离子交换色谱法研究蛋白质与RNA的结合特异性

RNA是以磷酸二酯键相连的核苷酸组成的聚阴离子,而蛋白质在PH小于它的等电点的缓冲溶液中带有正电性.因此,它们在离子交换色谱分子时能出现在差异很大的洗脱组分中.据此.我们设计了用离子交换色谱法研究蛋白质与RNA的结合特异性方法,用以研究位于T细胞核内的具有RNA结合活性的蛋白质人环素33(hCyP33)与不同RNA的结合特性.结果表明,人亲环素33只有ply(A)尾序列结构的mRNA,即poly(A)^ RNA发生特异性结合.     

Rational Design,Synthesis and Evaluation of Oxazolo[4,5-c]-quinolinone Analogs as Novel Interleukin-33 Inhibitors

Interleukin-33 (IL-33) is an epithelial-derived cytokine that plays an important role in immune-mediated diseases such as asthma, atopic dermatitis, and rheumatoid arthritis. Although IL-33 is considered a potential target for the treatment of allergy-related diseases, no small molecule that inhibits IL-33 has been reported. Based on the structure-activity relationship and in vitro 2D NMR studies employing ¹⁵N-labeled IL-33, we identified that the oxazolo[4,5-c]-quinolinone analog 7 c binds to the interface region of IL-33 and IL-33 receptor (ST2), an orphan receptor of the IL-1 receptor family. Compound 7 c effectively inhibited the production of IL-6 in human mast cells in a dose-dependent manner. Compound 7 c is the first low molecular weight IL-33 inhibitor and may be used as a prototype molecule for structural optimization and investigation of the IL-33/ST2 signaling pathway.     

Photosensitivity and photochemical reactions of poly(vinyl p-azidocinnamate)

The spectral sensitivity of poly(vinyl p-azidocinnamate)(PVACi) was discussed by comparison with poly(vinyl cinnamate)(PVCi) and poly(vinyl p-azidobenzoate). The photochemical reaction of PVACi was investigated with respect to the reactivity of two functional groups, namely, azido and cinnamoyl groups. It was found that cinnamoyl groups dimerized like PVCi and azido groups did not add to double bonds appreciably. The quantum yield of photolysis of azido groups was two times that of dimerization of cinnamoyl groups. A marked wavelength dependence of π–π^* and n–π^* absorption was observed in both the reactions of azido and cinnamoyl groups.     

Increased Nitrogenase Activity in Solar-Driven Biohybrids Containing Non-photosynthetic Bacteria and Conducting Polymers

A conductive polymer-based photosynthetic biohybrid is constructed to enhance biological nitrogen fixation by increasing nitrogenase activity in the non-photosynthetic bacterium Azotobacter Chroococcum (A. Chroococcum). The light-harvesting cationic poly(fluorene-alt-phenylene) (PFP) electrostatically binds to the surface of the bacteria and possesses satisfactory conductivity to facilitate electron transfer to the bacterium, promoting the nitrogen fixation pathway through redox proteins on the surface of the bacteria when under illumination. Therefore, the nitrogenase activity, hydrogen, NH₄⁺-N and L-amino acids production are increased by 260 %, 37 %, 44 %, and 47 %, respectively. The expression levels of nifD and nifK encoding molybdenum-iron (MoFe) protein and relevant nitrogen-fixing proteins are up-regulated. These photoactive conductive polymer-bacteria biohybrids provide a new method for improving the biological nitrogen fixation capability of non-photosynthetic nitrogen-fixing bacteria.     

Synthesis and characterization of certain new poly(bisimide)s. I

Maleic and citraconic anhydrides were reacted with several diamines to obtain a novel class of high temperature resistant bisimides.^1–3 The bisimides were characterized by melting points, elemental analysis, UV–Vis, ¹H- and ¹³C-NMR, and mass spectral analysis. The bisimide monomers were then polymerized by the addition process. A poly(amidemaleimide) was also synthesized by reacting maleic anhydride with p-aminobenzhydrazide. The thermal stability of these highly crosslinked poly(bisimide)s were examined by TGA and DTA. A neat bisimide monomer obtained from 2,2′-bis[4(p-aminophenoxy)phenyl] propane with maleic anhydride namely, 2,2′-bis[4-(p-maleimidophenoxy)phenyl]propane was reacted with 2,2′-bis[4(p-aminophenoxy)phenyl]propane by the Michael reaction.⁴ A fiber glass cloth reinforced laminate was prepared from bismaleimide and amine mixture and the mechanical properties of the test laminate evaluated.     

