Electron Transfer Proteins as Electronic Conductors: Significance of the Metal and Its Binding Site in the Blue Cu Protein, Azurin.

摘要: Electron transfer (ET) proteins are biomolecules with specific functions, selected by evolution. As such they attractive candidates for use in potential bioelectronic devices. The blue copper protein azurin (Az) is one of the most-studied ET proteins. Traditional spectroscopic, electrochemical, and kinetic methods employed studying to/from protein's Cu ion have been complemented more recently studies electrical conduction through a monolayer Az solid-state, sandwiched between electrodes. latter type measurement does not require involvement redox process, it also allows monitoring electronic transport (ETp) via redox-inactive Az-derivatives. Here, results macroscopic ETp redox-active -inactive derivatives, i.e., Cu(II) Cu(I)-Az, apo-Az, Co(II)-Az, Ni(II)-Az, Zn(II)-Az reported compared. It found that earlier temperature independence Cu(II)-Az (from 20 K until denaturation) unique, as all other derivatives thermally activated at temperatures >≈200 K. Conduction Cu(I)-Az shows unexpected dependence K, currents decreasing positive increasing negative bias. Taking data together we find clear compensation effect around denaturation temperature. This can be understood viewing binding site an electron trap, unless occupied Cu(II), native protein, setting upper efficiency limit.