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961.
962.
Miyuki Sakaguchi Kyoko Shinzawa-Itoh Shinya Yoshikawa Takashi Ogura 《Journal of bioenergetics and biomembranes》2010,42(3):241-243
In the resting oxidized state (the fully oxidized “as-isolated” state) of cytochrome c oxidase (CcO) preparation, a resonance Raman band is observed at 755 cm-1 upon 647.1 nm excitation in resonance with an absorption band at 655 nm. Addition of cyanide eliminates the Raman band concomitant
with loss of the absorption band at 655 nm. These results strongly suggest that the Raman band at 755 cm-1 originates from the O−O stretching mode of the bridging peroxide (Fe−O-−O-−Cu) in the O2 reduction site of the fully oxidized “as-isolated” CcO. Although the peroxide bridged structure has been proposed on the basis of X-ray crystallography and reductive titration
experiments, the present vibrational spectroscopic analyses reveal conclusively the chemical nature of the bridging ligand
at the O2 reduction site of the fully oxidized “as-isolated” bovine heart CcO. 相似文献
963.
Morio Miyahara Sang-Wan Kim Shinya Fushinobu Koki Takaki Takeshi Yamada Akira Watanabe Keisuke Miyauchi Ginro Endo Takayoshi Wakagi Hirofumi Shoun 《Applied and environmental microbiology》2010,76(14):4619-4625
In contrast to most denitrifiers studied so far, Pseudomonas stutzeri TR2 produces low levels of nitrous oxide (N2O) even under aerobic conditions. We compared the denitrification activity of strain TR2 with those of various denitrifiers in an artificial medium that was derived from piggery wastewater. Strain TR2 exhibited strong denitrification activity and produced little N2O under all conditions tested. Its growth rate under denitrifying conditions was near comparable to that under aerobic conditions, showing a sharp contrast to the lower growth rates of other denitrifiers under denitrifying conditions. Strain TR2 was tolerant to toxic nitrite, even utilizing it as a good denitrification substrate. When both nitrite and N2O were present, strain TR2 reduced N2O in preference to nitrite as the denitrification substrate. This bacterial strain was readily able to adapt to denitrifying conditions by expressing the denitrification genes for cytochrome cd1 nitrite reductase (NiR) (nirS) and nitrous oxide reductase (NoS) (nosZ). Interestingly, nosZ was constitutively expressed even under nondenitrifying, aerobic conditions, consistent with our finding that strain TR2 preferred N2O to nitrite. These properties of strain TR2 concerning denitrification are in sharp contrast to those of well-characterized denitrifiers. These results demonstrate that some bacterial species, such as strain TR2, have adopted a strategy for survival by preferring denitrification to oxygen respiration. The bacterium was also shown to contain the potential to reduce N2O emissions when applied to sewage disposal fields.Wastewater treatment processes produce one of the major greenhouse effect gases, nitrous oxide (N2O) (7, 25, 30). The global warming potential of N2O relative to that of carbon dioxide (CO2) is 298 for a 100-year time horizon, and its concentration in the atmosphere continues to increase by about 0.26% per year (9). Nitrogen removal in wastewater treatment plants is essentially based on the activities of nitrifying and denitrifying microorganisms, both of which are inhabitants of activated sludge. Nitrifying bacteria aerobically oxidize ammonium to nitrite (NO2−) and nitrate (NO3−), which are then reduced anaerobically by denitrifying bacteria to gaseous nitrogen forms, such as N2O and dinitrogen (N2). It has long been known that N2O can be produced during both nitrification and denitrification processes of wastewater treatment (3, 19, 23), but the cause of N2O emission during the nitrification process was not clear. We recently showed, however, using activated sludge grown under conditions that mimicked a piggery wastewater disposal, that N2O emission during