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191.
Biofuel cell system employing thermostable glucose dehydrogenase 总被引:1,自引:0,他引:1
Okuda-Shimazaki J Kakehi N Yamazaki T Tomiyama M Sode K 《Biotechnology letters》2008,30(10):1753-1758
Enzyme biofuel cells utilizing glucose dehydrogenase as an anode enzyme were constructed. The glucose dehydrogenase is composed of a catalytic subunit, an electron transfer subunit, and a chaperon-like subunit. Cells, constructed using either a glucose dehydrogenase catalytic subunit or a glucose dehydrogenase complex, displayed power outputs that were dependent on the glucose concentration. The catalytic subunit in the anode maintained its catalytic activity for 24 h of operation. The biofuel cell which composed of glucose dehydrogenase complex functioned successfully even in the absence of an electron mediator at the anode cell. These results indicate the potential application of this thermostable glucose dehydrogenase for the construction of a compartment-less biofuel cell. 相似文献
192.
Extracellular superoxide released from mitochondria mediates mast cell death by advanced glycation end products 总被引:1,自引:0,他引:1
Advanced glycation end products (AGEs) accumulate during aging and to higher extents under pathological conditions such as diabetes. Since we previously showed that mast cells expressed the AGE-binding protein, receptor for AGEs (RAGE) on their cell surface, we examined whether AGE affected mast cell survival. Herein, we demonstrate that mast cells undergo apoptosis in response to AGE. Glycated albumin (GA), an AGE, but not stimulation with the high-affinity IgE receptor (FcepsilonRI), can induce mast cell death, as measured by annexin V/propidium iodide double-staining. GA (> or =0.1 mg/ml) exhibited this pro-apoptotic activity in a concentration-dependent manner. GA and FcepsilonRI stimulation increased the cytosolic Ca(2+) levels to a similar extent, whereas GA, but not FcepsilonRI stimulation, caused mitochondrial Ca(2+) overload and membrane potential collapse, resulting in mitochondrial integrity disruption, cytochrome c release and caspase-3/7 activation. In addition, GA, but not FcepsilonRI stimulation, induced extracellular release of superoxide from mitochondria, and this release played a key role in the disruption of Ca(2+) homeostasis. Knockdown of RAGE expression using small interfering RNA abolished GA-induced apoptosis, mitochondrial Ca(2+) overload, and superoxide release, demonstrating that RAGE mediates the GA-induced mitochondrial death pathway. AGE-induced mast cell apoptosis may contribute to the immunocompromised and inflammatory conditions. 相似文献
193.
In the RecFOR pathway, the RecF and RecR proteins form a complex that binds to DNA and exerts multiple functions, including directing the loading of RecA onto single-stranded (ss) DNA regions near double-stranded (ds) DNA–ssDNA junctions and preventing it from forming a filament beyond the ssDNA region. However, neither the structure of the RecFR complex nor its DNA-binding mechanism was previously identified. Here, size-exclusion chromatography and small-angle X-ray scattering data indicate that Thermus thermophilus (tt) RecR binds to ttRecF to form a globular structure consisting of four ttRecR and two ttRecF monomers. In addition, a low resolution model shows a cavity in the central part of the complex, suggesting that ttRecR forms a ring-like tetramer inside the ttRecFR complex. Mutant ttRecR proteins lacking the N- or C-terminal interfaces that are required for tetramer formation are unable to form a complex with ttRecF. Furthermore, a ttRecFR complex containing the DNA-binding deficient ttRecR K23E/R27E double mutant, which contains mutations lying inside the ring, exhibits significantly reduced dsDNA binding. Thus, we propose that the ring-like ttRecR tetramer has a key role in tethering the ttRecFR complex onto dsDNA and that the ring structure may function as a clamp protein. 相似文献
194.
