Cholesterol is an important component of most cell membranes contributing to their organization and dynamics and helping to regulate a host of cellular processes. Understanding the detailed physical chemistry of these thermodynamic self-assembled systems is thus particularly important to properly appreciate the mechanisms of their critical cellular functions. We have undertaken a series of studies using contrasting matching techniques, coupled with MD simulations, to probe the solubility, organization and transfer of cholesterol within well controlled lipid membranes. Here we report results from two biologically relevant lipid membranes: POPC and POPS. Overall we find surprisingly slow cholesterol transport rates. However, while flipping rates are slow enough to be measurable in pure POPC systems that is not the case in POPS membranes. Further the energetics of cholesterol transfer exhibit an anomalous, discontinuous transition around 48C in POPS systems. Finally we find a surprisingly high cholesterol solubility in POPS membranes.

Exploring the energetics of cholesterol homeostasis

245th National Meeting (2013)

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