The origin and potential role of chiral asymmetry remain one of the most exciting issues in biology. In this paper we review the chirality of biological macromolecules, starting at the level of single molecules and continuing to the level of supramolecular assemblies. We discuss the physical and chemical consequences of the presence of chirality and their role in the self-organization and formation of structural hierarchies in cells. Homochirality may serve as an essential factor that invokes mechanisms required to control the formation of discrete structural hierarchies in macromolecules and macromolecular assemblies. Symmetry is of fundamental importance not only for all molecular biology as a systemic factor of its organization but also for pharmacology, as well as a systemic factor of drug stereospecificity.

The quantitative evaluation of the chirality of macromolecule structures remains one of the exciting issues in biophysics. In this paper, we propose methods for quantitative analysis of the chirality of protein helical and superhelical structures. The analysis of the chirality sign of the protein helical structures (α-helices and -helices) is based on determining the mixed product of every three consecutive vectors between neighboring reference points—α-carbons atoms. The method for evaluating the chirality sign of coiled-coil structures is based on determining the direction and value of the angle between the coiled-coil axis and the α-helices axes. The chirality sign of the coiled coil is calculated by averaging the value of the cosine of the corresponding angle for all helices forming the superhelix. Chirality maps of helical and superhelical protein structures are presented. Furthermore, we propose an analysis of the distributions of helical and superhelical structures in polypeptide chains of several protein classes. The features common to all studied classes and typical for each protein class are revealed. The data obtained, in all likelihood, can reflect considerations about molecular machines as chiral formations.

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