A Fourier Transform Infrared Spectroscopy Technique to Study Peptide Self-Assembly

In This Article

Abstract

Source: Neves, R., et al. Synthesis and Characterization of 1,2-Dithiolane Modified Self-Assembling Peptides. J. Vis. Exp. (2018)

This video demonstrates the self-assembly of amyloid peptides into a beta sheet-rich supramolecular structure using Fourier transform infrared spectroscopy. An infrared beam is passed through a crystal with a high refractive index, and energy absorption across the interface of the crystal and the sample is recorded. The secondary structures of the sample proteins are identified by analyzing their characteristic absorption peaks at specific regions of the infrared spectrum, which aids in identifying the formation of the supramolecular assembly.

Protocol

1. Characterization of Supramolecular Self-Assembly Structures

Formation of Amyloid Fibers
1. To prepare a self-assembly solution, weigh out 1 mg of the peptide powder using an analytical balance. Dissolve into a mixture (pH 7.5) of 20% acetonitrile and 10 mM (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) in a 1.5 mL microcentrifuge tube, to a final concentration of 1 mg/mL peptide assembly mixture. Vortex the assembly solution and leave it to assemble at room temperature.
Spectroscopic Characterization of Amyloid Fibers
1. Follow the peptide assembly process via Fourier-trans....

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Results

FTIR spectra 1627/1676 cm⁻¹ (A), CD spectrum 190-270 nm (B), TEM nanofibers 100 nm scale (C).
Figure 1. Supramolecular characterization of 1,2-dithiolane modified peptide. (A) FT-IR of 1 mg/mL 1,2-dithiolane-KLVFFAQ-NH₂ fibers assembled in 10mM HEPES, pH 7.5 in 20% CH₃CN. The peak at 1627 cm^-1 is consistent with the peptide.......