Peptides are among the smallest biological molecules and one of the key building blocks of life. New research shows they can form on the surfaces of ice particles in space. The discovery lends credence to the idea that meteors, asteroids or comets could kick-start life on Earth by hitting the planet and providing biological building blocks.
Peptides are short chains of amino acids, the building blocks of proteins. When peptides are linked together to form a chain, they are called polypeptides. Polypeptide chains longer than about 50 are proteins. Sometimes peptides are called "short cousins ??of proteins". Proteins are larger biomolecules that play many important biological roles, so without peptides there would be no proteins and therefore no life. Every cell and all tissues in the body contain peptides.
Most people agree that Emil Fischer discovered peptides and peptide bonds in the early 20th century. He won the 1902 Nobel Prize in Chemistry. Fisher believes that one day scientists will be able to use peptide science to synthesize proteins. We now live in an era of continuous discovery and synthesis of peptides, resulting in more than 80 new treatments for various diseases. Peptides are key and their uses are vast. Their discovery helped usher in an era of dramatic advances in our understanding of biological processes.
And the discovery of peptides in space may have the same implications for understanding the origins of life.
Peptides must have originated somewhere. In recent years, researchers have discovered other building blocks, such as amino acids, in space. Astronomers have discovered amino acids in meteorites that have fallen to Earth, and they have found glycine in comets, along with ammonium salts and aliphatic compounds. New research suggests we can add peptides to the list of organic building blocks found naturally in space.
If the new research is accurate, natural processes in space could have produced basic prebiotic building blocks. This suggests that the possibility of life may have been widespread, and that any fertile planet or moon may have been seeded with these building blocks.
Scientists from the University of Jena and the Max Planck Institute for Astronomy in Germany published a paper in the journal Nature Astronomy on February 10, titled "Through the Condensation of Atomic Carbon in Space "Pathway to form peptides in", the main author of the paper is Serge Krasnokutski.
Thomas Henning, co-author of the new study and director of the Max Planck Institute for Astronomy, said: "It is surprising that complex organic molecules exist within stars. They can form in denser regions between interstellar space, protoplanetary disks, primitive meteorites, and comets through various processes in the gaseous phase, on icy particle surfaces, and in the wet chemistry of the meteorite parent body."
The researchers note in their paper that complex molecules exist in the interstellar medium. Previous researchers simulated interstellar medium conditions in the laboratory and produced the same complex molecules. But this type of research has limits. So far, only relatively small biologically significant molecules have been shown to form in the laboratory under typical conditions in space.
]The study by German scientists focuses on the icy surfaces of dust particles - specifically carbon or silicate atoms - that exist in giant molecular clouds. Most of the material in these giant molecular clouds is hydrogen and helium, but half of the remaining mass is these carbon and silicate atoms. Carbon and silicate atoms clump together to form aggregates less than a millionth of a meter in diameter. Their location within giant molecular clouds is crucial because stars, as well as planets, are formed from materials in giant molecular clouds. This is the beginning of potential links between peptides and life on Earth or elsewhere.
This work differs from previous efforts to generate small molecules of biological importance. Peptides are chains of amino acids, so they are larger than previously produced substances such as formaldehyde. The new study focuses on ice layers of carbon and silicate atoms. These layers provide a natural laboratory where materials adhere to the ice and are in close contact with each other. This proximity allows chemical reactions to form more complex molecules.
The authors of the paper write: “We experimentally demonstrate that the condensation of carbon atoms on the surface of cold solid particles (cosmic dust) leads to the formation of isomeric polyglycine monomers (aminoketene molecules).
After the aminoketene molecules meet, they polymerize to produce peptides of different lengths. ”
The discovery was largely due to the scientific efforts of lead author Krasnokutsky, who developed and patented a method for producing cold carbon atoms , a method that can replicate space conditions in the laboratory, is now used by laboratories around the world
In 2020, Krasnokutsky published results showing that the simplest amino acid— —Glycine can be formed on the surface of dust particles with the help of cold carbon atoms. He demonstrated that these chemical reactions do not require ultraviolet photons as an energy source.
"Even at the lowest temperatures," Krasnokutsky said. , individual carbon atoms are also surprisingly reactive. They act as 'molecular glue', linking molecules together and converting inorganic substances into organic substances. ”
The next question to consider is: Can a simple amino acid like glycine form longer peptide or protein chains in space?
Find out the answer The only way to do this was to design and conduct the right experiments. The team needed to replicate the key conditions for cold carbon atoms in space, using a method previously developed by the Astrophysics Group at the MPIA Laboratory at the University of Jena. Creating a vacuum like that found in molecular clouds in the interstellar medium
Inside the ultrahigh vacuum chamber, the researchers simulated the surfaces of icy dust particles and deposited atoms and molecules on their surfaces. Aminoketenes formed on the cold surface. Aminoketenes are precursors to glycine, the simplest amino acid. They also found evidence of peptide ribbons, which bind amino acids in short chains of peptides as well as longer proteins. The chemical bonds that hold them together in the chain.
These peptide bands only appeared when the team heated their samples to temperatures higher than those found inside the molecular clouds, so they could appear as new stars form. Occurs naturally, or when dust grains are deposited on the surface of a planet in the habitable zone of a star, the researchers said: "The combination of low-temperature chemical reactions that form aminoketenes and the warming process that allows aminoketene molecules to combine to form peptides can occur in the atmosphere. Peptides produced on interstellar dust particles. ”
The team discovered a new pathway to form peptides. And it requires less energy than other pathways, meaning it can occur naturally in the cold of outer space. Additionally, it requires carbon atoms, carbon monoxide and ammonia, which are the most abundant molecular species in the interstellar medium
Carbon is at the center of it all, as it is in all life. “A single carbon atom gives rise to a rich diversity of chemistry. reaction. Even under the conditions found in outer space, this chemistry is closer than previously thought to producing the materials needed for the emergence of life," Krasnokutsky said.
Scientists have discovered that the ingredients for life Much more widespread than they thought. Through this study, we found that some of these components can combine into biological building blocks in an unlikely place, even in the frozen vacuum within the interstellar medium's molecular clouds when conditions warm. , the complexity of these building blocks increases.
These results strengthen the idea of ??molecular panspermia, a theory that suggests that although life is rare, these building blocks may have spread. to every planet and moon, although life is unlikely to exist on most worlds. If this is true, life may have arisen on numerous moons and planets throughout the universe.
But research suggests. , many worlds may experience periods of habitability, but never remain habitable for long periods of time, meaning Earth remains rare and perhaps even unique.