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PDBsum entry 1bsb
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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 structural analysis of mutations in the hydrophobic cores of barnase.
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Authors
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A.M.Buckle,
K.Henrick,
A.R.Fersht.
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Ref.
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J Mol Biol, 1993,
234,
847-860.
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PubMed id
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Abstract
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We have solved and analysed the crystal structures of five mutants in the
hydrophobic core of barnase to investigate the structural basis for the
contribution of hydrophobic residues and side-chain packing to the stability of
globular proteins. In case ease, an amino acid side-chain has been replaced with
one of smaller volume. The overall structures of four Ile-->Val mutants
(residues 51, 76, 88 and 96) and one Leu-->Val mutant (residue 89) are all
isomorphous with the wild-type structure. The magnitude and nature of structural
shifts in the three hydrophobic core regions of barnase depend on the local
environment of the substitution site, but have some features in common. (1)
Side-chain atoms move to a greater extent than do main-chain atoms. (2)
Repacking at the substitution site is achieved by either a rigid body shift of
side-chain atoms (for Ile-->Val76 and Ile-->Val96 mutants), or by a
combination of a side-chain shift and rotation (for Ile-->Val51 and
Ile-->Val88 mutants). The mutated residue moves to the greatest extent, and
generally in the direction of the created cavity (the largest atomic shift is
0.9 A, for Ile-->Val51). The space left behind from such shifts is not seen
to be filled by neighbouring side-chains. (3) Where a cavity remains after
mutation, it does not contain any solvent molecules. (4) There is no correlation
between the extent of structural movements and the atomic temperature factors of
atoms that have moved. (5) Structural movements are not large enough to disrupt
hydrogen bonding. Valine 88, in the Ile-->Val88 mutant, is disordered and the
electron density suggests several side-chain conformations. The reduction in the
volumes of the cavities introduced upon mutation, due to collapse of the
surrounding structure, ranges from 11% (Ile-->Val96) to 90% (Ile-->Val51).
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Secondary reference #1
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Title
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The folding of an enzyme. Ii. Substructure of barnase and the contribution of different interactions to protein stability.
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Authors
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L.Serrano,
J.T.Kellis,
P.Cann,
A.Matouschek,
A.R.Fersht.
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Ref.
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J Mol Biol, 1992,
224,
783-804.
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PubMed id
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Secondary reference #2
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Title
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Molecular structure of a new family of ribonucleases.
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Authors
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Y.Mauguen,
R.W.Hartley,
E.J.Dodson,
G.G.Dodson,
G.Bricogne,
C.Chothia,
A.Jack.
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Ref.
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Nature, 1982,
297,
162-164.
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PubMed id
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