MOSCOW, September 20. Scientists at Samara University, as part of an international team, have found out why and how, already at the stage of star formation, a large number of sugar molecules are formed, which are the main source of energy in living organisms. They managed to reproduce cosmic interstellar ice in a scientific laboratory. The data obtained indicate a high probability of the cosmic origin of complex organic molecules, which are the initial building blocks of living organisms on Earth. The results are presented in The Journal of Physical Chemistry Letters.
As scientists reported, molecules of the sugar class are an integral part of all life on Earth: they participate in the synthesis of RNA and DNA, forming the backbone of the genome, and are also a vital source of energy in living organisms. They are a chain of carbon atoms to which alcohol groups and hydrogen atoms are attached, and this skeleton ends with an aldehyde group — a hydrogen and oxygen atom attached by a double bond to the last carbon atom in the chain.
< /span>
The origin of these rather complex molecules in structure, and even more so their acquisition of significance for earthly creatures, is a complex scientific question, to answer which many hypotheses have been formed. Scientists detect the simplest sugar molecules (with just three carbon atoms) on the surface of some meteorites falling to Earth, and also detect their presence when observing interstellar ice.
Because the temperature in the densest parts of the molecular clouds in interstellar space are on the order of 5–10 K (from -268 to -263 ° C. — Ed.), the matter in them is concentrated mainly in the form of solid particles covered with icy mantles — the so-called cosmic ice. Complex organic molecules, including prebiotic ones, are formed in them under the influence of hard galactic radiation.
Among these “cosmic” substances there are mainly quite simple molecules, for example methyl alcohol (CH3OH) or acetaldehyde (CH3CHO). These are combinations of the most frequently occurring molecules in our Galaxy.
It is from methanol and acetaldehyde that the simplest sugar can be synthesized in the “correct” form — hemiacetal (R/S)-1-methoxyethanol. Scientists from Samara National Research University named after Academician S.P. Korolev (Samara University) and the Samara branch of the P.N. Physical Institute. Lebedev RAS, within the framework of the megagrant “The Origin and Evolution of Organic Molecules in Our Galaxy,” together with American colleagues, proved that such a process actually occurs even at extremely low cosmic temperatures.
The process of sugar formation was both modeled theoretically and reproduced experimentally.
«To conduct the experiment, we used an installation in which an ultra-high vacuum was maintained and ice was recreated at a temperature of several Kelvin, bombarded with high-energy particles. Next, we looked at what chemical transformations occur during this,” said Samara University graduate student Anatoly Nikolaev.
< /span>
According to him, such hemiacetals can act as precursors of interstellar sugars and related molecules when exposed to ionizing radiation.
“Complex molecules are formed already at the stage of star formation, in cryogenic ice, and are then included in planetoids, asteroids and comets. Detailed analysis of meteorites has shown that biologically important molecules such as ribose were able to survive the harsh conditions of space. Consequently, some of these complex molecules may have been delivered to the early Earth and served as an exogenous source of biomolecules, providing a likely additional route to the formation biologically important molecules at the earliest life stage of our planet,” he specified.
Samara University is a participant in the state support program for universities of the Russian Federation «Priority 2030».