Water droplets hold the secret ingredient for building life

Purdue University chemists have discovered a mechanism by which peptide-forming reactions can take place in water — something that has puzzled scientists for decades.

“This is essentially the chemistry behind the origin of life,” said Graham Cooks, the Henry Bohn Hass Distinguished Professor of Analytical Chemistry in Purdue’s College of Science. “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.”

This water-based chemistry, which leads to proteins and thus life on Earth, could also accelerate the development of drugs to treat humanity’s most debilitating diseases. The team’s discovery was published in the journal Proceedings of the National Academy of Sciences.

For decades, scientists have theorized that life on Earth began in the oceans. The chemistry, however, remained a mystery. Crude amino acids — something delivered daily to early Earth by meteorites — can react and snap together to form peptides, the building blocks of proteins and ultimately life. Curiously, the process requires the loss of a water molecule, which seems highly unlikely in a wet, aqueous or oceanic environment. To form life, it needed water. But it also needed space away from the water.

Cooks, an expert in mass spectrometry and early Earth chemistry, and his team have discovered the answer to the riddle: “Water isn’t wet everywhere.” At the edge, where the water drop meets the atmosphere, incredibly fast reactions can take place, converting abiotic amino acids into the building blocks of life. Places where sea spray flies into the air and waves pound the land, or where fresh water lapping from a slope, were fertile landscapes for the potential evolution of life.

The chemists have worked with mass spectrometers for more than 10 years to study chemical reactions in droplets containing water.

“The rates of reactions in droplets are somewhere between a hundred and a million times faster than the same chemicals reacting in bulk solution,” Cooks said.

The rates of these reactions make catalysts obsolete, speed up the reactions and, in the case of early Earth chemistry, allow the evolution of life. Understanding how this process works has been the goal of decades of scientific research. The secret of how life originated on Earth could help scientists understand why it happened and could inform the search for life on other planets or even moons.

Understanding how amino acids built themselves into proteins and ultimately life forms is revolutionizing scientists’ understanding of chemical synthesis. That same chemistry could now help synthetic chemists speed up the reactions critical to discovering and developing new drugs and therapeutic treatments for disease.

“If you walk through an academic campus at night, the buildings with the lights on are where synthetic chemists are at work,” Cooks said. “Their experiments are so slow they run for days or weeks at a time. This isn’t necessary, and using droplet chemistry we built a device, which is now being used at Purdue, to accelerate the synthesis of new chemicals and identify potential new drugs.” .”