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Ohno K, Manjanath A, Kawazoe Y, Hatakeyama R, Misaizu F, Kwon E, Fukumura H, Ogasawara H, Yamada Y, Zhang C, Sumi N, Kamigaki T, Kawachi K, Yokoo K, Ono S, Kasama Y. Extensive first-principles molecular dynamics study on Li encapsulation into C 60 and its experimental confirmation. Nanoscale 2018; 10:1825-1836. [PMID: 29308793 DOI: 10.1039/c7nr07237f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The aim of increasing the production ratio of endohedral C60 by impinging foreign atoms against C60 is a crucial matter of the science and technology employed towards industrialization of these functional building block materials. Among these endohedral fullerenes, Li+@C60 exhibits a wide variety of physical and chemical phenomena and has the potential to be applicable in areas spanning the medical field to photovoltaics. However, currently, Li+@C60 can be experimentally produced with only ∼1% ratio using the plasma shower method with a 30 eV kinetic energy provided to the impinging Li+ ion. From extensive first-principles molecular dynamics simulations, it is found that the maximum production ratio of Li+@C60 per hit is increased to about 5.1% (5.3%) when a Li+ ion impinges vertically on a six-membered ring of C60 with 30 eV (40 eV) kinetic energy, although many C60 molecules are damaged during this collision. On the contrary, when it impinges vertically on a six-membered ring with 10 eV kinetic energy, the production ratio remains at 1.3%, but the C60 molecules are not damaged at all. On the other hand, when the C60 is randomly oriented, the production ratio reduces to about 3.7 ± 0.5%, 3.3 ± 0.5%, and 0.2 ± 0.03% for 30 eV, 40 eV, and 10 eV kinetic energy, respectively. Based on these observations we demonstrate the possibility of increasing the production ratio by fixing six-membered rings atop C60 using the Cu(111) substrate or UV light irradiation. In order to assess the ideal experimental production ratio, the 7Li solid NMR spectroscopy measurement is also performed for the multilayer randomly oriented C60 sample irradiated by Li+ using the plasma shower method combined with inductively coupled plasma atomic emission spectroscopy (ICP-AES). Time-of-flight mass spectroscopy measurements are also performed to cross check whether Li+@C60 molecules are produced in the sample. The resulting experimental estimate, 4% for 30 eV incident kinetic energy, fully agrees with our simulation results mentioned above, suggesting the consistency and accuracy of our simulations and experiments.
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Affiliation(s)
- K Ohno
- Department of Physics, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
| | - A Manjanath
- Department of Physics, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
| | - Y Kawazoe
- New Industry Creation Hatchery Center, Tohoku University, 6-6-4 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan and Department of Physics and Nanotechnology, SRM University, Kattankulathur 603203, Tamil Nadu, India
| | - R Hatakeyama
- Department of Electronic Engineering, Tohoku University, 6-6-5 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan
| | - F Misaizu
- New Industry Creation Hatchery Center, Tohoku University, 6-6-4 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan and Department of Chemistry, Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8578, Japan
| | - E Kwon
- New Industry Creation Hatchery Center, Tohoku University, 6-6-4 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan and Research and Analytical Center for Giant Molecules, Graduate School of Science, Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8578, Japan
| | - H Fukumura
- Department of Chemistry, Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8578, Japan
| | - H Ogasawara
- Graduate School of Pharmaceutical Science, Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8578, Japan
| | - Y Yamada
- Division of Applied Physics, University of Tsukuba, 1-1-1 Ten'nodai, Tsukuba, Ibaraki 305-8573, Japan
| | - C Zhang
- Division of Applied Physics, University of Tsukuba, 1-1-1 Ten'nodai, Tsukuba, Ibaraki 305-8573, Japan
| | - N Sumi
- Division of Applied Physics, University of Tsukuba, 1-1-1 Ten'nodai, Tsukuba, Ibaraki 305-8573, Japan
| | - T Kamigaki
- Idea International Corporation, 1-15-35 Sagigamori, Aoba-ku, Sendai 981-0922, Japan
| | - K Kawachi
- Idea International Corporation, 1-15-35 Sagigamori, Aoba-ku, Sendai 981-0922, Japan
| | - K Yokoo
- Idea International Corporation, 1-15-35 Sagigamori, Aoba-ku, Sendai 981-0922, Japan
| | - S Ono
- Idea International Corporation, 1-15-35 Sagigamori, Aoba-ku, Sendai 981-0922, Japan
| | - Y Kasama
- Idea International Corporation, 1-15-35 Sagigamori, Aoba-ku, Sendai 981-0922, Japan
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Kudo F, Kasama Y, Hirayama T, Eguchi T. Cloning of the Pactamycin Biosynthetic Gene Cluster and Characterization of a Crucial Glycosyltransferase Prior to a Unique Cyclopentane Ring Formation. J Antibiot (Tokyo) 2007; 60:492-503. [PMID: 17827660 DOI: 10.1038/ja.2007.63] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The biosynthetic gene (pct) cluster for an antitumor antibiotic pactamycin was identified by use of a gene for putative radical S-adenosylmethionine methyltransferase as a probe. The pct gene cluster is localized to a 34 kb contiguous DNA from Streptomyces pactum NBRC 13433 and contains 24 open reading frames. Based on the bioinformatic analysis, a plausible biosynthetic pathway for pactamycin comprising of a unique cyclopentane ring, 3-aminoacetophenone, and 6-methylsalicylate was proposed. The pctL gene encoding a glycosyltransferase was speculated to be involved in an N-glycoside formation between 3-aminoacetophenone and UDP-N-acetyl-alpha-D-glucosamine prior to a unique cyclopentane ring formation. The pctL gene was then heterologously expressed in Escherichia coli and the enzymatic activity of the recombinant PctL protein was investigated. Consequently, the PctL protein was found to catalyze the expected reaction forming beta-N-glycoside. The enzymatic activity of the PctL protein clearly confirmed that the present identified gene cluster is for the biosynthesis of pactamycin. Also, a glycosylation prior to cyclopentane ring formation was proposed to be a general strategy in the biosynthesis of the structurally related cyclopentane containing compounds.
