Constructed a new theory of the origin of life on Earth, according to which the transition from heterogeneous organic molecules to the first living organism includes four interrelated evolutionary stages. In the first stage formed molecular systems that convert the energy of UV light into chemical energy, in the second and the third was complicated by the structural and functional organization of these systems was the selection of components, increased energy potential, while living cells were formed on the fourth. For each phase identified conditions and driving forces of the processes of self-development, structural and functional organization of objects and mechanisms of resistance evolution. This theory gives the integrity and completeness of the scientific notions of abiogenesis. It contributes to the deepening of knowledge about the structure of living matter, expanding the horizons of practical biology and medicine.
Four stages of abiogenesis
Many scientists lost interest in the problem of the origin of life, as they find that it is almost solved, and you only find out what comes first: the selection of nucleic acids (DNA, RNA), carrying genetic information, or spontaneous concern radio enzymes capable of extracting information from DNA? In fact, a standard dilemma – “The chicken or the egg.” Neither one nor the other does not explain the origin of living matter, because the reading of information encoded in the DNA, it is impossible without the continuous reproduction of the same enzymes, which, in turn, is impossible without reading the genetic information in the matrix synthesis of protein molecules.
Based on current knowledge about the chemical constituents and physical properties of water bodies and the atmosphere of ancient Earth, we have constructed a theoretical model of the origin of life, focuses on the history of molecular energy systems. According to this model, biologically significant chain poly-NK polypeptides and globules initially selected as components of molecular films that absorb UV energy. Later these films formed from multilayered structure that guided UV energy for synthesis of ATP and other molecules macroergs. Its catalytic activity is increased, which led to the appearance of its internal environment isolated areas differ in chemical composition. Thereafter formed matrix conditions for initiating synthesis of RNA and polypeptides. Thus were born the first living cells with genetic information around the clock and metabolism.
About four billion years ago on Earth appeared reservoirs, which formed the so-called primordial soup. There were many organic compounds: amino acids, nitrogenous bases, nucleotides, nucleic acid synthesis possibility … upon heating, electric discharges irradiation confirmed experimentally [2, 3]. The ancient atmosphere contained no oxygen and passed the UV radiation in the range of 240 – 260 nm, absorbed by many organic compounds. Under the influence of UV-light in some of these molecules have occurred various structural changes, which depend on the character of the intramolecular and intermolecular energy transfer. It is necessary to determine which energy transfers contributed to the selection of organic molecules primordial soup.
In the mid 60-ies of the triplet-exciton energy transfer has been opened in nucleic acids [4, 6, 7]. This process starts when one of the nitrogenous bases of the polynucleotide chain composed of RNA or DNA absorbs UV-light (254nm). It moves to the excited triplet state, and then transfers the energy adjacent the base and itself returns to the unexcited state. Energy transfer in the chain is the coincidence of the quantum properties of neighboring nitrogen bases and optimal distances between them. These conditions are fulfilled in the biological DNA or RNA consisting of a standard set of four nitrogenous bases – A, G, C, U (T) connected by 3′-5 ‘linkages. Proved experimentally [6, 7], that the nucleic acids, which have heterogeneity at the primary structure, the triplet exciton transfer leading to destructurization not occurring at the points of UV absorption, and in areas with internal predisposition.
In ancient reservoirs were poly-NC with a different primary structure. In the absorption of UV light those fragments, which went smoothly triplet exciton energy transfer, remained unchanged, i.e., they were resistant to UV light. Others were subjected to reparation and conformational changes. Or them can form new stable chain? In this way, increased the number of RNA molecules that are similar based on their performance energy transfer.
It is important to bear in mind that the stability of the UV-irradiated poly-NK depends not only on the orderly intramolecular transfer, but also on the outflow of energy outward. In organic molecules in an aqueous environment, energy outflow is realized with inductive-resonant interactions, which require that the distance between the energy donor and the acceptor does not exceed a certain threshold (about 100A), and the spectral band of the fluorescence of the donor overlap with the absorption band of the acceptor. Many organic compounds have the appropriate primary broth spectral absorption band, but their participation in the inductive resonance shifts as energy acceptors prevented distance between them and UV-activated RNA. In living cells, the molecules closer to the donor-acceptor molecules with inductive resonance shifts provide enzymes. They are formed from polypeptides synthesized by the matrix, which have a predetermined primary, secondary and tertiary structure. Without massive matrix synthesis of polypeptides enzymatic processes are impossible.
The primordial soup was not full of enzymes, but there were diverse “wild” polypeptides. When dealing with a UV-activated RNA, they played the role of the acceptor inductive resonance energy transfers and subjected to stress, change their primary, and with it the tertiary structure. We hypothesized that, despite the restructuring of randomness, some of the polypeptides appear similar active sites that allow them to attach molecules suitable substrates and to hold them in zones of inductive resonance shifts as energy acceptors. At the RNA chain, absorbs UV rays and serves as an energy donor, these polypeptides were stable nucleoprotein complexes that transfer energy to the molecules-related substrates, and thus initiated the photocatalytic conversion of their structures. (Fig. 1).
Realizing the photocatalysis in the composition of stable nucleoprotein complexes, polypeptides received protection from the new restructuring. Selection functionally similar polypeptides suitable for photocatalysis, was pressurized to UV light. If for some reason lost the substrate specificity of the polypeptides necessary for photocatalysis, they returned to the role of energy acceptors. Now they are again exposed to structural change, so could reclaim their substrate specificity.
On stability, photocatalytic complexes formed in the primary broth affect their location in an aqueous medium, the orientation to the flow of UV light. There great advantage afforded selective formation of floating films which not only consisted of a UV-absorbing and substrats-making, but also of the coupling elements. The latter role was performed lipids capable of spontaneously forming a film structure.
If RNA were included with the photocatalytic complexes had an annular secondary structure, which was in circulation triplet excitons. This lengthens the time of interaction with the acceptor molecules, and the energy of the UV light transmitted pulses acceptors on the principle of self-oscillation. RNA Ring dominated the assembly of stable complexes and films, and other polynucleotides, staying out of the complex, is not provided with energy acceptors themselves exposed to UV-induced degradation.
Nucleoprotein complexes, such originated in the primordial soup, play a leading role in the catalytic systems of all living cells. This “building blocks” of living matter. Note that one of the most important properties of living matter is dynamic. The cells are constantly decay and self-assembly of many substructures having metastable intermolecular bonds that remain due to the energy dissipation. In ancient photocatalytic complexes also were metastable connection polypeptides with poly-NC, preserved only in the course of an active energy transmission with photocatalysis. Therefore, these complexes night broke, and the day was repeated self-assembly. Cyclical subordinate circadian rhythm, improve their variability, accelerated selection.
To be continued soon…