反相离子对色谱法分析3′, 5′反向寡核苷酸

3′,5′反向寡核苷酸是碱基组成和长度完全相同、碱基顺序相反的两个寡核苷酸序列。以三乙胺为离子对试剂,研究了缓冲液浓度(0.025～0.15 mol/L)、pH (5.0～6.8)、柱温(25～45 ℃)、流速(0.3～0.7 mL/min)以及不同初始洗脱强度和洗脱梯度条件下,6个3′,5′反向寡核苷酸模拟样品保留和分离的变化特点。三组反向序列在缓冲液浓度为0.05 mol/L,pH 6.8和流速0.4 mL/min条件下获得最大分离,温度对分离的影响不大,而初始洗脱强度对反向序列的影响远大于洗脱梯度。实验结果表明3′,5′反向寡核苷酸的分离和保留趋势不完全一致,色谱条件的优化应有利于实现样品在柱上的弱保留。研究结果还显示寡核苷酸序列中5′末端的保留强于3′末端。     

Proton Nuclear Magnetic Resonance Measurements of 2′-Aminodeoxyuridylyl-3′,5′-Deoxyuridine

A dideoxyribonucleotide, 2′-amino-2′-deoxyuridylyl 3′,5′-deoxyuridine, containing an unsual base (2′-amino-2′-deoxyuridine) that isresistant to nucleases was investigated by ′H NMR. The pK_a of the protonation of the amino group (5.8) was determined by profiles of chemical shifts of protons in the vicinity of amino group versus pH. However, protonation of the amino group has little effect on the conformation of the dimer, assumed to be B-form DNA. This conclusion is drawn from the chemical shift data and coupling constants of H₁-H₂. Thus, 2′-amino-2′-deoxyuridine can be used in antisense and anticode oligonucleotides.     

Sequence-based analysis of 5′UTR and coding regions of CASP3 in terms of miRSNPs and SNPs in targetting miRNAs

Apoptosis is described as a mechanism of cell death occurring after adequate cellular harm. Deregulation of apoptosis occurs in many human conditions such as autoimmune disorders, ischemic damage, neurodegenerative diseases and different cancer types. Information relating miRNAs to cancer is increasing. miRNAs can affect development of cancer via many different pathways, including apoptosis. Polymorphisms in miRNA genes or miRNA target sites (miRSNPs) can change miRNA activity. Although polymorphisms in miRNA genes are very uncommon, SNPs in miRNA-binding sites of target genes are quite common. Many researches have revealed that SNPs in miRNA target sites improve or decrease the efficacy of the interaction between miRNAs and their target genes. Our aim was to specify miRSNPs on CASP3 gene (caspase-3) and SNPs in miRNA genes targeting 5′UTR and coding exons of CASP3, and evaluate the effect of these miRSNPs and SNPs of miRNA genes with respect to apoptosis. We detected 141 different miRNA binding sites (126 different miRNAs) and 7 different SNPs in binding sites of miRNA in 5′UTR and CDS of CASP3 gene. Intriguingly, miR-339-3p’s binding site on CASP3 has a SNP (rs35372903, G/A) on CASP3 5′UTR and its genomic sequence has a SNP (rs565188493, G/A) at the same nucleotide with rs35372903. Also, miR-339-3p has two other SNPs (rs373011663, C/T rs72631820, A/G) of which the first is positioned at the binding site. Here, miRSNP (rs35372903) at CASP3 5′UTR and SNP (rs565188493) at miR-339-3p genomic sequence cross-matches at the same site of binding region. Besides, miR-339-3p targets many apoptosis related genes (ZNF346, TAOK2, PIM2, HIP1, BBC3, TNFRSF25, CLCF1, IHPK2, NOL3) although it had no apoptosis related interaction proven before. This means that miR-339-3p may also have a critical effect on apoptosis via different pathways other than caspase-3. Hence, we can deduce that this is the first study demonstrating a powerful association between miR-339-3p and apoptosis upon computational analysis.     

