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Benjamin Large Natalia G. Baranska Rosalind L. Booth Keith S. Wilson Anne-Kathrin Duhme-Klair 《Current Opinion in Green and Sustainable Chemistry》2021
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Johannes Kretsch Anne-Kathrin Kreyenschmidt Timo Schillmöller Dr. Märt Lõkov Dr. Regine Herbst-Irmer Prof. Dr. Ivo Leito Prof. Dr. Dietmar Stalke 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(38):9858-9865
A novel sterically demanding bis(4-benzhydryl-benzoxazol-2-yl)methane ligand 6 (4−BzhH2BoxCH2) was gained in a straightforward six-step synthesis. Starting from this ligand monomeric [M(4-BzhH2BoxCH)] (M=Na ( 7 ), K ( 81 )) and dimeric [{M(4-BzhH2BoxCH)}2] (M=K ( 82 ), Rb ( 9 ), Cs ( 10 )) alkali metal complexes were synthesised by deprotonation. Abstraction of the potassium ion of 8 by reaction with 18-crown-6 resulted in the solvent separated ion pair [{(THF)2K@(18-crown-6)}{bis(4-benzhydryl-benzoxazol-2-yl)methanide}] ( 11 ), including the energetically favoured monoanionic (E,E)-(4-BzhH2BoxCH) ligand. Further reaction of 4−BzhH2BoxCH2 with three equivalents KH and two equivalents 18-crown-6 yielded polymeric [{(THF)2K@(18-crown-6)}{K@(18-crown-6)K(4-BzhBoxCH)}]n (n→∞) ( 12 ) containing a trianionic ligand. The neutral ligand and herein reported alkali complexes were characterised by single X-ray analyses identifying the latter as a promising precursor for low-valent main group complexes. 相似文献
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Peter?Schwenkreis Andrea?Scherens Anne-Kathrin?R?nnau Oliver?H?ffken Martin?Tegenthoff Christoph?Maier 《BMC neuroscience》2010,11(1):73
Background
The aim of this study was to examine the relationship between chronic neuropathic pain after incomplete peripheral nerve lesion, chronic nociceptive pain due to osteoarthritis, and the excitability of the motor cortex assessed by transcranial magnetic stimulation (TMS). Hence in 26 patients with neuropathic pain resulting from an isolated incomplete lesion of the median or ulnar nerve (neuralgia), 20 patients with painful osteoarthritis of the hand, and 14 healthy control subjects, the excitability of the motor cortex was tested using paired-pulse TMS to assess intracortical inhibition and facilitation. These excitability parameters were compared between groups, and the relationship between excitability parameters and clinical parameters was examined. 相似文献4.
Kampschulte L Lackinger M Maier AK Kishore RS Griessl S Schmittel M Heckl WM 《The journal of physical chemistry. B》2006,110(22):10829-10836
This work presents a scanning tunneling microscopy (STM) based study of benzenetribenzoic acid (BTB) monolayer structures at the liquid-solid interface. On graphite(0001) the tailored molecules self-assemble into 2D supramolecular host systems, suitable for the incorporation of other nanoscopic objects. Two crystallographically different BTB structures were found-both hydrogen bonded networks. A specific structure was deliberately selected by solvent identity. One of the BTB polymorphs is a 6-fold chicken-wire structure with circular, approximately 2.8 nm wide cavities. The other structure exhibits an oblique unit cell and a different hydrogen bonding pattern. The large cavity size of the chicken-wire structure was made possible through comparatively strong 2-fold hydrogen bonds between carboxylic groups. In addition, the low conformational flexibility of BTB was supportive to combat the tendency for dense packing. 相似文献
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Bohne C Faulhaber K Giese B Häfner A Hofmann A Ihmels H Köhler AK Perä S Schneider F Sheepwash MA 《Journal of the American Chemical Society》2005,127(1):76-85
Mechanistic investigations of the photoinduced DNA damage by acridizinium salts (4a-azonia-anthracene derivatives) are presented. Irradiation of 9-bromoacridizinium in the presence of defined double- and single-stranded DNA oligomers under aerobic conditions leads to both frank strand breaks and alkali-labile sites as determined by polyacrylamide gel electrophoresis (PAGE). The extent of the DNA damage increases significantly in D(2)O and occurs selectively at guanosine residues. These observations reveal the formation of singlet oxygen ((1)O(2)) as reactive species, which oxidizes the DNA bases, above all the guanine bases. Further evidence for (1)O(2) formation was obtained from laser-flash spectroscopic investigations, which show intersystem crossing (S(1) to T(1)) of the excited states of the parent acridizinium and of the 9-bromo- and 9-amino-substituted derivatives. The resulting triplet state is efficiently quenched by oxygen (k(q) > 10(9) s(-)(1)M(-)(1)) to yield (1)O(2). Under anaerobic conditions, no significant alkali-labile lesions are observed, but frank strand breaks are induced; however, to lesser extent than under aerobic conditions. The DNA damage is suppressed in the presence of a radical scavenger, namely t-BuOH, and hydroxyl radicals are shown to be the reactive intermediates by trapping experiments with terephthalic acid. Moreover, the intercalated acridizinium molecules are not involved in the DNA damage reactions. The intercalated acridizinium salt leads to a primary PET reaction with the DNA bases; however, a fast BET transfer is proposed that regains the dye and the DNA, so that the excited intercalated dye does not contribute significantly to the overall DNA damage. 相似文献
