Precursors of amino acids (alanine and glycine),

have been found in space.

http://phys.org/news/2013-02-discoveries-icy-cosmic-amino-acids.html

http://arxiv.org/abs/0801.3219

It is hypothesized that the first amino acids

were encoded by only two bases. So the

first life had only 4*4 amino acids.

http://scienceblog.com/8568/scientists-crack-dna-puzzle-point-to-hot-soup-at-origin-of-life/

http://bill.srnr.arizona.edu/classes/182/EarlyEarth/BackTwoBases.htm

Maybe even the genetic code began with

only two types of amino acids. {glycine, alanine}

and {aspartic acid, valine} are suggested as

a system.

http://phys.org/news168875229.html

http://www.plosone.org/article/info:doi/10.1371/journal.pone.0005773

Regards,

Joachim

Joachim has given you the four of the oldest amino acids and I agree with him that glycine, and alanine are the most primordial. Also take a look at:

Paul G. Higgs and Ralph E. Pudritz. Astrobiology. June 2009, 9(5): 483-490. doi:10.1089/ast.2008.0280

Their study combines thermodynamics, codons, and experiments to see what might be the most primordial of the amino acids. They predict Glycine, Alanine, Aspartic acid, Glutamic acid, Valine, Serine, Isoleucine, Leucine, Proline and Threonine, in that order.

Hi Matthew, thanks for the answer. However, I am not sure if there really exists a convincing reason for argument that the most abundant prebiotic amino acids will be those first used by early life. I think that it should be more related to function than to equilibrium thermodynamic probabilities. In fact, there are non-equilibrium thermodynamic probabilities that are very different from equilibrium probabilities. For example, consider catalyst concentrations in autocatalytic reactions. I could not get a hold of the article by Higgs et al. that you cite as we don't have subscription to the journal. Could you pass it on to me if you have it or suggest another web site? Thanks a lot!

Hi Karo,

Your response is quite true. I think the list those authors provided did sample the range of typical amino acid chemistry (hydrophobic + hydrophilic), but there's a fair bit to still be done in this area.

I actually don't have a subscription to Astrobiology either, but there looks to be a copy on ArXiv:

http://arxiv.org/ftp/arxiv/papers/0904/0904.0402.pdf

I hope this helps.

Thanks for the reference Matthew!

Kenneth, do you by chance know which of the amino acids have a chemical affinity to DNA or RNA? I read in somewhere (can't remember where) that the aromatic amino acids have a chemical affinity to their DNA anti-codons. Do you have any information on this? If this is true then this might provide another criteria for saying which came first. Would you agree?