Assessment of the Europium(III) Binding Sites on Albumin Using Fluorescence Spectroscopy

Abstract

Intrinsic fluorescence quenching of bovine serum albumin (BSA) and europium(III) luminescence in BSA complexes were investigated. The number of BSA binding sites (n) and equilibrium constant (Keq) values were determined from both measurements provided qualitatively different results. While the modified Stern-Volmer relation for BSA fluorescence quenching gave n = 1 at pH 4.5 and pH 6, two sets of binding sites were determined from Eu(3+) luminescence with n1 = 2, n2 = 4 at pH 6 and n1 = 1, n2 = 2 at pH 4.5. The model explaining the discrepancy between the results obtained by these fluorescent approaches was suggested, and the limitations in application of the "log-log" Stern-Volmer plots in analysis of binding processes were discussed.

Macroaggregated Albumin (MAA): Production, Size Optimization, Eu(III) and Tb(III) Complexes

“…Recently, some metal complexes bound to human serum albumin have shown high affinity toward DNA and have displayed various pharmacological properties (3). The development of metal complexes (especially Gallium, Gadolinium, and Lanthanides such as Europium and Terbium) that targeting cancerous cells under physiological conditions is of great current interest towards developing models for lots of pharmaceuticals from imaging and contrast agents to metal-based radionuclide and chemotherapeutics agents (2,(4)(5)(6). These agents are of considerable interest as magnetic resonance imaging (MRI) agents, bioresponsive cellular imaging agents, luminescent bioprobes, and also in targeted radionuclide therapy before clinical application as simulating agents (2).…”

Highly Sensitive and Reliable NIR Luminescent Sensing Toward Nitro‐Aromatic Antibiotics in Water

“…[ 31 ] The quenching constants were simulated and listed in Table 1 in terms of the Stern–Volmer (SV) equation of RI − 1 = K SV × [C], where RI was the relative intensity ( I 0 / I ) at certain wavelength, K SV was the quenching efficiency, and [C] was the concentration of titrated antibiotics. [ 32 ] On the basis of calculated K SV values, the limits of detection (LODs) could be determined according to the formula of 3σ/ K SV , where σ is the standard deviation for at least five repeated luminescent measurements for blank samples. [ 33 ] As a result, the LODs of the Yb‐dmh‐phen sensor toward NAA analytes ranged from 27 to 226 nM ( Table 1 ).…”

Supramolecular interaction of transition metal complexes with albumins and DNA: Spectroscopic methods of estimation of binding parameters

“…The method based on the protein fluorophore quenching is applied to study the interaction of protein molecules with different metal ions representing quenchers. [132][133][134][135] Quenching can also be used to identify the existence of protein tryptophan residues located both on the surface and in the inner region of the globule. [131] Thus, any drug introduced will interact to some extent with a macromolecule of albumin which determines essentially its biological accessibility and toxicity.…”