Far UV Protein Circular Dichroism

Synonyms
Peptide Backbone – Amide Backbone; Protein backbone circular dichroism

Definition
Protein circular dichroism (CD) spectroscopy is usually divided into (1) far UV or backbone (meaning the amide transitions, Fig. 1) with data collected from ~190 to 250 nm and (2) near UV or aromatic with data collected from 250 to 300 nm. The practical reason for the division is that the absorbance magnitudes of the two regions for a typical protein differ by ~2 orders of magnitude. In addition, the far UV CD spectrum of a protein contains information about the asymmetric features of the backbone of proteins whereas the near UV depends on the orientations and environments of the side chains. The challenge is to extract the structural information. The most common reason for collecting protein CD data is to assign secondary structure content by expressing the spectra as a combination of standard spectra which are then deconvoluted to give the percentages of a limited number of well-defined...