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51.
Toshihiro Nagao Yuji Shimada Akio Sugihara Aoi Murata Sadao Komemushi Yoshio Tominaga 《Journal of the American Oil Chemists' Society》2001,78(2):167-172
A newly developed 1,3-positionally specific thermostable lipase from Fusarium heterosporum (named R275A lipase) was immobilized on Dowex WBA for the production of structured lipid by acidolysis of tripalmitin (PPP)
with oleic acid (OA). The immobilized catalyst was fully activated by pretreatment at 50°C in a PPP/OA mixture containing
2% water. The pretreatment caused concomitant hydrolysis, but the hydrolysis was repressed using a substrate without water
in the subsequent reactions. The optimal reaction conditions were determined as follows: A mixture of PPP/OA (1∶2, w/w) and
8% immobilized lipase catalyst was incubated at 50°C for 24 h with shaking at 130 oscillations/min. The acidolysis reached
50% under these conditions, and the contents of triolein, 1,3-dioleoyl-2-palmitoyl-glycerol, 1(3),2-dioleoyl-3(1)-palmitoyl-glycerol,
1(3),2-palmitoyl-3(1)-oleoyl-glycerol, 1,3-dipalmitoyl-2-oleoyl-glycerol, and PPP in the reaction mixture were 8, 36, 4, 28,
1, and 6 mol%, respectively. The stabilities of immobilized R275A lipase catalyst and two immobilized catalysts containing
Rhizopus delemar or Rhizomucor miehei lipases were compared under the conditions mentioned above, with the catalysts being transferred to fresh substrate every
24 h. The half-life of the R275A lipase catalyst was 370 d, which was significantly longer than those of Rhizopus and Rhizomucor lipase catalysts. 相似文献
52.
A series of poly(ester amide)s were synthesized by solution polycondensations of various combinations of p‐toluenesulfonic acid salts of O,O′‐bis(α‐aminoacyl)‐1,4:3,6‐dianhydro‐D ‐glucitol and bis(p‐nitrophenyl) esters of aliphatic dicarboxylic acids with the methylene chain lengths of 4–10. The p‐toluenesulfonic acid salts were obtained by the reactions of 1,4:3,6‐dianhydro‐D ‐glucitol with alanine, glycine, and glycylglycine, respectively, in the presence of p‐toluenesulfonic acid. The polycondensations were carried out in N‐methylpyrrolidone at 40°C in the presence of triethylamine, giving poly(ester amide)s having number‐average molecular weights up to 3.8 × 104. Their structures were confirmed by FTIR, 1H‐NMR, and 13C‐NMR spectroscopy. Most of these poly(ester amide)s are amorphous, except those containing sebacic acid and glycine or glycylglycine units, which are semicrystalline. All these poly(ester amide)s are soluble in a variety of polar solvents such as dimethyl sulfoxide, N,N‐dimethylformamide, 2,2,2‐trifluoroethanol, m‐cresol, pyridine, and trifluoroacetic acid. Soil burial degradation tests, BOD measurements in an activated sludge, and enzymatic degradation tests using Porcine pancreas lipase and papain indicated that these poly(ester amide)s are biodegradable, and that their biodegradability markedly depends on the molecular structure. The poly(ester amide)s were, in general, degraded more slowly than the corresponding polyesters having the same aliphatic dicarboxylic acid units, both in composted soil and in an activated sludge. In the enzymatic degradation, some poly(ester amide)s containing dicarboxylic acid components with shorter methylene chain lengths were degraded more readily than the corresponding polyesters with Porcine pancreas lipase, whereas most of the poly(ester amide)s were degraded more rapidly than the corresponding polyesters with papain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2721–2734, 2001 相似文献
53.
Kyohei Koseki Aoi Yamamoto Keisuke Tanimoto Naho Okamoto Fei Teng Tomohiro Bito Yukinori Yabuta Tsuyoshi Kawano Fumio Watanabe 《International journal of molecular sciences》2021,22(23)
(1) Background: Vitamin B12 deficiency in Caenorhabditis elegans results in severe oxidative stress and induces morphological abnormality in mutants due to disordered cuticle collagen biosynthesis. We clarified the underlying mechanism leading to such mutant worms due to vitamin B12 deficiency. (2) Results: The deficient worms exhibited decreased collagen levels of up to approximately 59% compared with the control. Although vitamin B12 deficiency did not affect the mRNA expression of prolyl 4-hydroxylase, which catalyzes the formation of 4-hydroxyproline involved in intercellular collagen biosynthesis, the level of ascorbic acid, a prolyl 4-hydroxylase coenzyme, was markedly decreased. Dityrosine crosslinking is involved in the extracellular maturation of worm collagen. The dityrosine level of collagen significantly increased in the deficient worms compared with the control. However, vitamin B12 deficiency hardly affected the mRNA expression levels of bli-3 and mlt-7, which are encoding crosslinking-related enzymes, suggesting that deficiency-induced oxidative stress leads to dityrosine crosslinking. Moreover, using GMC101 mutant worms that express the full-length human amyloid β, we found that vitamin B12 deficiency did not affect the gene and protein expressions of amyloid β but increased the formation of dityrosine crosslinking in the amyloid β protein. (3) Conclusions: Vitamin B12-deficient wild-type worms showed motility dysfunction due to decreased collagen levels and the formation of highly tyrosine-crosslinked collagen, potentially reducing their flexibility. In GMC101 mutant worms, vitamin B12 deficiency-induced oxidative stress triggers dityrosine-crosslinked amyloid β formation, which might promote its stabilization and toxic oligomerization. 相似文献
54.
