Physical characterization of the rack effect and hydrogen bond networks in blue copper proteins

A summary of previous research is presented that indicates that the purpose of a blue copper protein's fold and hydrogen bond network, aka, the rack effect, enforce a copper(II) geometry around the copper(I) ion in the metal site. In several blue copper proteins, the C-terminal histidine ligand becomes protonated and detaches from the copper in the reduced forms. Mutants of amicyanin from Paracoccus denitrificans were made to alter the hydrogen bond network and quantify the rack effect by pK_a shifts.

The pK_a's of mutant amicyanins have been measured by pH-dependent electrochemistry. P94F and P94A mutations loosen the Northern loop, allowing the reduced copper to adopt a relaxed conformation: the ability to relax drives the reduction potentials up. The measured potentials are 265 (wild type), 380 (P94A), and 415 (P94F) mV vs. NHE. The measured pK_a's are 7.0 (wild type), 6.3 (P94A), and 5.0 (P94F). The additional hydrogen bond to the thiolate in the mutants is indicated by a red-shift in the blue copper absorption and an increase in the parallel hyperfine splitting in the EPR spectrum. This hydrogen bond is invoked as the cause for the increased stability of the C-terminal imidazole.

Melting curves give a measure of the thermal stability of the protein. A thermodynamic intermediate with pH-dependent reversibility is revealed. Comparisons with the electrochemistry and apoamicyanin suggest that the intermediate involves the region of the protein near the metal site. This region is destabilized in the P94F mutant; coupled with the evidence that the imidazole is stabilized under the same conditions confirms an original concept of the rack effect: a high energy configuration is stabilized at a cost to the rest of the protein.

Cell-targeted regulation of gene expression through synthetic RNA devices

The ability to interface with and program cellular function remains a challenging research frontier in biotechnology. Although the emerging field of synthetic biology has recently generated a variety of gene-regulatory strategies based on synthetic RNA molecules, few strategies exist through which to control such regulatory effects in response to specific exogenous or endogenous molecular signals. Here, we present the development of an engineered RNA-based device platform to detect and act on endogenous protein signals, linking these signals to the regulation of genes and thus cellular function.

We describe efforts to develop an RNA-based device framework for regulating endogenous genes in human cells. Previously developed RNA control devices have demonstrated programmable ligand-responsive genetic regulation in diverse cell types, and we attempted to adapt this class of cis-acting control elements to function in trans. We divided the device into two strands that reconstitute activity upon hybridization. Device function was optimized using an in vivo model system, and we found that device sequence is not as flexible as previously reported. After verifying the in vitro activity of our optimized design, we attempted to establish gene regulation in a human cell line using additional elements to direct device stability, structure, and localization. The significant limitations of our platform prevented endogenous gene regulation.

We next describe the development of a protein-responsive RNA-based regulatory platform. Employing various design strategies, we demonstrated functional devices that both up- and downregulate gene expression in response to a heterologous protein in a human cell line. The activity of our platform exceeded that of a similar, small-molecule-responsive platform. We demonstrated the ability of our devices to respond to both cytoplasmic- and nuclear-localized protein, providing insight into the mechanism of action and distinguishing our platform from previously described devices with more restrictive ligand localization requirements. Finally, we demonstrated the versatility of our device platform by developing a regulatory device that responds to an endogenous signaling protein.

The foundational tool we present here possesses unique advantages over previously described RNA-based gene-regulatory platforms. This genetically encoded technology may find future applications in the development of more effective diagnostic tools and targeted molecular therapy strategies.

