Three short chain peptides of general formula Cys-AA-CSA where CSA is cystamine AA is Gly Ala or Pro were synthesized and used for the determination of the electron transmission through individual amino acid residues The conductance measurements were carried out using STM-based molecular Junction method The results of our comparative study indicate that the ability of these molecules to mediate electron transfer is not significantly affected by the presence of the methyl side chain in alanine or the cyclic structure of proline Thus the efficiency of electron transmission is determined mostly by the peptide backbone structure (C) 2010 Elsevier B V All rights reserved