Enzymatic degradation of a series of polyesters prepared from 1,4:3.6‐dianhydro‐D ‐glucitol (1) and aliphatic dicarboxylic acids of the methylene chain length ranging from 2 to 10 were examined using seven different enzymes. Enzymatic degradability of these polyesters as estimated by water‐soluble total organic carbon (TOC) measurement is dependent on the methylene chain length (m) of the dicarboxylic acid component for most of the enzymes examined. The most remarkable substrate specificity was observed for Rhizopus delemar lipase, which degraded polyester derived from 1 and suberic acid (m = 6) most readily. In contrast, degradation by Porcine liver esterase was nearly independent of the structure of the polyesters. Enzymatic degradability of the polyesters based on three isomeric 1,4:3.6‐dianhydrohexitols and sebacic acid was found to decrease in the order of 1, 1,4:3.6‐dianhydro‐D ‐mannitol (2), and 1,4:3.6‐dianhydro‐L ‐iditol (3). Structural analysis of water‐soluble degradation products formed during the enzymatic hydrolysis of polyester 5g derived from 1 and sebacic acid has shown that the preferential ester cleavage occurs at the O(5) position of 1,4:3.6‐dianhydro‐D ‐glucitol moiety in the polymer chain by enzymes including Porcine pancreas lipase, Rhizopus delemar lipase, and Pseudomonas sp. lipase. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 338–346, 2000 相似文献
55.
56.
Aoi Isono Dr. Mieko Tsuji Dr. Yu Sanada Akari Matsushita Prof. Dr. Shinichiro Masunaga Dr. Tasuku Hirayama Prof. Dr. Hideko Nagasawa 《ChemMedChem》2019,14(8):823-832
We developed new 10B carriers for boron neutron capture therapy (BNCT) that can effectively transport and accumulate boron clusters into cells. These carriers consist of a lipopeptide, mercaptoundecahydrododecaborate (BSH), and a disulfide linker. The carriers were conceived according to the structure of pepducin, a membrane-penetrating lipopeptide targeting protease-activated receptor 1 (PAR1). To improve the membrane permeability of BSH, the structure was optimized using various lipopeptides possessing different peptides and lipid moieties. These synthesized lipopeptides were conjugated with BSH and evaluated for intracellular uptake using T98G glioblastoma cells. Among them, the most effectively incorporated and accumulated in the cells was compound 5 a , which contains a peptide of 13 residues derived from the intracellular third loop of PAR1 and a palmitoyl group. For further improvement of 10B accumulation in cells, the introduction of an amine linker was investigated; intracellular uptake similar to that of 5 a was observed for compound 14 , which has a piperazine linker. Both compounds 5 a and 14 showed a stronger radiosensitizing effect than BSH along on T98G cells under mixed-neutron beam irradiation. The results demonstrate that lipopeptide conjugation is effective for enhancing intracellular delivery and accumulation of BSH and improving the cytotoxic effect of BNCT. 相似文献
57.
Tracking the Oxygen Status in the Cell Nucleus with a Hoechst‐Tagged Phosphorescent Ruthenium Complex
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Daiki Hara Yui Umehara Dr. Aoi Son Wataru Asahi Sotaro Misu Dr. Ryohsuke Kurihara Dr. Teruyuki Kondo Dr. Kazuhito Tanabe 《Chembiochem : a European journal of chemical biology》2018,19(9):956-962
Molecular oxygen in living cells is distributed and consumed inhomogeneously, depending on the activity of each organelle. Therefore, tractable methods that can be used to monitor the oxygen status in each organelle are needed to understand cellular function. Here we report the design of a new oxygen‐sensing probe for use in the cell nucleus. We prepared “Ru‐Hoechsts”, each consisting of a phosphorescent ruthenium complex linked to a Hoechst 33258 moiety, and characterized their properties as oxygen sensors. The Hoechst unit shows strong DNA‐binding properties in the nucleus, and the ruthenium complex shows oxygen‐dependent phosphorescence. Thus, Ru‐Hoechsts accumulated in the cell nucleus and showed oxygen‐dependent signals that could be monitored. Of the Ru‐Hoechsts prepared in this study, Ru‐Hoechst b , in which the ruthenium complex and the Hoechst unit were linked through a hexyl chain, showed the most suitable properties for monitoring the oxygen status. Ru‐Hoechsts are probes with high potential for visualizing oxygen fluctuations in the nucleus. 相似文献
58.