the nitrification process depends on denitrification by ammonia-oxidizing bacteria (Nitrosomonas) (18). On the other hand, it is believed that denitrifying bacteria produce N2O as a by-product when anaerobiosis is insufficient during the denitrification process, because N2O reductase is the enzyme that is most sensitive to oxygen (6). Piggery wastewater, in particular, contains a high concentration of ammonia, and N2O emission tends to take place during the nitrogen removal process (5, 10). Experiments on the removal of ammonia and organic carbon by the aerobic denitrifier Pseudomonas stutzeri SU2 (24) and the heterotrophic nitrifier-aerobic denitrifier Alcaligenes faecalis no. 4 (16, 17) have been reported as examples of bioaugmentation in piggery wastewater treatment. Reduction of N2O emissions from pig manure compost by addition of nitrite-oxidizing bacteria has also been reported (11). However, there have been no reports of methods for reducing N2O emissions by bioaugmentation using aerobic denitrifying bacteria.Takaya et al. isolated the aerobic denitrifying bacterium Pseudomonas stutzeri TR2 (26). The denitrification activity of strain TR2 was monitored in batch and continuous cultures, using denitrification and artificial wastewater media, and the strain was found to keep a distinct activity (producing N2 from NO3−) and to produce a very low level of N2O at a dissolved oxygen (O2) concentration of 1.25 mg liter−1. Therefore, strain TR2 should be useful in the future for reducing N2O emissions from wastewater treatment plants by bioaugmentation. To investigate the feasibility of using strain TR2 for future application to wastewater treatment processes, we examined its denitrification activity, N2O production, growth rate, and expression of denitrifying genes in batch cultures, using a medium that mimics the composition found in nitrogen removal wastewater plants. Comparison of the properties of strain TR2 with those of well-characterized denitrifying bacteria revealed characteristics of the strain that favor denitrification, although it can also respire oxygen. 相似文献
964.
Takuya Koseki Keiji Mochizuki Hiroe Kisara Akimasa Miyanaga Shinya Fushinobu Tetsuya Murayama Yoshihito Shiono 《Applied microbiology and biotechnology》2010,86(1):155-161
We engineered a chimeric enzyme (AwFaeA-CBM42) comprising of type-A feruloyl esterase from Aspergillus awamori (AwFaeA) and family 42 carbohydrate-binding module (AkCBM42) from glycoside hydrolase family 54 α-l-arabinofuranosidase of Aspergillus kawachii. The chimeric enzyme was successfully produced in Pichia pastoris and accumulated in the culture broth. The purified chimeric enzyme had an apparent relative molecular mass (M
r) of 53,000. The chimeric enzyme binds to arabinoxylan; this indicates that the AkCBM42 in AwFaeA-CBM42 binds to arabinofuranose
side chain moiety of arabinoxylan. The thermostability of the chimeric enzyme was greater than that of AwFaeA. No significant
difference of the specific activity toward methyl ferulate was observed between the AwFaeA and chimeric enzyme, but the release
of ferulic acid from insoluble arabinoxylan by the chimeric enzyme was approximately 4-fold higher than that achieved by AwFaeA
alone. In addition, the chimeric enzyme and xylanase acted synergistically for the degradation of arabinoxylan. In conclusion,
the findings of our study demonstrated that the components of the AwFaeA-CBM42 chimeric enzyme act synergistically to bring
about the degradation of complex substrates and that the family 42 carbohydrate-binding module has potential for application
in the degradation of polysaccharides. 相似文献
965.
Noriko Sumi Tsuyoshi Nishioku Fuyuko Takata Junichi Matsumoto Takuya Watanabe Hideki Shuto Atsushi Yamauchi Shinya Dohgu Yasufumi Kataoka 《Cellular and molecular neurobiology》2010,30(2):247-253
The blood–brain barrier (BBB) is formed by brain capillary endothelial cells, astrocytes, pericytes, microglia, and neurons.
