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The synthesis and characterization of rare-earth (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y) thiocyanate adducts with tripiperidinophosphine oxide (tpppO) with general formula (RE)(SCN)3(tpppO)3 are reported. Conductance measurements in acetonitrile indicate the non-electrolytic nature of the complexes. Infrared absorption spectra evidence that the SCN− ion coordinates through the nitrogen atom (isothiocyanate form) and that tpppO coordinates through the phosphoryl oxygen. X-ray powder patterns suggest the existence of three different crystal forms: (1) La; (2) an isomorphous series including Ce, Nd and Pr; and (3) another isomorphous series, including Sm, Gd, Eu, Ho, Er, Tb, Lu and Y. The visible spectra of the Nd adduct and the calculated parameters β = 0.98, b1/2 = 0.072 and δ = 1.06 indicate that the metal-ligand bonds are essentially electrostactic. The emission spectra of the Eu compound showed 5D0 → 7FJ bands (J = 0, 1, 2), suggesting a C3v symmetry for the coordination polyhedron. The lifetime of the 5D0 state is 1.28 ms. The emission spectra of the Tb complex presented 5D4 → 7FJ bands (J = 4, 5, 6) and the Dy complex showed the 4F9/2 → 6H13/2 band. The structure of the Pr complex showed that the coordination polyhedron is a trigonal antiprism, with the isothiocyanate anions in one base and three tpppO ligands in the other. Thermal analyses (TG-DTG) were carried out for the Ce, Nd and Gd adducts. Mass losses start between 250 and 334 °C. The final residues at 1300 °C are the corresponding phosphates. 相似文献
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David W. Thomas Amabile K. Matida Célio L. Silva Thuioshi Ioneda 《Chemistry and physics of lipids》1979,23(3):267-282
The purification procedure of 6,6′-diesters of trehalose from Corynebacterium diphtheriae was modified and the isolated substance was analysed by mass spectrometry as its permethylated derivative. The fatty acid moiety released from the glycolipid after alkaline hydrolysis was studied by mass spectral analysis of the O-methylated and O-acetylated methyl ester derivatives. By argentation thin-layer chromatography, three species of O-acetylated methyl esters were recognized, corresponding to saturated, mono-unsaturated and di-unsaturated α-branched-β-hydroxylated fatty acids. The double bond was located by ozonolysis of the O-acetylated methyl ester derivatives, by gas chromatography of the reaction product and mass spectrometry of the effluent from the gas chromatograph. The main components of each species of α-branched-β-hydroxylated fatty acids found in the gly colipid fraction of C. diphtheriae were 2-tetradecyl-3-hydroxyoctadecanoic acid (C32H64O3, corynomycolic acid), 2-tetradecyl-3-hydroxy-11-octadecenoic acid (C32H62O3, corynomycolenic acid), 2-tetradec-7′-enyl-3-hydroxy octadecanoic acid (C32H62O3) and 2-tetradec-7′-enyl-3-hydroxy-11-octadecenoic acid (C32H60O3, corynomycoldienic acid). The glycolipid fraction from C. diphtheriae is obviously a complex mixture of 6,6′-diesters of trehalose. 相似文献
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Y. Saijo S. Takeda A. Scherer T. Kobayashi Y. Mada H. Taniguchi M. Yao S. Wakatsuki 《Protein science : a publication of the Protein Society》1997,6(4):916-918
Troponin is a ternary protein complex consisting of subunits TnC. TnI, and TnT, and plays a key role in calcium regulation of the skeletal and cardiac muscle contraction. In the present study, a partial complex (CI47) was prepared from Escherichia coli-expressed rabbit skeletal muscle TnC and fragment 1-47 of TnI, which is obtained by chemical cleavage of an E. coli-expressed mutant of rabbit skeletal muscle TnI. Within the ternary troponin complex, CI47 is thought to form a core that is resistant to proteolytic digestion, and the interaction within CI47 likely maintains the integrity of the troponin complex. Complex CI47 was crystallized in the presence of sodium citrate. The addition of trehalose improved the diffraction pattern of the crystals substantially. The crystal lattice belongs to the space group P3(1)(2)21, with unit cell dimensions a = b = 48.2 A, c = 162 A. The asymmetric unit presumably contains one CI47 complex. Soaking with p-chloromercuribenzenesulfonate (PCMBS) resulted in loss of isomorphism, but enhanced the quality of the crystals. The crystals diffracted up to 2.3 A resolution, with completeness of 91% and R(merge) = 6.4%. The crystals of PCMBS-derivative should be suitable for X-ray studies using the multiple-wavelength anomalous diffraction technique. This is the first step for elucidating the structure of the full troponin complex. 相似文献
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Emmanuelle Fontoura José Darival Ferreira Jamile Bubadué Ana Maria Ribeiro Leonardo Kerber 《Journal of morphology》2020,281(10):1223-1240
A diverse fossil record of Cervidae (Mammalia) has been documented in the South American Pleistocene, when these animals arrived during the Great American Biotic Interchange. Using computed tomography-scanning techniques, it is possible to access the endocranial morphology of extinct species. Here, we studied the brain endocast of the extinct late Pleistocene cervid Antifer ensenadensis from southern Brazil, one of the largest forms that lived on this continent, using comparative morphology, geometric morphometrics, and encephalization quotients. The analyzed endocasts demonstrate that A. ensenadensis had a gyrencephalic brain, showing a prominent longitudinal sinus (=sagittal superior sinus), which is also observed in the large South American cervid Blastocerus dichotomus. The encephalization quotient is within the variation of extant cervids, suggesting maintenance of the pattern of encephalization from at least the late Pleistocene. Geometric morphometric analysis suggested a clear and linear allometric trend between brain endocast size and shape, and highlights A. ensenadensis as an extreme form within the analyzed cervids regarding brain morphology. 相似文献
30.
Samir Jabari Alexandre B. M. da Silveira Enio C. de Oliveira Karl Quint André Wirries Winfried Neuhuber Axel Brehmer 《Cell and tissue research》2014,358(1):75-83
Chagasic megacolon is accompanied by extensive myenteric and, simultaneously, moderate submucosal neuron loss. Here, we examined changes of the innervation pattern of the lamina propria (LP) and muscularis mucosae (MM). Two alternating sets of cryosections were taken from seven non-chagasic colonic and seven chagasic megacolonic specimens (the latter included both the dilated megacolonic and the non-dilated transitional oral and anal zones) and were immunohistochemically triple-stained for smooth-muscle actin (SMA), synaptophysin (SYN) and glial acid protein S100 and, alternatively, for SMA, vasoactive intestinal peptide (VIP) and somatostatin (SOM). Subsequent image analysis and statistical evaluation of nervous tissue profile areas revealed that, in LP, the most extreme differences (i.e. increase in thickness or decrease in nerve, glia and muscle tissue profile area, respectively) compared with control values occurred in the dilated megacolonic zone itself. In contrast, the most extreme differences in the MM were in the anal-to-megacolonic zone (except the profile area of muscle tissue, which was lowest in the megacolonic zone). This parallels our previous results in the external muscle coat. A partial and selective survival of VIP-immunoreactive in contrast to SOM-immunoreactive nerve fibres was observed in both mucosal layers investigated. Thus, VIPergic nerve elements might be crucial for the maintenance of the mucosal barrier. The differential changes of neural tissue parameters in LP and MM might reflect a multifactorial rather than a pure neurogenic development of megacolon in chronic Chagas’ disease. 相似文献