Cytochrome c is a protein that transports electrons from cytochrome c reductase to cytochrome c oxidase found in the mitochondria of cells. The movement of electrons in the electron transport chain can be mimicked in vitro using cytochrome c adsorbed to self-assembled monolayers (SAMs) covalently bonded to evaporated gold. Many papers have been published investigating the interaction of cytochrome c with carboxylic acid terminated alkanethiol films on gold. Since cytochrome c interacts with protein in the electron transport chain, a better interaction surface to mimic the natural system would be peptide SAMs. Electrodes were constructed to evaluate cytochrome c thermodynamics and kinetics by assembling the peptide on evaporated gold/glass. Cytochrome c adsorbs to the peptide SAM because the terminal end of the SAM exposed to solution has a net negative charge and attracts the positively charged lysine groups in the cytochrome c similar to the redox partners in vivo. The purpose of this research is to become more familiar with the interaction between peptide SAMs and cytochrome c to investigate electron transfer enhancement by the peptide protein interaction. The peptide SAM studied was comprised of glutamic acid, alanine, and cysteine. These amino acids were chosen to create a height similar to that of previous alkanethiol SAMs. The data obtained will be compared to past research using alkanethiol SAMs. The current full monolayer cytochrome c/peptide data shows the cytochrome c on the peptide SAMs has a slower electron transport rate than cytochrome c on the 50/50 carboxylic acid alkanethiol SAMs but faster than pure carboxylic acid SAMs. The peptide SAMs being tested also showed a higher background capacitance in the cyclic voltammograms. In addition to full peptide monolayer SAMs, mixed monolayers of peptide and shorter chain alkanethiols have been explored. Several different peptide SAMs were synthesized and will be compared to see if there is a better sequence to enhance cyt c electrochemistry. Results will be presented for all of the cytochrome c/peptide monolayers investigated.

Cytochrome c adsorbed to peptide SAM modified evaporated gold electrodes

2019 Spring National Meeting

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