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Affiliation(s)
- Fumitaka Kudo
- Department of Chemistry, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8551, Japan.
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Sakai K, Narihara M, Kasama Y, Wakayama M, Moriguchi M. Purification and characterization of thermostable beta-N-acetylhexosaminidase of Bacillus stearothermophilus CH-4 isolated from chitin-containing compost. Appl Environ Microbiol 1994; 60:2911-5. [PMID: 8085829 PMCID: PMC201742 DOI: 10.1128/aem.60.8.2911-2915.1994] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Thermostable exochitinase was purified to homogeneity from the culture fluid of Bacillus stearothermophilus CH-4, which was isolated from agricultural compost containing shrimp and crabs. The enzyme was a single polypeptide with a molecular mass of 74 kDa, and the N-terminal amino acid sequence was WDKVGVTDLI ISLNIPEADAVVVGMTLQLQALHLY. The enzyme specifically hydrolyzed C-4 beta-anomeric bonding of N-acetylchitooligosaccharides, as well as their p-nitrophenyl (pNP) derivatives. The enzyme also hydrolyzed pNP-beta-N-acetyl-D-galactosaminide (26% of the activity of pNP-beta-N-acetyl-D-glucosaminide). These results indicated that the enzyme is a beta-N-acetylhexosaminidase (EC 3.2.1.52). Kms for acetylchitooligosaccharides were 1 x 10(-4) to 6 x 10(-4) M, while those for the pNP derivatives were 4 x 10(-3) to 8 x 10(-3) M. The optimum temperature of the enzyme was 75 degrees C, and it retained 100 and 28% reactivity after heating at 60 and 80 degrees C, respectively. The enzyme exhibited 15 to 20% activity in a reaction mixture containing 80% organic solvents and maintained 91% of its original activity after exposure to 8 M urea. The optimum and stable pH was around 6.5. Fe2+, Zn2+, and Ca2+ activated the enzyme, but Hg2+ was inhibitory. N-Acetyl-D-glucosamine inhibited the enzyme competitively (Ki = 4.3 x 10(-4) M), whereas N-acetyl-D-galactosamine did not; in contrast, D-glucosamine and D-galactosamine activated it.
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Affiliation(s)
- K Sakai
- Department of Applied Chemistry, Faculty of Engineering, Oita University, Japan
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Abstract
Our observations show that young rabbits born of mothers afflicted with Schistosomum japonicum develop typical rickets. Rickets can also be produced if we infect the young, healthy rabbits with the same parasite. It is natural to suppose that the rachitic changes are caused by the parasite itself. Since, however, a similar disease can be produced in the offspring, when the mother is fed on egg yolk, the causation is not limited to the action of this parasitic toxin alone. The toxin of Schistosoma may disturb the calcium and phosphorus metabolism of bone in young animals, especially in the period of vigorous growth; that is, 20 to 40 days after birth of the rabbits. Or it may exhaust some element important in the calcium and phosphorus metabolism such as vitamin A or D. The fact that exhaustion of the antirachitic factor in the mother causes rickets in the young, as Grant (1924) showed, and that certain low grade infections can exhaust vitamin B as shown by Wedgewood (1924), is in line with this conception. It may be added here that most investigations on rickets have been carried out on rats and dogs. We have found a simple and excellent way of producing rickets in rabbits by dietary deficiency. Concerning this method, we shall report elsewhere.
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Affiliation(s)
- R. Kawamura
- From the Pathological Laboratory of Niigata Medical University, Niigata, Japan
| | - Y. Kasama
- From the Pathological Laboratory of Niigata Medical University, Niigata, Japan
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