Speciation of Phytate Ion in Aqueous Solution. Thermodynamic Parameters for Zinc(II) Sequestration at Different Ionic Strengths and Temperatures

Crea, Francesco; Stefano, Concetta De; Milea, Demetrio; Sammartano, Silvio

doi:10.1007/s10953-008-9357-0

Cited by 31 publications

(32 citation statements)

References 38 publications

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“…Zinc-phytate has not previously been indicated in N. caerulescens, and its likely presence suggests a mechanism of Zn-tolerance whereby Zn is excluded from the symplasm. The large molecular size, great stability and resistance to enzymatic hydrolysis of Znphytate could hinder Zn transport across plasma membranes of root cells, preventing movement into the xylem and to the shoots (Angel et al 2002;Crea et al 2009;Van Steveninck et al 1994), and result in Zn accumulation in cell walls and apoplasm. The development of a method for sub-cellular in vivo XANES could further clarify the localization and speciation of Zn.…”

Section: Zinc Species In Rootsmentioning

confidence: 99%

In vivo speciation of zinc in Noccaea caerulescens in response to nitrogen form and zinc exposure

et al. 2011

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Nitrate has been shown to enhance Zn hyperaccumulation in the shoots of Noccaea caerulescens (formerly Thlaspi caerulescens) (Prayon); however, the mechanisms beyond the effect of nitrogen form are unknown. This study used synchrotron X-ray absorption near-edge spectroscopy (XANES) on alive and intact plants at room temperature to examine whether enhanced Zn hyperaccumulation in nitrate-fed plants was associated with differences in Zn speciation, and to correlate Zn species with mechanisms of Zn uptake, translocation and hyperaccumulation. The higher Zn concentration in plants supplied with nitrate compared to ammonium, or with high Zn exposure (300 μΜ), was not due to differences in Zn speciation. The importance of carboxylates for Zn hyperaccumulation in the shoots was supported by a predominance of Zn-malate or Zn-citrate. Zinc-phytate was detected for the first time in this species and may assist Zntolerance in the roots. The feasible presence of Znhistidine in the roots but not in the xylem sap suggests a mechanism for Zn binding and non-toxic transport through the cytoplasm and release of aqueous Zn into the xylem vessels. Zinc was translocated in the xylem as Zn-malate and weakly complexed or aqueous Zn forms. Zinc speciation in roots, shoots and xylem did not differ between nitrate-and ammonium-fed plants.

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Section: Zinc Species In Rootsmentioning

confidence: 99%

In vivo speciation of zinc in Noccaea caerulescens in response to nitrogen form and zinc exposure

et al. 2011

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“…The review aimed at identifying the most accurate data on phytate coordination in solution. Crea et al 36 investigated thermodynamic parameter for zinc(II) sequestration at different ionic strengths and temperatures. The sequestering ability of phytate toward zinc(II) was quantified in various conditions, and the dependence of these parameters on temperature, pH, and ionic strength was modeled by simple empirical equations.…”

Section: Introductionmentioning

confidence: 99%

Equilibrium, thermoanalytical and spectroscopic studies to characterize phytic acid complexes with Mn(II) and Co(II)

Carli¹,

Schnitzler²,

Ionashiro³

et al. 2009

J. Braz. Chem. Soc.

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Estudos potenciométricos foram realizados para determinar o grau de ligação do ácido fítico com os íons Co(II) e o Mn(II), na ausência de dioxigênio. As constantes de equilíbrio para as principais espécies formadas são relatadas, e os resultados são representados na forma de diagramas de distribuição mostrando a concentração individual dos complexos como uma função do pH. Os valores das constantes de formação dos complexos foram elevados para as espécies em que o ligante encontra-se mais desprotonado. Os dados potenciométricos indicam que a espécie [MH 4 L] 6-, encontra-se totalmente formada em pH 7,0 e a partir destes dados os complexos de Mn(II) e Co(II) com o ácido fítico foram sintetizados no estado sólido. Análises de infravermelho, termogravimetria e calorimetria exploratória diferencial foram utilizadas para caracterizar e investigar o comportamento térmico destes compostos. Os resultados conduziram a informações sobre composição, desidratação, estabilidade e decomposição térmica dos complexos. Potentiometric studies were carried out to determine the binding degree of phytic acid with Co(II) and Mn(II) ions, in the absence of dioxygen. Equilibrium constants for all major complexes formed are reported, and the results are presented in the form of distribution diagrams showing the concentrations of individual complexes as a function of pH. The formation constants of the complexes show higher values for the species in which the ligand was more deprotonated. Potentiometric data indicates that the species [MH 4 L] 6-, was totally formed at pH 7.0 and the complexes were synthesized from this data. A solid state complex of Mn(II) and Co(II) with phytic acid was synthesized. Thermogravimetry, differential scanning calorimetry, and infrared spectroscopy were used to investigate and characterize the thermal behavior of these compounds. The results led to information on the composition, dehydration, thermal stability and thermal decomposition of the isolated complexes.

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“…The main contribution to the formation of metal complexes with phytate is electrostatic and in fact the stability constants of the metal/ligand species increase with increasing the formal charge of the metal involved in the complex formation. The metal complex formation process is generally endothermic and the greater thermodynamic contribution to this process is entropic in nature [3,17,18]. Many endothermic processes are involved in the complex formation reaction, such as the neutralization of the charges and other processes involving water molecules.…”

Section: Introductionmentioning

confidence: 99%

“…Many endothermic processes are involved in the complex formation reaction, such as the neutralization of the charges and other processes involving water molecules. In a recent review and in successive works, the nature and the stability of many monovalent, divalent and trivalent metal/ligand systems, together with the interaction of phytate with polyammonium cations, xanthine and histamine has been deeply examined [1][2][3][4][18][19][20][21][22][23][24][25][26]. As an example, the importance of phytate lies in its ability to bind metal cations, in fact is has been demonstrated that phytate may have a neuroprotective effect in chelating iron [16]; in other studies it is reported that phytate presence in soy may decreases the manganese absorption [27].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics for proton binding of phytate in KNO3(aq) at different temperatures and ionic strengths

et al. 2013

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Speciation of Phytate Ion in Aqueous Solution. Thermodynamic Parameters for Zinc(II) Sequestration at Different Ionic Strengths and Temperatures

Cited by 31 publications

References 38 publications

In vivo speciation of zinc in Noccaea caerulescens in response to nitrogen form and zinc exposure

In vivo speciation of zinc in Noccaea caerulescens in response to nitrogen form and zinc exposure

Equilibrium, thermoanalytical and spectroscopic studies to characterize phytic acid complexes with Mn(II) and Co(II)

Thermodynamics for proton binding of phytate in KNO3(aq) at different temperatures and ionic strengths

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