992 resultados para 282
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比较了具有单功能基团的共轭有机小分子噻吩和四氢噻吩对细胞色素c直接电化学反应的促进作用。发现四氢噻吩不能加速细胞色素c的直接电化学反应。而噻吩是一种很好的促进剂。表明噻吩分子中的共轭π键在加速细胞色素c的电子传递过程中起着重要作用。
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(eta(3)-C3H5)(2)CeCl5Mg2(tmed)(2) combined with HAl(i-Bu)(2) or Al(i-Bu)(3) can initiate the polymerization of isoprene with about 50% of the cis-1, 4 microstructure contained in the polymer. The insertion reaction of isoprene occurring between Ce3+ and e
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研究了聚[苯乙烯-甲基丙烯酸β(甲基亚硫酰基)乙酯](PSM)载体-三氯化钕(NaC13)络合物-Al(i-Bu)3体系催化丁二烯聚合的活性与PSM转化率和PSM·NdCl3络合物组成的关系。实验结果表明,PSM转化率为18.1%~53.4%,对PSM·NdCl3-Al(i-Bu)3体系的活性基本上无影响。低功能团含量的PSM·NdCl3络合物的活性优于高功能团含量的PSM·NdCl3。该络合物中Nd含量为4.5×10(-4)mol/g左右时,体系的催化活性最佳。体系的活性随引入的Lewis酸的种类和用量的不同而改变。
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A novel type of electrochemical detector based on a polyaniline-dispersed mercury-coated glassy carbon chemically modified electrode was investigated for the detection of monochloramine and dichloramine. A polyaniline dispersed-mercury modified electrode, which was prepared by coating polyaniline on a thin mercury film electrode using fast-sweep voltammetry, was developed. The selectivity could be altered using various counter ions incorporated into the polymer. The results indicated that the use of a conducting polymer-based electrochemical sensor for the selective determination of chloramine is a feasible approach.
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The C-H stretching, C-H bending, C-C stretching and the low-frequency vibration regions have been investigated by Raman spectroscopy for [n-CnH2n+1NH3]2 ZnCl4 with n=7 approximately 12, 16. It is found that their frequency and relative intensities are related to the length of carbon chain in the molecules and present the odd-even effect to carbon atom numbers in chain. Some changes in spectra are interpreted in terms of the different molecular packing and interaction of chain.
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用X-光电子能谱分析了Ru-Ti金属氧化物电极的组成、结构和元素价态。结果表明,电极表面不同于体内,讨论了表面和体内Ti的价态区别对Ru-Ti阳极活性和寿命的影响,指出掺杂Ir和Pd后会提高电极活性。
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测定了[n-C_nH_(2n+1)NH_3]ZnCl_4(n=7~12,16)配合物在碳氢伸缩、碳氢弯曲、碳碳伸缩和低频区的Raman光谱.发现它们的频率和相对强度与分子中烷基链的链长有关,并且表现出碳原子数的奇偶效应.从不同的分子堆积结构和分子间相互作用的角度讨论了光谱变化.
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英国Alcan公司从1986年开发了阳极氧化无机超滤膜,并专门为此成立了名为
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The free living conchocelis of Porphyra yezoensis Ueda was treated with N-methyl-N-nitro-N-nitrosoguanidine to induce pigmentation mutants. The artificial green pigmentation mutant of P. yezoensis conchocelis, which was composed entirely of green cells, was isolated through visualization with the unaided eye. The acquired green conchocelis was further developed into a green gametophytic blade. This mutant was relatively stable in color in both gametophytic blade and conchocelis phases. The gametophytic blade mutant was successively cultivated for commerce at some Porphyra farms in Rudong, China, and few wild type or sectorially variegated gametophytic blade occurred, indicating that the green mutant has commercial value. The green mutant was characterized as having lower phycoerythrin and higher phycocyanin content, and SDS-PAGE suggested that phycoerythrin was missing the gamma-subunit in comparison to the wild type. The wild type and the green mutant showed a clear difference in 02 evolution rates in white, green, yellow, and red light, which might be due to the qualitative and quantitative changes of phycoerythrin, and the quantitative difference of phycocyanin. (C) 2008 Elsevier B.V. All rights reserved.