Electron transfer in chemically and genetically modified myoglobins

The temperature dependences of the reduction potentials (E^o') of wildtype human myoglobin (Mb) and three site-directed mutants have been measured by using thin-layer spectroelectrochemistry. Residue Val68, which is in van der Waals contact with the heme in Mb, has been replaced by Glu, Asp, and Asn. At pH 7.0, reduction of the heme iron (III) in the former two proteins is accompanied by uptake of a proton by the protein. The changes in E^o', and the standard entropy (ΔS^o') and enthalpy (ΔH^o') of reduction in the mutant proteins were determined relative to values for wild-type; the change in E^o' at 25°C was about -200 millivolts for the Glu and Asp mutants, and about -80 millivolts for the Asn mutant. Reduction of Fe(III) to Fe(II) in the Glu and Asp mutants is accompanied by uptake of a proton. These studies demonstrate that Mb can tolerate substitution of a buried hydrophobic group by potentially charged and polar residues, and that such amino acid replacements can lead to substantial changes in the redox thermodynamics of the protein.

Through analysis of the temperature dependence and shapes of NMR dispersion signals, it is determined that a water molecule is bound to the sixth coordination site of the ferric heme in the Val68Asp and in the Val68Asn recombinant proteins while the carboxyl group of the sidechain of Glu68 occupies this position in Val68Glu. The relative rhombic distortions in the ESR spectra of these mutant proteins combined with H₂¹⁷O and spin interconversion experiments performed on them confirm the conclusions of the NMRD study.

The rates of intramolecular electron transfer (ET) of (NH₃)₅Ru-His48 (Val68Asp, His81GIn, Cys110AIa)Mb and (NH₃)₅Ru-His48 (Val68GIu,His81GIn,Cys110Ala)Mb were measured to be .85(3)s^-1 and .30(2)s^-1, respectively. This data supports the hypothesis that entropy of 111 reduction and reorganization energy of ET are inversely related. The rates of forward and reverse ET for (NH₃)₅ Ru-His48 (Val68GIu, His81 GIn, Cys110AIa)ZnMb -7.2(5)•10⁴s^-1and 1.4(2)•10⁵s^-1, respectively- demonstrate that the placement of a highly polar residue nearby does not significantly change the reorganization energy of the photoactive Zn porphyrin.

The distal histidine imidazoles of (NH₃)₄isnRu-His48 SWMb and (NH₃)₅Ru-His48 SWMb were cyanated with BrCN. The intramolecular ET rates of these BrCN-modified Mb derivatives are 5.5(6)s^-1 and 3.2(5)s^-1, respectively. These respective rates are 20 and 10 times faster than those of their noncyanated counterparts after the differences in ET rate from driving force are scaled according to the Marcus equation. This increase in ET rate of the cyanated Mb derivatives is attributed to lower reorganization energy since the cyanated Mb heme is pentacoordinate in both oxidation states; whereas, the native Mb heme loses a water molecule upon reduction so that it changes from six to five coordinate. The reorganization energy from Fe-OH₂ dissociation is estimated to be .2eV. This conclusion is used to reconcile data from previous experiments in our lab. ET in photoactive porphyrin-substituted myoglobins proceed faster than predicted by Marcus Theory when it is assumed that the only difference in ET parameters between photoactive porphyrins and native heme systems is driving force. However, the data can be consistently fit to Marcus Theory if one corrects for the smaller reorganization in the photoactive porphyrin systems since they do not undergo a coordination change upon ET.

Finally, the intramolecular ET rate of (NH₃)₄isnRu-His48 SWMb was measured to be 3.0(4)s^-1. This rate is within experimental error of that for (NH₃)₄pyrRu-His48 SWMb even though the former has 80mV more driving force. One likely possibility for this observation is that the tetraamminepyridineruthenium group undergoes less reorganization upon ET than the tetraammineisonicotinamideruthenium group. Moreover, analysis of the (NH₃)₄isnRu-His48 SWMb experimental system gives a likely explanation of why ET was not observed previously in (NH₃)₄isnRu-Cytochrome C.

