Identification of salivary proteins at oil-water interfaces stabilized by lysozyme and beta-lactoglobulin.
In this research, we investigated the interaction occurring between oil-in-water emulsion droplets, stabilized by different emulsifiers, i.e. lysozyme and beta-lactoglobulin (beta-lg), and salivary proteins (SPs) with a molecular mass (M(r)) above about 10kDa. Different techniques, i.e. infrared spectroscopy, Western blotting, PAS staining and SDS-PAGE coupled to MS, were employed for this purpose. This study demonstrated the interaction between several salivary proteins and the emulsifiers at the oil-water interfaces. In particular, results show that the high M(r) mucin MUC5B was strongly bound to lysozyme stabilized emulsions, whereas beta-lg stabilized emulsions associated with MUC7 and, moderately, with MUC5B. Furthermore, we observed that salivary proteins in the range M(r) 10-100kDa associated differently with emulsion droplets. A large majority of SPs was found to interact with lysozyme stabilized emulsion droplets whilst in case of beta-lg stabilized emulsions, the SPs distribute more evenly between the fraction associated and non-associated with the droplets. A clear example is alpha-amylase (M(r) approximately 55kDa) which predominantly associates with lysozyme stabilized emulsion droplets, but not with beta-lg emulsion droplets. To conclude, our findings indicate that adsorption/association of salivary protein components onto the emulsion droplets is related to the type of emulsifying proteins at the oil-water interfaces and it is probably driven by the overall net charge at the droplet's oil-water interfaces, i.e. positive for lysozyme stabilized emulsions and negative for beta-lactoglobulin stabilized emulsion at neutral pH.
Silletti
Erika
E
Top Institute Food and Nutrition PO Box 557, 6700 AN Wageningen, The Netherlands. erika.silletti@nizo.nl <erika.silletti@nizo.nl>
Vitorino
Rui M P
RM
Schipper
Raymond
R
Amado
Francisco M L
FM
Vingerhoeds
Monique H
MH
D000327:Adsorption; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D004655:Emulsions / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007782:Lactoglobulins / Q000737:chemistry*; D008970:Molecular Weight; D055257:Mucin-5B / Q000737:chemistry; D009077:Mucins / Q000737:chemistry; D009113:Muramidase / Q000737:chemistry*; D009821:Oils / Q000737:chemistry; D012471:Salivary Proteins and Peptides / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry
D004655:Emulsions; D007782:Lactoglobulins; C524578:MUC5B protein, human; C083238:MUC7 protein, human; D055257:Mucin-5B; D009077:Mucins; D009821:Oils; D012471:Salivary Proteins and Peptides; D014867:Water; D009113:Muramidase