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排序方式: 共有8428条查询结果,搜索用时 31 毫秒
971.
Zhang Y Ju J Peng H Gao F Zhou C Zeng Y Xue Y Li Y Henrissat B Gao GF Ma Y 《The Journal of biological chemistry》2008,283(46):31551-31558
An intracellular mannanase was identified from the thermoacidophile Alicyclobacillus acidocaldarius Tc-12-31. This enzyme is particularly interesting, because it shows no significant sequence similarity to any known glycoside hydrolase. Gene cloning, biochemical characterization, and structural studies of this novel mannanase are reported in this paper. The gene consists of 963 bp and encodes a 320-amino acid protein, AaManA. Based on its substrate specificity and product profile, AaManA is classified as an endo-beta-1,4-mannanase that is capable of transglycosylation. Kinetic analysis studies revealed that the enzyme required at least five subsites for efficient hydrolysis. The crystal structure at 1.9 angstroms resolution showed that AaManA adopted a (beta/alpha)8-barrel fold. Two catalytic residues were identified: Glu151 at the C terminus of beta-stand beta4 and Glu231 at the C terminus of beta7. Based on the structure of the enzyme and evidence of its transglycosylation activity, AaManA is placed in clan GH-A. Superpositioning of its structure with that of other clan GH-A enzymes revealed that six of the eight GH-A key residues were functionally conserved in AaManA, with the exceptions being residues Thr95 and Cys150. We propose a model of substrate binding in AaManA in which Glu282 interacts with the axial OH-C(2) in-2 subsites. Based on sequence comparisons, the enzyme was assigned to a new glycoside hydrolase family (GH113) that belongs to clan GH-A. 相似文献
972.
Our previous studies have indicated that TGF-beta1 exerts its effect on the expression of A-type potassium channels (I(A)) in rat vascular myofibroblasts by activation of protein kinase C during the phenotypic transformation of vascular fibroblasts to myofibroblasts. In the present study, patch-clamp whole-cell recording and transwell-migration assays were used to examine the effects of TGF-beta1- and phorbol 12-myristate 13-acetate (PMA)-induced expression of I(A) channels on myofibroblast migration and its modulation by the protein kinase A (PKA) pathway. Our results reveal that incubation of fibroblasts with TGF-beta1 or PMA up-regulates the expression of I(A) channels and increases myofibroblast migration. Blocking I(A) channel expression by 4-aminopyridine (4-AP) significantly inhibits TGF-beta1- and PMA-induced myofibroblast migration. Incubation of fibroblasts with forskolin does not result in increased expression of I(A) channels but does cause a slight increase in fibroblast migration at higher concentrations. In addition, forskolin increases the TGF-beta1- and PMA-induced myofibroblast migration but inhibits TGF-beta1- and PMA-induced the expression of I(A) channels. Whole-cell current recordings showed that forskolin augments the delayed rectifier outward K(+) (I(K)) current amplitude of fibroblasts, but not the I(A) of myofibroblasts. Our results also indicate that TGF-beta1- and PMA-induced expression of I(A) channels might be related to increase TGF-beta1- or PMA-induced myofibroblast migration. Promoting fibroblast and myofibroblast migration via the PKA pathway does not seem to involve the expression of I(A) channels, but the modulation of I(K) and I(A) channels might be implicated. 相似文献
973.
This study isolated nine strains of aerobic phenol-degrading granules. These isolates (I1–I9) were characterized using 16S
rRNA gene sequencing, with γ-Proteobacteria as the dominant strains in the aerobic granules. While most strains demonstrated either high phenol-degrading capabilities
or auto-aggregation capabilities, three isolates, I2, I6, and I8 showed both features. These findings contradict the previous
view that auto-aggregation and phenol degradation are mutually exclusive in aerobic granules. Strains I2 and I8 independently
formed single-culture aerobic granules except for I3. Anti-microbial activity test results indicated that strains I2 and I8
inhibited growth of strain I3. However, co-culturing I3 with I2 or I8 helped to form granules. 相似文献
974.
Proteomic analysis of cervical cancer cells treated with suberonylanilide hydroxamic acid 总被引:1,自引:0,他引:1
Jianxiong He Canhua Huang Aiping Tong Bin Chen Zhi Zeng Peng Zhang Chunting Wang Yuquan Wei 《Journal of biosciences》2008,33(5):715-721
Suberonylanilide hydroxamic acid (SAHA) is an orally administered histone deacetylase inhibitor (HDACI) that has shown significant
antitumour activity in a variety of tumour cells. To identify proteins involved in its antitumour activity, we utilized a
proteomic approach to reveal protein expression changes in the human cervical cancer cell line HeLa following SAHA treatment.
Protein expression profiles were analysed by 2-dimensional polyacrylamide gel electrophoresis (2-DE) and protein identification
was performed on a MALDI-Q-TOF MS/MS instrument. As a result, a total of nine differentially expressed proteins were visualized
by 2-DE and Coomassie brilliant blue (CBB) staining. Further, all the changed proteins were positively identified via mass
spectrometry (MS)/MS analysis. Of these, PGAM1 was significantly downregulated in HeLa cells after treatment with SAHA. Moreover,
PGAM1 has been proven to be downregulated in another cervical cancer cell line (CaSki) by western blot analysis. Together,
using proteomic tools, we identified several differentially expressed proteins that underwent SAHA-induced apoptosis. These
changed proteins may provide some clues to a better understanding of the molecular mechanisms underlying SAHA-induced apoptosis
in cervical cancer. 相似文献
975.
