Fluorescence evidence for cholesterol regular distribution in phosphatidylcholine and in sphingomyeline lipid bilayers

Parkson Lee-Gau Chong; Mei Mei Wang; Fang Liu; Khanh Truong; Anthony A. Golsorkhi; Istvan P. Sugar; Rhoderick E. Brown

doi:10.1117/12.236184

25 March 1996 Fluorescence evidence for cholesterol regular distribution in phosphatidylcholine and in sphingomyeline lipid bilayers

Parkson Lee-Gau Chong, Mei Mei Wang, Fang Liu, Khanh Truong, Anthony A. Golsorkhi, Istvan P. Sugar, Rhoderick E. Brown

Author Affiliations +

Proceedings Volume 2705, Fluorescence Detection IV; (1996) https://doi.org/10.1117/12.236184
Event: Photonics West '96, 1996, San Jose, CA, United States

Abstract

Our previous studies indicated that sterols (including cholesterol and dehydroergosterol) can be regularly distributed into hexagonal superlattices in the plane of liquid-crystalline phosphatidylcholine bilayers. It was suggested that regular and irregular regions coexist in the membrane. In the present study, we report supporting evidence for our sterol regular distribution model. We have examined the fractional concentration dependencies of dehydroergosterol (a naturally occurring cholesterol analog) fluorescence intensity and lifetime in various phosphatidylcholine and sphingomyelin bilayers. Fluorescence intensity and lifetime dips have been observed at specific sterol mole fractions. At those mole fractions, the acrylamide quenching rate constant of dehydroergosterol fluorescence reaches a local maximum. Those mole fractions match with the critical sterol mole fractions at which sterol molecules are expected to be regularly distributed into hexagonal superlattices. The results support the idea that the sterols in the regular region are embedded in the bilayer less deep than those in the irregular regions. Furthermore, finding evidence for sterol regular distribution in both phosphatidylcholine and sphingomyelin membranes raises the possibility that sterol regular distribution may occur within phospholipid/cholesterol enriched domains of real biological membranes.

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Parkson Lee-Gau Chong, Mei Mei Wang, Fang Liu, Khanh Truong, Anthony A. Golsorkhi, Istvan P. Sugar, and Rhoderick E. Brown "Fluorescence evidence for cholesterol regular distribution in phosphatidylcholine and in sphingomyeline lipid bilayers", Proc. SPIE 2705, Fluorescence Detection IV, (25 March 1996); https://doi.org/10.1117/12.236184

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