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991.
Takashi Nishikaze Shin-ichirou Kawabata Koichi Tanaka 《Journal of the American Society for Mass Spectrometry》2014,25(6):988-998
Glycopeptide structural analysis using tandem mass spectrometry is becoming a common approach for elucidating site-specific N-glycosylation. The analysis is generally performed in positive-ion mode. Therefore, fragmentation of protonated glycopeptides has been extensively investigated; however, few studies are available on deprotonated glycopeptides, despite the usefulness of negative-ion mode analysis in detecting glycopeptide signals. Here, large sets of glycopeptides derived from well-characterized glycoproteins were investigated to understand the fragmentation behavior of deprotonated N-linked glycopeptides under low-energy collision-induced dissociation (CID) conditions. The fragment ion species were found to be significantly variable depending on their amino acid sequence and could be classified into three types: (i) glycan fragment ions, (ii) glycan-lost fragment ions and their secondary cleavage products, and (iii) fragment ions with intact glycan moiety. The CID spectra of glycopeptides having a short peptide sequence were dominated by type (i) glycan fragments (e.g., 2,4AR, 2,4AR-1, D, and E ions). These fragments define detailed structural features of the glycan moiety such as branching. For glycopeptides with medium or long peptide sequences, the major fragments were type (ii) ions (e.g., [peptide + 0,2X0–H]– and [peptide–NH3–H]–). The appearance of type (iii) ions strongly depended on the peptide sequence, and especially on the presence of Asp, Asn, and Glu. When a glycosylated Asn is located on the C-terminus, an interesting fragment having an Asn residue with intact glycan moiety, [glycan + Asn–36]–, was abundantly formed. Observed fragments are reasonably explained by a combination of existing fragmentation rules suggested for N-glycans and peptides. Figure
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992.
Koichi Kutsuzawa Toshihiro Suzuki Hidehiro Kishimoto Akiichi Murakami Takachika Azuma Ryo Abe Hidenori Otsuka 《Colloid and polymer science》2014,292(4):839-848
Recombinant Chinese hamster ovary (rCHO) cells have been the most commonly used mammalian host for large-scale commercial production of therapeutic proteins. Although recent advances in 3D culture of rCHO cells is preferred to 2D monolayer culture for highly productive and robust expression of therapeutic proteins, there exists still limitation for efficient protein production. Therefore, a new cell culture system is essentially required for an efficient protein production. Here, we report on a new 3D cell culture system as a spheroid cell culture on the micropattern array for efficient production of protein by CHO cells. Particularly, cocultivation of CHO spheroids with bovine aortic endothelial cells (BAEC) as a feeder layer cells was essential to stably increase a protein production. We investigated the co-culture mechanism of functional enhancement with respect to the cell–cell interactions. Functional comparison between 2D and 3D co-cultures suggested the preferred configuration as spheroid for higher protein production. Specifically, to estimate the effect of respective cell constitution in co-cultured spheroids on the protein production per CHO cell, the number of viable cells in cell proliferation was determined with culture periods. These studies demonstrated the significant role of micropatterned BAEC as a feeder layer for the retained formation of CHO spheroids, resulting in predominantly enhanced production of proteins, although the functional enhancement of CHO cells was obtained by co-culture with BAECs in both 2D and 3D configurations. Thus, heterotypic cell communications that play indispensable roles in increasing CHO functions should be properly obtained in 3D cell configurations. Significantly, these spheroids in the serum-free medium drastically enhanced protein expression level up to sevenfold compared with CHO monospheroids, suggesting that a suitable culture conditions for heterotypic cell–cell interactions would allow improved protein secretion to occur unimpeded. 相似文献
993.
Dr. Hiroaki Itoh Kensuke Miura Koichi Kamiya Dr. Tomoya Yamashita Prof. Dr. Masayuki Inoue 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(11):4594-4601
We report a solid-phase strategy for total synthesis of the peptidic natural product yaku'amide B ( 1 ), which exhibits antiproliferative activity against various cancer cells. Its linear tridecapeptide sequence bears four β,β-dialkylated α,β-dehydroamino acid residues and is capped with an N-terminal acyl group (NTA) and a C-terminal amine (CTA). To realize the Fmoc-based solid-phase synthesis of this complex structure, we developed new methods for enamide formation, enamide deprotection, and C-terminal modification. First, traceless Staudinger ligation enabled enamide formation between sterically encumbered alkenyl azides and newly designed phosphinophenol esters. Second, application of Eu(OTf)3 led to chemoselective removal of the enamide Boc groups without detaching the resin linker. Finally, resin-cleavage and C-terminus modification were simultaneously achieved with an ester–amide exchange reaction using CTA and AlMe3 to deliver 1 in 9.1 % overall yield (24 steps from the resin). 相似文献
994.