BBB disruption under pathological conditions such as neurodegenerative disease and inflammation is observed in parallel with
microglial activation. To test whether activation of microglia is linked to BBB dysfunction, we evaluated the effect of lipopolysaccharide
(LPS) on BBB functions in an in vitro co-culture system with rat brain microvascular endothelial cells (RBEC) and microglia.
When LPS was added for 6 h to the abluminal side of RBEC/microglia co-culture at a concentration showing no effects on the
RBEC monolayer, transendothelial electrical resistance was decreased and permeability to sodium-fluorescein was increased
in RBEC. Immunofluorescence staining for tight junction proteins demonstrated that zonula occludens-1-, claudin-5-, and occludin-like
immunoreactivities at the intercellular borders of RBEC were fragmented in the presence of LPS-activated microglia. These
functional changes induced by LPS-activated microglia were blocked by the nicotinamide adenine dinucleotide phosphate (NADPH)
oxidase inhibitor, diphenyleneiodonium chloride. The present findings suggest that LPS activates microglia to induce dysfunction
of the BBB by producing reactive oxygen species through NADPH oxidase. 相似文献
966.
Yuou Teng Katsuya Iuchi Eriko Iwasa Shinya Fujishiro Yoshitaka Hamashima Kosuke Dodo Mikiko Sodeoka 《Bioorganic & medicinal chemistry letters》2010,20(17):5085-5088
Chaetocin, a natural product isolated from Chaetomium species fungi, was reported to have various biological activities, including antitumor and antifungal activities. Recently, we reported the first total synthesis of chaetocin and its derivatives. Here, we examined the cell-death-inducing activity of these compounds in human leukemia HL-60 cells. The unnatural enantiomer of chaetocin (ent-chaetocin) was more potent than chaetocin, and was found to induce apoptosis through the caspase-8/caspase-3 activation pathway. 相似文献
967.
Mikihiro Yunoki Hiroyuki Tanaka Takeru Urayama Yuta Kanai Aya Nishida Maki Yoshikawa Yuji Ohkubo Yoshiyasu Kawabata Katsuro Hagiwara Kazuyoshi Ikuta 《Biologicals》2010,38(2):311-313
The evaluation of the removal efficacy during manufacturing is important for the risk assessment of plasma products with respect to possible contamination by infectious prions, as recently reported in several papers on the potential for prion transmission through plasma products. Here, we evaluated a virus removal filter which has 15 nm pores. An antithrombin sample immediately prior to nano-filtration was spiked with prion material prepared in two different ways. The removal (log reduction factor) of prion infectivity using animal bioassays was ≥4.72 and 4.00 in two independent filtrations. However, infectivity was detected in both the pellet and supernatant following ultracentrifugation of the 15 nm filtered samples, indicating difficulty in complete removal. The data supports the conclusion that a certain amount of infectious prion protein is present as a smaller and/or soluble form (less than ~15 nm in diameter). 相似文献
968.
Takagi T Naito Y Uchiyama K Yoshikawa T 《Redox report : communications in free radical research》2010,15(5):193-201
Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease, is a chronic and recurrent inflammatory disorder of the intestinal tract. Since the precise pathogenesis of IBD remains unclear, it is important to investigate the pathogenesis of IBD and to evaluate new anti-inflammatory strategies. Recent evidence suggests that heme oxygenase-1 (HO-1) plays a critical protective role during the development of intestinal inflammation. In fact, it has been demonstrated that the activation of HO-1 may act as an endogenous defensive mechanism to reduce inflammation and tissue injury in various animal intestinal injury models induced by ischemia-reperfusion, indomethacin, lipopolysaccharide-associated sepsis, trinitrobenzene sulfonic acid or dextran sulfate sodium. In addition, carbon monoxide (CO) derived from HO-1 has been shown to be involved in the regulation of intestinal inflammation. Furthermore, administration of a low concentration of exogenous CO has a protective effect against intestinal inflammation. These data suggest that HO-1 and CO may be novel therapeutic molecules for patients with gastrointestinal inflammatory diseases. In this review, we present what is currently known regarding the role of HO-1 and CO in intestinal inflammation. 相似文献
969.
