929 resultados para LC-MS


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采用对掺入La_2O_3的石墨棒原位活化并结合交换电极回放方法制备了产率较高的金属富勒烯,并用甲苯高温热提取的方法有效地提取出La@C_(2n),其中La@C_(74)为可溶性金属富勒烯增加了新成员.同时,首次采用解吸电子轰击质谱对提取物进行了表征,讨论了提取物的ESR谱.

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本文应用色谱—质谱(GS/MS)及裂解色谱质谱(Py/GC/MS)研究了二甲基乙氧基乙烯基硅烷(VDMES)等离子体聚合的气体冷凝物及聚合物膜。鉴别出多种化合物,并推导了等离子体聚合的反应历程,进而得到了气相反应与表面反应的实验依据。

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This paper reports the results of the crystal and molecular structures, CI-MS and FAB-MS analyse of Cl3GeCH2CH2COOH and Cl3GeCH(CH3)CH2COOH. The characters and active parts of these molecules are also discussed

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Hypoxia, as one suboptimal environmental condition, can affect the physiological state of shrimp during pond aquaculture. To better understand the mechanism of response to hypoxic stress in Chinese shrimp Fenneropenaeus chinensis, proteome research approach was utilized. Differentially expressed proteins of hepatopancreas in adult Chinese shrimp between the control and hypoxia-stressed groups were screened. By 2-DE analysis, 67 spots showed obvious changes after hypoxia. Using LC-ESI-MS/MS, 51 spots representing 33 proteins were identified including preamylase, arginine kinase, phosphopyruvate hydratase, citrate synthase, ATP synthase alpha subunit, chymotrypsin BI, chitinase, ferritin, C-type lectin receptors, transketolase, formylglutathione hydrolase, formyltetrahydrofolate dehydrogenase, aldehyde dehydrogenase, glutathione peroxidase, cytosolic manganese superoxide dismutase, protein disulfide isomerase, beta-actin, oncoprotem nm23, crustacyanin-Cl and so on. These proteins could be functionally classified into several groups such as proteins related to energy production, metabolism-related proteins, immune-related proteins, antioxidant proteins, chaperones, cytoskeleton proteins and ungrouped proteins. The transcription levels of ten selected genes encode the identified proteins were analyzed by real-time PCR at different sampling times of hypoxia. This study is the first analysis of differentially expressed proteins in the hepatopancreas of shrimp after hypoxia and provides a new insight for further study in hypoxic stress response of shrimp at the protein level.

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C-phycocyanin was purified on a large scale by a combination of expanded bed adsorption, anion-exchange chromatography and hydroxyapatite chromatography from inferior Spirulina platensis that cannot be used for human consumption. First, phycobiliproteins were extracted by a simple, scaleable method and then were recovered by Phenyl-Sepharose chromatography in an expanded bed column. The purity (the A(620)/A(280) ratio) of C-phycocyanin isolated with STREAMLINE (TM) Column was up to 2.87, and the yield was as high as 31 mg/g of dried S. platensis. After the first step, we used conventional anion-exchange chromatography for the purification steps, with a yield of 7.7 mg/g of dried S. platensis at a purity greater than 3.2 and with an A(620)/A(650) index higher than 5.0. The fractions from anion-exchange chromatography with a level of purity that did not conform to the above standard were subjected to hydroxyapatite chromatography, with a C-PC yield of 4.45 mg/g of dried S. platensis with a purity greater than 3.2. The protein from both purification methods showed one absolute absorption peak at 620 nm and a fluorescence maximum at 650 nm, which is consistent with the typical spectrum of C-phycocyanin. SDS-PAGE gave two bands corresponding to 21 and 18 kDa. In-gel digestion and LC-ESI-MS showed that the protein is C-phycocyanin. (c) 2006 Elsevier B.V. All rights reserved.

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Peroxiredoxin (Prx) is known to be an antioxidant protein that protects the organisms against various oxidative stresses and functions in intracellular signal transduction. A Prx gene was firstly isolated in the crustacean, Chinese shrimp Fenneropenaeus chinensis. The full-length cDNA consists of 942 bp with a 594 bp open reading frame, encoding 198 amino acids. The molecular mass of the deduced amino acid is 22041.17 Da with an estimated pI of 5.17. Sequence comparison showed that Prx of F. chinensis shares 76%, 73% and 72% identity with that of Aedes aegypti, Branchiostoma belcheri tsingtaunese and Drosophila melanogaster, respectively. Northern blot analysis revealed the presence of Prx transcripts of F chinensis in all tissues examined. Real-time PCR analysis indicated that the Prx showed different expression profiles in shrimp hemocytes and hepatopancreas after artificial infection with Vibrio anguillarum. In addition, a fusion protein containing Prx was produced in vitro. LC-ESI-MS analysis showed that four peptide fragments of the recombinant protein were identical to the corresponding sequence of F. chinensis Prx. And the purified recombinant proteins were shown to reduce H2O2 in the presence of dithiothreitol. (c) 2007 Elsevier Ltd. All rights reserved.

