Interplay of crystallography, Raman microspectroscopy and electrospray mass spectrometry for studying the reaction between ruthenium complexes and proteins

Ruthenium complexes are evaluated as prospective pharmaceutical agents and have emerged as promising alternatives to Platinum compounds for anticancer chemotherapy. Due to the large interest of this class of compounds for bioinorganic chemistry and biomedical applications, it is demanding to investigate their reactivity with proteins. The reaction between NAMI-A and AziRu, two structurally related Ru(III) compounds with antitumor activity, and the model proteins hen egg white lysozyme, HEWL, and bovine pancreatic ribonuclease, RNase A, was investigated through electrospray ionization mass spectrometry, Raman microscopy, UV-visible absorption spectroscopy and X-ray crystallography [1-3]. In all cases, formation of stable metal-protein adducts was unambiguously demonstrated. Similarly, the product of the reaction between the paddle-wheel tetrakis(acetato)chlorido diruthenium(II,III) complex, [Ru2(µ-O2CCH3)4Cl], and HEWL has been characterized [4]. Taken together, the results of these works suggest that the combined used of X-ray crystallography, Raman microspectroscopy and electrospray mass spectrometry is a valuable tool for examining in detail the protein metalation process. [1] A. Vergara, G. D’Errico, D. Montesarchio, G. Mangiapia, L. Paduano, A. Merlino. Inorg Chem. 2013, 52(8):4157-9. [2] A. Vergara, D. Montesarchio, I. Russo Krauss, L. Paduano, A. Merlino. Inorg Chem 2013, 52(19):10714-10716. [3] L. Messori, A. Merlino. Dalton Trans 2014, 43, 6128-31.[4] L. Messori, T. Marzo, R. N. Fernandes Sanches, H.-U.-Rehman, D. de Oliveira Silva, A. Merlino. Angewandte Chemie Int. Ed. 2014, DOI: 10.1002/anie.201403337 and 10.1002/ange.20140333