Characterization of the emulsification properties of 2S albumins from sunflower seed.
The ability of 2S albumins from sunflower seeds to stabilize oil-in-water emulsions has been investigated, demonstrating that one of the proteins (SFA8) effectively stabilizes emulsions, while another (SF-LTP) does not stabilize emulsions. The surface tension and surface dilation viscosity of these two proteins were measured, rationalizing the emulsifying ability of SFA8 in terms of its ability to form a strongly elastic monolayer at interfaces. The secondary structure changes that occur upon adsorption of SFA8 to the oil/water interface have also been studied by fluorescence, circular dichroism (CD), and Fourier-transform infrared (FT-IR) spectroscopy. It was found that the beta-sheet content of the protein increased upon adsorption at the expense of alpha-helix and random structure. Moreover, FT-IR measurements indicate the presence of intermolecular beta-sheet formation upon adsorption. Fluorescence studies with an oil-soluble fluorescence quencher indicate that the single tryptophan residue present in SFA8 may become located in the oil-phase of the emulsion. This residue is thought to be partially buried in the native protein, and these data suggest that changes in the polypeptide region flanking this residue may play an important role in the molecular rearrangement that occur on or following adsorption to the oil/water interface.
Burnett
Gary R
GR
Institute of Food Research, Norwich Research Park, Colney Lane, Norwich, NR4 7UA, United Kingdom. gary.burnett@bbsrc.ac.uk
Rigby
Neil M
NM
Mills
E N Clare
EN
Belton
Peter S
PS
Fido
Roger J
RJ
Tatham
Arthur S
AS
Shewry
Peter R
PR
D000327:Adsorption; D000418:Albumins / Q000737:chemistry* / Q000302:isolation & purification; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D045703:Emulsifying Agents / Q000737:chemistry*; D006368:Helianthus / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D017433:Protein Structure, Secondary; D012639:Seeds / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D017550:Spectroscopy, Fourier Transform Infrared; D013500:Surface Tension; D014783:Viscosity
D000418:Albumins; D045703:Emulsifying Agents