In silico prediction of human genes as potential targets for rice miRNAs

BackgroundExogenous microRNAs (miRNAs) enter the human body through food, and their effects on metabolic processes can be considerable. It is important to determine which miRNAs from plants affect the expression of human genes and the extent of their influence.MethodThe binding sites of 738Oryza sativa miRNAs (osa-miRNAs) that interact with 17 508 mRNAs of human genes were determined using the MirTarget program.ResultThe characteristics of the binding of 46 single osa-miRNAs to 86 mRNAs of human genes with a value of free energy (ΔG) interaction equal 94%–100% from maximum ΔG were established. The findings showed that osa-miR2102-5p, osa-miR5075-3p, osa-miR2097-5p, osa-miR2919 targeted the largest number of genes at 38, 36, 23, 19 sites, respectively. mRNAs of 86 human genes were identified as targets for 93 osa-miRNAs of all family osa-miRNAs with ΔG values equal 94%–98% from maximum ΔG. Each miRNA of the osa-miR156-5p, osa-miR164-5p, osa-miR168-5p, osa-miR395-3p, osa-miR396-3p, osa-miR396-5p, osa-miR444-3p, osa-miR529-3p, osa-miR1846-3p, osa-miR2907-3p families had binding sites in mRNAs of several human target genes. The binding sites of osa-miRNAs in mRNAs of the target genes for each family of osa-miRNAs were conserved when compared to flanking nucleotide sequences.ConclusionTarget mRNA human genes of osa-miRNAs are also candidate genes of cancer, cardiovascular and neurodegenerative diseases.     

In situ surface plasmon study of the electropolymerization of Fe(vbpy)3 onto a gold surface

Sequential multilayer electropolymerization of Fe(vbpy)₃²⁺ (vbpy=4-vinyl-4′-methyl-2,2′-bipyridine) onto a thin gold electrode was followed in situ with surface plasmon spectroscopy (SPS) using a 1 mW HeNe laser at 6328 Å. The robustness of the gold film electrode necessary for electrochemical deposition in 0.10 M tetraethylammonium perchlorate+acetonitrile is imparted by use of a thin film of 3-mercaptopropyl-trimethoxysilane attached to a SF10 slide to which the metal is covalently bonded. As each polymer layer is deposited by cycling a potentiostat from 0.0 to −1.75 and back to 0.0 V, a plasmon spectrum (reflectivity versus prism angle) is obtained. SP analysis of the angular shift of the spectrum, which increases as the polymer layer thickens, yields an estimate of both the thickness and index of refraction of the polymer film. We found that the plasmon spectrum shifts to higher angles as the polymer layer thickens, along with a progressive decrease in the depth of the resonance minimum. Our modeling shows this unusual spectral behavior involving the resonance minimum is consistent with a Fe(vbpy)₃²⁺ chromophore absorption at 6328 Å, along with thickening of the polymer film. This work demonstrates that SPS is a viable in situ technique for obtaining thickness measurements of electrodeposited thin films.     

Unexpected isolation and structural characterization of a redox-active Fe(II) piano-stool complex with an η-dppe ligand

A new cationic complex [(η²-bipy)(η⁵-C₅Me₅)Fe(η¹-dppe)][BPh₄] featuring a pendant free diphenylphosphine arm has been isolated in good yield after reaction of 2,2′-bipyridine with the known chloro precursor complex (η²-dppe)(η⁵-C₅Me₅)FeCl in presence of NaBPh₄. This complex which can be envisioned as a new redox-active building-block has been structurally characterized.     

Purine 3′:5′‐cyclic nucleotides with the nucleobase in a syn orientation: cAMP,cGMP and cIMP

