Astronomers have long known that there are many different types of organic matter in space. But how complex and, most importantly, how close to biological molecules can “extraterrestrial organics” be? The authors of a new paper in the journal Science Advances have demonstrated that peptides, polymers of amino acids close to proteins, can be successfully obtained under conditions typical of cold dust clusters in interstellar space.

One of the most interesting and at the same time most difficult problems of modern natural science is abiogenesis, that is, the origin of life on the basis of non-living components. Over the past century, scientists have proposed a number of hypotheses that partially explain abiogenesis, but these are flawed and pure speculation.

The first and generally the simplest step on the path to abiogenesis is the emergence of molecules at the base of a living cell: DNA, RNA and proteins. Experiments showing the fundamental possibility of “self-assembly” of amino acids, the structural units of proteins, were carried out in 1953 by S. Miller and G. Yuri. However, it is now clear that they used conditions that could not have existed in the Ancient World. Additionally, the experiment does not explain the formation of larger polymers from amino acids (proteins and smaller similar molecules, peptides).

Authors of the new article Science Developments He proposed that peptides, that is, short chains of amino acids, could arise spontaneously in deep space conditions, in interstellar space. We are talking about clusters of light-transmitting dust where cosmic frost prevails (about minus 260 degrees Celsius), where stable molecules, including water in the form of ice, are present. Comets and asteroids are formed from this material; The first of these involves less change and contains substances close to their original state.

Comets and other cosmic bodies are known to regularly collide with the Earth and other objects in the solar system. Such “collisions” were especially frequent during heavy bombardment 4.1-3.8 billion years ago. It is possible that meteorites that fell at that time “fertilized” the Earth with various organic substances, including such compounds that could not form on the planet itself. According to modern ideas, the first living cells soon appeared on Earth.

Peptides and proteins aroused special interest of the authors, because without them it is difficult to imagine the main functions of the cell – acceleration of chemical reactions and duplication of their structure. Modern living things synthesize such molecules inside their cells, in special organelles (ribosomes) that use RNA as a matrix. But none of this would be possible on Earth.

This paradox can be allowed by assuming that the first peptides with catalytic properties came readily from space. Therefore, scientists recreated conditions corresponding to gas clouds in interstellar space and carried out chemical reactions within them involving atomic carbon-13, carbon monoxide and ammonia. The reaction was initiated at a temperature of approximately minus 263 degrees Celsius and ramped up to 27 degrees. We used labeled carbon with atomic mass 13 to avoid confusing the reaction products with ordinary organic substances.

As a result, the experimenters obtained a series of peptides consisting of the simplest amino acid, glycine. Not all of them obtained the standard carboxyl and amino termini for biological molecules; the vast majority had two amino groups on their edges.