Aggregate Formation of Oligonucleotides that Assist Molecular Imaging for Tracking of the Oxygen Status in Tumor Tissue
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Kazuki Yoshihara Kohei Takagi Dr. Aoi Son Dr. Ryohsuke Kurihara Dr. Kazuhito Tanabe 《Chembiochem : a European journal of chemical biology》2017,18(16):1650-1658
The use of DNA aggregates could be a promising strategy for the molecular imaging of biological functions. Herein, phosphorescent oligodeoxynucleotides were designed with the aim of visualizing oxygen fluctuation in tumor cells. DNA–ruthenium conjugates (DRCs) that consisted of oligodeoxynucleotides, a phosphorescent ruthenium complex, a pyrene unit for high oxygen responsiveness, and a nitroimidazole unit as a tumor‐targeting unit were prepared. In general, oligonucleotides have low cell permeability because of their own negative charges; however, the DRC formed aggregates in aqueous solution due to the hydrophobic pyrene and nitroimidazole groups, and smoothly penetrated the cellular membrane to accumulate in tumor cells in a hypoxia‐selective manner. The oxygen‐dependent phosphorescence of DRC in cells was also observed. In vivo experiments revealed that aggregates of DRC accumulated in hypoxic tumor tissue that was transplanted into the left leg of mice, and showed that oxygen fluctuations in tumor tissue could be monitored by tracking of the phosphorescence emission of DRC. 相似文献
59.
Various copolyesters were synthesized by bulk polycondensation of the respective combinations of 1,4;3,6‐dianhydro‐D ‐glucitol (1) as the diol component and 1,1‐bis[5‐(methoxycarbonyl)‐2‐furyl]ethane (3b) and seven dimethyl dialkanoates with methylene chain lengths of 4, 5, 6, 7, 8, 10, and 12 (4a–4g) as the dicarboxylic acid components. Most of the copolyesters were amorphous, while a copolyester composed of 1, 3b, and dodecanedioic acid (4g) (3b:4g = 25:75) units as well as homopolyesters derived from 1 and azelaic acid (4d), sebacic acid (4e), and dodecandioic acid (4g), respectively, were partially crystalline. All these homo‐ and copolyesters were soluble in chloroform, dichloromethane, pyridine, trifluoroacetic acid, and m‐cresol. The number‐average molecular weights of these polyesters were estimated to be in the range of 10,000–20,000 by SEC using chloroform as an eluent and standard polystyrene as a reference. The biodegradability of these copolyesters was assessed by enzymatic degradation using four different enzymes in a phosphate buffer solution at 37°C and by soil burial degradation tests in composted soil at 27°C. In general, biodegradability of the copolyesters decreased with increase in the difuran dicarboxylate 3b content. Copolyesters containing sebasic acid 4e units showed higher biodegradability. Soil burial degradation in the soil that was treated with antibiotics, together with electron microscopic observation, indicated that actinomycetes are mainly responsible for the degradation of the copolyesters containing 3b units in the present soil burial test. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3342–3350, 1999 相似文献
60.
A series of polyesters was synthesized by the bulk polycondensations of the respective combinations of three stereoisomeric 1,4 : 3,6-dianhydrohexitols [1,4 : 3,6-dianhydro-D-glucitol ( 1 ), 1,4 : 3,6-dianhydro-D-mannitol ( 2 ), and 1,4 : 3,6-dianhydro-L-iditol ( 3 )] with succinyl dichloride ( 4a ), glutaryl dichloride ( 4b ), adipoyl dichloride ( 4c ), and sebacoyl dichloride ( 4d ). Biodegradability of these polyesters was investigated by three different methods, i.e., degradation in an activated sludge, soil burial degradation, and enzymatic degradation. Although polyesters ( 7b–7d ) based on 3 and polyester 6a derived from 2 and 4a were crystalline and scarcely biodegraded, all the other amorphous polyesters were more or less biodegradable. Biodegradability of the polyesters was found to vary significantly depending on their molecular structures. Soil burial degradation of polyesters in the soil that was treated with antibiotics, together with electron scanning microscopic observation, showed that polyesters 5b and 5c prepared from 1 and 4b or 4c were degraded by both bacteria and filamentous fungi, whereas polyester 5d from 1 and 4d was degraded primarily by filamentous fungi. © 1996 John Wiley & Sons, Inc. 相似文献