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Conformational Changes as Driving Force for Phase Recognition: The Case of Laurdan
journal contribution
posted on 2019-08-23, 18:38 authored by Silvio Osella, Nick Smisdom, Marcel Ameloot, Stefan KnippenbergThe
development of a universal probe to assess the phase of a lipid
membrane is one of the most ambitious goals for fluorescence spectroscopy.
The ability of a well-known molecule as Laurdan to reach this aim
is here exploited as the behavior of the probe is fully characterized
in a dipalmitoylphosphatidylcholine (DPPC) solid gel (So) phase by
means of molecular dynamics simulations. Laurdan can take two conformations,
depending on whether the carbonyl oxygen points toward the β-position
of the naphthalene core (Conf-I) or to the α-position (Conf-II).
We observe that Conf-I has an elongated form in this environment,
whereas Conf-II takes an L-shape. Interestingly, our theoretical calculations
show that these two conformations behave in an opposite way from what
is reported in the literature for a DPPC membrane in a liquid disordered
(Ld) phase, where Conf-I assumes an L-shape and Conf-II is elongated.
Moreover, our results show that in DPPC (So) no intermixing between
the conformations is present, whereas it has been seen in a fluid
environment such as DOPC (Ld). Through a careful analysis of angle
distributions and by means of the rotational autocorrelation function,
we predict that the two conformers of Laurdan behave differently in
different membrane environments.
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Ldcarbonyl oxygen pointsprobeangle distributionslipid membranefluid environmentresults showConf-IIL-shapecalculations showLaurdanautocorrelation functionDPPC membranenaphthalene coreDOPCfluorescence spectroscopyconformationPhase Recognitionmembrane environmentsphaseConformational Changesdynamics simulationsConf-Iα- positionβ- position
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