Peptides key to the origin of life?

Peptides: essential elements of life

Peptides are organic compounds that are essential for life and play a central role in many biological processes. Part of their importance lies in their ability to function as enzymes, molecules that catalyze a wide range of chemical reactions in living cells.

Like enzymes, peptides facilitate and accelerate specific chemical reactions without being changed or consumed. This catalytic ability of peptides is essential for metabolism, cell growth, tissue repair and many other vital biological processes.

In addition to their role as enzymes, peptides are involved in the regulation of various biological processes, such as cell signaling, cell-cell communication and immune defense.

For example, some hormones and neurotransmitters are peptides that act as chemical messengers in the body, transmitting signals between cells and tissues to regulate various physiological functions.

These compounds also play an important role in the structure and function of proteins, which are essential for cell structure, nutrient transport, cellular communication and many other biological processes.

As protein precursors, peptides participate in the synthesis of polypeptide chains that then fold to form functional three-dimensional structures.

Peptides in space?

However, recent studies suggest that simple peptides can form on cosmic dust grains found in interstellar environments. However, it was previously thought that this would not be possible if the molecular ice covering the dust particles contained water ice, which is usually the case.

Recently, a team of researchers led by Dr. Serge Krasnokotzky, from the University of Jena, in collaboration with the University of Poitiers, that the presence of water molecules ultimately does not pose a significant obstacle to the formation of peptides on these dust grains. .

In detail, as part of their work, the scientists have simulated conditions similar to those in space in a vacuum chamber.

To simulate the environments in so-called molecular clouds, they introduced substances such as ammonia, atomic carbon and carbon monoxide. These chemical elements are present in these clouds and provide the ingredients needed to form simple peptides.

By simulating these conditions, the researchers were able to study how these peptides form naturally in space, which could have important implications for our understanding of the origins of life on Earth and beyond.

Challenges and discoveries: the role of water

According to the analyses, the starting materials introduced in the experiment first produced compounds called aminoketines. These aminoketins are essentially chemical precursors to amino acids, the building blocks of proteins. When these aminoketines are then linked together, they form chains called polypeptides. Polypeptides are larger molecules composed of multiple amino acids arranged in a specific order.

It was previously thought that individual aminoketines combine directly to form peptides, chemical compounds essential for life. However, recent research shows that aminoketines are first converted into amino acids, which in turn combine to form polypeptides and then peptides, before ultimately yielding functional proteins. This process represents a crucial step in the synthesis of molecules necessary for life in cosmic environments, simulated in the laboratory.

However, for this step, as mentioned above, it was thought that the presence of water could hinder the process. However, we know that most interstellar dust grains are covered in hydrous molecular ice. Therefore, the assumption until now was that peptides do form in space, but that this only happens to a limited extent.

However, the most precise spectroscopic analyzes now possible at the University of Poitiers have shown that the water in molecular ice ultimately slows down the formation of peptides by only 50%. In other words, it can still be formed. Considering the time scale on which astronomical processes occur, this delay seems quite insignificant.

Cosmic implications: towards a new perspective on the origin of life

By reproducing conditions from space, scientists have successfully synthesized basic chemical compounds, such as amino acid precursors, in a vacuum chamber. These compounds are essential for the formation of proteins, which are essential for life as we know it.

This experiment then suggests that the necessary ingredients for life are present in space, in environments such as molecular clouds. This opens the door to the intriguing possibility that the first biomolecules, or at least their predecessors, could have formed elsewhere in the universe and spread through space, perhaps carried by meteorites or other celestial bodies.

While this idea may seem speculative, it obviously raises fascinating questions about the possibility that life on Earth could have a cosmic origin. If this were the case, it would profoundly change our understanding of life and its ubiquity in the universe.

source: Progress of science