four, domains, N, A, B and C, and has a (beta/alpha)(8)-barrel in domain A. The, active site lies between domain A and domain N from the other monomer. The, results show that dimer formation makes the active-site cleft narrower, than those of ordinary alpha-amylases, which may contribute to the unique, substrate specificity of this enzyme toward both alpha-1,4 and, alpha-1,6-glucosidic linkages. This specificity may be influenced by the, subsite structure. Only subsites -1 and -2 are commonly occupied by the, product and substrates, suggesting that equivocal recognition occurs at, the other subsites, which contributes to the wide substrate specificity of, this enzyme.
About this StructureAbout this Structure
1J0H is a Single protein structure of sequence from Geobacillus stearothermophilus with CL and CA as ligands. Active as Neopullulanase, with EC number 3.2.1.135 Full crystallographic information is available from OCA.
ReferenceReference
Three-dimensional structure and substrate binding of Bacillus stearothermophilus neopullulanase., Hondoh H, Kuriki T, Matsuura Y, J Mol Biol. 2003 Feb 7;326(1):177-88. PMID:12547200
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