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排序方式: 共有193条查询结果,搜索用时 351 毫秒
1.
G Gradwohl A Mazen G de Murcia 《Biochemical and biophysical research communications》1987,148(3):913-919
The interaction between highly purified poly(ADP-ribose) polymerase from calf thymus and different topological forms of pBR322 DNA has been studied by gel retardation electrophoresis and electron microscopy. We show that: (i) in the absence of nicks on DNA the enzyme has a marked affinity for supercoiled (form I) DNA, (ii) in the presence of single stranded breaks poly(ADP-ribose) polymerase preferentially binds to form II, (iii) in all cases enzyme molecules are frequently located at DNA intersections, (iv) a cooperative binding of the enzyme on DNA occurs. 相似文献
2.
A Mazen J Menissier-de Murcia M Molinete F Simonin G Gradwohl G Poirier G de Murcia 《Nucleic acids research》1989,17(12):4689-4698
By Energy Dispersive X-ray fluorescence we have determined that calf thymus poly(ADP-ribose) polymerase binds two zinc ions per enzyme molecule. Using 65Zn (II) for detection of zinc binding proteins and polypeptides on western blots, we found that the zinc binding sites are localized in a 29 kd N-terminal fragment which is included in the DNA binding domain. Metal depletion and restoration experiments proved that zinc is essential for the binding of this fragment to DNA as tested by Southwestern assay. These results correlate with the existence of two putative zinc finger motifs present in the N-terminal part of the human enzyme. Poly(ADP-ribose)polymerase fingers could be involved in the recognition of DNA strand breaks and therefore in enzyme activation. 相似文献
3.
Thirty-nine species and 16 fungal genera were isolated from Egyptian cotton seeds, cotton seed meal and cotton seed cake on 1% glucose-Czapek's agar medium incubated at 28 °C. Aspergillus was the most frequent genus and it emerged in 87–100% of the samples contributing 70–98% of total fungi in the three substrates tested. The most common species were A. niger, A. flavus, A. fumigatus, A. terreus and Rhizopus stolonifer; A. niger, A. fumigatus and Penicillium corylophilum; and A. niger, A. flavus, A. terreus, A. nidulans and Rhizopus stolonifer, respectively. Cotton seeds and cotton seed products were naturally contaminated by aflatoxin B1 and B2. About 16% of the different substrates tested were positive for aflatoxin contamination. No citrinin, ochratoxin A, patulin, sterigmatocystin, diacetoxyscirpenol, T-2 toxin or zearalenone were detected in the samples assayed. 相似文献
4.
Two novel protein-tyrosine kinases, each with a second phosphotransferase-related catalytic domain, define a new class of protein kinase. 总被引:37,自引:12,他引:25
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A F Wilks A G Harpur R R Kurban S J Ralph G Zürcher A Ziemiecki 《Molecular and cellular biology》1991,11(4):2057-2065
The protein-tyrosine kinases (PTKs) are a burgeoning family of proteins, each of which bears a conserved domain of 250 to 300 amino acids capable of phosphorylating substrate proteins on tyrosine residues. We recently exploited the existence of two highly conserved sequence elements within the catalytic domain to generate PTK-specific degenerate oligonucleotide primers (A. F. Wilks, Proc. Natl. Acad. Sci. USA 86:1603-1607, 1989). By application of the polymerase chain reaction, portions of the catalytic domains of several novel PTKs were amplified. We describe here the primary sequence of one of these new PTKs, JAK1 (from Janus kinase), a member of a new class of PTK characterized by the presence of a second phosphotransferase-related domain immediately N terminal to the PTK domain. The second phosphotransferase domain bears all the hallmarks of a protein kinase, although its structure differs significantly from that of the PTK and threonine/serine kinase family members. A second member of this family (JAK2) has been partially characterized and exhibits a similar array of kinase-related domains. JAK1 is a large, widely expressed membrane-associated phosphoprotein of approximately 130,000 Da. The PTK activity of JAK1 has been located in the C-terminal PTK-like domain. The role of the second kinaselike domain is unknown. 相似文献
5.
Use of histone antibodies for studying chromatin topography and the phosphorylation of chromatin subunits 总被引:2,自引:0,他引:2
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Polyclonal and monoclonal antibodies specific for histones as well as sera directed against synthetic peptides of histones were used to probe the topography of chromatin subunits. In native chromatin, the regions corresponding to residues 130-135 of H3 and 6-18 of H2B were found to be exposed and able to interact with antibodies whereas the regions 26-35 and 36-43 of H2B and 80-89 and 85-102 of H4 were not. In vitro phosphorylation of H3 and H5 in native chromatin or of H3 in H1/H5-depleted chromatin led to a marked drop in the binding of antibodies specific for residues 130-135 of H3 and 6-18 of H2B. Phosphorylation of H1/H5-depleted chromatin also altered the degree of exposure of certain H2A epitopes but it did not affect the surface accessibility of residues 1-11 of H2B. 相似文献
6.
