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Peptide conformational changes induced by tryptophan-phosphocholine interactions in a micelle
Jonathan W Neidigh1, Niels H Andersen
1Department of Chemistry, University of Washington, Seattle 98195, USA.
Biopolymers
|October 22, 2002
Summary
Sodium dodecylsulfate (SDS) and dodecylphosphocholine (DPC) micelles yield different peptide structures in NMR studies. DPC micelles disrupt Trp-cage folds, unlike SDS micelles, due to tryptophan side chain interactions.
Area of Science:
- Biochemistry
- Structural Biology
- Nuclear Magnetic Resonance (NMR) Spectroscopy
Background:
- Sodium dodecylsulfate (SDS) and dodecylphosphocholine (DPC) micelles are common models for membrane-bound peptides in NMR.
- Understanding peptide behavior in these micelles is crucial for interpreting receptor-bound states.
Purpose of the Study:
- To investigate the structural differences of a peptide analog (TrEX4) when bound to SDS versus DPC micelles.
- To determine how these different micellar environments affect peptide folding and tertiary structure.
Main Methods:
- Nuclear Magnetic Resonance (NMR) spectroscopy was used to analyze peptide structure.
- Circular Dichroism (CD) spectroscopy was employed to assess secondary structure.
- Experiments were conducted in water, 30% trifluoroethanol (TFE), and with SDS and DPC micelles.
Main Results:
- TrEX4 adopted a Trp-cage fold in 30% TFE and when bound to SDS micelles.
- Tertiary structure was absent when TrEX4 was bound to DPC micelles.
- Tryptophan side chain interaction with DPC phosphocholine head groups was identified as the cause for structure loss.
Conclusions:
- SDS and DPC micelles induce significantly different peptide structures.
- DPC micelles can disrupt peptide tertiary structure due to specific head group interactions.
- Caution is advised when using SDS or DPC to model membrane- or receptor-bound peptide states.