Friesen, Sergej and Kruchinin, Sergey E. and Fedotova, Marina V. and Buchner, Richard (2024) Cation-Binding of Glutamate in Aqueous Solution. JOURNAL OF PHYSICAL CHEMISTRY B, 128 (23). pp. 5746-5755. ISSN 1520-6106, 1520-5207
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Interactions of the cations Li+, Na+, Mg2+, and Ca2+ with L-glutamate (Glu(-)) in aqueous solution were studied at room temperature with dielectric relaxation spectroscopy in the gigahertz region. Spectra of similar to 0.4 M NaGlu with added LiCl, NaCl, MgCl2, or CaCl2 (c(MCln) <= 1.5 M) were evaluated and experiments supplemented by density functional theory and 3D reference interaction site model (3D-RISM) calculations. In addition to the modes found for aqueous NaGlu, namely, the reorientation of free Glu(-) ions (peaking at similar to 1.6 GHz), of moderately retarded H2O molecules hydrating the carboxylate moieties of Glu(-) (similar to 8.4 GHz), of the cooperative resettling of the H-bond network of bulk water (similar to 20 GHz), and its preceding fast H-bond flip (similar to 400 GHz), an additional low-frequency relaxation at similar to 0.4 GHz was detected upon the addition of the four salts. In the case of NaGlu + MgCl2(aq) and NaGlu + CaCl2(aq), this mode could be unequivocally assigned to an ion pair formed by the cation and the side-chain carboxylate moiety of Glu(-). For NaGlu + LiCl(aq), either this species or a backbone-[Li+-H2O-Cl--Glu(-)] triple ion is formed. Binding constants increase in the order Li+<Mg2+<Ca2+. For NaGlu + NaCl(aq), an assignment of the similar to 0.4 GHz mode to ion pairs or triples was not plausible. Accordingly, its origin remains speculative here.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | ION HYDRATION; AMINO-ACIDS; WATER; DYNAMICS; ASSOCIATION; RELAXATION; DESIGN; ORIGIN; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry VI - Physical Chemistry (Solution Chemistry) > PD Dr. Richard Buchner |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 07 Oct 2025 06:27 |
| Last Modified: | 07 Oct 2025 06:27 |
| URI: | https://pred.uni-regensburg.de/id/eprint/64247 |
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