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71.
MS/MS is indispensable for the amino acid sequencing of peptides. However, its use is limited for peptides containing disulfide bonds. We have applied the reducing properties of 1,5-diaminonaphthalene (1,5-DAN) as a MALDI matrix to amino acid sequencing and disulfide bond mapping of human urotensin II possessing one disulfide bond, and human guanylin possessing two disulfide bonds. 1,5-DAN was used in the same manner as the usual MALDI matrices without any pre-treatment of the peptide, and MS/MS was performed using a matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometer (MALDI QIT TOFMS). The results demonstrated that MS/MS of the molecular ions reduced by 1,5-DAN provided a series of significant b-/y-product ions. All 11 amino acid residues of urotensin II were identified using 1,5-DAN, while only 5 out of 11 residues were identified using 2,5-dihydroxybenzoic acid (DHB); similarly 11 out of 15 amino acid residues of guanylin were identified using 1,5-DAN, while only three were identified using DHB. In addition, comparison of the theoretical and measured values of the mass differences between corresponding MS/MS product ions using 1,5-DAN and DHB narrowed down the possible disulfide bond arrangement candidates. Consequently, 1,5-DAN as a reductive matrix facilitates rapid amino acid sequencing and disulfide mapping for peptides containing disulfide bonds. 相似文献
72.
A novel method for the preparation of N-acylpyrrole is described. The method involves condensation of carboxylic acids with 2,4,4-trimethoxybutan-1-amine, followed by acid-mediated cyclization to form the pyrrole ring. The preparative procedure is highly tolerant of a variety of functional groups. 相似文献
73.
K Iwasaki R Kanno T Morimoto T Yamashita S Yokoshima T Fukuyama 《Angewandte Chemie (International ed. in English)》2012,51(36):9160-9163
What a core-ker! The title synthesis was achieved using a route featuring an intramolecular Mitsunobu reaction of a nosyl amide, stereoselective construction of the β-lactam, and formation of an enamide moiety by selenoxide elimination. The stereochemistry of the alkylation for the formation of the β-lactam was controlled by a secondary hydroxy group on the ten-membered ring. SEM=2-(trimethylsilyl)ethoxymethyl; TBS=tert-butyldimethylsilyl. 相似文献
74.
75.
Farshi E. Fukuyama T. Matsukuma M. Kawai Y. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2001,29(6):907-910
In a DC discharge plasma system, in which two meshes are installed, the current-driven ion acoustic instability is excited when a de potential Vm is applied to one of them. When the instability fully grows, the system reaches a very turbulence state, the so-called ion acoustic turbulence. The experimental measurement of energy distribution function of electrons in ion acoustic turbulence measured by the Langmuir probe shows a non-Maxwellian nature along with electron heating 相似文献
76.
Hitomi Kawakami Takahisa Sakurai Yoshiyasu Ehara Toshiaki Yamamoto Akinori Zukeran 《Journal of Electrostatics》2013,71(6):1117-1123
The novel electrohydrodynamically-assisted electrostatic precipitator (EHD ESP) was developed to suppress particle reentrainment for collection of low resistive diesel particulates. The collection efficiency was compared between vertically and horizontally oriented electrodes of the EHD ESP using 400 cc diesel engine. The particle size dependent collection efficiency was evaluated for the particle size ranging in 20 to 5000 nm using a scanning mobility particle sizer (SMPS) and a particle counter (PC). Both horizontally and vertically oriented EHD ESP showed an excellent suppression of particle reentrainment. However, the horizontally oriented electrode EHD ESP showed significantly improved for the particle size of 300–500 nm in comparison with vertically oriented electrode EHD ESP, resulting in more than 90% collection efficiency for all particle size range. The EHD ESP has high potential especially for highly concentrated marine diesel engine emission control. 相似文献
77.
Sound transmission between adjoining rooms is often influenced by a flanking sound passing through open windows placed in the exterior wall of the two rooms. It is important to predict such flanking sound propagation when considering the sound insulation between the adjoining rooms. In this paper, a chart for estimating the distance attenuation of the flanking sound, which is obtained from analysis using the boundary integral equation method, is first provided. Next, 1:10 scale model experiments are carried out. The experimental results are in good agreement with the chart, the effectiveness of the chart thus being verified. 相似文献
78.
Minoru Isobe Yasunori Funabashi Yoshiyasu Ichikawa Shigeru Mio Toshio Goto 《Tetrahedron letters》1984,25(19):2021-2024
A stereoselective synthesis of both syn- and anti-diastereoisomers (3 and 4) was established by a method involving heteroconjugate addition, as the key step, with various nucleophiles such as alkoxyvinyllithiums which can be functionalized after the addition. Two examples with aliphatic and carboxylic groups are demonstrated in high specificity. 相似文献
79.
A variety of unsymmetrically substituted 2,5-piperazinediones have been synthesized by regioselective alkylation of piperazinedione derivatives. 相似文献
80.