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Manganese superoxide dismutase (MnSOD) plays an important role in crustacean immune defense reaction by eliminating oxidative stress. Knowledge on MnSOD at molecular level allows us to understand its regulatory mechanism in crustacean immune system. A novel mitochondrial manganese superoxide dismutase (mMnSOD) was cloned from hepatopancreas of Chinese shrimp Fenneropenaeus chinensis by 3' and 5' rapid amplification of cDNA ends (RACE) PCR. The full-length cDNA consists of 1185 bp with a 660 bp open reading frame, encoding 220 amino acids. The deduced amino acid sequence contains a putative signal peptide of 20 amino acids. Sequence comparison showed that the mMnSOD of F. chinensis shares 88% and 82% identity with that of giant freshwater prawn Macrobrachium rosenbergii and blue crab Callinectes sapidus, respectively. mMnSOD transcripts were detected in hepatopancreas, hemocytes, lymphoid organ, intestine, ovary, muscle and gill by Northern blotting. RT-PCR analysis indicated that mMnSOD showed different expression profiles in shrimp hemocytes and hepatopancreas after artificial infection with while spot syndrome virus (WSSV). In addition, a fusion protein containing mMnSOD was produced in vitro. LC-ESI-MS analysis showed that two peptide fragments (-GDVNTVISLAPALK- and -NVRPDYVNAIWK-) of the recombinant protein were identical to the corresponding sequence of M. rosenbergii mMnSOD, and the enzyme activity of the refolded recombinant protein was also measured. (c) 2006 Elsevier Ltd. All rights reserved.

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Ferritin, the iron storage protein, plays a key role in iron metabolism. A cDNA encoding ferritin (FcFer) was cloned from hepatopancreas of Chinese shrimp, Fenneropenaeus chinensis. The predicted protein contains 170 amino acid residues with a predicted molecular weight (MW) about 19, 422.89 Da and theoretical isoelectric point (PI) of 4.73. Amino acid alignment of FcFer revealed 97% homology with Litopenaeus vannamei ferritin. Results of the RT-PCR showed that the expression of FcFer mRNA was up-regulated after shrimp was challenged with either white spot syndrome virus (WSSV) or heavy metal ions (Zn2+ and Cu2+) in the laboratory. A fusion protein containing FcFer was produced and the purified recombinant protein exhibited similar function of iron uptake in vitro. The result of in-gel digestion and identification using LC-ESI-MS showed that two peptide fragments (-DDVALPGFAK- and -LLEDEYLEEQVDS1KK-) of the recombinant protein were identical to the corresponding sequence of L. vannamei ferritin. The recombinant FcFer protein will be proved useful for study on the structure and function of ferritin in F chinensis. (c) 2006 Elsevier B.V. All rights reserved.

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An off-line chelation system combined with ICP-MS technique was developed for the quantitative determination of trace elements in seawater, namely V, Co, Ni, Cu, Zn, Mo, Cd, Pb, U and rare earth elements(REEs). The system was built based on an ion chromatography equipped with MetPac((R)) CC-I chelation columns which had a strong selective chelation to these target elements within a pH range 5.2-5.6. Acidified seawater samples and NH4Ac(2 mol/L) were blended to meet suitable pH before being injected into the chelation column, thus target elements were retained while alkali and alkaline metals were excluded. Then chelated elements were eluted by HNO3 (1 mol/L) and samples were collected for ICP-MS analysis. Varying the ratio of input( gen. 200 mL) to output( gen. 5 mL), the target elements which were concentrated as 40 times as their concentrations were far beyond instrumental quantification limits. At last, a certificated seawater CASS-4 was introduced and our detected values were in good agreement with those certified values.

