NMR Study on Lysophosphatidylcholine-Protein Interactions and Their Functional Properties
We analyzed the emulsion state of phospholipid-protein complexes from their dynamic structure. The interfacial adsorption of the complexes was evaluated by the mean droplet size of emulsions and NMR. The interfacial adsorptivity of ovalbumin (OA) was increased with the interaction of lysophosphatidylcholine (LPC) to form smaller droplets, and the formation of a fine emulsion was further promoted by the addition of linoleic acid in the mixture. The motional property of Ser-p68 of OA was much restricted at the interface when the complex formed a fine emulsion. The LPC changed the conformation of OA to increase the α-helix and to reduce the β-sheet content by interaction with the protein, and the heat stability of the protein was enhanced. The results of .31P and 13C NMR spectrum indicated that LPC is bound to OA through hydrophobic interaction and lead to conformational change of protein structure. These results suggested that LPC and linoleic acid mutually changed the structure of protein to increase the interfacial adsorption and heat stability. The region of Ser-p68 in OA was tightly adsorbed at the interface when the complexes formed fine emulsion.
KeywordsLinoleic Acid Droplet Size Nuclear Magnetic Resonance Spectrum Aqueous Dispersion Interfacial Adsorptivity
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