Structural Characterization of Pro-inflammatory and Anti-inflammatory Immunoglobulin G Fc Proteins

Immunoglobulin G (IgG) is central in mediating host defense due to its ability to target and eliminate invading pathogens. The fragment antigen binding (Fab) regions are responsible for antigen recognition; however the effector responses are encoded on the Fc region of IgG. IgG Fc displays considerable glycan heterogeneity, accounting for its complex effector functions of inflammation, modulation and immune suppression. Intravenous immunoglobulin G (IVIG) is pooled serum IgG from multiple donors and is used to treat individuals with autoimmune and inflammatory disorders such as rheumatoid arthritis and Kawasaki’s disease, respectively. It contains all the subtypes of IgG (IgG1-4) and over 120 glycovariants due to variation of an Asparagine 297-linked glycan on the Fc. The species identified as the activating component of IVIG is sialylated IgG Fc. Comparisons of wild type Fc and sialylated Fc X-ray crystal structures suggests that sialylation causes an increase in conformational flexibility, which may be important for its anti-inflammatory properties.

Although glycan modifications can promote the anti-inflammatory properties of the Fc, there are amino acid substitutions that cause Fcs to initiate an enhanced immune response. Mutations in the Fc can cause up to a 100-fold increase in binding affinity to activating Fc gamma receptors located on immune cells, and have been shown to enhance antibody dependent cell-mediated cytotoxicity. This is important in developing therapeutic antibodies against cancer and infectious diseases. Structural studies of mutant Fcs in complex with activating receptors gave insight into new protein-protein interactions that lead to an enhanced binding affinity.

Together these studies show how dynamic and diverse the Fc region is and how both protein and carbohydrate modifications can alter structure, leading to IgG Fc’s switch from a pro-inflammatory to an anti-inflammatory protein.

A study of T=1, T=3/2, and T=2 states in some light nuclei using (He^3,n) reactions

The (He³, n) reactions on B¹¹, N¹⁵, O¹⁶, and O¹⁸ targets have been studied using a pulsed-beam time-of-flight spectrometer. Special emphasis was placed upon the determination of the excitation energies and properties of states with T = 1 (in Ne¹⁸), T = 3/2 (in N¹³ and F¹⁷) and T = 2 (in Ne²⁰). The identification of the T = 3/2 and T = 2 levels is based on the structure of these states as revealed by intensities and shapes of angular distributions. The reactions are interpreted in terms of double stripping theory. Angular distributions have been compared with plane and distorted wave stripping theories. Results for the four reactions are summarized below:

1) O¹⁶ (He³, n). The reaction has been studied at incident energies up to 13.5 MeV and two previously unreported levels in Ne¹⁸ were observed at E_x = 4.55 ± .015 MeV (Γ = 70 ± 30 keV) and E_x = 5.14 ± .018 MeV (Γ = 100 ± 40 keV).

2) B¹¹ (He³, n). The reaction has been studied at incident energies up to 13.5 MeV. Three T = 3/2 levels in N¹³ have been identified at E_x = 15.068 ± .008 MeV (Γ ˂ 15 keV), E_x = 18.44 ± .04, and E_x 18.98 ± .02 MeV (Γ = 40 ± 20 keV).

3) N¹⁵ (He³, n). The reaction has been studied at incident energies up to 11.88 MeV. T = 3/2 levels in F¹⁷ have been identified at E_x = 11.195 ± .007 MeV (Γ ˂ 20 keV), E_x = 12.540 ± .010 MeV (Γ ˂ 25 keV), and E_x = 13.095 ± .009 MeV (Γ ˂ 25 keV).

4) O¹⁸ (He³, n). The reaction has been studied at incident energies up to 9.0 MeV. The excitation energy of the lowest T = 2 level in Ne²⁰ has been found to be 16.730 ± .006 MeV (Γ ˂ 20 keV).

Angular distributions of the transitions leading to the above higher isospin states are well described by double stripping theory. Analog correspondences are established by comparing the present results with recent studies (t, p) and (He³, p) reactions on the same targets.

