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PDBsum entry 3b9e
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References listed in PDB file
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Key reference
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Title
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Crystal structures of vibrio harveyi chitinase a complexed with chitooligosaccharides: implications for the catalytic mechanism.
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Authors
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C.Songsiriritthigul,
S.Pantoom,
A.H.Aguda,
R.C.Robinson,
W.Suginta.
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Ref.
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J Struct Biol, 2008,
162,
491-499.
[DOI no: ]
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PubMed id
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Abstract
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This research describes four X-ray structures of Vibrio harveyi chitinase A and
its catalytically inactive mutant (E315M) in the presence and absence of
substrates. The overall structure of chitinase A is that of a typical family-18
glycosyl hydrolase comprising three distinct domains: (i) the amino-terminal
chitin-binding domain; (ii) the main catalytic (alpha/beta)(8) TIM-barrel
domain; and (iii) the small (alpha+beta) insertion domain. The catalytic cleft
of chitinase A has a long, deep groove, which contains six chitooligosaccharide
ring-binding subsites (-4)(-3)(-2)(-1)(+1)(+2). The binding cleft of the
ligand-free E315M is partially blocked by the C-terminal (His)(6)-tag.
Structures of E315M-chitooligosaccharide complexes display a linear conformation
of pentaNAG, but a bent conformation of hexaNAG. Analysis of the final
2F(o)-F(c) omit map of E315M-NAG6 reveals the existence of the linear
conformation of the hexaNAG at a lower occupancy with respect to the bent
conformation. These crystallographic data provide evidence that the interacting
sugars undergo conformational changes prior to hydrolysis by the wild-type
enzyme.
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