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使用膨化柱和离子交换或羟基磷灰石柱层析相结合的方法,分别从多管藻、坛紫菜及钝顶螺旋藻中分离纯化了R-藻红蛋白溶液和C-藻蓝蛋白。光谱检测及电泳分析结果证明完全符合经典的藻胆蛋白纯度标准。彭化床最突出的优点是克服了常规分离方法堵塞色谱柱的难题,纯化速度快、产量高、不需要常规色谱方法所要求的填料的平衡及粗提液的预处理,仅需一步操作就可以得到满足一般食品添加剂纯度要求的藻胆蛋白,极大地简化了后续的纯化程序,减少了分离纯化的步骤和时间,而其产率及纯度均高于常规的藻胆蛋白分离方法。这同时也降低了藻胆蛋白分离纯化的成本。 本文通过戊二醛或环氧氯丙烷交联的方法,合成了四种壳聚糖-氨基酸共聚小球。并选取吸附性好的戊二醛交联孔球和戊二醛交联微球系统测定了其对R-藻红蛋白和C-藻蓝蛋白的吸附和缓释性能。 纯化了藓羽藻中与其细胞器团聚密切相关的一种凝集素并进行了部分性质的鉴定。N端前15个氨基酸序列及LC-ESI-MS质谱分析结果证明此凝集素属于一种新的蛋白质族。实验证明,凝血活性与细胞器团聚活性并不完全依赖于此凝集素分子相同的结构域。 通过异双功能试剂SPDP处理藓羽藻凝集素使之衍生化,DTT处理R-PE在其分子内引入外源巯基,然后将活化的R-藻红蛋白与凝集素进行交联反应。交联产物经凝胶过滤纯化并检测,但电泳及荧光显微镜检测结果并不能证明交联探针的成功制备。

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卤虫(Artemia)是一种广温、耐高盐的小型甲壳动物,广泛分布于内陆盐湖和沿海盐田中。卤虫的无节幼体作为重要的蛋白优质饵料,被广泛的应用于水产养殖生产。卤虫具有特殊的生物学特性,是研究甲壳动物胚胎发育的良好的实验材料,同时也是一种研究动物抗逆机制的模式动物。卤虫有卵生和卵胎生两种繁殖后代的方式,当环境条件适宜时,卤虫倾向于采取卵胎生方式,即直接产生无节幼体;而在恶劣的环境条件下,卵生方式占主要地位,产生处于滞育状态的、具有复杂外壳的休眠卵。卤虫的滞育卵具有独特的生物学特性和特殊的生理生化特点。其发育停滞,细胞分裂停止,酶活力下降,代谢活动受到抑制并可耐受各种极端恶劣环境,如缺氧、低温、紫外线、干燥等。即使在最适的环境中滞育卵的孵化率也很低,只有受到某些特定的非生物信号的刺激才自能终止这种滞育状态,恢复生理代谢;当环境条件适宜时,能够继续发育孵化成无节幼体。因此,卤虫的滞育卵在卤虫的整个生活史中占有重要的地位。另一方面,卤虫是极端环境生物,能够抵抗各种恶劣环境胁迫刺激,因此是研究抗逆机理的良好的实验动物。 本论文利用蛋白质组学技术,研究了卤虫滞育卵及滞育卵发育过程中的蛋白质组表达情况,并研究了卤虫幼体在重金属刺激后蛋白表达的变化情况。得到如下结果: 建立了中华卤虫滞育卵可溶性总蛋白的双向凝胶电泳对照图谱。在pH 4–7、分子量10-100 kDa范围内,检测到约 233个蛋白点,并利用高效液相色谱-质谱联用(LC-ESI-MS/MS)技术鉴定了其中的48个丰度较大及感兴趣的蛋白点,根据这些蛋白的生物学功能进行分类,功能类别包括细胞防御蛋白、抗氧化蛋白、细胞骨架蛋白、代谢相关蛋白等。在卤虫滞育卵中共分离鉴定到6个分子量和等电点存在差异的小热休克蛋白p26的异构体,生物信息学分析表明该蛋白有三种不同的功能位点,分别是蛋白激酶C磷酸化位点,Casein 激酶II磷酸化位点及 N-myristoylation 位点。 采用低温脱水的方法对滞育卵进行激活刺激,并对活化卵和滞育卵蛋白表达图谱进行了对比分析。结果表明对卤虫滞育卵的激活刺激引起了其蛋白表达的明显变化。活化卵图谱中蛋白点总数比滞育卵中明显增多,特别是在pI<5.5范围内。约70个蛋白点在激活刺激后上调表达,包括部分只在激活卵中表达的蛋白;25个下调表达,包括部分只在滞育卵中表达的蛋白;其余约60%(占滞育卵蛋白点数目百分比)的蛋白点表达量基本恒定。热休克蛋白家族、抗氧化蛋白家族成员等蛋白变化明显,小热休克蛋白p26、小热休克蛋白ArHsp21蛋白以及过氧化物还原酶异构体在激活卵中特异表达。 活化卵孵化过程中不同发育时期的蛋白表达又呈现出不同的特点,分别在孵化后6h、12h、18h和24h的蛋白质组学图谱上检测到267、285、195和210个蛋白点。孵化后6h和12h休眠卵蛋白表达个数相对较多,与胚胎发育过程中的器官发生和剧烈的形态变化相适应;孵化后18h和24h休眠卵蛋白表达明显下降,部分蛋白的表达关闭,部分蛋白开始富集表达。 利用双向凝胶电泳技术分析了中华卤虫幼体受到急性硫酸铜刺激后的蛋白表达变化情况。通过图谱对比分析,检测到了5mM硫酸铜刺激24h后,卤虫幼体中14个差异表达的蛋白点。利用LC-ESI-MS/MS技术鉴定了其中的7个蛋白,其中3个蛋白上调表达,分别是热休克蛋白70(7.5倍), 肌动蛋白(2.3倍)和伴侣分子亚基1(3.0倍)。3个蛋白下调表达,分别是:精氨酸激酶(2.8倍), 延伸因子2 (2.0倍) 和富含甘氨酸蛋白(2.0倍)。硫酸铜刺激后特异表达的一个蛋白被鉴定为过氧化物还原酶(Peroxiredoxin,Prx)。根据质谱检测提供的蛋白肽段信息和其他生物过氧化物还原酶保守氨基酸序列设计简并引物,结合RACE技术,从中华卤虫幼体中克隆到了过氧化物还原酶基因,该基因的cDNA全长为756个碱基,其中开放阅读框为594个碱基,编码198个氨基酸,其蛋白理论分子量为22.0 kDa,理论等电点为6.98。多序列比对结果显示中华卤虫Prx基因的推导氨基酸序列与美国卤虫和中国对虾的同源性高达98%和94%。实时荧光定量PCR结果显示,硫酸铜刺激后,该基因在卤虫无节幼体中的转录水平明显升高,在24h达到正常水平的3.0倍。