分子信标研究5-氟尿嘧啶对鼻咽癌HNE1细胞p33ING1基因转录水平的影响

p33ING1作为一种重要的抑癌基因，在乳腺癌及胃癌等恶性肿瘤细胞中的mRNA表达水平显著低于癌旁正常组织细胞中的表达，并导致这些肿瘤细胞的侵袭转移能力增强，对化疗药物及r射线和紫外线处理的敏感性降低。     

A comprehensive in Silico analysis of the functional and structural impact of single nucleotide polymorphisms (SNPs) in the human IL-33 gene

Interleukin 33 (IL-33) is the latest member of the IL-1 cytokine family, which plays both pro - and anti-inflammatory functions. Numerous Single-nucleotide polymorphisms (SNPs) in the IL-33 gene have been recognized to be associated with a vast variety of inflammatory disorders. SNPs associated studies have become a crucial approach in uncovering the genetic background of human diseases. However, distinguishing the functional SNPs in a disease-related gene from a pool of both functional and neutral SNPs is a major challenge and needs multiple experiments of hundreds or thousands of SNPs in candidate genes. This study aimed to identify the possible deleterious SNPs in the IL-33 gene using bioinformatics predictive tools. The nonsynonymous SNPs (nsSNPs) were analyzed by SIFT, PolyPhen, PROVEAN, SNP&GO, MutPred, SNAP, PhD SNP, and I-Mutant tools. The Non-coding SNPs (ncSNPs) were also analyzed by SNPinfo and RegulomeDB tools. In conclusion, our in-silico analysis predicted 5 nsSNPs and 22 ncSNPs as potential candidates in the IL-33 gene for future genetic association studies.     

Comparative Study of Lead(II) Selective Poly(vinyl chloride) Membrane Electrodes Based on Podand Derivatives as Ionophores

The two podand chelates based on diethylsulfide, 1,5‐bis(2′‐hydroxy‐4′‐nitrophenoxy)‐3‐thiapentane (L₁) and 1,5‐bis(8′‐oxybenzopyridine)‐3‐thia pentane (L₂), have been synthesized and explored as neutral ionophores for preparing poly(vinyl chloride) based membrane electrodes selective to Pb²⁺. The addition of anionic additives and various plasticizers has been found to substantially improve the performance of the electrode. The best performance was obtained with the electrode No. 1 having a membrane of ionophore (L₁) with the composition PVC:o‐NPOE:ionophore (L₁):NaTFPB (%w/w) of 33 : 62 : 3 : 2. The electrode exhibits Nernstian response with a slope of 31.57±0.3 mV decade^?1 of activity in the concentration range from 2.0×10^?9 to 1.0×10^?1 M Pb²⁺, performs satisfactorily over a wide pH range (1.6–7.0), with a fast response time (5 s).     

Morphologies and enzymatic degradability of melt-crystallized poly(3-hydroxybutyric acid-Co-6-hydroxyhexanoic acid)

The films of poly[(R)-3-hydroxybutyric acid-co-10mol% 6-hydroxy-hexanoic acid] (P[(R)-3HB-co-6HH]) were prepared by melt-crystallized method at various crystallization temperatures. The morphologies and properties of melt-crystallized films were characterized by means of x-ray diffraction, differential scanning calorimetry, optical microscopy, and scanning electron microscopy. All of the melt-crystallized films showed the banded spherulite morphology. The enzymatic degradation of melt-crystallized films was carried out at 37 °C in an aqueous solution (pH 7.4) of PHB depolymerase from Alcaligenes faecalis. The rate of enzymatic erosion was strongly dependent on the crystallinity of films, and the highest rate was as large as 2.15 mg·h⁻¹·cm⁻². After enzymatic degradation, the banded morphology of P[(R)-3HB-co-6HH] spherulites was visible, suggesting that PHB depolymerase predominantly hydrolyzes polymer chains on the edges of crystalline lamellar stacks.     

