We have constructed the model of lipid membrane of Archaea Aeropyrum pernix. The model of membranes were simulated at different temperatures using molecular dynamics. The membranes were examined to the electric stress. The voltage across the membrane was induced by charge imbalance method. The archaeal membranes were electroporated at much higher voltages than PC-based lipid bilayers. The study also shows the effect of mixing archaeal lipids with DPPC. Addition of DPPC into the archaeal lipid membrane lowers electroporation threshold. The electron density profiles of our membrane models are in good with experimentally measured profiles using SAXS. This give us the confidence in our force field. The creation of the pore under electric field is not similar to PC-based lipids. In the archaeal lipid membrane we observed only conducting hydrophobic pore. The pore never stabilize by bending lipid headgroups into the interior of the membrane.
COBISS.SI-ID: 4362104
The paper presents the system for measuring planar lipid bilayer properties. The system is composed of a control unit, an output stage, LCR meter, pumps for filling reservoirs, a bath with temperature regulation and a measurement chamber with four electrodes. The planar lipid bilayer is automatically formed by folding method on apertures of different sizes. The automatization is assured by two syringes which are clamped in actuators. Actuators are driven and controlled by control unit via RS-232 communication. The temperature of planar lipid bilayer can be regulated between 15 °C and 55 °C. The regulation is assured by insertion of measurement chamber into the temperature regulated bath. Different shapes of voltage or current clamp signals can be applied to planar lipid bilayer. By measuring the planar lipid bilayer response to applied signal, planar lipid bilayer capacitance and breakdown voltage can be determined. The cutoff frequencies of the system output stage are 11 kHz and 17 kHz for voltage clamp method and current clamp method respectively.
COBISS.SI-ID: 9398356
The physicochemical properties of binary lipid mixtures of diether C(25,25) lipids and dipalmitoylLphosphatidylcholine (DPPC) were studied using photon correlation, fluorescence and electron paramagnetic resonance spectroscopy, and transmission electron microscopy.
COBISS.SI-ID: 3924088
We present experimental and theoretical results of electroporation of small patches of planar lipid bilayers by means of linearly rising current. We recorded small voltage drops preceding the breakdown of the bilayer due to irreversible electroporation. These voltage drops were often followed by a voltage re-rise within a fraction of a second. Modeling the observed phenomenon by equivalent electric circuits showed that these events relate to opening and closing of conducting pores through the bilayer. Molecular dynamics simulations performed under similar conditions indicate that each event is likely to correspond to the opening and closing of a single pore of about 5 nm in diameter, the conductance of which ranges in the 100-nS scale.
COBISS.SI-ID: 9484628
Current electroporation theory assumes that the membrane is permeabilized through the formation of conducting hydrophilic pores, stabilized by rearrangement of lipid head groups. Here we have performed molecular dynamics simulations of negatively charged lipid bilayers subject to high transmembrane voltages together with electroporation experiments on planar bilayers. Our data reveal a hitherto unknown electroporation process in which large ion-conducting water columns not stabilized by lipid head groups are formed within the bilayer’s hydrophobic core.
COBISS.SI-ID: 10507348