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PDBsum entry 1dn3
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De novo protein
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PDB id
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1dn3
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References listed in PDB file
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Key reference
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Title
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Involvement of electrostatic interactions in the mechanism of peptide folding induced by sodium dodecyl sulfate binding.
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Authors
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R.Montserret,
M.J.Mcleish,
A.Böckmann,
C.Geourjon,
F.Penin.
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Ref.
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Biochemistry, 2000,
39,
8362-8373.
[DOI no: ]
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PubMed id
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Abstract
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Sodium dodecyl sulfate (SDS) has consistently been shown to induce secondary
structure, particularly alpha-helices, in polypeptides, and is commonly used to
model membrane and other hydrophobic environments. However, the precise
mechanism by which SDS induces these conformational changes remains unclear. To
examine the role of electrostatic interactions in this mechanism, we have
designed two hydrophilic, charged amphipathic alpha-helical peptides, one basic
(QAPAYKKAAKKLAES) and the other acidic (QAPAYEEAAEELAKS), and their structures
were studied by CD and NMR. The design of the peptides is based on the sequence
of the segment of residues 56-70 of human platelet factor 4 [PF4(56-70),
QAPLYKKIIKKLLES]. Both peptides were unstructured in water, and in the presence
of neutral, zwitterionic, or cationic detergents. However, in SDS at neutral pH,
the basic peptide folded into an alpha-helix. By contrast, the pH needed to be
lowered to 1.8 before alpha-helix formation was observed for the acidic peptide.
Strong, attractive electrostatic interactions, between the anionic groups of SDS
and the cationic groups of the lysines, appeared to be necessary to initiate the
folding of the basic peptide. NMR analysis showed that the basic peptide was
fully embedded in SDS-peptide micelles, and that its three-dimensional
alpha-helical structure could be superimposed on that of the native structure of
PF4(56-70). These results enabled us to propose a working model of the basic
peptide-SDS complex, and a mechanism for SDS-induced alpha-helical folding. This
study demonstrates that, while the folding of peptides is mostly driven by
hydrophobic effects, electrostatic interactions play a significant role in the
formation and the stabilization of SDS-induced structure.
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