Identification of the main allergen sensitizers in an Iran asthmatic population by molecular diagnosis

Background: There has been a significant growth in the prevalence of allergy, mainly associated to IgE-mediated disorders such as asthma and rhinitis. The identification of atopy in asthmatic patients through the measurement of specific IgE can help to identify risk factors that cause asthmatic symptoms in patients. The development and use of individualized allergen-based tests by the Component Resolved Diagnosis has been a crucial advance in the accurate diagnosis and control of allergic patients. The objective of this work was to assess the usefulness of molecular diagnosis to identify environmental allergens as possible factors influencing the development and manifestation of asthma in a group of asthmatic patients from Iran. Methods: Studied population: 202 adult asthmatic patients treated at the Loghman Hakim Hospital and Pasteur Institute of Teheran (Iran) from 2011 to 2012. Specific IgE determined by the ImmunoCAP system were used to both evaluate the patients' atopic condition and the molecules involved in the allergic sensitization. SDS-PAGE IgE-immunoblotting associated with mass spectrometry was carried out to study the cockroach IgE-binding sensitizing proteins. Results: Forty-five percent of all patients could be considered atopic individuals. Eighty-two percent of atopic patients were sensitized to pollen allergens. The Salsola kali (Sal k 1) and the Phleum pratense (rPhl p 1 and/or rPhl p 5) major allergens were the most common sensitizers among pollens (71% and 18%, respectively). Thirty-five percent of the atopic population was sensitized to cockroach. Four different allergens, including a previously unknown alpha-amylase, were identified in the cockroach extract. No significant associations could be demonstrated between the severity of asthma and the specific IgE levels in the atopic population. Statistical analysis identified the Sal k 1 as the main protein allergen influencing the development and expression of asthma in the studied population. Conclusions: Pollen and cockroach were the most relevant allergen sources in the asthmatic population. The Salsola kali major allergen was the main cause for sensitization in the atopic patients suffering asthma. Using the Component Resolved Diagnosis, it was possible to identify a new Blattella germanica cockroach allergen (Blattella alpha amylase 53 kDa) that could sensitize a relevant percentage of this population.

Estudo dos componentes metabólicos, hormonais, marcadores inflamatórios e função microvascular em crianças com excesso de peso

Estudos da microcirculação cutânea demonstram que a disfunção microvascular neste sítio está relacionada a diversos fatores de risco cardiovascular. Existem poucos estudos avaliando a reatividade microvascular em crianças e a interferência da puberdade está presente na maioria deles. O objetivo deste estudo foi avaliar se a disfunção microvascular está presente em crianças pré-púberes com excesso de peso através da técnica de videocapilaroscopia de leito periungueal. Realizou-se um estudo transversal com 52 obesos, 18 sobrepesos e 28 eutróficos, com idade de 7,44 1,22 anos. Avaliou-se o comportamento dos fatores de risco e a função microvascular. A reatividade microvascular foi testada através da avaliação da densidade capilar funcional, da velocidade de deslocamento das hemácias em repouso e após uma isquemia de 1 min, e do tempo de reperfusão durante a hiperemia reativa. Análise de função disciminante canônica foi utilizada de forma multivariada para testar a possibilidade de separação dos grupos conforme o grau de adiposidade. Nos pacientes estudados não observamos diferença na reatividade microvascular, em nenhuma da variáveis testadas. Conforme esperado, os grupos obeso e sobrepeso apresentavam maiores valores para a circunferência da cintura (p<0,001), a relação cintura/altura (p<0,001), a pressão arterial média (p<0,001), o homeostasis model assessment for insulin resistance (HOMA-IR) (p<0,001) e os níveis de insulina (p<0,001), leptina (p<0,0001), glicose (p=0,02), triglicerídeos (p<0,05), colesterol total (p=0,004), ácido úrico (p=0,007) e proteína C reativa (p<0,0001) do que os eutróficos. A análise multivariada demonstrou a associação de variáveis metabólicas, antropométricas e microvasculares, sendo que estas foram separadas pelo grau de adiposidade corporal. Concluímos que nessa população estudada, apesar das diferenças nos perfis metabólico, inflamatório e hormonal, não houve diferença na reatividade microvascular. Entretanto, a associação entre variáveis clínico-antropométricas com aquelas relacionadas com a reatividade microvascular esteve presente nestas crianças pré-púberes e o grau de adiposidade corporal foi capaz de influenciar estas associações.

