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991.
V. Nöthig-Laslo I. Weygand-Durasević Zeljko Kućan 《Journal of biomolecular structure & dynamics》2013,31(5):941-951
Abstract The existence of specific sites in tRNA for the binding of divalent cations has been seriously questioned by electrostatic considerations [Leroy & Guéron (1979) Biopolymers, 16, 2429–2446], However, our earlier studies of the binding of Mg2+ and Mn2+ to yeast tRNATyr have indicated that spermine creates new binding sites for divalent cations [Weygand-Durasevi? et al. (1977) Biochim. Biophys. Acta, 479, 332–344; Nöthig-Laslo et al. (1981) Eur. J. Biochem. 117, 263–267]. We have now used yeast tRNATyr, spin labeled at the hypermodified purine (i6A-37) in the anticodon loop, to study the effect of spermine on the binding of manganese ions. The presence of eight spermine molecules per tRNATyr at high ionic strength (0.2 M NaCl, 0.05 M triethanolamine-HCl) and at low temperature (7°C) enhances the binding of manganese to tRNATyr. This effect could not be explained by electrostatic binding. The initial binding of manganese to tRNATyr affects the motional properties of the spin label indicating a change of the conformation of the anticodon loop. From the absence of the paramagnetic effect of manganese on the ESR spectra of the spin label one can conclude that the first binding site for manganese is at a distance from i6A-37, influencing the spin label motion through a long-range effect. The enhancement of the binding of manganese to tRNATyr by spermine is lost upon destruction of its specific macromolecular structure and it does not occur in single stranded or in double-stranded polynucleotides. The observed effect can be explained by the binding of Mn2+ to new sites, created by the binding of spermine, which are specific for the macromolecular structure of tRNA. 相似文献
992.
Juliana O.S. Giacoppo Tanos C.C. França Kamil Kuča Elaine F.F. da Cunha Ruben Abagyan Daiana T. Mancini 《Journal of biomolecular structure & dynamics》2013,31(9):2048-2058
Nerve agents are organophosphates acting as potent inhibitors of acetylcholinesterase (AChE), the enzyme responsible for the hydrolysis of acetylcholine and, consequently, the termination of the transmission of nerve impulses. The inhibition of AChE by an organophosphate can be reversed by a nucleophilic agent able to dephosphorylate a serine residue in the active site of AChE. In this sense, the oximes are compounds capable of removing the nerve agent and reactivate the enzyme. Here, we have applied a methodology involving theoretical docking and Quantum Mechanics/Molecular Mechanics, using the softwares Molegro® and Spartan®, to evaluate the kinetic constants of reactivation and the interactions of the oxime BI-6 with AChE inhibited by different organophosphorus compounds in comparison to in vitro data. Results confirm that this method is suitable for the prediction of kinetic and thermodynamic parameters of oximes, which may be useful in the design and selection of new and more effective oximes. 相似文献
993.
Chai Siah Ku Tho X. Pham Youngki Park Bohkyung Kim Min Sun Shin Insoo Kang Jiyoung Lee 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Chronic inflammation contributes to the development of pathological disorders including insulin resistance and atherosclerosis. Identification of anti-inflammatory natural products can prevent the inflammatory diseases.Methods
Anti-inflammatory effects of blue-green algae (BGA), i.e., Nostoc commune var. sphaeroides Kützing (NO) and Spirulina platensis (SP), were compared in RAW 264.7 and mouse bone marrow-derived macrophages (BMM) as well as splenocytes from apolipoprotein E knockout (apoE−/−) mice fed BGA.Results
When macrophages pretreated with 100 μg/ml NO lipid extract (NOE) or SP lipid extract (SPE) were activated by lipopolysaccharide (LPS), expression and secretion of pro-inflammatory cytokines, such as tumor necrosis factor α (TNFα), interleukin 1β (IL-1β), and IL-6, were significantly repressed. NOE and SPE also significantly repressed the expression of TNFα and IL-1β in BMM. LPS-induced secretion of IL-6 was lower in splenocytes from apoE−/− fed an atherogenic diet containing 5% NO or SP for 12 weeks. In RAW 264.7 macrophages, NOE and SPE markedly decreased nuclear translocation of NF-κB. The degree of repression of pro-inflammatory gene expression by algal extracts was much stronger than that of SN50, an inhibitor of NF-κB nuclear translocation. Trichostatin A, a pan histone deacetylase inhibitor, increased basal expression of IL-1β and attenuated the repression of the gene expression by SPE. SPE significantly down-regulated mRNA abundance of 11 HDAC isoforms, consequently increasing acetylated histone 3 levels.Conclusion
NOE and SPE repress pro-inflammatory cytokine expression and secretion in macrophages and splenocytes via inhibition of NF-κB pathway. Histone acetylation state is likely involved in the inhibition.General significance
This study underscores natural products can exert anti-inflammatory effects by epigenetic modifications such as histone acetylation. 相似文献994.
Jeffry D. Sander Cherie L. Ramirez Samantha J. Linder Vikram Pattanayak Noam Shoresh Manching Ku Jennifer A. Foden Deepak Reyon Bradley E. Bernstein David R. Liu J. Keith Joung 《Nucleic acids research》2013,41(19):e181
Gene-editing nucleases enable targeted modification of DNA sequences in living cells, thereby facilitating efficient knockout and precise editing of endogenous loci. Engineered nucleases also have the potential to introduce mutations at off-target sites of action. Such unintended alterations can confound interpretation of experiments and can have implications for development of therapeutic applications. Recently, two improved methods for identifying the off-target effects of zinc finger nucleases (ZFNs) were described–one using an in vitro cleavage site selection method and the other exploiting the insertion of integration-defective lentiviruses into nuclease-induced double-stranded DNA breaks. However, application of these two methods to a ZFN pair targeted to the human CCR5 gene led to identification of largely non-overlapping off-target sites, raising the possibility that additional off-target sites might exist. Here, we show that in silico abstraction of ZFN cleavage profiles obtained from in vitro cleavage site selections can greatly enhance the ability to identify potential off-target sites in human cells. Our improved method should enable more comprehensive profiling of ZFN specificities. 相似文献
995.
