Université de Fribourg

Electron transfer in peptides: on the formation of silver nanoparticles

Kracht, Sonja ; Messerer, Matthias ; Lang, Matthieu ; Eckhardt, Sonja ; Lauz, Miriam ; Grobéty, Bernard ; Fromm, Katharina M. ; Giese, Bernd

In: Angewandte Chemie International Edition, 2015, vol. 54, no. 10, p. 2912–2916

Some microorganisms perform anaerobic mineral respiration by reducing metal ions to metal nanoparticles, using peptide aggregates as medium for electron transfer (ET). Such a reaction type is investigated here with model peptides and silver as the metal. Surprisingly, Ag⁺ ions bound by peptides with histidine as the Ag⁺-binding amino acid and tyrosine as photoinducible electron donor cannot...

Université de Fribourg

pH-dependent coordination of AgI ions by histidine: experiment, theory, and a model for SilE

Mirolo, Laurent ; Schmidt, Tobias ; Eckhardt, Sonja ; Meuwly, Markus ; Fromm, Katharina M.

In: Chemistry - A European Journal, 2013, vol. 19, no. 5, p. 1754–1761

Artificial implants and biomaterials lack the natural defense system of our body and, thus, have to be protected from bacterial adhesion and biofilm formation. In addition to the increasing number of implanted objects, the resistance of bacteria is also an important problem. Silver ions are well-known for their antimicrobial properties, yet not a lot is known about their mode of action. Silver is...

Université de Fribourg

Radicals and radical ions as intermediates of electron transfer processes through peptides

Giese, Bernd ; Eckhardt, Sonja ; Lauz, Miriam ; Gao, Jian ; Wang, Min

In: Chimia, 2012, vol. 66, no. 6, p. 364-367

Electron transfer (ET) through peptides and proteins is a key biochemical process, which involves radicals and radical ions as reactive intermediates. We have developed an assay that allows us to study this fundamental chemical reaction.

Université de Fribourg

The influence of dipole moments on the mechanism of electron transfer through helical peptides

Lauz, Miriam ; Eckhardt, Sonja ; Fromm, Katharina M. ; Giese, Bernd

In: Physical Chemistry Chemical Physics, 2012, vol. 14, no. 40, p. 13785-13788

The life time of aromatic radical cations is limited by reactions like β-elimination, dimerization, and addition to the solvent. Here we show that the attachment of such a radical cation to the C-terminal end of an α-/3₁₀-helical peptide further reduces its life time by two orders of magnitude. For PPII-helical peptides, such an effect is only observed if the peptide contains an adjacent...