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1.
A series of 11 α,ω-diaminoalkanes, (H 2N(CH 2) nNH 2, n = 2–12) have been evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis H37Rv. Compounds, (H 2N(CH 2) nNH 2, n = 9–12), exhibited a very good activities in the range 2.50–3.12 μg/mL, which can be compared with that of the first line drug, ethambutol (3.12 μg/mL). These results and a preliminary QSAR study can be considered an important start point for the rational design of new leads for anti-TB compounds. 相似文献
3.
A methylene group in the fluorinated carbon backbone of 1H,1H,2H,2H,8H,8H–perfluorododecanol (degradable telomer fluoroalcohol, DTFA) renders the molecule cleavable by microbial degradation into two fluorinated carboxylic acids. Several biodegradation products of DTFA are known, but their rates of conversion and fates in the environment have not been determined. We used liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) to quantitatively investigate DTFA biodegradation by the microbial community in activated sludge in polyethylene terephthalate (PET) flasks, which we also determined here showed least adsorption of DTFA. A reduction in DTFA concentration in the medium was accompanied by rapid increases in the concentrations of 2H,2H,8H,8H–perfluorododecanoic acid (2H,2H,8H,8H–PFDoA), 2H,8H,8H-2-perfluorododecenoic acid (2H,8H,8H-2-PFUDoA), and 2H,2H,8H-7-perfluorododecenoic acid and 2H,2H,8H-8-perfluorododecenoic acid (2H,2H,8H-7-PFUDoA/2H,2H,8H-8-PFUDoA), which were in turn followed by an increase in 6H,6H–perfluorodecanoic acid (6H,6H–PFDeA) concentration, and decreases in 2H,2H,8H,8H–PFDoA, 2H,8H,8H-2-PFUDoA, and 2H,2H,8H-7-PFUDoA/2H,2H,8H-8-PFUDoA concentrations. Accumulation of perfluorobutanoic acid (PFBA), a presumed end product of DTFA degradation, was also detected. Our quantitative and time-course study of the concentrations of these compounds reveals main routes of DTFA biodegradation, and the presence of new biodegradation pathways. 相似文献
4.
BackgroundAnnual seasonal influenza outbreaks are associated with high morbidity and mortality. ObjectiveTo index and document evolutionary changes among influenza A H1N1 and H3N2 viruses isolated from Thailand during 2006–2009, using complete genome sequences. MethodsNasopharyngeal aspirates were collected from patients diagnosed with respiratory illness in Thailand during 2006–2009. All samples were screened for Influenza A virus. A total of 13 H1N1 and 21 H3N2 were confirmed and whole genome sequenced for the evolutionary analysis using standard phylogenetic approaches. ResultsPhylogenetic analysis of HA revealed a clear diversification of seasonal from vaccine strain lineages. H3N2 seasonal clusters were closely related to the WHO recommended vaccine strains in each season. Most H1N1 isolates could be differentiated into 3 lineages. The A/Brisbane/59/2007 lineage, a vaccine strain for H1N1 since 2008, is closely related with the H1N1 subtypes circulating in 2009. HA sequences were conserved at the receptor-binding site. Amino acid variations in the antigenic site resulted in a possible N-linked glycosylation motif. Recent H3N2 isolates had higher genetic variations compared to H1N1 isolates. Most substitutions in the NP protein were clustered in the T-cell recognition domains. ConclusionIn this study we performed evolutionary genetic analysis of influenza A viruses in Thailand between 2006–2009. Although the current vaccine strain is efficient for controlling the circulating outbreak subtypes, surveillance is necessary to provide unambiguous information on emergent viruses. In summary, the findings of this study contribute the understanding of evolution in influenza A viruses in humans and is useful for routine surveillance and vaccine strain selection. 相似文献
5.
Tyrosinase catalyzes the ortho hydroxylation of monophenols and the subsequent oxidation of the diphenolic products to the resulting quinones. In efforts
to create biomimetic copper complexes that can oxidize C–H bonds, Stack and coworkers recently reported a synthetic μ-η 2:η 2-peroxodicopper(II)(DBED) 2 complex (DBED is N, N′-di- tert-butylethylenediamine), which rapidly hydroxylates phenolates. A reactive intermediate consistent with a bis-μ-oxo-dicopper(III)-phenolate
complex, with the O–O bond fully cleaved, is observed experimentally. Overall, the evidence for sequential O–O bond cleavage
and C–O bond formation in this synthetic complex suggests an alternative mechanism to the concerted or late-stage O–O bond
scission generally accepted for the phenol hydroxylation reaction performed by tyrosinase. In this work, the reaction mechanism
of this peroxodicopper(II) complex was studied with hybrid density functional methods by replacing DBED in the μ-η 2:η 2-peroxodicopper(II)(DBED) 2 complex by N, N′-dimethylethylenediamine ligands to reduce the computational costs. The reaction mechanism obtained is compared with the
existing proposals for the catalytic ortho hydroxylation of monophenol and the subsequent oxidation of the diphenolic product to the resulting quinone with the aim
of gaining some understanding about the copper-promoted oxidation processes mediated by 2:1 Cu(I)O 2-derived species.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
6.
