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971.
过氧化物酶是一类广泛存在于生物体内的抗氧化剂,清除有氧代谢过程中产生的活性氧,对于保护机体内的生物大分子有重要的生物学功能。福氏志贺菌硫氧还过氧化物酶(SF2523)作为过氧化物酶家族的一员,通过清除福氏志贺菌体内的活性氧,在维持其活性和致病性上起重要作用。目前,SF2523的三维结构还没有得到解析,其具体的功能机制也尚不清楚。为了得到SF2523蛋白的三维结构,进而了解具体的功能机制,实验获得均一稳定的可溶蛋白,验证具有体外活性,培养出可用于X射线衍射的蛋白质晶体。在中国科学院高能物理研究所同步辐射收到晶体的衍射数据供结构解析使用。SF2523晶体的属于空间群P212121,晶胞参数为a = 35.80 ?, b = 50.63 ?, c = 88.52 ?, α = β = γ = 90.00°,每个晶体学不对称单位含有1个蛋白质分子,马修斯系数为2.03 ?3 /u,溶剂含量为39.56%。 相似文献
972.
目的:探究骨化三醇联合补气口服液对慢性肾功能衰竭患者血清瘦素及睾酮水平的影响。方法:选取我院诊治慢性肾功能衰竭患者116例为研究对象,根据随机数字对照表分为对照组(58例)与试验组(58例)。两组患者均常规给予血管紧张素酶抑制剂或β受体阻滞剂,对照组给予口服骨化三醇胶丸,试验组在对照组的基础上联合给予补气口服液。治疗结束后,比较两组患者肾功能指标、血清瘦素及睾酮水平、营养生化指标。结果:治疗结束后,两组患者血清肌酐(Cr)、血尿素氮(BUN)及瘦素水平均较治疗前显著降低(P0.05),睾酮、血钙水平较治疗前升高(P0.05),血磷水平降低(P0.05)。与对照组相比,试验组血Cr、BUN及瘦素水平较低(P0.05),而血清睾酮、血钙水平较高,血磷水平较低(P0.05)。结论:骨化三醇联合补气口服液能够更有效改善慢性肾功能衰竭患者的肾功能,纠正患者体内电解质紊乱,改善患者食欲不振营养不良症状,推测其与降低血清瘦素水平及升高睾酮水平有关。 相似文献
973.
974.
Giancarlo Gioia Lobbia Claudio Pettinari Carlo Santini Brian W. Skelton 《Inorganica chimica acta》2005,358(4):1162-1170
New silver (I) derivatives containing monodentate tertiary phosphanes and anionic poly(triazol-1-yl)borate ligands have been prepared from the reaction of AgNO3 and PR3 (R = Ph, Bn, o-tolyl, m-tolyl, p-tolyl) and potassium dihydrobis(1,2,4-triazolyl)borate, K[H2B(tz)2], or potassium hydrotris(1,2,4-triazolyl)borate, K[HB(tz)3]; their solid state and solution properties have been investigated through analytical and spectroscopic measurements (IR, 1H-, and 31P NMR). The 1H- and 31P NMR solution spectra in some cases can be interpreted on the basis of a dissociation of [{H2B(tz)2}Ag(PR3)2] into [{H2B(tz)2}Ag(PR3)] and PR3. All the compounds are soluble in chlorinated solvents and are non-electrolytes in CH2Cl2 and acetone solutions. [{H2B(tz)2}Ag(PPh3)2] and [{H2B(tz)2}Ag{P(m-tolyl)3}2] are simple mononuclear arrays, the silver atoms lying in four-coordinate N2AgP2 environments. Owing to the presence of the methyl substituents on the phosphane ligand, the complex [{HB(tz)3}Ag{P(o-tolyl)3}], as expected, is mononuclear. In [{H2B(tz)2}Ag{P(p-tolyl)3}], the silver environment is still four-coordinate but PAgN3, utilizing the coordinating capability of one of the additional (‘exo’-) ring nitrogens not only to complete the four-coordinate array about the silver but, necessarily, to link successive asymmetric units into a single-stranded polymer. 相似文献
975.
