共查询到20条相似文献,搜索用时 15 毫秒
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E. Yu. Aleshina N. V. Pyndyk A. A. Moisa M. A. Sanzhakov O. N. Kharybin E. N. Nikolaev E. F. Kolesanova 《Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry》2008,2(3):288-292
The peptide RHDSGY, a fragment of the human β-amyloid Zn-binding site, and its isomers RH(D-Asp)SGY and RH(β-Asp)SGY have been obtained as amides by means of solid-phase synthesis and analyzed by HPLC and various mass spectrometric methods. The problem of low yield of the RHDSGY peptide and its isomers attributed to 9-fluorenylmethoxycarbonyl (Fmoc)-amino acids and/or formation of such side-products as RH(β-Asp)SGY (or RHDSGY during synthesis of RH(β-Asp)SGY) and RH(Asp-imide) SGY was solved via selection of individual reagents for removal of Fmoc groups from α-amino groups of the growing peptide chain. 相似文献
3.
We present two NMR experiments, (3,2)D HNHA and (3,2)D HNHB, for rapid and accurate measurement of 3J(H N-H alpha) and 3J(N-H beta) coupling constants in polypeptides based on the principle of G-matrix Fourier transform NMR spectroscopy and quantitative J-correlation. These experiments, which facilitate fast acquisition of three-dimensional data with high spectral/digital resolution and chemical shift dispersion, will provide renewed opportunities to utilize them for sequence specific resonance assignments, estimation/characterization of secondary structure with/without prior knowledge of resonance assignments, stereospecific assignment of prochiral groups and 3D structure determination, refinement and validation. Taken together, these experiments have a wide range of applications from structural genomics projects to studying structure and folding in polypeptides. 相似文献
4.
M. A. Breygina N. P. Matveyeva D. S. Andreyuk I. P. Yermakov 《Russian Journal of Developmental Biology》2012,43(2):85-93
We studied the possibility of K+ and Cl− efflux from tobacco pollen grains during their activation in vitro or on the stigma of a pistil. For this purpose the X-ray
microanalysis and spectrofluorometry were applied. We found that the relative content of potassium and chlorine in the microvolume
of pollen grain decreases during its hydration and activation on stigma. Efflux of these ions was found both in vivo and in
vitro. In model in vitro experiments anion channel inhibitor NPPB ((5-nitro-2-(3-phenylpropylamino) benzoic acid) in the concentration
that was blocking pollen germination, reduced Cl− efflux; potassium channel inhibitor TEA (tetraethylammonium chloride) partially reduced K+ efflux and lowered the percent of activated cells. Another blocker of potassium channels Ba2+ caused severe decrease in cell volume and blocked the activation. In general, the obtained data demonstrates that the initiation
of pollen germination both in vivo and in vitro involves the activation of K+ and Cl− release. An important role in these processes is played by NPPB-, TEA- and Ba2+-sensitive plasmalemma ion channels. 相似文献
5.
Microarrays are a powerful tool for comparison and understanding of gene expression levels in healthy and diseased states. The method relies upon the assumption that signals from microarray features are a reflection of relative gene expression levels of the cell types under investigation. It has previously been reported that the classical fluorescent dyes used for microarray technology, Cy3 and Cy5, are not ideal due to the decreased stability and fluorescence intensity of the Cy5 dye relative to the Cy3, such that dye bias is an accepted phenomena necessitating dye swap experimental protocols and analysis of differential dye affects. The incentive to find new fluorophores is based on alleviating the problem of dye bias through synonymous performance between counterpart dyes. Alexa Fluor 555 and Alexa Fluor 647 are increasingly promoted as replacements for CyDye in microarray experiments. Performance relates to the molecular and steric similarities, which will vary for each new pair of dyes as well as the spectral integrity for the specific application required. Comparative analysis of the performance of these two competitive dye pairs in practical microarray applications is warranted towards this end. The findings of our study showed that both dye pairs were comparable but that conventional CyDye resulted in significantly higher signal intensities (P < 0.05) and signal minus background levels (P < 0.05) with no significant difference in background values (P > 0.05). This translated to greater levels of differential gene expression with CyDye than with the Alexa Fluor counterparts. However, CyDye fluorophores and in particular Cy5, were found to be less photostable over time and following repeated scans in microarray experiments. These results suggest that precautions against potential dye affects will continue to be necessary and that no one dye pair negates this need. 相似文献
6.
