Equilibrium study on the interaction of phytic acid with polyamines and metal ions

Abstract

Interaction of phytic acid (myo-inositolhexakisphosphoric acid, IP) and polyamines (A = en, tn, Put, dien, 2,3-tri, 3,3-tri, Spd, 3,3,3-tet, spermine(Spm)) have been studied by potentiometric and (31)P-NMR techniques. The non-covalent interactions have led to the formation of stable molecular complexes of (IP)H(n)(A) type at the 1:1 molar ratio of the ligands, but of different numbers of protons. The IP protonation constants, stability constants of the molecular complexes and metal (Mg(2+)) complexes have been determined. The structural and pH dependences of stability constants showed the interactions between IP and A have the acid-base character determining their effectiveness, although the IP structure (5ax1eq, 5eq1ax) in molecular complexes should be also taken into account. (31)P NMR study showed in the presence of Spm (31)P highfield shifts and high pH shift of signal broadening due to chemical exchange between 5ax1eq and 5eq1ax. The preferable binding of Spm to IP over Mg(2+) in neutral pH indicated the importance of polyamine as a stabilizer of phosphate compounds.

Interaction of myo-inositol hexakisphosphate with biogenic and synthetic polyamines

“…35 For put, cad, spd and spm, various studies were previously carried out, even though none of them was performed under the same experimental conditions. 29,30,35,58 A similar behaviourthat is, a decrease in protonation constant values − is found for Me 2 hexaen, Me 2 heptaen and Me 2 octaen in 0.15 M Me 4 NCl at 37.0°C with respect to previous values obtained at 25.0°C in 0.15 M NaClO 4 solutions, 32 in agreement with the exothermicity of the protonation processes involving these polyamines. Almost all other previous protonation constants were measured at 20 or 25°C.…”

“…It has been shown that, in similar complexes, protonation is governed by the different basicity of the interacting species. 30 Table 2). † For all the studied systems, the complexes detected have a 1 : 1 amine : InsP 6 molar ratio in different protonation states.…”

“…1), is an ubiquitous and abundant molecule in eukaryotic cells. [29][30][31] Nevertheless, the possibility that this interaction might influence the in vivo speciation of InsP 6 is still unexplored; the high concentration of biogenic amines, normally found in vivo in high excess relative to the InsP 6 , makes it worth testing. The high charge displayed by InsP 6 species under simulated physiological conditions (H 4 L 8− being the main species) implies that strong electrostatic interactions occur with metal cations (M) sharing the same environments.…”

Phosphorus fractionation and protein content control chemical phosphorus removal from corn biorefinery streams

“…In the LSF experiments, the TP concentration decreased by 23% when solution pH was increased from 4.5 to 8 (Figure ). Because P i concentration decreased by only 11% after pH adjustment, the observed removal was attributed to phytate precipitation with either Mg or K, which were both highly concentrated in LSF (Table ) (Nolan, Duffin, & McWeeny, ; Odani, Jastrzab, & Lomozik, ). Although phytate concentrations were not directly measured, it was assumed that, as the major P o species in LSF and TSF, most P o removal was associated with the corresponding phytate removal.…”

On the interaction of phytate with proton and monocharged inorganic cations in different ionic media, and modeling of acid-base properties at low ionic strength

“…Phytic acid takes place in many physiological reactions, and its use in many fields is continuously growing, mainly thanks to its binding ability towards many metal and organo-metal cations, as well as other ligands [1][2][3][4][5][6]. These properties, together with many other possible use of phytate (e.g., in electrochemistry), are well described in many books and papers (e.g., [7][8][9][10][11][12][13][14][15][16][17][18] and references therein).…”