Papel regulatório da proteína anexina-1 e de seu derivado Ac2-26 no modelo experimental de asma alérgica em camundongos

A asma é uma doença inflamatória crônica caracterizada por hiper-reatividade das vias aéreas, acúmulo de eosinófilos, secreção de muco e remodelamento. No decorrer do estabelecimento do processo inflamatório, há liberação de mediadores endógenos que atuam limitando a evolução do quadro patológico e garantindo a manutenção da homeostasia (COHN, ELIAS e CHUPP, 2004). Dentre estes recebem destaque os hormônios glicocorticóides, reconhecidos por sua atividade anti-inflamatória, dependente, em parte, da geração de fatores intermediários como a proteína anexina-1 (AnxA1) (KAMAL, FLOWER e PERRETTI, 2005; PERRETTI, 2003). Neste estudo investigou-se o papel regulatório da AnxA1 e do peptídeo derivado Ac2-26 (50 - 200 g/animal) no modelo experimental de asma alérgica murina. Camundongos BALB/c (AnxA1+/+) e depletados do gene codificante para AnxA1 (AnxA1-/-) foram sensibilizados com ovoalbumina (OVA 50 g) e hidróxido de alumínio (5 mg), por via subcutânea. Após 14 dias, foi feito reforço com OVA (25 g), por via intraperitoneal, e nos dias 19, 20 e 21 foram desafiados com OVA (25 g), por via intranasal. O tratamento consistiu na administração intranasal do peptídeo Ac2-26 (50 - 200 g), 1 h antes de cada desafio. As análises foram feitas 24 h após o último desafio e incluíram: i) função pulmonar (resistência e elastância) e hiper-reatividade das vias aéreas à metacolina (3 27 mg/ml) através de pletismografia invasiva; ii) alterações morfológicas através de histologia clássica; iii) quantificação de colágeno e iv) quantificação de mediadores inflamatórios através de ELISA. Verificou-se que camundongos AnxA1-/-, quando ativamente sensibilizados e desafiados com OVA apresentaram exacerbação do quadro de hiper-reatividade das vias aéreas, assim como do número de eosinófilos no lavado broncoalveolar e no infiltrado peribrônquico, deposição de colágeno e nos níveis de IL-13 em comparação aos controles AnxA1+/+. Em paralelo, observou-se que o peptídeo Ac2-26 levou a uma redução da hiper-reatividade das vias aéreas frente à estimulação com metacolina nos animais AnxA1+/+. O peptídeo Ac2-26 reduziu o infiltrado inflamatório no parênquima pulmonar e o número de eosinófilos peribronquiolares, além da produção de muco no tecido pulmonar e da geração IL-4, IL-13, eotaxina-1 e -2. Em conjunto, nossos achados mostram que os camundongos AnxA1-/- mostraram-se mais responsivos à estimulação antigênica, o que foi indicativo de que a AnxA1 parece exercer um papel regulatório importante sobre a resposta inflamatória alérgica murina. Além disso, o efeito inibitório do peptídeo Ac2-26 sobre a resposta alérgica pulmonar foi indicativo de que este se coloca como um composto anti-inflamatório e anti-alérgico promissor para utilização na terapia da asma.

