Using special equipment to make an analogue of interstellar ice an international team of scientists performed some chemical reactions typical for deep space to get the molecules of chelating agents — the substances that once allowed metal ions getting into the first primitive protocells to ensure normal life activity for the cells and to accelerate the process of copying a strand of ribonucleic acid (RNA), one of the tree key macromolecules contained in cells of any living organism. The theoretical part of research was conducted in the Samara University, and the experimental one — in the University of Hawaii (USA).
“The scientific merit of our research is that for the first time in the world organic chelating agents were obtained with the analogues of interstellar ices. It’s another step to unveiling the secret of terrestrial life emergence. According to the scientists, chelating agents used to be critical for existence and development of the first biological protocells. These substances enable metal ion transfer through the cell membrane so that they could participate in catalyzing RNA replication, i.e. in the process of ancient protocells’ replication and division,” Ivan Antonov, Associate Professor of the Department of Physics in the Samara University and one of authors of the research, shared.
As the scientist noted, the issue of chemical prerequisites for emergence and development of life Earthside is key for astrochemistry and astrobiology. Astrophysicists suppose that the early lifeforms might have contained biomolecules in the form of RNA and amino acids. A key role in RNA stabilization and copying (replication) is given to metal ions such as magnesium, for example. Nowadays, cells use special proteins to transport ions through their membranes, but these proteins are too large and complex, so they could hardly existed in the prehistoric times of the first protocells.
“The transfer of ions through the cell membrane is essential for all the contemporary life forms; it’s a foundational mechanism, but, since the ancient cells were able to do it without complex proteins used by today’s cells, this issue remains unclear. We suppose that ions could be transferred with the chelating agents that had once emerged in space in the interstellar ice and then came to Earth with the meteorites.
In our research, we showed how chelating agents can form quite quickly in the analogues of interstellar ices using a certain set of chemical reactions,” Ivan Antonov said.
Chelating agents can be called molecular ‘space suits’ of sort — it is as though the molecules of these substances enveloped metal ions solidly, embraced them firmly, so that the ions in these ‘suits’ could easily penetrate through the cell membrane to perform their tasks. ‘Bare’ ions without chelating agents are not allowed through the membrane. By the way, we all face various chelating agents in our routine almost every day: these substances are added to various cleaning means, detergent, shampoos and cosmetics. Chelating agents are used in various chemical analyses, as well as for restoration of archeological findings — these agents often eliminate the worst rust.
“Our calculations and experiments have shown a plausible mechanism of multi-functional complex organics generation within the interstellar ice in the deep space. It fundamentally expands the knowledge of the attainable level of molecular complexity in space. The obtained molecules can actually function as prebiotic chelating agents that once came to the Earth with the meteorites and comets and facilitated transportation of ions into primitive cells which eventually accelerated RNA replication and the widespread of early life forms,” Ivan Antonov emphasized.
* Samara National Research University is a participant of the Science and Universities National Project.
*A ribonucleic acid (RNA) is one of three main macromolecules (along with DNA and proteins) contained in cells of all living organisms to play an important part in gene codification, reads, regulation and expression. It’s RNA that forms genome of some viruses, including, for instance, coronaviruses.
*In the nearest future, it is planned to conduct some experimental researches in Samara as well to find out how biochemically significant organic compounds in our Galaxy. For this purpose a unique installation currently created in the Centre of Laboratory Astrophysics of the Samara branch of the Lebedev Physical Institute of RAS (LPI RAS, SB) will be used. The installation will help not only explore the evolution of organic molecules in our Galaxy, but also test the promising metals that can be potentially used in spacecraft and satellite skin for radiation damage stability. The works on the assembly of equipment are carried out by scientists of the Samara branch of LPI and the Samara University. The installation is planned to be put into commission till the end of 2023.