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Abstract

This paper briefly presents a review concerning the species which can arise when iron salts and citric acid are mixed together. The data commented on are required for a correct interpretation of the chemical processes which play a paramount role in biology and in the biological studies involving iron-citrate complexes.

Reduction of Fe(III) Ions Complexed to Physiological Ligands by Lipoyl Dehydrogenase and Other Flavoenzymes in Vitro

“…The reported binding stoichiometries for ATP, ADP, and citrate to Fe(III) show a surprising variation, ranging from 1:2 (55) to 1:6 (56) for Fe(III)-ATP and from 1:1 to 1:4 for the Fe(III)-citrate complex, for example (57). Consequently, the binding stoichiometries and thus the chemical characteristics of the Fe(III) complexes under the present experimental conditions are undefined.…”

“…ent on the characteristics of the chelating ligand (12,25,40 (25,40,55,57,73,74). Therefore, kinetic properties of the lipoyl dehydrogenase-mediated Fe(III) reduction and NAD(P)H oxidation can be assessed only in the absence of oxygen (see below).…”

Characterization of the citrate precursor, used for synthesis of nanosized Mg-Zn ferrites

“…The frequency shift of the IR-active bands, with respect to the theoretical positions from 3150 to 3213 cm -1 and from1400 to 1437 cm -1 were assigned to formation of hydrogen bonds in the sample "Precursor" with NH 4 + participation [15]. The formation of citrate complexes is proven by the doublets located at 1617 and 1578 cm -1 due to antisymmetric stretching vibration, and at 1415 and 1399 cm -1 due to symmetrical stretching vibration of ionized carboxylate groups [5,6,10,13]. The band positions are close to the ones cited in the analogous citrate precursors for ferrites, which are listed in Table 1.…”

“…The two bands at 524 and 480 cm -1 were assigned to Zn-O and Mg-O bonds [16,17]. The most common coordination for d 10 cations of Zn is tetrahedral and they mainly form covalent bonds with ligands [18]. For the d° cations of Mg, interactions with ligands are predominantly columbic or ionic, however, the tetrahedral geometry is also characteristic of their complexes [18].…”

“…According to the dissociation scheme of citric acid [9,10], at a pH rate of about 6 -, where M=Zn(II) and Mg(II). The coordination chemistry of citric acid -Fe(III) system is studied taking into account the biological importance only [10][11][12]. The established results in contributed to the better elucidation of the complex formation between Fe(III) and citric acid.…”