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PDBsum entry 2oaw
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Structural protein
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PDB id
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2oaw
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References listed in PDB file
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Key reference
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Title
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Structural and thermodynamic studies of bergerac-Sh3 chimeras.
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Authors
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L.V.Gushchina,
A.G.Gabdulkhakov,
S.V.Nikonov,
P.L.Mateo,
V.V.Filimonov.
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Ref.
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Biophys Chem, 2009,
139,
106-115.
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PubMed id
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Abstract
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Bergerac-type chimeras of spectrin SH3 were designed by extending a beta-hairpin
by eight amino acids so that the extension protruded from the domain body like a
"nose" being exposed to the solvent. A calorimetric study of several
Bergerac-SH3 variants was carried out over a wide range of pH values and protein
concentrations and the three-dimensional structure of one of them, SHH, was
determined. X-ray studies confirmed that the nose had a well defined
beta-structure whilst the chimera formed a stable tetramer within the crystal
unit because of four tightly packed noses. In the pH range of 4-7 the
heat-induced unfolding of some chimeras was complex and concentration dependent,
whilst at pH values below 3.5, low protein concentrations of all the chimeras
studied, including SHH, seemed to obey a monomolecular two-state unfolding
model. The best set of data was obtained for the SHA variant, the unfolding heat
effects of which were systematically higher than those of the WT protein (about
16.4 kJ/mol at 323 K), which may be close to the upper limit of the enthalpy
gain due to 10 residue beta-hairpin folding. At the same time, the chimeras with
high nose stability, which, like SHH, have a hydrophobic (IVY) cluster on their
surface, showed a lower apparent unfolding heat effect, much closer to that of
the WT protein. The possible reasons for this difference are discussed.
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