The phase transition temperature is defined as the temperature required to induce a change in the lipid physical state from the ordered gel phase, where the hydrocarbon chains are fully extended and closely packed, to the disordered liquid crystalline phase, where the hydrocarbon chains are randomly oriented and fluid. There are several factors which directly affect the phase transition temperature including hydrocarbon length, unsaturation, charge, and headgroup species. As the hydrocarbon length is increased, van der Waals interactions become stronger requiring more energy to disrupt the ordered packing, thus the phase transition temperature increases. Likewise, introducing a cis double bond into the acyl group puts a kink in the chain which requires much lower temperatures to induce an ordered packing arrangement.
A list of phase transition temperatures for selected lipids may be found on the following pages and sites:
- Phase Transition Temperatures for Glycerophospholipids
- Lipids For Liposome Formation
- Membrane Protein Data Bank (MPDB)
If the phase transition temperature is not listed on the above pages and sites then we must refer you to the literature. Note: Transition temperatures for natural products are typically not available in the literature. For processing (hydration and formulation) of natural lipids, we recommend the temperature of the medium should be above the gel-liquid crystal transition temperature (Tc or Tm) of any single lipid within the natural product.