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Complexes of Copper(II) with 1,2-Diaminopropane and 2-Methyl-1,2-diaminopropane

Łomozik L., Krzyśko G., Gąsowska A., Bregier-Jarzębowska R.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 11

2221-2225

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Efektywność grup donorowych nukleotydów w reakcjach z jonami metali w układach podwójnych i potrójnych z udziałem tetramin

Gąsowska A.

Wiadomości Chemiczne

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2007

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[Z] 61, 5-6

339-359

EN

Nucleotides, being multifunctional ligands with donor nitrogen and oxygen atoms, take part in the majority of selective and specific processes occurring in nature [1-15]. It has been established that nucleotides react with the polyamines (biogenic amines) present in the living organisms and take part in genetic information transfer [16-24]. Nucleotides are composed of a purine or pyrimidine base, sugar residua and phosphate groups (Fig. 1) [25-27]. Each of the three components have potential centres of interaction with metal ions [28-29]. Because of the wide diversity of coordination possibilities there are often controversies as to the mode of coordination even in simple complexes with metal ions. Some authors claim that only nitrogen atoms of the nucleotide are effectively engaged in the metallation [30-43], while others maintain that it requires a combined engagement of nitrogen atoms and phosphate group [44-71]. There are also researchers who point to the involvement of only phosphate group of the nucleotide in the metallation [72-77]. The reaction of nucleotides with tetramines results in the formation of molecular complexes (Fig. 3) [78-88]. In the literature to date, there is no agreement as to the character of interactions and effectiveness of nucleotide donor groups in the formation of adducts with polyamines [80-82, 85-87, 89, 90]. According to some authors, the interaction between a nucleotide and polyamines in the metal-free systems has a noncovalent ion-ion or ion-dipole nature and the stability of molecular complexes is determined by the number of active centres in the reagents and the structural factor [80-84, 87]. According to other authors, it is a typical electrostatic interaction and the adduct stability is determined by the charge of the reagents [85, 89]. In the adducts formed by nucleotides with polyamines, the main interaction centres of a nucleotide are endocyclic nitrogen atoms and a phosphate group (the latter undergoes deprotonation already at a low pH), while in the case of tetramine the interaction centres are the NHx+ groups [77, 80-87, 89-91]. In the ternary systems of metal/nucleotide/tetramine, the following heteroligand molecular complexes are formed: MLźźźźźźHxL' (x = 4, HxL'-fully protonated polyamine) (Fig. 4) [80-82, 91, 94, 96], mixed protonated complexes MLHxL' (x = 1, 2, 3) (Fig. 5) [81, 82, 92, 96] and MLL' type complexes (Fig. 6) [81, 82, 91]. A significant influence of polyamines on the character of interactions of nucleotides with metal ions has been noted [80-82, 90-96]. In molecular complexes, the fully protonated polyamine is located in the outer coordination sphere. In the MLHxL' type complexes, the deprotonated nitrogen atoms of tetramine are involved in the coordination, while its protonated centres -NHx+ take part in noncovalent interactions that additionally stabilise the complex [81, 82, 92, 96, 97]. In the MLL' type complexes, oxygen atoms of nucleotide phosphate group and deprotonated nitrogen atoms of tetramine are in the inner coordination sphere, while nucleotide donor nitrogen atoms do not take part in the metallation [81, 82, 91].

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Reactions of Complexation of Co(II), Ni(II), Cu(II), Cd(II) and Hg(II) Ions with Adenosine 5'-Diphosphate

Łomozik L., Gąsowska A., Bregier-Jarzębowska R.

Polish Journal of Chemistry

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2004

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Vol.78 /nr 11-12

2023-2035

EN

The reaction of complexation has been studied in the systems of the ions: Co(II), Ni(II), Cu(II), Cd(II) and Hg(II) with adenosine 5_-diphosphate. The composition and stability constants of the complexes formed have been determined by the potentiometric method. The presence of the species type: MHL, MLx, and MLOH has been confirmed and their mode of coordination has been identified on the basis of the spectral data. In the acidic solution, the coordination dichotomy N(1)/N(7) has been found in all systems studied. At pH above 7, the dichotomy does not occur in the systems with Cu(II), while in the systems with Hg(II) only phosphate groups are involved in metallation. In the synthesized solid complexes of Cd(II) with AMPor ADP, the metal ion is bound by the donor nitrogen atom N(1), and in the complexes with ATP by the nitrogen atom N(7) of the nucleotide. Moreover, in the species with adenosine di- and triphosphate, the oxygen atoms of the phosphate groups are engaged in the complexation, while in the species Cd(AMP), similarly as in the liquid phase, the phosphate group is not involved in metallation.

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Interaction Centers of Purine and Pyrimidine Nucleotides in Their Reactions with Cu(II), Ni(II), Co(II), Cd(II) and Hg(II) Ions

Gąsowska A., Bregier-Jarzębowska R., Łomozik L.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 6

773-783

EN

It has been established that in ATP complexes with Cu(II), Co(II) and Cd(II) ions, the metallation centres are the oxygen atoms of the phosphate group and the nitrogen atom N(7) from the purine ring. The spectral data suggest some involvement of N(1) atom in these interactions. In the ATP complexes with Ni(II) the main centres of coordination were found to be N(7) and N(1), while the contribution of the oxygen atoms from the phosphate group is of secondary importance. In the ATP complexes with Hg(II) ions, above pH 7, the metallation involves only the oxygen atoms from the phosphate group, while the N(1) and N(7) atoms are outside the inner sphere of coordination. In the complexes of CTP with the metal ions studied the interaction centres are the oxygen atoms from the phosphate group and N(3) from the pyrimidine ring. However, in the case of complexes with Ni(II), the main centre of interaction is N(3), while the involvement of the oxygen atoms from the phosphate group is of minor importance.

