On regularities in the spontaneous formation of structural hierarchies in chiral systems of nonliving and living matter

Chiral Dualism as an Instrument of Hierarchical Structure Formation in Molecular Biology

“…Eventually the same principles can be applied even to artificial systems. A unifying biophysical basis of these phenomena was discussed earlier by the authors [19][20][21][22]. Here we propose that homochirality may serve as an essential factor that invokes the physical and chemical mechanisms required to control the formation of discrete structural hierarchies in macromolecules and macromolecular assemblies, even determining to a large extent their function, like in the case of macromolecular machines.…”

“…In other words, the hierarchies of structural levels of organization of proteins and nucleic acids in cells, normally described qualitatively, may instead be represented as a regular interconnected chiral system. Starting from the level of an asymmetric carbon atom in the amino acids of the primary structure of a protein and in DNA deoxyribose, we earlier noted that there is a tendency to switch the chirality sign at subsequent structural levels, resulting in sequences of the types L-D-L-D in proteins and D-L-D-L in DNA [19][20][21][22]. An interesting manifestation of this principle is found in helical structures.…”

“…The formation of chiral sign-alternating hierarchical structures in initially homochiral systems is not an exclusive property of biological organisms; it can be reliably reproduced in various polymeric and liquid-crystalline systems [20,22]. For example, a thermodynamically governed process of racemization of any macroscopic homochiral system leads to the elimination of chiral polarization of substances in solutions of compounds of nonbiological origin, which in turn results in suppression of the spontaneous formation of a succession of chiral structures [32].…”

Chiral Dualism as a Unifying Principle in Molecular Biophysics

“…Starting from the level of an asymmetric carbon atom in the amino acids of the primary structure of a protein and in DNA deoxyribose, we have earlier noted that there is a tendency to switch the chirality sign at the subsequent structural levels, resulting in a sequence of the type "left-handed"-"right-handed"-"left-handed"-"right-handed" in proteins ( Figure 1) and "right-handed"-"left-handed"-"right-handed"-"left-handed" in DNA [89][90][91]. The chirality sign alternates during the transition to higher-order structures of DNA structural and functional organization in A-and B-forms.…”

“…The study of systems demonstrating a change in helicity sense is actively developing at present [92][93][94][95][96]. We mentioned earlier that the chirality of molecules or macroscopic objects is not a feature, but one of the general and fundamental structure-forming factors in both living and non-living nature [89][90][91]. On the other hand, it has been observed that artificially created homochiral systems may undergo the same process of spontaneous formation of hierarchies of molecular and supramolecular structures with an alternating chirality sign.…”