Chirality as an Instrument of Stratification of Hierarchical Systems in Animate and Inanimate Nature

Abstract

The article seeks to formulate a synergetic law that is posited to be of common physicochemical and biological nature: an evolving system, possessing free energy and elements with chiral asymmetry may change the type of symmetry inside one hierarchical level, thereby increasing its "complexity", but preserving the sign of predominant chirality ("right"-D or "left"-L twist). The same system has a tendency to spontaneous formation of a succession of hierarchical levels with alternating chirality sign of de-novo formed structures and with an increase of the structures' relative scale. In the living systems the hierarchy principle of conjugated levels of macromolecular structures, starting with the "lower" level of asymmetrical carbon, serves as an anti-entropic factor and also as the structural basis of the "selected mechanical degrees of freedom" in the molecular machines. Observations present evidence of regular alternations of the chirality sign D-L-D-L and L-D-L-D for DNA and protein structures, respectively, during the transition of DNA and proteins to a higher level of structural and functional organization. Sign-alternating chiral hierarchies of DNA and proteins, in turn, form a complementary conjugated pair that is an achiral invariant, which closes a molecular biological module of living systems. The ability of a carbon atom to form chiral compounds is a significant factor that defined carbon basis of living systems on Earth, and also their development via succession of chiral bifuractions. Restricted by the chirality sign, the hierarchy principle of macromolecular structures determined the "modular" character of biological evolution.