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排序方式: 共有523条查询结果,搜索用时 15 毫秒
71.
Martina Pressová Miloš Buděšínský Ivana Košiová Vladimír Kopecký Jr. Josef Cvačka Václav Kašička Ondřej Šimák Zdeněk Točík Ivan Rosenberg 《Biopolymers》2010,93(3):277-289
In an attempt to prepare a library of short oligoadenylate analogues featuring both the enzyme‐stable internucleotide linkage and the 5′‐O‐methylphosphonate moiety and thus obtain a pool of potential RNase L agonists/antagonists, we studied the spontaneous polycondensation of the adenosin‐5′‐O‐ylmethylphosphonic acid (pcA), an isopolar AMP analogue, and its imidazolide derivatives employing N,N′‐dicyclohexylcarbodiimide under nonaqueous conditions and uranyl ions under aqueous conditions, respectively. The RP LC–MS analyses of the reaction mixtures per se, and those obtained after the periodate treatment, along with analyses and separations by capillary zone electrophoresis, allowed us to characterize major linear and cyclic oligoadenylates obtained. The structure of selected compounds was supported, after their isolation, by NMR spectroscopy. Ab initio calculation of the model structures simulating the AMP‐imidazolide and pcA‐imidazolide offered the explanation why the latter compound exerted, in contrast to AMP‐imidazolide, a very low stability in aqueous solutions. © 2009 Wiley Periodicals, Inc. Biopolymers 93: 277–289, 2010. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com 相似文献
72.
Hill S Lamberson CR Xu L To R Tsui HS Shmanai VV Bekish AV Awad AM Marbois BN Cantor CR Porter NA Clarke CF Shchepinov MS 《Free radical biology & medicine》2012,53(4):893-906
Polyunsaturated fatty acids (PUFAs) undergo autoxidation and generate reactive carbonyl compounds that are toxic to cells and associated with apoptotic cell death, age-related neurodegenerative diseases, and atherosclerosis. PUFA autoxidation is initiated by the abstraction of bis-allylic hydrogen atoms. Replacement of the bis-allylic hydrogen atoms with deuterium atoms (termed site-specific isotope-reinforcement) arrests PUFA autoxidation due to the isotope effect. Kinetic competition experiments show that the kinetic isotope effect for the propagation rate constant of Lin autoxidation compared to that of 11,11-D(2)-Lin is 12.8 ± 0.6. We investigate the effects of different isotope-reinforced PUFAs and natural PUFAs on the viability of coenzyme Q-deficient Saccharomyces cerevisiae coq mutants and wild-type yeast subjected to copper stress. Cells treated with a C11-BODIPY fluorescent probe to monitor lipid oxidation products show that lipid peroxidation precedes the loss of viability due to H-PUFA toxicity. We show that replacement of just one bis-allylic hydrogen atom with deuterium is sufficient to arrest lipid autoxidation. In contrast, PUFAs reinforced with two deuterium atoms at mono-allylic sites remain susceptible to autoxidation. Surprisingly, yeast treated with a mixture of approximately 20%:80% isotope-reinforced D-PUFA:natural H-PUFA are protected from lipid autoxidation-mediated cell killing. The findings reported here show that inclusion of only a small fraction of PUFAs deuterated at the bis-allylic sites is sufficient to profoundly inhibit the chain reaction of nondeuterated PUFAs in yeast. 相似文献
73.
Q. Meng C. Garcia-Rodriguez G. Manzanarez M.A. Silberg F. Conrad J. Bettencourt X. Pan T. Breece R. To M. Li D. Lee L. Thorner M.T. Tomic J.D. Marks 《Analytical biochemistry》2012,430(2):141-150
Quantitation of individual monoclonal antibodies (mAbs) within a combined antibody drug product is required for preclinical and clinical drug development. We have developed two antitoxins, XOMA 3B and XOMA 3E, each consisting of three mAbs that neutralize type B and type E botulinum neurotoxin (BoNT/B and BoNT/E) to treat serotype B and E botulism. To develop mAb-specific binding assays for each antitoxin, we mapped the epitopes of the six mAbs. Each mAb bound an epitope on either the BoNT light chain (LC) or translocation domain (HN). Epitope mapping data were used to design LC-HN domains with orthogonal mutations to make them specific for only one mAb in either XOMA 3B or XOMA 3E. Mutant LC-HN domains were cloned, expressed, and purified from Escherichia coli. Each mAb bound only to its specific domain with affinity comparable to the binding to holotoxin. Further engineering of domains allowed construction of enzyme-linked immunosorbent assays (ELISAs) that could characterize the integrity, binding affinity, and identity of each of the six mAbs in XOMA 3B and 3E without interference from the three BoNT/A mAbs in XOMA 3AB. Such antigen engineering is a general method allowing quantitation and characterization of individual mAbs in a mAb cocktail that bind the same protein. 相似文献
74.
For a given set L of species and a set T of triplets on L, we seek to construct a phylogenetic network which is consistent with T i.e. which represents all triplets of T. The level of a network is defined as the maximum number of hybrid vertices in its biconnected components. When T is dense, there exist polynomial time algorithms to construct level-0,1 and 2 networks (Aho et al., 1981; Jansson, Nguyen and Sung, 2006; Jansson and Sung, 2006; Iersel et al., 2009). For higher levels, partial answers were obtained in the paper by Iersel and Kelk (2008), with a polynomial time algorithm for simple networks. In this paper, we detail the first complete answer for the general case, solving a problem proposed in Jansson and Sung (2006) and Iersel et al. (2009). For any k fixed, it is possible to construct a level-k network having the minimum number of hybrid vertices and consistent with T, if there is any, in time O(T(k+1)n([4k/3]+1)). 相似文献
75.