Effendy Corrado Di Nicola Brian W. Skelton Allan H. White 《Inorganica chimica acta》2005,358(3):763-795
Single crystal X-ray structural characterizations are recorded for a wide range of adducts of the form MX:dppx (1:1)(n), M = silver(I) (predominantly), copper(I), X = simple (pseudo-) halide or oxy-anion (the latter spanning, where accessible, perchlorate, nitrate, carboxylate - a range of increasing basicity), dppx=bis(diphenylphosphino)alkane, Ph2P(CH2)xPPh2, x = 3-6. Adducts are defined of two binuclear forms: (i) [LM(μ-X)2L], with each ligand chelating a single metal atom, and (ii) [M(μ-X)2(μ-(P-L-P′))2M′] where both ligands L and halides bridge the two metal atoms; a few adducts are defined as polymers, the ligands connecting M(μ-X)2M′ kernels, this motif persisting in all forms. Synthetic procedures for all adducts have been reported. All compounds have been characterized both in solution (1H, 13C, 31P NMR, ESI MS) and in the solid state (IR). 相似文献
976.
Effendy Corrado Di Nicola Claudio Pettinari Brian W. Skelton 《Inorganica chimica acta》2005,358(3):735-747
Syntheses, spectroscopic (IR, NMR and ESI MS) and single crystal X-ray structural characterizations are reported for a wide variety of adducts of Ag(oxyanion):dpem(:S) (1:1(:n))2 (oxyanion = ClO4, F3CCO2 (tfa) F3CSO3 (tfs); dpem = Ph2E(CH2)EPh2) stoichiometry among which the basic Ag(Ph2E(CH2)EPh2)2Ag core is diversely perturbed by interactions with anions and solvent molecules. ESI MS and 31P NMR spectroscopy indicated that dinuclear species also exist in solution. 相似文献
977.
Effendy Claudio Pettinari Massimo Ricciutelli Allan H. White 《Inorganica chimica acta》2005,358(13):4009-4018
1:2, 1:1, 3:2 and 6:2 AgX:L adducts (where L is a tridentate phosphine, in detail: 1,1,1-tris(diphenylphosphinomethyl)ethane (Me-triphos) and bis(2-diphenylphosphinoethyl)phenylphosphine (Ph-triphos), X = O3SCF3, O3SCH3, BF4 or O2CCF3) have been synthesized and characterized by IR, NMR (1H, 31P and 19F) and ESI MS spectroscopy. The stoichiometry of the complexes is strongly dependent on the ligand to metal ratio employed and also on the nature of the counterion. 31P NMR (solution) data also show the complexes existing in solution, in some cases, however, disproportionating to adducts of different nuclearity. Oligonuclear species have been detected through ESI MS spectroscopy that has been demonstrated as a powerful tool for the identification of the solution species. AgBF4:Me-triphos (1:2) has been structurally characterized as [Ag(P,P′-Me-triphos)2](BF4) · H2O · 7/2 MeOH, while Ag(O3SCF3): Ph-triphos: H2O (6:2:4) is a spectacular two-dimensional polymer. 相似文献
978.
Ernesto E. Ambroggio Guadalupe S. Costa Navarro Luis Benito Prez Socas Luis A. Bagatolli Andrea V. Gamarnik 《The Journal of biological chemistry》2021,297(3)
Dengue virus (DENV) and Zika virus (ZIKV) capsid proteins efficiently recruit and surround the viral RNA at the endoplasmic reticulum (ER) membrane to yield nascent viral particles. However, little is known either about the molecular mechanisms by which multiple copies of capsid proteins assemble into nucleocapsids (NCs) or how the NC is recruited and wrapped by the ER membrane during particle morphogenesis. Here, we measured relevant interactions concerning this viral process using purified DENV and ZIKV capsid proteins, membranes mimicking the ER lipid composition, and nucleic acids in in vitro conditions to understand the biophysical properties of the RNA genome encapsidation process. We found that both ZIKV and DENV capsid proteins bound to liposomes at liquid-disordered phase regions, docked exogenous membranes, and RNA molecules. Liquid–liquid phase separation is prone to occur when positively charged proteins interact with nucleic acids, which is indeed the case for the studied capsids. We characterized these liquid condensates by measuring nucleic acid partition constants and the extent of water dipolar relaxation, observing a cooperative process for the formation of the new phase that involves a distinct water organization. Our data support a new model in which capsid–RNA complexes directly bind the ER membrane, seeding the process of RNA recruitment for viral particle assembly. These results contribute to our understanding of the viral NC formation as a stable liquid–liquid phase transition, which could be relevant for dengue and Zika gemmation, opening new avenues for antiviral intervention. 相似文献
979.
