Preferential interactions of fluorescent probe Prodan with cholesterol

Area of Science:

• Membrane biophysics
• Fluorescent probe applications
• Lipid phase behavior

Background:

• Prodan is a fluorescent probe used for studying model and biological membranes.
• Prodan's fluorescence spectra indicate lipid phase states: liquid crystal (485 nm), gel (435 nm), and interdigitated gel (507 nm).

Purpose of the Study:

• To investigate Prodan's fluorescent properties and partition coefficients in model membranes with varying lipid phase states and cholesterol content.
• To determine if cholesterol affects Prodan's spectral response to lipid phase states.

Main Methods:

• Studied fluorescent properties and partition coefficients of Prodan in phosphatidylcholine and phosphatidylethanol model membranes.
• Varied lipid phase state and cholesterol content in model membranes.
• Analyzed Prodan's emission maxima and partition coefficients under different conditions.

Main Results:

• Cholesterol disrupts Prodan's ability to report on lipid phase state, causing spectra characteristic of the non-interdigitated gel phase (435 nm) regardless of the actual phase.
• Cholesterol significantly increases Prodan's partition coefficients into lipid bilayers.
• Prodan exhibits preferential interaction with cholesterol, indicating non-random distribution in cholesterol-containing membranes.

Conclusions:

• Prodan is not a reliable reporter probe in membranes containing cholesterol due to preferential interactions.
• Caution is advised when using Prodan in complex lipid mixtures, especially biological membranes, due to cholesterol interference.