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Rezumat articol ediţie STUDIA UNIVERSITATIS BABEŞ-BOLYAI
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Rezumat: Permeable membranes are basic structural and functional constituents of living systems. All biological membranes possess a common basic structure. Vertical dimensions range up to about 10 nm. The high variety of membrane components (lipids, proteins, sterols, pigments, etc.) causes a high variety of constitutional conformations. The forces which keep together the structure are of covalent, ionic or entropic nature. According to this wide frame, the physical properties of biological membranes are subjected to local and temporal changes. Most important physical membrane properties are membrane fluidity, active and passive membrane permeability, membrane anisotropy and the ability to incorporate molecules from the extracellular space being biotics or xenobiotics. The incorporation of molecules may have adverse biological effects on membranes like toxins. Or they may constitute the biological function of the membrane as is the case with pigments. Carotenoids are a class of pigments which are widely abundant in nature with more than 600 molecular species. Many of them are of profound significance for life: light harvester in photosynthesis, vitamin A precursors in the vision process, UV protection function in the eye, pigmentation of many plants, animal skins and feathers, antioxidative and antibiotic actions. The knowledge about these and many other health beneficial effects are of empirical origin. Biophysical and biochemical action mechanisms are poorly understood so far. Carotenoids are more or less lipophilic compounds and their action is bound mainly to membranes. How do carotenoids pass or incorporate into membranes, how do they locate in membranes, how stable are they and what is their specific impact on the membrane? And which methods promise access to answers? |
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