Ruthven N.A.H. Lewis 《生物化学与生物物理学报:生物膜》2005,1668(2):203-214
The thermotropic phase behavior of hydrated bilayers derived from binary mixtures of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylglycerol (DMPG) was investigated by differential scanning calorimetry, Fourier-transform infrared spectroscopy and 31P-nuclear magnetic resonance spectroscopy. Binary mixtures of DMPC and DMPG that have not been annealed at low temperatures exhibit broad, weakly energetic pretransitions (∼11-15 °C) and highly cooperative, strongly energetic gel/liquid-crystalline phase transitions (∼23-25 °C). After low temperature incubation, these mixtures also exhibit a thermotropic transition form a lamellar-crystalline to a lamellar gel phase at temperatures below the onset of the gel/liquid-crystalline phase transition. The midpoint temperatures of the pretransitions and gel/liquid-crystalline phase transitions of these lipid mixtures are both maximal in mixtures containing ∼30 mol% DMPG but the widths and enthalpies of the same thermotropic events exhibit no discernable composition dependence. In contrast, thermotropic transitions involving the Lc phase exhibit a very strong composition dependence, and the midpoint temperatures and transition enthalpies are both maximal with mixtures containing equimolar amounts of the two lipids. Our spectroscopic studies indicate that the Lc phases formed are structurally similar as regards their modes of hydrocarbon chain packing, interfacial hydration and hydrogen-bonding interactions, as well as the range and amplitudes of the reorientational motions of their phosphate headgroups. Our results indicate that although DMPC and DMPG are highly miscible, their mixtures do not exhibit ideal mixing. We attribute the non-ideality in their mixing behavior to the formation of preferential PC/PG contacts in the Lc phase due to the combined effects of steric crowding of the DMPC headgroups and charge repulsion between the negatively charged DMPG molecules. 相似文献
980.
Gianni Cavinato Luigi Toniolo Lucio Ronchin Alessandro Dolmella 《Inorganica chimica acta》2005,358(15):4555-4562
The title complex has been synthesized by first reacting dppp with Pd(AcO)2 in acetone and then with NaHSO4 in water. It has been characterized by IR, NMR and X-ray diffraction studies. The 31P NMR spectrum in DMSO shows a singlet at 16.62 ppm indicating that the two P atoms are equivalent and that the sulfate anion is weakly coordinating. The X-ray structure shows that the Pd atom is surrounded in an almost regular square planar environment by the two P atoms and by two O atoms of the sulfate anion and that the neutral complex is accompanied by a water molecule of crystallization. The Pd-P distances (2.217(1) and 2.233(1)) and the P-Pd-P angle (90.78(3)°) are close to those found in other complexes where the chelating diphosphine is the same. Also the Pd-O distances and the O-Pd-O bond angle are comparable to those of other relevant chelating ligands.In MeOH, the title complex, in combination with H2SO4, catalyses the CO-ethene copolymerization. The productivity reaches a maximum upon increasing the H2SO4/Pd ratio up to ca. 470 (7650 g of polyketone/g Pd h at 90 °C and 45 atm, CO/ethene 1/1). The viscosity of the polyketone passes through a maximum of 0.95 dL/g in m-cresol when the above ratio is ca. 100. It has been proposed that acid promotes the copolymerization process by destabilizing the β- and γ-chelates intermediates involved in chain growing process, thus favoring the insertion of the monomers. At relatively high acid concentration the lowering of productivity and viscosity suggests that the sulfate anion competes with the monomers for the coordination to the metal center.In H2O-CH3COOH as a solvent the productivity strongly depends on the H2O/CH3COOH ratio, as it passes through a maximum of 12 000 g polymer/g Pd h in the presence of ca. 60% of H2O. The productivity is significantly lower than that found when the acetate and chloride analogues are used (27 000 g polyketone/g Pd · h). Thus, it is likely that the sulfate anion assists significantly the copolymerization process even though the concentration of CH3COOH/CH3COO− is much preponderant. 相似文献