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Wilmin P. Bartolini Catherine M. Bentzley Murray V. Johnston Barbara S. Larsen 《Journal of the American Society for Mass Spectrometry》1999,10(6):521-528
Elucidating structure function relationships of DNA in cellular processes requires fast, reliable methods that can be applied to picomole amounts of sample. Higher order structure can be inferred by distinguishing paired and unpaired regions. It is shown here that enzymatic digestion coupled with product analysis by matrix-assisted laser desorption ionization (MALDI) is able to identify unpaired bases within structured DNA regions. The method is demonstrated with DNA duplexes having a five nucleotide mismatch as a 5' overhang, a 3' overhang, and an internal loop. Exo- and endonuclease digestions are performed under solution conditions (temperature, annealing, and enzyme buffers) which promote base pairing and specific enzyme activity. For each type of mismatch, the length and sequence of the single stranded region can be inferred from MALDI spectra taken as a function of digestion time. 相似文献
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Tiziana Parasassi Ewa K. Krasnowska Luis Bagatolli Enrico Gratton 《Journal of fluorescence》1998,8(4):365-373
The steady-state and dynamic fluorescence spectral properties of 2-dimethylamino-6-lauroylnaphthalene (LAURDAN) and several other naphthalene derivatives are summarized to illustrate their sensitivity to the polarity of the environment. Results obtained both in solvents of different polarity and in phospholipid vesicles in two phase states are presented. The emission red shift observed in polar solvents and in the phospholipid liquid–crystalline phase is explained on the basis of dipolar relaxation of solvent molecules surrounding the fluorescent naphthalene moiety of these probes. In phospholipid environments, experimental evidence is shown that excludes the intramolecular relative reorientation of the dimethylamino and carbonyl groups in the naphthalene and the reorientation of the entire fluorescent moiety. The solvent dipolar relaxation observed for LAURDAN and PRODAN in phospholipid bilayers has been attributed to a small number of water molecules present at the membrane interface. A comparison between LAURDAN emission in phospholipid vesicles prepared in D2O and in H2O is also presented. The definition and the derivation of the generalized polarization function are also discussed. 相似文献
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Angel Bustamante Enrico Mattievich Helio S. de Amorim Ivo Vencato Máximo M. Silveira 《Hyperfine Interactions》2005,166(1-4):599-603
The crystal structure of synthetic ferrous hureaulite, Fe5 2+ (H2O)4(PO4H)2(PO4)2, was refined from single-crystal X-ray data. It is monoclinic, space group C2/c, with a=17.487(4), b=9.017(2), c=9.338(2) Å, β=96.27(3)°, V=1463.6(6) Å3, Z=4 and D calc=3.327 g/cm3. This end member of the hureaulite series was crystallized under distinctly acidic conditions, by a method that gives perfect crystals, large enough for X-ray single crystal studies. The main feature of the hureaulite structure is that it has an equal number of normal (PO4)3+ and acid (PO4H)2+ tetradentate groups. These are centered on Fe2+ atoms and share corners with edge-linked octahedra, forming pentamer units. The five Fe2+ atoms are distributed on three distinct sites in these units. This can be directly observed in the Mössbauer spectrum at 295 K, which contains three doublets whose relative intensities correspond to the 1:2:2 distributions of crystallographic sites. 相似文献
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Enrico Sanjust Raffaello Pompei Antonio Rescigno Augusto Rinaldi Maoro Ballero 《Applied biochemistry and biotechnology》1991,31(3):223-235
Four species of Pleurotus were adapted to grow on olive milling wastewater, and in certain conditions produced high yield of fruit bodies. Some biochemical transformations were observed in the olive milling wastewater owing to the growth of Pleurotus. In particular, the fungi actively excreted large amounts of laccase in the medium, and at the same time the concentration of phenolics and other toxic compounds significantly decreased, as revealed by HPLC analysis and toxicity tests on standard cultures of human cell lines. 相似文献
140.
Many beautiful experiments have been addressed to test standard quantum mechanics against local realistic models. Even if a strong evidence favouring standard quantum mechanics is emerged, a conclusive experiment is still lacking, because of low detection efficiencies. Recently, experiments based on pseudoscalar mesons have been proposed as a way for obtaining a conclusive experiment. In this paper, we investigate if this result can effectively be obtained. Our conclusions, based on a careful analysis of the proposed set ups, are that this will not be possible due to intrinsic limitations of these kind of experiments. 相似文献