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PDBsum entry 1ckh
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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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Contribution of intra- And intermolecular hydrogen bonds to the conformational stability of human lysozyme(,).
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Authors
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K.Takano,
Y.Yamagata,
J.Funahashi,
Y.Hioki,
S.Kuramitsu,
K.Yutani.
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Ref.
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Biochemistry, 1999,
38,
12698-12708.
[DOI no: ]
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PubMed id
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Abstract
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In globular proteins, there are intermolecular hydrogen bonds between protein
and water molecules, and between water molecules, which are bound with the
proteins, in addition to intramolecular hydrogen bonds. To estimate the
contribution of these hydrogen bonds to the conformational stability of a
protein, the thermodynamic parameters for denaturation and the crystal
structures of five Thr to Val and five Thr to Ala mutant human lysozymes were
determined. The denaturation Gibbs energy (DeltaG) of Thr to Val and Thr to Ala
mutant proteins was changed from 4.0 to -5.6 kJ/mol and from 1.6 to -6.3 kJ/mol,
respectively, compared with that of the wild-type protein. The contribution of
hydrogen bonds to the stability (DeltaDeltaG(HB)) of the Thr and other mutant
human lysozymes previously reported was extracted from the observed stability
changes (DeltaDeltaG) with correction for changes in hydrophobicity and side
chain conformational entropy between the wild-type and mutant structures. The
estimation of the DeltaDeltaG(HB) values of all mutant proteins after removal of
hydrogen bonds, including protein-water hydrogen bonds, indicates a favorable
contribution of the intra- and intermolecular hydrogen bonds to the protein
stability. The net contribution of an intramolecular hydrogen bond
(DeltaG(HB[pp])), an intermolecular one between protein and ordered water
molecules (DeltaG(HB[pw])), and an intermolecular one between ordered water
molecules (DeltaG(HB[ww])) could be estimated to be 8. 5, 5.2, and 5.0 kJ/mol,
respectively, for a 3 A long hydrogen bond. This result shows the different
contributions to protein stability of intra- and intermolecular hydrogen bonds.
The entropic cost due to the introduction of a water molecule (DeltaG(H)()2(O))
could be also estimated to be about 8 kJ/mol.
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