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排序方式: 共有395条查询结果,搜索用时 15 毫秒
21.
Belicová Anna Krajčovič Juraj Križková Lìvia Ebringer Libor Košíková Božena 《World journal of microbiology & biotechnology》2000,16(1):91-93
Sulphur-free lignin biopolymer and its oxidized and reduced derivatives have been prepared and their inhibitory activity against u.v.-induced mutagenesis in Euglena gracilis was evaluated. The structure- and dose-dependent anti-u.v. activity of lignins was observed at concentrations higher than 250gml–1. The oxidized lignin showed the most antimutagenic activity, followed by the reduced lignin and the unmodified lignin had the least antimutagenic activity. 相似文献
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23.
Laszlo Revesz Achim Schlapbach Reiner Aichholz Janet Dawson Roland Feifel Stuart Hawtin Amanda Littlewood-Evans Guido Koch Markus Kroemer Henrik Möbitz Clemens Scheufler Juraj Velcicky Christine Huppertz 《Bioorganic & medicinal chemistry letters》2010,20(15):4719-4723
Spirocyclopropane- and spiroazetidine-substituted tetracycles 13D–E and 16A are described as orally active MK2 inhibitors. The spiroazetidine derivatives are potent MK2 inhibitors with IC50 <3 nM and inhibit the release of TNFα (IC50<0.3 μM) from hPBMCs and hsp27 phosphorylation in anisomycin stimulated THP-1 cells. The spirocyclopropane analogues are less potent against MK2 (IC50 = 0.05–0.23 μM), less potent in cells (IC50 <1.1 μM), but show good oral absorption. Compound 13E (100 mg/kg po; bid) showed oral activity in rAIA and mCIA, with significant reduction of swelling and histological score. 相似文献
24.
Glucoamylase is an extracellular enzyme produced mainly by microorganisms. It belongs to the commercially frequently exploited
biocatalysts. The major application of glucoamylase is in the starch bioprocessing to produce glucose and in alcoholic fermentations
of starchy materials. Filamentous fungi have been the source of glucoamylases for industrial purposes as well as an object
of numerous research studies. Some yeasts also secrete a large amount of glucoamylase with biochemical characteristics slightly
different from those of filamentous fungi. Modern biotechnological applications require glucoamylases of certain properties
optimal for a given process. Novel biocatalysts can be prepared from already existing enzymes using techniques of protein
engineering or directed evolution. Tailoring of a commercial glucoamylase requires knowledge, on a molecular level, of structure/function
relationships of enzymes originating from various sources and having different catalytic properties. Sequences of the cloned
genes, their recombinant expression and the tertiary structure determination of glucoamylase are prerequisite to obtain such
information. The presented review focuses on molecular-genetic and structural aspects of yeast glucoamylases, supplemented
with the basic biochemical characterization of the given enzymes. 相似文献
25.
26.
Knezović J Kovac M Klapan I Mlinarić H Vranjes Z Lukinović J Rakić M 《Collegium antropologicum》2007,31(4):1143-1150
Conduction of tele-3D-computer assisted operations as well as other telemedicine procedures often requires highest possible quality of transmitted medical images and video. Unfortunately, those data types are always associated with high telecommunication and storage costs that sometimes prevent more frequent usage of such procedures. We present a novel algorithm for lossless compression of medical images that is extremely helpful in reducing the telecommunication and storage costs. The algorithm models the image properties around the current, unknown pixel and adjusts itself to the local image region. The main contribution of this work is the enhancement of the well known approach of predictor blends through highly adaptive determination of blending context on a pixel-by-pixel basis using classification technique. We show that this approach is well suited for medical image data compression. Results obtained with the proposed compression method on medical images are very encouraging, beating several well known lossless compression methods. The predictor proposed can also be used in other image processing applications such as segmentation and extraction of image regions. 相似文献
27.