Purine 3′:5′‐cyclic nucleotides are very well known for their role as the secondary messengers in hormone action and cellular signal transduction. Nonetheless, their solid‐state conformational details still require investigation. Five crystals containing purine 3′:5′‐cyclic nucleotides have been obtained and structurally characterized, namely adenosine 3′:5′‐cyclic phosphate dihydrate, C₁₀H₁₂N₅O₆P·2H₂O or cAMP·2H₂O, (I), adenosine 3′:5′‐cyclic phosphate 0.3‐hydrate, C₁₀H₁₂N₅O₆P·0.3H₂O or cAMP·0.3H₂O, (II), guanosine 3′:5′‐cyclic phosphate pentahydrate, C₁₀H₁₂N₅O₇P·5H₂O or cGMP·5H₂O, (III), sodium guanosine 3′:5′‐cyclic phosphate tetrahydrate, Na⁺·C₁₀H₁₁N₅O₇P⁻·4H₂O or Na(cGMP)·4H₂O, (IV), and sodium inosine 3′:5′‐cyclic phosphate tetrahydrate, Na⁺·C₁₀H₁₀N₄O₇P⁻·4H₂O or Na(cIMP)·4H₂O, (V). Most of the cyclic nucleotide zwitterions/anions [two from four cAMP present in total in (I) and (II), cGMP in (III), cGMP⁻ in (IV) and cIMP⁻ in (V)] are syn conformers about the N‐glycosidic bond, and this nucleobase arrangement is accompanied by C_rib—H…N_pur hydrogen bonds (rib = ribose and pur = purine). The base orientation is tuned by the ribose pucker. An analysis of data obtained from the Cambridge Structural Database made in the context of syn–anti conformational preferences has revealed that among the syn conformers of various purine nucleotides, cyclic nucleotides and dinucleotides predominate significantly. The interactions stabilizing the syn conformation have been indicated. The inter‐nucleotide contacts in (I)–(V) have been systematized in terms of the chemical groups involved. All five structures display three‐dimensional hydrogen‐bonded networks.     

Identification of evolutionarily conserved Momordica charantia microRNAs using computational approach and its utility in phylogeny analysis

Momordica charantia (bitter gourd, bitter melon) is a monoecious Cucurbitaceae with anti-oxidant, anti-microbial, anti-viral and anti-diabetic potential. Molecular studies on this economically valuable plant are very essential to understand its phylogeny and evolution. MicroRNAs (miRNAs) are conserved, small, non-coding RNA with ability to regulate gene expression by bind the 3′ UTR region of target mRNA and are evolved at different rates in different plant species. In this study we have utilized homology based computational approach and identified 27 mature miRNAs for the first time from this bio-medically important plant. The phylogenetic tree developed from binary data derived from the data on presence/absence of the identified miRNAs were noticed to be uncertain and biased. Most of the identified miRNAs were highly conserved among the plant species and sequence based phylogeny analysis of miRNAs resolved the above difficulties in phylogeny approach using miRNA. Predicted gene targets of the identified miRNAs revealed their importance in regulation of plant developmental process. Reported miRNAs held sequence conservation in mature miRNAs and the detailed phylogeny analysis of pre-miRNA sequences revealed genus specific segregation of clusters.     

Identification of Three New Flavonoids from the Peels of Citrus unshiu

Three new flavonoids, 5,6,7,8,3′,4′‐hexamethoxyhomoflavone ( 1 ), 5,6,7,8,4′‐pentamethoxyhomoflavone ( 2 ) and 3,6,7,8,2′,5′‐hexamethoxyflavone ( 3 ) were isolated from the peels of mature fruits of Citrus unshiu Marcow (Rutaceae), together with the three known compounds 6,7,8,4′‐tetramethoxyflavone (=6,7,8‐trimethoxy‐2‐(4‐methoxyphenyl)‐4H‐1‐benzopyran‐4‐one), 3,5,7,8,2′,5′‐hexamethoxyflavone (=2‐(2,5‐dimethoxyphenyl)‐3,5,7,8‐tetramethoxy‐4H‐1‐benzopyran‐4‐one), and scopoletin (=7‐hydroxy‐6‐methoxy‐2H‐1‐benzopyran‐2‐one) of which the former two have never been isolated from natural resources, although they have been reported as synthetic compounds. The structures of 1 – 3 were elucidated on the basis of spectroscopic evidence, including 1D‐ and 2D‐NMR analysis.     

Eu3+-Tb3+共掺杂SiO2-B2O3-Na2O-Y2O3-P2O5玻璃陶瓷的制备与发光性能

采用高温熔融法制备Eu3+?Tb3+共掺杂SiO2?B2O3?Na2O?Y2O3?P2O5前驱体玻璃。对前驱体玻璃粉末进行差示扫描量热(DSC)分析,确定玻璃陶瓷样品的热处理温度。前驱体玻璃热处理后,采用X射线衍射(XRD)和扫描电镜(SEM)分析可知前驱体玻璃中有Na3.6Y1.8(PO4)3晶粒析出。利用荧光光谱对玻璃陶瓷样品的发光性能进行表征,同时分析了Tb3+离子的荧光衰减曲线,确定Eu3+、Tb3+离子的发光机理以及能量传递过程。通过对Eu3+?Tb3+共掺杂玻璃陶瓷样品的发射光谱采集并用色坐标软件和色温计算程序,获得玻璃陶瓷样品的色坐标和相关色温。     

