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Evaluation of the binding of four anti-tumor Casiopeinas to human serum albumin

Publication . Correia, Isabel; Borovic, Sladjana; Cavaco, Isabel; Matos, Cristina P.; Roy, Somnath; Santos, Hugo M.; Fernandes, Luz; Capelo, Jose L.; Ruiz-Azuara, Lena; Pessoa, Joao Costa

The metal complexes designated by Casiopeinas (R) are mixed-ligand Cu-II-compounds some of them having promising antineoplastic properties. We report studies of binding of Cu(glycinato)(4,7-dimethyl-1,10-phenanthroline) (Cas-II-Gly (1)), Cu(acetylacetonato)(4,7-dimethy1-1,10-phenanthroline) (Cas-III-Ea (2)), Cu(glycinato) (4,4'-dimethyl-2,2'-bipyridine) (Cas-W-Gly (3)) and Cu(acetylacetonato)(4,4'-dimethyl-2,2'-bipyridine) (Cas-IIIia (4)) to human serum albumin (HSA) by circular dichroism (CD), Electron paramagnetic resonance (EPR) and fluorescence spectroscopy. The results indicate that HSA may bind up to three molecules of the tested Casiopeinas. This is confirmed by inductively coupled plasma atomic absorption spectroscopy measurements of samples of HSA-Casiopeinas after passing by adequate size-exclusion columns. The binding of Cas-II-Gly to HSA was also confirmed by MALDI-TOF mass spectrometric experiments. In the physiological range of concentrations the Casiopeinas form 1:1 adducts with HSA, with conditional binding constants of ca. 1 x 10(9) (1), 4 x 10(7) (2), 1 x 10(6) (3) and 2 x 10(5) (4), values determined from the CD spectra measured, and the fluorescence emission spectra indicates that the binding takes place close to the Trp214 residue. Overall, the data confirm that these Casiopeinas may bind to HSA and may be transported in blood serum by this protein; this might allow some selective tumor targeting, particularly in the case of Cas-Il-Gly. In this work we also discuss aspects associated to the reliability of the frequently used methodologies to determine binding constants based on the measurement of fluorescence emission spectra of solutions containing low concentrations of proteins such as HSA and BSA, by titration with solutions of metal complexes.

2017-10Journal article

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Combined proteomic and metallomic analyses in Scrobicularia plana clams to assess environmental pollution of estuarine ecosystems

Publication . Gonzalez-Dominguez, Raúl; Santos, Hugo Miguel; Bebianno, Maria João; Garcia-Barrera, Tamara; Gomez-Ariza, José Luis; Capelo, José Luis

Estuaries are very important ecosystems with great ecological and economic value, but usually highly impacted by anthropogenic pressure. Thus, the assessment of pollution levels in these habitats is critical in order to evaluate their environmental quality. In this work, we combined complementary metallomic and proteomic approaches with the aim to monitor the effects of environmental pollution on Scrobicularia piano clams captured in three estuarine systems from the south coast of Portugal; Arade estuary, Ria Formosa and Guadiana estuary. Multi-elemental profiling of digestive glands was carried out to evaluate the differential pollution levels in the three study areas. Then, proteomic analysis by means of two-dimensional gel electrophoresis and mass spectrometry revealed twenty-one differential proteins, which could be associated with multiple toxicological mechanisms induced in environmentally stressed organisms. Accordingly, it could be concluded that the combination of different omic approaches presents a great potential in environmental research. (C) 2016 Elsevier Ltd. All rights reserved.

2016-12Journal article

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