Potentiometric and spectroscopic study of mixed copper(II) complexes with amino acids and either adenosine 5′ triphosphate or phosphocreatine

Heteronuclear complexes of phosphocreatine with copper(II) and magnesium(II) ions

“…Although the protonation constants as well as stability constants of copper and magnesium complexes can be found in literature, they were refined in this paper in the same experimental condition and are consistent with the literature data [30][31][32][33]. The values of successive protonation constants: logK 1 = 10.14, logK 2 = 4.94 determined for PCr from the computer analysis of titration data correspond to the protonation of the guanidine group and the second site at the phosphate group, respectively.…”

Phosphoserine and specific types of its coordination in copper(II) and adenosine nucleotides systems – Potentiometric and spectroscopic studies

“…The same mode of phosphoserine coordination was observed in the complex Cu(Ser-P)(ADP) and in the binary system Cu/Ser-P at high pH where the phosphate group was inactive [25]. Also, according to [35], in the system Cu/ATP/Ser at pH above 7, serine coordinates via the amine group and ATP only via phosphate groups (k max = 704.2 nm).…”

“…The changes in the chemical shift in the 13 C NMR spectrum of the ATP C(5) and C(8) atoms by À0.41 ppm and À0.48 ppm, respectively, imply that the copper ion has been attached to N(7) from ATP. On the other hand, the changes in the electron density on N(1) (C(2) 0.57 ppm and C(6) 0.51 ppm) in this pH are a result of weak interactions of HN(1) from ATP with Ser-P. For the Cu/ATP/ Ser system described by de Moraes et al (the lack of a phosphate group acting as a negative interaction centre in the amino acid) no non-covalent bonds were found between the ligands [35]. The Table 3.…”

“…In Ser-P the sites of metal coordination are the carboxyl, phosphate and amine groups. When oxygen atoms (not originating from water molecules) are replaced by nitrogen ones in the tetragonal geometry in cupric ion, the maximum absorption wavelength shifts to smaller values, indicating an appearance of a stronger ligand field, and the molar absorptivity usually increases (k max for {3N} coordination it is 600 nm, for {4N} 550 nm and for {3N1O} k max is 584 nm) [35,36]. The information was supported by the analysis of the chemical shifts in the 13 C and 31 P NMR spectra of the ligand in the complex with respect to those of the free ligand, interpreted according to our experience and taking into account the limitations of this method following from the presence of paramagnetic ions in the systems studied [37][38][39][40].…”

The effect of spermine concentration on the solution structure of complexes formed in copper(II)/adenosine 5′-triphosphate/phosphoserine system

“…EPR parameter values as well as the position of d-d transition (g || = 2.24 and A || = 185 × 10 −4 cm −1 , λ max = 650 nm, Table 2) point to {2 N, O x } chromophore formation, as it can be concluded taking into consideration the convincing results of observation of similar systems, for which the relation between the spectral parameters and the type of coordination has been established [48][49][50][51]. Moreover, in order to determine the particular sites of metal bonding in this multicomponent system, several spectral techniques were applied.…”