SQ To K Takagi Y Miki K Suzuki E Abe Y Yang H Sasano ER Simpson KC Knower CD Clyne 《The Journal of steroid biochemistry and molecular biology》2012,132(3-5):331-338
The increase in local oestrogen production seen in oestrogen receptor positive (ER+) breast cancers is driven by increased activity of the aromatase enzyme. CYP19A1, the encoding gene for aromatase, is often overexpressed in the oestrogen-producing cells of the breast adipose fibroblasts (BAFs) surrounding an ER+ tumour, and the molecular processes underlying this upregulation is important in the development of breast-specific aromatase inhibitors for breast cancer therapy. Prostaglandin E2 (PGE2), a factor secreted by tumours, is known to stimulate CYP19A1 expression in human BAFs. The hormonal regulation of this process has been examined; however, what is less well understood is the emerging role of epigenetic mechanisms and how they modulate PGE2 signalling. This present study characterises the epigenetic processes underlying expression of the prostanoid receptor EP2 in the context of ER+ breast cancer. Sodium bisulphite sequencing of CpG methylation within the promoter region of EP2 revealed that an inverse correlation existed between methylation levels and relative EP2 expression in breast cancer cell lines MDA-MB-231, MCF7 and MCF10A but not in HS578t and T47D. Inhibition of DNA methylation with 5-aza-2'-deoxycytidine (5aza) and histone deacetylation with Trichostatin A (TSA) resulted in upregulation of EP2 mRNA in all cell lines with varying influences of each epigenetic process observed. Expression of EP2 was detected in human BAFs despite a natively methylated promoter, and this expression was further increased upon 5aza treatment. An examination of 3 triple negative, 3 ductal carcinoma in situ and 3 invasive ductal carcinoma samples revealed that there was no change in EP2 promoter methylation status between normal and cancer associated stroma, despite observed differences in relative mRNA levels. Although EP2 methylation status is inversely correlated to expression levels in established breast cancer cell lines, we could not identify that such a correlation existed in tumour-associated stroma cells. 相似文献
76.
Epoxycarotenoid cleavage by NCED5 fine-tunes ABA accumulation and affects seed dormancy and drought tolerance with other NCED family members 总被引:1,自引:0,他引:1
Frey A Effroy D Lefebvre V Seo M Perreau F Berger A Sechet J To A North HM Marion-Poll A 《The Plant journal : for cell and molecular biology》2012,70(3):501-512
Carotenoid cleavage, catalyzed by the 9-cis-epoxycarotenoid dioxygenase (NCED) constitutes a key step in the regulation of ABA biosynthesis. In Arabidopsis, this enzyme is encoded by five genes. NCED3 has been shown to play a major role in the regulation of ABA synthesis in response to water deficit, whereas NCED6 and NCED9 have been shown to be essential for the ABA production in the embryo and endosperm that imposes dormancy. Reporter gene analysis was carried out to determine the spatiotemporal pattern of NCED5 and NCED9 gene expression. GUS activity from the NCED5 promoter was detected in both the embryo and endosperm of developing seeds with maximal staining after mid-development. NCED9 expression was found at early stages in the testa outer integument layer 1, and after mid-development in epidermal cells of the embryo, but not in the endosperm. In accordance with its temporal- and tissue-specific expression, the phenotypic analysis of nced5 nced6 nced9 triple mutant showed the involvement of the NCED5 gene, together with NCED6 and NCED9, in the induction of seed dormancy. In contrast to nced6 and nced9, however, nced5 mutation did not affect the gibberellin required for germination. In vegetative tissues, combining nced5 and nced3 mutations reduced vegetative growth, increased water loss upon dehydration, and decreased ABA levels under both normal and stressed conditions, as compared with nced3. NCED5 thus contributes, together with NCED3, to ABA production affecting plant growth and water stress tolerance. 相似文献
77.
78.
Ho Dang Trung N Le Thi Phuong T Wolbers M Nguyen Van Minh H Nguyen Thanh V Van MP Thieu NT Van TL Song DT Thi PL Thi Phuong TN Van CB Tang V Ngoc Anh TH Nguyen D Trung TP Thi Nam LN Kiem HT Thi Thanh TN Campbell J Caws M Day J de Jong MD Van Vinh CN Van Doorn HR Tinh HT Farrar J Schultsz C;VIZIONS CNS Infection Network 《PloS one》2012,7(5):e37825
79.
Jürgen Brem Mihaela C. TurcuCsaba Paizs Katri LundellMonica-Ioana To?a Florin-Dan IrimieLiisa T. Kanerva 《Process Biochemistry》2012,47(1):119-126
Lipase AK “Amano” 20 from Pseudomonas fluorescens (PFL) was immobilized using diverse immobilization techniques. The methods developed, especially the optimized sol-gel procedure, enabled the fine tuning of enzymatic activity and enantioselectivity for the kinetic resolution of racemic ethyl 3-aryl-3-hydroxypropanoates. The aryl moieties of the racemates include furan-2 and 3-yl, thiophen-2 and 3-yl, benzofuran-2-yl, benzo[b]thiophen-2-yl, as well as phenyl and 4-chloro- and 4-methoxyphenyl groups. The optimized PFL sol-gel preparation (encapsulation from the aqueous solution of PFL, sucrose and Celite in situ) was shown to be efficiently reusable in ten cycles and highly enantioselective with E > 200 to all other substrates except furan-2 and 3-yl and thiophen-2 and 3-yl substituted compounds with E 108-184. 相似文献
80.