The RNA World: the first step

Experimental confirmation of the RNA-world hypothesis has been obtainedDmitry Safin, "Kompyulenta"
A group of scientists from the University of Manchester (England) managed to synthesize a ribonucleotide (a compound necessary for the formation of RNA) in external conditions comparable to the conditions of the primitive Earth, and on the basis of molecules that were most likely in the primary broth.

Proponents of the RNA-world hypothesis believe that at the initial stage of the origin of life on our planet, autonomous RNA systems arose that catalyzed "metabolic" reactions (for example, the synthesis of new ribonucleotides) and reproduced themselves. The accumulation of random mutations should have led to the appearance of RNAs that catalyze the synthesis of more "efficient" molecules, as a result of which these mutations were fixed during natural selection. In the process of further evolution, it is claimed that modern protein life arose.

Unfortunately, this slender hypothesis has its drawbacks. Its opponents pointed out that the formation of ribonucleotides, during polymerization of which RNA is formed, in the "traditional" way — from the residue of phosphoric acid, ribose sugar and nitrogenous base — could hardly have occurred in natural conditions.

English researchers have proved that the synthesis of ribonucleotides can be carried out in another way, without the participation of ribose and bases. To carry out the reaction proposed by scientists, cyanamide (indicated by the number 4 in the diagram), cyanoacetylene (3), glycolic aldehyde (7), glyceraldehyde (6) and inorganic phosphate (2) are required — molecules whose presence on the primitive Earth is estimated as very likely. (In the scheme of ribonucleotide synthesis, the green arrows show the described process, the blue ones show the previous version, the course of which was interrupted at the stage indicated by the red cross.)

At the beginning of the process, glycolic aldehyde reacts with cyanamide, forming an intermediate compound — 2-aminooxazole (5). Periodic heating by sunlight and lowering the temperature during the night period make it possible to purify 2-aminooxazole, turning it into a "substitute" for sugar and a nitrogenous base. Under the influence of UV radiation in the presence of inorganic phosphate, the process ends with the formation of a ribonucleotide (1).

Colleagues of scientists appreciated the results of their work. "This study can be considered one of the main achievements of the chemistry of the prebiological stage of the Earth's development," said Jack Szostak, an American specialist.

The full version of the scientists' report is published in the journal Nature.

Prepared based on the materials of Physorg.

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