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Jony metali jako czynnik ingerujący w oddziaływaniach poliamin z fragmentami kwasów nukleinowych

Łomozik L., Gąsowska A.

Wiadomości Chemiczne

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2000

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[Z] 54, 1-2

87--103

EN

Structurally simple aliphatic polyamines: putrescine (Put), spermidine (Spd) and spermine (Spm) occur in the cells of living organisms (human, animals, plants and bacteria) in relatively high concentrations. These compounds participate in many living processes [1-4 and references therein]. High basicity of polyamines implies that in the physiological conditions they appear in the protonated form and thus can interact with the negative fragments of other biomolecules. According to the polyelectrolytic theory of Manning, structural changes of particular molecules in interactions with the other components of the system depend mainly on the charge of the reagents, however, this approach does not explain a high specificity of certain reactions. It has been recently suggested that apart from the charge, also the polycation structure seems to play an important role. Computer analysis of the potentiometric titration data allowed a determination of the stability constants of molecular complexes formed by polyamines and fragments of the nucleic acids. Analysis of the titration and the spectral data indicates that at least two active centers are needed to obtain a relatively stable adduct. The thesis saying that the main sites of interactions are the protonated amine groups from PA and the negative or high electron density fragments of nucleosides or nucleotides (ion-dipole or ion-ion interactions) has been confirmed by the pH ranges of the molecular complexes occurrence. In nucleosides and nucleotides the main sites of metallation are the donor endocyclic N(3) atoms from the pyrimidine ring and N(1) or N(7) atoms from the purine ring. Phosphate groups of nucleotides are also effective centers of reaction. Polyamines change the character of the coordination dichotomy (mixture of isomers with the N(1) or N(7) coordination) observed in the metal-nucleoside (or nucleotide) systems. In general, with increasing length of the polyamine, the tendency to formation of heteroligand mixed complexes decreases and, interestingly, this tendency is exactly the opposite to that of formation of molecular complexes Nuc/PA. Already small changes in the polyamine length significantly affect their complex formation properties and reactions with metal ions or molecules in living cells. This explains the differences in the properties of biogenic amines and their biologically inactive homologues. In the ternary systems Cu/Nuc/Spm and Cu/NMP/Spm some interesting differences were observed in the coordination mode of the complexes. In the complex Cu(Nuc)(Spm) the metal ion was found to coordinate four nitrogen atoms from the polyamine in the equatorial plane and the N(3) or N(7) atom at the axial position (coordination structure of the square pyramid). In the system with the nucleotide, Cu(II) binds the phosphate group, while the polyamine is involved in non-covalent interaction with the donor nitrogen atoms from the purine or pyrimidine base and forms an adduct with intermolecular non-covalent complex-ligand interactions. In the systems with nucleosides, copper ions inhibit the interactions of adenosine or cytidine with polyamines. On the other hand, spermine involved in the non-covalent interaction with a nucleotide base blocks the potential metallation sites of AMP or CMP, changing essentially the character of coordination. Considering the role of the complexation processes in the above model systems, it should be added that formation of PA complexes with metal ions and fragments of nucleic acids is a factor ensuring homeostasis of polyamines in living cells. Reduction of the effect of diamine oxidase on the amines involved in the complexation processes increases their lifetime in living organisms.

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Solution structure of Cu(II) complexes with spermine and nucleosides or nucleotides in ternary systems

Gąsowska A., Łomozik L., Brieger-Jarzębowska R.

Polish Journal of Chemistry

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1999

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vol. 73 nr 6

909-913

EN

The mode of coordination of the complexes formed in the systems Cu/spermine/nucleoside (or nucleotide) was proposed on the basis of the equilibrium and spectral studies. Significant differences were found in the coordination character of nucleosides and nucleotides. In the systems with adenosine or cytidine, mixed-ligand complexes are formed with the N5 type coordination. On the other hand, in the systems with their monophosphates, molecular complexes are formed with metal ions coordinated through monophosphates, molecular complexes are formed with metal ions coordinated through oxygen atoms from the phosphate groups. Spermine, left outside the inner coordination sphere, is involved in non-covalent interactions with nitrogen atoms from the nucleotide bases.

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Cobalt(II), nickel(II) and copper(II) complexes with adenosine 5'-monophosphate and cytidine 5'-monophosphate in aqueous solutions and in solids

Gąsowska A., Łomozik L.

Polish Journal of Chemistry

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1999

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vol. 73 nr 3

465-474

EN

Determination of stability constants and calculation of distribution of complexes formed by Co(II), Ni(II) and Cu(II) with adenosine monophosphate (AMP) and cytidine monophosphate (CMP) were performed by using computer -aided analysis of potentiometric titration data. On the basis of the comparison of the protonation constants of free ligands and MHL-type complexes the proton localization in the coordination compounds was established. The coordination mode in complexes in solution as well as in solids was determined from the results of spectral as well as equilibrium studies. Formation of macrochelate complexes and the occurrence of coordination dichotomy of the N(1)N(7) type as well as N(1)N(7)/O (phosphate group) was evidenced. Contrary to the similar complexes with Cu(II) and Co(II), the phosphate group of the nucleotide becomes essentially involved in the interactions with Ni(II) ions only at high pH values. The modes of coordination in aqueous solution and solid complexes are compared.