Carboxylate Ion Pairing with Alkali-Metal Ions for ß-Lactoglobulin and Its Role on Aggregation and Interfacial Adsorption.
J Phys Chem B
; 119(17): 5505-17, 2015 Apr 30.
Article
em En
| MEDLINE
| ID: mdl-25825918
ABSTRACT
We report a combined experimental and computational study of the whey protein ß-lactoglobulin (BLG) in different electrolyte solutions. Vibrational sum-frequency generation (SFG) and ellipsometry were used to investigate the molecular structure of BLG modified air-water interfaces as a function of LiCl, NaCl, and KCl concentrations. Molecular dynamics (MD) simulations and thermodynamic integration provided details of the ion pairing of protein surface residues with alkali-metal cations. Our results at pH 6.2 indicate that BLG at the air-water interface forms mono- and bilayers preferably at low and high ionic strength, respectively. Results from SFG spectroscopy and ellipsometry are consistent with intimate ion pairing of alkali-metal cations with aspartate and glutamate carboxylates, which is shown to be more effective for smaller cations (Li(+) and Na(+)). MD simulations show not only carboxylate-alkali-metal ion pairs but also ion multiplets with the alkali-metal ion in a bridging position between two or more carboxylates. Consequently, alkali-metal cations can bridge carboxylates not only within a monomer but also between monomers, thus providing an important dimerization mechanism between hydrophilic surface patches.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Compostos Organometálicos
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Ácidos Carboxílicos
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Multimerização Proteica
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Lactoglobulinas
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Metais Alcalinos
Idioma:
En
Revista:
J Phys Chem B
Assunto da revista:
QUIMICA
Ano de publicação:
2015
Tipo de documento:
Article
País de afiliação:
Alemanha