Influence of low-level laser radiation on the physico-chemical indicators of biomembranes

Background: The study of physical and molecular mechanisms of the influence of low-level laser radiation (LLLR) of a wide frequency range on biological objects allows to clarify the problem of laser photomodulation at the level of natural biological membranes and their model analogues. Objectives: Identification of molecular and physical mechanisms of the influence of LLLR of a wide frequency range on biological objects of various levels of complexity. Materials and methods: Research objects: unicellular organisms S. cerevisiae, concentration of cells in the sample 18×106; model lipid membranes from a mixture of phosphatidylcholine and cardiolipin with different content of components (10%, 20% and 40% cardiolipin), which simulates the surface electrical properties of lipid models. A spectrophotometric study of charge redistribution on the cell surface was carried out using bromothymol blue dye. Complex formation of cytochrome c with model membranes was studied spectrophotometrically at the wavelength of the Soret band (405–410 nm). The influence of low-intensity laser radiation with wavelength and power density, respectively: 337 nm, 2.8 mW/cm2; 532 nm, 9.5 mW/cm2; 70.5 μm, 10.0 mW/cm2 on the yeast cell surface; 632.8 nm, 5.1 mW/cm2 on liposomes with different protein-lipid composition. Results: LLLR of a wide frequency range causes a change in the surface electrical properties of S. cerevisiae cells, namely, a redistribution of the surface charges of the cell membrane, as a result of which a change in the surface membrane potential is recorded. Irradiation of samples of model lipid membranes with a helium-neon laser leads to a change in the surface characteristics of liposomes, which affects the kinetic parameters of the formation of protein-lipid complexes with the participation of cytochrome c. Conclusions: The target of laser photomodulation processes is the surface of the biological membrane of both natural cells, for example yeast cells, and model lipid membranes made of a mixture of phospholipids with different content of components. The creation of lipid models based on the protein and lipid composition of natural membranes makes it possible to predict the reaction of cell membranes to the action of LLLR in the model, and to understand the molecular mechanisms of laser photomodulation processes.