Scientists have proposed that life on Earth first appeared in the waters for many years. But the chemistry remained a mystery. Raw amino acids, which the early Earth received daily from meteorites, can react and latch together to create peptides, which are the basis for proteins and, eventually, life. Strangely, the procedure calls for the loss of a water molecule, which seems exceedingly improbable in a moist, aquatic, or oceanic environment. It required water for life to develop. However, it also needed room away from the sea.
Scientists have been baffled by peptide-forming events in water for many years, but Purdue University chemists have now solved the mystery.
Graham Cooks, the Henry Bohn Hass Distinguished Professor of Analytical Chemistry in Purdue’s College of Science, said, “This is essentially the chemistry behind the origin of life. This is the first demonstration that primordial molecules, simple amino acids, spontaneously form peptides, the building blocks of life, in droplets of pure water. This is a dramatic discovery.”
According to scientists, this water-based chemistry could also lead to the faster development of drugs to treat humanity’s most debilitating diseases.
Cooks said, “Water isn’t wet everywhere. On the margins, where the water droplet meets the atmosphere, incredibly rapid reactions can take place, transforming abiotic amino acids into the building blocks of life. Places where sea spray flies into the air and waves pound the land, or freshwater burbles down a slope were fertile landscapes for life’s potential evolution.”
“The chemists have spent more than 10 years using mass spectrometers to study chemical reactions in water droplets. The rates of reactions in droplets are anywhere from a hundred to a million times faster than the same chemicals reacting in bulk solution.”
Catalysts are not required for these reactions because of their high speeds, which accelerate them and enable the emergence of life in the case of early Earth chemistry. Decades of scientific investigation have been focused on figuring out how this system works. The secret of how life arose on Earth can help scientists understand why it happened and inform the search for life on other planets or moons.
Scientists’ understanding of chemical synthesis has been completely transformed by our growing understanding of how amino acids assemble themselves into proteins and living forms. The same chemistry may help synthetic chemists identify and create new medications and treatments for diseases by accelerating key reactions.
Cooks said, “If you walk through an academic campus at night, the buildings with the lights on are where synthetic chemists work. Their experiments are so slow that they run for days or weeks at a time. This isn’t necessary, and using droplet chemistry, we have built an apparatus, which is being used at Purdue now, to speed up the synthesis of novel chemicals and potential new drugs.”
- Dylan T. Holden, Nicolas M Morato et al. Aqueous microdroplets enable abiotic synthesis and chain extension of unique peptide isomers from free amino acids. PNAS. DOI: 10.1073/pnas.221264211