“One of the long-standing questions in origins-of-life research centers on how the proteinaceous side chains and the protein backbone were selected during the earliest phases of evolution. Here we have studied
oligomerization reactions of a group of positively charged amino acids, both proteinaceous and nonproteinaceous. Amino acids spontaneously oligomerized without the use of enzymes or activating agents, under mild, hydroxy acid-catalyzed, dry-down conditions. We observed that the
proteinaceous amino acids oligomerized more extensively and with greater preference for reactivity through their α-amine compared with nonproteinaceous amino acids, forming predominantly linear, protein-like backbone topologies. These findings provide a purely chemical basis for selection of the positively charged amino acids found in today’s proteins.”— et al. “Selective incorporation of proteinaceous over nonproteinaceous cationic amino acids in model prebiotic oligomerization reactions.” PNAS.
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