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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.
EN
Formation of Cd(II) and Hg(II) complexes in ternary systems with cytidine 5_-monophosphate (CMP) and diamines (en, tn, Put) has been studied. In Hg(II)/CMP/diamine systems the formation of heteroligand compounds is accompanied by the occurrence of non-covalent interactions and the formation of molecular complexes. The presence of polyamine in ternary systems does not change the metal-nucleotide mode of coordination. Similarly as in the binary Hg(II)/CMP system, the metallation involves the donor endocyclic nitrogen N(3) atom and CMP phosphate group. On the other hand, in the Cd(II)/CMP system, the introduction of a polyamine changes the coordination mode of the nucleotide. Phosphate group, inactive in binary systems, takes part in the complexation in ternary systems. In systems of cadmium(II) ions, CMP and diamines, only molecular complexes are formed, in which the polyamine is in the outer coordination sphere. In contrast to Cd(CMP)(H2tn) and Cd(CMP)(H2Put) compounds, in Cd(CMP)(H2en) species the phosphate group of nucleotide does not take part in the metallation, i.e. the metal ion coordinates with CMP, through the atom N(3) of the nucleotide, and the phosphate group is involved in non-covalent interactions with en.
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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