Study of binary and ternary complexes of copper(II) with some polyamines and adenosine 5? triphosphate Jacqueline Alves da Silva a , Judith Felcman a, *, Ana Lucia Ramalho Merce ˆ b , Antonio Sa ´lvio Mangrich b , Rosa ˆngela S.C. Lopes c , Cla ´udio Cerqueira Lopes c a Department of Chemistry, Pontifı ´cia Universidade Cato ´lica do Rio de Janeiro (PUC-Rio), R. Marque ˆs de S. Vicente, 225 Ga ´ vea 22453-900 Rio de Janeiro, RJ, Brazil b Department of Chemistry, Universidade Federal do Parana ´ (UFPR), Curitiba, Brazil c Department of Analytical Chemistry, Institute of Chemistry, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil Received 3 March 2003; accepted 20 June 2003 This article is dedicated to Professor Joa ˜o J.R. Frau ´sto da Silva Abstract The binary and ternary systems of Cu(II) complexes with adenosine 5? triphosphate (ATP) and the polyamines (PA): ethylenediamine (en), 1,3-diaminopropane (tn), spermidine (Spd) and bis-[(2S )-2-pyrrolidinylmethyl]ethylenediamine (tetraamine) were investigated. The study was performed in aqueous solution using potentiometry, ultraviolet visible and EPR spectroscopies. The stability constants of the complexes were determined by potentiometry (T /25 8C, m /0.1 mol l 1 , KNO 3 ). The order of the values of the stability constants of the ternary complexes was CutetraamineATP !/CuSpdATP !/CuenATP !/CutnATP and it is the same of the correspondent binary complexes of Cu(II) with these polyamines. This behavior was confirmed by the increasing of the maximum wavelength of the absorption spectra and the g 0 parameter of the EPR analyses and by the decreasing of the A 0 parameter as the stability constants decrease. D log K (log b CuPAATP /(log b CuPA  /log b CuATP ) showed that the ternary complexes are less stable than the binary ones, suggesting that it does not occur any interaction between the ligands in the ternary complexes. When the same calculation was done for the protonated species CuH q PAATP, the stability constants of the complexes were greater. When PA /Spd or tetraamine This result showed that these protonated ligands favored more stable ternary complexes, though only CuHSpdATP exists in pH :/7. # 2003 Elsevier B.V. All rights reserved. Keywords: Polyamines; Ternary complexes; Polyamine  /phosphate interactions; Stability constants; EPR parameters 1. Introduction Natural polyamines (PA) such as putrescine (Put, NH 2 (CH 2 ) 4 NH 2 ), spermidine (Spd, NH 2 (CH 2 ) 3 NH(CH 2 ) 4 NH 2 ) and spermine (Spm, NH 2 (CH 2 ) 3 NH(CH 2 ) 4 NH(CH 2 ) 3 NH 2 ), are found in most living organisms and are involved in many biological reactions, in particular, in metallation reac- tions, where they act as substrates for hormone synthesis [1  /3] and react with nucleic acid, leading to structural changes in the latter. These reactions determine the role of PA in processes of genetic information transfer [2  /4]. It has been observed that natural polyamines occur relatively at high concentrations in young cells, includ- ing cancer cells [5]. In physiological pH ( :/7), these polyamines are found in the protonated cation form. Due to their protonated-NH 3  groups, and mainly in this form, they interact with negatively charged fragments of other bioligands such as fragments of amino acids, proteins, fatty acids, phospholipids, nucleotides and nucleic acids [1]. The polyamine  /bioligand interactions are observed in the range of pH in which the polyamine is protonated while the bioligand is deprotonated. The tendency towards formation of molecular complexes depends * Corresponding author. Tel.:  /55-21-3114 1329; fax:  /55-21-3114 1637. E-mail address: felcman@rdc.puc-rio.br (J. Felcman). Inorganica Chimica Acta 356 (2003) 155  /166 www.elsevier.com/locate/ica 0020-1693/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0020-1693(03)00462-6