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1.
硒蛋白的抗氧化性研究与第21个氨基酸的发现 总被引:7,自引:0,他引:7
硒是人体必需的微量元素,以硒代半胱氨酸(Sec)的形式存在于蛋白质中作为硒酶的活性中心发挥作用,其生物功能主要是抗氧化。由于硒与人体健康具有十分密切的关系,所以硒蛋白的研究有着重要的理论和实际意义。本文以第一个硒蛋白细胞谷胱甘肽过氧化物酶为例,结合作者自己的工作,重点对该硒酶的结构、催化机制和模拟进行了综述,并就TGA编码Sec致第21个氨基酸的发现以及基于硒代半胱氨酸插入元件(SECIS)的特征寻找新硒蛋白的研究进展进行了介绍。 相似文献
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基因组中硒蛋白的信息学 总被引:4,自引:0,他引:4
人类已经步入"后基因组"时代,基因组研究的重心将由测定基因的DNA序列转移到解释生命的所有遗传信息,从分子整体水平对生物学功能的研究,在分子层面上探索人类健康和疾病的奥秘.硒蛋白基因是各种基因组中一类重要的蛋白质基因,从基因组中寻找新的硒蛋白基因,对于硒蛋白生物功能的探索具有十分重要的意义.本文就硒代半胱氨酸插入元件(SECIS)结构特征、从基因组中寻找硒蛋白的生物信息学方法及其研究进展作了简要介绍,并对未来的发展趋势进行了展望. 相似文献
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蛋氨酸(Met)是生物体内很容易被氧化的氨基酸之一,氧化应激条件下,生成S型和R型蛋氨酸亚砜(MetO), 晶状体蛋白中MetO的增加与晶状体老化和白内障形成相关。生物体内存在着两种不同的蛋氨酸亚砜还原酶(Msr),即MsrA和B,分别能特异性地作用于自由或结合在蛋白质中的S-MetO和R-MetO,将MetO修复为Met,从而避免了蛋白质结构和功能的改变。在哺乳动物中,MsrA以单基因形式存在,而MsrB有3种异构体,分别为MsrB1,MsrB2和MsrB3,其中MsrB1是一个硒蛋白,又被称为硒蛋白R(SelR)。本文介绍了Msrs的基因表达、分布和亚细胞定位,比较了MsrA和MsrBs蛋白结构和催化机制的异同,讨论了晶状体蛋白Met残基的氧化与白内障形成和发展的关系。现有的这些研究结果表明Msrs作为一类特异性的抗氧化还原酶,通过对MetO的修复,在抑制晶状体的损伤方面发挥重要作用。此外,MsrB1作为一个硒蛋白受机体硒水平的调节,因此,通过补硒保持晶状体适当的硒浓度以维持MsrB1的活性,对白内障的形成和发展可能具有一定的预防作用。 相似文献
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高效液相色谱-等离子体质谱联用方法研究富硒大米中硒的形态 总被引:3,自引:0,他引:3
根据Osborne溶解性蛋白质分类法,用去离子水、2%NaCl溶液、70%乙醇、0.5%KOH4种溶液分别提取出大米中相应的清蛋白、球蛋白、醇溶蛋白及谷蛋白。利用电感耦合等离子质谱(ICP-MS)测量各类蛋白提取液中的硒含量;用色谱与质谱联用法对大米蛋白提取液中含硒蛋白组分及含硒氨基酸组成进行初步分析。结果表明:大米中的硒主要与蛋白质结合,在4类蛋白提取液中硒含量由高到低的分布顺序为:谷蛋白、醇溶蛋白、清蛋白和球蛋白。清蛋白提取液中,分子量为12.6 kDa蛋白是主要的含硒蛋白组分;大米中约30%的硒以硒代半胱氨酸形式存在。 相似文献
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硒是哺乳动物必需的一种微量营养元素,主要以硒代半胱氨酸的形式存在于各种硒蛋白中,硒的主要生物功能通过硒蛋白实现.在25种哺乳动物硒蛋白中,有7种硒蛋白位于内质网,分别为2型脱碘酶、15-kDa硒蛋白、硒蛋白M、硒蛋白T、硒蛋白K、硒蛋白S和硒蛋白N.除了2型脱碘酶外,对其余内质网硒蛋白知之甚少.最近一些研究显示,一些内质网硒蛋白在氧化还原平衡调节、蛋白质折叠质量控制、错误折叠蛋白从内质网逆向转运至胞质、Ca2+稳态调节、内质网应激调节及炎症调节等过程中发挥作用.本文介绍了每种内质网硒蛋白的结构、功能及其生理和病理作用的一些最新研究进展,并对未来需要研究的内容进行了展望. 相似文献
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硒蛋白的分子生物学及与疾病的关系* 总被引:3,自引:0,他引:3
硒蛋白是微量元素硒在体内存在和发挥生物功能的主要形式。因硒蛋白的活性中心硒代半胱氨酸由传统终止码TGA编码,故从基因组中预测硒蛋白以及用基因工程技术表达硒蛋白均很困难。有关硒抗氧化、对癌症、神经退行性疾病和病毒作用的报导较多,但结论并不一致。本文综述了硒蛋白基因预测、蛋白质表达调控以及硒和硒蛋白对癌症、神经退行性疾病和病毒的作用及机制等方面的近期进展,研究提高硒蛋白生物信息学预测准确率和基因工程表达量的方法,分析了解硒蛋白与疾病发生发展的关系和机制,探索不同硒蛋白作为预防药物开发、作为癌症治疗和药物筛选靶标的可能性。 相似文献
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蛋白质蛋氨酸亚砜化是一种重要的氧化还原依赖的蛋白质翻译后修饰,不仅是氧化应激的重要标志物之一,也是一种蛋白质功能调控开关可影响活性氧信号转导,与一系列疾病尤其是神经退行性疾病的发生发展密切相关。 在许多生物体中,蛋氨酸亚砜还原酶是目前已经发现的唯一能将蛋白质蛋氨酸亚砜还原为蛋氨酸的物质,可以修复氧化损伤蛋白,恢复蛋白质功能,调控细胞氧还平衡,对相关疾病的治疗具有非常重要的意义。 本文重点介绍蛋氨酸亚砜和蛋氨酸亚砜还原酶的结构和催化机理,综述蛋氨酸亚砜和蛋氨酸亚砜还原酶荧光探针的部分研究进展,对该领域的研究前景进行展望。 相似文献
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用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%. 相似文献
12.
Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives. 相似文献
13.
The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion. 相似文献
14.
Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments. 相似文献
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N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%). 相似文献
16.
Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones. 相似文献
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The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula. 相似文献
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In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates. 相似文献
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KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields. 相似文献
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Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines. 相似文献