Date of Award

Spring 1986

Degree Type

Thesis - Restricted

Degree Name

Master of Science (MS)



First Advisor

Collins, Joseph M.

Second Advisor

Tani, Smio

Third Advisor

Feldott, Jeanette


POPC is believed to be a synthetic analogue to the naturally occuring Egg-Yolk Lecithin (EYPC) which was always observed to undergo phase separation when stressed in 30mM CaC12 . However, we demonstrate in this thesis that PO PC is not an analogue to the naturally occurring EYPC. POPC with a mixture of acyl chains does not induce phase separation when stressed in 30mM CaCl2 , but behaves as a single species lipid. X-Ray diffraction methods were used to characterize and measure the interbilayer forces of POPC in distilled water and in 30mM CaCl2. The osmotic pressure technique of Le Neveu et al. [Nature 259 (1976) 601-603] was used for a force analysis of POPC. We observed the formation of a single lamellar phase in POPC hydrated in distilled water and in 30mM CaCl2 at room temperature. We characterized and measured the interbilayer forces. The intrabilayer forces apparently underwent a change yielding the formation of vesicles for bilayer separation distances greater than 45A; while the interbilayer forces remained unmodified as compared to single species PC's.