Beatrice Bonanni | PubMed Health

PubMed2003

Topological and electron-transfer properties of yeast cytochrome c adsorbed on bare gold electrodes.

The redox metalloprotein yeast cytochrome c was directly self-chemisorbed on "bare" gold electrodes through the free sulfur-containing group Cys102. Topological, spectroscopic, and electron transfer properties of the immobilised molecules were investigated by in situ scanning probe microscopy and cyclic voltammetry. Atomic force and scanning tunnelling microscopy revealed individual protein molecules adsorbed on the gold substrate, with no evidence of aggregates. The adsorbed proteins appear to be firmly bound to gold and display dimensions in good agreement with crystallographic data. Cyclic voltammetric analysis showed that up to 84% of the electrode surface is functionalised with electroactive proteins whose measured redox midpoint potential is in good agreement with the formal potential. Our results clearly indicate that this variant of cytochrome c is adsorbed on bare gold electrodes with preservation of morphological properties and redox functionality.

Computational Biology↗

PubMed2003

A combined atomic force microscopy and molecular dynamics simulation study on a plastocyanin mutant chemisorbed on a gold surface.

A mutant of copper plastocyanin, covalently bound to an Au (111) surface through an engineered disulfide bridge, was investigated in aqueous medium by atomic force microscopy (AFM) and molecular dynamics (MD) simulations. Tapping-mode AFM images revealed adsorption of single molecules which are homogeneously distributed over the substrate and strongly bound to gold and display uniform lateral size. A statistical analysis of the height of the macromolecules on the gold substrate evidenced a distribution around a mean value consistent with that expected from the crystallographic data and with a relatively large standard deviation. A 10-ns classical MD simulation of mutated plastocyanin, hydrated by a layer of water, covalently bound to a gold surface by one or two sulfur atoms, was performed. The simulations indicate that the bound protein retains, in both cases, its overall tertiary structure during the dynamic evolution. Moreover, the macro-molecule can assume different orientations with respect to the gold substrate, which give rise to a distribution of heights on the gold substrate. Experimental and MD simulation results are compared and discussed in connection with the topological and dynamical properties of the protein system.

Adsorption↗