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Seed rearing is an important part in large scale clam culture industry. Since the nutritional history affects early development in bivalve, the condition of larval nutrition plays a key role in successful seed rearing. So far, the molecular mechanism of nutrient uptake in bivalve larvae is unclear. As one of the important proteolytic enzymes, cathepsin B of several organisms has been reported to be involved in digestion. We intended to analyze whether cathepsin B is involved in larval nutrient metabolism in the economic bivalve, clam Meretrix meretrix. The full length of M. meretrix cathepsin B (MmeCB) cDNA was cloned, which is 1647 bp with an open reading frame of 1014 bp. The deduced amino acid sequence encoded a preproenzyme of 337 residues with Cys-114, His-282 and Asn-302 composing cathepsin B activity center. The temporal and spatial expressions of MmeCB mRNA were examined from trochophore to post larva stages by whole mount in situ hybridization. In trochophore stage, no detectable signal was found. In the later three stages, MmeCB mRNA was detected in the digestive gland, suggesting a possible role of MmeCB in digestion. Moreover, MmeCB mRNA was also observed in the epidermal cells in D-veligers. Cathepsin B specific inhibitor (CA074 methyl ester) was applied to block the activity of cathepsin B in unfed larvae. The average shell lengths of treated larvae were smaller than that in control groups. The results of mRNA epidermal distribution and inhibitor treatment in D-veligers indicated that MmeCB may be also associated with other pathway of nutrient metabolism in larval epidermis. The overall results in this paper revealed that MmeCB might play a role in larval nutrient metabolism. (C) 2008 Elsevier B.V. All rights reserved.
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本研究分为三个部分:1.以坛紫菜(Porphyra haitanesis Chang et Zheng)的叶状体和丝状体为研究对象,比较坛紫菜叶状体和丝状体的光合色素、色素蛋白的组成,并提取纯化藻红蛋白、藻蓝蛋白、藻胆体及类囊体膜和光系统。研究结果表明坛紫菜叶状体和丝状体色素及色素蛋白的含量不同,藻红蛋白是主要的色素蛋白,坛紫菜叶状体和丝状体的藻红蛋白的含量分别为2.9mg藻红蛋白/g鲜重、4.2mg藻红蛋白/g鲜重,这表明坛紫菜叶状体和丝状体藻红蛋白含量丰富,是提取藻红蛋白很好的材料。藻胆体的性质差异不大,但类囊体膜差异显著,从坛紫菜叶状体中分离到了两种不同的类囊体膜带,光系统Ⅰ(PSⅠ)和PSⅡ分别结合在两条类囊体膜带上,但从坛紫菜丝状体中也分离到两条类囊体膜带,它们的光谱性质和蛋白组成相似,仅放氧速率和DCIP活性有差异,从坛紫菜丝状体中我们仅分离到PSⅡ。