Mazen Amatoury Vera Merheb Jessica Langer Xin Maggie Wang Russell Clive Dale Fabienne Brilot 《Journal of visualized experiments : JoVE》2013,(81)
Over the recent years, antibodies against surface and conformational proteins involved in neurotransmission have been detected in autoimmune CNS diseases in children and adults. These antibodies have been used to guide diagnosis and treatment. Cell-based assays have improved the detection of antibodies in patient serum. They are based on the surface expression of brain antigens on eukaryotic cells, which are then incubated with diluted patient sera followed by fluorochrome-conjugated secondary antibodies. After washing, secondary antibody binding is then analyzed by flow cytometry. Our group has developed a high-throughput flow cytometry live cell-based assay to reliably detect antibodies against specific neurotransmitter receptors. This flow cytometry method is straight forward, quantitative, efficient, and the use of a high-throughput sampler system allows for large patient cohorts to be easily assayed in a short space of time. Additionally, this cell-based assay can be easily adapted to detect antibodies to many different antigenic targets, both from the central nervous system and periphery. Discovering additional novel antibody biomarkers will enable prompt and accurate diagnosis and improve treatment of immune-mediated disorders. 相似文献
7.
8.
This study was to report and describe the formation of Ca oxalate crystals and to explore whether there is any correlation between their abundant formation and the ability of plant to uptake and accumulate high levels of toxic metals. Soil-grown Corchorus olitorius L. (Tiliaceae) seedlings were further grown in water culture in the presence of Cd, Pb, Cu, or Al (0–10 g/ml) for 20 days. Light and electron microscopic examinations revealed a large number of intracellular prismatic-shaped Ca oxalate crystals in both leaf and callus cells. Crystals were formed in the vacuole, a single large crystal being formed per cell. The crystal-containing cells differed in size and shape from crystal-free cells, they were rich in organelles, membranes, and vesicles and have dense cytoplasm, enlarged nucleus and modified starch-lacking plastids with few grana. These cells look highly active. Corchorus plants treated with Cd, Pb, Cu, and Al accumulated these metals to the levels several times higher than untreated plants. The contents of Pb, Cd, Al, and Cu in leaf tissues of plants grown in the presence of 5 g/ml of these metals were 10, 20, 25, and 40 times higher, respectively, than those in plants grown on media devoid of them. X-ray microanalysis of Ca oxalate crystals in leaves from plants exposed to 5 g/ml Cd, Pb, Al, or Cu indicated the incorporation only of Al into these crystals. Results of this paper suggest a possible contribution for Ca oxalate-crystal formation in sequestering and tolerance of at least some toxic metals. 相似文献
9.
A human novel gene DERPC on 16q22.1 inhibits prostate tumor cell growth and its expression is decreased in prostate and renal tumors 总被引:2,自引:0,他引:2
Sun M Ma L Xu L Li J Zhang W Petrovics G Makarem M Sesterhenn I Zhang M Blanchette-Mackie EJ Moul J Srivastava S Zou Z 《Molecular medicine (Cambridge, Mass.)》2002,8(10):655-663
BACKGROUND: Deletion of chromosome 16q is frequently associated with diverse tumors. Numerous studies strongly suggest the presence of one or more tumor suppressor genes on chromosome 16q22 to 16qter including the widely studied cadherin gene family. However, the specific tumor suppressor genes residing in this region need better definition and characterization. MATERIAL AND METHODS: Standard molecular biology approaches have been used to clone and characterize the DERPC cDNA and its protein product on chromosome 16q22.1. Northern blotting was used to define the expression pattern in a multiple human tissue blots. DERPC expression was examined in multi-tumor array (Clontech, CA, USA) dot blot as well as in laser capture microdissection (LCM) derived prostate cancer (CaP) specimens by quantitative RT-PCR. Western blot analysis and a fluorescent microscopy were used to characterize the molecular size and the cellular location of green fluorescent protein (GFP)-tagged DERPC fusion proteins. A colony formation assay was conducted to determine the effects of DERPC expression on tumor cell growth. RESULTS: A novel gene DERPC (Decreased Expression in Renal and Prostate Cancer) was identified and characterized. DERPC encoded a strong basic, proline- and glycine-rich nuclear protein. DERPC was ubiquitously expressed, with abundant expression in kidney, skeletal muscle, testis, liver, ovary, and heart and moderate expression in prostate. DERPC expression was reduced in renal (67%) and prostate tumors (33%). Expression of DERPC has inhibitory potential on CaP cell growth. Further, overexpression of DERPC in LNCaP cells caused alterations of nuclear morphology. CONCLUSION: This study suggests that decreased expression of DERPC may be implicated in tumorigenesis of renal and CaPs. 相似文献
10.
A sensitive, rapid and inexpensive analysis method has been developed for the triazines most frequently used in Palestine; the method includes fluorodensitometric screening and densitometric determination of the individual substances. Terbutryn as a model substance was derivatized with dansyl chloride in sodium hydrogen-carbonate or phosphate buffer solution to yield a green-blue fluorescent compound. Derivatization occurred at 120 degrees C within maximum of 10-min reaction time. The fluorescent compound formed was separated from excess reagent and other by-products on silica gel TLC plates and was then determined fluorodensitometrically. A linearity range between 20 and 1200 pg/spot was achieved. The method was also applied to other triazine herbicides such as ametryn, atrazine, propazine, terbuthylazine and simazine. Drinking water samples spiked with triazines were extracted using RP-C18 polar plus cartridges, and the extract could be then dansylated as a total. Recoveries were between 88% and 95%; the detection limit was 10 pg/spot and could be further improved to 2 pg/spot by a dipping solution. For quantification, each of the six triazines can be separated on one of three different stationary phases after solid phase extraction and measured densitometrically. The LOD for each individual triazine was 100 ng/l. 相似文献