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PAL-XFEL soft X-ray scientific instruments and X-ray optics: First commissioning results
Park, Sang Han,Kim, Minseok,Min, Changi-Ki,Eom, Intae,Nam, Inhyuk,Lee, Heung-Soo,Kang, Heung-Sik,Kim, Hyeong-Do,Jang, Ho Young,Kim, Seonghan,Hwang, Sun-min,Park, Gi-Soo,Park, Jaehun,Koo, Tae-Yeong,Kwo American Institute of Physics 2018 Review of scientific instruments Vol.89 No.5
Park, Jaeheung,Lee, Taegon,Park, Jaehun,Lim, Manho American Chemical Society 2013 The journal of physical chemistry. B, Condensed ma Vol.117 No.10
<P>Femtosecond vibrational spectroscopy was used to investigate the photoexcitation dynamics of NO-bound ferric myoglobin (Mb<SUP>III</SUP>NO) in D<SUB>2</SUB>O solution at 294 K after excitation with a 575 nm pulse. The stretching mode of NO in Mb<SUP>III</SUP>NO consists of a major band at 1922 cm<SUP>–1</SUP> (97.7%) and a minor band at 1902 cm<SUP>–1</SUP> (2.3%), suggesting that Mb<SUP>III</SUP>NO in room temperature solution has two conformational substates. The time-resolved spectra show small but significant new absorption features at the lower-energy side of the main band (1920–1800 cm<SUP>–1</SUP>). One new absorption feature in the region of 1920–1880 cm<SUP>–1</SUP> exhibits the <SUP>15</SUP>NO isotope shift (37 cm<SUP>–1</SUP>) the same as that of the NO band in the ground electronic state of Mb<SUP>III</SUP>NO. This absorption shifts toward higher energy and narrows with a time constant of 2.4 ps, indicating that it evolves with rapid electronic and thermal relaxation of the photoexcited Mb<SUP>III</SUP>NO without photodeligation of the NO from the heme. Absorption features assigned to proteins undergoing thermal relaxation without NO deligation add up to 14 ± 1% of the total bleach, implying that the photolysis quantum yield of Mb<SUP>III</SUP>NO with a Q-band excitation is ≤0.86 ± 0.01. The remaining absorption bands peaked near 1867, 1845, and 1815 cm<SUP>–1</SUP>, each showing the <SUP>15</SUP>NO isotope shift the same as that of the free NO radical (33 cm<SUP>–1</SUP>), were assigned to the vibrational band of the photodeligated NO, the NO band of Mb<SUP>III</SUP>NO in an intermediate electronic state with low-spin Fe(III)–NO(radical) character (denoted as the R state), and the NO band of the vibrationally excited NO in the R state, respectively. A kinetics model successfully reproducing the time-dependent intensity changes of the transient bands suggests that every rebound NO forms the R state that eventually relaxes into the ground electronic state nonexponentially. Most of the photodissociated NO undergoes fast geminate recombination (GR), and the rebinding kinetics depends on the conformation of the protein. GR of NO to Mb<SUP>III</SUP> in the major conformation shows highly nonexponential kinetics described by a stretched exponential function, exp(−(<I>t</I>/290 ps)<SUP>0.44</SUP>. The NO rebinding to Mb<SUP>III</SUP> in the minor conformation is exponential, exp(−<I>t</I>/1.8 ns), suggesting that the distal histidine, the interaction of which dictates the conformation of Mb<SUP>III</SUP>NO, participates in mediating the binding of NO to Mb<SUP>III</SUP>. In Mb<SUP>III</SUP>NO, the elusive low-spin Fe(III)–NO(radical) state, proposed in electronic structure calculations, indeed exists at >12 kJ/mol above the ground state and takes part in the bond formation of Fe(III)–NO, suggesting that it plays a significant role in the function of NO-bound ferric protein. Time-resolved vibrational spectra with high sensitivity reveal rich photophysical and photochemical processes of photoexcited Mb<SUP>III</SUP>NO.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcbfk/2013/jpcbfk.2013.117.issue-10/jp400055d/production/images/medium/jp-2013-00055d_0013.gif'></P>
Park Cheol,Cha Hee-Jae,Kim Da Hye,Kwon Chan-Young,Park Shin-Hyung,Hong Su Hyun,Bang EunJin,Cheong Jaehun,Kim Gi-Young,Choi Yung Hyun 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.5
Fisetin is a bioactive flavonol molecule and has been shown to have antioxidant potential, but its efficacy has not been fully validated. The aim of the present study was to investigate the protective efficacy of fisetin on C2C12 murine myoblastjdusts under hydrogen peroxide (H2O2)-induced oxidative damage. The results revealed that fisetin significantly weakened H2O2-induced cell viability inhibition and DNA damage while blocking reactive oxygen species (ROS) generation. Fisetin also significantly alleviated cell cycle arrest by H2O2 treatment through by reversing the upregulation of p21WAF1/CIP1 expression and the downregulation of cyclin A and B levels. In addition, fisetin significantly blocked apoptosis induced by H2O2 through increasing the Bcl-2/Bax ratio and attenuating mitochondrial damage, which was accompanied by inactivation of caspase-3 and suppression of poly(ADP-ribose) polymerase cleavage. Furthermore, fisetin-induced nuclear translocation and phosphorylation of Nrf2 were related to the increased expression and activation of heme oxygenase-1 (HO-1) in H2O2- stimulated C2C12 myoblasts. However, the protective efficacy of fisetin on H2O2-mediated cytotoxicity, including cell cycle arrest, apoptosis and mitochondrial dysfunction, were greatly offset when HO-1 activity was artificially inhibited. Therefore, our results indicate that fisetin as an Nrf2 activator effectively abrogated oxidative stress-mediated damage in C2C12 myoblasts.