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Título: | Complexes of Bifunctional DO3A-N-(α-amino)propinate Ligands with Mg(II), Ca(II), Cu(II), Zn(II), and Lanthanide(III) Ions: Thermodynamic Stability, Formation and Dissociation Kinetics, and Solution Dynamic NMR Studies | Autor: | Garda, Zoltán Kócs, Tamara Bányai, István Martins, José A. Kálmán, Ferenc Krisztián Tóth, Imre Geraldes, Carlos F. G. C. Tircsó, Gyula |
Palavras-chave: | Bifunctional ligands (BFCs); Complexes; Dynamic NMR; Equilibrium; Formation and dissociation kinetics | Data: | 16-Ago-2021 | Editora: | MDPI | Título da revista, periódico, livro ou evento: | Molecules | Volume: | 26 | Número: | 16 | Resumo: | The thermodynamic, kinetic, and structural properties of Ln3+ complexes with the bifunctional DO3A-ACE4- ligand and its amide derivative DO3A-BACE4- (modelling the case where DO3A-ACE4- ligand binds to vector molecules) have been studied in order to confirm the usefulness of the corresponding Gd3+ complexes as relaxation labels of targeted MRI contrast agents. The stability constants of the Mg2+ and Ca2+ complexes of DO3A-ACE4- and DO3A-BACE4- complexes are lower than for DOTA4- and DO3A3-, while the Zn2+ and Cu2+ complexes have similar and higher stability than for DOTA4- and DO3A3- complexes. The stability constants of the Ln(DO3A-BACE)- complexes increase from Ce3+ to Gd3+ but remain practically constant for the late Ln3+ ions (represented by Yb3+). The stability constants of the Ln(DO3A-ACE)4- and Ln(DO3A-BACE)4- complexes are several orders of magnitude lower than those of the corresponding DOTA4- and DO3A3- complexes. The formation rate of Eu(DO3A-ACE)- is one order of magnitude slower than for Eu(DOTA)-, due to the presence of the protonated amine group, which destabilizes the protonated intermediate complex. This protonated group causes the Ln(DO3A-ACE)- complexes to dissociate several orders of magnitude faster than Ln(DOTA)- and its absence in the Ln(DO3A-BACE)- complexes results in inertness similar to Ln(DOTA)- (as judged by the rate constants of acid assisted dissociation). The 1H NMR spectra of the diamagnetic Y(DO3A-ACE)- and Y(DO3A-BACE)- reflect the slow dynamics at low temperatures of the intramolecular isomerization process between the SA pair of enantiomers, R-Λ(λλλλ) and S-Δ(δδδδ). The conformation of the Cα-substituted pendant arm is different in the two complexes, where the bulky substituent is further away from the macrocyclic ring in Y(DO3A-BACE)- than the amino group in Y(DO3A-ACE)- to minimize steric hindrance. The temperature dependence of the spectra reflects slower ring motions than pendant arms rearrangements in both complexes. Although losing some thermodynamic stability relative to Gd(DOTA)-, Gd(DO3A-BACE)- is still quite inert, indicating the usefulness of the bifunctional DO3A-ACE4- in the design of GBCAs and Ln3+-based tags for protein structural NMR analysis. | URI: | https://hdl.handle.net/10316/95710 | ISSN: | 1420-3049 | DOI: | 10.3390/molecules26164956 | Direitos: | openAccess |
Aparece nas coleções: | I&D CIBIT - Artigos em Revistas Internacionais FCTUC Ciências da Vida - Artigos em Revistas Internacionais I&D CQC - Artigos em Revistas Internacionais |
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molecules-26-04956-v2.pdf | 30.73 MB | Adobe PDF | Ver/Abrir |
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