It is debated whether exercise-induced ROS production is obligatory to cause adaptive response. It is also claimed that antioxidant treatment could eliminate the adaptive response, which appears to be systemic and reportedly reduces the incidence of a wide range of diseases. Here we suggest that if the antioxidant treatment occurs before the physiological function-ROS dose-response curve reaches peak level, the antioxidants can attenuate function. On the other hand, if the antioxidant treatment takes place after the summit of the bell-shaped dose response curve, antioxidant treatment would have beneficial effects on function. We suggest that the effects of antioxidant treatment are dependent on the intensity of exercise, since the adaptive response, which is multi pathway dependent, is strongly influenced by exercise intensity. It is further suggested that levels of ROS concentration are associated with peak physiological function and can be extended by physical fitness level and this could be the basis for exercise pre-conditioning. Physical inactivity, aging or pathological disorders increase the sensitivity to oxidative stress by altering the bell-shaped dose response curve.
Force is increasingly recognized as an important element in controlling biological processes. Forces are able to deform native protein conformations leading to protein-specific effects. Here we demonstrate that the calcium-binding affinity of the actin-binding protein gelsolin domain G6 is enhanced by mechanical force. Using a recently developed single molecule-binding assay based on atomic force microscopy, we establish that the calcium-binding affinity of G6 increases exponentially with the applied force, up to the point of G6 unfolding. This implies that gelsolin will be activated at lower calcium ion levels when subjected to tensile forces and suggests a basis for enhanced cooperativity during multi-cation induced activation. 2P026 Direct observation of the multiple sliding modes of a tumor suppressor p53
RecBCD, which contains two helicases and a nuclease, plays important roles in DNA digestion and repair. We directly traced the enzyme functional process at high spatial (a few nanometers) and temporal (~0.3 s) resolution with high-speed atomic force microscopy. At the beginning, RecBCD bound to the end of dsDNA, while the other end labeled with biotin was blocked by streptavidin. When ATP was added, RecBCD translocated and digested dsDNA. After the reaction stopped at Chi which is a regulatory eight-nucleotide DNA sequence for ~10 s, RecBCD restarted to translocate and generated ssDNA. The movement of RecBCD was much less vigorous than before the pause. Thus, the functional processes of RecBCD, including Chi sequence recognition have been successfully visualized.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.