Amino acids radiation decomposition

It is still unclear what kind of radiation sources can lead to asymmetric reactions. Jeremy Bailey from the Anglo-Australian Observatory in Epping, Australia, investigated which astronomical objects could be considered radiation sources (Bailey et al., 1998 Bailey, 2001). It was possible in laboratory experiments to generate a small enantiomeric excess of some amino acids by using circularly polarized UV light (Norden, 1977). This asymmetric photolysis involves photochemical decomposition of both d- and L- enantiomers, but at different rates, so the more stable form tends to survive. This process must be subject to autocatalytic multiplication. 

Figure 3 is the same plot for alanine. The curves are all initially linear and the G values were calculated from this initial linear portion. Low deviations on the ammonia curves at the highest absorbed dose may reflect high decomposition of original amino acid. Amino acids with higher specific activities were used to determine G(C02) at lower absorbed doses. These values are significantly lower as shown in Figure 4. The problem of impurity introduced by the radiation decomposition of the original material and its effect on measured G values confronts all workers in this area. For consistency and since these values have a much more reliable analytical basis, the high dose values will be used throughout. The results of interest are the relative G values in any case since absolute values are acknowledged to depend on dose.

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