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排序方式: 共有173条查询结果,搜索用时 46 毫秒
1.
Lorne J. Brandes Mark W. Hermonat 《Biochemical and biophysical research communications》1984,123(2):724-728
A new para-diphenylmethyl derivative, N,N-diethyl-2-[(4-phenylmethyl)-phenoxy]-ethanamine·HCl (N,N-DPPE) has been synthesized which binds with high affinity to the anti-estrogen binding site found in male rat liver microsomes. However, no evidence of significant interaction with the estrogen receptor can be observed at or below 10 μM in rat uterine cytosols; 10 nM N,N-DPPE fails to significantly induce progesterone receptor in MCF-7 cells. Tamoxifen also binds to anti-estrogen binding site but, unlike N,N-DPPE, binds significantly to estrogen receptor at much loeer concentrations and induces MCF-7 progesterone receptor. This property of high affinity for anti-estrogen binding site but not for estrogen receptor may make N,N-DPPE an important probe for the study of anti-estrogen binding site and its biological relevance. 相似文献
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Wen-Zong Whong 《Mutation research》1979,60(3):301-312
The nature of the N2 effect for ICR-170, i.e., the greater mutagenic and lethal activities of this agent in the presence of N2 than O2, has been studied at the ad-3 region of Neurospora crassa. The characteristics of the N2 effect for ICR-170 were that (1) the N2 effect with ICR-170 was displayed in conidia when N2 was administered during, but not before or after, ICR-170 treatment, (2) the highly increased mutagenic and lethal activities of ICR-170 in the presence of N2 were due to an anoxic condition rather than to the presence of N2 per se, (3) the high killing activity of ICR-170 under N2 was due largely to increased cytoplasmic inactivation, (4) the N2 effect was a general phenomenon at the ad-3 region of N. crassa, and (5) the highly ICR-170-induced mutation in conidia under N2 was attributable to an actual enhancement in the mutagenic activity of ICR-170 rather than to selective killing. With regard to the mechanisms of the N2 effect with ICR-170, results indicate that this effect (1) was not due to more extracellular oxidative degradation of ICR-170 molecules in the presence of O2, or to a greater uptake of ICR-170 by conidia under N2, but (2) was due to the inhibition of conidial respiration under an anoxic environment. 相似文献
4.
The synthesis of benzylpenicillin (BP) after mixing phenyl-acetyl-glycine(PAG), 6-aminopenicillanic acid (6-APA) and free or immobilized penicillin amidase (E.C.3.5.1.11.) was studied as a function of pH and ionic strength. Before the final equilibrium was reached a kinetically controlled synthesis of BP was observed. Then a transient maximum concentration in BP much larger than the final equilibrium content was synthesized in the acyl-transfer process. The factors influencing this maximum have been analyzed. Increasing ionic strength markedly decreased the maximum in BP and the rate of deacylation of phenyl-acetyl-penicillin amidase by 6-APA. The change was largest when the enzyme was immobilized in a positively charged support, where at low ionic strength the concentration of 6-APA around the enzyme is larger than the bulk concentration due to the partitioning of charged solutes. 相似文献
5.
Variation between mouse major urinary protein genes isolated from a single inbred line 总被引:13,自引:0,他引:13
We describe ten Charon 4A genomic DNA clones from BALB/c mice which include at least seven different major urinary protein (MUP) genes. We have established the orientation of all seven sequences, and have placed six of them in precise register by means of restriction site maps and Southern blot hybridization with cloned cDNA sequences. Four of the seven genomic sequences (family I sequences) form hybrids with six independent cDNA clones that have a high thermal stability and hybridize more strongly with mRNA from three inbred mouse lines. Hybrids between the remaining three genomic sequences and the cDNA clones have a lower thermal stability and hybridize less strongly with mRNA from the three inbred lines. Homologies between different cloned sequences extend over as much as 15 kb. No clone contains parts of two MUP genes, and no homology has been detected between the 3' flanking region of one MUP gene and the 5' flanking region of another. 相似文献
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Jolanta Krudysz-Amblo Mark E. Jennings II Tyler Knight Dwight E. Matthews Kenneth G. Mann Saulius Butenas 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Tissue factor (TF), an in vivo initiator of blood coagulation, is a transmembrane protein and has two disulfides in the extracellular domain. The integrity of one cysteine pair, Cys186–Cys209, has been hypothesized to be essential for an allosteric “decryption” phenomenon, presumably regulating TF procoagulant function, which has been the subject of a lengthy debate. The conclusions of published studies on this subject are based on indirect evidences obtained by the use of reagents with potentially oxidizing/reducing properties.Methods
The status of disulfides in recombinant TF1–263 and natural placental TF in their non-reduced native and reduced forms was determined by mass-spectrometry. Functional assays were performed to assess TF cofactor function.Results
In native proteins, all four cysteines of the extracellular domain of TF are oxidized. Reduced TF retains factor VIIa binding capacity but completely loses the cofactor function.Conclusion
The reduction of TF disulfides (with or without alkylation) eliminates TF regulation of factor VIIa catalytic function in both membrane dependent FX activation and membrane independent synthetic substrate hydrolysis.General significance
Results of this study advance our knowledge on TF structure/function relationships. 相似文献9.
Annett Sandner Juliane Illert Sabine Koitzsch Susanne Unverzagt Ilona Schön 《Experimental cell research》2013
Gastroesophageal reflux disease has been implicated in the pathogenesis of adenocarcinoma of the oesophagus. The same applies to laryngopharyngeal reflux (LPR) and squamous cell cancer of the head and neck, but so far, this link has not been proven. The impact of low pH and bile acids has not been studied extensively in cells other than oesophageal cancer cell lines and tissue. The aims of this study were to investigate the pathogenic potential of reflux and its single components on the mucosa of the upper respiratory tract. We measured DNA stability in human miniorgan cultures (MOCs) and primary epithelial cell cultures (EpCs) in response to reflux by the alkaline comet assay. As matrix metalloproteinases (MMPs) are involved in extracellular matrix remodelling processes and may contribute to cancer progression, we studied the expression of MMP1, -9, and -14 in MOCs, EpC, UM-SCC-22B, and FADUDD. DNA strand breaks (DNA-SBs) increased significantly at low pH and after incubation with human or artificial gastric juice. Single incubation with glycochenodeoxycholic acid also showed a significant increase in DNA-SBs. In epithelial cell cultures, human gastric juice increased the number of DNA-SBs at pH 4.5 and 5.5. Artificial gastric juice significantly up regulated the gene expression of MMP9. Western blot analysis confirmed the results of gene expression analysis, but the up regulation of MMP1, -9, and -14 was donor-specific. Reflux has the ability to promote genomic instability and may contribute to micro environmental changes suitable for the initiation of malignancy. Further functional gene analysis may elucidate the role of laryngopharyngeal reflux in the development of head neck squamous cell carcinoma (HNSCC). 相似文献
10.
Srikantamurthy Ningaiah Umesha K. Bhadraiah Shubakara Keshavamurthy Chethan Javarasetty 《Bioorganic & medicinal chemistry letters》2013,23(16):4532-4539
A novel series of pyrazoline amidoxime (2a–d) and pyrazoly-1,2,4-oxadiazole (3a–p) and (4) of pharmacological significance have been synthesised. Structures of newly synthesised compounds were characterized by spectral studies. New compounds were screened for their in vitro antioxidant, antimicrobial and antiinflammatory activities. Among the synthesized compounds, compound 2a, 3l and 3o were found to be active antimicrobial agents in addition to having potent antioxidant activity, while the compound 3f showed promising antiinflammatory activity in comparison with standard drug. 相似文献