苯酚助力可见光诱导铜催化下氨基酸衍生物的不对称脱氨芳基化反应

<正>α-氨基酸作为一种常见的生物质广泛存在于自然界中,在合成化学中也有广泛的应用.它们不仅是蛋白质的基本组成部分,而且还可以通过二次代谢转化为各种生物活性分子.在合成化学中,手性氨基酸通常用作蛋白质和肽合成的构建模块以及有机催化剂和配体的手性源.因此,氨基酸的高价值转化一直是合成化学家们关注的焦点^[1].近年来,可见光诱导的单电子转移(SET)过程可以生成具有高反应活性的开壳自由基中间体,为氨基酸的不对称转化提供了新的可能^[2].2016年,MacMillan和Fu团队^[3]利用手性镍催化剂首次实现了氨基酸的不对称脱羧芳基化(Scheme 1,a).此外,     

具有不同电荷和手性的Co(Ⅲ)配合物跨人红细胞膜的动力学研究

研究了4种不同电荷的Co(Ⅲ)金属配合物跨人红细胞膜的动力学,并测定了它们跨人红细胞膜的一级反应动力学速率常数,发现[Co(C₂O₄)₃]^3-的跨膜速率明显高于[Co(en)₃]³⁺,[Co(en)₂(C₂O₄)]⁺和[Co(en)(C₂O₄)₂]^-,后3种配合物的跨膜速率常数随正电荷的减少略有增加,跨膜机制为简单扩散.[Co(C₂O₄)₃]^3-的跨膜速率受阴离子通道抑制剂DIDS明显抑制,抑制率为51.95%,推测其跨膜机制为部分经阴离子通道协同简单扩散过膜.人红细胞摄入L-[Co(C₂O₄)₃]^3-的速率明显大于D-[Co(C₂O₄)₃]^3-,显示了一定的手性选择性.     

自旋标记荧光探针表征生物活性分子的自由基损伤

生命过程中产生的经基自由基(^˙OH)已引起广泛关注.目前,对于^˙OH的研究主要集中在直接对^˙OH进行定量表征^[1~3]和问接检测^˙OH诱导损伤生物大分了的损伤产物.^˙OH诱导损伤生物大分了,能够产生大量的碳中心自由基^[4,5].     

零电流示波电位滴定盐酸异丙嗪

盐酸异丙嗪是一种较重要的抗组胺药,现行的分析标准为非水滴定法^[1],此外尚有分光光度法^[2]、伏安法^[3]、电极法^[4]、液相色谱法^[5]和流动注射分析法^[6]等。本文将高鸿提出的零电流示波电位滴定法^[7]中的铂片电极修饰一层含四苯基硼酸-异丙嗪电活性物质的PVC膜,使电极对异丙嗪产生响应,可用于四苯基硼酸钠直接滴定异丙嗪的终点指示。     

12-钨硼酸5-氟尿嘧啶盐的合成及抗癌活性研究

5-氟尿嘧啶(5-Fu)是一种阻止肿瘤细胞嘧啶类核苷酸合成的抗代谢药物,对多种肿瘤有较好的疗效.但该药首次代谢效应显著,毒副作用较大,且治疗剂量与中毒剂量接近,使其临床应用受到一定限制.为降低毒性,提高其活性,人们从多方面对5-Fu进行化学修饰,设计合成出许多新药^[1～4].近年来,多金属氧酸盐因结构独特,在抗病毒、抗肿瘤等方面的应用已引起人们的广泛重视^[5～7].王晓红等^[8,9]曾先后报道了杂多钨酸盐的体内、外抗肿瘤活性.多金属氧酸具有较强的接受电子的能力^[10],能与含有N,S和O原子的有机基质作用形成新型化合物^[11～14].     

毛细管电泳同时测定肌肽、鹅肌肽和高肌肽

肌肽类生物活性肽为含组氨酸的二肽,是一类重要的神经递质,具有调节酶的活性以及螯合重金属等重要生物学功能,对老年性白内障的治疗以及受伤肌肤的康复都有独特作用.测定这类物质的方法主要有高效液相色谱法^[1~3]和离子交换色谱法^[4]等.     

对-氯甲基苯乙烯共聚物引发合成接枝共聚物

接枝共聚物含有性质差别很大的主链和支链,具有许多特殊的性质,因而一直是人们感兴趣的研究课题之一^[1～5].原子转移自由基聚合(ATRP)^[6,7]的问世,为接枝共聚物的合成提供了一条新的途径.本文用对-氯甲基苯乙烯和其它乙烯基单体自由基共聚.     

