Summary for 2AMG
| Entry DOI | 10.2210/pdb2amg/pdb |
| Descriptor | 1,4-ALPHA-D-GLUCAN MALTOTETRAHYDROLASE, CALCIUM ION (3 entities in total) |
| Functional Keywords | hydrolase, glycosidase, carbohydrate metabolism |
| Biological source | Pseudomonas stutzeri |
| Cellular location | Secreted: P13507 |
| Total number of polymer chains | 1 |
| Total formula weight | 46661.98 |
| Authors | Morishita, Y.,Hasegawa, K.,Matsuura, Y.,Kubota, M.,Sakai, S.,Katsube, Y. (deposition date: 1996-12-23, release date: 1997-04-01, Last modification date: 2024-06-05) |
| Primary citation | Morishita, Y.,Hasegawa, K.,Matsuura, Y.,Katsube, Y.,Kubota, M.,Sakai, S. Crystal structure of a maltotetraose-forming exo-amylase from Pseudomonas stutzeri. J.Mol.Biol., 267:661-672, 1997 Cited by PubMed Abstract: The three-dimensional structure of an exo-type alpha-amylase from Pseudomonas stutzeri which degrades starch from its non-reducing end to produce maltotetraose has been determined by X-ray structure analysis. The catalytic domain of this enzyme (G4-2), whose structure was determined, is a product of spontaneous limited proteolysis in culture broth. It has 429 amino acid residues and a molecular mass of 47,200, and crystallizes in ammonium sulfate solution at pH 7.5. The structure was elucidated by the multiple isomorphous replacement method and refined at 2.0 A resolution, resulting in a final R-factor of 0.178 for significant reflections with a root-mean-square deviation from ideality in bond distances of 0.013 A. The polypeptide chain of this molecule folds into three domains; the first with a (beta/alpha)8 barrel structure, the second with an excursed part from the first one, and the third with five-stranded antiparallel beta-sheets. The active cleft is formed on the C-terminal side of the beta-sheets in the (beta/alpha)8 barrel as in the known endo-type alpha-amylases. A histidine side-chain nitrogen ND1 is coordinated to one of the bound calcium ion. The recognition site of the non-reducing end of the amylose that determines exo-wise degradation is presumed to be at one end of this cleft where there is a disordered loop consisting of the 66th to 72nd residues, and a loop carrying an aspartic acid (Asp160). These structural features may be responsible for the binding of the non-reducing end of the substrate amylose. PubMed: 9126844DOI: 10.1006/jmbi.1996.0887 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2 Å) |
Structure validation
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