Role of Stereochemistry on Electron Transport in Peptides

Stereochemistry underlies structure–function relationships across biology and materials science. Here, we investigate electron transport in oligopeptide stereoisomers using single-molecule experiments and computational modeling. Our results show that stereochemical modifications in tyrosine-based peptides lead to significant variations in molecular conductance and transport distance along the peptide backbone, associated with changes in aromatic side-chain interactions and electronic coupling. In alanine-based peptides, stereochemical modifications alter molecular conductance through secondary-structure interactions associated with β-turn conformations. Molecular dynamics simulations and quantum mechanical calculations reveal the molecular origins of these stereochemistry-dependent structural and electronic properties. Overall, this work shows that stereochemical modification of nonterminal amino acids provides a means to control electron transport through distinct mechanisms involving aromatic side-chain interactions and secondary structure. These results establish stereochemistry as a molecular design parameter for controlling electron transport in peptide-based electronic materials.