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1.
人工合成的Cu2O材料多为1微米以下的纳米尺寸晶体.而尺寸在100微米以上的Cu2O单晶是由金属铜高温氧化获得的Cu2O通过区域熔融或水热重结晶法获得.本文叙述了由乙酸铜为前驱物合成Cu2O单晶的溶剂热合成法,非常方便地合成了大量高品质、尺寸在100~300微米范围的Cu2O单晶.X-射线单晶衍射分析和对大宗样品做了x-射线粉末衍射表征都证明,产物为空间群Pn3 m的立方Cu2O.  相似文献   

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Store-operated Ca2+ entry describes the phenomenon that connects a depletion of internal Ca2+ stores to an activation of plasma membrane-located Ca2+ selective ion channels. Tremendous progress towards the underlying molecular mechanism came with the discovery of the two respective limiting components, STIM and Orai. STIM1 represents the ER-located Ca2+ sensor and transmits the signal of store depletion to the plasma membrane. Here it couples to and activates Orai, the highly Ca2+-selective pore-forming subunit of Ca2+ release-activated Ca2+ channels. In this review, we focus on the molecular steps that these two proteins undergo from store-depletion to their coupling, the activation, and regulation of Ca2+ currents.  相似文献   

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Ca2+/Calmodulin-dependent Protein Kinases   总被引:1,自引:0,他引:1  
In this article the calcium/calmodulin-dependent protein kinases are reviewed. The primary focus is on the structure and function of this diverse family of enzymes, and the elegant regulation of their activity. Structures are compared in order to highlight the conserved architecture of their catalytic domains with respect to each other as well as protein kinase A, a prototype for kinase structure. In addition to reviewing structure and function in these enzymes, the variety of biological processes for which they play a mediating role are also examined. Finally, how the enzymes become activated in the intracellular setting is considered by exploring the reciprocal interactions that exist between calcium binding to calmodulin when interacting with the CaM-kinases.  相似文献   

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Ca2+ in biological systems   总被引:1,自引:0,他引:1  
S Ebashi 《Experientia》1985,41(8):978-981
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在超临界CO2中以聚合物PEG20000为模板,乙酰丙酮铁为前驱体制备Fe2O3多孔材料.研究了压力和温度对插嵌率的影响,并对材料进行了TG、XRD、N2吸脱附及SEM等表征.X射线衍射结果表明,产物主要由α-Fe2O3组成.根据产物的N2吸附-脱附等温线计算,产物的比表面积可迭361.01 m2/g,平均孔径为8 nm左右.SEM测试结果表明,产物由形状不规则的带有疏松结构的碎片组成.  相似文献   

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The cystic phenotype in autosomal dominant polycystic kidney disease is characterized by a profound dysfunction of many cellular signaling patterns, ultimately leading to an increase in both cell proliferation and apoptotic cell death. Disturbance of normal cellular Ca2+ signaling seems to be a primary event and is clearly involved in many pathways that may lead to both types of cellular responses. In this review, we summarize the current knowledge about the molecular and functional interactions between polycystins and multiple components of the cellular Ca2+-signaling machinery. In addition, we discuss the relevant downstream responses of the changed Ca2+ signaling that ultimately lead to increased proliferation and increased apoptosis as observed in many cystic cell types.  相似文献   

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Zusammenfassung Der Ca2+-Transport und die Ca2+-aktivierte ATP Hydrolyse (ATP extra Spaltung) durch Membranen des cardialen sarkoplasmatischen Retikulums zeigen die gleiche Temperaturabhängigkeit. Die Aktivierungsenergie der Ca2+-Aufnahme und der ATP extra Spaltung, gemessen bei Anwesenheit von Oxalat, beträgt 16.65±0.87 und 17.93±0.49 Kcal/Mol–1.  相似文献   

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Mitochondria contain a specific Ca2+ release pathway which operates when oxidized mitochondrial pyridine nucleotides are hydrolyzed. NAD+ hydrolysis and therefore Ca2+ release is possible when some vicinal thiols are cross-linked. Here we report that the thiol oxidant peroxovanadate inhibits the specific Ca2+ release pathway. In mitochondria, peroxovanadate causes a complete loss of reduced glutathione, which is not accompanied by formation of glutathione disulfide, and a partial loss of protein thiols. In model reactions, peroxovanadate oxidizes reduced glutathione predominantly to the sulfonate derivative, but does not react with glutathione disulfide. When the vicinal thiols relevant for Ca2+ release are cross-linked, Ca2+ release is no longer inhibited by peroxovanadate. Conversely, pretreatment of mitochondria with peroxovanadate makes them insensitive to compounds promoting the disulfide state. These results suggest that peroxovanadate inhibits the prooxidant-induced Ca2+ release from mitochondria by (i) depleting mitochondria of reduced glutathione and (ii) oxidizing the vicinal thiols relevant for Ca2+ release to a state higher than disulfide, presumably the sulfonate state. The findings provide further insight into the regulation of Ca2+ release from intact mitochondria, and may be relevant for a better understanding of the action of peroxovanadate in cells, where the compound can be insulin mimetic. Received 28 March 2002; received after revision 8 May 2002; accepted 15 May 2002  相似文献   

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Summary L-[3-2H,18O]glycerol was prepared and fed toEscherichia coli in order to determine the origin of the oxygen atom in the biosynthesized thiazole moiety of thiamine. Measurement by GC-MS of the isotope incorporation into the thiazole from this substrate confirmed that the 2 hydrogens and the oxygen on the C-3 carbon of glycerol are incorporated directly into the thiazole.  相似文献   

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Summary A calmodulin stimulated Ca2+-transport ATPase which has many of the characteristics of the erythrocyte type Ca2+-transport ATPase has been purified from smooth muscle. In particular, the effect of calmodulin on these transport enzymes is mimiced by partial proteolysis and antibodies against erythrocyte Ca2+-transport ATPase also bind to the smooth muscle (Ca2++Mg2+)ATPase. A correlation between the distribution of the calmodulin stimulated (Ca2++Mg2+)ATPase and (Na++K+)ATPase activities in smooth muscle membranes separated by density gradient centrifugation suggests a plasmalemmal distribution of this (Ca2++Mg2+)ATPase. A phosphoprotein intermediate in smooth muscle which strongly resembles the corresponding phosphoprotein in sarcoplasmic reticulum of skeletal muscle may indicate the presence in smooth muscle of a similar type of Ca2+-transport ATPase.  相似文献   

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Summary The effects of La3+ and ruthenium red on the energy-linked uptake of Ca2+ mediated by a synthetic neutral Ca2+ ionophore have been investigated in rat liver mitochondria. The results indicate that unspecific surface charge effects do not play a major role in the mechanism of inhibition of mitochondrial Ca2+ transport by La3+ and ruthenium red.Acknowledgments. The authors are indebted to Prof. W. Simon, ETH Zurich, for having provided samples of the synthetic neutral Ca2+ ligand, and to M. Mattenberger for the valuable technical assistence. The work was supported by a grant of the Swiss Nationalfonds (grant No. 3.1720.75).  相似文献   

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Zusammenfassung Membranen sekretorischer Granula wurden von der Ohrspeicheldrüse (Parotis) der Ratte isoliert und auf Kalzium-ATPase-Aktivität (Ca2+-ATPase) untersucht und postuliert, dass die gefundene Ca2+-ATPase eine Rolle in der Aufnahme und Abgabe von Kalzium in sekretorischen Granula spielt.  相似文献   

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Summary Cytostatic -aminoketones are found to produce H2O2 on autoxidation. Possible pathways of radical and peroxidative reactions in cytostatic therapy are discussed.  相似文献   

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