This paper describes a [ 15N, 1H]/[ 13C, 1H]-TROSY experiment for the simultaneous acquisition of the heteronuclear chemical shift correlations of backbone amide 15N– 1H groups, side chain 15N– 1H 2 groups and aromatic 13C– 1H groups in otherwise highly deuterated proteins. The 15N– 1H and 13C– 1H correlations are extracted from two subspectra of the same data set, thus preventing possible spectral overlap of aromatic and amide protons in the 1H dimension. The side-chain 15N– 1H 2 groups, which are suppressed in conventional [ 15N, 1H)-TROSY, are observed with high sensitivity in the 15N– 1H subspectrum. [ 15N, 1H]/[ 13C, 1H]-TROSY was used as the heteronuclear correlation block in a 3D [ 1H, 1H]-NOESY-[ 15N, 1H]/[ 13C, 1H]-TROSY experiment with the membrane protein OmpA reconstituted in detergent micelles of molecular weight 80000 Da, which enabled the detection of numerous NOEs between backbone amide protons and both aromatic protons and side chain 15N– 1H 2 groups. 相似文献
8.
Nitrogen fixation in excised root nodules of 2-year-old, postfire Ceanothus tomentosus and C. leucodermis seedlings was measured over an 8-month period using the acetylene reduction method. High levels of NO 3–N and NH 4–N present in postfire soils were limited to the upper 10 cm and did not inhibit nodulation in these deeper-rooting seedlings. Decreases in acetylene reduction activity occurred with decreased soil moisture and increased soil temperature. Nitrogen gains from these two Ceanothus shrub seedlings totalled 1.6 kg N ha –1 yr –1. 相似文献
9.
The rate laws for the earliest events in the transmetalation of dimeric copper(I) complexes L 2Cu 2X 2 (L = N,N,N′N′-tetraalkyldiamine; X = Cl or Br) by M(NS) 2 reagents (M = Co, Ni, Cu, Zn; NS is a monoanionic S-methylhydrazinecarbodithioate Schiff base ligand) depend on L, X, M and NS and the aprotic solvent. The kinetic data are compared with those for monotransmetalation of copper(II) complexes (μ 4-O)N 4Cu 4X 6 by M(NS) 2. Different kinetic behavior is particularly marked for cobalt(II) reactants. Unexpectedly high rates of reactions with Cu(NS) 2 are attributed to electron transfer. The results provide a basis for discussion of transmetalation specificity. 相似文献
10.
Synthesis of complexes cis,cis-W VOXL (X=Cl, NCS), cis,trans-W VOXL (X=Cl, OPh, SPh) and cis,trans-W VIE 2L (E 2=O 2, OS, S 2) of the title ligand LH 2 are reported. cis,cis-W VOCIL crystallises in space group P2 1/c with a=13.6541(9) Å, b=7.1555(11) Å, c=18.198(2) Å, β=95.294(6)°, V=1770.4(3) Å 3 and Z=4 while the cis,trans isomer crystallises in space group P2 1/n with a=10.361(3) Å, b=14.141(4) Å, c=12.213(5) Å, β=102.56(3)°, V=1747(2) Å 3 and Z=4. cis,trans-W VIS 2L crystallises in space group P2 1/n with a=10.645(2) Å, b=13.929(2) Å, c=12.189(2) Å, β=103.14(2)°, V=1760(1) Å 3 and Z=4. A short CH 3···Cl distance of 3.067(7) Å and an acute OWCl angle of 94.1(2)° are seen in cis,cis-W VOClL, which converts to the cis,trans form on heating in MeCN. The latter isomer features a CH 3···Cl distance of 3.38(2) Å and an OWCl angle of 105.1(8)°. Electrochemical and EPR data are reported. In particular, cis,trans-W VIE 2L may be reduced to [W VE 2L] –. EPR properties of these anions and those of complexes W VOXL are discussed in the context of W V centres in tungsten enzymes. 相似文献
11.
