Science Gazette

The origins of life on Earth


Researchers have unearthed a fresh clue in the hunt for the beginning of life by demonstrating that peptides may develop on dust in extreme environments like space. These molecules, which are one of life’s fundamental building elements, may not have formed on Earth at all, but rather in cosmic molecular clouds.

Amino acid chains

All life as we know it is made up of the same chemical components. Peptides, for example, have a variety of activities in the body, including transporting chemicals, speeding processes, and building stabilizing scaffolds in cells. Individual amino acids are organized in a precise way to form peptides. The final qualities of a peptide are determined by its precise arrangement.

One of the concerns surrounding the genesis of life is how these flexible biomolecules came to be. The presence of amino acids, nucleobases, and different sugars in meteoroids, for example, suggests that this origin might be alien. However, in order to make a peptide from individual amino acid molecules, highly specific circumstances are needed, which were previously thought to be more common on Earth.

Water is required for the first stage, but no water is required for the second

“Water plays a significant part in the traditional approach of making peptides,” explains Dr. Serge Krasnokutski of the Max Planck Institute for Astronomy’s Laboratory Astrophysics and Cluster Physics Group at the University of Jena. Individual amino acids join to create a chain in this process. Each time this happens, one water molecule must be eliminated. “The amino acid glycine may now be made by mixing a chemical precursor termed an amino ketene with a water molecule, according to our quantum chemical calculations. Simply said, for the first reaction step, water must be introduced, and for the second, water must be withdrawn.”

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With this information, the team lead by physicist Krasnokutski has been able to establish a chemical pathway that may occur under cosmic settings without the need of water.

“Rather of taking the chemical detour that amino acids take, we wanted to see whether amino ketene molecules might be synthesized instead and combined straight to make peptides,” Krasnokutski explains the underlying premise behind the research. “We performed this under the circumstances that occur in cosmic molecular clouds, that is, on dust particles in a vacuum, where the appropriate compounds are abundant: carbon, ammonia, and carbon monoxide,” he continues.

Substrates that serve as models for dust particle surfaces were brought together with carbon, ammonia, and carbon monoxide at around one quadrillionth of normal air pressure and minus 263 degrees Celsius in an ultra-high vacuum chamber.

“Investigations revealed that the peptide polyglycine was synthesized from simple molecules under these circumstances,” Krasnokutski explains. “As a result, they are chains of the fairly simple amino acid glycine, with varying lengths. The longest specimens were made up of eleven amino acid units.”

The German team was also able to discover the probable amino ketene in this experiment. “The amino ketene molecules are exceedingly reactive, which allows the reaction to take place at such low temperatures. In a successful polymerisation, they mix with each other. Polyglycine is the end result of this process.”

The quantum mechanical tunneling effect might be involved

“However, the polymerisation of amino ketene could proceed so quickly under such circumstances surprised us,” Krasnokutski said. “This is due to the fact that an energy barrier must be crossed in order for this to occur. However, it’s possible that a quantum mechanics special effect aids us in this. A hydrogen atom swaps places in this unique chemical step. However, since it is so tiny, it could not overcome the barrier as a quantum particle and had to rely on the tunnelling effect to get across it.”

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Now that scientists know that not just amino acids, but also peptide chains, may be formed under cosmic circumstances, we may have to go beyond Earth to learn more about the origins of life.

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