Evaluation of the Binding Constants, Bound Chemical Shifts, and Stoichiometry of Lanthanide–Substrate Complexes

1972 ◽  
Vol 50 (13) ◽  
pp. 2119-2129 ◽  
Author(s):  
Ian Armitage ◽  
G. Dunsmore ◽  
L. D. Hall ◽  
A. G. Marshall
Keyword(s):  
Chemical Shift ◽  
Chemical Shifts ◽  
Binding Constants ◽  
Shift Reagent ◽  
Accurate Solution ◽  
Conventional Procedure ◽  
Equilibrium Binding ◽  
Straight Line ◽  
Equilibrium Binding Constant ◽  
The Eu

A theoretical analysis of the equilibrium between a lanthanide shift reagent, L, and a substrate, S, is presented. When [Formula: see text] then a plot of [S]0vs. (1/δ) at constant [L]0 gives a straight line whose slope is [L]0ΔB and whose y-intercept is −{(1/KB) + [L]0}, where KB is the equilibrium binding constant, δ is the induced chemical shift, and ΔB is the bound chemical shift. A more general and accurate solution using a computer programme is applicable for all ratios of [L]0/[S]0. It is also shown that the conventional procedure for evaluating ΔB leads to varying values for ΔB that are generally too small, even under the most optimal conditions. Eu(DPM)34 has a KB of ca. 34.21 mol−1 with n-propylamine and KB of ca. 9.71 mol−1 with neo-pentanol. These values increase by at least 10-fold (to ≥ 1001 mol−1) for the corresponding complexes with Eu(FOD)34 shift reagent. However, the bound chemical shifts for the Eu(FOD)3 complexes are nearly the same as for the Eu(DPM)3 complexes. Finally, it is shown definitively that the association between Eu(DPM)3 and either n-propylamine or neo-pentanol has 1:1 stoichiometry; with Eu(FOD)3 a tentative assignment of 1:1 stoichiometry can be made.

scholarly journals Application of Lanthanide Shift Reagent to the 1H-NMR Assignments of Acridone Alkaloids

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5383
Author(s):  
Sio-Hong Lam ◽  
Hsin-Yi Hung ◽  
Ping-Chung Kuo ◽  
Daih-Huang Kuo ◽  
Fu-An Chen ◽  
...  
Keyword(s):  
Least Squares ◽  
Nmr Assignments ◽  
Least Squares Method ◽  
Chemical Shifts ◽  
Shift Reagent ◽  
Spectral Studies ◽  
Lanthanide Shift Reagent ◽  
Planar Structures ◽  
Acridone Alkaloids ◽  
The Eu

This study investigates the application of the paramagnetic shift reagent tris(dipivaloylmethanato)-europium(III) in NMR spectral studies of permethoxyacridone alkaloids (1–3) and pyranoacridone alkaloids (4–6). The induced chemical shifts (∆δ) of all protons were observed for the same molecule, and were compared to deduce the positions resulting from the distance nearby the Eu(dpm)3. Assignment of the H-2, H-4 and H-8 of polysubstituted acridones could be distinguished based on the least-squares method of lanthanide-induced shifts plotted against the mole ratios of Eu(dpm)3 to the substrate. The developed method is not only potentially useful for determining the planar structures of polysubstituted compounds, such as acridones, anthraquinones, xanthones, flavonoids, and phenanthrenes, but also applicable for their stereochemistry.

Association of a Europium Shift Reagent with Dialkylnitrosamines

1974 ◽  
Vol 52 (2) ◽  
pp. 315-324 ◽  
Author(s):  
Richard A. Perry ◽  
Yuan L. Chow
Keyword(s):  
Chemical Shifts ◽  
Equilibrium Constants ◽  
Molecular Geometry ◽  
Shift Reagent ◽  
Nitroso Group ◽  
Contact Shift ◽  
Substrate Ratio ◽  
The Eu

The Eu(fod)3 induced shifts of the n.m.r. signals of various nitrosamines were studied at a constant lanthanide concentration and also at constant nitrosamine concentration. The bound chemical shifts (ΔB) and binding equilibrium constants (K) were determined. The stoichiometry of the complexes appears to be 1:1 in CDCl3 in agreement with the criteria of two types of existing tests designed to determine Eu–substrate ratio. On the basis of the experimental ΔB values, the molecular geometry of Eu–nitrosamine complexes were computed according to the principle of pseudo-contact shift. It was concluded that the Eu atom complexed at the oxygen of the nitroso group and that the conformations of nitrosamines in the complexes were basically the same as those of uncomplexed nitrosamines.

scholarly journals Structure of Nanobody Nb23

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3567
Author(s):  
Mathias Percipalle ◽  
Yamanappa Hunashal ◽  
Jan Steyaert ◽  
Federico Fogolari ◽  
Gennaro Esposito
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Solution Structure ◽  
Chemical Shifts ◽  
Molecular Size ◽  
Side Chain ◽  
3D Nmr ◽  
Target Antigen ◽  
Internuclear Distances ◽  
2D And 3D

