CD 

Linearly Polarized Light – direction of electric vector is constant but magnitude

          is modulated.

Circularly Polarized Light – magnitude is constant, but direction is modulated.

          Circularly polarized light may be either “right-handed” or “left-handed.”

CD (Circular Dichroism) – difference in absorption or left and right circularly

          polarized light.   (e_L  ¹  e_R)  Very small effects, far UV (170 – 300 nm)

     D (l) = A_L (l)  - A_R(l)  =  [e_L(l)  -  e_R(l)] lc  =  De lc  

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   Figures / Illustrations of Data:

   1. A) CD and ORD poly-L-Lys in a-helical, b-sheet, and random coil.

        B) Experimentally observed CD for helical protein myoglobin.

   2. Expanded wavelength range for CD of “pure” secondary structures.

   3. CD sprectrum of representative protein structures.

   4. Use of CD spectra to estimate secondary structure of proteins.

                   Fraction helix content  =   (theta)q₂₀₇  / -57000 

                   Better way: Singular Value Decomposition Analysis

                   (Find the best matrix that can be used to generate the best fit for

                                 converting CD sprectra into secondary structure.)

    5. Use of CD to monitor folding or denaturation of proteins

    6. CD sprecta of DNA to monitor folding or denaturation of DNA

       CD spectra of DNA to estimate secondary structure of nucleic acids