X-ray total external reflection fluorescence has been applied to detect an angular dependence of fluorescence yield modulated by evanescent/X-ray standing wave pattern from metal-rich organic monolayer alone on water surface. Theoretical consideration reveals that electric field intensity in a molecular monolayer is completely determined by an area per one molecule value that can be obtained from pressure-area isotherm. This allows getting an ion position inside a monolayer from the corresponding fluorescence angular dependence. The possibilities of the technique have been used at the SR beamline ID10B (ESRF) to characterize Langmuir monolayers of phthalocyanines and cyclolinear polyorganosiloxanes formed on air/water interface.
The paper overviews the peculiarities of carbonyl stress in nucleus-free mammal red blood cells (RBCs). Some functional features of RBCs make them exceptionally susceptible to reactive carbonyl compounds (RCC) from both blood plasma and the intracellular environment. In the first case, these compounds arise from the increased concentrations of glucose or ketone bodies in blood plasma, and in the second—from a misbalance in the glycolysis regulation. RBCs are normally exposed to RCC—methylglyoxal (MG), triglycerides—in blood plasma of diabetes patients. MG modifies lipoproteins and membrane proteins of RBCs and endothelial cells both on its own and with reactive oxygen species (ROS). Together, these phenomena may lead to arterial hypertension, atherosclerosis, hemolytic anemia, vascular occlusion, local ischemia, and hypercoagulation phenotype formation. ROS, reactive nitrogen species (RNS), and RCC might also damage hemoglobin (Hb), the most common protein in the RBC cytoplasm. It was Hb with which non-enzymatic glycation was first shown in living systems under physiological conditions. Glycated HbA1c is used as a very reliable and useful diagnostic marker. Studying the impacts of MG, ROS, and RNS on the physiological state of RBCs and Hb is of undisputed importance for basic and applied science.
The X-ray standing-wave method was applied to study the elemental composition and molecular organization of ordered protein films of alkaline phosphatase exposed to different xenobiotics (drug compounds, lead). Binding of metal ions from triply distilled water to protein molecules has been experimentally observed. Definite differences in the arrangement of impurity metal ions in the films have been established. The considerable enhancement of protein-metal interactions is attributed to partial rearrangement of the protein native structure, induced by xenobiotics.
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