REACTIVITY OF SELECTED PRIMITIVE AMINO ACIDS INDUCED BY GAMMA IRRADIATION IN ASTROCHEMICAL CONTEXT

Amino acids in meteorites were preserved from the action of high energy sources (cosmic rays and ultraviolet protons) by their collocation, at a depth of 20 m. At the same time, the presence of radioactive elements was the cause of amino acids degradation. The radioactive elements produced a total radiation dose of 14 MGy during the life of Solar System (4.6x109 years). Beside the amino acids degradation, radiations promoted a radioracemization process that was able to reduce the L-enantiomeric excess of amino acids. Our studies are aimed to identify the radiation products formed in a solid state radiolysis using mass spectrometric techniques. Moreover, we are analyzing the radioracemization process at different irradiation conditions for proteinogenic and non proteinogenic amino acids. The amino acids show a relevant radiation and radioracemization resistance, especially the proteinaceous ones, such as leucine, valine and isoleucine. Some identified degradation pathways are significant due to their final products which can be considered precursors of more complex intermediates.