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51.
Kyoko TakahashiKenichiro Hashimoto Ayako FujiyamaJunko Yamada Noriko KobayashiMasuo Morisaki Sayaka NakanoNoriyuki Hara Yoshinori Fujimoto 《Tetrahedron letters》2003,44(2):341-344
Feeding of the chemically prepared [24-13C, 24-2H]desmosterol to cell-free systems derived from rat liver and silkworm gut and to cultured cells of Oryza sativa followed by deuterium-decoupled 1H, 13C shift correlation NMR analysis of the biosynthesized cholesterol revealed the stereospecific incorporation of hydrogen atoms from the re-face of the C-24 position of desmosterol. 相似文献
52.
Motoo Tori Aki Watanabe Yasuko Okamoto Shigeru Takaoka Chiaki Kuroda Ryo Hanai 《Tetrahedron》2008,64(19):4486-4495
Twenty-six eremophilane-type sesquiterpenoids, including six new compounds, were isolated from the title species. One of the new compounds, kanaitzensol, suggested the presence of an enzyme for the conversion of eremophil-7(11)-en-8-one derivative to furanoeremophilanes. The plant was collected at 15 locations in Yunnan Province of China and found to be diverse with respect to its sesquiterpenoid composition. DNA sequencing also revealed a large intraspecific diversity of the plant. 相似文献
53.
The "elution-band relaxation method" has been applied to the analysis of the cis-trans kinetics isomerization of the proline of L-Ala-L-Pro using reversed-phase liquid chromatography. A procedure suitable for cases where neither isomer can be injected separately is described. 相似文献
54.
Honda S Akiba T Kato YS Sawada Y Sekijima M Ishimura M Ooishi A Watanabe H Odahara T Harata K 《Journal of the American Chemical Society》2008,130(46):15327-15331
What is the smallest protein? This is actually not such a simple question to answer, because there is no established consensus among scientists as to the definition of a protein. We describe here a designed molecule consisting of only 10 amino acids. Despite its small size, its essential characteristics, revealed by its crystal structure, solution structure, thermal stability, free energy surface, and folding pathway network, are consistent with the properties of natural proteins. The existence of this kind of molecule deepens our understanding of proteins and impels us to define an "ideal protein" without inquiring whether the molecule actually occurs in nature. 相似文献
55.
Kousaku Ohkawa Kengo Ichimiya Ayako Nishida Hiroyuki Yamamoto 《Macromolecular bioscience》2001,1(9):376-386
The adhesive polydecapeptide poly(Lys‐Pro‐Thr‐Gln‐Tyr‐Ser‐Asp‐Glu‐Tyr‐Lys) (average repeating number, n = 5), which is the consensus sequence of the Asian freshwater mussel Limnoperna fortunei adhesive protein (Lffp), has been synthesized by the polycondensation of the active esters. The surface chemical experiments revealed the following characteristics of the freshwater adhesive protein: (i) wettability of the Lffp solution is affected by the polar component value (γsp) of the surface free energy of the substrate, and a substrate having a γsp less than 10 mJ·m–2 exhibits a reduced wettability of the Lffp solution; (ii) the comparison of wettability of native Lffp with synthetic Lffp suggests that the decapeptide sequence, ‐Lys‐Pro‐Thr‐Gln‐Tyr‐Ser‐Asp‐Glu‐Tyr‐Lys‐, contributes to the interaction with the underwater surface; (iii) the Lffp tends to adsorb on nonpolar surfaces that have a low γsp value; and (iv) the adsorption ability of the freshwater adhesive protein is less than that of the marine adhesive protein because of the higher hydrophilicity of the freshwater adhesive protein. An antifouling examination indicated that a γsp value of the substrate surface of less than 10 mJ·m–2 should achieve a higher antifouling effect towards the L. fortunei attachment. These results are the first findings for the development of a freshwater antifouling strategy based on the molecular mechanism underlying the attachment of L. fortunei. 相似文献
56.
