Nuclear magnetic resonance study of the conformation and dynamics of beta-casein at the oil/water interface in emulsions.

AUTOR(ES)

ter Beek, L C

RESUMO

A (13)C and (31)P nuclear magnetic resonance (NMR) study has been carried out on beta-casein adsorbed at the interface of a tetradecane/water emulsion. (13)C NMR spectra show signals from the carbonyl, carboxyl, aromatic, and C alpha carbons in beta-casein, well resolved from solvent resonances. Only a small fraction of all carbon atoms in beta-casein contribute to detectable signals; intensity measurements show that the observable spectrum is derived from about 30 to 40 amino acid residues.(31)P NMR spectra show signals from the five phosphoserines on the hydrophilic N-terminal part of the protein. Analysis of T(1) relaxation times of these nuclei, using the model free approach for the spectral density function and the line shape of the alpha-carbon region, indicates that a large part of the protein is in a random coil conformation with restricted motion and a relatively long internal correlation time. The NMR results show that the conformation and dynamics of the N-terminal part of beta-casein are not strongly altered at the oil/water interface, as compared to beta-casein in micelle-like aggregates in aqueous solution.

Documentos Relacionados

• Analysis of Composite Membranes in the Separation of Emulsions Sunflower oil/water
• Macroscopic interface self-motion of an oil/water liquid membrane
• Morphology of soy protein isolate at oil/water and oil/air interfaces
• beta-Casein mRNA sequesters a single-stranded nucleic acid-binding protein which negatively regulates the beta-casein gene promoter.
• Tissue-specific expression of the rat beta-casein gene in transgenic mice.