Τμήμα Χημείας

Comparison of the thermal behavior and conformational changes in partially and fully hydrated dipalmitoylphosphatidylcholine systems

Αγγλικά

The temperature dependence of conformational
changes for partially and fully hydrated DPPC systems
through two physicochemical techniques, namely DSC and
Raman spectroscopy, is studied. DSC experiments have
shown a different thermal behavior between the two considered systems, indicating the effective role of water in the
thermal behavior. A temperature resolution of inter- and
intramolecular interactions during the main melting phase
transition was achieved by using three different Raman
intensity ratios, which confirm that the main phase transition represents a two-stage transition. Van’t Hoff plots for
the C–C, C–H, C=O and C4N? stretching modes, in a
temperature range just below the main transition temperature, have been used to compare the thermodynamic
parameters extracted by the two physicochemical techniques. The significance of these results can be summarized
as follows: (a) DSC and Raman spectroscopy have shown
complementary results indicating that DPPC exists in
partially or fully hydrated states; (b) thermodynamic
parameters DH and DS calculated in both techniques for the
two different hydration states of DPPC were in harmony;
(c) water more significantly affects the thermal and
dynamic properties of fully hydrated DPPC bilayers than of
the partially hydrated DPPC; and (d) water disturbs the
head-group packing, the alkyl chains interactions and the
mesophase region. It appears that the amount of water
plays a vital role in the bilayer structure. As more and more
extensive studies appear in the literature on biomolecules
or drug membrane interactions, this information will be
valuable in understanding the role of water in these
interactions.

2017

P. Chatzigeorgiou, A. Mourelatou, E. Pallatos, T. Mavromoustakos, C.E. Semidalas

Journal of Thermal Analysis and Calorimetry

SPRINGER

67

11

1-12

Dipalmitoylphosphatidylcholine  DSC  Raman spectroscopy  van’t Hoff plots

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