On the shift in membrane miscibility transition temperature upon addition of short-chain alcohols

TL;DR

This paper analyzes how small concentrations of short-chain alcohols affect the miscibility transition temperature of plasma membrane vesicles, highlighting the role of molecular partitioning and providing predictions consistent with recent experimental findings.

Contribution

It offers a theoretical framework linking alcohol partitioning behavior to shifts in membrane phase transition temperatures, supported by calculated partition coefficients.

Findings

Partitioning into liquid-disordered phase lowers transition temperature

Partitioning into liquid-ordered phase raises transition temperature

Provides testable predictions for experimental validation

Abstract

I consider the effect of a small concentration of a molecule, such as a short-chain alcohol, on the miscibility transition temperature of a giant plasma membrane vesicle. For concentrations sufficiently small such that the system can be treated as a weak solution, the change in transition temperature is known to depend upon the extent of the molecule's partition into the coexisting liquid-disordered and liquid-ordered phases. Preferential partitioning into the former decreases the miscibility temperature, while preferential partitioning into the latter causes an increase. The analysis, combined with calculated values of the partition coefficient of saturated chains, illuminates the results of recent experiments on the change in miscibility transition temperatures with changing alcohol chain length, and makes several testable predictions.