Sphingomyelin from bovine milk and water form lipid el phases at room
temperature. A sample was used which incorporated of about 55%, water,
and X-ray diffraction data indicate an aqueous layer thickness of abo
ut 28 Angstrom. In order to accommodate proteins in the gel phase, the
aqueous layer thickness was increased by solubilizing sodium palmitat
e into the sphingomyelin bilayer. In this way the gel phase could take
up about 80% water. The incorporation of lysozyme, beta-lactoglobulin
, and alpha-lactalbumin, was followed and the protein concentration fo
r phase separation to occur was determined. It was found that the degr
ee of incorporation was dependent on the salt concentration, thus the
protein used was extensively dialysed. The amount of protein which can
be dissolved in the thin aqueous layer of the gel phase was suggested
to be limited by the dimensions of the layer. These are likely to be
reduced as a consequence of the osmotic stress exerted by the 'outside
' solution phase at:high enough protein concentration.