7TAA
FAMILY 13 ALPHA AMYLASE IN COMPLEX WITH ACARBOSE
Summary for 7TAA
| Entry DOI | 10.2210/pdb7taa/pdb |
| Descriptor | TAKA AMYLASE, MODIFIED ACARBOSE HEXASACCHARIDE, CALCIUM ION, ... (4 entities in total) |
| Functional Keywords | hydrolase, glycosyl hydrolase, taka, amylase, acarbose |
| Biological source | Aspergillus oryzae |
| Total number of polymer chains | 1 |
| Total formula weight | 53503.94 |
| Authors | Davies, G.J.,Brzozowski, A.M. (deposition date: 1997-10-06, release date: 1998-11-25, Last modification date: 2024-10-23) |
| Primary citation | Brzozowski, A.M.,Davies, G.J. Structure of the Aspergillus oryzae alpha-amylase complexed with the inhibitor acarbose at 2.0 A resolution. Biochemistry, 36:10837-10845, 1997 Cited by PubMed Abstract: The three-dimensional structure of the Aspergillus oryzae alpha-amylase (TAKA-amylase), in complex with the inhibitor acarbose, has been determined by X-ray crystallography at a resolution of 1. 98 A. The tetrasaccharide inhibitor is present as a hexasaccharide presumably resulting from a transglycosylation event. The hexasaccharide occupies the -3 to +3 subsites of the enzyme, consistent with the known number of subsites determined by kinetic studies, with the acarbose unit itself in the -1 to +3 subsites of the enzyme. The transition state mimicking unsaturated pseudo-saccharide occupies the -1 subsite as expected and is present in a distorted 2H3 half-chair conformation. Careful refinement plus extremely well-resolved unbiased electron density suggest that the hexasaccharide represents a genuine transglycosylation product, but the possibility that this apparent species results from an overlapping network of tetrasaccharides is also discussed. Catalysis by alpha-amylase involves the hydrolysis of the alpha-1,4 linkages in amylose with a net retention of the anomeric configuration, via a double-displacement mechanism, as originally outlined by Koshland [Koshland, D. E. (1953) Biol. Rev. 28, 416-336]. The enzymatic acid/base and nucleophile, residues Glu230 and Asp206, respectively, are appropriately positioned for catalysis in this complex, and the hexasaccharide species allows mapping of all the noncovalent interactions between protein and ligand through the enzyme's six subsites. PubMed: 9283074DOI: 10.1021/bi970539i PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.98 Å) |
Structure validation
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