具有生物活性的人带3蛋白胞质片段融合蛋白的克隆、表达与纯化

用PCR法从质粒pHB3中扩增了人红细胞带3蛋白胞质片段(CDB3)基因.PCR产物经限制性内切酶切割后与多克隆位点处带有编码6个组氨酸序列的高效表达载体pET28b连接,构建为重组子pCDBHistag.重组子经酶切及序列测定后在大肠杆菌BL21(DE3)中获得高效表达,可溶性目的蛋白占菌体总蛋白的40%左右.C端带有6个连续组氨酸的带3蛋白胞质片段作为融合蛋白不仅可以降低宿主菌蛋白酶对其水解程度,而且简化了目的蛋白的纯化过程.经一步螯合Ni²⁺的亲和层析获得了电泳纯的带3蛋白胞质片段融合蛋白.活性测定结果表明,带3蛋白胞质片段融合蛋白能够抑制醛缩酶(Aldolase)活性的70%,与文献报道的人红细胞内带3蛋白胞质片段具有相同的功能.     

Li2B4O7-MgCl2(B)-H2O体系热力学性质的等压研究及离子相互作用模型

采用等压法测定了298.15 K下Li-Mg-Cl-borate-H2O体系离子强度范围为0.0581～0.6320 mol*kg-1, MgCl2不同离子浓度分数的等压摩尔平衡浓度、水活度,计算了Li2B4O7和MgCl2混合溶液的饱和水蒸汽压、渗透系数等热力学性质.考虑了在不同的总硼浓度范围的硼酸(H3BO3)和硼氧配阴离子[B(OH)-4, B3O3(OH)-4, B4O5(OH)2-4]的不同生成反应平衡.由实验结果对修正的Pitzer渗透系数方程进行了参数化研究,提出了一简化的参数化模型,减少了模型的经验参数量,获得了锂、镁、氯离子与硼物种组合之间、及不同硼氧配阴离子之间的组合相互作用参数,用该模型计算的渗透系数值与实验结果取得合理的一致性,从而将离子作用模型扩展到对含硼、锂、镁的复杂体系的表述.对完善含锂、硼的盐湖卤水体系的热力学模型和盐湖资源的综合开发利用具有重要意义.     

稀土离子Tb~(3+)对卵清蛋白稳定性的影响

在室温、p H=7.4、10 mmol/L 4-羟乙基哌嗪乙磺酸(Hepes)缓冲溶液条件下,利用荧光光谱研究了卵清蛋白(Ova)与Tb~(3+)的结合性质.利用荧光探针2-对甲苯胺基-6-萘磺酸钠(TNS)检测了Tb~(3+)对Ova疏水区的影响.通过化学变性实验分析了Ca2+和Tb~(3+)对Ova结构稳定性的影响.结果表明,Ova可以与Tb~(3+)形成1∶2的复合物,Tb~(3+)的结合使其疏水区暴露程度增加,TNS的荧光增强.Ova的解折叠曲线呈现三态的变化(N■■I■■U).Ca2+可以增加I■■U过程的稳定性,Tb~(3+)对N■■I和I■■U两个解折叠过程都有影响.     

四元交互体系Li+,Na+//CO2-3,B4O72一-H2O 298 K相关系的理论预测及实验研究

采用三元体系的溶解度数据,运用多元线性回归法拟合了Li 2CO3(a),Na 2CO3(b),Li 2B4O7(c)的单盐参数、溶解平衡常数及有关的混合离子作用参数.它们的值分别为:β(o)a=-1.235 5,β(1)a=-2.654 6,Cφa=-0.004 660 7,β(0)b=-3.030 6,β(1)b=-3.023 8,Cφb=-0.290 89,β(0)c=-0.293 04,β(1)c=2.155 6,Cφc=-0.004 256 0,θLi,Na=1.041 8,θB.C=-2.630 5,ψLi,Na,C=-0.063 91,ψLi,Na,B=0.493 56,ψLi,B,C=-0.478 42,ΨNa,B,c=0.306 16,In K(Li2CO 3)=-8.962 9,In K(Na2CO3@10H2O)=3.064 6,ln K(Li2B4O 7@3H2O)=-7.356 6,ln K(Na2B4O7@10H2O)=-7.477 8.以盐的溶解平衡常数为判据,运用Pitzer方程计算了四元体系Li+,Na+//CO2-3,B4O2-7-H2O 298 K时的溶解度,并采用等温溶解平衡法,对该体系298 K时溶解度进行了实验测定,同计算值相比,二者基本吻合.     

