Browsing by Author "Severcan, F"

Now showing 1 - 2 of 2

Citation - WoS: 5
Citation - Scopus: 5
Concentration Dependent Different Action of Progesterone on the Order, Dynamics and Hydration States of the Head Group of Dipalmitoyl-Phosphatidylcholine Membrane
(Hindawi Ltd, 2005) Korkmaz, F; Kirbiyik, H; Severcan, F
Interactions of progesterone with zwitterionic dipalmitoyl phosphatidylcholine (DPPC) multilamellar liposomes (MLVs) were investigated as a function of progesterone concentration at selected temperatures monitoring both the gel and liquid crystalline phase, by using Fourier Transform Infrared spectroscopy (FTIR). It has been show that the effect of progesterone on membrane dynamics is dependent on progesterone concentration. At 1 mol%, which is close to physiological level, progesterone behaves differently. At this concentration the decrease in dynamics is more noticeable. Additionally a dramatic decrease in the strength of hydrogen bonding in the interfacial region of the bilayer is also observed. When concentration increases up to 12 mol% opposite behaviour is observed at all interactions. Above 12 mol%, progesterone-DPPC interactions shows almost linear plot.
Citation - WoS: 94
Citation - Scopus: 98
Effect of Progesterone on Dppc Membrane: Evidence for Lateral Phase Separation and Inverse Action in Lipid Dynamics
(Elsevier Science inc, 2005) Korkmaz, F; Severcan, F
Interactions of progesterone with zwitterionic dipalmitoyl phosphatidylcholine (DPPC) triultilamellar liposomes were investigated as a function of temperature and progesterone concentration by using three non-invasive techniques namely Fourier transform infrared spectroscopy, turbidity at 440 nm, and differential scanning calorimetry. The results reveal that progesterone changes the physical properties of DPPC bilayers by decreasing the main phase-transition temperature, abolishing the pre-transition, broadening the phase-transition profile, disordering the system both in gel and liquid crystalline phase, increasing the dynamics at low concentrations whereas stabilizing the membrane at high concentrations, and inducing phase separation. Progesterone does not change the hydration of the C=O groups, while it strengthens the hydrogen bonding between the PO (2) over bar groups of lipids and the water molecules around. (c) 2005 Elsevier Inc. All rights reserved.