Equilibrium constants of metal amino acid complexes

Rey, F.; Antelo, Juan; Arce, F.; Penedo, Francisco J.

doi:10.1016/s0277-5387(00)80273-9

Cited by 22 publications

(14 citation statements)

References 8 publications

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“…This model is also supported by the low complex formation constants published for Ca 2+ -complexes with major silk constituents, e.g. glycine, alanine, tyrosine and serine [49].…”

Section: Discussionmentioning

confidence: 52%

Analysis of the Fibroin Solution State in Calcium Chloride/Water/Ethanol for Improved Understanding of the Regeneration Process

Ngo

Bechtold

2018

Fibres and Textiles in Eastern Europe

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Shaping of fibroin protein from Bombyx mori from calcium chloride/water/ethanol solution is of high interest for the manufacturing of biocompatible structures. Potentiometric titration experiments of the dissolved state permit new insight into the solution state of fibroin as a basis for improved regeneration. Titration experiments and infrared spectroscopy of the solution state support the model of an ion-rich hydration layer and interaction of the solvent with charged and polar groups of the fibroin, rather than through formation of defined calcium complexes. The potentiometric titration curves indicate the formation of calcium complexes at pH values above 9, most probably through involvement of basic amino acids and phenolic groups of tyrosine. After regeneration by the addition of methanol, the regenerated protein was characterised by FTIR, nitrogen and calcium analysis. The analysis of supernatants for their residual protein content indicated minor losses of protein, most probably low molecular weight proteins. The results contribute to an improved understanding of the solution state as a basis for larger scale regeneration, e.g. for the coating of textile fibres with regenerated fibroin.

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“…This model is also supported by the low complex formation constants published for Ca 2+ -complexes with major silk constituents, e.g. glycine, alanine, tyrosine and serine [49].…”

Section: Discussionmentioning

confidence: 52%

Analysis of the Fibroin Solution State in Calcium Chloride/Water/Ethanol for Improved Understanding of the Regeneration Process

Ngo

Bechtold

2018

Fibres and Textiles in Eastern Europe

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“…Therefore, based purely on ligand field theory, one predicts that the increase in T g for poly(L-histidine)/Cu 2ϩ complexes should be similar to ⌬T g for poly(L-histidine)/Ni 2ϩ complexes, as is the case for empirically determined hydration enthalpies 32 and lattice energies. 33 Solution equilibrium stability constants reported by Rey et al 18 for monomeric amino-acid-metal complexes also exhibit anomalous ordering with respect to the metal cations, as follows: Cd…”

Section: Qualitative Ligand Field Stabilization Analysis Of the Enhanmentioning

confidence: 96%

“…16 Nagase et al 17 has shown that Co 2ϩ , Ni 2ϩ , and Zn 2ϩ coordinate to amino acids that contain a thiazolidine ring. Rey et al 18 studied the complexation equilibria of L-serine and L-leucine with divalent cations of Mg, Ca, Co, Ni, Cu, Zn, Cd, and Pb in (1) aqueous ionic solutions and (2) , all other metal cations form both ML and ML 2 complexes. These results suggest that either pendant groups or coordination crosslinks should form when divalent metal ions are complexed with poly(amino acid)s. 19 While the solution properties of poly(␣-amino acid) complexes with metal ions have been examined, very little has been written about these systems in the solid state.…”

Section: Introductionmentioning

confidence: 99%

Solid-state complexes of poly(L-histidine) with metal chlorides from the first row of thed-block

McCurdie

Belfiore

1999

J. Polym. Sci. B Polym. Phys.

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Solid‐state characterization of poly(L‐histidine) was obtained via differential scanning calorimetry, thermogravimetric analysis, optical microscopy, and infrared spectroscopy. The glass transition temperature of poly(L‐histidine) is 169°C. This thermal transition has not been reported previously. Poly(L‐histidine)'s Tg increases when complexes are produced with the following divalent transition metal chlorides: cobalt chloride hexahydrate, nickel chloride hexahydrate, copper chloride dihydrate, and anhydrous zinc chloride. At 10 mol % salt, nickel chloride increases Tg by 69°C. The enhancement in poly(L‐histidine)'s Tg correlates well with ligand field stabilization energies for pseudo‐octahedral dn complexes (n = 7, 8, and 10) from the first row of the d‐block. However, d9 copper(II) complexes do not conform to this empirical correlation. Infrared spectroscopic evidence indicates that these metal chlorides form complexes with the imidazole ring in the histidine side group and the amide group in the main chain of the polymer. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 301–309, 1999

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“…Reliable data on the ionization constants of L leu cine [1][2][3][4][5][6][7][8][9][10][11][12][13] are available in literature. Those studies were carried out at different ionic strengths in different supporting electrolytes.…”

Section: Hl ± L -mentioning

confidence: 99%

“…Those studies were carried out at different ionic strengths in different supporting electrolytes. In order to perform correct comparison of the stepwise dissociation constants of L leucine reported by different authors, we calculated the рК 1 and рК 2 values for zero ionic strength using the Davies equation [14] (for I < 0.5): (3) and the equation (for I > 0.5) (4) where рК с and рК 0 are the negative logarithms of con centration and thermodynamic dissociation con stants; ΔZ 2 is the difference between squared charges of the reaction products and initial compounds; А is the Debye-Hückel limiting law constant, which is equal to 0.5107 at 25°С; δ is the empirical coefficient; and I is the ionic strength of solution.…”

Section: Hl ± L -mentioning

confidence: 99%