Peptides are one of the smallest biomolecules and are one of life’s critical building blocks. New research shows that they could form on the surfaces of icy grains in space. This discovery lends credence to the idea that meteoroids, asteroids, or comets could have given life on Earth a kick start by crashing into the planet and delivering biological building blocks.

Peptides are short chains of amino acids, and amino acids are the building blocks of proteins. When peptides join together in a chain, they’re called polypeptides. A chain of polypeptides longer than about 50 is a protein. Sometimes peptides are called the “shorter cousins of proteins.” Proteins are larger biomolecules that play many critical biological roles, so there would be no proteins and no life without peptides. Every cell and all tissue in the body contains peptides.

According to most, Emil Fischer discovered peptides and the peptide bond in the early 20th century. He won the 1902 Nobel Prize in chemistry. Fischer thought the day would come when scientists could use peptide science to synthesize proteins. Now we live in an age of constant peptide discovery and synthesis, leading to more than 80 new therapeutics that treat a wide range of diseases. Peptides are critical, and their use is widespread. Their discovery helped usher in an age marked by a burst in our understanding of biological processes.

Their discovery in space might do the same for the understanding of the origins of life.

The sequence where amino acids and peptides come together to form organic cells. Credit: peptidesciences.com
The sequence where amino acids and peptides come together to form organic cells. Credit: peptidesciences.com

Peptides had to originate somewhere. Researchers have discovered other building blocks like amino acids in space in recent years. Astronomers found amino acids in meteorites that fell to Earth, and they’ve discovered glycine in a comet along with ammonium salts and aliphatic compounds. Now it looks like we can add peptides to the list of organic building blocks that occur naturally in space.

“It is an amazing fact that complex organic molecules exist in denser regions between the stars, in protoplanetary disks, primitive meteorites and comets.”

Thomas Henning, study co-author, MPIA.

If this new research is accurate, natural processes in space can produce basic pre-biological building blocks. This suggests that the possibility of life’s emergence could be widespread and that any fertile planet or moon has likely been seeded with these building blocks.

The research comes from scientists at the University of Jena and the Max Planck Institute for Astronomy. The paper is “A pathway to peptides in space through the condensation of atomic carbon.” The lead author is Serge Krasnokutski, and the paper is published in the journal Nature Astronomy.

“It is an amazing fact that complex organic molecules exist in denser regions between the stars, in protoplanetary disks, primitive meteorites and comets,” said Thomas Henning, co-author of the new study and director at the Max Planck Institute for Astronomy. “They can be formed by a variety of processes from processes in the gas phase, on icy grain surfaces and wet chemistry on the parent bodies of meteorites.”

In their paper, the researchers point out that complex molecules are present in the interstellar medium (ISM). Previous researchers have simulated ISM conditions in labs and produced the same complex molecules. But there’s a limit to that type of research. “Until now, however, only relatively small molecules of biological interest have been demonstrated to form experimentally under typical space conditions,” they explain.

Scientists detected glycine in Comet 67P/Churyumov-Gerasimenko' coma in 2020. In this image, Rosetta’s scientific camera OSIRIS shows the sudden onset of a well-defined jet-like feature emerging from the side of the comet’s neck, in the Anuket region. Image Credit: ESA/Rosetta/OSIRIShttps://www.mansbrand.com/ultralight-backpacking-tents-how-to-choose-one/

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