Based on the difference in the CD14 and CD16 expression, two subsets of monocytes were identified in human and other mammalian
blood. These subsets have different patterns of adhesion molecules and chemokine receptors that suggests the different mode
of their interaction with endothelium and tissue traffic. Here, we investigated the ability of CD14+CD16+ and CD14++CD16− monocytes to adhere to endothelial cell monolayer in presence or absence of pro- and anti-inflammatory cytokines. We demonstrated
that CD14+CD16+ monocytes had a higher level of adhesion to intact monolayer of endothelial cells than CD14++CD16− monocytes. Adhesion of CD14++CD16− and CD14+CD16+ monocytes significantly increased in the presence of TNFα or its combination with other cytokines. IFNγ and IL-4 alone did
not affect the adhesion of monocytes. These results show that CD14++CD16− and CD14+CD16+ monocytes can be recruited to the inflamed endothelium, but CD14+CD16+ monocytes adhere to endothelial cells without inflammations twice as strongly as CD14++CD16− monocytes. 相似文献
7.
The rat major histocompatibility complex loci RT1-B and RT1-D are equivalent to the human leucocyte antigens HLA-DQ and HLA-DR respectively. Here we describe the complementary DNA (cDNA) sequence encoding the and chains of both the RT1-B and RT1-D locus genes of the rat RT1u haplotype. We have found entire sequence identity between five different inbred rat strains of the RT1u haplotype, which differs from previously published, incomplete sequences. This information is of considerable value for experimental studies of transplantation immunity and autoimmune disease.Nucleotide sequences reported in this paper have been submitted to the EMBL nucleotide sequence database and have been assigned the accession numbers AJ554214 (RT1-Bua), AJ554215 (RT1-Bub) and AJ554216 (RT1-Dua). 相似文献
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Martin D. Gelenter Tuo Wang Shu-Yu Liao Hugh O’Neill Mei Hong 《Journal of biomolecular NMR》2017,68(4):257-270
Site-specific determination of molecular motion and water accessibility by indirect detection of 2H NMR spectra has advantages over dipolar-coupling based techniques due to the large quadrupolar couplings and the ensuing high angular resolution. Recently, a Rotor Echo Short Pulse IRrAdiaTION mediated cross polarization (RESPIRATIONCP) technique was developed, which allowed efficient transfer of 2H magnetization to 13C at moderate 2H radiofrequency field strengths available on most commercial MAS probes. In this work, we investigate the 2H–13C magnetization transfer characteristics of one-bond perdeuterated CD n spin systems and two-bond H/D exchanged C–(O)–D and C–(N)–D spin systems in carbohydrates and proteins. Our results show that multi-bond, broadband 2H–13C polarization transfer can be achieved using 2H radiofrequency fields of ~50 kHz, relatively short contact times of 1.3–1.7 ms, and with sufficiently high sensitivity to enable 2D 2H–13C correlation experiments with undistorted 2H spectra in the indirect dimension. To demonstrate the utility of this 2H–13C technique for studying molecular motion, we show 2H–13C correlation spectra of perdeuterated bacterial cellulose, whose surface glucan chains exhibit a motionally averaged C6 2H quadrupolar coupling that indicates fast trans-gauche isomerization about the C5–C6 bond. In comparison, the interior chains in the microfibril core are fully immobilized. Application of the 2H–13C correlation experiment to H/D exchanged Arabidopsis primary cell walls show that the O–D quadrupolar spectra of the highest polysaccharide peaks can be fit to a two-component model, in which 74% of the spectral intensity, assigned to cellulose, has a near-rigid-limit coupling, while 26% of the intensity, assigned to matrix polysaccharides, has a weakened coupling of 50 kHz. The latter O–D quadrupolar order parameter of 0.22 is significantly smaller than previously reported C–D dipolar order parameters of 0.46–0.55 for pectins, suggesting that additional motions exist at the C–O bonds in the wall polysaccharides. 2H–13C polarization transfer profiles are also compared between statistically deuterated and H/D exchanged GB1. 相似文献
10.
Nishit Goradia Amelie Wißbrock Christoph Wiedemann Frank Bordusa Ramadurai Ramachandran Diana Imhof Oliver Ohlenschläger 《Biomolecular NMR assignments》2016,10(2):329-333
Interleukin-36α (IL-36α) is a recently characterised member of the interleukin-1 superfamily. It is involved in the pathogenesis of inflammatory arthritis in one third of psoriasis patients. By binding of IL-36α to its receptor IL-36R via the NF-κB pathway other cytokines involved in inflammatory and apoptotic cascade are activated. The efficacy of complex formation is controlled by N-terminal processing. To obtain a more detailed view on the structure function relationship we performed a heteronuclear multidimensional NMR investigation and here report the 1H, 13C, and 15N resonance assignments for the backbone and side chain nuclei of the pro-inflammatory cytokine interleukin-36α. 相似文献
11.