Simultaneous quantification of leukotrienes and hydroxyeicosatetraenoic acids in cell culture medium using liquid chromatography/tandem mass spectrometry 下载免费PDF全文
Leukotrienes (LTs) and hydroxyeicosatetraenoic acids (HETEs) are important bioactive lipid mediators that participate in various pathophysiological processes. To advance understanding of the mechanisms that regulate these mediators in physiological and pathological processes, an analytical method using liquid chromatography/tandem mass spectrometry for the simultaneous quantification of LTB4, LTC4, LTD4, LTE4, 5‐HETE, 8‐HETE, 12‐HETE and 15‐HETE in cell culture media was developed. A Supel?‐Select HLB solid‐phase extraction cartridge was used for sample preparation. The compounds were separated on a C18 column using gradient elution with acetonitrile–water–formic acid (20:80:0.1, v/v/v) and acetonitrile–formic acid (100:0.1, v/v). The calibration curves of LTB4, LTD4, LTE4 and HETEs were linear in the range of 0.025–10 ng/mL, and the calibration curve of LTC4 was linear in the range of 0.25–10 ng/mL. Validation assessment showed that the method was highly reliable with good accuracy and precision. The stability of LTs and HETEs was also investigated. Using the developed method, we measured LTs and HETEs in the culture supernatant of the human mast cell line HMC‐1. The present method could facilitate investigations of the mechanisms that regulate the production, release and signaling of LTs and HETEs. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
57.
Yoh Kodera Ayako Ajima Katsunobu Takahashi Ayako Matsushima Yuji Saito Yuji Inada 《Photochemistry and photobiology》1988,47(2):221-223
Abstract— Hematoporphyrin, having two carboxylic groups, was coupled with α-(3-aminopropyl)-ω-methoxypoly(oxyethylene), PEG-NH2 , through acid-amide bond formed with carbodtimide. PEG-modified hematoporphyrin was readily soluble not only in neutral aqueous solution but also in organic solvents. Its absorption spectrum showed a sharp band at 376 nm in neutral aqueous solution and at 403 nm in benzene. Modified hematoporphyrin acted as a photosensitizer; imidazole and indole were photooxidized in organic solvents such as benzene or chloroform, and uric acid was also photooxidized in neutral aqueous solution. 相似文献
58.
Abdillah Sani Bin Mohd Najib Xiaobo Peng Ayako Hashimoto Shusaku Shoji Takayuki Iida Yunxing Bai Hideki Abe 《化学:亚洲杂志》2019,14(16):2802-2805
Mesoporous precious metals with abundant active sites and high surface area have been widely recognized as high‐performance catalytic materials. However, the templated synthesis is complex and costly. Herein, we report a mesoporous rhodium (m‐Rh) that can be readily synthesized from entangled nanofibres of Rh and Y2O3 without templates. The entangled nanofibres, prepared from uniform Rh‐Y alloys under redox atmosphere, were the key precursor in the synthesis processes. Moreover, the m‐Rh efficiently catalyzed carbon dioxide reforming of methane (DRM) at a low reaction temperature of 683 K. Further, electrochemical methods of CO electro‐oxidation were innovatively used to demonstrate the stability of CO and oxygen species for the DRM reaction. 相似文献
59.
Matsuo Y Muramatsu A Kamikawa Y Kato T Nakamura E 《Journal of the American Chemical Society》2006,128(30):9586-9587
A series of conical molecules featuring a [60]fullerene/ferrocene hybrid and five aralkyl side chains (Fe[C60{C6H4-(OCO-C6H3-(OR)2-3,4)-4}5]Cp) have been synthesized and examined for their structural and electrochemical properties as well as their ability to form supramolecular structures in crystals and liquid crystals. When the R group on the side is a methyl group, the compound forms crystals in which the dipolar conical molecules are stacked head-to-tail to form a columnar structure. When the R group is as long as a C18H38 group, the compound forms liquid crystals. Oxidation of the liquid crystalline compound by an aminium salt [(4-BrC6H4)3N][SbCl6] produces the corresponding paramagnetic Fe(III) compound that also exhibits liquid crystalline properties. 相似文献
60.
Hanai T 《Journal of chromatographic science》2006,44(5):247-252
A quantitative analysis of the retention of aromatic acid derivatives in reversed-phase liquid chromatography (RPLC) is conducted using a molecular mechanics calculation in the CAChe program. The molecular interaction energy value is calculated by subtracting the energy value of the complex from the sum of energy values of a model phase and an analyte. Several model phases are constructed, and the feasibility of applying the method to a variety of compounds is examined based on improving the contact surface area and the capability of computer software and hardware. Interaction energy values are calculated for both molecular and ionic forms. The predicted retention factors of partially ionized acids obtained using a combination of dissociation constants correlated well with the values measured by RPLC with pH-controlled eluents. 相似文献