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Zastosowanie spektroskopii oscylacyjnej w zakresie nir do śledzenia modyfikacji konformacyjnych zachodzących w hydrofobowym obszarze modelowych dwuwarstw lipidowych

Kuć Marta, Cieślik-Boczula Katarzyna, Rospenk Maria

Wiadomości Chemiczne

2023

[Z] 77, 7-8

647--686

Biomembranes, which are the structural and functional basis of the cells of all living organisms, have been an extremely interesting research object for biology and chemistry scientists for years. The multitude of elements constituting the components of natural lipid membranes, however, is associated with interpretation difficulties regarding the nature of the processes taking place in them. A useful research object that is a model of bilamellar biosystems with a significantly simplified composition and at the same time retaining properties that can be a reference point in relation to natural membranes are lipid membranes in the form of one or several component liposomes. It is precisely such systems built of molecules of dipalmitoyl phosphatidylcholine (DPPC) or dipalmitoyl phosphatidylglycerol (DPPG), and analogous systems with the addition of cholesterol (Chol), that were the subject of research in this work. Near-infrared (NIR) vibrational spectroscopy provides a suitable method for the study of the hydrated samples. In most cases it can be alternatively adopted instead of commonly used mid-infrared (MIR) vibrational spectroscopy. This technique was applied for the first time to identify the spectral changes associated with the conformational changes in the hydrophobic region of model lipid bilayers. Trans/gauche isomerization of CH2 groups of lipid hydrocarbon chains is accompanied by characteristic changes in spectral parameters of both νas,s CH2 bands and their first overtones (2νas,s CH2). The heating of all types of analyzed liposomes results in main phase transition (Tm) accompanied by trans to gauche isomerization of CH2 groups of lipid hydrocarbon chains. The NIR-spectroscopy was able to describe in proper way (similar to MIR results) the character of Tm in studied bilayers.

Wpływ anestetyków wziewnych na modelową błonę biologiczną

Horochowska Martyna, Cieślik-Boczula Katarzyna, Rospenk Maria

Wiadomości Chemiczne

2019

[Z] 73, 3-4

263--285

General anesthesia is defined as impairment of the central nervous system (UON) caused by intravenous or volatile anesthetics. The state of loss of consciousness or even amnesia and the disappearance of perception into external stimuli is achieved by the use of a large group of chemical compounds. The use of nitrous oxide in 1844 revolutionized surgery and medicine at that time. From that moment, anesthesiology develops dynamically, allowing more and more complex procedures. Despite more than 170 years of history of anesthesia, understanding the mechanism of reversible loss of awareness and sensitivity to pain caused by the action of general anesthetics is one of the greatest challenges of modern pharmacology and neuroscience. Incredibly high diversity of anesthetics, including both noble gases and complex steroids, combined with human sensation makes the above problem extremely difficult to solve. The reversibility of the anesthesia phenomenon suggests that the analyzed phenomenon is based on disturbance of weak intermolecular interactions, such as hydrogen bond or van der Walls forces. Anesthetic molecules may bind directly to the hydrophobic region of protein, which causes its conformational changes or disturb ion channel activity by anesthetic-induced perturbations of lipid bilayers. The mechanism of anesthesia is thus very often attributed to both protein and lipid membrane targets. The influence of anesthetic molecules on biomolecular systems can be studied successfully using many different physico-chemical methods, such as, infrared, fluorescence or nuclear magnetic resonance spectroscopy. Vibrational circular dichroism as well as differential scanning calorimetry can also be used.