3.0～2.0Ma B. P.南海南部深海沉积物孢粉记录及其对全球变化的响应

为了重建东亚季风区域2.5MaB.P.前后植被和气候变化的历史，更好地了解低纬度地区植被变化及其对全球变化的响应，本研究选择了南海南部ODP1143站深海沉积物中的孢粉样品进行研究。通过高分辨率（7ka）的孢粉样品的分析研究，建立起3.0～2.0MaB.P.时段南海深海沉积孢粉组合序列，系统建立了这一时段植被演替序列。在此基础上，重点研究了2.5MaB.P.前后气候变化在南海周边地区植被演替中的响应，为探索和揭示东亚古季风及古环境演变提供了孢粉学依据。 ODP 1143站位于南沙海区，北纬9º22´，东经113º17´，深海柱状样采于水深2772m的大陆坡。本研究以生物地层学和氧同位素年代学为依据建立了年龄框架，对1143站135～95m（3.0～2.6 Ma B. P.）深海沉积中的孢粉样品进行了分析，建立了3.0～2.0MaB.P.时段南海深海沉积孢粉组合序列。孢粉样品处理方法主要是用盐酸去掉钙质和氢氟酸浸泡溶解硅质后，再用筛子将样品在超声波发生器中震荡过滤。孢粉的鉴定和统计在光学透视显微镜下完成。研究结果表明： 1、孢粉谱的主要特征是沉积率变化显著。与3.0～2.6 Ma B. P. 相比，2.6～2.0 Ma B. P.各类型花粉及孢子沉积率均有显著提高。该结果表明2.6 Ma B. P.南海海平面有显著下降，可与北半球冰盖形成、东亚季风增强相对应。 2、2.6 Ma B. P.以来，各类型孢粉沉积率变化与深海氧同位素分期相对应，代表了多次冰期-间冰期旋回。该结果表明南海海平面曾有多次上升和下降。 3、频谱分析结果表明，3.0～2.0 Ma B. P.存在0.1 Ma（偏心率）和46.9ka（斜率）的周期。

放牧对内蒙古草原植物C:N:P化学计量特征和资源分配的影响

C、N、P是生物地球化学循环中的重要元素，其可利用性和各元素之间的平衡关系将生态系统的物质循环有机统一为一个整体。化学计量生态学为研究这几种基本元素间的平衡提供了一个有力的理论框架。许多研究表明，过度放牧会改变生态系统的结构和功能，而放牧如何影响植物的C:N:P化学计量关系的却少见报道。本研究以内蒙古锡林河流域沿水分梯度分布的草甸、草甸草原、典型草原和沙地四种植被类型中的灰脉苔草（Carex appendiculata）、贝加尔针茅(Stipa baicalensis)、羊草(Leymus chinensis)、大针茅(Stipa grandis)、小叶锦鸡儿(Caragana microphylla)、冷蒿(Artemisia frigid)、克氏针茅(S. krylovii)和榆树(Ulmus Pumila)疏林沙地8个草地群落为研究对象，对长期禁牧样地和自由放牧样地中273种植物，其中禁牧与放牧样地中的共有植物种为144个，测定了植物叶片C: N: P化学计量特征以及植株高度、丛幅面积、茎、叶和株（丛）生物量、茎叶比等功能性状，系统地研究了放牧对植物C:N:P化学计量特征和资源分配的影响。取得了如下主要研究结果和结论： 1. 放牧降低了植物叶片的C:N比，但增加了N:P比和C:P比。C:N:P 化学计量比的变化主要受叶片N和P含量变化的影响； 2. 植物C:N:P化学计量特征对放牧的响应同时受水分条件的制约。沿水分梯度分布的不同植被类型中，植物叶片C:N:P化学计量特征对放牧的响应不同。草甸群落中，植物叶片C含量显著降低，N和P含量显著增加；在草甸草原群落中，植物叶片C、P含量减少，N含量显著增加；而在典型草原群落中，植物叶片C、N和P含量均显著降低； 3. 在物种水平上，C、N、P含量对放牧的响应分为：显著增加、显著降低和没有显著变化三种类型。放牧影响下，植物叶片N含量和N:P比在显著升高的物种多于显著降低的，而叶片C含量、C:N和C:P显著降低的物种占的比例很小，表明植物对放牧适应策略与物种本身的生物学特性有着密切的关系。 4. 过度放牧使植物的植株高度、丛幅大小、株丛数、茎叶比和单株生物量均显著降低，即植物整体呈现小型化现象，进而导致群落初级生产力、茎和叶生物量下降。轻度放牧对物种的资源分配没有显著影响，单株（丛）生物量和群落茎、叶及总生物量均呈增加趋势，这与过度放牧的影响正好相反。 5. 过度放牧显著改变了物种的资源分配策略，使生物量向叶的分配比例增加，向茎的分配比例减少。资源优先向同化器官分配可能是草地植物对长期放牧干扰的一种重要适应对策。