Building Functionality into 4′‐Hydrazone Derivatives of 2,2′: 6′,2″‐Terpyridine

The syntheses of the five 2,2′: 6′,2″‐terpyridine (tpy) ligands 5 – 9 functionalized in the 4′‐position with a hydrazone substituent RR′C?N? NH (R=R′=Me; R=H, R′=4‐BrC₆H₄, 4‐O₂NC₆H₄, 4‐MeOC₆H₄, or 3,5‐(MeO)₂C₆H₃) are described. Protonation of the tpy domain of the ligands is facile. Solution behaviour has been studied by NMR and electronic spectroscopies. Representative structural data are presented for neutral and monoprotonated ligands, and illustrate that H‐bonding involving the formal amine NH unit is a dominant structural motif in all cases.     

New results in the ammonolysis of hexafluoro-cyclo-triphosphazene: Crystal structure of P3N3F5–NH–P3N3F4NH2

The reaction of hexafluoro-cyclo-triphosphazene P₃N₃F₆ with ammonia in acetonitrile has been studied. New compounds, (2-imino-2,4,4,6,6-pentafluoro-2λ⁵,4λ⁵,6λ⁵-cyclo-triphosphaza-1,3,5-trienyl)-2-amino-4,4,6,6-tetrafluoro-2λ⁵,4λ⁵,6λ⁵-cyclo-triphosphaza-1,3,5-triene, P₃N₃F₅–NH–P₃N₃F₄NH₂ (2) and cis and trans isomers of non-gem-2,4-diamino-2,4,6,6-tetrafluoro-2λ⁵,4λ⁵,6λ⁵-cyclo-triphosphaza-1,3,5-triene, P₃N₃F₄(NH₂)₂ (4, 5)_, were detected by GC/MS, and ³¹P NMR spectroscopy in reaction mixtures. X-ray diffraction analysis of P₃N₃F₅–NH–P₃N₃F₄NH₂ (2) revealed two conformational polymorphs, 2A and 2B, the latter being built up of two different conformers that were further denoted as 2B_a (the same as the single conformer in 2A) and 2B_b. The compound 2 was characterized by spectroscopic methods and its 2D potential energy surface (PES) was described by density functional theory computations depending on two dihedral angles. The calculated PES spans over 30 kJ/mol in energy including 8 local minima and all first and second order saddle points. The occurrence of the two experimentally observed conformers 2B_a and 2B_b seems to be governed by crystal packing effects.     

Silyl Modification of Biologically Active Compounds. 9. Synthesis and Biological Activity of Novel 1,3-Disilabenzo[5,6]cyclohexene Derivatives

We have synthesized a series of 1,3-disilabenzo[5,6]cyclohexene derivatives starting from (o-bromomethylphenyl)dimethylchlorosilane. Based on NMR data, we have concluded that there is a transannular N Si interaction in the 3',3'-5-trimethyl-2,8-dioxa-5-aza-1-silacyclooctane-1-spiro-1'-(1',3'-disilabenzo[4',5']cyclohexene) obtained. We have studied the psychotropic activity of this compound and its iodomethylate and also 3-(3-chloropropyl)-1,1,3-trimethyl-1,3-disilabenzo[5,6]cyclohexene, and we have shown that they have a sedative effect.     

Neue Spiroverbindungen aus Cyclophosphazenen und Cyclodi[phosphadiazan]en

New Spiro Compounds from Cyclophosphazenes and Cyclodi[phosphadiazanes] Chlorocyclophosphazenes (Cl₂P = N)₃ and (Cl₂p = N)₄ react with dihydrazidophosphoric acid derivatives in THF in the presence of triethylamine to give the spirocyclic compounds Cl₄N₃P₃(NHN(CH₃))₂P(S)OC₆H₅, Cl₆N₄P₄(NHNH)₂P(S)OC₆H₅. Constitutions have been confirmed by MS, NMR, IR and elemental analysis.