Accessibility of Membrane Probes to Water- and Lipid-Soluble Quenchers

During the past 15 years, there have been numerous studies of quenching in membranes. These experiments had a number of goals, including determination of the accessibility of probes to water- and lipid-soluble quenchers, determination of quencher partitioning into membranes, localization of probes in membranes relative to the lipid-water interface, and measurement of lateral diffusion co- 

Accessibility of Membrane Probes to Water- and Lipia-Soluble Quenchers 

Since the early studies of membranes labeled with fluorescent probes, there has been an extensive effort to determine the location of the probes in the memtx es. Early membrane probes, such as perylene, 9-vinylanthrac e, and were simple hydrophobic molecules that dissolved in the hydrophobic regions of micelles or mem-Ixmies. SubsequOTt probes woe synthesized and designed to localize the fluorophoie at various depths in the membrane. Among the earliest of such probes were theandiroyl- 

The diemical structures of the li Hd probes usually sug gest their locaticm in a membnuie. However, diis localization needed to be experimentally confiimed. In fact, diis 

Another example of membrane-localized probes is no-vided by the series of NBD-labeled li ds shown in Hgm 9.6. In order to obtain a sutfiice-localized probe, NBD-dtloride was reacted with phospfaatidylelhanoiamine to yidd NBD-FE. In order to obtain localization at various dqtdis in die membrane, the NBD group was attached to 6-carbon (6-NBD-PA PA is phosphalidic acid) or 12-cwbon (12-NBD-PC) acyl chains. NBD was also attached to cholesterol. 

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