Practice question

Circular dichroism spectra are divided by wavelength region. Far-ultraviolet below 240 nanometers originates from backbone amide transitions reporting secondary structure. Near-ultraviolet between 260 and 320 nanometers arises when aromatic side chains of tryptophan, tyrosine, phenylalanine and disulfide bonds are immobilized within chiral protein tertiary scaffold, gaining induced optical activity. Free amino acids in solution show minimal near-ultraviolet CD. Fine structure and intensity in this region therefore reveal tertiary packing and environmental asymmetry, while changes reflect unfolding, mutation or ligand binding perturbations.