Probing the Bioinorganic Chemistry of Cu Spectroscopy

• Published in: Inorganics 2023-09, Vol.11 (10)
• Main Authors: Karner, Victoria, Jancso, Attila, Hemmingsen, Lars
• Format: Article
• Language: English
• Subjects: Copper; Properties; Silver; Structure
• ISSN: 2304-6740
• DOI: 10.3390/inorganics11100375

The two most common oxidation states of copper in biochemistry are Cu(II) and Cu(I), and while Cu(II) lends itself to spectroscopic interrogation, Cu(I) is silent in most techniques. Ag(I) and Cu(I) are both closed-shell d[sup.10] monovalent ions, and to some extent share ligand and coordination geometry preferences. Therefore, Ag(I) may be applied to explore Cu(I) binding sites in biomolecules. Here, we review applications of [sup.111] Ag perturbed angular correlation (PAC) of γ-ray spectroscopy aimed to elucidate the chemistry of Cu(I) in biological systems. Examples span from small blue copper proteins such as plastocyanin and azurin (electron transport) over hemocyanin (oxygen transport) to CueR and BxmR (metal-ion-sensing proteins). Finally, possible future applications are discussed. [sup.111] Ag is a radionuclide which undergoes β-decay to [sup.111] Cd, and it is a γ-γ cascade of the [sup.111] Cd daughter nucleus, which is used in PAC measurements. [sup.111] Ag PAC spectroscopy may provide information on the coordination environment of Ag(I) and on the structural relaxation occurring upon the essentially instantaneous change from Ag(I) to Cd(II).