桑蚕丝素-RGD融合蛋白的固态结构及其细胞粘附性分析

利用基因工程方法把含有短肽RGD的氨基酸序列连接到桑蚕丝素蛋白的结晶序列GAGAGS上, 通过调节DNA的聚合度, 合成了具有[TGRGDSPA(GVPGV)₂GG(GAGAGS)₃AS]_n一级结构、不同分子量大小的桑蚕丝素-RGD融合蛋白, 并且通过在M9培养基中添加[3-¹³C]Ala的方法进行融合蛋白的稳定同位素标记. ¹³C CP/MAS NMR结果显示, 融合蛋白中的GAGAGS部分具有与天然桑蚕丝素结晶部分相同的分子结构, 即Silk I处理后为均一的分子结构, 而Silk II处理后为不均一的分子结构, 它包含了三种不同的结构成分. 另一方面, 通过对小鼠成纤维细胞BALB/3T3在不同蛋白材料载体上的粘附和增殖性能的测定结果显示, 融合蛋白对细胞的增殖性能与天然胶原蛋白相近, 但表现出了比胶原蛋白更好的细胞粘附性能. 该研究结果显示, 如果对该桑蚕丝素-RGD融合蛋白进行适当加工, 可能适合于组织工程支架材料的应用.     

B位掺杂GdCo1-xSrxO3的制备及其光催化活性

用柠檬酸络合法制备了钙钛矿型GdCo1-XSrXO3(X=0.00, 0.02, 0.04, 0.06, 0.08)复合氧化物, 通过XRD, TEM 等手段对所生成纳米晶的物相结构、微观形貌、颗粒大小等进行了表征. 结果表明, 所合成的颗粒为钙钛矿型纳米晶, 球形. 通过其对活性艳红 X-3B 降解对其光催化活性进行了研究, 实验结果表明在B 位掺杂 Sr2+ 后使GdCoO3 的光催化活性明显提高, 当X=0.06 时, 即GdCo0.94Sr0.06O3 的光催化活性最佳.     

Na_6PMo_(11)FeO_(40)对小鼠黑色素瘤B16细胞内黑色素合成抑制及抑菌活性研究

研究了过渡金属取代的Kiggen型结构的杂多酸盐Na_6PMo_(11)FeO_(40)对体外培养的小鼠黑色素瘤B16细胞的生物学效应,并分析了其对4种细菌的抗菌活性.结果显示:不同浓度的Na_6PMo_(11)FeO_(40)对B16细胞的细胞形态和数量有不同程度的影响,对B16细胞的增殖率、酪氨酸酶活性以及黑色素合成量的抑制呈现出明显的浓度效应.浓度为50~200μmol/L的Na_6PMo_(11)FeO_(40)能显著抑制B16细胞增殖(P0.05或P0.01);浓度为200μmol/L的Na_6PMo_(11)FeO_(40)对酪氨酸酶活性抑制极显著(P0.01),IC50为166.5μmol/L;Na_6PMo_(11)FeO_(40)对藤黄八叠球菌、金黄色葡萄球菌、枯草芽孢杆菌和大肠杆菌均有抗菌作用,且对球菌的抑制效果优于杆菌.实验结果表明,Na_6PMo_(11)FeO_(40)可作为具有防腐抑菌功能的新型酪氨酸酶抑制剂.     

