β-turn,as a second structure of protein,is considered that it is not just as ascaffold supporting the protein conformations but as an efficient,significant mediumof charge hopping transfer events.Different from large loops which have been researched in our previous work1,β-turn structure involves three amino acids with a hydrogen bond between the i and i + 3 residues.Therefore,we present a densityfunctional theory2 computational study to clarify the charge relaying properties of β-turn.The ability of the simplest tripeptide β-turn structure to act as a charge relay is not strong and even extremely weak.We link a β-strand to the C-terminus of β-turn to constitute a hook-like structure(I),in which the electron-binding ability of β-turn N-terminus enhances greatly with the strand elongation,evidenced by continually increasing electron affinity(EA).Meanwhile,the similar elongation of the N-terminus of β-turn could form another hook-like structure(II),in which the electron-losing and hole-forming ability of the β-turn C-terminus becomes stronger and stronger as the number of peptide units increases,evidenced by decreasing ionization potential(IP).In the two hook-like structures,the β-strand also plays a non-ignorable role in competing and cooperating with β-turn fragment.In the β-hairpin configurations,abilities to server as charge relays for β-turn degenerate severely owing to the weak polarity which is attributed to the high symmetry of antiparallel β-sheet structure.Thus,it is joint effect of macro-dipole and local dipoles,which determines the relay properties in these structures to facilitate long-range charge transfer in proteins.