Naruishi K Omori K Maeda H Sonoi N Funakoshi K Hirai K Ishii M Kubo K Kobayashi H Tomiyama T Yamamoto D Tanimoto I Kunimatsu K Takashiba S 《Journal of biological regulators and homeostatic agents》2011,25(2):195-202
Periodontitis is a localized infectious disease caused by periodontopathic bacteria such as Porphyromonas gingivalis (P. gingivalis), and the severity correlates to significance of immune responses. Recently, it has been reported that periodontitis is associated with the development of systemic disease such as diabetes and atherosclerosis because of increasing invasion of oral pathogens to the circulation. However, the association between local and systemic infectious responses is still unclear. In the present study, we examined the differences of biological responses in animals with or without bacterial infection. After Balb/c mice were infected subcutaneously with live P. gingivalis W83, serum, skin and liver were collected according to experimental protocol. The skin and liver tissues were observed pathologically by haematoxylin-eosin staining, and serum IL-6 levels were measured using ELISA method. Throughout the experimental period, conditions of the mice were observed continuously. As expected, severe infiltration of leukocytes were observed at inflamed skin corresponding to the number of bacterial challenges. Although no inflammatory appearance of skin was observed, serum IL-6 levels were increased dramatically (P <0.01, Student's t-test) and liver tissues were injured in the mice without bacterial challenge. Interestingly, although severe inflammatory appearance of the skin was observed, serum IL-6 levels were not increased and no inflammatory responses were observed in the liver of the 3-times bacterially challenged group. Importantly, immunoglobulin G against P. gingivalis W83 was detected in the blood of mice with 3-times bacterial challenge corresponding to improvement of weight loss and survival. In conclusion, although multiple infections develop severe localized inflammation, the immune system should be sufficient to protect the systemic inflammatory responses. 相似文献
195.
Tatsuaki Goh Hiroyuki Kasahara Tetsuro Mimura Yuji Kamiya Hidehiro Fukaki 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2012,367(1595):1461-1468
In Arabidopsis thaliana, lateral root (LR) formation is regulated by multiple auxin/indole-3-acetic acid (Aux/IAA)–AUXIN RESPONSE FACTOR (ARF) modules: (i) the IAA28–ARFs module regulates LR founder cell specification; (ii) the SOLITARY-ROOT (SLR)/IAA14–ARF7–ARF19 module regulates nuclear migration and asymmetric cell divisions of the LR founder cells for LR initiation; and (iii) the BODENLOS/IAA12–MONOPTEROS/ARF5 module also regulates LR initiation and organogenesis. The number of Aux/IAA–ARF modules involved in LR formation remains unknown. In this study, we isolated the shy2-101 mutant, a gain-of-function allele of short hypocotyl2/suppressor of hy2 (shy2)/iaa3 in the Columbia accession. We demonstrated that the shy2-101 mutation not only strongly inhibits LR primordium development and emergence but also significantly increases the number of LR initiation sites with the activation of LATERAL ORGAN BOUNDARIES-DOMAIN16/ASYMMETRIC LEAVES2-LIKE18, a target gene of the SLR/IAA14–ARF7–ARF19 module. Genetic analysis revealed that enhanced LR initiation in shy2-101 depended on the SLR/IAA14–ARF7–ARF19 module. We also showed that the shy2 roots contain higher levels of endogenous IAA. These observations indicate that the SHY2/IAA3–ARF-signalling module regulates not only LR primordium development and emergence after SLR/IAA14–ARF7–ARF19 module-dependent LR initiation but also inhibits LR initiation by affecting auxin homeostasis, suggesting that multiple Aux/IAA–ARF modules cooperatively regulate the developmental steps during LR formation. 相似文献
196.
Akira Mine Kiwamu Hyodo Yuri Tajima Kusumawaty Kusumanegara Takako Taniguchi Masanori Kaido Kazuyuki Mise Hisaaki Taniguchi Tetsuro Okuno 《Journal of virology》2012,86(22):12091-12104
Assembly of viral replicase complexes of eukaryotic positive-strand RNA viruses is a regulated process: multiple viral and host components must be assembled on intracellular membranes and ordered into quaternary complexes capable of synthesizing viral RNAs. However, the molecular mechanisms underlying this process are poorly understood. In this study, we used a model virus, Red clover necrotic mosaic virus (RCNMV), whose replicase complex can be detected readily as the 480-kDa functional protein complex. We found that host heat shock proteins Hsp70 and Hsp90 are required for RCNMV RNA replication and that they interact with p27, a virus-encoded component of the 480-kDa replicase complex, on the endoplasmic reticulum membrane. Using a cell-free viral translation/replication system in combination with specific inhibitors of Hsp70 and Hsp90, we found that inhibition of p27-Hsp70 interaction inhibits the formation of the 480-kDa complex but instead induces the accumulation of large complexes that are nonfunctional in viral RNA synthesis. In contrast, inhibition of p27-Hsp90 interaction did not induce such large complexes but rendered p27 incapable of binding to a specific viral RNA element, which is a critical step for the assembly of the 480-kDa replicase complex and viral RNA replication. Together, our results suggest that Hsp70 and Hsp90 regulate different steps in the assembly of the RCNMV replicase complex. 相似文献
197.
