Da. Johnson et al., Paramagnetic fluorescence quenching in a model membrane: a consideration of lifetime and temperature, BIOPHYS CH, 79(1), 1999, pp. 1-9
To expand our understanding of paramagnetic quenching in membranes, the rel
ationship between fluorophore excited-state lifetime (tau), temperature, an
d the collisional quenching was studied. Specifically, the ability of tempo
to quench the steady-state and time-resolved emission from five lipophilic
fluorophores (diphenylhexatriene, perylene, phenanthrene, pyrene, and trip
henylene) partitioned into egg phosphatidylcholine (EggPC) liposomes was ex
amined. Also, the temperature dependence of spin-labeled androstane to quen
ch the emission (steady-state and time-resolved) from perylene in EggPC lip
osomes was determined. Unexpectedly, in EggPC liposomes, the apparent quenc
hing efficiency decreased with increasing tau until the effect leveled off
above similar to 20 ns. Moreover, in EggPC liposomes, dynamic quenching dec
reased with increasing temperature. The results suggest that in membranes,
paramagnetic quenching is more complex than generally recognized. (C) 1999
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