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51.
Blindauer CA Polfer NC Keiper SE Harrison MD Robinson NJ Langridge-Smith PR Sadler PJ 《Journal of the American Chemical Society》2003,125(11):3226-3227
Using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry, we show that one Zn2+ ion in the Zn4 cluster of cyanobacterial metallothionein is inert to exchange with 67Zn2+. We suggest that this is zinc in site A, which together with the surrounding alpha and beta secondary structure forms a zinc-finger fold. 相似文献
52.
A microfluidic approach for rapid bioluminescent real-time detection of single nucleotide polymorphism (SNP) is presented. The method is based on single-step primer extension using pyrosequencing chemistry to monitor nucleotide incorporations in real-time. The method takes advantage of the fact that the reaction kinetics differ between matched and mismatched primer-template configurations. We show here that monitoring the initial reaction in real time accurately scores SNPs by comparing the initial reaction kinetics between matched and mismatched configurations. Thus, no additional treatment is required to improve the sequence specificity of the extension, which has been the case for many allele-specific extension assays. The microfluidic approach was evaluated using four SNPs. Three of the SNPs included primer-template configurations that have been previously reported to be difficult to resolve by allele-specific primer extension. All SNPs investigated were successfully scored. Using the microfluidic device, the volume for the bioluminescent assay was reduced dramatically, thus offering a cost-effective and fast SNP analysis method. 相似文献
53.
Incorporation of metalated nucleosides into DNA through covalent modification is crucial to measurement of thermal electron-transfer rates and the dependence of these rates with structure, distance, and position. Here, we report the first synthesis of an electron donor-acceptor pair of 5' metallonucleosides and their subsequent incorporation into oligonucleotides using solid-phase DNA synthesis techniques. Large-scale syntheses of metal-containing oligonucleotides are achieved using 5' modified phosporamidites containing [Ru(acac)(2)(IMPy)](2+) (acac is acetylacetonato; IMPy is 2'-iminomethylpyridyl-2'-deoxyuridine) (3) and [Ru(bpy)(2)(IMPy)](2+) (bpy is 2,2'-bipyridine; IMPy is 2'-iminomethylpyridyl-2'-deoxyuridine) (4). Duplexes formed with the metal-containing oligonucleotides exhibit thermal stability comparable to the corresponding unmetalated duplexes (T(m) of modified duplex = 49 degrees C vs T(m) of unmodified duplex = 47 degrees C). Electrochemical (3, E(1/2) = -0.04 V vs NHE; 4, E(1/2) = 1.12 V vs NHE), absorption (3, lambda(max) = 568, 369 nm; 4, lambda(max) = 480 nm), and emission (4, lambda(max) = 720 nm, tau = 55 ns, Phi = 1.2 x 10(-)(4)) data for the ruthenium-modified nucleosides and oligonucleotides indicate that incorporation into an oligonucleotide does not perturb the electronic properties of the ruthenium complex or the DNA significantly. In addition, the absence of any change in the emission properties upon metalated duplex formation suggests that the [Ru(bpy)(2)(IMPy)](2+)[Ru(acac)(2)(IMPy)](2+) pair will provide a valuable probe for DNA-mediated electron-transfer studies. 相似文献
54.
Nigel T. Lucas Marie P. Cifuentes Lam T. Nguyen Mark G. Humphrey 《Journal of Cluster Science》2001,12(1):201-221
The new phosphines Ph2PC6H4-4-CCR [R=SiMe3 (1), H (2)] have been used to prepare Ru3(CO)9(Ph2PC6H4-4-CCSiMe3)3 (4) and Ru(CCC6H4-4-PPh2)(PPh3)2(-C5H5) (3), respectively, the latter with a pendent phosphine. Reaction of 4 with carbonate or fluoride affords Ru3(CO)9(Ph2PC6H4-4-CCH)3 (5) with pendent terminal alkynyl groups, the identity of which was confirmed by a structural study. Reaction of 5 with [Ru(NCMe)(PPh3)2(-C5H5)]PF6 or reaction of Ru3(CO)12 with 3 gives Ru3(CO)9{(Ph2PC6H4-4-CC)Ru(PPh3)2(-C5H5)}3 (6). Complexes 3–6 have been studied by cyclic voltammetry. Proceeding from Ru3(CO)12 to 4 or 5 shifts the cluster-centred reduction to more negative potential and affords facile cluster-centred oxidation. Proceeding from 4/5 and 3 to 6 results in similarly-located cluster-centred reduction and peripheral ruthenium-centred oxidation, but results in a lack of observable cluster-centred oxidation. Crystal data for 5·C6H14: space group P¯1, a=12.760(1) Å, b=17.077(1) Å, c=17.924(2) Å, =108.656(5)°, =96.344(5)°, =93.523(5)°, V=3658.4(6) Å3, Z=2, R=0.078, Rw=0.105 for 5008 reflections [I>2.00(I)]. 相似文献
55.