4-苯基-1,3-硒唑衍生物的合成及其对蛋白酪氨酸磷酸酯酶-1B抑制活性

蛋白酪氨酸磷酸酯酶-1B(PTP1B)是抗糖尿病治疗的重要靶点,因此创制活性优良的PTP1B抑制剂具有重要意义。 本文设计并合成了11个含1,3-硒唑和1,2,4-三唑活性组块新型结构目标分子(ZLXZ1-ZLXZ11),并利用傅里叶变换红外光谱仪(FTIR)、核磁共振波谱仪(NMR)和高分辨质谱(HRMS)等对其进行了结构表征。 首先选择ZLXZ1和ZLXZ11在MOE 2015.10程序上,与PTP1B进行分子对接模拟,结果表明,在ZLXZ1分子中硒唑环上的硒原子与PTP1B中副催化位点Tyr46、Ala217、Lys120和Asp 48分别形成了π-H作用和氢键作用。 在ZLXZ11分子中硒唑上的硒原子与PTP1B中Asp181、Arg221和Asp48形成了氢键作用。 在分子对接模拟的基础上,测试了11个目标分子的抑制活性,结果表明,所有目标分子的抑制率均在87.02%以上,其中3个目标分子PTP1B抑制活性高于阳性参照物齐墩果酸,抑制活性优良,有望成为潜在的PTP1B抑制剂。     

Dielectric characterization of B3 and B4 phases

Dielectric measurements on two samples formed from banana-shaped molecules with terminal alkyl or alkyloxy groups were carried out in a frequency range between 10^-3 Hz and 10 MHz. Both samples exhibit B₂ and B₃ phases; one of them has a B₄ state as well. As usual, two ranges of relaxation were detected in the B₂ phase, the fast reorientation about the long axes of the molecules and a slow collective process. Only one dielectrically active low frequency process could be separated in the B₃ and B₄ phases; this is probably related to the dynamics of superstructures. The high frequency limit of the dielectric constants gives a hint that neither phase is a classical solid. A quite strong increase in the conductivity at the transition into the B₃ phase is critically discussed.     

Dielectric characterization of the B7 and a BX phase

The first clear experimental evidence of a dielectric relaxation in the B₇ phase is given. The associated molecular process is probably the reorientation of the bent-shaped molecules about the long molecular axis. It is also shown that the dielectric constant strongly increases at the phase transition I-B₇ pointing to a co-operative motion of ferroelectric clusters. Furthermore, a phase transition B₇-B_X is observed. The values of about 10 for the high frequency limit of the dielectric constants of the B₇ and B_X phases and the static dielectric constants of the isotropic phase are in agreement. Thus, in all the phases the main dipoles can reorient faster than 10^-8 s, i.e. the experimental limit. Only in the supercooled B_X phase were the dynamics of the transversal dipoles measured. Using atomic force microscopy, focal-conic domains modulated by parallel lines have been observed at room temperature.     

Site-selective Csp3-H aryloxylation of natural product Tanshinone IIA and its analogues

A novel catalyst-free Csp³-H aryloxylation approach allowing for rapid installation of a wide range of aryloxyl groups regioselectively at the C-4 position of Tanshinone IIA under simple and mild conditions was developed. This unique protocol exhibited atom-/step-economy, low cost, high efficiency and robust functional-group tolerance, which will greatly facilitate to diversify the A-ring of the bioactive natural product.     

K2B4O7-Na2B4O7-Li2B4O7-H2O四元体系273 K介稳相平衡

采用等温蒸发平衡法研究了四元体系K2B4O7-Na2B4O7-Li2B4O7-H2O在273 K时的介稳相平衡及平衡液相的密度. 研究发现该四元体系为简单共饱和型, 无复盐及固溶体形成, 根据溶解度数据绘制了相图, 相图中有一个共饱点E, 三条单变度曲线E3E, E2E, E1E; 三个平衡固相分别为K2B4O7·4H2O、Na2B4O7·10H2O 和LiBO2·8H2O. 并简要讨论了实验结果.     

Synthesis and characterization of 7-(CH3)3N-4- {2,4-(NO2)2C6H3S}-nido-7-CB10H11 and its Biodistribution in C57B16 Mice Bearing B16 Melanoma

7-(CH₃)₃N-4-{2,4-(NO₂)₂C₆H₃S}-nido-7-CB₁₀H₁₁ has been synthesized through a Friedel-Crafts substitution reaction on 7-(CH₃)3N-nido-7- CB₁₀H₁₂. A biodistribution study in mice with implanted B16 melanoma indicates that the compound locates in neoplastic tissue at concentrations which suggest that its use in ¹⁰B neutron capture therapy may be feasible.     

