1. CIRCULAR DICHROISM SPECTROSCOPY structural analysis of nmol samples of macromolecules Prof. Eric Wickstrom

2. Circular Dichroism is the difference in absorption between left and right hand circularly polarised light in chiral molecules. A chiral molecule is one with a low degree of symmetry which can exist in two mirror image isomers. Illustrated above is an example of circular dichroism in glucose, a simple sugar.

3. orthogonal electronic (E) and magnetic (B) components of linearly polarized light EE BB

4. electronic field of linearly polarized light (left) right-handed circularly polarized light (right)

5. Ellipticity, 

6.  Prism Polarizer

7. The most commonly used units are mean residue ellipticity,  (degree·cm 2 /dmol), and the difference in molar extinction coefficients called the molar circular dichroism, ε L -ε R =Δε (liter/mol·cm). The molar ellipticity [  ] is related to the difference in extinction coefficients by [  ] = 3298 Δε.

8. Typical Initial Concentrations Protein Concentration: 0.5 mg/ml Cell Path Length: 0.5 mm Stabilizers (Metal ions, etc.): minimum Buffer Concentration : 5 mM or as low as possible while maintaining protein stability Contaminants: Unfolded protein, peptides, particulate matter (scattering particles)