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Christopher W. Heppel Anne-Kathrin Heling Elmar Richter 《Analytical and bioanalytical chemistry》2009,393(5):1525-1530
4-Hydroxy-1-(3-pyridyl)-1-butanone (HPB)-releasing DNA adducts are formed by metabolic activation of the tobacco-specific
nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N′-nitrosonornicotine (NNN). NNK and NNN are considered carcinogenic to humans by the International Agency for Research on
Cancer. Existing analytical methods for determination of HPB-releasing DNA adducts require 0.3–2.0 g of human target tissues
such as lung and esophagus. For adduct determination in milligram amounts of biopsy samples, an ultrasensitive and specific
method is presented using capillary gas chromatography coupled to a high-resolution mass spectrometer operated in the negative
chemical ionization mode (GC-NCI-HRMS). The method has a limit of detection of 4.6 fmol HPB, a limit of quantification of
14.9 fmol HBP and a recovery of 45 ± 15%. Intra- and inter-day imprecision for N = 6 samples were calculated with coefficients of variation of <3.1%. Method applicability was evaluated with biopsies of
esophageal mucosa (N = 14) yielding 5.6 ± 1.9 mg tissue and a mean adduct level of 6.13 ± 9.35 pmol HPB/mg DNA. 相似文献
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Anne-Kathrin Duhme 《无机化学与普通化学杂志》1998,624(11):1922-1926
Reaction of the dinucleating ligand N,N'-bis(2,3-dihydroxybenzoyl)-α, α-diaminopropane H4-1 with molybdate results in the formation of the meso-helicate type molecular rectangle Δ, Λ-[{MoO2( 1 )}2]4– as confirmed by NMR-spectroscopy and X-ray crystallography. Thereby the cis-dioxo Mo(VI) moieties act as shape defining corner units. The potassium salt of the complex crystallised in the centrosymmetric space group P1¯ with unit cell parameters a = 12.370(2), b = 13.900(3), c = 14.340(3) Å; α = 116.34(3), β = 99.12(3), γ = 96.68(3)°; V = 2132.6(7) Å3; Z = 2. 相似文献
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Bunge A Kurz A Windeck AK Korte T Flasche W Liebscher J Herrmann A Huster D 《Langmuir : the ACS journal of surfaces and colloids》2007,23(8):4455-4464
For the development of surface functionalized bilayers, we have synthesized lipophilic oligonucleotides to combine the molecular recognition mechanism of nucleic acids and the self-assembly characteristics of lipids in planar membranes. A lipophilic oligonucleotide consisting of 21 thymidine units and two lipophilic nucleotides with an alpha-tocopherol moiety as a lipophilic anchor was synthesized using solid-phase methods with a phosphoramadite strategy. The interaction of the water soluble lipophilic oligonucleotide with vesicular lipid membranes and its capability to bind complementary DNA strands was studied using complementary methods such as NMR, EPR, DSC, fluorescence spectroscopy, and fluorescence microscopy. This oligonucleotide inserted stably into preformed membranes from the aqueous phase. Thereby, no significant perturbation of the lipid bilayer and its stability was observed. However, the non-lipidated end of the oligonucleotide is exposed to the aqueous environment, is relatively mobile, and is free to interact with complementary DNA strands. Binding of the complementary single-stranded DNA molecules is fast and accomplished by the formation of Watson-Crick base pairs, which was confirmed by 1H NMR chemical shift analysis and fluorescence resonance energy transfer. The molecular structure of the membrane bound DNA double helix is very similar to the free double-stranded DNA. Further, the membrane bound DNA double strands also undergo regular melting. Finally, in raft-like membrane mixtures, the lipophilic oligonucleotide was shown to preferentially sequester into liquid-disordered membrane domains. 相似文献
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Anne-Kathrin Hendrischk Julia Moldt Sebastian Walter Frühwirth Gabriele Klug 《Photochemistry and photobiology》2009,85(5):1254-1259
The facultatively phototrophic purple bacterium Rhodobacter sphaeroides 2.4.1 harbors a LOV (light, oxygen and voltage) domain protein, which shows a particular structure. LOV domains perceive blue light by a noncovalently bound flavin and transmit the signal to various coupled output domains. Proteins, that harbor a LOV core, function e.g. as phototropins or circadian clock regulators. Jα helices, which act as linker between the LOV core and the output domain, were shown to be involved in the light-dependent activation of the output domain. Like PpSB2 from Pseudomonas putida , the LOV domain protein of R. sphaeroides is not coupled to an effector domain and harbors an extended C-terminal α helix. We expressed the R. sphaeroides LOV domain recombinantly in Escherichia coli . The protein binds an FMN as a cofactor and shows a photocycle typical for LOV domain containing proteins. In R. sphaeroides , we detected the protein as well in the cytoplasm as in the membrane fraction, which was not reported for other bacterial LOV domain proteins. 相似文献
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