When Earth was a lifeless planet about 4 billion years ago, chemical components came together in tiny molecular chains that would later evolve into proteins, crucial life building blocks. A new study has shown how fortuitously some early predecessors of protein might have fallen into line. In the laboratory, under conditions mimicking those on pre-life Earth, a small selection of amino acids linked up spontaneously into neat segments in a way that surprised researchers. They had given these amino acids found in proteins today some stiff competition by adding amino acids not found in proteins, thinking these non-protein, or non-biological, amino acids would probably not allow predominantly biological segments to come together. The non-biological amino acids had the potential to chemically react equally well or better than the biological ones and frequently become part of the tiny chains, perhaps serving as an in-between step in the greater evolution toward proteins. The experiment dashed those expectations -- but to the researchers' delight. The reactions resulted mostly in strings that were closer to today's actual proteins and less in chains that included non-biological amino acids.
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