Abstract: | We present here a brief analysis of ultraviolet isotropic absorption and related circular dichroism of the n–π* and π–π* transitions for the peptide (amide) chromophore in the 185–240 mμ region. Investigations by ultraviolet absorption and circular dichroism techniques on natural amino acids with aromatic chromophores in their side chains are also reported. By taking into account both the peptide and aromatic transitions we discuss the conformational studies of proteins with aromatic side-chain effects. Our attention is largely focused on the optical rotatory dispersion and circular dichroism spectra of these proteins in the near ultraviolet region, where characteristic aromatic side-chain bands occur. The 185–240 mμ region is also discussed when evidence exists of overlapping Cotton effects of aromatic and peptide groups. |