排序方式: 共有353条查询结果,搜索用时 265 毫秒
101.
Catalase was covalently immobilized onto florisil via glutaraldehyde (GA) and glutaraldehyde+6-amino hexanoic acid (6-AHA) (as a spacer arm). Immobilizations of catalase onto modified supports were optimized to improve the efficiency of the overall immobilization procedures. The V(max) values of catalase immobilized via glutaraldehyde (CIG) and catalase immobilized via glutaraldehyde+6-amino hexanoic acid (CIG-6-AHA) were about 0.6 and 3.4% of free catalase, respectively. The usage of 6-AHA as a spacer arm caused about 40 folds increase in catalytic efficiency of CIG-6-AHA (8.3 × 10? M?1 s?1) as compared to that of CIG (2.1 × 10? M?1 s?1). CIG and CIG-6-AHA retained 67 and 35% of their initial activities at 5 °C and 71 and 18% of their initial activities, respectively at room temperature at the end of 6 days. Operational stabilities of CIG and CIG-6-AHA were investigated in batch and plug-flow type reactors. The highest total amount of decomposed hydrogen peroxide (TAD-H?O?) was determined as 219.5 μmol for CIG-6-AHA in plug-flow type reactor. 相似文献
102.
Mbd3/NURD complex regulates expression of 5-hydroxymethylcytosine marked genes in embryonic stem cells 总被引:1,自引:0,他引:1
Numerous chromatin regulators are required for embryonic stem (ES) cell self-renewal and pluripotency, but few have been studied in detail. Here, we examine the roles of several chromatin regulators whose loss affects the pluripotent state of ES cells. We find that Mbd3 and Brg1 antagonistically regulate a common set of genes by regulating promoter nucleosome occupancy. Furthermore, both Mbd3 and Brg1 play key roles in the biology of 5-hydroxymethylcytosine (5hmC): Mbd3 colocalizes with Tet1 and 5hmC in vivo, Mbd3 knockdown preferentially affects expression of 5hmC-marked genes, Mbd3 localization is Tet1-dependent, and Mbd3 preferentially binds to 5hmC relative to 5-methylcytosine in vitro. Finally, both Mbd3 and Brg1 are themselves required for normal levels of 5hmC in vivo. Together, our results identify an effector for 5hmC, and reveal that control of gene expression by antagonistic chromatin regulators is a surprisingly common regulatory strategy in ES cells. 相似文献
103.
104.
Identification of a lysosomal peptide transport system induced during dendritic cell development 总被引:1,自引:0,他引:1
Demirel O Waibler Z Kalinke U Grünebach F Appel S Brossart P Hasilik A Tampé R Abele R 《The Journal of biological chemistry》2007,282(52):37836-37843
The delivery of protein fragments to major histocompatibility complex (MHC)-loading compartments of professional antigen-presenting cells is essential in the adaptive immune response against pathogens. Apart from the crucial role of the transporter associated with antigen processing (TAP) for peptide loading of MHC class I molecules in the endoplasmic reticulum, TAP-independent translocation pathways have been proposed but not identified so far. Based on its overlapping substrate specificity with TAP, we herein investigated the ABC transporter ABCB9, also named TAP-like (TAPL). Remarkably, TAPL expression is strongly induced during differentiation of monocytes to dendritic cells and to macrophages. TAPL does not, however, restore MHC class I surface expression in TAP-deficient cells, demonstrating that TAPL alone or in combination with single TAP subunits does not form a functional transport complex required for peptide loading of MHC I in the endoplasmic reticulum. In fact, by using quantitative immunofluorescence and subcellular fractionation, TAPL was detected in the lysosomal compartment co-localizing with the lysosome-associated membrane protein LAMP-2. By in vitro assays, we demonstrate a TAPL-specific translocation of peptides into isolated lysosomes, which strictly requires ATP hydrolysis. These results suggest a mechanism by which antigenic peptides have access to the lysosomal compartment in professional antigen-presenting cells. 相似文献
105.
106.
Ozlem? Aksoy Feruzan?Dane Filiz?Ekinci Sanal Tulin?Aktac 《Acta Physiologiae Plantarum》2007,29(2):115-120
In this study, seed germination percentages, effects on phases of mitosis and α-amylase enzyme activity of lentil seeds treated
with four different concentrations (0.25, 0.5, 1 and 1.5%) of Fusilade (Fluazifop-p-butyl) were determined. Median EC (effective concentration) values were calculated according to seed germination percentages
after treatment for 72 h. Germination percentages of primary lentil roots decreased with increasing Fusilade concentrations.
