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PDBsum entry 1c43
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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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Effect of foreign n-Terminal residues on the conformational stability of human lysozyme.
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Authors
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K.Takano,
K.Tsuchimori,
Y.Yamagata,
K.Yutani.
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Ref.
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Eur J Biochem, 1999,
266,
675-682.
[DOI no: ]
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PubMed id
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Abstract
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To minutely understand the effect of foreign N-terminal residues on the
conformational stability of human lysozyme, five mutant proteins were
constructed: two had Met or Ala in place of the N-terminal Lys residue (K1M and
K1A, respectively), and others had one additional residue, Met, Gly or Pro, to
the N-terminal Lys residue (Met(-1), Gly(-1) and Pro(-1), respectively). The
thermodynamic parameters for denaturation of these mutant proteins were examined
by differential scanning calorimetry and were compared with that of the
wild-type protein. Three mutants with the extra residue were significantly
destabilized: the changes in unfolding Gibbs energy (DeltaDeltaG) were -9.1 to
-12.2 kJ.mol-1. However, the stability of two single substitutions at the
N-terminal slightly decreased; the DeltaDeltaG values were only -0.5 to -2.5
kJ.mol-1. The results indicate that human lysozyme is destabilized by an
expanded N-terminal residue. The crystal structural analyses of K1M, K1A and
Gly(-1) revealed that the introduction of a residue at the N-terminal of human
lysozyme caused the destruction of hydrogen bond networks with ordered water
molecules, resulting in the destabilization of the protein.
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Figure 2.
Fig. 2. Typical excess heat capacity curves of (a) the
wild-type (b) K1A and (c) Met(-1) of human lysozyme at pH 2.72,
2.77 and 2.65, respectively. The increments of excess heat
capacity are 10 kJ·mol^-1·K^-1.
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Figure 3.
Fig. 3. Stereodrawings of (A) the K1M (B) K1A and (C)
Gly(-1) structures in the vicinity of the N-terminal of human
lysozyme. Solvent water molecules are drawn as crossed circles.
Broken lines represent hydrogen bonds. The structure was
generated with the program ORTEP [42].
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The above figures are
reprinted
by permission from the Federation of European Biochemical Societies:
Eur J Biochem
(1999,
266,
675-682)
copyright 1999.
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Secondary reference #1
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Title
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Contribution of hydrophobic residues to the stability of human lysozyme: calorimetric studies and X-Ray structural analysis of the five isoleucine to valine mutants.
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Authors
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K.Takano,
K.Ogasahara,
H.Kaneda,
Y.Yamagata,
S.Fujii,
E.Kanaya,
M.Kikuchi,
M.Oobatake,
K.Yutani.
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Ref.
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J Mol Biol, 1995,
254,
62-76.
[DOI no: ]
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PubMed id
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Figure 2.
Figure 2. Typical excess heat capacity curves of the
mutant human lysozyme (I106V) at pH 2.70 (a), 2.92 (b),
3.04 (c), 3.10 (d), and 3.14 (e). The increments of excess
heat capacity were 10 kJ/mol K.
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Figure 5.
Figure 5. Stereo drawings (Johnson, 1976) showing the mutant structure in the vicinity of the mutation sites. The
wild-type (open bonds) and mutant structures (filled bonds) are superimposed. (a) I23V; (b) I56V; (c) I59V; (d) I89V;
and (e) I106V. Solvent water molecules are drawn as cross-circles. Broken lines indicate hydrogen bonds.
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The above figures are
reproduced from the cited reference
with permission from Elsevier
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