Related Experiment Video
Updated: Jul 2, 2026

Contrast-Matching Detergent in Small-Angle Neutron Scattering Experiments for Membrane Protein Structural Analysis and Ab Initio Modeling
Published on: October 21, 2018
Secondary structure transitions and aggregation induced in dynorphin neuropeptides by the detergent sodium dodecyl
Loïc Hugonin1, Andreas Barth, Astrid Gräslund
1Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-10691, Stockholm, Sweden.
Abstract:
Dynorphins, endogeneous opioid neuropeptides, function as ligands to the opioid kappa receptors and also induce non-opioid effects in neurons, probably related to direct membrane interactions. We have characterized the structure transitions of dynorphins (big dynorphin, dynorphin A and dynorphin B) induced by the detergent sodium dodecyl sulfate (SDS). In SDS titrations monitored by circular dichroism, we observed secondary structure conversions of the peptides from random coil to alpha-helix with a highly aggregated intermediate. As determined by Fourier transform infrared spectroscopy, this intermediate exhibited beta-sheet structure for dynorphin B and big dynorphin. In contrast, aggregated dynorphin A was alpha-helical without considerable beta-sheet content. Hydrophobicity analysis indicates that the YGGFLRR motif present in all dynorphins is prone to be inserted in the membrane. Comparing big dynorphin with dynorphin A and dynorphin B, we suggest that the potent neurotoxicity of big dynorphin could be related to the combination of amino acid sequences and secondary structure propensities of dynorphin A and dynorphin B, which may generate a synergistic effect for big dynorphin membrane perturbing properties. The induced aggregated alpha-helix of dynorphin A is also correlated with membrane perturbations, whereas the beta-sheet of dynorphin B does not correlate with membrane perturbations.
Related Concept Videos
Protein Folding
Protein Folding
Protein Structure Is Critical to Its Biological Function
Proteins perform a wide range of biological functions such as catalyzing chemical reactions, providing...
Detergent Purification of Membrane Proteins
Protein and Protein Structure
A protein's shape is critical to its function. For example, an enzyme can...
Protein Organization
Protein Organization
The primary structure of a protein is its amino acid sequence.