Carbazole substituted N-acylated linear polyethylenimines (PEI). synthesis and characterization of poly[N-(9-carbazolyl)acetylethylenimine] and poly[N-(2-(9-carbazolyl))propanoylethylenimine]

The synthesis of carbazola substituted N-acylated polyethylenimines, namely, poly[N-(9-carbazolyl)acetylethylenimine] 20 and poly[N-(2-(9-carbazolyl))propanoylethylenimine] 21 by a grafting reaction onto PEI and isomerization polymerization of the carbazole substituted 2-oxazolines is reported. A complete acylation of amino groups in PEI by the 9-carbazolylacetyl groups was achieved by the p-nitrophenyl active ester method but PEI was only partially N-acylated by the 2-(9-carbazolyl)propanoyl groups under similar reaction conditions. The carbazole substituted 2-oxazolines, namely, 2-(9-carbazolyl)methyl-2-oxazoline 18 and (R,S)-2-[1-(9-carbazolyl)]ethyl-2-oxazoline 19 , were prepared by a base induced cyclization of ß-chloroamides. The ring-opening isomerization polymerization of 18 and 19 in the molten state with a cationic initiator (dimethyl sulfate, methyl triflate, or ethylene glycol ditosylate) gave 20 and 21. Gel permeation chromatography of 20 and 21 obtained with different monomerto-initiator ratios gave evidence of a chain transfer reaction with the monomer. The polymers were characterized by elemental analyses, IR, and ¹H-NMR spectroscopy.     

Identification of Flavin Mononucleotide as a Cell‐Active Artificial N6‐Methyladenosine RNA Demethylase

N⁶‐Methyladenosine (m⁶A) represents a common and highly dynamic modification in eukaryotic RNA that affects various cellular pathways. Natural dioxygenases such as FTO and ALKBH5 are enzymes that demethylate m⁶A residues in mRNA. Herein, the first identification of a small‐molecule modulator that functions as an artificial m⁶A demethylase is reported. Flavin mononucleotide (FMN), the metabolite produced by riboflavin kinase, mediates substantial photochemical demethylation of m⁶A residues of RNA in live cells. This study provides a new perspective to the understanding of demethylation of m⁶A residues in mRNA and sheds light on the development of powerful small molecules as RNA demethylases and new probes for use in RNA biology.     

Novel double hydrophilic block copolymers based on poly(p‐hydroxystyrene) derivatives and poly(ethylene oxide)

The synthesis of three series of double hydrophilic block copolymers (DHBCs), consisting of poly(ethylene oxide) as the neutral water soluble block and a second polyelectrolyte block of variable chemistry, is described. The synthetic scheme involves the anionic polymerization of poly(p‐tert‐butoxystyrene‐b‐ethylene oxide) (PtBOS‐PEO) amphiphilic block copolymer precursors followed by the acidic hydrolysis of the hydrophobic poly(p‐tert‐butoxystyrene) (PtBOS) block to an annealed anionic polyelectrolyte poly(p‐hydroxystyrene) (PHOS) block. The PHOS block was subsequently transformed into a high charge density annealed cationic polyelectrolyte namely poly[3,5‐bis(dimethylaminomethylene) hydroxystyrene] (NPHOS), via aminomethylation. Finally, the NPHOS block was transformed into a quenched polyelectrolyte, namely quaternized poly[3,5‐bis(dimethylaminomethylene) hydroxystyrene] (QNPHOS) block by reaction with CH₃I. The solution properties of the different series of the above block polyelectrolyte copolymers have been investigated using static, dynamic and electrophoretic light scattering, turbidimetry, and fluorescence spectroscopy. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5790–5799, 2007     

Molecular dynamics of poly(ATRIF) homopolymer and poly(AN-co-ATRIF) copolymer investigated by dielectric relaxation spectroscopy