Paradigm Shift from Alkaline (Earth) Metals to Early Transition Metals in Fluoroorganometal Chemistry: Perfluoroalkyl Titanocene(III) Reagents Prepared via Not Titanocene(II) but Titanocene(III) Species 下载免费PDF全文
Motohiro Fujiu Ryota Hashimoto Yuzo Nakamura Prof. Dr. Kohsuke Aikawa Prof. Dr. Shigekazu Ito Prof. Dr. Koichi Mikami 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(8):2382-2386
Perfluoroalkyl (RF) titanocene reagents [Cp2TiIIIRF] synthesized via [Cp2TiIIICl] rather than [Cp2TiII] show new types of perfluoroalkylation reactions. The [Cp2TiIIIRF] reagents exhibit a wide variety of reactivity with carbonyl compounds including esters and nitriles, and selectivities far higher than those reported for conventional RFLi and RFMgX reagents. 相似文献
995.
High Performance Photoinitiating Systems for Holography Recording: Need for a Full Control of Primary Processes 下载免费PDF全文
Dr. Ahmad Ibrahim Prof. Xavier Allonas Prof. Christian Ley Dr. Koichi Kawamura Dr. Horst Berneth Dr. Friedrich‐Karl Bruder Dr. Thomas Fäcke Dr. Rainer Hagen Dr. Dennis Hönel Dr. Thomas Rölle Dr. Guenther Walze Dr. Marc Stephan Weiser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(46):15102-15107
Optimization of holography recording in photopolymers was studied from the point of view of a quite general process, that is, the photogeneration of radicals. On the basis of a dye/coinitiator photoinitiating system, the effect of primary events and their relative efficiency was investigated with respect to the final overall properties, such as the diffraction efficiency. Quenching of the dye excited states by the borate salts coinitiators exhibits important differences depending on the dye used (Rose Bengal or Safranine O). Keeping in mind that both singlet and triplet states of the dyes can react, and taking into account the viscosity of the matrix, a method to evaluate the overall quantum yield of radicals released is proposed. It is found that this quantum yield well correlates with the maximum rate of photopolymerization. More interestingly, the dose required to obtain a given diffraction efficiency was found to be also governed by the radical quantum yield, showing that the final property is directly governed by primary events. This shed some light on the efficiency of photochemical pathway to generate radicals for use in organic or polymer areas. 相似文献
996.
Dr. Ryo Shintani Ryuhei Fujie Dr. Momotaro Takeda Prof. Dr. Kyoko Nozaki 《Angewandte Chemie (International ed. in English)》2014,53(25):6546-6549
A potassium‐bis(trimethylsilyl)amide‐mediated cyclopropanation of allyl phosphates with silylboronates has been developed. Unlike the reported copper‐catalyzed allylic substitution reactions, the nucleophile selectively attacks at the β‐position of the allylic substrates under the present reaction conditions. The mechanism of this process has also been investigated, thus indicating the involvement of a silylpotassium species as the active nucleophilic component. 相似文献
997.
