共查询到20条相似文献,搜索用时 125 毫秒
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本文用莰烯经Vilsmeier-Haack甲酰化反应制得的E型ω-甲酰基莰烯为原料,在草酸催化下使之与乙二硫醇缩醛化,再使所得的硫代缩醛在镍催化下发生氢解而合成了E型ω-甲基茨烯,提出了合成ω-甲基茨烯的一种新方法.所合成的硫代缩醛和ω-甲基莰烯均进行了纯化和质谱、红外和核磁共振等分析. 相似文献
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以香叶醇为原料经过4步反应得到8-溴-3,7-二甲基-(2E,6E)-辛二烯基苯硫醚(7),(7)与(?)牛儿醛在Cr(Ⅱ)作用下立体选择地得到苏式-7-羟基-3,9,13-三甲基-6-异丙烯基-(2E,8E,12)-十四碳三烯苯硫醚. 相似文献
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管延勇 《曲阜师范大学学报》1991,17(2):110-110,112
本文定义并讨论了比文献〔1〕中的E—矩形性拟正则半群更广的一类半群,即E—矩形周期半群,并给出了幂等元集是带的周期半群能E—矩形分解的条件。定义若周期半群S的幂等元集是带且是矩形带,则称S是E—矩形周期半群。设S是周期半群,记S_m={α∈S|α的指数是1},则S_m Regs(S的正则元集)。定理1 若S是E—矩形周期半群,则RegS=S_m且它是S的子半群。定理2 若s是E—矩形周期半群,则α∈S,或者J_a={a}或者α∈S_m。命题1 设S是E—矩形周期半群,则S的格林关系分类图表如下: 相似文献
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从一株南海红树林真菌E33号中分离到一个新的水杨酸衍生物,命名为3,5'-二羟基-4′,5-二甲氧基-2′-甲基-[1,1′-联苯]基-2-甲酸(1),其结构通过MS,1D、2D NMR,IR等得到鉴定。 相似文献
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本文报道了以丙酮和EDTA为原料合成N,N'—二羧甲基,N,N'—二(2,2,6,6—四甲基—1—氧基哌啶—4—氧酰甲基)乙二胺的方法。该方法具有产率高、操作简便、易于提纯等优点。 相似文献
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本文报导了从合成1,2—双(1—甲基咪唑—2—硫基)乙烷Ⅱ中得到的新化合物1,2双(1,3—二氢-1-甲基-2-硫代咪唑—3基)乙烷Ⅲ.Ⅲ系Ⅱ之重排物,其结构通过元素分析、NMR、IR、UV 予以鉴定.还发现Ⅲ能与 Hg~(2+),Au~(3+)迅速配位.Ⅱ与 uo_2~(2+)配位. 相似文献
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应用改进的合成砜的方法以获得烯丙基砜,再经二氧化硒和叔丁基过氧化氢氧化并与三溴化磷作用,生成ω-溴代砜,后者在低价铬的作用下与柠檬醛缩合便获得西松烯内酯的一个关键中间体(2E,8E,12E)-3,9,13-三甲基-6(1′甲基乙烯基)-2,8,12-十四碳三烯-7-羟基-苯基砜。 相似文献
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近几年来,我国曾合成了一系列昆虫保幼激素,用于蚕丝增产。为了解决农业上防治害虫的高效低毒药物,本文研究了一类新的具有昆虫保幼激素活性的类似物JS-31——3,7,11-三甲基-2,4-十二碳二烯酸酯的合成。1975年我单位合成了少量的JS-23——3,7,11-三甲基-2,4-十二碳二烯酸-2-丙炔酯;该化合物合成中所需的原料2-丙炔醇当时不易得到,本文改用2-丙烯醇以代替2-丙炔醇,并在合成方法上作了一些必要的改进,制得了JS-31,初步用于防治棉蚜虫及蚕丝增产等方面取得了满意的结果。 相似文献
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Ubiquitin modification is mediated by a large family of specificity determining ubiquitin E3 ligases. To facilitate ubiquitin transfer, RING E3 ligases bind both substrate and a ubiquitin E2 conjugating enzyme linked to ubiquitin via a thioester bond, but the mechanism of transfer has remained elusive. Here we report the crystal structure of the dimeric RING domain of rat RNF4 in complex with E2 (UbcH5A) linked by an isopeptide bond to ubiquitin. While the E2 contacts a single protomer of the RING, ubiquitin is folded back onto the E2 by contacts from both RING protomers. The carboxy-terminal tail of ubiquitin is locked into an active site groove on the E2 by an intricate network of interactions, resulting in changes at the E2 active site. This arrangement is primed for catalysis as it can deprotonate the incoming substrate lysine residue and stabilize the consequent tetrahedral transition-state intermediate. 相似文献
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通过X-单晶衍射确定了标题化合物C17H23O3P(Mr=306.32)的结构.该单晶属于三斜晶系,P
1空间群,a=9.852(1),b=9.887(1),c=19.949(3)A,α=83.161(4),β=87.012(3),y=66.085(3)°,V=1
763.7(4)A3,Z=4,Dc=1.154 g/cm3,F(000)=656,μ=0.163 mm-1,最终反射点的R=0.078
5,wR=0.185 4(I>2σ(Ⅰ)).X-单晶衍射表明标题化合物的三个碳碳双键为全反式构型. 相似文献
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Ye Linbai Gao Jinrong Meng Xiaolin Xu Jinping Zhu Ying Hu Min Min Lei Ye Chanying Wu Zhenhue 《武汉大学学报:自然科学英文版》1996,1(2):279-282
