Theory of biomembrane phase transitions

TLDR: In this article, a pair of two dimensional lattice models (A and B) are introduced and the statistical mechanics is solved exactly using dimer techniques, and the phenomenological parameters required by the models are evaluated from experiments on other systems.

Abstract: Experiments on the chain melting thermal transition in simple biological membranes are briefly reviewed and shown to indicate that a microscopic order‐disorder model may be appropriate to describe the thermodynamics of the transition. To test this conclusion further a pair of two dimensional lattice models (A and B) are introduced and the statistical mechanics is solved exactly using dimer techniques. The phenomenological parameters required by the models are evaluated from experiments on other systems. The more realistic of the two models (model A) has a second order transition at a temperature of 353°K compared to 315°K for dipalmitoyl‐L‐α‐lecithin membranes. However, the specific heat peaks do not have the same shape and the transition is broader for model A than for the experiment. In comparison, the less realistic model B has a first order transition at 925°K, considerably higher than the experimental transition temperature. From these results it seems likely that the points of disagreement between m...