Related Experiment Video
Updated: Jul 1, 2026
11:19
Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels
Published on: July 4, 2016
Characterization of a conformationally sensitive TOAC spin-labeled substance P.
Aaron M Shafer1, Clovis R Nakaie, Xavier Deupi
1Department of Biochemistry & Molecular Medicine, University of California, Davis, CA 95616, United States.
Peptides
|September 9, 2008
Summary
Researchers used spin-labeled substance P peptides to study neurokinin-1 receptor binding dynamics. The 4-TOAC analog showed robust binding, providing insights into receptor activation and conformational changes.
Area of Science:
- Biochemistry
- Molecular Biology
- Biophysics
Background:
- G-protein coupled receptors (GPCRs) are crucial drug targets.
- Substance P is a peptide agonist for the neurokinin-1 receptor (NK1R).
- Understanding ligand-receptor interactions is key to drug development.
Purpose of the Study:
- To investigate the binding and conformational dynamics of spin-labeled substance P analogs at the NK1R.
- To assess the impact of TOAC substitution on peptide affinity, signaling, and receptor states.
- To utilize EPR spectroscopy for real-time monitoring of peptide-receptor interactions.
Main Methods:
- Synthesis of substance P analogs with TOAC at positions 4 and 9.
- Measurement of peptide affinity and receptor signaling potency.
- Electron Paramagnetic Resonance (EPR) spectroscopy to probe peptide dynamics.
- Molecular dynamics simulations to model peptide conformations.
Main Results:
- 4-TOAC substance P exhibited comparable affinity to native substance P, while 9-TOAC substance P showed significantly lower affinity.
- Both analogs activated receptor signaling, but with reduced potency for the 9-TOAC variant.
- EPR detected binding of both analogs, with 4-TOAC substance P showing dynamics indicative of different receptor states (high and low affinity).
- Molecular modeling provided insights into how TOAC substitution affects peptide backbone structure.
Conclusions:
- TOAC-labeled substance P analogs are valuable tools for studying NK1R dynamics.
- The position of TOAC substitution influences peptide affinity and receptor interaction.
- 4-TOAC substance P can report on distinct NK1R conformational states during activation.