坛紫菜叶状体PSⅡ有5种外在蛋白(33、20、Cytc 550、15、12kDa蛋白),而坛紫菜丝状体外在蛋白仅有4条,缺少12kDa蛋白。2. 以在中国江苏部分地区进行了大规模的商业化栽培的突变体条斑紫菜(Porphyra yezoensis Ueda)和野生型条斑紫菜为研究对象,比较其色素及色素蛋白组成、对不能光质的利用率及藻胆体的组成。条斑紫菜和突变型条斑紫菜对不同的光质利用效果有差异,在白光的照射下,野生型紫菜的放氧速率最大,而突变型紫菜在黄光照射下的放氧速率最大。条斑紫菜野生型与突变型色素含量上有明显的差异,突变型紫菜的藻红蛋白含量明显减少而藻蓝蛋白的含量增加。通过杂交的方法证实诱变所获得条斑紫菜突变体为细胞质突变,但是突变型紫菜却发生了由细胞核编码的γ亚基的缺失,这表明突变型紫菜藻红蛋白含量和性质发生了明显的变化。3. 为了找出淡水红藻-深紫美芒藻(Compsopogon coeruleus (Balbis) Montagne)分布狭窄及生物产量低的原因,本文对深紫美芒藻在不同的盐离子浓度下的放氧速率及藻胆体色素组成和结构上进行研究。结果显示:微量的NaCl(0.1mM)促进深紫美芒藻放氧,而深紫美芒藻在较高的NaCl(1、10mM), NaH2PO4 (0.1、1、10mM)和 NH4NO3(0.1、1、10mM)溶液中却没有检测到氧气的产生。这与深紫美芒藻生长的环境一致即深紫美芒藻生活在低盐浓度、低营养的泉水中。深紫美芒藻的藻胆体是由藻红蛋白、藻蓝蛋白及别藻蓝蛋白组成,上面结合α、β和γ亚基,含有藻红胆素、藻篮胆素,但缺乏缺少藻尿胆素。
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扇贝养殖是我国重要的海水养殖产业,然而自1997 年以来,养殖扇贝陆续爆发的大规模死亡,不但造成了巨大的经济损失,而且严重影响了该产业的健康发展。丝氨酸蛋白酶抑制因子及丝氨酸蛋白酶在无脊椎动物的免疫应答中起着核心作用,它们的协同作用直接导致外界病源入侵的信号转导和级联放大,并进一步激活一系列防御体系,如黑化反应、血液凝结和抗菌肽的合成等。因此,克隆扇贝参与免疫防御的丝氨酸蛋白酶抑制剂基因并对其功能进行研究,将有助于进一步研究扇贝的免疫防御机制,丰富和发展无脊椎动物免疫学的内容。 运用大规模EST技术和RACE技术从栉孔扇贝中克隆出一个Kazal型丝氨酸蛋白酶抑制剂基因,定名为CfKZSPI。该基因cDNA序列全长1788bp,其中5' 非编码区(Untranslated Region, UTR)为97 bp,3' UTR161 bp,有一个典型的多聚腺苷酸信号序列(AATAAA)和一个ploy A 尾巴,开放阅读框(Open Reading Frame, ORF)含有1530 bp,编码509 个氨基酸残基。对其推测氨基酸序列进行分析,发现其中包括22个氨基酸残基组成的信号肽序列和12个Kazal型丝氨酸蛋白酶抑制剂结构域。采用QRT-PCR(quantitative real time PCR)对鳗弧菌浸泡刺激后栉孔扇贝血淋巴中CfKZSPI 的 mRNA表达量进行了检测,发现其mRNA 的表达量在鳗弧菌刺激后3h明显上升,达到空白组的43.6倍;然后在6h时有所下降,为空白组的15.0倍;随着菌刺激时间的增长,CfKZSPI基因的 mRNA 表达量急剧增加,在刺激后8h,12h,24h分别达到空白组的174.1,207.8,675.4倍。统计分析发现3h(P=0.019<0.05)和12h(P=0.020<0.05)时,CfKZSPI基因mRNA表达量与空白组差异均显著。为了研究栉孔扇贝CfKZSPI的蛋白活性,将其第十二个结构域克隆到pET-32a(+)载体中,转化大肠杆菌Rosetta-gami(DE3)表达菌株,获得可溶性表达的蛋白rCfKZSPI-12,对其进行抑制蛋白酶活性的分析,发现其对胰蛋白酶有很强的抑制活性,而对凝血酶没有抑制活性。当rCfKZSPI-12与胰蛋白酶分子比率为1:1时,约90%的蛋白酶活性被抑制。运用狄更斯作图法研究rCfKZSPI-12对胰蛋白酶的抑制能力,结果发现其对胰蛋白酶的抑制常数为173 nmol L-1。 采用同样方法从海湾扇贝cDNA文库中克隆出一个Kunitz型丝氨酸蛋白酶抑制剂基因,定名为Aikunitz。该基因全长632 bp,其中5' UTR 为105 bp,3' UTR 为 245 bp,有一个典型的多聚腺苷酸信号序列(AATAAA)和一个ploy A 尾巴,ORF 含有282 bp,编码93 个氨基酸残基。推测的氨基酸序列N末端有一个20个氨基酸残基组成的信号肽序列,成熟蛋白包括一个Kunitz型丝氨酸蛋白酶抑制剂结构域。采用QRT-PCR对鳗弧菌和藤黄微球菌感染后海湾扇贝血淋巴中Aikunitz 的mRNA的表达量进行了检测,结果发现其在鳗弧菌刺激后3h到9h持续上升,9h时表达量为PBS对照组的4.49倍(P=0.008<0.05),然后开始下降,在72h时表达量为对照组的0.24倍(P=0.021<0.05);而在藤黄微球菌刺激后3h到12h其表达量上升,其中6h时为空白组的5.95倍(P=0.0004<0.01);12h以后迅速下降,其中24h的表达量为对照组的0.38倍(P=0.028<0.05)。将Aikunitz基因编码的成熟蛋白按照重组CfKZSPI-12的方法进行重组表达,并对重组蛋白进行抑制蛋白酶和抑菌活性分析。结果发现其对胰蛋白酶和弹性蛋白酶两种丝氨酸蛋白酶都没有抑制作用。抑菌实验同样发现,重组Aikunitz 对供试的革兰氏阳性菌藤黄微球菌和革兰氏阴性菌鳗弧菌和大肠杆菌都不显示明显抑菌活性。