Two ternary Zn(II) complexes, with 1,10-phenanthroline (phen) as the main ligand and a carboxylate-containing ligand [dipicolinate (dipico) or L-threoninate (L-Thr)] as the subsidiary ligand, were prepared and characterized by elemental analysis, Fourier transform IR, UV, and fluorescence spectroscopy, X-ray diffraction, molar conductivity, and electrospray ionization mass spectrometry. X-ray structure analysis shows that both [Zn(phen)(dipico)(H(2)O)]·H(2)O (1) and [Zn(phen)(L-Thr)(H(2)O)Cl]·2H(2)O (2) have octahedral geometry about the Zn(II) atom. Both complexes can inhibit topoisomerase I, and have better anticancer activity than cisplatin against nasopharyngeal cancer cell lines, HK1 and HONE-1, with concentrations causing 50?% inhibition of cell proliferation (IC(50)) in the low micromolar range. Complex 2 has the highest therapeutic index for HK1. Both Zn(II) complexes can induce cell death by apoptosis. Changing the subsidiary ligand in the Zn(II) complexes affects the UV-fluorescence spectral properties of the coordinated phen ligand, the binding affinity for some DNA sequences, nucleobase sequence-selective binding, the phase at which cell cycle progression was arrested for treated cancer cells, and their therapeutic index. 相似文献
14.
The observation of 2h
J
iso(N, N) coupling has prompted considerable interest in this phenomenon from experimentalists and theoreticians due to the potential these couplings hold for the determination of secondary and tertiary structure in biologically important molecules. Here, we present an ab initio (MCSCF) study of the complete 2h
J(N, N) tensor for a model methyleneimine dimer system as a function of ( i) the N-N separation, r
NN, and ( ii) the hydrogen bond angle, . This simple system models the 2h
J(N, N) tensor of nucleic acid base pairs. Results indicate that although the Fermi-contact mechanism dominates 2h
J
iso(N, N), the coupling tensor is anisotropic due to contributions from the Fermi-contact spin-dipolar cross term. The variation in 2h
J
iso(N, N) as a function of r
NN is fit to an exponential decay. The influence of on the coupling constant is less pronounced but must be considered if experimental coupling constants are to be used for quantitative structure determination. Our results for this simple model system demonstrate that 2h
J
iso(N, N) is a valuable probe of hydrogen bonding in nucleic acid base pairs. 相似文献
15.
The effect of microinjected calcium-loaded 1,2-bis(2-aminophenoxy) ethane-N,N,N,N-tetraacetic acid (CaBAPTA) on cell-to-cell diffusion of carboxyfluorescein (CF) was examined in staminal hairs of S. purpurea Boom. The CaBAPTA was microinjected into the cytoplasm of the staminal hairs either with CF or prior to a subsequent microinjection of CF. The cell-to-cell diffusion of CF along the hair was monitored using enhanced-fluorescence video microscopy. Cytoplasmic streaming stopped in cells treated with CaBAPTA, indicating that intracellular Ca 2+ had increased. Cell-to-cell diffusion of CF was blocked in cells treated with Ca-BAPTA. An inhibition of cytoplasmic streaming and cell-to-cell diffusion was observed in the cells adjoining the CaBAPTA-microinjected cell, indicating that the Ca-BAPTA appeared to pass through plasmodesmata. While cytoplasmic streaming resumed 5–10 min after CaBAPTA treatment, cell-to-cell diffusion did not resume until 30–120 min later. These data support an involvement of calcium in the regulation of cell-to-cell communication in plants.Abbreviations BAPTA
1,2-bis(2-aminophenoxy)ethane-N,N,N, N-tetraacetic acid
- CF
carboxyfluorescein
This work was supported by Professional Staff Congress-City University (PSC-CUNY) of New York grant No. 667180 and U.S. Department of Agriculture grant No. 87-CRCR-1-244. 相似文献
16.
We report the assignment of the 110 amino acid second calponin homology domain of human α-actinin-4. The two calponin homology
domains of α-actinin combine to regulate F-actin binding. 相似文献
17.
