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| - | [[Image:1ut9.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1ut9| PDB=1ut9 | SCENE= }} | | {{STRUCTURE_1ut9| PDB=1ut9 | SCENE= }} |
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| - | '''STRUCTURAL BASIS FOR THE EXOCELLULASE ACTIVITY OF THE CELLOBIOHYDROLASE CBHA FROM C. THERMOCELLUM'''
| + | ===STRUCTURAL BASIS FOR THE EXOCELLULASE ACTIVITY OF THE CELLOBIOHYDROLASE CBHA FROM C. THERMOCELLUM=== |
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| - | ==Overview==
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| - | Numerous bacterial and fungal organisms have evolved elaborate sets of modular glycoside hydrolases and similar enzymes aimed at the degradation of polymeric carbohydrates. Presently, on the basis of sequence similarity catalytic modules of these enzymes have been classified into 90 families. Representatives of a particular family display similar fold and catalytic mechanisms. However, within families distinctions occur with regard to enzymatic properties and type of activity against carbohydrate chains. Cellobiohydrolase CbhA from Clostridium thermocellum is a large seven-modular enzyme with a catalytic module belonging to family 9. In contrast to other representatives of that family possessing only endo- and, in few cases, endo/exo-cellulase activities, CbhA is exclusively an exocellulase. The crystal structures of the combination of the immunoglobulin-like module and the catalytic module of CbhA (Ig-GH9_CbhA) and that of an inactive mutant Ig-GH9_CbhA(E795Q) in complex with cellotetraose (CTT) are reported here. The detailed analysis of these structures reveals that, while key catalytic residues and overall fold are conserved in this enzyme and those of other family 9 glycoside hydrolases, the active site of GH9_CbhA is blocked off after the -2 subsite. This feature which is created by an extension and altered conformation of a single loop region explains the inability of the active site of CbhA to accommodate a long cellulose chain and to cut it internally. This altered loop region is responsible for the exocellulolytic activity of the enzyme.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_14756552}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 14756552 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_14756552}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Family 9]] | | [[Category: Family 9]] |
| | [[Category: Glycoside hydrolase]] | | [[Category: Glycoside hydrolase]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 11:39:27 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 20:21:01 2008'' |
Revision as of 17:21, 28 July 2008
Template:STRUCTURE 1ut9
STRUCTURAL BASIS FOR THE EXOCELLULASE ACTIVITY OF THE CELLOBIOHYDROLASE CBHA FROM C. THERMOCELLUM
Template:ABSTRACT PUBMED 14756552
About this Structure
1UT9 is a Single protein structure of sequence from Clostridium thermocellum. Full crystallographic information is available from OCA.
Reference
Structural basis for the exocellulase activity of the cellobiohydrolase CbhA from Clostridium thermocellum., Schubot FD, Kataeva IA, Chang J, Shah AK, Ljungdahl LG, Rose JP, Wang BC, Biochemistry. 2004 Feb 10;43(5):1163-70. PMID:14756552
Page seeded by OCA on Mon Jul 28 20:21:01 2008
