METASTABLE BEHAVIOR OF SATURATED PHOSPHATIDYLETHANOLAMINES - A DENSITOMETRIC STUDY

The specific volumes of saturated phosphatidylethanolamines having 12-18 carbon atoms per chain and the volume changes resulting from their temperatures-induced phase transitions have been investigated using differential scanning densitometry. No dependence on acyl-chain length has been found for the molar volume changes associated with the Lc → Lα transition, while the Lβ → Lα transition showed ΔV-changes that increase with the length of the acyl-chains. The independence of acyl-chain length of the molar volume changes concomittant with the Lc → Lα transition can be rationalized by the assumption that the volume changes result from the combined effects of hydration and acyl chain melting. An interesting corollary of the present studies is the disappearance of metastability at chain lengths of about 20-22 carbon atoms. © 1990.