Aiming to develop new dielectric polymers containing CN and F groups with strong dipole moments, a novel copolymer of acrylonitrile (AN) and 2,2,2-trifluoroethyl acrylate (ATRIF) was synthesized in acetonitrile by free radical process as well as the respective homopolymer (poly(ATRIF)). The copolymer’s composition and microstructure were analyzed by FTIR, ¹H and ¹³C NMR spectroscopy and SEC. The molar incorporation of AN determined in the copolymer by NMR was 58 mol%. Thermogravimetric analysis of poly(AN-co-ATRIF) copolymer showed good thermal stability comparatively to the fluorinated homopolymer.Both copolymer, poly(AN-co-ATRIF), and homopolymer, poly(ATRIF), were dielectrically characterized over a frequency range from 10⁻¹ to 10⁶ Hz, and in a temperature range from 223 to 393 K. The dominating relaxation process detected in both materials is the α-relaxation, associated with the dynamic glass transition. A VFTH temperature dependence of the relaxation times (τ) was found for both materials, as characteristic of cooperative processes, from which the respective glass transition temperatures (T_g(τ = 100 s)) were estimated, which differ ∼40 K, the one of the copolymer being higher (307 K) in accordance to the calorimetric analysis. This effect was attributed to a higher stiffness of the backbone in the copolymer originated by the inclusion of the acrylonitrile groups. Both relaxation functions have the same breath of relaxation times allowing constructing a single master curve, indicating similar non-exponential character. A less fragile behavior was found for the copolymer. This was rationalized in a more straightforward way by the free volume approach instead from a correlation between fragility and intermolecular coupling. It was found that in the copolymer the free volume increases at a lower rate with the temperature increase. It was inferred from the VFTH temperature dependence of the dc conductivity and low values of the decoupling index that ion motion is significantly influenced by the dynamics of the α-process.     

Conformational studies of multichain copoly(α-amino acids)s in solution

The conformational transition of multichain copoly(-amino acid)s consisting of copoly(-methyl-L-glutamyl-L-lysine) as backbone molecule and poly(-benzyl-L-glutamate) as branch molecules was studied in chloroform and DCA mixtures. The helix stability of backbone molecule is strongly affected by the length of branch molecules. In the case of the multichain copolymer having short branch molecular chains, i.e.,DP _br <10, the helix conformation of the backbone molecule is strictly affected by some interferences among the randomly coiled molecular chains. In the case of water-soluble multichain copolymer having poly(L-glutamic acid) or poly(L-lysine) as branch molecules, the transitional process from coil to helix is observed by depressing hydrostatic repulsion among the ionized side chain of branch molecules. However, such conformational transition is depressed to a considerable extent by interferences among the branch molecules.Abbreviations used (shown alphabetically) A/I molar ratio of NCA to initiator - Cbz carbobenzyloxy - DCA dichloroacetic acid - DMF N,N-dimethylformamide - DP _br number-average degree of polymerization of branches of multichain copolymer - Fw _br weight fraction of-benzyl-L-glutamyl residues of multichain copolymer - Mn number-average molecular weight - NCA N-carboxy anhydride of-amino acid - ORD optical rotatory dispersion     

Non‐Resonant z‐Scan Characterization of the Third‐Order Nonlinear Optical Properties of Conjugated Poly(thiophene azines)

The nonlinear optical properties of a functionalized poly(thiophene azine), namely, poly(3,4‐didodecylthiophene azine), PAZ, at the optical telecommunication wavelength of 1550 nm are investigated by means of the closed‐aperture z‐scan technique in both thin films and solutions. Values of χ⁽³⁾=(2.4±0.4)×10^?13 esu, n₂=(4.0±0.7)×10^?15 cm² W^?1, and γ=(4.5±0.7)×10^?34 esu are estimated for the third‐order (Kerr) susceptibility, the intensity‐dependent refractive index, and the molecular second hyperpolarizability of solution samples, respectively. A very small dependence on the polymer chain length is found. Markedly higher values of (4.4±1.1)×10^?11 esu, (6.6±1.0)×10^?13 cm² W^?1, and (5.0±0.8)×10^?33 esu are measured for the corresponding quantities in thick (up to 20 μm) polymer films cast on quartz plates. The enhancement of the NLO responses on going from solution to solid samples is attributed to a partially ordered structure and to the presence of interchain interactions leading to greater π‐electron delocalization in the cast polymer films. The results are compared with those previously obtained by using third‐harmonic generation (THG), taking into account that those data were measured under conditions of three‐photon resonance, whereas our z‐scan measurements are fully off‐resonance.