Circular Dichroism

Applied Photophysics Chirascan VX

Circular dichroism (CD) is a spectroscopic technique used to characterise chiral materials by measuring the differential absorption of left-handed and right-handed circularly polarised light. A monochromator produces horizontal linearly polarised light and a photoelastic modulator converts it to circularly polarised light, alternating between left- and right-handed. Notably it can provide structural information on biomolecules, such as secondary and tertiary structure of proteins, through its sensitivity to their optically active chromophores – amino acids residues and peptide bonds. By extension CD can also provide conformational analysis of peptides and peptidomimetics.


Chirascan VX features:

  • Wavelength range from 160 nm up to 950 nm. Typically, owing to variation of CD amplitude with wavelength, narrower ranges are used such as far-UV (ca. 160-250nm) for protein secondary structure and near-UV (250-350nm) for tertiary structure.
  • Peltier temperature controller to maintain sample/sample chamber at constant temperature.
  • Can also perform continuous or stepped temperature ramps from 20 °C up to 100°C, with single wavelength or multi-wavelength scans to determine thermodynamic and kinetic properties.
  • Range of measurement cells – 10 mm stoppered cuvette and 0.5 mm stoppered cuvette with 10 mm adaptor are currently available. Cuvettes down to 0.01 mm path length can be fitted – an adaptor for thinner cuvettes is already available but the cuvettes themselves must be ordered.