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| {{STRUCTURE_2g3m| PDB=2g3m | SCENE= }} | | {{STRUCTURE_2g3m| PDB=2g3m | SCENE= }} |
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| '''Crystal structure of the Sulfolobus solfataricus alpha-glucosidase MalA'''
| | ===Crystal structure of the Sulfolobus solfataricus alpha-glucosidase MalA=== |
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| ==Overview==
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| The crystal structure of alpha-glucosidase MalA from Sulfolobus solfataricus has been determined at 2.5Angstrom resolution. It provides a structural model for enzymes representing the major specificity in glycoside hydrolase family 31 (GH31), including alpha-glucosidases from higher organisms, involved in glycogen degradation and glycoprotein processing. The structure of MalA shows clear differences from the only other structure known from GH31, alpha-xylosidase YicI. MalA and YicI share only 23% sequence identity. Although the two enzymes display a similar domain structure and both form hexamers, their structures differ significantly in quaternary organization: MalA is a dimer of trimers, YicI a trimer of dimers. MalA and YicI also differ in their substrate specificities, as shown by kinetic measurements on model chromogenic substrates. In addition, MalA has a clear preference for maltose (Glc-alpha1,4-Glc), whereas YicI prefers isoprimeverose (Xyl-alpha1,6-Glc). The structural origin of this difference occurs in the -1 subsite where MalA residues Asp251 and Trp284 could interact with OH6 of the substrate. The structure of MalA in complex with beta-octyl-glucopyranoside has been determined. It reveals Arg400, Asp87, Trp284, Met321 and Phe327 as invariant residues forming the +1 subsite in the GH31 alpha-glucosidases. Structural comparisons with other GH families suggest that the GH31 enzymes belong to clan GH-D. | | The line below this paragraph, {{ABSTRACT_PUBMED_16580018}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 16580018 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_16580018}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Multidomain protein]] | | [[Category: Multidomain protein]] |
| [[Category: Retaining mechanism]] | | [[Category: Retaining mechanism]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 04:39:02 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 16:49:36 2008'' |