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有机锡化合物被广泛用作塑料制品中的稳定剂、船舶油漆的防污剂、工业催化剂、农林业杀虫杀菌剂以及用于木材的防腐保存等,已经引起严重的环境污染。世界上许多国家纷纷制定相应的法规对其使用加以禁止或限制。我国目前还没有明确的限制有机锡使用的法律法规,缺少有机锡污染的第一手资料,更没有长期的控制、监测与研究计划。由于有机锡的种类繁多,理化性质存在差别,所以在提取、分离和测定中均存在较大的困难。从我国这方面己有的工作来看,缺乏各种高选择性的分离方法和高灵敏度的检测方法是制约这项研究广泛开展的原因之一。有机锡的痕量与超痕量分析技术是当今环境和食品安全分析领域的前沿技术。 本论文利用高效液相色谱和电感耦合等离子体质谱联用技术建立了海洋环境中多种有机化合物的同时快速检测方法;发展了多种海洋环境样品中有机锡的前处理技术;研究了有机锡在海洋生物中的分布、代谢及降解过程中化学形态的变化;同时发展了海洋环境中多种痕量元素的快速检测方法。所建立的高效液相色谱和电感耦合等离子体质谱联用技术可同时、快速分析5种有机锡的形态(三甲基锡TMT、二苯基锡DPhT、二丁基锡DBT、三丁基锡TBT和三苯基锡TPhT),其检出限均低于0.3μg/L。 用所建立方法对南海海洋生物样品中的有机锡污染进行了研究,利用SPSS软件对检测结果进行了探讨,发现在所研究海洋生物样品的97.2%中可检出丁基锡和苯基锡化合物,其浓度分布处于该化合物检出限~1487.8ng/g范围内。其中,贝类样品中总有机锡的平均浓度为416.9ng/g,远远高于鱼类样品中总有机锡的平均浓度(211.9ng/g)。海洋生物中存在高浓度的有机锡说明本海域有机锡污染严重,已经对生态环境造成了严重影响,危害到人类生活。其主要的污染源是防污涂料的应用,目前紧迫的问题是采取必要的措施来控制有机锡的使用。 本工作建立了海水样品和沉积物样品中五种有机锡的简单快速萃取方法。采用加入2%的环庚三烯酚(tropolone)的二氯甲烷CH2Cl2对海水中的有机锡进行萃取,大大提高了有机锡的萃取率,减少了萃取的时间,二苯基锡(DPhT)、二丁基锡(DBT)、三丁基锡(TBT)和三苯基锡(TPhT)的萃取率均在80%以上,仅三甲基锡(TMT)的萃取率较低(在50%左右),究其原因,可能是因为在萃取的过程中三甲基锡(TMT)产生了降解。采用流动相和0.2%环庚三烯酚酮(tropolone)对沉积物国际标准物质PACS-2进行超声萃取及高速离心后,用所建方法进行了分析。结果表明,测定值与标准值吻合。研究表明,所建立的方法可用于实际环境沉积物中有机锡的形态分析。 本文建立了流动注射与电感耦合等离子体质谱联用技术直接同时测定海水中多种痕量元素的方法。该方法采用痕量进样技术,能够有效地减少海水中Na,Mg, Ca和Cl等大量基体元素对待测痕量元素测定的干扰,减少这些元素在电感耦合等离子体采样锥上的盐沉积,可以同时测量海水中的V、Cr、Mn、Fe、Co、Ni、Cu、Zn、As、Mo、Cd、Pb,Hg和U等痕量级元素。用所建的方法测定南海海域海水中的重金属元素,发现Cd,Cr,As等有毒有害元素的污染很轻,均符合Ⅰ级海水的限量。 在海洋沉积物样品处理研究中,本工作改进了不需要赶走HF酸就可以对沉积物消解完全的密闭容器消解法,由于减少了赶走HF酸的步骤,使消解的时间由原来的二十个小时降低为十个小时,大大降低了消解的时间。采用该样品消解方法,并用ICP-MS测定了南黄海海域沉积物中锡及其他重金属元素的含量。建立了微波消解-ICP-MS测定海洋生物中锡、砷、镉、汞及铅等有害重金属元素的分析方法,并用于南黄海7个及南海海域29个海产品中的测定。测定结果表明海洋生物中上述有毒有害元素有不同程度的超标问题;不同种类,不同产地的海洋生物中重金属元素的含量有一定的差别,这些研究结果为海产品安全质量控制提供了有价值的科学信息。 在上述各章工作的基础上,本文研究了有机锡在海洋生物中的分布、代谢及降解过程,并初步建立了高效液相-电喷雾-飞行时间质谱(LC-APCI-TOF-MS)测定有机锡的方法,可对未知的有机锡化合物进行结构表征。有机锡在贝类中不同的组织显示,其内脏中有机锡的含量高于肌肉中有机锡含量。常规的煮、炸、蒸及微波的烹饪方式并不能降解海产品中的有机锡化合物。

