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PDBsum entry 1f9d
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Contents |
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* Residue conservation analysis
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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 the cellulase cel48f in complex with inhibitors and substrates give insights into its processive action.
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Authors
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G.Parsiegla,
C.Reverbel-Leroy,
C.Tardif,
J.P.Belaich,
H.Driguez,
R.Haser.
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Ref.
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Biochemistry, 2000,
39,
11238-11246.
[DOI no: ]
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PubMed id
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Abstract
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Cellulase Cel48F from Clostridium cellulolyticum was described as a processive
endo-cellulase. The active site is composed of a 25 A long tunnel which is
followed by an open cleft. During the processive action, the cellulose substrate
has to slide through the tunnel to continuously supply the leaving group site
with sugar residues after the catalytic cleavage. To study this processive
action in the tunnel, the native catalytic module of Cel48F and the inactive
mutant E55Q, have been cocrystallized with cellobiitol, two thio-oligosaccharide
inhibitors (PIPS-IG3 and IG4) and the cello-oligosaccharides cellobiose,
-tetraose and -hexaose. Seven sub-sites in the tunnel section of the active
center could be identified and three of the four previously reported sub-sites
in the open cleft section were reconfirmed. The sub-sites observed for the
thio-oligosaccharide inhibitors and oligosaccharides, respectively, were located
at two different positions in the tunnel corresponding to a shift in the chain
direction of about a half sugar subunit. These two positions have different
patterns of stacking interactions with aromatic residues present in the tunnel.
Multiple patterns are not observed in nonprocessive endo-cellulases, where only
one sugar position is favored by aromatic stacking. It is therefore proposed
that the aromatic residues serve as lubricating agents to reduce the sliding
barrier in the processive action.
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Secondary reference #1
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Title
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The crystal structure of the processive endocellulase celf of clostridium cellulolyticum in complex with a thiooligosaccharide inhibitor at 2.0 a resolution.
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Authors
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G.Parsiegla,
M.Juy,
C.Reverbel-Leroy,
C.Tardif,
J.P.Belaïch,
H.Driguez,
R.Haser.
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Ref.
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EMBO J, 1998,
17,
5551-5562.
[DOI no: ]
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PubMed id
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Figure 1.
Figure 1 Chemical structure of the thiooligosaccharide inhibitor
methyl 4-S-  -cellobiosyl-4-thio-cellobioside,
which is called IG4 in this article. The sugar subunits are
labelled from (A) to (D) from the non-reducing to the
O-methylated reducing end.
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Figure 7.
Figure 7 The (2F[o]-F[c]) electron density map contoured at the
1  level,
following the inhibitor molecules Inh1 (-6 to -4) and Inh2 (+1
to +4) from the tunnel to the end of the open cleft. It shows as
well the unexplained density at the gap between the inhibitor
molecules.
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The above figures are
reproduced from the cited reference
which is an Open Access publication published by Macmillan Publishers Ltd
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