A bis-histidine-ligated unfolded cytochrome c immobilized on anionic SAM shows pseudo-peroxidase activity

作者：Ranieri Antonio; Battistuzzi Gianantonio; Borsari Marco^*; Bortolotti Carlo Augusto; Di Rocco Giulia; Monari Stefano; Sola Marco

来源：Electrochemistry Communications, 2012, 14(1): 29-31.

DOI：10.1016/j.elecom.2011.10.021

• Cytochrome c
• Peroxidase activity
• Self-assembled monolayer
• Urea
• Unfolding

Urea-unfolded yeast iso-1-cytochrome c electrostatically adsorbed on a gold electrode coated with an anionic self-assembled monolayer yields a heme-mediated electrocatalytic reduction of H2O2 (pseudo-peroxidase activity). Under the same conditions, native cytochrome c is inactive. In the unfolded protein, the Met80 heme iron ligand is replaced by a histidine residue yielding a bis-His-ligated form. H2O2 electrocatalysis occurs with an efficient mechanism likely involving direct H2O2 interaction with the iron(II) center and formation of a transient ferry! group. Comparison of the catalytic activity of a few urea-unfolded single and double Lys-to-Ala variants shows that the kinetic affinity of H2O2 for the heme iron and k(cat) of the bis-His-ligated form are strongly affected by the geometry of protein adsorption, controlled by specific surface lysine residues.

• 出版日期2012-1