Multiple spectroscopic and theoretical investigation of meso-tetra-(4-pyridyl)porphyrin‑ruthenium(II) complexes in HSA-binding studies. Effect of Zn(II) in protein binding

• Published in: Journal of molecular liquids 2019-11, Vol.294, p.111581, Article 111581
• Main Authors: Chaves, Otávio Augusto, Menezes, Lucas B., Iglesias, Bernardo A.
• Format: Article
• Language: English
• Subjects: HSA; Interaction; Porphyrins; Ru(II)
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2019.111581

The present work reports the interaction between human serum albumin (HSA) – the main bio-distributor of exogenous and endogenous compounds in the human bloodstream -and two synthetic Ru(II)-porphyrins (4-RuTPyP and 4-ZnRuTPyP), by multiple spectroscopic techniques (steady-state, time-resolved, circular dichroism, synchronous and 3D fluorescence) combined with molecular docking calculations. The interaction between HSA and each Ru(II) derivatives is spontaneous and moderate, being enthalpically and entropically driven. Steady-state and time-resolved fluorescence analysis showed static process as the main fluorescence quenching mechanism (ground-state association). The binding of tetra-ruthenated derivative containing Zn(II) ion caused more perturbation on the secondary structure of the albumin than the free-base porphyrin. Each Ru(II)-porphyrin interacts preferentially in the site III (subdomain IB), mainly via electrostatic and hydrophobic forces, as well as via van der Waals forces for the sample which contain Zn(II) ion. [Display omitted] •The interaction HSA:Ru(II)-porphyrin derivatives occurs via ground state association.•The interaction for all samples is moderate and thermodynamically favourable.•The 4-ZnRuTPyP can cause more perturbation on albumin structure than 4-RuTPyP.•Site III is the main binding pocket for all samples.•Overall, the presence of Zn(II) ion did not affect significantly its binding ability.