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51.
Martin JN Muñoz EM Schwergold C Souard F Asensio JL Jiménez-Barbero J Cañada J Vicent C 《Journal of the American Chemical Society》2005,127(26):9518-9533
Sugar-oligoamides have been designed and synthesized as structurally simple carbohydrate-based ligands to study carbohydrate-DNA interactions. The general design of the ligands 1-3 has been done as to favor the bound conformation of Distamycin-type gamma-linked covalent dimers which is a hairpin conformation. Indeed, NMR analysis of the sugar-oligoamides in the free state has indicated the presence of a percentage of a hairpin conformation in aqueous solution. The DNA binding activity of compounds 1-3 was confirmed by calf thymus DNA (ct-DNA) NMR titration. Interestingly, the binding of the different sugar-oligoamides seems to be modulated by the sugar configuration. Semiquantitative structural information about the DNA ligand complexes has been derived from NMR data. A competition experiment with Netropsin suggested that the sugar-oligoamide 3 bind to DNA in the minor groove. The NMR titrations of 1-3 with poly(dA-dT) and poly(dG-dC) suggested preferential binding to the ATAT sequence. TR-NOE NMR experiments for the sugar-oligoamide 3-ct-DNA complex both in D(2)O and H(2)O have confirmed the complex formation and given information on the conformation of the ligand in the bound state. The data confirmed that the sugar-oligoamide ligand is a hairpin in the bound state. Even more relevant to our goal, structural information on the conformation around the N-glycosidic linkage has been accessed. Thus, the sugar asymmetric centers pointing to the NH-amide and N-methyl rims of the molecule have been characterized. 相似文献
52.
Summary Two high-performance liquid chromatography (HPLC) techniques were developed for the determination of binding constants in
the interaction of serum albumin with L-tryptophan: internal calibration and external calibration. The results obtained were
compared with those obtained by the classical method of equilibrium dialysis and by gel filtration. While all the methods
are equally reliable, the internal and external calibration techniques seem to be superior in their simplicity, speed and
convenience. 相似文献
53.
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55.
Seggio A Lannou MI Chevallier F Nobuto D Uchiyama M Golhen S Roisnel T Mongin F 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(35):9982-9989
Metalation of N-phenylpyrrole by using an in situ mixture of ZnCl(2)TMEDA (0.5 equiv; TMEDA=N,N,N',N'-tetramethylethylenediamine) and LiTMP (1.5 equiv; TMP=2,2,6,6-tetramethylpiperidino) was optimized. The reaction carried out at room temperature in THF resulted in incomplete metalation (56 % conversion) and selectivity (mixture of 2-iodo and 2,2'-diiodo derivatives in an 86:14 ratio after trapping with iodine). By using diethyl ether (DEE), toluene, or hexane instead of THF, low conversions of 17, 38, or 23 % were observed, respectively, but the formation of the diiodide was avoided. When hexane was used as solvent, strong lithium-complexing ligands such as [12]crown-4 and N,N'-dimethylpropylideneurea (DMPU) inhibited the reaction whereas more (hemi)labile ligands (TMEDA>THF approximately DME) favored it. This result shows that a temporary accessibility of lithium to interact with the rest of the base and/or the substrate is a prerequisite for an efficient metalation. A 75 % yield of 2-iodo-N-phenylpyrrole was obtained after reaction with the base in the presence of five equivalents of TMEDA for two hours at room temperature, and subsequent trapping with iodine. We were able to successfully replace the spare TMP with a less expensive butyl group. 相似文献
56.
Florence Babonneau Christine Toutou Stéphanie Gavériaux 《Journal of Sol-Gel Science and Technology》1997,8(1-3):553-556
17O NMR experiments using enriched water were performed to followthe hydrolysis-condensation process of dimethyldiethoxysilanetetraethoxysilane and a 1/1 mixture of dimethyldiethoxysilane andtetraethoxysilane (H2O/OEt = 0.5; pH = 2). The spectrarecorded over several hours time period were simulated to followquantitatively the variations of residual water, hydroxyl groups(Si–17
H) and oxo bridges (Si–17
–Si). Presence of a resonance signal due oxo bridges between di- andtetrafunctional Si units clearly demonstrates that co-condensationreactions occur to a large extent between the two alkoxides, and that thesebonds are stable during the aging period. 相似文献
57.
Viet Hung Dao Isabelle Ourliac-Garnier Cdric Log Florence O. McCarthy Stphane Bach Teresinha Gonalves da Silva Caroline Denevault-Sabourin Jrme Thifaine Blandine Baratte Thomas Robert Fabrice Gouilleux Marie Brachet-Botineau Marc-Antoine Bazin Pascal Marchand 《Molecules (Basel, Switzerland)》2021,26(21)
Pim kinases (proviral integration site for Moloney murine leukemia virus kinases) are overexpressed in various types of hematological malignancies and solid carcinomas, and promote cell proliferation and survival. Thus, Pim kinases are validated as targets for antitumor therapy. In this context, our combined efforts in natural product-inspired library generation and screening furnished very promising dibenzo[b,d]furan derivatives derived from cercosporamide. Among them, lead compound 44 was highlighted as a potent Pim-1/2 kinases inhibitor with an additional nanomolar IC50 value against CLK1 (cdc2-like kinases 1) and displayed a low micromolar anticancer potency towards the MV4-11 (AML) cell line, expressing high endogenous levels of Pim-1/2 kinases. The design, synthesis, structure–activity relationship, and docking studies are reported herein and supported by enzyme, cellular assays, and Galleria mellonella larvae testing for acute toxicity. 相似文献
58.
Dave Anderson Mathieu Florence Zinovy Reichstein 《Comptes Rendus Mathematique》2013,351(23-24):871-875
Let G be a split simple group of type over a field k, and let be its Lie algebra. Answering a question of J.-L. Colliot-Thélène, B. Kunyavski?, V.L. Popov, and Z. Reichstein, we show that the function field is generated by algebraically independent elements over the field of adjoint invariants . 相似文献
59.
M. Florence 《Transformation Groups》2006,11(2):161-176
Let k be a perfect field and G an algebraic group defined over k. Let X be a homogeneous space of G. We show the following:
if there exists a k-variety which is birational to X and which has a smooth k-rational point, then X also has a k-rational
point (Theorem 5.7). 相似文献
60.
In this paper, we study the central limit theorem and its weak invariance principle for sums of a stationary sequence of random
variables, via a martingale decomposition. Our conditions involve the conditional expectation of sums of random variables
with respect to the distant past. The results contribute to the clarification of the central limit question for stationary
sequences.
Magda Peligrad is supported in part by a Charles Phelps Taft research support grant at the Univeristy of Cincinnati and the
NSA grant H98230-05-1-0066. 相似文献