Adachi T Teramachi M Yasuda H Kamiya T Hara H 《Archives of biochemistry and biophysics》2012,520(1):30-35
Diabetic retinopathy (DR) is characterized by the development of intraretinal microvascular abnormalities. Endoplasmic reticulum (ER) stress is known to play a pathogenic role in vascular impairment in DR. The present study demonstrated that the treatment of human retinal endothelial cells with ER stress inducers such as thapsigargin (Tg) and tunicamycin (Tm) significantly increased the permeability of exogenously added FITC-dextran, accompanied by a decrease of transendothelial electrical resistance (TEER). The expression of claudin-5 among tight junction proteins was significantly decreased by the treatment with Tg or Tm. A p38 MAPK inhibitor, SB203580, and an NF-κB inhibitor, dexamethasone, significantly suppressed the Tg-induced down-regulation of claudin-5, decrease of TEER and leakage of added FITC-dextran. The translocation of NF-κB p65 subunit to the nucleus was also inhibited by the addition of SB203580 or dexamethasone. The effects of dexamethasone are thought to be due to the transrepression of the above signaling and direct regulation of claudin-5 gene. 相似文献
198.
Ozaki T Nakazawa M Yamashita T Sorimachi H Hata S Tomita H Isago H Baba A Ishiguro S 《Biochimica et biophysica acta》2012,1822(11):1783-1795
Mitochondrial μ-calpain initiates apoptosis-inducing factor (AIF)-dependent apoptosis in retinal photoreceptor degeneration. Mitochondrial μ-calpain inhibitors may represent therapeutic targets for the disease. Therefore, we sought to identify inhibitors of mitochondrial calpains and determine their effects in Royal College of Surgeons' (RCS) rats, an animal model of retinitis pigmentosa (RP). We synthesized 20-mer peptides of the C2-like (C2L) domain of μ-calpain. Two μ-calpain peptides N2 and N9 inhibited mitochondrial μ-calpain activity (IC(50); 892 and 498nM, respectively), but not other proteases. Western blotting showed that 50μM of both μ-calpain peptides caused specific degradation of mitochondrial μ-calpain. Three-dimensional structure of calpains suggested that the peptides N2 and N9 corresponded to the regions forming salt bridges between the protease core domain 2 and the C2L domain. We determined the inhibitory regions of μ-calpain peptides N2 and N9 using 10-mers, and one peptide, N2-10-2, inhibited the activity of mitochondrial μ-calpain (IC(50); 112nM). We next conjugated the peptide N2-10-2 to the C-terminal of HIV-1 tat (HIV), a cell-penetrating peptide. Using isolated rat liver mitochondria, 50μM HIV-conjugated μ-calpain N2-10-2 peptide (HIV-Nμ, IC(50); 285nM) significantly inhibited AIF truncation. The intravitreal injection of 20mM HIV-Nμ also prevented retinal photoreceptor apoptosis determined by TUNEL staining, and preserved retinal function assessed by electroretinography in RCS rats. Topical application of 40mM HIV-Nμ also prevented apoptosis of retinal photoreceptors in RCS rats. Our results demonstrate that HIV-Nμ, a peptide inhibitor of mitochondrial μ-calpain, offers a new modality for treating RP. 相似文献
199.
200.
Cells of Nitella axilliformis were made tonoplast-free by intracellularperfusion of media containing ethyleneglycol-bis-(ß-aminoethylether)N,N'-tetraaceticacid (EGTA). When the perfusion medium contained ADP as wellas ATP, the membrane hyperpolarized in darkness in a mannersimilar to light-induced hyperpolarization. This light-independenthyperpolarization seems to be due to activation of the electrogenicion pump in the plasma membrane because the hyperpolarized valueof the membrane potential was more negative than the equilibriumpotential for K$, the most negative ion equilibrium potentialin Nitella. The hyperpolarization was inhibited by the respiratory chaininhibitors NaCN (1 mM), antimycin A (10 µM) and rotenone(10 µM). NaCN slightly decreased the ATP concentrationin the cell perfused with medium containing 1 mM ATP and 1 mMADP; but, even after treatment with NaCN, the cell had about80% of the ATP value for the control.
* This study is dedicated to the late Professor J. Ashida. (Received June 24, 1982; Accepted October 15, 1982) 相似文献