Optical activity of aromatic chromophores. I. o, m, and p‐tyrosine

Abstract The optical activity and the conformational energy of the amino acids tyrosine, o ‐tyrosine, and m ‐tyrosine have been calculated as a function of molecular conformation. A new graphic technique, rotatory strength–conformational energy maps, was developed for the presentation of these calculations. Experimental circular dichroism spectra were determined by utilization of a new experimental technique that involves complete computer control of a Cary spectropolarimeter. This permitted repetitive scanning with signal averaging over extended time periods and resulted in a greatly enhanced signal to noise ratio. On the basis of these calculations, it, was concluded that the Kirkwood “coupled oscillator” mechanism is capable of explaining the observed optical activity of the aromatic chromophores of the molecules that were investigated.