Journal of Radioanalytical and Nuclear Chemistry

, Volume 295, Issue 2, pp 1235–1243 | Cite as

Solid state radiolysis of non-proteinaceous amino acids in vacuum: astrochemical implications

  • Franco Cataldo
  • Giancarlo Angelini
  • Yaser Hafez
  • Susana Iglesias-Groth


The analysis of the amino acids present in Murchison meteorite and in other carbonaceous chondrites has revealed the presence of 66 different amino acids. Only eight of these 66 amino acids are proteinaceous amino acids used by the present terrestrial biochemistry in protein synthesis, the other 58 amino acids are somewhat “rare” or unusual or even “unknown” for the current terrestrial biochemistry. For this reason in the present work a series of “uncommon” non-proteinaceous amino acids, namely, l-2-aminobutyric acid, R(−)-2-aminobutyric acid, 2-aminoisobutyric acid (or α-aminoisobutyric acid), l-norleucine, l-norvaline, l-β-leucine, l-β-homoalanine, l-β-homoglutamic acid, S(−)-α-methylvaline and dl-3-aminoisobutyric acid were radiolyzed in vacuum at 3.2 MGy a dose equivalent to that emitted in 1.05 × 109 years from the radionuclide decay in the bulk of asteroids or comets. The residual amount of each amino acid under study remained after radiolysis was determined by differential scanning calorimetry in comparison to pristine samples. For optically active amino acids, the residual amount of each amino acid remained after radiolysis was also determined by optical rotatory dispersion spectroscopy and by polarimetry. With these analytical techniques it was possible to measure also the degree of radioracemization undergone by each amino acid after radiolysis. It was found that the non-proteinaceous amino acids in general do not show a higher radiation and radioracemization resistance in comparison to the common 20 proteinaceous amino acids studied previously. The unique exception is represented by α-aminoisobutyric acid which shows an extraordinary resistance to radiolysis since 96.6 % is recovered unchanged after 3.2 MGy. Curiously α-aminoisobutyric acid is the most abundant amino acid found in carbonaceous chondrites. In Murchison meteorite α-aminoisobutyric acid represents more than 20 % of the total 66 amino acids found in this meteorite.


Amino acids Radiolysis DSC ORD Racemization Astrochemistry Asteroids Meteorites 



The present research work has been supported by grant AYA2007-64748 Expte. NG-014-10 of the Spanish Ministerio de Ciencia e Innovacion. The National Center for Astronomy, KACST, Saudi Arabia is also gratefully acknowledged for a partial support of the present work.


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Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2012

Authors and Affiliations

  • Franco Cataldo
    • 1
    • 2
  • Giancarlo Angelini
    • 3
  • Yaser Hafez
    • 4
  • Susana Iglesias-Groth
    • 5
  1. 1.Istituto Nazionale di Astrofisica, Osservatorio Astrofisica di CataniaCataniaItaly
  2. 2.Lupi Chemical ResearchRomeItaly
  3. 3.Istituto di Metodologie Chimiche, CNRMonterotondo Stazione, RomeItaly
  4. 4.National Center for Astronomy, KACSTRiyadhSaudi Arabia
  5. 5.Instituto de Astrofisica de CanariasLa LagunaSpain

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