The structures and stabilities of eleven N13
+ and N13
– isomers have been investigated with second-order Møller–Plesset (MP2) and density functional theory (DFT) methods. Five N13
+ isomers and six N13
– isomers are all reasonable local minima on their potential energy hypersurfaces. The most stable N13
+ cation is structure C-2 with C2v symmetry, which contains a pentazole ring and two N4 open chains. It is different from those of the N7
+ and N9
+ clusters, but similar to the N11
+ cluster. Meanwhile, the most stable N13
– structure A-2 is composed of a pentazole ring and a six-membered ring connected by two nitrogen atoms. It is not only different from those of the N7
– and N9
– clusters, but also from the N11
– cluster. The decomposition pathways of structures C-2 and A-2 were investigated at the B3LYP/(aug)-cc-pVDZ level. From the barrier heights of the structures C-2 and A-2 decomposition processes, it is suggested that C-2 is difficult to observe experimentally and A-2 may be observed as a short-lived species.
Figure Optimized geometrical parameters of N13
+ isomer C-2
相似文献
12.
Seasonal oscillations in the carbon (δ13C) and nitrogen (δ15N) isotope signatures of aquatic algae can cause seasonal enrichment–depletion cycles in the isotopic composition of planktonic
invertebrates (e.g., copepods). Yet, there is growing evidence that seasonal enrichment–depletion cycles also occur in the
isotope signatures of larger invertebrate consumers, taxa used to define reference points in isotope-based trophic models
(e.g., trophic baselines). To evaluate the general assumption of temporal stability in non-zooplankton aquatic invertebrates,
δ13C and δ15N time series data from the literature were analyzed for seasonality and the influence of biotic (feeding group) and abiotic
(trophic state, climate regime) factors on isotope temporal patterns. The amplitude of δ13C and δ15N enrichment–depletion cycles was negatively related to body size, although all size-classes of invertebrates displayed a
winter-to-summer enrichment in δ13C and depletion in δ15N. Among feeding groups, periphytic grazers were more variable and displayed larger temporal changes in δ13C than detritivores. For nitrogen, temporal variability and magnitude of directional change of δ15N was most strongly related to ecosystem trophic state (eutrophic > mesotrophic, oligotrophic). This study provides evidence
of seasonality in the isotopic composition of aquatic invertebrates across very broad geographical and ecological gradients
as well as identifying factors that are likely to modulate the strength and variability of seasonality. These results emphasize
the need for researchers to recognize the likelihood of temporal changes in non-zooplankton aquatic invertebrate consumers
at time scales relevant to seasonal studies and, if present, to account for temporal dynamics in isotope trophic models. 相似文献
13.
Murakami D Suzuki MF da Silva Dias M Okazaki K 《Radiation and environmental biophysics》2004,43(2):91-99
Among various types of ionizing radiation, the beta emitter radionuclides are involved in many sectors of human activity, such as nuclear medicine, nuclear industries and biomedicine, with a consequently increased risk of accidental, occupational or therapeutic exposure. Despite their recognized importance, there is little information about the effect of beta particles at the cellular level when compared to other types of ionizing radiation. Thus, the objective of the present study was to evaluate the genotoxic and cytotoxic effects of 90Sr/90Y—a pure, highly energetic beta source—on Chinese hamster ovary (CHO) cells and to compare them with data obtained with 60Co. CHO cells irradiated with different doses of 60Co (0.34 Gy min–1) and 90Sr/90Y (0.23 Gy min–1) were processed for analysis of clonogenic death, induction of micronuclei (MN) and interphase death. The survival curves obtained for both types of radiation were fitted by the exponential quadratic model and were found to be similar. Also, the cytogenetic results showed similar frequencies of radio-induced MN between gamma and beta radiations and the MN distribution pattern among cells did not follow the expected Poisson probability pattern. The relative variance values were significantly higher in cells irradiated with 90Sr/90Y than with 60Co in all exposure doses. The irradiated cells showed more necrotic cells 72 h and 96 h after exposure to beta than to gamma radiation. In general, the 90Sr/90Y -radiation was more damaging than 60Co -rays. The data obtained also demonstrated the need to use several parameters for a better estimate of cellular sensitivity to the action of genotoxic agents, which would be important in terms of radiobiology, oncology and therapeutics. 相似文献
14.
