Aim:

To estimate the secondary structural components of a protein from its far-UV circular dichroism spectrum using CDPro software suite

Introduction:

As discussed in the previous lecture, peptide bond constitutes the major protein chromophore in the far-UV region. The absorbance in the far UV region is the manifestation of n → π* transitions around 220 nm and π → π* transitions below 210 nm. The orientation of the peptide bonds in the secondary structural elements greatly influences their CD signals. Let us have a look at the characteristic spectral features of the major secondary structural components present in proteins (Figure 10.1).

Figure 10.1 Far UV CD spectra of α-helix (red), β-sheet (blue), and unordered conformations (green)