Lenco J Hubálek M Larsson P Fucíková A Brychta M Macela A Stulík J 《FEMS microbiology letters》2007,269(1):11-21
Francisella tularensis is a highly virulent, facultative intracellular pathogen that causes tularemia in humans and animals. Although it is one of the most infectious bacterial pathogens, little is known about its virulence mechanisms. In this study, the response of F. tularensis live vaccine strain to iron depletion, which simulates the environment within the host, was investigated. In order to detect alterations in protein synthesis, metabolic labeling, followed by 2D-PAGE analysis was used. Globally, 141 protein spots were detected whose levels were significantly altered in the iron-restricted medium. About 65% of the spots were successfully identified using mass spectrometric approaches. Importantly, among the proteins produced at an increased level during iron-limited growth, three proteins were found encoded by the igl operon, located in the F. tularensis pathogenicity island I (FPI). Of these, the IglC and IglA proteins were previously reported to be necessary for full virulence of F. tularensis. These results, obtained at the proteome level, support and confirm recently published data showing that the igl operon genes are transcribed in response to iron limitation. 相似文献
28.
Yoshikawa D Kopacek J Yamaguchi N Ishibashi D Yamanaka H Yamaguchi Y Katamine S Sakaguchi S 《Gene》2007,386(1-2):139-146
We and others previously showed that, in some lines of prion protein (PrP)-knockout mice, the downstream PrP-like protein (PrPLP/Dpl) was abnormally expressed in brains partly due to impaired cleavage/polyadenylation of the residual PrP promoter-driven pre-mRNA despite the presence of a poly(A) signal. In this study, we newly established an in vitro transient transfection system in which abnormal expression of PrPLP/Dpl can be visualized by expression of the green fluorescence protein, EGFP, in cultured cells. No EGFP was detected in cells transfected by a vector carrying a PrP genomic fragment including the region targeted in the knockout mice intact upstream of the PrPLP/Dpl gene. In contrast, deletion of the targeted region from the vector caused expression of EGFP. By employing this system with other vectors carrying various deletions or point mutations in the targeted region, we identified that disruption of the splicing elements in the PrP terminal intron caused the expression of EGFP. Recent lines of evidence indicate that terminal intron splicing and cleavage/polyadenylation of pre-mRNA are functionally linked to each other. Taken together, our newly established system shows that the abnormal expression of PrPLP/Dpl in PrP-knockout mice caused by the impaired cleavage/polyadenylation of the PrP promoter-driven pre-mRNA is due to the functional dissociation between the pre-mRNA machineries, in particular those of cleavage/polyadenylation and splicing. Our newly established in vitro system, in which the functional dissociation between the pre-mRNA machineries can be visualized by EGFP green fluorescence, may be useful for studies of the functional connection of pre-mRNA machineries. 相似文献
29.
Jason?M.D. Kalapothakis Ryan?J. Morris Juraj Szavits-Nossan Kym Eden Sam Covill Sean Tabor Jay Gillam Perdita?E. Barran Rosalind?J. Allen Cait?E. MacPhee 《Biophysical journal》2015,108(9):2300-2311
The ability to control the morphologies of biomolecular aggregates is a central objective in the study of self-assembly processes. The development of predictive models offers the surest route for gaining such control. Under the right conditions, proteins will self-assemble into fibers that may rearrange themselves even further to form diverse structures, including the formation of closed loops. In this study, chicken egg white ovalbumin is used as a model for the study of fibril loops. By monitoring the kinetics of self-assembly, we demonstrate that loop formation is a consequence of end-to-end association between protein fibrils. A model of fibril formation kinetics, including end-joining, is developed and solved, showing that end-joining has a distinct effect on the growth of fibrillar mass density (which can be measured experimentally), establishing a link between self-assembly kinetics and the underlying growth mechanism. These results will enable experimentalists to infer fibrillar morphologies from an appropriate analysis of self-assembly kinetic data. 相似文献
30.
Accurate chromosome segregation depends on the proper attachment of sister kinetochores to microtubules emanating from opposite spindle poles. Merotelic kinetochore orientation is an error in which a single kinetochore is attached to microtubules emanating from both spindle poles. Despite correction mechanisms, merotelically attached kinetochores can persist until anaphase, causing chromatids to lag on the mitotic spindle and hindering their timely segregation. Recent studies showing that merotelic kinetochore attachment represents a major mechanism of aneuploidy in mitotic cells and is the primary mechanism of chromosomal instability in cancer cells have underlined the importance of studying merotely. Here, we highlight recent progress in our understanding of how cells prevent and correct merotelic kinetochore attachments. 相似文献