Melatonin induces opposite effects on order and dynamics of anionic DPPG model membranes

Sahin, Ipek
Severcan, Feride
Kazanci, Nadide
The temperature and concentration induced effects of melatonin on anionic dipalmitoyl phosphatidylglycerol (DPPG) multilamellar liposomes (MLVs) were investigated by using Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The results show that melatonin does not perturb the phase transition profile, while a decrease in the main transition temperature (T-m) is noticed at high melatonin concentrations (15, 24 and 30 mol Low concentrations of melatonin (3, 6 and 9 mol %) decrease the frequency of the CH2 stretching mode, implying an ordering effect, whilst high concentrations of melatonin disorders system both in the gel and liquid crystalline phases. Furthermore, at low and high concentrations, melatonin also causes opposite effect on membrane dynamics. The bandwidth of the CH2 stretching modes decreases at low concentrations, implying a decrease in the dynamics, while increasing it at high concentrations. Furthermore, it causes significant decrease in the frequency of the C=O stretching and PO2- antisymmetric double bond stretching bands of DPPG for all concentrations both in the gel and liquid crystalline phases, which indicates strong hydrogen bonding around these functional groups.


Resonant frequency shifts related to the elastic constants near the alpha-beta transition in quartz
Yurtseven, Hasan Hamit (Elsevier BV, 2019-03-05)
The resonant frequency shifts of vibrational modes are related to the elastic constants at various temperatures for the alpha-beta transition in quartz (T-c = 573.0 degrees C for alpha-quartz and 574.3 degrees C for beta-quartz). This correlation is constructed on the basis of the spectroscopic modifications of the Pippard relations near the alpha-beta transition in quartz by using the observed data from the literature.
Estimation of protein secondary structure from FTIR spectra using neural networks
Severcan, M; Severcan, Feride; Haris, PI (Elsevier BV, 2001-05-30)
Secondary structure of proteins have been predicted using neural networks (NN) from their Fourier transform infrared spectra. Leave-one-out approach has been used to demonstrate the applicability of the method. A form of cross-validation is used to train NN to prevent the overfitting problem. Multiple neural network outputs are averaged to reduce the variance of predictions. The networks realized have been tested and rms errors of 7.7% for alpha -helix, 6.4% for beta -sheet and 4.8% for turns have been achi...
Vibrational frequencies studied as a function of pressure in phase II of solid benzene
Yurtseven, Hasan Hamit; Kilit, E. (Elsevier BV, 2011-05-03)
The pressure dependence of the vibrational frequencies of six Raman modes is analyzed in phase II of solid benzene. The frequency shifts 1/nu(partial derivative nu/partial derivative P)(T) of those Raman modes are deduced from this analysis and they are related to the isothermal compressibility kappa(T)= -(1/V)(partial derivative V/partial derivative P)(T) through a constant isothermal mode Gruneisen parameter gamma(T) in phase II of solid benzene. The kappa(T) values predicted here are compared with the ka...
Carboligation reactivity of benzaldehyde lyase (BAL, EC covalently attached to magnetic nanoparticles
TURAL, Bilsen; Turan, Ilke Simsek; TURAL, SERVET; Celebi, Bulent; Demir, Ayhan Sıtkı (Elsevier BV, 2013-03-31)
Epoxy-functionalized Fe3O4-SiO2 core-shell magnetic nanoparticles (epoxy-M-support) were prepared by modification with glycidyloxypropyltrimethoxysilane (GPTMS) and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and fourier transform infrared spectroscopy (FTIR) methods. Pure histidine-tagged recombinant benzaldehydelyase (BAL, EC 4.1.238) was efficiently immobilized onto the epoxy-M-support with covalent binding. An immobilized BAL epoxy-M-support system was tested to cat...
Raman bandwidths calculated for the librational ( a -phase) and internal (8, d loc and d phases) modes in solid N 2 using pseudospin-phonon coupling (PS) and energy-fluctuation (EF) models
Yurtseven, Hasan Hamit (Elsevier BV, 2020-10-01)
This study gives the calculation of the Raman bandwidths using the models of the pseudospin-phonon coupling (PS) and energy fluctuation (EF) where the Raman frequency calculated from the molecular field theory, is considered as the order parameter close to the phase transitions in nitrogen. In particular, we study the temperature dependence of the Raman bandwidths and frequency shifts of the Eg librational mode (zero pressure) and the internal modes of and (at various pressures) for the solid nitrogen by ...
Citation Formats
I. Sahin, F. Severcan, and N. Kazanci, “Melatonin induces opposite effects on order and dynamics of anionic DPPG model membranes,” JOURNAL OF MOLECULAR STRUCTURE, pp. 195–201, 2007, Accessed: 00, 2020. [Online]. Available: