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PDBsum entry 1st7
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Transport protein
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PDB id
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1st7
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References listed in PDB file
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Key reference
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Title
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Different secondary structure elements as scaffolds for protein folding transition states of two homologous four-Helix bundles.
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Authors
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K.Teilum,
T.Thormann,
N.R.Caterer,
H.I.Poulsen,
P.H.Jensen,
J.Knudsen,
B.B.Kragelund,
F.M.Poulsen.
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Ref.
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Proteins, 2005,
59,
80-90.
[DOI no: ]
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PubMed id
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Abstract
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Comparison of the folding processes for homologue proteins can provide valuable
information about details in the interactions leading to the formation of the
folding transition state. Here the folding kinetics of 18 variants of yACBP and
3 variants of bACBP have been studied by Phi-value analysis. In combination with
Phi-values from previous work, detailed insight into the transition states for
folding of both yACBP and bACBP has been obtained. Of the 16 sequence positions
that have been studied in both yACBP and bACBP, 5 (V12, I/L27, Y73, V77, and
L80) have high Phi-values and appear to be important for the transition state
formation in both homologues. Y31, A34, and A69 have high Phi-values only in
yACBP, while F5, A9, and I74 have high Phi-values only in bACBP. Thus,
additional interactions between helices A2 and A4 appear to be important for the
transition state of yACBP, whereas additional interactions between helices A1
and A4 appear to be important for the transition state of bACBP. To examine
whether these differences could be assigned to different packing of the residues
in the native state, a solution structure of yACBP was determined by NMR. Small
changes in the packing of the hydrophobic side-chains, which strengthen the
interactions between helices A2 and A4, are observed in yACBP relative to bACBP.
It is suggested that different structure elements serve as scaffolds for the
folding of the 2 ACBP homologues.
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Figure 5.
Figure 5. Effect of changes in  G[UN]
on  [U]
(top panel) and on m[eq,kin] (  ),
m[u] (  ),
and m[f] (  linear
fits, and the dotted lines are 95% prediction limits for the
fits.
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Figure 8.
Figure 8.
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The above figures are
reprinted
by permission from John Wiley & Sons, Inc.:
Proteins
(2005,
59,
80-90)
copyright 2005.
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