Avtor/Urednik		Štancar, J; Šentjurc, M; Schara, M
Naslov		Fast and accurate characterization of biological membranes by EPR spectral simulatios of nitroxides
Tip		članek
Vir		J Magn Reson
Vol. in št.		Letnik 142
Leto izdaje		2000
Obseg		str. 254-65
Jezik		eng
Abstrakt		Biological membranes have been investigated by various techniques allowing the evaluation of different membrane characteristics. Electron paramagnetic resonance (EPR) spectroscopy based on labeling with nitroxide spin probes (SP) has proven to be a powerful method for studying biological membranes (1, 2). It can detect alterations induced by biologically active substances or the involvement of pathological conditions (3-5). The recorded EPR spectra should be simulated to extract reliable and biologically meaningful parameters. It is important to point out the coexistence of lateral domains in biological membranes, which recently became evident as a result of a number of different approaches (6-9). Additionally, the lateral diffusion of spin-labeled fatty acids and their derivatives is too slow with respect to the EPR CW time scale to average out the differences between the domains. Consequently, this heterogeneous structure of cell membranes results in superimposed spectra composed of several spectral components of the particular domains. Although translational diffusion is slow with respect to EPR CW, it should be stressed that under physiological conditions the rotational motions of molecules are fast. Generally, to describe the EPR spectra of spin probes, the stochastic Liouville equation is used (10,11 ). In a membrane system where molecular rotational motions are fast with respect to the EPR time scale, this approach can be simplified (2,12-14), and the magnetic interaction tensors can be averaged over the stochastic rotational motions of the spin-probe molecules. Subsequently, the spin Hamiltonian with averaged tensor components can be used to calculate lineshapes for the spin-probe molecules in membrane segments with a particular orientation relative to the external magnetic field. The spectra of the randomly oriented cell membrane segments are finally summed to get the inhomogeneously broadened spectra. (Abstract truncated at 2000 characters.)
Deskriptorji		CELL MEMBRANE PERMEABILITY NITROUS OXIDE ELECTRON SPIN RESONANCE SPECTROSCOPY LEUKOCYTES MEMBRANES, ARTIFICIAL BENZOATES MODELS, THEORETICAL MONTE CARLO METHOD SPIN LABELS PALMITATES