Circular dichroism (CD) spectroscopy measures difference in the absorption of left-handed polarized light versus right-handed polarized light that arises due to structural asymmetry. The absence of regular structure results in zero CD intensity, while an ordered structure results in a spectrum that can contain both positive and negative signals.

CD can be used for:

• Determination if a protein is folded
• Characterization of  secondary structure (α-helix, β-sheet)
• Detection of changes in structure upon mutagenesis
• Studying conformational stability of proteins by varying:
  • pH
  • denaturant concentration (urea, guanidinium chloride )
  • temperature
  • buffers components
  • stabilizers
• Detection of Changes in the conformation of a protein upon protein:protein interaction

Characterization of secondary structure is probably the most used CD spectroscopy application. Secondary structure can be identified in the "far-UV" spectral region (190-250 nm). Thepeptide bond is the chromophore, and it is possible to detect a signal if the protein is in a specific secondary structural conformation (α-helix, β-sheet).

Alpha-helix, beta-sheet, and random coil structures each give rise to a characteristic shape and magnitude of the CD spectrum. Like all spectroscopic techniques, the CD signal reflects an average of the entire molecular population.

CD Spectroscopy requirements:

Far-UV CD spectra require between 100 µl- 700 µl of ~ 3-10 µM protein solution, in any buffer which does not have high absorbance in this region of the spectrum.

Substances not optimal for CD: DTT (high concentrations only), imidazole, TritonX-100.

Accessories:

1. Pelitier temperature control.
2. Automated Titration Systems allow chemical denaturation, and ligand binding studies in a completely unattended mode.
3. Bio-Logic: SFM-20; two-channel stop-flow setup for kinetics measurements.

Circular Dichroism

Please e-mail Mandar Naik to gain the ability to book an instrument through our calendar system.

To view the availability of this instrument, please click on the link below:

• Jasco J-815 CD

Proteomics Usage Form

Please click the link below and complete the Proteomics Usage Form when using the Jasco J-815 Circular Dichroism (CD) Spectropolarimeter

Proteomics Usage Form Link

For questions, please contact Mandar Naik, PhD.