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To investigate the antitumor effect of bromophenol derivatives in vitro and Leathesia nana extract in vivo, six bromophenol derivatives 6-(2,3-dibromo-4,5-dihydroxybenzyl)-2,3-dibromo-4,5-dihydroxy benzyl methyl ether (1), (+)-3-(2,3-dibromo-4,5-dihydroxyphenyl)-4-bromo-5,6-dihydroxy-1,3-dihydroisobenzofuran (2), 3-bromo-4-(2,3-dibromo-4,5-dihydroxybenzyl)-5-methoxymethyl-pyrocatechol (3), 2,2',3,3'-tetrabromo-4,4',5,5'-tetrahydroxy-diphenylmethane (4), bis(2,3-dibromo-4,5-dihydroxybenzyl) ether (5), 2,2',3-tribromo-3',4,4',5-tetrahydroxy-6'-ethyloxymethyldiphenylmethane (6) were isolated from brown alga Leathesia nana, and their cytotoxicity were tested by MTT assays in human cancer cell lines A549, BGC-823, MCF-7, B16-BL6, HT-1080, A2780, Bel7402 and HCT-8. Their inhibitory activity against protein tyrosine kinase (PTK) with over-expression of c-kit was analyzed also by ELISA. The antitumor activity of ethanolic extraction of Leathesia nana (EELN) was evaluated on S-180-bearing mice. All compounds showed very potent cytotoxicity against all of the eight cancer cell lines with IC50 below 10 mu g/mL. In PTK inhibition study, all bromophenol derivatives showed moderate inhibitory activity and compounds 2, 5 and 6 showed significant bioactivity with the inhibition ratio of 77.5%, 80.1% and 71.4%, respectively. Pharmacological studies reveal that EELN could inhibit the growth of Sarcoma 180 tumor and increase the indices of thymus and spleen to improve the immune system remarkably in vivo. Results indicated that the bromophenol derivatives and EELN can be used as potent antitumor agents for PTK over-expression of c-kit and considered in a new therapeutic strategy for treatment of cancer.
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目的 建立了反相高效液相色谱法同时测定藏木香中土木香内酯和异土木香内酯的方法.方法 采用Phenomenex Kromasil C18色谱柱(4.6mm×250mm,5.0μm);流动相为乙腈-0.04%磷酸溶液(50:50);检测波长:194 nm;流速:1.0 mL•min~(-1).结果 异构体土木香内酯和异土木香内酯达到基线分离,含量测定的线性良好,线性范围和相关系数分别为0.07~4.80μg•L~(-1) (r=0.999 8),0.07~4.85μg•L~(-1) (r=0.999 8);回收率分别为97.5%和102.1%;方法精密度良好,RSD分别为1.56%和1.87%(n=5);方法重现性良好,RSD分别为1.67%和0.92%(n=5).结论 所建立的方法简便、快捷、准确,重现性好,可用于藏木香药材及其制剂的质量控制.