Quantitative Criteria of Chirality in Hierarchical Protein Structures

Resumo

Based on the theory of the formation of sign-alternating hierarchical structures in macromolecular systems, a quantitative approach was developed to assess the chirality sign of individual levels in hierarchical protein structures. Quantitative estimates are necessary for modeling the folding of proteins and their function as molecular machines. Mutual attraction between the α-carbon atoms of amino acids is a sufficient condition for characterizing the level in the hierarchical structure and determining the chirality sign of protein blocks. A quantitative estimate of the twist in helical (secondary) and superhelical (tertiary) structures is provided by the absolute value of the sum of vector cross products. The sign of the scalar product of the direction vector to the vector of the sum of vector products indicates the direction of the twist. Chiral maps were constructed for the secondary and tertiary structures of several proteins. The reliability of the maps was confirmed by analyzing the respective real structures.