Probing the Paradigm of Promiscuity for N‐Heterocyclic Carbene Complexes and their Protein Adduct Formation

Abstract

Metal complexes can be considered a “paradigm of promiscuity” when it comes to their interactions with proteins. They often form adducts with a variety of donor atoms in an unselective manner. We have characterized the adducts formed between a series of isostructural N‐heterocyclic carbene (NHC) complexes with Ru, Os, Rh, and Ir centers and the model protein hen egg white lysozyme by X‐ray crystallography and mass spectrometry. Distinctive behavior for the metal compounds was observed with the more labile Ru and Rh complexes targeting mainly a surface l‐histidine moiety through cleavage of p‐cymene or NHC co‐ligands, respectively. In contrast, the more inert Os and Ir derivatives were detected abundantly in an electronegative binding pocket after undergoing ligand exchange of a chlorido ligand for an amino acid side chain. Computational studies supported the binding profiles and hinted at the role of the protein microenvironment for metal complexes eliciting selectivity for specific binding sites on the protein.

Increasing the cytotoxicity of Ru(ii) polypyridyl complexes by tuning the electron-donating ability of 1,10-phenanthroline ligands

“…Additionally, compared to the previously reported neutral N-O and N-N chelating ligand-derived Ru(II) polypyridyl complexes, our phenanthroline-derived Ru(II) polypyridyl complexes with electron-donating groups not only improve the axial Cl activity, but also demonstrate improved aqueous solubility, making these Ru(II) complexes an excellent starting point for biological tests. 23,[53][54][55] DNA-binding studies DNA is the primary potential pharmacological target for many metallodrugs that are in use as anticancer agents, and distortions of the DNA structure are often associated with anticancer activity. Therefore, understanding DNA binding properties is an essential pathway for revealing the mechanism of anticancer agents.…”