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991.
992.
《Bioscience, biotechnology, and biochemistry》2013,77(1):26-33
Rhodococcus jostii RHA1 is a polychlorinated biphenyl degrader. Multi-component biphenyl 2,3-dioxygenase (BphA) genes of RHA1 encode large and small subunits of oxygenase component and ferredoxin and reductase components. They did not express enzyme activity in Escherichia coli. To obtain BphA activity in E. coli, hybrid BphA gene derivatives were constructed by replacing ferredoxin and/or reductase component genes of RHA1 with those of Pseudomonas pseudoalcaligenes KF707. The results obtained indicate a lack of catalytic activity of the RHA1 ferredoxin component gene, bphAc in E. coli. To determine the cause of inability of RHA1 bphAc to express in E. coli, the bphAc gene was introduced into Rosetta (DE3) pLacI, which has extra tRNA genes for rare codons in E. coli. The resulting strain abundantly produced the bphAc product, and showed activity. These results suggest that codon usage bias is involved in inability of RHA1 bphAc to express its catalytic activity in E. coli. 相似文献
993.
Ryan J. Mailloux Jian Ying Xuan Brittany Beauchamp Linda Jui Marjorie Lou Mary-Ellen Harper 《The Journal of biological chemistry》2013,288(12):8365-8379
Glutathionylation has emerged as a key modification required for controlling protein function in response to changes in cell redox status. Recently, we showed that the glutathionylation state of uncoupling protein-3 (UCP3) modulates the leak of protons back into the mitochondrial matrix, thus controlling reactive oxygen species production. However, whether or not UCP3 glutathionylation is mediated enzymatically has remained unknown because previous work relied on the use of pharmacological agents, such as diamide, to alter the UCP3 glutathionylation state. Here, we demonstrate that glutaredoxin-2 (Grx2), a matrix oxidoreductase, is required to glutathionylate and inhibit UCP3. Analysis of bioenergetics in skeletal muscle mitochondria revealed that knock-out of Grx2 (Grx2−/−) increased proton leak in a UCP3-dependent manner. These effects were reversed using diamide, a glutathionylation catalyst. Importantly, the increased leak did not compromise coupled respiration. Knockdown of Grx2 augmented proton leak-dependent respiration in primary myotubes from wild type mice, an effect that was absent in UCP3−/− cells. These results confirm that Grx2 deactivates UCP3 by glutathionylation. To our knowledge, this is the first enzyme identified to regulate UCP3 by glutathionylation and is the first study on the role of Grx2 in the regulation of energy metabolism. 相似文献
994.
4-Hydroxynonenal (HNE) is the most studied end product of the lipoperoxidation process, by virtue of its relevant biological activity. The antiproliferative and proapoptotic effects of HNE have been widely demonstrated in a great variety of tumor cell types in vitro. Thus, it might represent a promising new molecule in anticancer therapy strategies. However, the extreme reactivity of this aldehyde, as well as its insolubility in water, a limiting factor for drug bioavailability, and its rapid degradation by specific enzymes represent major obstacles to its possible in vivo application. Various strategies can used to overcome these problems. One of the most attractive strategies is the use of nanovehicles, because loading drugs into nanosized structures enhances their stability and solubility, thus improving their bioavailability and their antitumoral effectiveness. Several natural or synthetic polymers have been used to synthesize nanosized structures and, among them, β-cyclodextrin (βCD) polymers are playing a very important role in drug formulation by virtue of the ability of βCD to form inclusion compounds with a wide range of solid and liquid molecules by molecular complexation. Moreover, several βCD derivatives have been designed to improve their physicochemical properties and inclusion capacities. Here we report that the inclusion complex of HNE with a derivative of βCD, the βCD–poly(4-acryloylmorpholine) conjugate (PACM-βCD), enhances the aldehyde stability. Moreover, the inclusion of HNE in PACM-βCD potentiates its antitumor effects in several tumor cell lines and in a more complex system, such as a human reconstructed skin carrying melanoma tumor cells. 相似文献
995.
