Scientists discover the “chemistry behind the origin of life”

Chemists discover a mechanism whereby peptide-forming reactions occur in water, leading to proteins and thus life on Earth. It could also lead to faster development of drugs to treat humanity’s most debilitating diseases.

Water droplets contain the secret ingredient for building life

Chemists discover the key to Earth’s first chemistry, which could open pathways to accelerate chemical synthesis for drug discovery.

Purdue University chemists have discovered a mechanism by which peptide-forming reactions occur in water, which has baffled scientists for decades.

“This is essentially the chemistry behind the origin of life,” Graham Cooks said. He is the Henry Bohn Hass Distinguished Professor of Analytical Chemistry at Purdue’s College of Science. “This is the first demonstration that primordial molecules are simple

Amino acids are a set of organic compounds used to build proteins. There are about 500 naturally occurring known amino acids, though only 20 appear in the genetic code. Proteins consist of one or more chains of amino acids called polypeptides. The sequence of the amino acid chain causes the polypeptide to fold into a shape that is biologically active. The amino acid sequences of proteins are encoded in the genes. Nine proteinogenic amino acids are called “essential” for humans because they cannot be produced from other compounds by the human body and so must be taken in as food.

” data-gt-translate-attributes=”[{” attribute=””>amino acids, spontaneously form peptides, the building blocks of life, in droplets of pure water. This is a dramatic discovery ”.

“This is essentially the chemistry behind the origin of life.” – Graham Cooks

This water-based chemistry, which leads to proteins and ultimately life on Earth, could also lead to faster development of drugs to treat humanity’s most debilitating diseases. The team’s discovery was published today (October 3, 2022) in the magazine Proceedings of the National Academy of Sciences.

Scientists have theorized for decades that life on Earth began in the oceans. However, the chemistry behind this remained an enigma. Raw amino acids – something meteorites deliver to early Earth on a daily basis – can react and bind together to form peptides. These are the building blocks of protein and, ultimately, of life. Oddly, the process requires the loss of a water molecule, which seems extremely unlikely in a humid, aqueous or oceanic environment. For life to form, it needed water. However, it also needed space away from the water.

Cooks, an expert in mass spectrometry and early Earth chemistry, and his research team have uncovered the answer to the puzzle: “Water isn’t wet everywhere.” At the edge, where the drop of water meets the atmosphere, extremely rapid reactions can occur, turning abiotic amino acids into the building blocks of life. Thus, fertile landscapes for the potential evolution of life were in places where sea spray flies into the air and waves hit the land, or where fresh water gurgles down a slope.

“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 ”. – Graham Cooks

Chemists have used mass spectrometers to examine chemical reactions in water-containing droplets for more than 10 years.

“Reaction rates in droplets are one hundred to one million times faster than the same chemicals reacting in bulk solution,” Cooks said.

The rapid rates of these reactions render catalysts superfluous, accelerating reactions and, in the case of Earth’s first chemistry, making life evolution possible. Decades of scientific research have focused on understanding how this mechanism works. The secret of how life emerged on Earth can help scientists better understand why it happened and guide their search for life on other planets, or even moons.

Understanding how amino acids formed themselves in proteins and ultimately in life forms revolutionizes scientists’ understanding of chemical synthesis. That same chemistry could potentially help synthetic chemists identify and create new drugs and therapeutic treatments for disease by accelerating key processes.

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

Reference: “Aqueous micro-droplets enable abiotic synthesis and chain extension of unique peptide isomers from free amino acids” by Dylan T. Holden, Nicolás M. Morato and R. Graham Cooks, October 3, 2022, Proceedings of the National Academy of Sciences.
DOI: 10.1073 / pnas.2212642119

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