Dimeric copper(I) complexes L 2Cu 2X 2 react with 1 and 2 mol of M(NS) 2 reagents in aprotic solvents to give quantitative yields of products LMX 2 and (NS)M(X,X)M(NS), respectively. Here, L = N,N,N′N′-tetraethylethylenediamine, X = Cl or Br, M = Co, Ni, Cu and Ns = S-methylisopropylidenehydrazinecarbodithioate. Dimers (NS)Cu(X,X)Cu(NS) are oxidatively unstable. LCoCl 2 crystallizes in the monoclinic space group P2 1/ c (C 2h5): a = 7.345(1), b = 11.801(1), c = 17.478(2) Å, β = 104.98(1)°, Z = 4. The electronic spectra of LMX 2 and (NS)M(X,X)M(NS) complexes are discussed. 相似文献
18.
Summary Dicyclohexylcarbodiimide (DCCD) and the 5-ethylisopropyl-6-bromo-derivative of amiloride (Br-EIPA) have been used as affinity and photoaffinity labels of the Na +/H + exchanger in rat renal brush-border membranes. Intravesicular acidification by the Na –/H + exchanger was irreversibly inhibited after incubation of vesicles for 30 min with DCCD. The substrate of the antiporter, Na +, and the competitive inhibitor, amiloride, protected from irreversible inhibition. The Na +-dependent transport systems for sulfate, dicarboxylates, and neutral, acidic, and basic amino acids were inhibited by DCCD, but not protected by amiloride. An irreversible inhibition of Na +/H + exchange was also observed when brush-border membrane vesicles were irradiated in the presence of Br-EIPA. Na + and Li + protected. [ 14C]-DCCD was mostly incorporated into three brush-border membrane polypeptides with apparent molecular weights of 88,000, 65,000 and 51,000. Na + did not protect but rather enhanced labeling. In contrast, amiloride effectively decreased the labeling of the 65,000 molecular weight polypeptide. In basolateral membrane vesicles one band was highly labeled by [ 14C]-DCCD that was identified as the -subunit of the Na +, K +-ATPase. [ 14C]-Br-EIPA was mainly incorporated into a brushborder membrane polypeptide with apparent molecular weight of 65,000. Na + decreased the labeling of this protein. Similar to the Na +/H + exchanger this Na +-protectable band was absent in basolateral membrane vesicles. We conclude that a membrane protein with an apparent molecular weight of 65,000 is involved in rat renal Na +/H + exchange. 相似文献
19.
By seeking new stable boron-containing nucleoside derivatives, potential BNCT boron delivery agents, a novel synthetic approach was tested, aimed at a boron attachment via a single bond to an aliphatic carbon of sp 3 hybridization. The latter allowed successful modification of deoxycytidine in the reaction with 2-(iodomethyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane of the deoxynucleoside amino group. For new compounds, detailed NMR, LDI HRMS (Laser Desorption/Ionization High-Resolution Mass Spectrometry) analyses along with in vivo phosphorylation studies, toxicity assays and DFT modelling are presented. 相似文献
20.
Iron chlorosis is commonly corrected by the application of EDDHA chelates, whose industrial synthesis produces o,oEDDHA together with a mixture of regioisomers and other unknown by-products. HJB, an o,oEDDHA analogous, is a new chelating agent with a purer synthesis pathway than EDDHA. The HJB/Fe 3+ stability constant is intermediate between the racemic and meso o,oEDDHA/Fe 3+ stereoisomers. This work studied the efficacy of HJB as a Fe source in plant nutrition. No significant differences between o,oEDDHA/Fe 3+, HJB/Fe 3+ and HBED/Fe 3+ were observed when they are used as substrates of the iron-chelate reductase of mild chlorotic cucumber plants. Chelates prepared with the stable isotope 57Fe were used in both soil and hydroponic experiments. In the hydroponic experiment, nutrient solutions with low doses of chelates were renewed weekly. Soybean plants treated with o,oEDDHA/ 57Fe 3+ recorded the highest results in biomass, SPAD index and Fe nutrition. In the soil experiment, chelates were added once at a rate of 2.5 mg Fe per kg of a calcareous soil. Soybean plants treated with HJB/ 57Fe 3+ recorded a higher biomass and SPAD index in young leaves than the plants treated with o,oEDDHA/ 57Fe 3+; however, 57Fe and total Fe concentrations in leaves were lower. The results of both pot experiments are associated with a faster ability by o,oEDDHA to provide Fe to the plants and with a more continuous supply of Fe from HJB/Fe 3+. HJB/ 57Fe 3+ effectively alleviated the Fe-deficiency chlorosis of soybean with a longer lasting effect than o,oEDDHA/ 57Fe 3+. 相似文献
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