Which amino acids should be used in prebiotic chemistry studies?

The adsorption of amino acids on minerals and their condensation under conditions that resemble those of prebiotic earth is a well studied subject. However, which amino acids should be used in these experiments is still an open question. The main goal of this review is to attempt to answer this question. There were two sources of amino acids for the prebiotic earth: (1) exogenous -- meaning that the amino acids were synthesized outside the earth and delivered to our planet by interplanetary dust particles (IDPs), meteorites, comets, etc. and (2) endogenous -- meaning that they were synthesized on earth in atmospheric mixtures, hydrothermal vents, etc. For prebiotic chemistry studies, the use of a mixture of amino acids from both endogenous and exogenous sources is suggested. The exogenous contribution of amino acids to this mixture is very different from the average composition of proteins, and contains several non-protein amino acids. On the other hand, the mixture of amino acids from endogenous sources is seems to more closely resemble the amino acid composition of terrestrial proteins.