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31.
A tetrapeptide, RGDS, was inserted into proUK kringle domain G118-L119 by the construction of a mutant proUK-RGDS gene. The gene was expressed in the baculovirus expression system. Immunoaffinity chromatography was used to purify the chimera and protein with purity over 90% was achieved. The chimera was tested for its platelet membrane binding function and showed a calcium-dependent platelet binding activity. Amidolytic activity of the chimera was tested. The result indicated that specific amidolytic activity of plasmin activated chimera was 62000 IU/mg, comparable to the previously reported 65 355 IU/mg of plasmin activated natural proUK. Activation of plasminogen by the chimera after plasmin treatment followed Micbieal-Menten kinetics, and the Km was 0.97 μmol/L, which was also comparable to 1.64 μmol/L of native urokinase. The chimera also showed intensive ability to inhibit platelet aggregation in vitro. These results indicate that this chimera might be useful as a bifunctional thrombolytic agent. 相似文献
32.
兔肝金属硫蛋白结合铅离子的圆二色性光谱研究 总被引:1,自引:0,他引:1
从锌诱导的家兔肝脏中分离纯化得到金属硫蛋白两种亚型:ZnMT-Ⅰ和ZnMT-Ⅱ.在酸性条件下脱金属,经Sephadex G-25柱层析得到脱金属硫蛋白(apoMTs).用圆二色性(CD)光谱法研究,发现两种亚型apoMTs 与Pb2+ 的结合依赖于Pb2+ 的加入比例及pH 值.apoMT-Ⅰ在pH3~5之间,apoMT-Ⅱ在pH4~6之间与Pb2+ 结合形成特征簇合物Pb7MTs,其CD谱图特征峰位于316nm (- ),270 nm (+ ),245 nm (+ )及225 nm (- ),提示解铅中毒的最佳条件应控制在弱酸性环境.不同亚型apoMTs 与Pb2+ 的结合方式各不相同:Pb2+ 与apoMT-Ⅰ的结合采取平均分配的方式,而与apoMT-Ⅱ则为选择性结合方式,表明这两种亚型在解铅毒功能上存在差异. 相似文献
33.
蚯蚓中抗肿瘤蛋白组分的提取分离及其抗肿瘤活性 总被引:13,自引:0,他引:13
以赤子爱胜蚓为原料 ,通过蛋白质的丙酮沉淀和凝胶过滤 ,分离得到一组抗肿瘤活性蛋白成分 (简称蚯蚓抽提物 ) ;这组成分富含Fe、Zn、Cu以及Se等微量元素 ,蛋白含量为 6 0 4 3± 2 36 %(n =5 ) .体外实验中 ,通过MTT法和SRB法测定了蚯蚓抽提物对多种人癌细胞株 (HCT 116、SY5Y、K5 6 2、MGc80 3和HeLa)以及正常细胞株 (HEK2 93和COS 7)的抑制杀伤率 .结果表明 ,蚯蚓抽提物对癌细胞的杀伤有一定的选择性 ,受试人癌细胞达到 5 0 %生长抑制率所需作用浓度约 6 0~110mg L ;但是 ,10 0℃煮沸 5min后 ,该抑制活性完全消失 .通过纤维蛋白平板法 ,测得蚯蚓抽提物同时具有纤溶酶和纤溶酶原激活酶的活性 .体外测得丝氨酸蛋白酶抑制剂aprotinin和PMSF能显著抑制蚯蚓抽提物的细胞杀伤活性 .体内实验中 ,蚯蚓抽提物能有效延长荷瘤 (S180 )小鼠的生存时间 ,并使其身体机能得到明显改善 .腹膜内注射剂量为 2 8mg kg和 36mg kg时 ,生命延长率分别为135 3%和 12 3 5 % ,和标准药物 (环磷酰胺 )治疗后结果 (76 5 % )相比 ,有显著性差异 相似文献
34.
