Abstract:
:Numerous dyes are available or under development for probing the structural and functional properties of biological membranes. Exogenous chromophores adopt a range of orientations when bound to membranes, which have a drastic effect on their biophysical behavior. Here, we present a method that employs optical anisotropy data from three polarization-imaging techniques to establish the distribution of orientations adopted by molecules in monolayers and bilayers. The resulting probability density functions, which contain the preferred molecular tilt μ and distribution breadth γ, are more informative than an average tilt angle [φ]. We describe a methodology for the extraction of anisotropy data through an image-processing technology that decreases the error in polarization measurements by about a factor of four. We use this technique to compare di-4-ANEPPS and di-8-ANEPPS, both dipolar dyes, using data from polarized 1-photon, 2-photon fluorescence and second-harmonic generation imaging. We find that di-8-ANEPPS has a lower tilt but the same distributional width. We find the distribution of tilts taken by di-4-ANEPPS in two phospholipid membrane models: giant unilamellar vesicles and water-in-oil droplet monolayers. Both models result in similar distribution functions with average tilts of 52° and 47°, respectively.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Reeve JE,Corbett AD,Boczarow I,Wilson T,Bayley H,Anderson HLdoi
10.1016/j.bpj.2012.08.003subject
Has Abstractpub_date
2012-09-05 00:00:00pages
907-17issue
5eissn
0006-3495issn
1542-0086pii
S0006-3495(12)00861-2journal_volume
103pub_type
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