Self Assembly of Subset of Amino Acids May Have Led to First Life

MedicalResearch.com Interview with: [caption id="attachment_70825" align="alignleft" width="150"] Dr. Frenkel-Pinter[/caption] Dr. Moran Frenkel-Pinter Ph.D. Senior Lecturer (assistant professor) Institute of Chemistry Hebrew University of Jerusalem Member of the NASA Center for the Origins of Life MedicalResearch.com: What is the background for this study? What is unique about the 20 amino acids found in living organisms? Response: One of the most fascinating mysteries in the field of origins of life concerns the driving force that led to the selection of today’s 20 universal L-alpha amino acids in biology. Out of hundreds and possibly thousands of amino acids that were present on the prebiotic Earth, only a small subset was selected for biology. An essential aspect of life's emergence involves the formation of compartments, which offer encapsulation for target molecules and provide protection from degradation in water. We postulated that primordial peptide assembly could be one of the driving forces that led to the chemical selection of alpha amino acids in life today. To test this hypothesis, we generated depsipeptides, oligomers composed of ester bonds and peptide bonds that form readily under mild drying conditions, as model prebiotic peptides. However, it was unknown whether depsipeptides form assemblies in an aqueous environment similarly to peptides and proteins. To test the hypothesis that depsipeptides with alpha backbones will form assemblies more readily than beta backbones, we synthesized depsipeptides using a matrix of alpha- and beta- hydroxy acids and alpha-, beta-, and gamma- amino acids. Our results demonstrate assembly formation in depsipeptide systems containing hydrophobic hydroxy acids and indicate that depsipeptides containing alpha hydroxy acid backbones are significantly more stable than beta analogs. Overall, our results offer an assembly-driven mode of selection for the alpha backbone in present-day biology.