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Peptide conformational changes induced by tryptophan–phosphocholine interactions in a micelle
Author(s) -
Neidigh Jonathan W.,
Andersen Niels H.
Publication year - 2002
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.10272
Subject(s) - chemistry , micelle , phosphocholine , tryptophan , peptide , residue (chemistry) , aqueous solution , membrane , stereochemistry , crystallography , biophysics , organic chemistry , biochemistry , phospholipid , amino acid , phosphatidylcholine , biology
Sodium dodecylsulfate (SDS) and dodecylphosphocholine (DPC) micelles are often used to mimic the membrane‐ or receptor‐bound states of peptides in NMR studies. From the present examination of a 26‐residue analog of exendin‐4 (TrEX4) by NMR and CD in water, aqueous 30% trifluoroethanol (TFE), and bound to both SDS and DPC micelles, it is clear that these two lipid micelles can yield very different peptide structures. The Trp‐cage fold (also observed in 30% TFE) is present when TrEX4 is bound to SDS micelles; however, tertiary structure is absent in the presence of DPC micelles. The loss of tertiary structure is attributed to an energetically favorable interaction (estimated as 2–3 kcal/mol) of the tryptophan side chain with the phosphocholine head groups. These dramatic structural differences suggest that care must be taken when using either SDS or DPC to mimic the membrane‐ or receptor‐bound states. © 2002 Wiley Periodicals, Inc. Biopolymers 65: 354–361, 2002