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PDBsum entry 2cbh
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Hydrolase (o-glycosyl)
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PDB id
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2cbh
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References listed in PDB file
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Key reference
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Title
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Determination of the three-Dimensional solution structure of the c-Terminal domain of cellobiohydrolase i from trichoderma reesei. A study using nuclear magnetic resonance and hybrid distance geometry-Dynamical simulated annealing.
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Authors
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J.Kraulis,
G.M.Clore,
M.Nilges,
T.A.Jones,
G.Pettersson,
J.Knowles,
A.M.Gronenborn.
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Ref.
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Biochemistry, 1989,
28,
7241-7257.
[DOI no: ]
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PubMed id
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Abstract
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The solution structure of a synthetic 36-residue polypeptide comprising the
C-terminal cellulose binding domain of cellobiohydrolase I (CT-CBH I) from
Trichoderma reesei was investigated by nuclear magnetic resonance (NMR)
spectroscopy. The 1H NMR spectrum was completely assigned in a sequential manner
by two-dimensional NMR techniques. A large number of stereospecific assignments
for beta-methylene protons, as well as ranges for the phi, psi, and chi 1
torsion angles, were obtained on the basis of sequential and intraresidue
nuclear Overhauser enhancement (NOE) and coupling constant data in combination
with a conformational data base search. The structure calculations were carried
out in an iterative manner by using the hybrid distance geometry-dynamical
simulated annealing method. This involved computing a series of initial
structures from a subset of the experimental data in order to resolve
ambiguities in the assignments of some NOE cross-peaks arising from chemical
shift degeneracy. Additionally, this permitted us to extend the stereospecific
assignments to the alpha-methylene protons of glycine using information on phi
torsion angles derived from the initial structure calculations. The final
experimental data set consisted of 554 interproton distance restraints, 24
restraints for 12 hydrogen bonds, and 33 phi, 24 psi, and 25 chi 1 torsion angle
restraints. CT-CBH I has two disulfide bridges whose pairing was previously
unknown. Analysis of structures calculated with all three possible combinations
of disulfide bonds, as well as without disulfide bonds, indicated that the
correct disulfide bridge pairing was 8-25 and 19-35. Forty-one structures were
computed with the 8-25 and 19-35 disulfide bridges, and the average atomic rms
difference between the individual structures and the mean structure obtained by
averaging their coordinates was 0.33 +/- 0.04 A for the backbone atoms and 0.52
+/- 0.06 A for all atoms. The protein has a wedgelike shape with an amphiphilic
character, one face being predominantly hydrophilic and the other mainly
hydrophobic. The principal element of secondary structure is made up of an
irregular triple-stranded antiparallel beta-sheet composed of residues 5-9 (beta
1), 24-28 (beta 2), and 33-36 (beta 3) in which strand beta 3 is hydrogen bonded
to the other two strands.(ABSTRACT TRUNCATED AT 400 WORDS)
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