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  • 1 Fachhochschule Aachen, Abteilung Jülich, 517 Jülich Ginsterweg, (FRG)
  • | 2 Biological Research Center Institute of Biophysics, Odesszai Körut 62, 6701 Szeged, (Hungary)
  • | 3 Kernforschungsanlage Jülich Institut für Chemie (ICH), Postfach 365, 517 Jülich, (FRG)
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If an optically active organic substance is labelled in the chirality center with another isotopic species (such as15N for14N) a pronounced variation of rotatory power is predicted. We tried to varify this idea experimentally on L-α-alanine and found an isotope effect of ORD (optical rotatory dispersion). The magnitude of the rotation is mainly dependent on the pH of the solvent. The ratio of the optical activity alanine-14N/alanine-15N is about 1.02. The molecular rotations show a consistently lower ratio but it can be seen that the isotope effect is not only a mass effect.