1e6r: Difference between revisions
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[[Category: inhibitor allosamidin]] | [[Category: inhibitor allosamidin]] | ||
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CHITINASE B FROM SERRATIA MARCESCENS WILDTYPE IN COMPLEX WITH INHIBITOR ALLOSAMIDIN
OverviewOverview
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.
About this StructureAbout this Structure
1E6R is a Single protein structure of sequence from Serratia marcescens with SO4 and AMI as ligands. Structure known Active Site: AMA. Full crystallographic information is available from OCA.
ReferenceReference
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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