四(4-重氮基苯基)卟啉的合成及其与聚苯乙烯磺酸钠自组装的研究

卟啉是一类重要的功能性小分子染料,近年来,在光化学治疗^[1,2]、光电转换^[3,4]、传感元件^[5]、烯烃环氧化催化剂^[6]和光敏化剂^[7]等方面的研究与应用引起了人们的广泛注意.通过两亲卟啉分子衍生物,或带有负电荷的卟啉衍生物,特别是带磺酸基的卟啉分子与正离子聚电解质自组装,制备带有卟啉结构单元的LB膜和自组装膜已有很多报道^[8～14].     

双(O,O-二芳基硫代磷酰基)多硫物的合成

双(O,O-二芳基硫磷酰基)多硫物(Ⅰ)具有杀虫作用^[1]、增效作用^[2,3]、杀菌作用^[4],亦可用作橡胶硫化剂^[5]。R为芳基的I,除几个双二硫物(I,n=2)^[6,7]外,文献中尚未有记载,为探索它们的杀菌活性,我们用下列反应由(Ⅱ)或(Ⅲ)合成了17个行为2,3和4,R为芳基、卤代芳基的I。     

正丁胺等离子体膜TSM声波传感器的性能研究

等离子体聚合物在结构上与普通的聚合物显著不同,它能形成含有活性基团的高度交联的网络结构,从而具有良好的均匀性及对基质的附着性^[1,2].有关采用等离子体聚合膜的TSM传感器的报道不多^[3,4].     

Sb2O3与HZSM-5的相互作用

研究了氮气气氛下于500℃处理2h后的Sb₂O₃/HZSM-5体系中Sb₂O₃在分子筛表面上的分散行为.发现处理后的体系中Sb₂O₃晶相消失,HZSM-5晶相减少,非晶相增加.经XRD相定量、氮气吸附、正己烷吸附及NH₃-TPD实验可知,高温下酸性Sb₂O₃破坏了分子筛的部分骨架,生成无定形硅铝胶,同时Sb₂O₃高分散在其中.含Sb₂O₃的无定形硅铝胶修饰了分子筛表面,减小了孔口,提高了分子筛在甲苯烷基化反应中的择形性能,对二甲苯的选择性可高达89.     

A novel mitochondria-targeting tetrapeptide for subcellular delivery of nanoparticles

A novel mitochdrial-targeting tetrapeptide, RF-2(D-Arg-Dmt-Arg-Phe-NH₂) had been developed, which showed controlled toxicity and excellent protection against gentamicin-induced hair cell damage, and more importantly, exhibited superior guidance towards mitochondrion achieved by its modified nanoparticles.     

Enzyme-Instructed Assemblies Enable Mitochondria Localization of Histone H2B in Cancer Cells

Presently, little is known of how the inter-organelle crosstalk impacts cancer cells owing to the lack of approaches that can manipulate inter-organelle communication in cancer cells. We found that a negatively charged, enzyme cleavable peptide (MitoFlag) enables the trafficking of histone protein H2B, a nuclear protein, to the mitochondria in cancer cells. MitoFlag interacts with the nuclear location sequence of H2B to block it from entering the nucleus. A protease on the mitochondria cleaves the Flag from the MitoFlag/H2B complex to form assemblies that retain H2B on the mitochondria and facilitate H2B entering the mitochondria. Adding NLS, replacing aspartic acid by glutamic acid residues, or changing the l - to d -aspartic acid residue on MitoFlag abolishes the trafficking of H2B into mitochondria of HeLa cells. As the first example of the enzyme-instructed self-assembly of a synthetic peptide for trafficking endogenous proteins, this work provides insights for understanding and manipulating inter-organelle communication in cells.     

一对具有DNA切割功能的新型酰胺对映体

设计合成一对新型的丝氨酸-组胺酰胺对映体化合物L-Ser-Hism和D-Ser-Hism,发现它们具有明显的DNA切割活性,切割反应的最佳pH范围为6.0～6.5.L-Ser-Hism的切割活性比D-Ser-Hism的强.与丝组二肽相比,这对酰胺对映体未显示出明显的切割蛋白活性,表明其对DNA的优先切割功能.     

