Reactivity of Ni II , Pd II and Pt II complexes bearing phosphine ligands towards Zn II displacement and hydrolysis in Cis 2 His 2 and Cis 3 His zinc-fingers domains.

A systematic study of the effect of phosphine and bis-phosphine ligands in the interaction of Ni ^II , Pd ^II , and Pt ^II complexes with two classes of zinc fingers was performed. The Cys ₂ His ₂ , finger 3 of specific protein-1, and the Cys ₂ HisCys C-terminal zinc finger of nucleocapsid protein 7 of the HIV-1 were used as models of the respective class. In general, phosphine ligands favor the metal binding to the peptide, although the bis-phosphine ligands produce more specific binding than the monodentate. In the case of nickel complexes, the interaction of Ni ^II ions with the sequence SKH, present in Cys ₂ His ₂ , results in hydrolysis, contrasting to the preferred zinc ejection produced by the Ni ^II complexes with chelating phosphines, producing Ni(bis-phosphine) fingers. In the absence of the SKH sequence, zinc ejection is observed with the formation of nickel fingers, with reactivity dependent on the phosphine. On the other hand, Pd(phosphines) produces Pd ₂ fingers in the case of triphenylphosphine with the phosphine coordinated as intermediate species. The bis-phosphine ligands produce very clean spectra and a stable signal Pd(bis-phosphine)finger. Interestingly, phosphines produce very reactive platinum complexes, which eject zinc and promote peptide hydrolysis. The results reported here are relevant to the understanding of the mechanism of these interactions and how to modulate metallocompounds for zinc finger interference.
Competing Interests: Declaration of Competing Interest The authors declare no conflicts of interest.
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