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991.
Jaya Ram Simkhada Seung Sik Cho Hong Seok Choi Si Wouk Kim Hei Chan Lee Jae Kyung Sohng Jin Cheol Yoo 《Biotechnology and Bioprocess Engineering》2010,15(4):595-602
A phospholipase D (PLD628), constitutively secreted by Streptomyces sp. CS628, was purified by ion exchange with CM Trisacryl and gel filtration with Sepharose CL-6B. The enzyme production
was highest with peptone and starch as nitrogen and carbon sources, and at 30°C with an initial medium pH of 7.5. Molecular
weight, optimum pH, optimum temperature, pH stability, and thermostability of the enzyme were 50 kDa, pH 9.6, 30°C, pH 5.7
∼ 10.6 and ≤30°C, respectively. Detergents and metal ions had varied effects on the enzyme activity. Importantly, PLD628 could not catalyze transphosphatidylation of glycerol, L-serine, myo-inositol or ethanolamine, which are extensively used to assess the activity, suggesting that PLD628 lacks the transphosphatidylation activity. PLD628 could be a novel PLD based on its biochemical characteristics, which are significantly different from previously reported
PLDs, such as thermolability, highest activity at alkaline pH, and lack of transphosphatidylation activity. 相似文献
992.
G. Satheesh kumar M. Subhosh Chandra K. V. Mallaiah P. Sreenivasulu Yong-Lark Choi 《Biotechnology and Bioprocess Engineering》2010,15(3):435-440
In this study, the production of extracellular thermostable α-amylase by newly isolated thermophilic Alicyclobacillus acidocaldarius was detected on LB agar plates containing 1.0% soluble potato starch and incubated at 60°C. This extracellular α-amylase
was purified to homogeneity by ammonium sulphate precipitation followed by Sephadex and ion-exchange chromatography. The α-amylase
was purified to 8.138 fold homogeneity with a final recovery of 58% and a specific activity of 3,239 U/mg proteins. The purified
α-amylase appeared as a single protein band on SDS-PAGE with a molecular mass of 94.5 kDa. Non-denaturing PAGE analysis showed
one major band associated with enzyme activity, indicating the absence of isoenzymes. A TLC analysis showed maltose as major
end product of the enzyme. The optimum assay temperature and pH for enzyme activity were 60°C and 6.0 respectively; however,
the enzyme activity was stable over a wide range of pH and temperatures. The α-amylase retained its activity in the presence
of the denaturing agents — SDS, Triton X-100, Tween-20, Tween-80, and was significantly inhibited by EDTA and urea. Calcium
ions increased the enzyme activity, while Hg2+, Zn2+, and Co2+ had inhibitory effects. The K
m and V
max values were found to be 2.9 mg/mL and 7936 U/mL respectively. 相似文献
993.
Mi Jin Yoon Eun Hee Kim Jun Hee Lim Taeg Kyu Kwon Kyeong Sook Choi 《Free radical biology & medicine》2010,48(5):713-726
Curcumin is considered a pharmacologically safe agent that may be useful in cancer chemoprevention and therapy. Here, we show for the first time that curcumin effectively induces paraptosis in malignant breast cancer cell lines, including MDA-MB-435S, MDA-MB-231, and Hs578T cells, by promoting vacuolation that results from swelling and fusion of mitochondria and/or the endoplasmic reticulum (ER). Inhibition of protein synthesis by cycloheximide blocked curcumin-induced vacuolation and subsequent cell death, indicating that protein synthesis is required for this process. The levels of AIP-1/Alix protein, a known inhibitor protein of paraptosis, were progressively downregulated in curcumin-treated malignant breast cancer cells, and AIP-1/Alix overexpression attenuated curcumin-induced death in these cells. ERK2 and JNK activation were positively associated with curcumin-induced cell death. Mitochondrial superoxide was shown to act as a critical early signal in curcumin-induced paraptosis, whereas proteasomal dysfunction was mainly responsible for the paraptotic changes associated with ER dilation. Notably, curcumin-induced paraptotic events were not observed in normal breast cells, including mammary epithelial cells and MCF-10A cells. Taken together, our findings on curcumin-induced paraptosis may provide novel insights into the mechanisms underlying the selective anti-cancer effects of curcumin against malignant cancer cells. 相似文献
994.
Shin-Young Park Ju Hwan Cho Weina Ma Hye-Jin Choi Joong-Soo Han 《Cellular signalling》2010,22(4):619-628
The purpose of this study was to identify the role of phospholipase D2 (PLD2) in lipopolysaccharide (LPS)-induced nitric oxide (NO) synthesis. LPS enhanced NO synthesis and inducible nitric oxide synthase (iNOS) expression in macrophage cell line, Raw 264.7 cells. When Raw 264.7 cells were stimulated with LPS, the expressions of PLDs were increased. Thus, to investigate the role of PLD in NO synthesis, we transfected PLD1, PLD2, and their dominant negative forms to Raw 264.7 cells, respectively. Interestingly, only PLD2 overexpression, but not that of PLD1, increased NO synthesis and iNOS expression. Moreover, LPS-induced NO synthesis and iNOS expression were blocked by PLD2 siRNA, suggesting that LPS upregulates NO synthesis through PLD2. Next, we investigated the S6K1-p42/44 MAPK-STAT3 signaling pathway in LPS-induced NO synthesis mechanism. Knockdown of PLD2 with siRNA also decreased phosphorylation of S6K1, p42/44 MAPK and STAT3 induced by LPS. Furthermore, we found that STAT3 bound with the iNOS promoter, and their binding was mediated by PLD2. Taken together, our results demonstrate the importance of PLD2 for LPS-induced NO synthesis in Raw 264.7 cells with involvement of the S6K1-p42/44 MAPK-STAT3 pathway. 相似文献
995.
