The reaction between the paddle-wheel tetrakis(acetato)chloridodiruthenium(II,III) complex, [Ru2(μ-O2CCH3)4Cl] and hen egg-white lysozyme (HEWL) was investigated through ESI-MS and UV/Vis spectroscopy and the formation of a stable metal-protein adduct was unambiguously demonstrated. Remarkably, the diruthenium core is conserved in the adduct while two of the four acetate ligands are released. The crystal structure of this diruthenium-protein derivative was subsequently solved through X-ray diffraction analysis to 2.1 Å resolution. The structural data are in agreement with the solution results. It was found that HEWL binds two diruthenium moieties, at Asp101 and Asp119, respectively, with the concomitant release of two acetate ligands from each diruthenium center.

§These authors have contributed equally to this work. Diruthenium paddlewheel structured complexes bearing a Ru 2 (II,III) multiply bonded core show promising potential in medicinal chemistry. This work reports studies on the interactions of the tetrakis(acetato)chloridodiruthenium(II,III) complex (RuAc), [Ru 2 (μ-O 2 CH 3 ) 4 Cl], and the corresponding Ru 2 (II,III)-NSAID metallodrugs of the non-steroidal anti-inflammatory drugs (NSAIDs) ibuprofen (RuIbp) and ketoprofen (RuKet) with the human serum albumin (HSA).Circular dichroism studies showed that the three Ru 2 complexes interact with the HSA and induce conformational changes on the secondary structure of the protein. The reaction of the RuAc complex with the protein was monitored and the RuAc-HSA binding constant was estimated on the basis of electronic absorption spectroscopy data. Fluorescence emission spectroscopy studies were performed for all the Ru 2 complex/HSA systems and the SternVolmer constants and the thermodynamic parameters were determined for the RuAc-HSA binding. Mass spectrometry data confirmed the presence of the Ru 2 complexes in the protein phase after ultrafiltration. The studies suggest that the nature of the RuAc binding to the HSA is 2 distinct from that of the derived RuIbp and RuKet metallodrugs. Electrostatic forces, accompanied by coordination of the metal to the amino acid side chains of the protein, seem to be the main forces acting in the RuAc/HSA binding, while non-covalent/hydrophobic forces might be predominant in the protein-(Ru 2 -NSAID metallodrug) interactions. The findings suggest that the HSA protein might be a potential carrier in the blood plasma for the Ru 2 (II,III)-NSAID metallodrugs.

The reaction between the paddle-wheel tetrakis-(acetato)chloridodiruthenium (II,III) complex, [Ru 2 (m-O 2 CCH 3 ) 4 Cl] and hen egg-white lysozyme (HEWL) was investigated through ESI-MS and UV/Vis spectroscopy and the formation of a stable metal-protein adduct was unambiguously demonstrated. Remarkably, the diruthenium core is conserved in the adduct while two of the four acetate ligands are released. The crystal structure of this diruthenium-protein derivative was subsequently solved through X-ray diffraction analysis to 2.1 resolution. The structural data are in agreement with the solution results. It was found that HEWL binds two diruthenium moieties, at Asp101 and Asp119, respectively, with the concomitant release of two acetate ligands from each diruthenium center.

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Primeiramente agradeço à Prof. Dra. Denise de Oliveira Silva, minha orientadora, que me recebeu tão bem no grupo, e que dedicou tanto do seu tempo e atenção, e que foi mais que orientadora. Pela compreensão, pela confiança, pelo incentivo, por acreditar no meu potencial, e por contribuir enormemente para o meu desenvolvimento profissional e pessoal. Muito obrigada.