Takashi Asahi Hajime Kondo Mitsuharu Masuda Hoyoku Nishino Yasuaki Aratani Yuji Naito Toshikazu Yoshikawa Shinsuke Hisaka Yoji Kato Toshihiko Osawa 《The Journal of biological chemistry》2010,285(12):9282-9291
Myeloperoxidase (MPO) generates reactive halogenating species that can modify DNA. The aim of this study was to investigate the formation of 8-halogenated 2′-deoxyguanosines (8- halo-dGs) during inflammatory events. 8-Bromo-2′-dG (8-BrdG) and 8-chloro-2′-dG (8-CldG) were generated by treatment of MPO with hydrogen peroxide at physiological concentrations of Cl− and Br−. The formation of 8-halo-dGs with other oxidative stress biomarkers in lipopolysaccharide-treated rats was assessed by liquid chromatography tandem mass spectrometry and immunohistochemistry using a novel monoclonal antibody (mAb8B3) to 8-BrdG-conjugated keyhole limpet hemocyanin. The antibody recognized both 8-BrdG and 8-CldG. In the liver of lipopolysaccharide-treated rats, immunostaining for 8-halo-dGs, halogenated tyrosines, and MPO were increased at 8 h, whereas those of 8-oxo-2′-dG (8-OxodG) and 3-nitrotyrosine were increased at 24 h. Urinary excretion of both 8-CldG and 8-BrdG was also observed earlier than those of 8-OxodG and modified tyrosines (3-nitrotyrosine, 3-chlorotyrosine, and 3- bromotyrosine). Moreover, the levels of the 8-halo-dGs in urine from human diabetic patients were 8-fold higher than in healthy subjects (n = 10, healthy and diabetic, p < 0.0001), whereas there was a moderate difference in 8-OxodG between the two groups (p < 0.001). Interestingly, positive mAb8B3 antibody staining was observed in liver tissue from hepatocellular carcinoma patients but not in liver tissue from human cirrhosis patients. These data suggest that 8-halo-dGs may be potential biomarkers of early inflammation. 相似文献
970.
Chiharu Fujihara Satoru Yamada Nobuhiro Ozaki Nobuo Takeshita Harumi Kawaki Teruko Takano-Yamamoto Shinya Murakami 《The Journal of biological chemistry》2010,285(36):28286-28297
In this study, we analyzed the effects of tensile mechanical stress on the gene expression profile of in vitro-maintained human periodontal ligament (PDL) cells. A DNA chip analysis identified 17 up-regulated genes in human PDL cells under the mechanical stress, including HOMER1 (homer homolog 1) and GRIN3A (glutamate receptor ionotropic N-methyl-d-aspartate 3A), which are related to glutamate signaling. RT-PCR and real-time PCR analyses revealed that human PDL cells constitutively expressed glutamate signaling-associated genes and that mechanical stress increased the expression of these mRNAs, leading to release of glutamate from human PDL cells and intracellular glutamate signal transduction. Interestingly, exogenous glutamate increased the mRNAs of cytodifferentiation and mineralization-related genes as well as the ALP (alkaline phosphatase) activities during the cytodifferentiation of the PDL cells. On the other hand, the glutamate signaling inhibitors riluzole and (+)-MK801 maleate suppressed the alkaline phosphatase activities and mineralized nodule formation during the cytodifferentiation and mineralization. Riluzole inhibited the mechanical stress-induced glutamate signaling-associated gene expressions in human PDL cells. Moreover, in situ hybridization analyses showed up-regulation of glutamate signaling-associated gene expressions at tension sites in the PDL under orthodontic tooth movement in a mouse model. The present data demonstrate that the glutamate signaling induced by mechanical stress positively regulates the cytodifferentiation and mineralization of PDL cells. 相似文献