title: To be dinuclear or not: Z-DNA induction by nickel complexes.
abstract: The left-handed Z-DNA has been identified as a gene regulating element. Therefore the generation of Z-DNA through metal complexes might be an innovative way for the regulation of gene expression. Use of the new dinuclear complex N,N,N',N'-tetrakis-[2-(3,5-dimethylpyrazol-1-yl)ethyl]-1,3-propylenediamine-bis(nickel(II) dinitrate) (2) reversibly induced Z-DNA formation. However, when a 1:1 ratio of metal/dinucleating ligand was used as a control, the midpoint of the B- to Z-DNA transition was at the same nickel concentration as in case of the dinuclear complex. The novel mononuclear analogue, N-methyl-N,N-bis-[2-(3,5-dimethylpyrazol-1-yl)ethyl]amine-nickel(II)-dinitrate (3) was inducing the Z-DNA at a similar ratio versus nucleotides as free nickel(II) itself. For the first time, proton and nickel binding constants for the bis-[2-(pyrazol-1-yl)ethyl]amine ligand system are reported and discussed. Both nickel complexes 2 and 3 were structurally characterized by single crystal analysis. Furthermore, the synthesis of the two new ligands, N,N,N',N'-tetrakis-[2-(3,5-dimethylpyrazol-1-yl)ethyl]-1,2-propylenediamine (4) and N-methyl-N,N-bis-[2-(3,5-dimethylpyrazol-1-yl)ethyl]amine (5) is described. The two major synthetic pathways leading to polypyrazoyl amines in general are critically discussed with respect to yield, reproducibility and handling of the intermediates.
authors.affiliation: University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland. spingler@aci.unizh.ch
authors.forename: Bernhard
authors.initials: B
authors.lastname: Spingler
authors.forename: Philipp M
authors.initials: PM
authors.lastname: Antoni
mesh_terms: D043542:DNA, Z-Form / Q000737:chemistry*; D005021:Ethylamines / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry*; D011720:Pyrazoles / Q000737:chemistry*
chemical_list: D043542:DNA, Z-Form; D005021:Ethylamines; D011720:Pyrazoles; D009532:Nickel