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PDBsum entry 1i2f
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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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Hydrophobic core manipulations in ribonuclease t1.
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Authors
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S.De vos,
J.Backmann,
M.Prévost,
J.Steyaert,
R.Loris.
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Ref.
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Biochemistry, 2001,
40,
10140-10149.
[DOI no: ]
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PubMed id
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Abstract
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Differential scanning calorimetry, urea denaturation, and X-ray crystallography
were combined to study the structural and energetic consequences of refilling an
engineered cavity in the hydrophobic core of RNase T1 with CH(3), SH, and OH
groups. Three valines that cluster together in the major hydrophobic core of T1
were each replaced with Ala, Ser, Thr, and Cys. Compared to the wild-type
protein, all these mutants reduce the thermodynamic stability of the enzyme
considerably. The relative order of stability at all three positions is as
follows: Val > Ala approximately equal to Thr > Ser. The effect of
introducing a sulfhydryl group is more variable. Surprisingly, a Val --> Cys
mutation in a hydrophobic environment can be as or even more destabilizing than
a Val --> Ser mutation. Furthermore, our results reveal that the penalty for
introducing an OH group into a hydrophobic cavity is roughly the same as the
gain obtained from filling the cavity with a CH(3) group. The inverse
equivalence of the behavior of hydroxyl and methyl groups seems to be crucial
for the unique three-dimensional structure of the proteins. The importance of
negative design elements in this context is highlighted.
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