Carbon-13 NMR study of the synergistic anion in transferrins

Bertini, Ivano; Luchinat, Claudio; Messori, Luigi; Scozzafava, A.; Pellacani, Giancarlo; Sola, Marcó

doi:10.1021/ic00231a013

Cited by 41 publications

(28 citation statements)

References 11 publications

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“…A similar stoichiometry of Ti:hTF 1.9( AE 0.1):1 was obtained from the measurement of the titanium content of purified titanium transferrin by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The value of the extinction coefficient for the first step of Ti IV binding to transferrin (occupation of one lobe), De 1 , is 17 000 AE 400 m À1 cm À1 at 241 nm, which is the same as the value determined for Ti [11,12] d 166.8/167.2 for Sc III , [13] and d 165.8 for Bi III ). [14] Even though The apparently strong binding of Ti IV ions to transferrin is consistent with predictions based on metal ion acidity: the most acidic metal ions bind the most strongly.…”

supporting

confidence: 69%

The First Specific TiIV-Protein Complex: Potential Relevance to Anticancer Activity of Titanocenes

Sun

Weir

et al. 1998

Angewandte Chemie International Edition

117

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supporting

confidence: 69%

The First Specific TiIV-Protein Complex: Potential Relevance to Anticancer Activity of Titanocenes

Sun

Weir

et al. 1998

Angewandte Chemie International Edition

117

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“…When the first mol equiv of Zr(NTA) 2 2-was added, a new, sharp peak at 167.4 ppm appeared, which is assignable to bound 13 CO 3 2-. The chemical shift is similar to those reported previously for other metal-hTF adducts, for example, 165.8 ppm for Bi(III) and 166.5 ppm for Ga(III) and Ti(IV) [11,18,39] and to that for Zr(EDTA)(CO 3 ) (vide supra). The intensity of this peak increased upon the addition of the second mol equiv of Zr(NTA) 2 2-.…”

Section: Displacement Of Fe(iii) Fromsupporting

confidence: 87%

“…The sharp peak at 160.9 ppm corresponds to unbound H 13 CO 3 -and the broad envelope at 170-180 ppm to carbonyl groups of the backbone and side-chains of hTF (natural abundance 13 C) [18,39]. When the first mol equiv of Zr(NTA) 2 2-was added, a new, sharp peak at 167.4 ppm appeared, which is assignable to bound 13 CO 3 2-.…”

Section: Displacement Of Fe(iii) Frommentioning

confidence: 98%

“…This value is unreasonably high and also does not take account of hydrolysed forms of Zr(IV) and carbonate binding to Zr(EDTA). The 13 C NMR spectrum of Zr(EDTA) at pH* 7.4 in the presence of 2 mol equiv of H 13 CO 3 -contained two peaks at 167.2 ppm and 160.6 ppm, assignable to bound 13 CO 3 2-and free -, respectively [11,18,39]. In the presence of 0.2 mol equiv H 13 CO 3 -, only the peak at 167.2 ppm corresponding to bound 13 CO 3 2-was detected.…”

Section: Rate and Stoichiometry Of Zr(iv) Binding To Apo-htfmentioning

confidence: 99%

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Unusual features for zirconium(IV) binding to human serum transferrin

et al. 2002

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Human serum apotransferrin (hTF) binds to Zr(IV) slowly in the presence of nitrilotriacetate (NTA), citrate or ethylenediaminetetraacetate (EDTA) as donor ligands. For Zr(NTA)(2)(2-) as donor, equilibrium was reached in ca. 2 h (pH 7.4, 298 K, 10 mM Hepes, 5 mM bicarbonate) and full loading of the N- and C-lobe sites was achievable to give Zr(2)-hTF. (13)C NMR data suggest that carbonate can bind as a synergistic anion. (1)H and 2D [(1)H,(13)C] (using epsilon-[(13)C]Met-hTF) NMR studies show that there is little lobe-selectively in the order of Zr(IV) uptake. Fe(III) displaced Zr(IV) from the C-lobe of Zr(2)-hTF first, followed by the N-lobe. However, in the presence of a large excess of NTA, Zr(IV) binds to the N-lobe of holo-hTF (Fe(2)-hTF) first followed by the C-lobe. The (1)H and (13)C NMR chemical shift changes for epsilon-[(13)CH(3)] of Met464, which is close to the C-lobe site, are quite distinct from those observed previously for Al(III), Fe(III), Ti(IV), Ga(III) and Bi(III) binding to hTF, suggesting that Zr(IV) binding may not induce lobe closure [as observed previously for Hf(IV)]. This may affect receptor recognition and play a role in the different biological behaviour of Zr(IV) compared to Ti(IV).

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“…This 1,2-bidentate metal coordination is as predicted from electron-spin echo envelope modulation (ESEEM) studies (Dubach, Gaffney, More, Eaton & Eaton, 1991) and suggests that the predictions of similar bidentate coordination for other anions will prove to be correct. The observed differences in chemical shifts for the two carboxylate groups, seen in NMR studies of oxalatesubstituted transferrins (Bertini et al, 1986), must be due to their different environments with respect to their interactions with the protein.…”

Section: Discussionmentioning

confidence: 98%

Structure of copper- and oxalate-substituted human lactoferrin at 2.0 Å resolution

Smith¹,

Anderson²,

Baker³

et al. 1994

Acta Cryst D

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The three-dimensional structure of human dicupric monooxalate lactoferrin, Cu2oxLf, has been determined to 2.0 A resolution, using X-ray diffraction data collected by diffractometry to 2.5 A resolution, and oscillation photography on a synchrotron source to 2.0A resolution. Difference electrondensity maps calculated between Cu2oxLf and both dicupric lactoferrin, Cu2Lf, and diferric lactoferrin, Fe2Lf, showed that the oxalate had replaced a carbonate in the C-terminal binding site, and that, relative to Cu2Lf, there were no significant differences in the N-terminal site. The structure was then refined crystallographically by restrained leastsquares methods. The final model, in which the r.m.s. deviation in bond distances is 0.017 A, contains 5314 protein atoms (691 residues), two Cu 2~ ions, one bicarbonate ion, one oxalate ion, 325 solvent molecules and one sugar residue. The crystallographic R factor of 0.193 is for 46 134 reflections in the range 8.0 to 2.0 A resolution. The oxalate ion is coordinated to copper in a 1,2-bidentate fashion, and the added bulk of the anion results in the rearrangement of the side chains of nearby arginine and tyrosine residues. No other major alterations in the molecule can be observed, the overall protein structure being the same as that for Cu2Lf and Fe2Lf.

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Carbon-13 NMR study of the synergistic anion in transferrins

Cited by 41 publications

References 11 publications

The First Specific TiIV-Protein Complex: Potential Relevance to Anticancer Activity of Titanocenes

The First Specific TiIV-Protein Complex: Potential Relevance to Anticancer Activity of Titanocenes

Unusual features for zirconium(IV) binding to human serum transferrin

Structure of copper- and oxalate-substituted human lactoferrin at 2.0 Å resolution

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