Structural design of intrinsically fluorescent oxysterols

Area of Science:

• Biochemistry
• Molecular Biology
• Biophysics

Background:

• Oxysterols, oxidized cholesterol derivatives, have crucial biological roles.
• Intracellular oxysterol trafficking remains poorly understood due to a lack of suitable analogs.
• Fluorescent oxysterol probes offer a novel approach for direct visualization of oxysterol dynamics.

Purpose of the Study:

• To characterize the fluorescence properties of existing and novel fluorescent oxysterol analogs.
• To investigate the membrane localization and photophysical properties of these probes.
• To assess their potential for imaging intracellular oxysterol transport.

Main Methods:

• Characterization of fluorescence properties of 25-hydroxycholestatrienol and a novel analog.
• Molecular dynamics simulations to compare probe and 25-hydroxycholesterol membrane localization.
• Electronic structure calculations with polarizable embedding for absorption properties.

Main Results:

• Both analogs show potential as probes for 25-hydroxycholesterol.
• The novel analog exhibits significant two-photon absorption, enhanced within a membrane.
• Keto-enol tautomerism of the new analog was considered, with the enol form being the preferred probe.

Conclusions:

• Fluorescent oxysterol analogs are valuable tools for studying oxysterol trafficking.
• The novel analog with an extended conjugated system is a promising candidate for advanced microscopy techniques.
• Membrane environments significantly influence the photophysical properties of these fluorescent probes.