Density Functional Theory and Information-Theoretic Approach Study on the Origin of Homochirality in Helical Structures

Homochirality of macromolecules such as proteins and DNA is one of the most striking features in nature; yet, there is still no convincing theory to explain its origin. In a recent work by one of the present authors (J. Phys. Chem. Lett. 2020, 11, 8690-8696), a general proposal from the viewpoint of thermodynamics has been put forward. It proposes that it is the handedness of helices ubiquitous in biological macromolecules that plays the decisive role. It also unveiled that there exist strong cooperativity effects dominated by favorable electrostatic interactions in the homochiral conformer. In this work, making use of analytical tools, we recently developed a density functional theory and an information-theoretic approach and through four sets of helical structures we designed for the present study, we examine these systems to provide new insights about these properties. We found that the 3(10)-helix and the a-helix are markedly different in cooperativity from the viewpoint of both the total energy and its three components. The electrostatic dominance of homochiral species is manifested by both the electron charge distribution and information gain. At the atomic level, different elements behave significantly differently because they play different roles in the systems. Our results from this work validate that these analytical tools can be applied to homochiral systems, which can be further extended to others with potential interest in asymmetric synthesis and macromolecular assembly where the Principle of Homochirality Hierarchy comes into play.