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Title
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A cavity-containing mutant of T4 lysozyme is stabilized by buried benzene.
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Authors
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A.E.Eriksson,
W.A.Baase,
J.A.Wozniak,
B.W.Matthews.
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Ref.
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Nature, 1992,
355,
371-373.
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PubMed id
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Abstract
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The hydrophobic cores of proteins are generally well packed, with few cavities.
Mutations in which a bulky buried residue such as leucine or phenylalanine is
replaced with a small residue such as alanine can create cavities in the core of
a protein (our unpublished results). The sizes and shapes of such cavities can
vary substantially depending on factors such as local geometry, whether or not a
cavity already exists at the site of substitution, and the degree to which the
protein structure relaxes to occupy the space vacated by the substituted
residue. We show by crystallographic and thermodynamic analysis that the cavity
created by the replacement Leu 99----Ala in T4 lysozyme is large enough to bind
benzene and that ligand binding increases the melting temperature of the protein
by 6.0 degrees C at pH 3.0. Benzene does not, however, bind to the cavity
created by the Phe 153----Ala replacement. The results show that cavities can be
engineered in proteins and suggest that such cavities might be tailored to bind
specific ligands. The binding of benzene at an internal site 7 A from the
molecular surface also illustrates the dynamic nature of proteins, even in
crystals.
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