Pi Y Liao Z Jiang K Huang B Deng Z Zhao D Zeng H Sun X Tang K 《Bioscience reports》2008,28(6):349-355
AOC (allene oxide cyclase; EC 5.3.99.6), an essential enzyme in jasmonic acid and its methyl ester biosynthesis, was cloned from Camptotheca acuminata (named as CaAOC), a native medicinal plant species in China. CaAOC had significant similarity at the amino-acid level with AOCs from other plant species. Comparison between the sequences of the full-length cDNA and genomic DNA of CaAOC revealed that the genomic DNA of CaAOC contained an 89-bp intron and a 240-bp intron. Southern-blot analysis indicated that CaAOC was a multiple-copy gene, and real-time quantitative PCR analysis showed that CaAOC was expressed constitutively in all organs tested, with the highest expression level in leaves. The results from treatment experiments using different signalling components, including methyl jasmonate, abscisic acid, salicylic acid and H(2)O(2), revealed that expression of CaAOC had a prominent diversity. Heavy metal (copper) significantly enhanced CaAOC expression, whereas wounding (induced by UV-B) was not so effective. 相似文献
976.
Tang JN Zeng ZG Wang HN Yang T Zhang PJ Li YL Zhang AY Fan WQ Zhang Y Yang X Zhao SJ Tian GB Zou LK 《Journal of microbiological methods》2008,75(3):432-436
Polymerase chain reaction (PCR) detection of microorganism in faecal specimens is hampered by poor recovery of DNA and by the presence of PCR inhibitors. In this paper, we describe a new modified method for extracting PCR-quality microbial community DNA from pig faecal samples, which combines the pretreatment with polyformaldehyde, and subsequent DNA lysis in the presence of CTAB, salt, PVP, and beta-mercaptoethanol, followed by isolation of nucleic acids using chloroform (no phenol) based protocol. The method resulted in a 1.3- to 11-fold increase in DNA yield when compared to four other widely used methods. Genomic DNA extracted from all five methods was assessed by both agarose gel electrophoresis and polymerase chain reaction for amplification of 16S rDNA specific fragments. The results showed that the improved method represented a reproducible, simple, and rapid technique for routine DNA extraction from faecal specimens and was notably better than using the QIAamp DNA Stool Mini Kit. 相似文献
977.
Multiplex PCR and DNA microarray were combined with tyramide signal amplification (TSA) to develop a reliable method suitable for simultaneous detection of six species of human diarrheal pathogens (Yersinia enterocolitica, Shigella spp, Salmonella typhi, Brucella spp, Vibrio cholera and Escherichia coli O157:H7). Meanwhile, our method could distinguish V. cholera serotype O1 from O139, and O157:H7 from O157: non-H7. This assay conferred a specificity of 100% for target pathogens. The limit of detection was 103 degrees CFU/mL approximately. The results of 98.6% (357/362) clinical specimens and 100% (5/5) mocked double-blind samples were the same to that from conventional assay. Consequently this assay is sensitive and a specific tool suitable for diagnostic detection and surveillance of multiple human pathogens. 相似文献
978.
Zeng T Guo FF Zhang CL Zhao S Dou DD Gao XC Xie KQ 《Chemico-biological interactions》2008,176(2-3):234-242
The protective effects of single dose of garlic oil (GO) on acute ethanol-induced fatty liver were investigated. Mice were treated with ethanol (4.8 g/kg bw) to induce acute fatty liver. The liver index, the serum and hepatic triglyceride (TG) levels and the histological changes were examined to evaluate the protective effects. Hepatic malondialdehyde (MDA), glutathione (GSH) levels and superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GSH-Px), glutathione-S-transferase (GST) activities were determined for the antioxidant capacity assay. Acute ethanol exposure resulted in the enlargement of the liver index and the increase of the serum and hepatic TG levels (P<0.01), which were dramatically attenuated by GO pretreatment in a dose-dependent manner (P<0.01). GO treatment (simultaneously with ethanol exposure) exhibited similar effects to those of pretreatment, while no obviously protective effects were displayed when it was used at 2h after ethanol intake. Histological changes were paralleled to these indices. Beside this, GO dramatically prolonged the drunken time and shortened the waking time, and these effects were superior to those of silymarin and tea polyphenol. In addition, GO dose-dependently suppressed the elevation of MDA levels, restored the GSH levels and enhanced the SOD, GR and GST activities. Compared with the ethanol group, the MDA levels decreased by 14.2% (P<0.05), 29.9% and 32.8% (P<0.01) in GO groups 50, 100 and 200 mg/kg, respectively. The GST activity increased by 9.97%, 19.94% (P<0.05) and 42.12% (P<0.01) of the ethanol group in GO groups 50, 100 and 200 mg/kg, respectively, while the GR activity increased by 28.57% (P<0.05), 37.97% (P<0.01), 50.45% (P<0.01) of the ethanol group in GO groups 50, 100 and 200 mg/kg, respectively. These data indicated that single dose of GO possessed ability to prevent acute ethanol-induced fatty liver, but may lose its capacity when used after ethanol exposure. The protective effects should be associated with its antioxidative activities. 相似文献
979.
980.
Post-translational modification of the p53 family members is key to their regulation. Here we report the phosphorylation of TAp63gamma, but not DeltaNp63gamma, by IkappaB kinase beta (IKKbeta). Activation of IKKbeta by gamma radiation or tumor necrosis factor-alpha led to increased TAp63gamma protein levels in cells. IKKbeta, but not its kinase-defective mutant IKKbeta-K44A, led to this observed stabilization of TAp63gamma. This stabilization of TAp63gamma in response to gamma radiation was significantly decreased in the absence of IKKbeta. Phosphorylation of TAp63gamma blocks ubiquitylation and possible degradation of this protein. We postulate that phosphorylation of TAp63gamma by IKKbeta stabilizes the TAp63gamma protein by blocking ubiquitylation-dependent degradation of this protein. 相似文献