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[目的]基于气相色谱-质谱(GC-MS)法测定藏木香栽培品种挥发油的化学成分。[方法]采用水蒸气蒸馏法从藏木香栽培品种中提取挥发油,并用GC-MS联用仪对其挥发油的化学成分进行研究。[结果]分离并确认了37种成分,其主要成分是桉叶油二烯5,11(13)-内酯-8,12,异-榄香烯,异-喇叭烯,桉叶油二烯4,11(13)-内酯-8,12。[结论]分析获得的主要化学成分及其功效为藏木香这一天然药用植物资源的人工规范化栽培和进一步综合开发利用提供了科学依据。

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目的:分析治疗胃病常用的藏成药帕朱胶囊(寒水石,诃子,石榴子,胡椒,荜拔等)的主要化学成分。方法:采用超临界CO_2萃取方法提取帕朱胶囊的可溶性成分,并用气相色谱-质谱联用法对提取部位进行化学成分分析,峰面积归一化法计算各组分的相对含量。结果:共分离鉴定了22种化合物,主要成分含量为胡椒碱44.2%、亚油酸21.1%、甲基-甲撑基奥-异丙烯内酯10.5%、棕榈酸4.8%和γ-羟基-榄香烯酸内酯3.5%等。结论:藏药帕朱胶囊的主要化学成分为胡椒碱和亚油酸,两者含量共占全部提取物的65.3%

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目的:用新方法提取藏药材石榴籽油,并对其进行化学成分分析,为石榴籽的药理研究和应用提供实验依据。方法:采用超临界CO_2萃取方法提取石榴籽的可溶性成分,并用气相色谱-质谱联用法对提取部位进行化学成分分析,峰面积归一化法计算各组分的相对含量。结果:共分离鉴定了10种化合物,主要成分含量为亚油酸40.0%、油酸22.7%、棕榈酸17.5%、硬脂酸9.0%及共轭亚油酸5.7%。结论:藏药材石榴籽的主要化学成分为亚油酸和油酸,两者含量共占全部提取物的62.7%。