Background: Nanobodies, or VHHs, are derived from heavy chain-only antibodies (hcAbs) found in camelids. They overcome some of the inherent limitations of monoclonal antibodies (mAbs) and derivatives thereof, due to their smaller molecular size and higher stability, and thus present an alternative to mAbs for therapeutic use. Two nanobodies, Nb23 and Nb24, have been shown to similarly inhibit the self-aggregation of very amyloidogenic variants of β2-microglobulin. Here, the structure of Nb23 was modeled with the Chemical-Shift (CS)-Rosetta server using chemical shift assignments from nuclear magnetic resonance (NMR) spectroscopy experiments, and used as prior knowledge in PONDEROSA restrained modeling based on experimentally assessed internuclear distances. Further validation was comparatively obtained with the results of molecular dynamics trajectories calculated from the resulting best energy-minimized Nb23 conformers. Methods: 2D and 3D NMR spectroscopy experiments were carried out to determine the assignment of the backbone and side chain hydrogen, nitrogen and carbon resonances to extract chemical shifts and interproton separations for restrained modeling. Results: The solution structure of isolated Nb23 nanobody was determined. Conclusions: The structural analysis indicated that isolated Nb23 has a dynamic CDR3 loop distributed over different orientations with respect to Nb24, which could determine differences in target antigen affinity or complex lability.

Synthesis and structure of 2?-substituted 1-(1,3-dioxan-5-yl)uracils. Positive role of the Eu(fod)3 nmr shift reagent

1981 ◽  
Vol 17 (11) ◽  
pp. 1112-1119
Author(s):  
Yu. Yu. Samitov ◽  
I. N. Goncharova ◽  
N. P. Ramzaeva ◽  
A. F. Mishnev ◽  
Ya. Ya. Bleidelis
Keyword(s):  
Shift Reagent ◽  
Positive Role ◽  
Substituted 1 ◽  
The Eu

Circular dichroism spectra of tetraamminecobalt(III) complexes of amino alcohols

1978 ◽  
Vol 31 (11) ◽  
pp. 2399 ◽  
Author(s):  
CJ Hawkins ◽  
GA Lawrance ◽  
JA Palmer
Keyword(s):  
Circular Dichroism ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Amino Alcohols ◽  
Circular Dichroism Spectra ◽  
Chemical Shift Difference ◽  
Solvent Dependence ◽  
Cotton Effects ◽  
Circular Dichroïsm ◽  
Chiral Amino Alcohols

The circular dichroism spectra are reported for tetraamminecobalt(III) complexes with the chiral amino alcohols 2-aminopropan-1-ol, 2- aminobutan-1-ol, 1-aminopropan-2-ol, 2-amino-1-phenyl-ethanol, ψ- ephedrine and ephedrine with the alcohol groups protonated (OH) and deprotonated (O-). The solvent dependence of the chemical shifts of the NH protons was investigated to determine the effects of stereoselective solvation on the circular dichroism, but, in contrast to some other related systems, the chemical shift difference between the two NH2 protons was relatively insensitive to solvent. Consistent with this, the circular dichroism spectra of the tetraphenylborate salts of the deprotonated complexes were found not to be markedly dependent on solvent. Tetraammine-{(-)-ψ-ephedrine)cobalt(III) and tetraammine{(-)- ephedrine}cobalt(III) were found to have the same signs of Cotton effects for the various d-d transitions, whereas bis{(-)-ψ- ephedrine}copper(II) and bis{(-)-ephedrine}copper(II) had opposite signs. This has been explained in terms of different conformer populations in the cobalt(III) and copper(II) systems.

NMR studies of tandem WW domains of Nedd4 in complex with a PY motif-containing region of the epithelial sodium channel

1998 ◽  
Vol 76 (2-3) ◽  
pp. 341-350 ◽  
Author(s):  
Voula Kanelis ◽  
Neil A Farrow ◽  
Lewis E Kay ◽  
Daniela Rotin ◽  
Julie D Forman-Kay
Keyword(s):  
Chemical Shift ◽  
Sodium Channel ◽  
Chemical Shifts ◽  
Epithelial Sodium Channel ◽  
Chemical Shift Assignment ◽  
Nmr Studies ◽  
Ww Domains ◽  
Ww Ii ◽  
Py Motif ◽  
Shift Assignment

Nedd4 (neuronal precursor cell-expressed developmentally down-regulated 4) is a ubiquitin-protein ligase containing multiple WW domains. We have previously demonstrated the association between the WW domains of Nedd4 and PPxY (PY) motifs of the epithelial sodium channel (ENaC). In this paper, we report the assignment of backbone 1Hα, 1HN, 15N, 13C', 13Cα, and aliphatic 13C resonances of a fragment of rat Nedd4 (rNedd4) containing the two C-terminal WW domains, WW(II+III), complexed to a PY motif-containing peptide derived from the β subunit of rat ENaC, the βP2 peptide. The secondary structures of these two WW domains, determined from chemical shifts of 13Cα and 13Cβ resonances, are virtually identical to those of the WW domains of the Yes-associated protein YAP65 and the peptidyl-prolyl isomerase Pin1. Triple resonance experiments that detect the 1Hα chemical shift were necessary to complete the chemical shift assignment, owing to the large number of proline residues in this fragment of rNedd4. A new experiment, which correlates sequential residues via their 15N nuclei and also detects 1Hα chemical shifts, is introduced and its utility for the chemical shift assignment of sequential proline residues is discussed. Data collected on the WW(II+III)-βP2 complex indicate that these WW domains have different affinities for the βP2 peptide.Key words: WW domain, PY motif, Nedd4, ENaC, NMR.

Sign in / Sign up

Export Citation Format

Share Document