Optical activity of crystalline glutamic acids

As the first study on gyro-optical properties of amino acids, temperature dependences of the gyration tensor components of L- and D-glutamic acids were measured by using the HAUP (high-accuracy universal polarimeter). It was confirmed that the corresponding tensor components of the two enantiomers are the same in magnitude but opposite in sign. It is proposed that r = (rho(C)(0) - rho(S)(0))/rho(C)(0) be defined as the 'chirality index', where rho(C)(0) and rho(S)(0) designate rotatory powers per molecule in a crystal and in a dissolved state in liquid, respectively. It represents a measure of structural contribution of optical activity (OA) in a crystal. This value is 0.992 in glutamic acids.