Laboratory simulation of UV irradiation from the Sun on amino acids. I: irradiation of tyrosine

The effects of ultraviolet (UV) irradiation on water solutions of tyrosine (HO-C(6)H(4)-CH(2)-CHNH(2)-COOH) have been investigated using a Xe lamp in the region 200-800 nm. This is a step in laboratory simulation towards reproducing the action of the Solar radiation on the building blocks of life, specifically alpha-amino acids, in the primitive Earth anoxic conditions. Results are presented showing the photostability of tyrosine against different UV doses. Degradation products partly maintain life building capability and partly do not. A tendency towards structure complexification was observed. The analysis of the irradiated tyrosine solutions was conducted using various spectroscopic and analytic techniques. The laboratory results are discussed in the light of a primordial life-emerging scenario.