Conformational changes of bovine serum albumin upon its adsorption in dodecane-in-water emulsions as revealed by front-face steady-state fluorescence.
Front-face fluorescence spectroscopy was used to characterise dodecane-in-buffer (0.1 M phosphate buffer; pH = 7.6) emulsions stabilised by bovine serum albumin (BSA). A 15-nm blue-shift of the emission maximum of the adsorbed protein and a significant increase of its fluorescence quantum yield were observed. The contribution of tyrosyl residues to total fluorescence was tentatively evaluated from different spectra and an R ratio taking into account the stray-light interference; R increased upon BSA absorption but the Tyrosine contribution remained weak in all cases. Thus, conformational changes of the protein take place upon BSA adsorption onto the dodecane-water interface. They involve modifications in the environment of the protein aromatic amino acids especially of the tryptophanyl residues which are displaced to a more hydrophobic location. Moreover, the proportions of absorbed and non-adsorbed BSA in emulsions can be estimated from the position of the emission maximum.
Castelain
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Institut National de la Recherche Agronomique, Laboratoire d'Etude des Interactions des Molécules Alimentaires, Nantes, France.
Genot
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D000327:Adsorption; D000473:Alkanes; D000818:Animals; D002417:Cattle; D004655:Emulsions; D011487:Protein Conformation; D012709:Serum Albumin / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D014443:Tyrosine; D014867:Water
D000473:Alkanes; D004655:Emulsions; D012709:Serum Albumin; D014867:Water; C007548:n-dodecane; D014443:Tyrosine