Cytological observations showed that the mitotic frequency in root meristematic cells were decreased parallel to the increase
in concentrations and all Fusilade concentrations applied decreased the activity of α-amylase enzyme in lentil seeds. The
obtained results indicate that the herbicide Fusilade had the ability to cause reduction in seed germination, mitotic frequency
and also α-amylase activity of lentil seeds. 相似文献
107.
1. Glial cells are the most abundant cell population in the central nervous system. The aim of this study was to examine the
effects of melatonin, 7-nitroindazole, and riluzole on glutamate toxicity in primary glial cell culture.
2. Glutamate toxicity was induced by addition of 100 μM glutamate to the cultures, and then 100 μM melatonin, 500 μM 7-nitroindazole,
and 10 (M riluzole were administered in different groups. Lactate Dehydrogenase activity and nitrite levels were determined
at the 1st, 6th, and 24th h.
3. Melatonin, 7-nitroindazole, and riluzole decrease Lactate Dehydrogenase activity at the 1st, 6th, and 24th h (at all hours,
p<0.05). Nitrite levels were decreased by melatonin and riluzole at the 1st, 6th, and 24th h.
4. In this study, we observed that melatonin, 7-nitroindazole, and riluzole are effective as protective agents on glutamate
toxicity in mixed glial cells. 相似文献
108.
Consequences of epididymal ligation on prepubertal rats 总被引:1,自引:0,他引:1
Aktug H Ozdedeli K Altay B Cüreklibatur I Turna B Yilmaz O 《Analytical and quantitative cytology and histology / the International Academy of Cytology [and] American Society of Cytology》2007,29(1):50-56
OBJECTIVE: To study prospectively experimental effects of unilateral epididymal obstruction on testis and epididymis histopathologically in prepubertal rats. STUDY DESIGN: Organ weights, mean seminiferous tubule diameter (MSTD), mean ductus epididymis diameter (MDED), mean tubular biopsy scores (MTBS) and histopathology of 21 male albino Wistar rats were compared with the immunostaining affinity of anti-desmin, anti-vimentin, anti-laminin and anti-collagen antibodies. RESULTS: Statistical analysis of mean weight of testes, MTBS, mean epididymal weight, MDED and MSTD was significant. Evaluation of testis and epididymis revealed cellular damage, basal membrane impairment and granulomatous infiltration. CONCLUSION: Histopathologic alterations with MSTD are early indicators for ipsilateral and contralateral injury. Even the presence of criteria such as intactness and cellular integrity does not guarantee there is no sperm leakage or immunologic damage. Therefore the impairment of basal integrity is a switch code in determining spermatogenic failure. 相似文献
109.
Ertan T Yildiz I Ozkan S Temiz-Arpaci O Kaynak F Yalcin I Aki-Sener E Abbasoglu U 《Bioorganic & medicinal chemistry》2007,15(5):2032-2044
A new series of N-(2-hydroxy-4(or 5)-nitro/aminophenyl)benzamide and phenylacetamide derivatives (1a-1n, 2a-2n) were synthesized and evaluated for antibacterial and antifungal activities against Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, and their drug-resistant isolate. Microbiological results indicated that the compounds possessed a broad spectrum of activity against the tested microorganisms at MIC values between 500 and 1.95 microg/ml. Benzamide derivative 1d exhibited the greatest activity with MIC values of 1.95, 3.9, and 7.8 microg/ml against drug-resistant B. subtilis, B. subtilis, and S. aureus, respectively. 相似文献
110.
We studied a data set of structurally similar interfaces that bind to proteins with different binding-site structures and different functions. Our multipartner protein interface clusters enable us to address questions like: What makes a given site bind different proteins? How similar/different are the interactions? And, what drives the apparently less-specific association? We find that proteins with common binding-site motifs preferentially use conserved interactions at similar interface locations, despite the different partners. Helices are major vehicles for binding different partners, allowing alternate ways to achieve favorable association. The binding sites are characterized by imperfect packing, planar architectures, bridging water molecules, and, on average, smaller size. Interestingly, analysis of the connectivity of these proteins illustrates that they have more interactions with other proteins. These findings are important in predicting "date hubs," if we assume that "date hubs" are shared proteins with binding sites capable of transient binding to multipartners, linking higher-order networks. 相似文献