Nonenzymatic, Prebiotic Aminoacylation Couples Chirality of RNA and Protein.

Life, as we know, depends on the homochirality of nucleic acids and proteins. However, there is no widely accepted explanation for why life uses only d-sugars for nucleic acids and l-amino acids for proteins. Here, we demonstrate a prebiotically plausible method of nonenzymatic aminoacylation in a water ice-eutectic phase. These reactions produce high yields of aminoacyl-tRNAs, which are active in translation. Surprisingly, we discovered these nonenzymatic aminoacylation conditions were stereoselective, favoring coupling of amino acids and RNA of "opposite" l- and d- configurations. d-RNA shows greater aminoacylation yields for l over d-amino acids. The opposite was true for l-RNA, which had greater yields with d over l-amino acids. Nucleic acid backbone chirality influencing the stereoselectivity of aminoacylation represents a missing link between the amino acid and nucleic acid configurations. This phenomenon provides insight into the chirality of the RNA world and helps explain the "opposite" stereochemistry of modern biomolecules.