砷捕捉刻蚀剂反应速率常数研究

采用约束刻蚀剂层技术（ＣＥＬＴ）有可能实现纳米级的超微加工目的￣［１，２］。约束刻蚀层形成的方法之一是：通过电化学反应在模板表面上产生刻蚀剂，其在向外扩散过程中即与其它未有刻蚀作用的溶液组分发生快速均相化学反应，从而使刻蚀剂失去活性，刻蚀剂的扩散层厚度可约束在紧靠模板的范围内。而ＣＥＬＴ技术则取决于产生能对特定材料具有高度腐蚀性的腐蚀剂和具有合理的清除反应体系；象强氧化剂溴，邻菲绕啉铁（Ⅲ）和过氧化氢等均可作为刻蚀剂，Ｂａｒｄｅｔａｌ￣［３］等研究者借助扫描电化学显微镜（ＳＥＣＭ）通过电化学产生的溴和邻菲绕啉铁（Ⅲ）直接来刻蚀进行微加工，但未采用约束刻蚀层技术，所刻的线条较宽。本文研究溴和邻菲绕啉铁（Ⅲ）的均相捕捉反应速率常数，为利用约束刻蚀层技术进行微加工打下必要的基础

Research Progress of α-Glucuronidase, an Enzyme for Degrading Hemicellulose Side-Chain

半纤维素是自然界中最丰富的可再生资源之一,将半纤维素降解为单糖并转化为燃料或化学品一直是科学界研究的热点。半纤维素是由木糖基主链以及α-葡萄糖醛酸等侧链共同组成的异质多聚体。α-葡萄糖醛酸酶是半纤维素完全降解过程中的关键酶之一,能够水解4-O-甲基葡萄糖醛酸与木糖之间的α-1,2-糖苷键。本文综述了α-葡萄糖醛酸酶的分类、催化机制及晶体结构、酶学性质和基因克隆表达等方面的研究进展,同时对该研究进行了展望。Hemicellulose is one of the most abundant renewable resources in nature.The bioconversion of hemicellulose into biofuels or chemicals is a research hotspot in the world.Hemicellulose consists of a backbone of xylan residues and some branches like glucuronic acid.α-Glucuronidase, which is capable to hydrolysis the α-1,2-glycosidic bond between xylan and glucuronic acid, is one of the key enzyme to degrade hemicellulose completely.The recent research progresses on catalysis mechanism, structure, charaterization, and gene cloning of α-glucuronidase are summarized in this paper.国家自然科学基金(31170067;21303142); 国家重点基础研究发展计划(973计划;2010CB732201); 福建省自然科学基金(2012J05029); 农业部“引进国际先进农业科学技术”项目(2013-Z70

Cloning and heterologous expression of a novel GH10 xylanase gene from Hypocrea orientalis EU7-22

木聚糖酶是降解半纤维素最主要的酶,对于开发可再生生物能源具有重要的应用价值。分别以东方肉座菌(HyPOCrEA OrIEnTAlIS)Eu7-22的基因组dnA和C dnA为模板,利用染色体步移和PCr技术首次克隆获得该菌gH10家族木聚糖酶Ⅲ的基因(XynⅢ),并对其进行生物信息学分析。结果表明:该基因全长1283 bP(gXynⅢ),含有3个内含子;CdS序列为1044 bP(CXynⅢ),编码347个氨基酸,n端含有一个16 AA的信号肽序列;XynⅢ氨基酸序列与TrICHOdErMA PSEudOkOnIngII的EndOXylAnASE具有较高的同源性。经生物信息学分析,XynⅢ成熟蛋白可能含有18个n-糖基化位点,其理论等电点(P I)为6.14,蛋白质分子质量为36.55 ku,属于亲水性蛋白;SWISS-MOdEl建模预测,XynⅢ成熟蛋白中含有11个α螺旋,其核心结构为8个β折叠片围成一个柱状结构。同时将编码成熟蛋白的基因片段MXynⅢ与P PIC9k质粒连接构建表达载体后转化毕赤酵母,对重组子表达产物进行酶活检测显示该基因能在毕赤酵母中表达有生物活性的XynⅢ并分泌到胞外,发酵液中的木聚糖酶活在诱导培养168 H后可达到127.5 Iu/M l。Endo-1,4-xylanase( E.C.3.2.1.8) is the major enzyme to the conversion of hemicelluloses into xylo-oligosaccharide.In this research,a novel GH10 xylanase Ⅲ( xyn Ⅲ) gene was cloned from Hypocrea orientalis EU7-22 by chromosome walking and PCR.The results showed that the DNA fragment( 1283 bp) encoding xynⅢ( gxynⅢ) contained three introns.The CDS of xynⅢ( cxynⅢ) encoded 331 amino acids of putative mature protein and a 16 aa signal in N terminator.The amino acid sequence of xynⅢ is highly homologous with the endoxylanase of Trichoderma pseudokoningii.The bioinformatics analysis showed that the theoretical isoelectric point and the molecular weight of putative mature protein of XYNⅢ were 6.14 and 36.55 ku,respectively.It is a soluble hydrophilic protein containing 18 N-glycosylation sites.The 3D structure predicted with SWISS-Model showed that XYNⅢ protein contained11 alpha helices and 8 extended strands.A recombinant plasmid p PIC9K-xynⅢ was constructed and then transformed into Pichia pastoris.The transformant identified by PCR was induced to produce XYNⅢ enzyme with 1% methanol.And after 168 hours induced expression,the produced crude enzyme was detected to reach a high enzymatic activity of 127.5 IU / m L.国家自然科学基金(21303142;31170067); 福建省海洋高新产业发展专项项目(闽海洋高新[2014]25号); 厦门市海洋经济发展专项资金项目(14GZP59HJ29

