| Method |
Liposomes (15 ml) were prepared from egg phosphatidylcholinc (211 raM) as described before, containing 0.5 M sodium chloride, 50 mM sodium borate buffer (pH 9.11), and 5 mM sodium citrate. Following preparation, sodium phosphate was added to a final concentration of 50 mM, and the external pH was adjusted with sulfuric acid to values ranging from near l to near 5. The liposomes were then incubated for periods up to 6 h. During this time l-ml aliquots were run through short Sephadex G-50 gel columns, and phosphate was deter- mined by the Lowry method. |