Solving the mystery of how catalytic organic polymers first appeared on prebiotic Earth will unlock important insights into the origins of life.

Researchers at Tohoku University have recently discovered a possible environment in which the formation of catalytic organic polymers can occur. To make this discovery, they evaporated boric acid-containing amino acid solutions and found that boric acid promoted polypeptide formation in both neutral and acidic environments. The longest peptides formed in the experiments were 39 monomer-long glycine polypeptides under neutral conditions.

Previous studies have shown that the highly alkaline environment by evaporation serves as a site for ancient protein synthesis, forming up to 20 monomeric glycine peptides. Neutral conditions were believed to be worst for peptide synthesis.

An ancient boron-rich coastal region may have catalyzed the polymerization of amino acids. Author: Yoshihiro Furukawa

Boron-containing minerals have been found in abundance in some of the oldest sedimentary rocks found on Earth, dating back 3.8 billion years. These findings suggest that boric acid-rich coastal regions of ancient small continents and islands spontaneously assemble amino acids to form polypeptides and protoproteins.

“The formation of polypeptides in neutral environments is important in the chemical evolution of the origin of life,” says lead author Yoshihiro Furukawa, an associate professor at Tohoku University.

While RNAs are highly stable under neutral conditions, they are extremely unstable under alkaline conditions. Boron is known to assist in many stages of abiotic synthesis of ribonucleotides.

“Boron-enriched neutral evaporite environments serve as an ideal site for formation and interaction between the two main polymers on the prebiotic Earth,” says Furukawa.

This research group is currently investigating which amino acids are incorporated into protopeptides in this medium. Source