Proteins from Cosmic Ice express
In the black depths of space, on the surfaces of tiny icy dust grains, a quiet construction is underway. There, where temperatures drop to near absolute zero and harsh radiation abounds, the ordinary amino acid glycine, the simplest protein building block, links up with itself. The product is a dipeptide: a short chain of two units, already resembling a protein.
Such dust grains, coated with ice made of water and simple molecules, are true cosmic laboratories. In the experiment, a frozen film of glycine played their role. It was bombarded with protons (simulating cosmic rays) at a temperature of about minus 260 °C. And the birth of glycylglycine was recorded. No liquid water — only ice and radiation.
Glycylglycine is not just a laboratory curiosity. It is the shortest peptide bond in nature, and it already possesses some protein-like properties, such as the ability to carry copper ions in the blood.
In Carl Sagan's novel Contact, a signal from space contained blueprints for a machine, but the very idea that complex chemistry could arise in the interstellar medium resonates with this discovery.