Milan Oldřich Urban Miroslav KlímaPavel Vítámvás Jakub VašekAlois Albert Hilgert-Delgado Vratislav Kučera 《Journal of plant physiology》2013
Five winter oilseed rape cultivars (Benefit, Californium, Cortes, Ladoga, Navajo) were subjected to 30 days of cold treatment (4 °C) to examine the effect of cold on acquired frost tolerance (FT), dehydrin (DHN) content, and photosynthesis-related parameters. The main aim of this study was to determine whether there are relationships between FT (expressed as LT50 values) and the other parameters measured in the cultivars. While the cultivar Benefit accumulated two types of DHNs (D45 and D35), the other cultivars accumulated three additional DHNs (D97, D47, and D37). The similar-sized DHNs (D45 and D47) were the most abundant; the others exhibited significantly lower accumulations. The highest correlations were detected between LT50 and DHN accumulation (r = −0.815), intrinsic water use efficiency (WUEi; r = −0.643), net photosynthetic rate (r = −0.628), stomatal conductance (r = 0.511), and intracellular/intercellular CO2 concentration (r = 0.505). Those cultivars that exhibited higher Pn rate in cold (and further a significant increase in WUEi) had higher levels of DHNs and also higher FT. No significant correlation was observed between LT50 and E, PRI, or NDVI. Overall, we have shown the selected physiological parameters to be able to distinguish different FT cultivars of winter oilseed rape. 相似文献
996.
Iso-Touru Terhi Huitu Otso Tapio Miika Kučinskienė Jūratė Ulevičius Alius Bukelskis Egidijus Tirronen Konstantin Fyodorov Fyodor Panchenko Danila Saarma Urmas Valdmann Harri Kauhala Kaarina 《Acta theriologica》2020,65(2):331-338
Mammal Research - Reduction of genetic diversity can lead to reduced fitness of species, such as the loss of adaptability to changing environments. The native Eurasian beaver (Castor fiber) was... 相似文献
997.
998.
The effects of the metabolic inhibitors KCN and SHAM on phototaxis and photophobic response in Amoeba proteus have been studied. Both drugs neither change amoebae photophobic response nor the phototactic reaction. The results indicate clearly that the negative phototactic orientation is not impaired by impediment of respiration thus it is not directly coupled to the differences in energy production in different parts of A. proteus body. 相似文献
999.
Structural changes of yeast tRNA(Tyr) caused by the binding of divalent ions in the presence of spermine 总被引:1,自引:0,他引:1
V N?thig-Laslo I Weygand-Durasevi? Z Ku?an 《Journal of biomolecular structure & dynamics》1985,2(5):941-951
The existence of specific sites in tRNA for the binding of divalent cations has been seriously questioned by electrostatic considerations [Leroy & Guéron (1979) Biopolymers, 16, 2429-2446]. However, our earlier studies of the binding of Mg2+ and Mn2+ to yeast tRNA(Tyr) have indicated that spermine creates new binding sites for divalent cations [Weygand-Durasevi? et al. (1977) Biochim. Biophys, Acta, 479, 332-344; N?thig-Laslo et al. (1981) Eur. J. Biochem. 117, 263-267]. We have now used yeast tRNA(Tyr), spin labeled at the hypermodified purine (i6A-37) in the anticodon loop, to study the effect of spermine on the binding of manganese ions. The presence of eight spermine molecules per tRNA(Tyr) at high ionic strength (0.2 M NaCl, 0.05 M triethanolamine.HCl) and at low temperature (7 degrees C) enhances the binding of manganese to tRNA(Tyr). This effect could not be explained by electrostatic binding. The initial binding of manganese to tRNA(Tyr) affects the motional properties of the spin label indicating a change of the conformation of the anticodon loop. From the absence of the paramagnetic effect of manganese on the ESR spectra of the spin label one can conclude that the first binding site for manganese is at a distance from i6A-37, influencing the spin label motion through a long-range effect. The enhancement of the binding of manganese to tRNA(Tyr) by spermine is lost upon destruction of its specific macromolecular structure and it does not occur in single stranded or in double-stranded polynucleotides. The observed effect can be explained by the binding of Mn2+ to new sites, created by the binding of spermine, which are specific for the macromolecular structure of tRNA. 相似文献
1000.
The activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSP) as well as of succinate dehydrogenase (SDG), NADH dehydrogenase (NDG) and fumarate hydratase (FHT) were examined in relation to mitochondrial ultrastructure changes in Aspergillus niger exposed to N,N-bis(3-aminopropyl)dodecylamine (Apd) that was shown to exhibit fungicidal activity. There was a progressive increase in SOD, CAT and GSP activities 1 and 4 h after 0.05 and 0.1 % Apd application. However, this was followed by a pronounced activity decrease when 0.05 % Apd treatment was prolonged by 1 d. The destructive effect on fungal morphology was observed when this fungicidal agent was applied at the concentration of 0.1 % for 1 d. In the treated hyphae mitochondria degenerated after all organelles. The morphological malformations of mitochondria had an impact on their metabolic state; however, the activities of SDG, NDG and FHT were affected to a different extent. In A. niger the fungicidal effect of Apd could be mediated by oxidative stress impairing the vital mitochondria-related cellular functions. 相似文献