1ppi

THE ACTIVE CENTER OF A MAMMALIAN ALPHA-AMYLASE. THE STRUCTURE OF THE COMPLEX OF A PANCREATIC ALPHA-AMYLASE WITH A CARBOHYDRATE INHIBITOR REFINED TO 2.2 ANGSTROMS RESOLUTION

spinqualitylabelsall models 1ppi, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1ppi is a 1 chain structure with sequence from Sus scrofa. The February 2006 RCSB PDB Molecule of the Month feature on Alpha-amylase by David S. Goodsell is 10.2210/rcsb_pdb/mom_2006_2. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.2Å Ligands: BGC, CA, CL, DAF, GLC, PRD_900001 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function AMYP_PIG Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed An X-ray structure analysis of a crystal of pig pancreatic alpha-amylase (EC 3.2.1.1) that was soaked with acarbose (a pseudotetrasaccharide alpha-amylase inhibitor) showed electron density corresponding to five fully occupied subsites in the active site. The crystal structure was refined to an R-factor of 15.3%, with a root mean square deviation in bond distances of 0.015 A. The model includes all 496 residues of the enzyme, one calcium ion, one chloride ion, 393 water molecules, and five bound sugar rings. The pseudodisaccharide acarviosine that is the essential structural unit responsible for the activity of all inhibitors of the acarbose type was located at the catalytic center. The carboxylic oxygens of the catalytically competent residues Glu233 and Asp300 form hydrogen bonds with the "glycosidic" NH group of the acarviosine group. The third residue of the catalytic triad Asp197 is located on the opposite side of the inhibitor binding cleft with one of its carbonyl oxygens at a 3.3-A distance from the anomeric carbon C-1 of the inhibitor center. Binding of inhibitor induces structural changes at the active site of the enzyme. A loop region between residues 304 and 309 moves in toward the bound saccharide, the resulting maximal mainchain movement being 5 A for His305. The side chain of residue Asp300 rotates upon inhibitor binding and makes strong van der Waals contacts with the imidazole ring of His299. Four histidine residues (His101, His201, His299, and His305) are found to be hydrogen-bonded with the inhibitor. Many protein-inhibitor hydrogen bond interactions are observed in the complex structure, as is clear hydrophobic stacking of aromatic residues with the inhibitor surface. The chloride activator ion and structural calcium ion are hydrogen-bonded via their ligands and water molecules to the catalytic residues. The active center of a mammalian alpha-amylase. Structure of the complex of a pancreatic alpha-amylase with a carbohydrate inhibitor refined to 2.2-A resolution.,Qian M, Haser R, Buisson G, Duee E, Payan F Biochemistry. 1994 May 24;33(20):6284-94. PMID:8193143 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Amylase 3D structures

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