Molecular two-point recognition of fructosyl valine and fructosyl glycyl histidine in water by fluorescent Zn(II)-terpyridine complexes bearing boronic acids.

التفاصيل البيبلوغرافية
العنوان:	Molecular two-point recognition of fructosyl valine and fructosyl glycyl histidine in water by fluorescent Zn(II)-terpyridine complexes bearing boronic acids.
المؤلفون:	Salomón-Flores, María K., Valdes-García, Josue, Viviano-Posadas, Alejandro O., Martínez-Otero, Diego, Barroso-Flores, Joaquín, Bazany-Rodríguez, Iván J., Dorazco-González, Alejandro
المصدر:	Dalton Transactions: An International Journal of Inorganic Chemistry; 5/28/2024, Vol. 53 Issue 20, p8692-8708, 17p
مصطلحات موضوعية:	MOLECULAR recognition, HISTIDINE, BORONIC acids, DIPYRRINS, PHOTOINDUCED electron transfer, BIOCHEMISTRY, VALINE
مستخلص:	Selective recognition of fructosyl amino acids in water by arylboronic acid-based receptors is a central field of modern supramolecular chemistry that impacts biological and medicinal chemistry. Fructosyl valine (FV) and fructosyl glycyl histidine (FGH) occur as N-terminal moieties of human glycated hemoglobin; therefore, the molecular design of biomimetic receptors is an attractive, but very challenging goal. Herein, we report three novel cationic Zn-terpyridine complexes bearing a fluorescent N-quinolinium nucleus covalently linked to three different isomers of strongly acidified phenylboronic acids (ortho-, 2Zn; meta-, 3Zn and para-, 4Zn) for the optical recognition of FV, FGH and comparative analytes (D -fructose, Gly, Val and His) in pure water at physiological pH. The complexes were designed to act as fluorescent receptors using a cooperative action of boric acid and a metal chelate. Complex 3Zn was found to display the most acidic –B(OH)2 group (pKa = 6.98) and exceptionally tight affinity for FV (K = 1.43 × 10⁵ M⁻¹) with a strong quenching analytical response in the micromolar concentration range. The addition of fructose and the other amino acids only induced moderate optical changes. On the basis of several spectroscopic tools (¹H, ¹¹B NMR, UV-Vis, and fluorescence titrations), ESI mass spectrometry, X-ray crystal structure, and DFT calculations, the interaction mode between 3Zn and FV is proposed in a 1 : 1 model through a cooperative two-point recognition involving a sp³ boronate–diol esterification with simultaneous coordination bonding of the carboxylate group of Val to the Zn atom. Fluorescence quenching is attributed to a static complexation photoinduced electron transfer mechanism as evidenced by lifetime experiments. The addition of FGH to 3Zn notably enhanced its emission intensity with micromolar affinity, but with a lower apparent binding constant than that observed for FV. FGH interacts with 3Zn through boronate–diol complexation and coordination of the imidazole ring of His. DFT-optimized structures of complexes 3Zn–FV and 3Zn–FGH show a picture of binding which shows that the Zn-complex has a suitable (B⋯Zn) distance to the two-point recognition with these analytes. Molecular recognition of fructosyl amino acids by transition-metal-based receptors has not been explored until now. [ABSTRACT FROM AUTHOR]
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قاعدة البيانات:	Complementary Index

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