Negative impacts exerted by sodium (Na+) and chloride (Cl?) ions individually as well their possible additive effects (under NaCl) were evaluated on growth and yield reductions in rice, besides investigating whether salt-tolerant genotypes respond differentially than their sensitive counterparts. Though both Na+ and Cl? ions get accumulated in plant tissues under NaCl stress, most research has historically been aimed to decipher harmful effects induced by Na+ ions. Accordingly, physiological and molecular mechanisms involved in Cl? toxicity are not clearly understood in crop plants. To address these issues, 65-day-old plants of two rice cultivars, Panvel-3 (tolerant) and Sahyadri-3 (sensitive) were subjected to Cl?, Na+ and NaCl (each with 100 mM concentration and electrical conductivity of ≈10 dS m?1) stress using soil-based systems. Stress conditions were maintained till harvesting of mature (128-day-old) plants. All three treatments induced substantial antagonistic effects on growth, dry mass, yield components (number of grains per panicle, length, width, thickness and weight of grain, along with the percentage of grains filled) and overall crop yield, with greater impacts under NaCl than its constituent ions. Salinity treatments caused an imbalance in reducing sugars, protein, starch and proline contents, with the greatest magnitude under NaCl. A negative correlation between Cl?/Na+ accumulation and crop yield was witnessed, with higher severity on the sensitive cultivar. The overall magnitude of toxicity was observed highest in NaCl followed by Na+ and Cl?, respectively, suggesting additive effects of constituent ions under NaCl. Both cultivars responded similarly; however, the tolerant cultivar, unlike the sensitive one, kept Na+:K+ ratio <1.0 and accumulated proline in response to salinity treatments used in this study. 相似文献
15.
MEMBRANE enzymes, because of their lipid content, are insoluble in water and usually solubilized as micelles in aqueous solution by detergents for biochemical study. Direct study of lipid components by means of organic liquids in which they dissolve leads at once to the denaturation of the enzyme. At temperatures appreciably colder than 0° C, however, organic solvents may leave enzymatic activity intact1–3, making it possible to study enzyme reactions. 相似文献
16.
In two mountain ecosystems at the Alptal research site in central Switzerland, pulses of 15NO3 and 15NH4 were separately applied to trace deposited inorganic N. One forested and one litter meadow catchment, each approximately
1600 m2, were delimited by trenches in the Gleysols. K15NO3 was applied weekly or fortnightly over one year with a backpack sprayer, thus labelling the atmospheric nitrate deposition.
After the sampling and a one-year break, 15NH4Cl was applied as a second one-year pulse, followed by a second sampling campaign. Trees (needles, branches and bole wood),
ground vegetation, litter layer and soil (LF, A and B horizon) were sampled at the end of each labelling period. Extractable
inorganic N, microbial N, and immobilised soil N were analysed in the LF and A horizons. During the whole labelling period,
the runoff water was sampled as well. Most of the added tracer remained in both ecosystems. More NO3− than NH4+ tracer was retained, especially in the forest. The highest recovery was in the soil, mainly in the organic horizon, and in
the ground vegetation, especially in the mosses. Event-based runoff analyses showed an immediate response of 15NO3− in runoff, with sharp 15N peaks corresponding to discharge peaks. NO3− leaching showed a clear seasonal pattern, being highest in spring during snowmelt. The high capacity of N retention in these
ecosystems leads to the assumption that deposited N accumulates in the soil organic matter, causing a progressive decline
of its C:N ratio. 相似文献
17.
Arginine side-chains are often key for enzyme catalysis, protein–ligand and protein–protein interactions. The importance of arginine stems from the ability of the terminal guanidinium group to form many key interactions, such as hydrogen bonds and salt bridges, as well as its perpetual positive charge. We present here an arginine 13Cζ-detected NMR experiment in which a double-quantum coherence involving the two 15Nη nuclei is evolved during the indirect chemical shift evolution period. As the precession frequency of the double-quantum coherence is insensitive to exchange of the two 15Nη; this new approach is shown to eliminate the previously deleterious line broadenings of 15Nη resonances caused by the partially restricted rotation about the Cζ–Nε bond. Consequently, sharp and well-resolved 15Nη resonances can be observed. The utility of the presented method is demonstrated on the L99A mutant of the 19 kDa protein T4 lysozyme, where the measurement of small chemical shift perturbations, such as one-bond deuterium isotope shifts, of the arginine amine 15Nη nuclei becomes possible using the double-quantum experiment. 相似文献
18.
The widespread use of β-lactam antibiotics has given rise to a dramatic increase in clinically-relevant β-lactamases. Understanding the structure/function relation in these variants is essential to better address the ever-growing incidence of antibiotic resistance. We previously reported the backbone resonance assignments of a chimeric protein constituted of segments of the class A β-lactamases TEM-1 and PSE-4 (Morin et al. in Biomol NMR Assign 4:127–130, 2010. doi: 10.1007/s12104-010-9227-8). That chimera, cTEM17m, held 17 amino acid substitutions relative to TEM-1 β-lactamase, resulting in a well-folded and fully functional protein with increased dynamics. Here we report the 1H, 13C and 15N backbone resonance assignments of chimera cTEM-19m, which includes 19 substitutions and exhibits increased active-site perturbation, as well as one of its deconvoluted variants, as the first step in the analysis of their dynamic behaviours. 相似文献
19.