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| - | [[Image:1e6n.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1e6n| PDB=1e6n | SCENE= }} | | {{STRUCTURE_1e6n| PDB=1e6n | SCENE= }} |
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| - | '''CHITINASE B FROM SERRATIA MARCESCENS INACTIVE MUTANT E144Q IN COMPLEX WITH N-ACETYLGLUCOSAMINE-PENTAMER'''
| + | ===CHITINASE B FROM SERRATIA MARCESCENS INACTIVE MUTANT E144Q IN COMPLEX WITH N-ACETYLGLUCOSAMINE-PENTAMER=== |
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| - | ==Overview==
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| - | Chitinase B (ChiB) from Serratia marcescens is a family 18 exo-chitinase whose catalytic domain has a TIM-barrel fold with a tunnel-shaped active site. We have solved structures of three ChiB complexes that reveal details of substrate binding, substrate-assisted catalysis, and product displacement. The structure of an inactive ChiB mutant (E144Q) complexed with a pentameric substrate (binding in subsites -2 to +3) shows closure of the "roof" of the active site tunnel. It also shows that the sugar in the -1 position is distorted to a boat conformation, thus providing structural evidence in support of a previously proposed catalytic mechanism. The structures of the active enzyme complexed to allosamidin (an analogue of a proposed reaction intermediate) and of the active enzyme soaked with pentameric substrate show events after cleavage of the glycosidic bond. The latter structure shows reopening of the roof of the active site tunnel and enzyme-assisted product displacement in the +1 and +2 sites, allowing a water molecule to approach the reaction center. Catalysis is accompanied by correlated structural changes in the core of the TIM barrel that involve conserved polar residues whose functions were hitherto unknown. These changes simultaneously contribute to stabilization of the reaction intermediate and alternation of the pKa of the catalytic acid during the catalytic cycle.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_11481469}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 11481469 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_11481469}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Glycosidase]] | | [[Category: Glycosidase]] |
| | [[Category: Hydrolase]] | | [[Category: Hydrolase]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 14:43:52 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 00:14:23 2008'' |
Revision as of 21:14, 30 June 2008
Template:STRUCTURE 1e6n
CHITINASE B FROM SERRATIA MARCESCENS INACTIVE MUTANT E144Q IN COMPLEX WITH N-ACETYLGLUCOSAMINE-PENTAMER
Template:ABSTRACT PUBMED 11481469
About this Structure
1E6N is a Single protein structure of sequence from Serratia marcescens. Full crystallographic information is available from OCA.
Reference
Structural insights into the catalytic mechanism of a family 18 exo-chitinase., van Aalten DM, Komander D, Synstad B, Gaseidnes S, Peter MG, Eijsink VG, Proc Natl Acad Sci U S A. 2001 Jul 31;98(16):8979-84. PMID:11481469
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