Frog albumin is expressed in skin and characterized as a novel potent trypsin inhibitor

A novel potent trypsin inhibitor was purified and characterized from frog Bombina maxima skin. A full-length cDNA encoding the protein was obtained from a cDNA library constructed from the skin. Sequence analysis established that the protein actually comprises three conserved albumin domains. B. maxima serum albumin was subsequently purified, and its coding cDNA was further obtained by PCR-based cloning from the frog liver. Only two amino acid variations were found in the albumin sequences from the skin and the serum. However, the skin protein is distinct from the serum protein by binding of a haem b (0.95 mol/mol protein). Different from bovine serum albumin, B. maxima albumin potently inhibited trypsin. It bound tightly with trypsin in a 1: 1 molar ratio. The equilibrium dissociation constants (K-D) obtained for the skin and the serum proteins were 1.92 x 10(-9) M and 1.55 x 10(-9) M, respectively. B. maxima albumin formed a noncovalent complex with trypsin through an exposed loop formed by a disulfide bond (Cys(53)-Cys(62)), which comprises the scissile bond Arg(58)(P-1)-His(59)(P-1'). No inhibitory effects on thrombin, chymotrypsin, elastase, and subtilisin were observed under the assay conditions. Immunohistochemical study showed that B. maxima albumin is widely distributed around the membranes of epithelial layer cells and within the stratum spongiosum of dermis in the skin, suggesting that it plays important roles in skin physiological functions, such as water economy, metabolite exchange, and osmoregulation.

D77, one benzoic acid derivative, functions as a novel anti-HIV-1 inhibitor targeting the interaction between integrase and cellular LEDGF/p75

Integration of viral-DNA into host chromosome mediated by the viral protein HIV-1 integrase (IN) is an essential step in the HIV-1 life cycle. In this process, Lens epithelium-derived growth factor (LEDGF/p75) is discovered to function as a cellular co-fa

1,5-二氮杂戊二烯合成非对称联吡啶研究

联吡陡及其衍生物不仅用于化工和药物合成的中间体，而且具有独特的赘合作用，可被用于金属催化剂配体等方面，因此它的合成方法研究引起了人们广泛的兴趣。但是非对称联吡陡的合成日前方法仍很少。本文利用己经被成功使用于其他含氮杂环的二碳合成子-1，5-二氮杂戊二烯（vinamidiniulnsalts），合成了单取代的2，2'-，2，3'-，2，4，一二类联吡陡。在合成1，5-二氮杂戊二烯的过程中：确立了一条以四甲氧基丙烷为原料一步合成l，5一二氮杂戊二烯的简捷，经济，易工业化的合成路线，并成功进行了公斤级的放大实验；优化了1，5-二氮杂戊二烯的亲电取代反应，高收率的获得溟代，硝化的1，5-二氮杂戊二烯；优化了从取代乙酸合成p取代1，5-二氮杂戊二烯的合成方法，高收率的获得九种p芳基取代1，5-二氮杂戊二烯。本文研究了非对称联吡睫合成的一种新方法：在碱性条件下，取代的1，5-二氮杂戊二烯盐各种乙酞基吡陡亲核加成的产物，不经分离直接和氨进行［3＋2＋1〕的成环反应，可以高收率的合成出单取代的2，2气，2，3气，2，4气三类联吡陡。这一方法己经被成功的应用于芳基取代，卤素取代，硝基取代以及无取代基的1，5-二氮杂戊二烯与三种乙酞基吡陡的反应。这种成环反应的收率与1，5-二氮杂戊二烯俘位的吸电子特征相关。因此，针对不同取代基的1，5-二氮杂戊二烯在溶剂，碱的选择以及反应温度的控制等方面进行了优化。从而成功合成出近30种单取代的非对称联吡陡。一这种合成方法，原料价格低廉，实验操作简单，而且收率高，非常适合大量合成的要求。