Alistair J Usher Nigel T Lucas Simon Petrie Mark G Humphrey Anthony C Willis 《Journal of organometallic chemistry》2004,689(1):50-57
Reaction of WH(CO)3(η-C5Me5) with IrCl(CO)2(4-H2NC6H4Me) affords WIr3(μ-CO)3(CO)8(η-C5Me5) in low yield. A structural study reveals a WIr2-centred plane of bridging carbonyls, in contrast to the crystal structure of WIr3(CO)11(η-C5H5) (all-terminal carbonyl distribution). DFT calculations reveal an increasing proclivity to adopt an all-terminal CO disposition for clusters MIr3(CO)11(η-C5H5) in the gas phase on proceeding from M=Cr to Mo and then W, consistent with structural studies in the solid state for which the tungsten-containing cluster is the only all-terminal example. Increasing electron donation from the ligands in the tungsten system (either from phosphine substitution or cyclopentadienyl permethylation) suffices to impose a plane of bridging carbonyls in the ground state structure. 13C NMR fluxionality studies reveal that CO exchange mechanism(s) for WIr3(CO)11(η-C5H5) and the related tetrahedral cluster W2Ir2(CO)10(η-C5H5)2 are very fast and involve all carbonyls on the clusters. DFT calculations on MIr3(CO)11(η-C5H5) (M=Cr, Mo) substantiate a ‘merry-go-round’ mechanism for carbonyl scrambling in these systems, a result which is consistent with the scrambling behaviour seen in the NMR fluxionality studies on the W-containing congener. 相似文献
56.
Gregory N. Coppin Andrew Hudson Richard A. Jackson Nigel P.C. Simmons 《Journal of organometallic chemistry》1977,131(3):371-375
The formation of the compound RSnX(acac)2 (acac = 2,4-pentanedionato) by reaction of bis(2,4-pentanedionato)tin(II) on a halide RX with R = CH3, C2H5, C4H9, C6H5, CH2I, (C6H5)3SnCH2, (C2H5)3SnCH2 and X = I, Br has been studied by polarography. At 25°C, it is in fact an equilibrium whose constant has been measured. The intermediate formation of the ion-pair [RSn(acac)2+X?] has allowed us to explain the experimental results. 相似文献
57.
Boyd DR Sharma ND Bowers NI Dalton H Garrett MD Harrison JS Sheldrake GN 《Organic & biomolecular chemistry》2006,4(17):3343-3349
Biotransformations of a series of ortho-, meta- and para-substituted ethylbenzene and propylbenzene substrates have been carried out, using Pseudomonas putida UV4, a source of toluene dioxygenase (TDO). The ortho- and para-substituted alkylbenzene substrates yielded, exclusively, the corresponding enantiopure cis-dihydrodiols of the same absolute configuration. However, the meta isomers, generally, gave benzylic alcohol bioproducts, in addition to the cis-dihydrodiols (the meta effect). The benzylic alcohols were of identical (R) absolute configuration but enantiomeric excess values were variable. The similar (2R) absolute configurations of the cis-dihydrodiols are consistent with both the ethyl and propyl groups having dominant stereodirecting effects over the other substituents. The model used earlier, to predict the regio- and stereo-chemistry of cis-dihydrodiol bioproducts derived from substituted benzene substrates has been refined, to take account of non-symmetric substituents like ethyl or propyl groups. The formation of benzylic hydroxylation products, from meta-substituted benzene substrates, without further cis-dihydroxylation to yield triols provides a further example of the meta effect during toluene dioxygenase-catalysed oxidations. 相似文献
58.
59.
A generic method for the synthesis of metal-7,7,8,8-tetracyanoquinodimethane (TCNQ) charge-transfer complexes on both conducting and nonconducting substrates is achieved by photoexcitation of TCNQ in acetonitrile in the presence of a sacrificial electron donor and the relevant metal cation. The photochemical reaction leads to reduction of TCNQ to the TCNQ(-) monoanion. In the presence of M(x+)(MeCN), reaction with TCNQ(-)(MeCN) leads to deposition of M(x+)[TCNQ]x crystals onto a solid substrate with morphologies that are dependent on the metal cation. Thus, CuTCNQ phase I photocrystallizes as uniform microrods, KTCNQ as microrods with a random size distribution, AgTCNQ as very long nanowires up to 30 mum in length and with diameters of less than 180 nm, and Co[TCNQ](2)(H(2)O)(2) as nanorods and wires. The described charge-transfer complexes have been characterized by optical and scanning electron microscopy and IR and Raman spectroscopy. The CuTCNQ and AgTCNQ complexes are of particular interest for use in memory storage and switching devices. In principle, this simple technique can be employed to generate all classes of metal-TCNQ complexes and opens up the possibility to pattern them in a controlled manner on any type of substrate. 相似文献
60.
Prasain JK Patel R Kirk M Wilson L Botting N Darley-Usmar VM Barnes S 《Journal of mass spectrometry : JMS》2003,38(7):764-771
Electrospray ionization combined with tandem mass spectrometry was applied to a study of some representative chlorinated and nitrated isoflavones-potential metabolites of isoflavones in inflammatory cells. Upon collision-induced dissociation of deprotonated [M - H](-) ions of these compounds, a number of structurally characteristic product ions were produced. The product ion analysis of 3'- and 8-chlorodaidzein in the tandom mass spectra led to ready differentiation of these isomers. 3-Nitro derivatives of both genistein and daidzein have product ions due to the losses of HNO(2) and two OH groups. Chlorinated derivatives of isoflavones were detected in cell-based experiments and their structures were proposed by comparing the tandem mass spectra of their product ions with those of standards. This work provides a suitable analytical basis to aid the characterization of chlorinated and nitrated metabolites in studies in vivo and in vitro. 相似文献