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Extent of Intramolecular [pi] Stacks in Aqueous Solution in Mixed-Ligand Copper(II) Complexes Formed by Heteroaromatic Amines and 1-[2-(Phosphonomethoxy)ethyl]cytosine (PMEC), a Relative of Antivirally Active Acyclic Nucleotide Analogues (Part 72)[1, 2]

Blindauer, Claudia A ; Sigel, Astrid ; Operschall, Bert P ; Holý, Antonin ; Sigel, Helmut

Zeitschrift für anorganische und allgemeine Chemie (1950), 2013-07, Vol.639 (8-9), p.1661 [Periódico revisado por pares]

Weinheim: Wiley Subscription Services, Inc

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  • Título:
    Extent of Intramolecular [pi] Stacks in Aqueous Solution in Mixed-Ligand Copper(II) Complexes Formed by Heteroaromatic Amines and 1-[2-(Phosphonomethoxy)ethyl]cytosine (PMEC), a Relative of Antivirally Active Acyclic Nucleotide Analogues (Part 72)[1, 2]
  • Autor: Blindauer, Claudia A ; Sigel, Astrid ; Operschall, Bert P ; Holý, Antonin ; Sigel, Helmut
  • Assuntos: Enzymes
  • É parte de: Zeitschrift für anorganische und allgemeine Chemie (1950), 2013-07, Vol.639 (8-9), p.1661
  • Descrição: Stability constants of the ternary Cu(Arm)(H;PMEC)+ and Cu(Arm)(PMEC) complexes {PMEC2- = dianion of 1-[2-(phosphonomethoxy)ethyl]cytosine, Arm = 2, 2'-bipyridine (Bpy) or 1, 10-phenanthroline (Phen)} were measured by potentiometric pH titrations (aq. sol.; 25 °C; I = 0.1 M, NaNO3) and compared with those of Cu(Arm)(H;PMEA)+ and Cu(Arm)(PMEA) {PMEA2- = dianion of 9-[2-(phosphonomethoxy)ethyl]adenine}, and related species. The basicity of the terminal phosphonate group is similar in PMEC2- and PMEA2-. Stability-constant comparisons reveal, that in the monoprotonated ternary Cu(Arm)(H;PMEC)+ complexes H+ is at the phosphonate group, that the ether oxygen atom of the -CH2-O-CH2-P(O)-2(OH) residue participates, next to the P(O)-2(OH) group, in Cu(Arm)2+ coordination, and that π-π stacking between the aromatic rings of Cu(Arm)2+ and the pyrimidine moiety is important. The Cu(Arm)(PMEC) complexes are considerably more stable than the corresponding Cu(Arm)(R-PO3) species, where R-PO2-3 is a phosph(on)ate with a group R unable to interact intramolecularly. The stability enhancements are mainly attributed to intramolecular stacks and, to a smaller extent, to the formation of five-membered chelates involving the ether oxygen atom of the -CH2-O-CH2-P(O)2-3 residue of PMEC2-. Analysis of the intramolecular equilibria reveals that ca. 10% of the isomeric ternary complexes exist with Cu(Arm)2+ solely coordinated to the phosphonate group, ca. 25% as a five-membered chelate involving the ether oxygen, and ca. 65% with an intramolecular π-π stack between the pyrimidine moiety of PMEC2- and the rings of Bpy or Phen. For a given Cu(Arm)2+ the stacking intensity increases from PMEC2- to PMEA2-. It seems feasible that the reduced stacking intensity of PMEC2-, together with a different hydrogen bonding pattern, leads to a different orientation of the cytosine residue (compared to the adenine moiety) in the active site of the nucleic acid polymerases, thus resulting in a reduced antiviral activity of PMEC compared to PMEA [PUBLICATION ABSTRACT].
  • Editor: Weinheim: Wiley Subscription Services, Inc
  • Idioma: Inglês;Alemão
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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