The cDNA containing full encoding region of E1 antigen of HCV was cloned into an expression plasmid pRSETHisB. The recombinant
plasmid pRSETE1 was introduced into the BL21 (DE3) strain ofE. coli. The engineering bacteria harbouring the pRSETE1 was cultivated in 2YT medium at 37°C. When the Expression of E1 protein
was induced by 1 mmol IPTG, the bacteria was killed and the number of living cell was droped down from 107 to 103 cell/mL one hour post induction. Suggest that E1 protein is poisoned toE. coli. However, the 26kD polypeptide of E1 fussion protein still synthesized in appropriate condition. The expression level was
about 10% of total protein 4 h after inducing. The E1 protin was purified by Ni2+-NTA-Agarose column chromatography to homogeneous. The purified E1 protein was sensitive and specific in reaction with anti-HCV
antibody in sera.
Supported by the Science Committec of Hubei Province
Ye Linbai: born in Feb. 1948. Professor 相似文献
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将来自南海红树林内生真菌E33和K38的共培养,从该培养液提取物中分离到Castaneiolide(1),脑苷脂-1-O-吡喃葡萄糖基-(2S,3R,4E,2’R)-2-N-(2’-羟基棕榈酰)-9-甲基-4,8-sphingadienine(2),3β,7β,19-三羟基-5-烯-胆甾烷(3),3-羟基-4-(3-甲基-2-丁烯氧)基-苯甲醛(4),对羟基苯甲醛(5)五个代谢产物,其中化合物1,2,4为首次从海洋真菌里得到。化合物1,2,3,4以往未从单独发酵的两菌中分离得到。 相似文献
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利用比较分子力场方法,建立5-脂氧合酶/环氧合酶抑制剂的三维定量构效关系,为设计新的更有效的酶抑制剂提供理论依据.在CoMFA分析中,交叉验证回归系数R2CV、非交叉验证回归系数r2和标准偏差(SEE)分别为0.639,0.744,0.148.说明系列化合物分子周围立体场和静电场的分布与抗炎活性间有良好的相关性.利用该模型对自行合成的24个化合物进行活性预测,结果与实测值相符.所得模型支持了假设的抑制剂作用机理和作用模型.所得CoMFA模型具有一定的预测能力,可用来指导设计新的5-脂氧合酶/环氧合酶抑制剂. 相似文献
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Modification of proteins with ubiquitin or ubiquitin-like proteins (UBLs) by means of an E1-E2-E3 cascade controls many signalling networks. Ubiquitin conjugation involves adenylation and thioesterification of the carboxy-terminal carboxylate of ubiquitin by the E1-activating enzyme Ube1 (Uba1 in yeast), followed by ubiquitin transfer to an E2-conjugating enzyme through a transthiolation reaction. Charged E2s function with E3s to ubiquitinate substrates. It is currently thought that Ube1/Uba1 is the sole E1 for charging of E2s with ubiquitin in animals and fungi. Here we identify a divergent E1 in vertebrates and sea urchin, Uba6, which specifically activates ubiquitin but not other UBLs in vitro and in vivo. Human Uba6 and Ube1 have distinct preferences for E2 charging in vitro, and their specificity depends in part on their C-terminal ubiquitin-fold domains, which recruit E2s. In tissue culture cells, Uba6 is required for charging a previously uncharacterized Uba6-specific E2 (Use1), whereas Ube1 is required for charging the cell-cycle E2s Cdc34A and Cdc34B. Our data reveal unexpected complexity in the pathways that control the conjugation of ubiquitin, in which dual E1s orchestrate the charging of distinct cohorts of E2s. 相似文献
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利用激光扫描共聚焦显微镜(Confocal microscope)采用pH依赖的荧光探针Snarf-4F测量细胞胞内pH(pHi)方法,发现胞外ATP能剂量依赖(10~1 000 μmol/L)地降低人阴道上皮细胞株VK2/E6E7细胞pHi。当胞外加入200 μmol/L ATP时,能快速地使VK2/E6E7细胞pHi降低,此降低的pHi在洗脱ATP后可迅速恢复。这些结果表明胞外ATP能引起VK2/E6E7细胞胞内酸化。 相似文献