The Determination of the Reaction Rate Constant of As(Ⅲ)Scavenging Etchant

采用约束刻蚀剂层技术（ＣＥＬＴ）有可能实现纳米级的超微加工目的￣［１，２］。约束刻蚀层形成的方法之一是：通过电化学反应在模板表面上产生刻蚀剂，其在向外扩散过程中即与其它未有刻蚀作用的溶液组分发生快速均相化学反应，从而使刻蚀剂失去活性，刻蚀剂的扩散层厚度可约束在紧靠模板的范围内。而ＣＥＬＴ技术则取决于产生能对特定材料具有高度腐蚀性的腐蚀剂和具有合理的清除反应体系；象强氧化剂溴，邻菲绕啉铁（Ⅲ）和过氧化氢等均可作为刻蚀剂，Ｂａｒｄｅｔａｌ￣［３］等研究者借助扫描电化学显微镜（ＳＥＣＭ）通过电化学产生的溴和邻菲绕啉铁（Ⅲ）直接来刻蚀进行微加工，但未采用约束刻蚀层技术，所刻的线条较宽。本文研究溴和邻菲绕啉铁（Ⅲ）的均相捕捉反应速率常数，为利用约束刻蚀层技术进行微加工打下必要的基础。The mechanisms of the arsenite acid scavenging bromine and[Fe(Phen_3)]￣(3+)reaction were studied by the electrochemical methods. The arsenite acid scavenging bromine and[Fe(Phen_3)]￣(3+) reaction rate constants in sulfuric acid in the range of 23℃ to 69℃ and in the range of19℃ to 69℃ were determined by measuring the steady state limiting current,respectively.Theactivation energy of the arsenite acid scavenging bromine reaction in sulfuric acid is 33 kJ·mol￣(-1).作者联系地址：厦门大学化学系，固体表面物理化学国家重点实验室Author's Address: State Key Laboratory Physical Chemistry of Solid Surface,Chemistry Department,Xiamen University,Xiamen 36100

A Unique Pharmacophore for Activation of the Nuclear Orphan Receptor Nur77 In vivo and In vitro

Nur77 is a steroid orphan receptor that plays a critical role in regulating proliferation, differentiation, and apoptosis, including acting as a switch for Bcl-2 function. We previously reported that the octaketide cytosporone B (Csn-B) is a natural agonist for Nur77. In this study, we synthesized a series of Csn-B analogues and performed a structure-activity analysis that suggested criteria for the development of a unique pharmacophore to activate Nur77. The components of the pharmacophore necessary for binding Nur77 included the benzene ring, the phenolic hydroxyl group, and the acyl chain of the Csn-B scaffold, whereas the key feature for activating the biological function of Nur77 was the ester group. Csn-B analogues that bound Nur77 tightly not only stimulated its transactivation activity but also initiated mitochondrial apoptosis by means of novel crosstalk between Nur77 and BRE, an antiapoptotic protein regulated at the transcriptional level. Notably, the derivative n-amyl 2-[3,5-dihydroxy-2-(1-nonanoyl)phenyl] acetate exhibited greater antitumor activity in vivo than its parent compounds, highlighting particular interest in this compound. Our findings describe a pathway for rational design of Csn-B-derived Nur77 agonists as a new class of potent and effective antitumor agents. Cancer Res; 70(9); 3628-37. (C) 2010 AACR.National Natural Science Fund of China [30630070, 20672089, 30921005]; Ministry of Science and Technology in China [2007CB914402, 2006AA09Z410]; Ministry of Education [706036]; Fujian Provincial Department of Science and Technology [2007Y0033]; Science Planning Program of Fujian Province [2009J1010]; Innovative Research Team in Science and Technology (University) in Fujian Provinc

Cytosporone B is an agonist for nuclear orphan receptor Nur77

Nuclear orphan receptor Nur77 has important roles in many biological processes. However, a physiological ligand for Nur77 has not been identified. Here, we report that the octaketide cytosporone B (Csn-B) is a naturally occurring agonist for Nur77. Csn-B specifically binds to the ligand-binding domain of Nur77 and stimulates Nur77-dependent transactivational activity towards target genes including Nr4a1 (Nur77) itself, which contains multiple consensus response elements allowing positive autoregulation in a Csn-B-dependent manner. Csn-B also elevates blood glucose levels in fasting C57 mice, an effect that is accompanied by induction of multiple genes involved in gluconeogenesis. These biological effects were not observed in Nur77-null (Nr4a1(-/-)) mice, which indicates that Csn-B regulates gluconeogenesis through Nur77. Moreover, Csn-B induced apoptosis and retarded xenograft tumor growth by inducing Nur77 expression, translocating Nur77 to mitochondria to cause cytochrome c release. Thus, Csn-B may represent a promising therapeutic drug for cancers and hypoglycemia, and it may also be useful as a reagent to increase understanding of Nur77 biological function.National Natural Science Fund of China [30630070, 30425014, 30325044]; Ministry of Science and Technology [2006CB503905, 2004CB518800, 2007CB914402]; Ministry of Education [706036, 306010, 705030