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Electron Transfer through H-bonded Peptide Assemblies

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journal contribution
posted on 30.12.2004, 00:00 by Heinz-Bernhard Kraatz, Irene Bediako-Amoa, Samuel H. Gyepi-Garbrah, Todd C. Sutherland
A series of ferrocene (Fc)- and cystamine (CSA)-labeled peptides of the sequence [Fc-(Pro-Pro-Gly)n-CSA]2, where n = 1−3, was synthesized and characterized. Peptide 3 forms a trimeric supramolecular structure held together with extensive hydrogen bonding and adopts a collagen-like motif in solution. Cyclic voltammetry (CV) and chronoamperometry (CA) were used to calculate electron-transfer (ET) kinetics. ET rates were 10.9 (2.3) × 103, 6.6 (1.9) × 103, and 4.2 (1.2) × 103 s-1 for peptides where n = 1, 2, and 3, respectively. The peptides, under deuterated conditions (D2O, full exchange of H for D), showed rate constants of 7.3 (1.3) × 103, 5.8 (1.0) × 103, and 3.4 (0.5) × 103 s-1 for n = 1, 2, and 3, respectively. A linear dependence of the ET rate constant and distance is found.

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