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

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

“…Protonated polyamine Spm (amine groups are positive reaction centers) as well as phosphoserine (−COO − group and −PO 4 2− are negative reaction centers) are involved in noncovalent interaction with the CuATP parent species. The suggested mode of noncovalent interaction between the coordinated ATP and spermine as well as between CuATP and Ser-P was also recently described in [29,43]. Similar values of λ max and g || as well as A || for CuH 5 (ATP)(Ser-P) (Spm) and CuH 6 (ATP)(Ser-P)(Spm), Table 2, and no changes in the Raman and CD spectra of both complexes, together with similar chemical shifts in the NMR spectra, indicate the same mode of coordination in these two species, (Tables 3, 4).…”

“…1) are: the endocyclic nitrogen atoms N(1) or N(7) of adenine ring and the phosphate groups in ATP, the carboxyl, phosphate and amine groups in Ser-P and two terminal amine groups as well as two secondary amine groups in Spm [38][39][40][41][42]. These groups are also potential sites of noncovalent interactions as we have recently found in many similar systems [43][44][45]. Model selection (including stoichiometric composition and stability constants) was done using potentiometric method.…”

“…The information from spectral observations was supported by NMR investigation. 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 were interpreted taking into account the limitations of this method following from the presence of paramagnetic ions in the systems studied [32,43,44]. In order to minimize the NMR signal broadening, the spectra were recorded for very low concentrations of the metal.…”

“…Addition of excessive amount of spermine to the ternary Cu/ATP/ Ser-P system where {1 N,O x } chromophore has been found [43] results in significant change in the d-d band location. The difference in the d-d band positions (of about 120 nm) points to three nitrogen atoms of ligands involved in coordination in the CuH 3 (ATP)(Ser-P) (Spm) complex predominant in the 1:1:1:10 system.…”

Potentiometric determination of novel complexes of selected lanthanide ions with N,N’-bis(5-methylsalicylidene)-4-methyl-1,3-phenylenediamine

“…The results were scrutinized to eliminate the species that were rejected in the refinement procedures. The criteria used for verification of results are given in an earlier paper [34,35].…”