Syntheses, crystal structures, visible and near-IR luminescent properties of ternary lanthanide (Dy3+, Tm3+) complexes containing 4,4,4-trifluoro-1-phenyl-1,3-butanedione and 1,10-phenanthroline

The ligands 4,4,4-trifluoro-1-phenyl-1.3-butanedione (Hbfa) and 1,10-phenanthroline (phen) were used to prepare ternary lanthanide (Ln) complexes [Dy(bfa)(3)phen and Tm(bfa)(3)phen]. Crystal data: Dy(bfa)(3)phen C(42)H(26)FqN(2)O(6)Dy, triclinic, P (1) over bar, a= 9.9450(6) angstrom, b = 14.0944(9) angstrom, c = 14.6043(9) angstrom, alpha = 82.104(1)degrees, beta = 87.006(1)degrees, gamma = 76.490(1)degrees, V = 1971.1(2)angstrom(3), Z = 2; Tm(bfa)(3)phen C42H26F9N2O6Tm, triclinic, P (1) over bar, a = 9.898(5)angstrom, b = 13.918(5)angstrom, c = 14.753(5)angstrom, a = 83.517(5)degrees, alpha = 86.899(5)degrees, gamma = 76.818(5)degrees, V = 1965.3(14)angstrom(3), Z = 2. The coordination number of the central Ln(3+) (Ln = Dy, Tm) ion is eight, with six oxygen atoms from three Hbfa ligands and two nitrogen atoms from the phen ligand.

Supramolecular architectures, photophysics, and electroluminescence of 1,3,4-oxadiazole-based iridium(III) complexes: From mu-dichloro bridged dimer to mononuclear complexes

One mu-dichloro bridged diiridium complex and three mononuclear iridium(III) complexes based on the 1,3,4-oxadiazole derivatives as cyclometalated ligands and acetylacetonate (acac) or dithiolates O,O'-diethyldithiophosphate (Et(2)dtp) or N,N'-diethyldithiocarbamate (Et(2)dtc) as ancillary ligands have been synthesized and systematically studied by X-ray diffraction analysis. The results reveal that three mononuclear complexes all adopt distorted octahedral coordination geometry around the iridium center by two chelating ligands with cis-C-C and trans-N-N dispositions, which have the same coordination mode as the diiridium dimer. The dinuclear complex crystallizes in the monoclinic system and space group C2/c, whereas three mononuclear iridium complexes are all triclinic system and space group P(1) over bar. In the stacking structure of the dimer, one-dimensional tape-like chains along the b-axis are formed by hydrogen bondings, which are strengthened by pi stacking interactions between phenyl rings of 1,3,4-oxadiazole ligands. Then these chains assemble a three-dimensional alternating peak and valley fused wave-shape structure. In each stacking structure of three mononuclear complexes, two molecules form a dimer by the C-H center dot center dot center dot O hydrogen bondings, and these dimers are connected by pi stacking interactions along the b-axis, constructing a zigzag chain.