Azatricarbaborane 7-t-Bu-arachno-7,1,5,12-NC3B8H12 and Parent Tricarbaboranes nido-[5,6,9-C3B7H10]- and -5,6,9-C3B7H11

The neutral azatricarbaborane 7-t-Bu-arachno-7,1,5,12-NC(3)B(8)H(12), isolated as a side product (yield 2%) from the new synthesis of 7-t-BuNH2-nido-7,8,9-C(3)B(8)H(10) (yield 70%), can be easily converted to the first parent representatives of the 10-vertex nido family of tricarbaboranes, [5,6,9-C(3)B(7)H(10)]- and 5,6,9-C(3)B(7)H(11).     

Phase Equilibria of Quaternary System NaCl-NaBr-Na2B4O7-H2O at 348 K

The phase equilibria of quaternary system NaCl-NaBr-Na₂B₄O₇-H₂O at 348 K were studied by the isothermal equilibrium method. The solubilities and densities of the equilibrium solution were determined. According to the experimental data, the phase diagram, density-composition diagrams and water content diagram of the quaternary system at 348 K were plotted respectively. And the phase diagram consists of one univariant curve, two crystallization fields and without any invariant point of the quaternary system. The equilibrium solid phases of the two crysta- llization fields were Na(Cl, Br) and Na₂B₄O₇·5H₂O. The experimental results show that the quaternary system contained solid solution. The densities of the solution decrease with increasing NaCl concentration and increase with increasing NaBr concentration.     

Insights into Conformational Dynamics and Allostery in DNMT1-H3Ub/USP7 Interactions

DNA methyltransferases (DNMTs) including DNMT1 are a conserved family of cytosine methylases that play crucial roles in epigenetic regulation. The versatile functions of DNMT1 rely on allosteric networks between its different interacting partners, emerging as novel therapeutic targets. In this work, based on the modeling structures of DNMT1-ubiquitylated H3 (H3Ub)/ubiquitin specific peptidase 7 (USP7) complexes, we have used a combination of elastic network models, molecular dynamics simulations, structural residue perturbation, network modeling, and pocket pathway analysis to examine their molecular mechanisms of allosteric regulation. The comparative intrinsic and conformational dynamics analysis of three DNMT1 systems has highlighted the pivotal role of the RFTS domain as the dynamics hub in both intra- and inter-molecular interactions. The site perturbation and network modeling approaches have revealed the different and more complex allosteric interaction landscape in both DNMT1 complexes, involving the events caused by mutational hotspots and post-translation modification sites through protein-protein interactions (PPIs). Furthermore, communication pathway analysis and pocket detection have provided new mechanistic insights into molecular mechanisms underlying quaternary structures of DNMT1 complexes, suggesting potential targeting pockets for PPI-based allosteric drug design.     

Dielectric characterization of samples showing the SmCPA/B7 transition

Dielectric measurements on samples consisting of banana-shaped molecules with a polymorphism I/SmCP_A/B₇ have been performed for the first time. The dielectric increment for the reorientation of the molecules about the long axis, and the corresponding relaxation time, surprisingly decrease at the SmCP_A/B₇ transition. This effect is discussed in terms of the undulated structure which partially destroys the ferroelectric short range order. Decreasing temperature gives an even stronger hindrance for this reorientation and could explain controversial results obtained in the B₇ phases of different samples. At lower temperatures a further mesophase was detected. This was additionally observed by calorimetric and atomic force microscopy methods.     

Isomeric ammonio derivatives of nido-carborane 3- and 10-H3N-7,8-C2B9H11

Abstract

Structure of 3-ammonio derivative of nido-carborane 3-NH₃-7,8-C₂B₉H₁₁ was determined by single crystal X-ray diffraction. The isomeric 10-ammonio derivative 10-NH₃-7,8-C₂B₉H₁₁ was prepared by the treatment of the corresponding ethylnitrilium derivative 10-EtC≡N-7,8-C₂B₉H₁₁ with hydrazine hydrate in acetonitrile.