Hyun-Jeong Kwak Kyoung-Mi Park Hye-Eun Choi Hyun-Joung Lim Jin-Hee Park Hyun-Young Park 《Cellular signalling》2010,22(1):80-87
Zileuton has been demonstrated to act as an anti-inflammatory agent by virtue of its well-known ability to inhibit 5-lipoxygenase (5-LO). However, the effects of zileuton on cardiovascular disease and cardiomyocyte apoptosis are unclear. Here, we investigated the effects of zileuton on apoptosis of cardiac myogenic H9c2 cells and neonatal rat cardiomyocytes (NRCMs), and examined the possible role of PKCδ-mediated induction of COX-2 in these effects. Treatment of H9c2 cells with zileuton efficiently induced COX-2 expression and PGE2 biosynthesis in a time- and dose-dependent manner. Zileuton also exerted a profound protective effect against H2O2-induced oxidative stress, a mimic of reperfusion damage in vitro, and this protective effect was abolished by COX-2-selective inhibitor. When we investigated the signalling pathways involved in zileuton-induced COX-2 expression, we found that zileuton acts as a PKCδ activator, causing it to translocate from the cytosol to nucleus. Inhibition of PKCδ activation with rottlerlin, a PKCδ-specific inhibitor, abolished the zileuton-induced protection against H2O2-induced cell death and inhibited zileuton-induced COX-2 expression and PGE2 production. The protective effect of zileuton was dramatically diminished by treatment with LY294002 or PD98059. Furthermore, zileuton-stimulated ERK1/2 and Akt phosphorylation was attenuated by rottlerin, indicating that PKCδ might act upstream of ERK1/2 and Akt. Moreover, inhibition of either ERK1/2 or Akt activation abolished zileuton-induced COX-2 expression. Knockdown of PKCδ with siRNA also reversed the protective effect of zileuton and blocked the induction of COX-2. These results suggest that zileuton-induced COX-2 expression is sequentially mediated through PKCδ-dependent activation of ERK1/2 and Akt. Based on these findings, we propose that zileuton might provide a new therapeutic strategy for ischemia/reperfusion injury of the heart. 相似文献
996.
Jung Woong Choi Seyoung Lim Yong-Seok Oh Eung-Kyun Kim Sun-Hee Kim Yun-Hee Kim Kyun Heo Jaeyoon Kim Jung Kuk Kim Yong Ryul Yang Sung Ho Ryu Pann-Ghill Suh 《Cellular signalling》2010,22(7):1153-1161
Among phospholipase C (PLC) isozymes (β, γ, δ, ε, ζ and η), PLC-β plays a key role in G-protein coupled receptor (GPCR)-mediated signaling. PLC-β subtypes are often overlapped in their distribution, but have unique knock-out phenotypes in organism, suggesting that each subtype may have the different role even within the same type of cells. In this study, we examined the possibility of the differential coupling of each PLC-β subtype to GPCRs, and explored the molecular mechanism underlying the specificity. Firstly, we found that PLC-β1 and PLC-β3 are activated by bradykinin (BK) or lysophosphatidic acid (LPA), respectively. BK-triggered phosphoinositides hydrolysis and subsequent Ca2+ mobilization were abolished specifically by PLC-β1 silencing, whereas LPA-triggered events were by PLC-β3 silencing. Secondly, we showed the evidence that PDZ scaffold proteins is a key mediator for the selective coupling between PLC-β subtype and GPCR. We found PAR-3 mediates physical interaction between PLC-β1 and BK receptor, while NHERF2 does between PLC-β3 and LPA2 receptor. Consistently, the silencing of PAR-3 or NHERF2 blunted PLC signaling induced by BK or LPA respectively. Taken together, these data suggest that each subtype of PLC-β is selectively coupled to GPCR via PDZ scaffold proteins in given cell types and plays differential role in the signaling of various GPCRs. 相似文献
997.
Sul OJ Kim JC Kyung TW Kim HJ Kim YY Kim SH Kim JS Choi HS 《Bioscience, biotechnology, and biochemistry》2010,74(11):2209-2213
Gold nanoparticles inhibited osteoclast (OC) formation induced by the receptor activator of nuclear factor-κB ligand (RANKL) in bone marrow-derived macrophages (BMMs). This was accompanied by a decreased level of tartrate-resistant alkaline phosphatase (TRAP) and less activation of nuclear factor (NF)-κB. The nanoparticles also reduced the production of reactive oxygen species (ROS) in response to RANKL and upregulated RANKL-induced glutathione peroxidase-1 (Gpx-1), suggesting a role as an antioxidant in the BMM. The inhibitory effects on OC formation might have been due to elevated defense against oxidative stress. 相似文献
998.
A novel approach CE-Ploc is proposed for predicting protein subcellular locations by exploiting diversity both in feature and decision spaces. The
diversity in a sequence of feature spaces is exploited using hydrophobicity and hydrophilicity of amphiphilic pseudo amino
acid composition and a specific learning mechanism. Diversity in learning mechanisms is exploited by fusion of classifiers
that are based on different learning mechanisms. Significant improvement in prediction performance is observed using jackknife
and independent dataset tests. 相似文献
999.