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| [[Image:2amg.gif|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_2amg| PDB=2amg | SCENE= }} | | {{STRUCTURE_2amg| PDB=2amg | SCENE= }} |
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| '''STRUCTURE OF HYDROLASE (GLYCOSIDASE)'''
| | ===STRUCTURE OF HYDROLASE (GLYCOSIDASE)=== |
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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_9126844}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 9126844 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_9126844}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Hydrolase]] | | [[Category: Hydrolase]] |
| [[Category: Signal]] | | [[Category: Signal]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 19:13:10 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 20:33:20 2008'' |