The DOPAC/DA ratio in mouse striatum, in striatal synaptosomes, and in rat urine after MPP+ and MPTP neurotoxin administrations to the animals was followed temporally. The neurotoxins were given intraperitoneally and, in some experiments, to enhance the sensitivity, the animals were subsequently reserpinized before either sacrifice or 24 hour urine collection. MPP+ treatment, followed by saline, weakly lowered mouse striatal DOPAC/DA ratio up to 6 hours; in reserpinized animals, however, the neurotoxin reduced striatal ratio potently and for longer periods. Similarly, MPP+ reduced rat (saline treated) urinary DOPAC level and DOPAC/DA ratio in the short term (1.0 hr) while the neurotoxin effects could still be detected following longer periods up to 27 days in reserpinized animals. A single MPTP treatment (90 min.), followed by preparation of striatal synaptosomal fraction and its incubation (37°C) with or without reserpine, also led to a reduced DOPAC/DA ratio. Although mainly the pooled peripheral effect is directly indicated by urinary DOPAC/DA ratio, MPP+ may reduce DA oxidation in the CNS and may similarly affect the amine oxidation in the peripheral tissues. The CNS and peripheral effects differ, however, in respect to dose-sensitivity and time course. The similarities between the CNS and peripheral effects suggest that a blunted rise of urinary DOPAC/DA ratio after reserpine challenge could be utilized as a peripheral marker of MPP+ action in the CNS, a marker that is not currently available. 相似文献
996.
磷酸酪氨酸蛋白专一抗体的制备和纯化 总被引:1,自引:0,他引:1
以偶联磷酸化酪氨酸的牛血清白蛋白(BSA)作为免疫原免疫兔获得抗血清.自抗血清中分离获得抗体.自酪胺合成磷酸酪胺,并偶联到溴化氰活化的Sepharose4B上.抗体经磷酸酪胺-Sepharose4B亲和柱纯化,所得抗体专一性强,Dotblot显示:抗体仅对酪氨酸磷酸化的蛋白质包括酪氨酸磷酸化的血清白蛋白,溶菌酶,卵清蛋白起抗原抗体反应,而不识别非酪氨酸磷酸化的溶菌酶,卵清蛋白,也不识别作为免疫原的骨架成分BSA,也不识别丝氨酸磷酸化的卵清蛋白和苏氨酸磷酸化的卵清蛋白. 相似文献
997.
998.
中国棉铃虫核型多角体病毒DNA聚合酶基因的克隆和序列分析 总被引:4,自引:0,他引:4
应用谷实夜蛾核型多角体病毒(HzSNPV)DNA聚合酶基因HindⅢ/PstⅠ3596bp片段作探针,经Sourthernblot杂交,克隆了中国棉铃虫核型多角体病毒(HaSNPV)完整的DNA聚合酶基因,大小约为3.4kb。限制性内切酶分析表明,HaSNPVDNA聚合酶基因限制性内切酶图谱与HzSNPV相似。用双脱氧链终止法测定该基因部分核苷酸序列(805bp),推导出编码区206a。序列同源性比较显示,HaSNPVDNA聚合酶与HzSNPV之间具有高度的同源性;与LdMNPV、AcMNPV、BmSNPV、CfMNPV和OpMNPV也具有一定的同源性 相似文献
999.
1000.
The diterpene forskolin stimulated rat cardiac adenylate cyclase activity at least 20-fold and potentiated the effect of NaF. The stimulatory effect of forskolin was reduced in the presence of Gpp(NH)p. Ethanol markedly reduced the stimulation of adenylate cyclase by forskolin while potentiating NaF and Gpp(NH)p stimulation. The inhibitory effect of ethanol on forskolin stimulation appeared to be of a mixed type with both a competitive and a non-competitive component. Three other short-chain linear alcohols (methanol, propanol, butanol) also inhibited forskolin-stimulation, this effect being proportional to the number of carbon atoms. 相似文献