title: Monitoring cholesterol organization in membranes at low concentrations utilizing the wavelength-selective fluorescence approach.
abstract: We previously showed using a fluorescent analogue of cholesterol (NBD-cholesterol, or 25-[N-[(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-methyl]amino]-27-norcholesterol), that cholesterol may exhibit local organization at low concentrations in membranes by the formation of transbilayer tail-to-tail dimers of cholesterol (Rukmini, R., Rawat, S.S., Biswas, S.C., Chattopadhyay, A., 2001. Biophys. J. 81, 2122-2134). In this report, we have monitored the microenvironmental features of cholesterol monomers and dimers utilizing wavelength-selective fluorescence spectroscopy. Our results utilizing red edge excitation shift (REES) and wavelength-dependent change in fluorescence anisotropy show that the microenvironment around the NBD moieties in the dimer form is more rigid possibly due to steric constraints imposed by the dimer conformation. These results provide new information and are relevant in understanding the organization of cholesterol in membranes at low concentrations.
authors.affiliation: Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India.
authors.forename: Soumi
authors.initials: S
authors.lastname: Mukherjee
authors.forename: Amitabha
authors.initials: A
authors.lastname: Chattopadhyay
mesh_terms: D002462:Cell Membrane / Q000737:chemistry; D002784:Cholesterol / Q000737:chemistry*; D019281:Dimerization; D005454:Fluorescence Polarization; D008563:Membrane Lipids / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D008563:Membrane Lipids; D002784:Cholesterol