title: Determination of the phase behaviour of phosphatidylethanolamine admixed with other lipids and the effects of calcium chloride: implications for protein kinase C regulation.
abstract: The phase behaviour of 1-palmitoyl-2-oleoylphosphatidylethanolamine (POPE) was studied by differential scanning calorimetry and 31P-NMR spectroscopy. Modulation of the phase behaviour of POPE by 1-palmitoyl-2-oleoylphosphatidylserine (POPS). 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), 1,2-di-olein (DOG), CaCl2, MgCl2, and combinations of these substances was studied. The bilayer-forming lipids, POPS and POPC, raise the bilayer-to-hexagonal phase-transition temperature of POPE. The POPC has a greater effect than POPS, probably because the former lipid is more miscible with POPE. Addition of 10 mM CaCl2 has little effect on the phase-transitions of POPE/POPC mixtures, but it greatly decreases the effectiveness of POPS in raising the bilayer-to-hexagonal phase-transition temperature of POPE. The effectiveness of DOG in lowering the phase-transition temperature of POPE is also greatly reduced in the presence of 10 mM CaCl2. This phenomenon may play a role in the negative feedback regulation of protein kinase C.
authors.affiliation: Department of Biochemistry, McMaster University Health Sciences Centre, Hamilton, Ontario, Canada.
authors.forename: R M
authors.initials: RM
authors.lastname: Epand
authors.forename: R
authors.initials: R
authors.lastname: Bottega
mesh_terms: D002122:Calcium Chloride / Q000494:pharmacology*; D002152:Calorimetry, Differential Scanning; D004075:Diglycerides; D009682:Magnetic Resonance Spectroscopy; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010718:Phosphatidylserines; D011493:Protein Kinase C / Q000378:metabolism*
chemical_list: D004075:Diglycerides; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010718:Phosphatidylserines; C057561:1-palmitoyl-2-oleoylphosphatidylethanolamine; C050294:1-palmitoyl-2-oleoylglycero-3-phosphoserine; D011493:Protein Kinase C; D002122:Calcium Chloride; C028694:1-palmitoyl-2-oleoylphosphatidylcholine; C013965:diolein