The Role of Electron Spin-Polarizability and Charge Dynamics in Protein Function

Abstract

AbstractWe investigated the association of two model primordial polypeptides, each bearing an ancient and ubiquitous phosphate-binding motif, with DNA. The association rate and the amount of bound DNA relates to the electron spin-dependent polarizability of the binding protein. Contributions to protein polarizability are also made by residues that are far from the spin injection site. The spin-dependence is associated with the chirality of the proteins and is a consequence of chiral-induced spin selectivity (CISS). Since the polypeptides studied are hypothesized to be among the initial stand-alone ‘seed’ fragments from which contemporary protein domains evolved, the results suggest the importance of spin-dependent polarizability early in protein evolution. As the spin effect is a direct consequence of biopolymer homochirality, it was likely significant from even the earliest stages of biological evolution. We provide model calculations clarifying the underlying reasons for spin selectivity and estimating its impact on protein function.