title: The effect of phosphate on the nuclease activity of vanadium compounds.
abstract: The nuclease activity of VO(acac)2 (1, acac = acetylacetone) and its derivatives VO(hd)2 (2, hd = 3,5-heptanedione), VO(Cl-acac)2 (3, Cl-acac = 3-chloro-2,4-pentanedione), VO(Et-acac)2 (4, Et-acac = 3-ethyl-2,4-pentanedione) and VO(Me-acac)2 (5, Me-acac = 3-methyl-2,4-pentanedione), is studied by agarose gel electrophoresis, UV-visible spectroscopy, cyclic and square wave voltammetry and (51)V NMR. The mechanism is shown to be oxidative and associated with the formation of reactive oxygen species (ROS). Hydrolytic cleavage of the phosphodiester bond is also promoted by 1, but at much slower rate which cannot compete with the oxidative mechanism. The generation of ROS is much higher in the presence of phosphate buffer when compared with organic buffers and this was attributed to the formation of a mixed-ligand complex containing phosphate, (V(IV)O)(V(V)O)(acac)2(HnPO4(n-3)), presenting a quasi-reversible voltammetric behavior. The formation of this species was further observed by Electrospray Ionization Mass Spectrometry (ESI-MS). Phosphate being an essential species in most biological media, the importance of the formation of mixed-ligand species in other vanadium systems is emphasized.
authors.affiliation: Departamento de Química e Farmácia, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av Rovisco Pais, 1049-001 Lisboa, Portugal.
authors.forename: Nataliya
authors.initials: N
authors.lastname: Butenko
authors.affiliation: Departamento de Química e Farmácia, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
authors.forename: José Paulo
authors.initials: JP
authors.lastname: Pinheiro
authors.affiliation: Departamento de Química e Farmácia, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
authors.forename: José Paulo
authors.initials: JP
authors.lastname: Da Silva
authors.affiliation: Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av Rovisco Pais, 1049-001 Lisboa, Portugal; Faculdade de Ciências da Universidade de Lisboa, Campo Grande, Lisboa, Portugal.
authors.forename: Ana Isabel
authors.initials: AI
authors.lastname: Tomaz
authors.affiliation: Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av Rovisco Pais, 1049-001 Lisboa, Portugal.
authors.forename: Isabel
authors.initials: I
authors.lastname: Correia
authors.affiliation: Centro de Biomedicina Molecular e Estrutural, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
authors.forename: Vera
authors.initials: V
authors.lastname: Ribeiro
authors.affiliation: Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av Rovisco Pais, 1049-001 Lisboa, Portugal.
authors.forename: João
authors.initials: J
authors.lastname: Costa Pessoa
authors.affiliation: Departamento de Química e Farmácia, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av Rovisco Pais, 1049-001 Lisboa, Portugal. Electronic address: icavaco@ualg.pt.
authors.forename: Isabel
authors.initials: I
authors.lastname: Cavaco
mesh_terms: D004247:DNA / Q000737:chemistry*; D006868:Hydrolysis; D010084:Oxidation-Reduction; D010710:Phosphates / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000737:chemistry; D017968:Vanadium Compounds / Q000737:chemistry*
chemical_list: D010710:Phosphates; D017382:Reactive Oxygen Species; D017968:Vanadium Compounds; D004247:DNA
keywords: DNA cleavage; Inorganic nucleases; Oxidovanadium(IV/V) complexes; Phosphate; Vanadium acetylacetonate