Interactions of histone amino acid: lysine with copper(II) ions and adenosine 5′-triphosphate as well as in a metal-free system

Abstract

Thermodynamic stability and mode of coordination were studied in the binary system of copper(II)/ lysine, ternary system of copper(II)/ATP/lysine, and compared to the intermolecular interaction in the metal-free ATP/lysine system. In the system ATP/Lys, groups P β and P γ from ATP, participate in the interaction with the amino acid, while group P α from ATP is involved as reaction center only at high pH. The endocyclic nitrogens from the nucleotide N(1) and N(7) take part in the interactions only below physiological pH. In the binary complexes, oxygens from carboxylic group and nitrogen from the α-NH 2 amino group are involved in coordination. However, introduction of the second ligand, ATP, into the system Cu(II)/Lys changes the amino acid coordination in alkaline medium. In protonated mixed-ligand complexes, the α, β, and γ oxygens of the phosphate from ATP coordinate, but at higher pH, only α oxygens coordinate in Cu(ATP)(Lys). Although Cu(II) ions do not coordinate nitrogen from ATP in the ternary system, the presence of metal ions excludes interaction of these atoms over the whole pH range studied.

L‐argininato copper(II) complexes in solution exert significant selective anticancer and antimicrobial activities

“…The value of d-d transition for the Cu(L-Arg) complex, λ max =680 nm (Figure 3a), taken at pH=5.0, indicates the involvement in the metalation of solely one nitrogen atom and oxygen atoms from carboxyl group, which suggests a glycine-like coordination ({N,O x } chromophore). [53,54] A binding of a second L-Arg molecule results in Cu(L-Arg) 2 species whose equilibrium constant is logK e =6.61. This value is slightly lower than logK e =7.55 for Cu(L-Arg) species (Table 1), due to the influence of steric hindrance on the binding of the second L-Arg.…”

“…Cu(L-Arg) 2 (phen) 18.39 (9) 3.40 (Figure 3a), which corresponds to involvement of another nitrogen in Cu(II) coordination. An analysis of the equilibrium constants (logK e ) and spectral data revealed that in the Cu(L-Arg) 2 species the coordination involves two nitrogen atoms from both L-Arginine molecules (besides the oxygens), i.e., two glycine-like NO coordinated ligands (chromophore {N 2 ,O x }, where besides the two ligands an oxygen and unidentified number of water oxygens are bound), similarly to the corresponding complexes with glycine [45] or lysine [53,54] and in agreement with EPR results (see 3.2.3).…”

“…The ESI-MS spectra were measured in positive mode for both copper(II) complexes ( Figures S1 and S2 2.052 [56] 2.240 [56] 188 [56] 2.238 [33] 191 [33] [Cu(phen)] 2+ 2.067 (pH = 5.0) [53] 2.310 (pH=5.0) [56] 162 [56] (A) 2.318 (pH=7.0) [33] 168 [33] (B) 2.260 (pH=7.0) [33] 169 [33] Identified our results, in general, are consistent with those obtained by Gatlin and coworkers [35] who investigated quantitatively in situ-formed ternary complexes of Cu 2+ and phen with the 20 essential amino acids using electrospray ionization (ESI) mass spectra. The number of forms strongly depends on the complex concentration, solvent type and measurement conditions, which was proven by Gatlin.…”