Kei Zaitsu Izuru Miyawaki Kiyoko Bando Hiroshi Horie Noriaki Shima Munehiro Katagi Michiaki Tatsuno Takeshi Bamba Takako Sato Akira Ishii Hitoshi Tsuchihashi Koichi Suzuki Eiichiro Fukusaki 《Analytical and bioanalytical chemistry》2014,406(5):1339-1354
The metabolic profiles of urine and blood plasma in drug-addicted rat models based on morphine (MOR), methamphetamine (MA), and cocaine (COC)-induced conditioned place preference (CPP) were investigated. Rewarding effects induced by each drug were assessed by use of the CPP model. A mass spectrometry (MS)-based metabolomics approach was applied to urine and plasma of MOR, MA, and COC-addicted rats. In total, 57 metabolites in plasma and 70 metabolites in urine were identified by gas chromatography–MS. The metabolomics approach revealed that amounts of some metabolites, including tricarboxylic acid cycle intermediates, significantly changed in the urine of MOR-addicted rats. This result indicated that disruption of energy metabolism is deeply relevant to MOR addiction. In addition, 3-hydroxybutyric acid, l-tryptophan, cystine, and n-propylamine levels were significantly changed in the plasma of MOR-addicted rats. Lactose, spermidine, and stearic acid levels were significantly changed in the urine of MA-addicted rats. Threonine, cystine, and spermidine levels were significantly increased in the plasma of COC-addicted rats. In conclusion, differences in the metabolic profiles were suggestive of different biological states of MOR, MA, and COC addiction; these may be attributed to the different actions of the drugs on the brain reward circuitry and the resulting adaptation. In addition, the results showed possibility of predict the extent of MOR addiction by metabolic profiling. This is the first study to apply metabolomics to CPP models of drug addiction, and we demonstrated that metabolomics can be a multilateral approach to investigating the mechanism of drug addiction. 相似文献
998.
Koichi Kaizuka 《Journal of Functional Analysis》2019,276(2):329-379
In this paper we develop the scattering theory for the Laplacian on symmetric spaces of noncompact type. We study the asymptotic properties of the resolvent in the framework of the Agmon–Hörmander space. Our approach is based on a detailed analysis of the Helgason Fourier transform and generalized spherical functions on symmetric spaces of noncompact type. As an application of our scattering theory, we prove a conjecture by Strichartz concerning a characterization of a family of generalized eigenfunctions of the Laplacian. 相似文献
999.
Boundedness of solutions to parabolic–elliptic Keller–Segel systems with signal‐dependent sensitivity 下载免费PDF全文
Kentarou Fujie Michael Winkler Tomomi Yokota 《Mathematical Methods in the Applied Sciences》2015,38(6):1212-1224
This paper deals with the parabolic–elliptic Keller–Segel system with signal‐dependent chemotactic sensitivity function, under homogeneous Neumann boundary conditions in a smooth bounded domain , with initial data satisfying u0 ≥ 0 and . The chemotactic sensitivity function χ(v) is assumed to satisfy The global existence of weak solutions in the special case is shown by Biler (Adv. Math. Sci. Appl. 1999; 9:347–359). Uniform boundedness and blow‐up of radial solutions are studied by Nagai and Senba (Adv. Math. Sci. Appl. 1998; 8:145–156). However, the global existence and uniform boundedness of classical nonradial solutions are left as an open problem. This paper gives an answer to the problem. Namely, it is shown that the system possesses a unique global classical solution that is uniformly bounded if , where γ > 0 is a constant depending on Ω and u0. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
1000.
Masamitsu Tanaka Pawel Mroz Tianhong Dai Liyi Huang Yuji Morimoto Manabu Kinoshita Yasuo Yoshihara Nariyoshi Shinomiya Shuhji Seki Koichi Nemoto Michael R. Hamblin 《Photochemistry and photobiology》2013,89(3):679-682
We previously reported that photodynamic therapy (PDT) using intra‐articular methylene blue (MB) could be used to treat arthritis in mice caused by bioluminescent methicillin‐resistant Staphylococcus aureus (MRSA) either in a therapeutic or in a preventative mode. PDT accumulated neutrophils into the mouse knee via activation of chemoattractants such as inflammatory cytokines or chemokines. In this study, we asked whether PDT combined with antibiotics used for MRSA could provide added benefit in controlling the infection. We compared MB‐PDT alone, systemic administration of either linezolid (LZD) alone or vancomycin (VCM) alone or the combination of PDT with either LZD or VCM. Real‐time noninvasive imaging was used to serially follow the progress of the infection. PDT alone was the most effective, whereas LZD alone was ineffective and VCM alone showed some benefit. Surprisingly the addition of LZD or VCM reduced the therapeutic effect of PDT alone (P < 0.05). Considering that PDT in this mouse model stimulates neutrophils to be antibacterial rather than actively killing the bacteria, we propose that LZD and VCM might inhibit the activation of inflammatory cytokines without eradicating the bacteria, and thereby reduce the therapeutic effect of PDT. 相似文献