聚苯乙烯-丙烯酸嵌段共聚物在不同pH值和Ca2+浓度下的胶束行为

近年来, 对具有纳米尺寸的聚合物自组装结构的研究日益增多. 其中, 嵌段共聚物在选择性溶剂中的胶束行为研究得最为广泛和深入[1~5]. 纳米胶束表现出诸多常规尺寸材料所不具备的特殊性能, 在材料化学、生物医学以及环境科学等领域有广阔的应用前景. Webber等[6]对聚丙烯酸和聚苯乙烯接枝共聚物的研究发现, 聚合物的接枝率和聚合物浓度以及溶液离子强度对胶束结构有影响; Eisenberg等[1,7]对不同嵌段比例的苯乙烯-丙烯酸嵌段共聚物的自组装行为进行研究发现, 不同嵌段比例所对应的胶束结构不同. 胶束形成的环境对胶束的形成与稳定性的影响是人们研究的重点. 本文报道了聚苯乙烯-丙烯酸嵌段共聚物在水中的胶束行为, 着重讨论了溶液pH值和钙离子浓度对聚丙烯酸链段相互作用的影响.     

Protection of mitochondrial integrity from oxidative stress by selenium-containing glutathione transferase

The antioxidant activity of a novel artificial glutathione peroxidase-like enzyme, selenium-containing glutathione 5-transferase from Lucilia cuprina (seleno-LuGST1-1), was studied by using a ferrous sulfate/ascorbate-induced mitochondrial damage model system. Swelling of mitochondria, lipid peroxidation, and cytochrome-c oxidase activity were selected to evaluate the preservation of mitochondrial integrity in this system. Seleno-LuGST1-1 could effectively protect the mitochondria against oxidative damage in a dose-dependent manner and exhibited both higher catalytic activity and greater antioxidant ability than the classic mimic, 2-phenyl-1,2-benziososelenazol-3(2H)-one (Ebselen). This novel artificial biocatalyst therefore may have great protential for pharmacologic application in the treatment of reactive oxygen species-related diseases.     

溶胶—凝胶法制备NiO／SiO2催化剂研究

分别以正硅酸乙酯、硝酸镍为硅源和镍源,采用溶胶－凝胶法,经超临界流体干燥和普通干燥制备了NiO-A-SiO2、NiO-G-SiO2催化剂;以气凝胶和干凝胶为载体,采用浸渍法制备了NiO/A-SiO2、NiO/G-SiO2催化剂。并用XRD、TEM、BET、TPR等手段,研究了制备方法对催化剂织构、结构和Ni物种存在形态的影响,发现NiO-A-SiO2和NiO-G-SiO2催化剂上高度分散的NiO簇团与SiO2之间有较强的相互作用,其顺酐液相选择加氢转化率低于10％;NiO/G-SiO2催化剂上,以单一物种形态存在的NiO与SiO2相互作用弱,顺酐转化率为42％;NiO/A-SiO2催化剂上,以多种形态存在的微量NiO与SiO2间的相互作用较复杂,其顺酐液相选择加氢的转化率和丁二酸酐的选择性分别可达100％和98％。     

在负载H3PO4的固体上3,3,4-三甲基-4-戊烯-2-酮的催化合成

3,3,4-Trimethyl-4-penten-2-one has been synthesized by the acylation of 2,3-dimethyl-2-butene with acetic anhydride in the presence of soild-supported H3PO4.By comparison of the acylation reactions of 2,3-dimethyl-2-butene with acetic anhydride over various soilds-supported H3PO4,it was found that K10 clay,silicagel,HY zeolite and HMordenite were good supports.The results obtined indicate that the soild-supported small amounts of H3PO4 possessed higher catalytic activities,For obatining a higher yield of 3,3,4-trimethyl-4-penten-2-one different supports required different modification methods.     

Phase state of iron system colloidal catalyst in butadiene polymerization

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Enzyme‐Instructed Assemblies Enable Mitochondria Localization of Histone H2B in Cancer Cells

Presently, little is known of how the inter‐organelle crosstalk impacts cancer cells owing to the lack of approaches that can manipulate inter‐organelle communication in cancer cells. We found that a negatively charged, enzyme cleavable peptide (MitoFlag) enables the trafficking of histone protein H2B, a nuclear protein, to the mitochondria in cancer cells. MitoFlag interacts with the nuclear location sequence of H2B to block it from entering the nucleus. A protease on the mitochondria cleaves the Flag from the MitoFlag/H2B complex to form assemblies that retain H2B on the mitochondria and facilitate H2B entering the mitochondria. Adding NLS, replacing aspartic acid by glutamic acid residues, or changing the l ‐ to d ‐aspartic acid residue on MitoFlag abolishes the trafficking of H2B into mitochondria of HeLa cells. As the first example of the enzyme‐instructed self‐assembly of a synthetic peptide for trafficking endogenous proteins, this work provides insights for understanding and manipulating inter‐organelle communication in cells.