RU ZHANG JEFFREY A. CRUZ DAVID M. KRAMER MARIA E. MAGALLANES-LUNDBACK DEAN DELLAPENNA & THOMAS D. SHARKEY 《Plant, cell & environment》2009,32(11):1538-1547
We measured the Δ Ψ and ΔpH components of the transthylakoid proton motive force ( pmf ) in light-adapted, intact tobacco leaves in response to moderate heat. The Δ Ψ causes an electrochromic shift (ECS) in carotenoid absorbance spectra. The light–dark difference spectrum has a peak at 518 nm and the two components of the pmf were separated by following the ECS for 25 s after turning the light off. The ECS signal was deconvoluted by subtracting the effects of zeaxanthin formation (peak at 505 nm) and the qE-related absorbance changes (peak at 535 nm) from a signal measured at 520 nm. Heat reduced ΔpH while Δ Ψ slightly increased. Elevated temperature accelerated ECS decay kinetics likely reflecting heat-induced increases in proton conductance and ion movement. Energy-dependent quenching (qE) was reduced by heat. However, the reduction of qE was less than expected given the loss of ΔpH. Zeaxanthin did not increase with heat in light-adapted leaves but it was higher than would be predicted given the reduced ΔpH found at high temperature. The results indicate that moderate heat stress can have very large effects on thylakoid reactions. 相似文献
35.
哺乳动物胚胎发育受遗传和表观遗传的共同调控.精子作为重要的雄性生殖细胞,通过受精过程,将这些信息传递给卵子,进而影响子代的发育.精子中携带有丰富的表观遗传信息,其中小非编码RNAs(small noncoding RNAs,sncRNAs)在精子发育不同阶段发挥重要的作用,包括调控基因表达、介导蛋白质翻译,以及参与精子... 相似文献
36.
37.
Xin HU Qing-Feng WU Ya-Hong XIE Hong RU Feng XIE Xin-Yu WANG Chong-Ying WANG 《植物学报(英文版)》2005,47(10):1153-1158
A novel knottedl-like homeobox (knox) gene, Pttknl (Populus tremula×tremuloides knotted1), isolated from the cambial region of hybrid aspen, was introduced into Petunia hybrida Vilm. using the leafdisc method mediated by Agrobacterium. A series of novel phenotypes was observed in transgenic petunia plants, including the formation of ectopic spikes on the adaxial surface of corollas and small petals on theabaxial surface of corollas, fusion of floral organs, shortening of corolla midribs, the formation of tumor-like knots along the midrib on the abaxial surface and serrated lobs of corolla margins, and alterations in petal color; except for changes in the leaves and plant architecture, RT-PCR showed that the Pttknl gene was expressed in the leaves of different petunia transgenic plants, whereas no signal was detected in wild-type plants. The possible function of Pttknl in leaf and flower development is discussed. 相似文献
38.
Using a non-radioisotopic, quantitative TRAP-based method detecting telomerase activities in human hepatoma cells 总被引:2,自引:0,他引:2
INTRODUCTIONTelomerase is a ribonucleoprotein complex that plays a critical role in telomeremaintenance and cellular immortality. Telomerase has been considered as tumordiagnostic marker and potential target for cancer therapyll, 2]. A sensitive, reliableand quantitative assay is of high interest in this field. The development of a very sensitive Telomeric Repeat Amplification Protocol (TRAP) for measuring telomerajseactivity in cell extracts has been proved to be an important tool for… 相似文献
39.
用 PCR方法构建了一个不能形成二聚体的 C端缺失半胱氨酸 57的 h ITF突变体 .将其克隆到大肠杆菌表达载体 p GEX- 4T- 1中 ,ITPG诱导表达 ,融合蛋白经 Glutathione- Sepharose 4B亲和层析 ,凝血酶酶切和 Sephacryl S 1 0 0纯化 ,得到突变体蛋白 .SDS- PAGE,氨基酸组成 ,飞行质谱 ,N端氨基酸序列测定结果与期望值一致 .研究表明突变体的生物学活性有所降低 .对胃蛋白酶作用的稳定性降低 . 相似文献
40.