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Sureshkumar S, Lee HC, Lee S, Jung SK, Kim D, Oh KB, Yang H, Jo YJ, Lee S, Byun SJ. Preliminary Study to Investigate the Effect of Lactobacillus Reuteri Administration on Growth Performance, Immunological, Gut Microbiome and Intestinal Mucosa of Chicken. Braz J Poult Sci 2022. [DOI: 10.1590/1806-9061-2022-1640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- S Sureshkumar
- National Institute of Animal Science, Republic of Korea; Dankook University, Republic of Korea
| | - HC Lee
- National Institute of Animal Science, Republic of Korea
| | - S Lee
- National Institute of Animal Science, Republic of Korea
| | - SK Jung
- National Institute of Animal Science, Republic of Korea
| | - D Kim
- Sungkyunkwan University, Republic of Korea
| | - KB Oh
- National Institute of Animal Science, Republic of Korea
| | - H Yang
- National Institute of Animal Science, Republic of Korea
| | - YJ Jo
- National Institute of Animal Science, Republic of Korea
| | - S Lee
- Sungkyunkwan University, Republic of Korea
| | - SJ Byun
- National Institute of Animal Science, Republic of Korea
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2
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Jo YJ, Lee HI, Kim N, Hwang D, Lee J, Lee GR, Hong SE, Lee H, Kwon M, Kim NY, Kim HJ, Park JH, Kang YH, Kim HS, Lee SY, Jeong W. Cinchonine inhibits osteoclast differentiation by regulating TAK1 and AKT, and promotes osteogenesis. J Cell Physiol 2021; 236:1854-1865. [PMID: 32700766 DOI: 10.1002/jcp.29968] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 06/26/2020] [Accepted: 07/14/2020] [Indexed: 01/09/2023]
Abstract
Cinchonine (CN) has been known to exert antimalarial, antiplatelet, and antiobesity effects. It was also recently reported to inhibit transforming growth factor β-activated kinase 1 (TAK1) and protein kinase B (AKT) through binding to tumor necrosis factor receptor-associated factor 6 (TRAF6). However, its role in bone metabolism remains largely unknown. Here, we showed that CN inhibits osteoclast differentiation with decreased expression of nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1), a key determinant of osteoclastogenesis. Immunoblot and quantitative real-time polymerase chain reaction analysis as well as the reporter assay revealed that CN inhibits nuclear factor-κB and activator protein-1 by regulating TAK1. CN also attenuated the activation of AKT, cyclic AMP response element-binding protein, and peroxisome proliferator-activated receptor-γ coactivator 1β (PGC1β), an essential regulator of mitochondrial biogenesis. Collectively, these results suggested that CN may inhibit TRAF6-mediated TAK1 and AKT activation, which leads to downregulation of NFATc1 and PGC1β resulting in the suppression of osteoclast differentiation. Interestingly, CN not only inhibited the maturation and resorption function of differentiated osteoclasts but also promoted osteoblast differentiation. Furthermore, CN protected lipopolysaccharide- and ovariectomy-induced bone destruction in mouse models, suggesting its therapeutic potential for treating inflammation-induced bone diseases and postmenopausal osteoporosis.
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Affiliation(s)
- You-Jin Jo
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Hye In Lee
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Narae Kim
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Donghyun Hwang
- Department of Biomedical Engineering, Yonsei University, Wonju, Republic of Korea
| | - Jiae Lee
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Gong-Rak Lee
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Seong-Eun Hong
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Hana Lee
- Department of Biomedical Engineering, Yonsei University, Wonju, Republic of Korea
| | - Minjeong Kwon
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Nam Young Kim
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Hyun Jin Kim
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Jin Ha Park
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Ye Hee Kang
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Han Sung Kim
- Department of Biomedical Engineering, Yonsei University, Wonju, Republic of Korea
| | - Soo Young Lee
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Woojin Jeong
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
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Lee J, Son HS, Lee HI, Lee GR, Jo YJ, Hong SE, Kim N, Kwon M, Kim NY, Kim HJ, Lee YJ, Seo EK, Jeong W. Skullcapflavone II inhibits osteoclastogenesis by regulating reactive oxygen species and attenuates the survival and resorption function of osteoclasts by modulating integrin signaling. FASEB J 2018; 33:2026-2036. [PMID: 30216110 DOI: 10.1096/fj.201800866rr] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Many bone diseases, such as osteoporosis and rheumatoid arthritis, are attributed to an increase in osteoclast number or activity; therefore, control of osteoclasts has significant clinical implications. This study shows how skullcapflavone II (SFII), a flavonoid with anti-inflammatory activity, regulates osteoclast differentiation, survival, and function. SFII inhibited osteoclastogenesis with decreased activation of MAPKs, Src, and cAMP response element-binding protein (CREB), which have been known to be redox sensitive. SFII decreased reactive oxygen species by scavenging them or activating nuclear factor-erythroid 2-related factor 2 (Nrf2), and its effects were partially reversed by hydrogen peroxide cotreatment or Nrf2 deficiency. In addition, SFII attenuated survival, migration, and bone resorption, with a decrease in the expression of integrin β3, Src, and p130 Crk-associated substrate, and the activation of RhoA and Rac1 in differentiated osteoclasts. Furthermore, SFII inhibited osteoclast formation and bone loss in an inflammation- or ovariectomy-induced osteolytic mouse model. These findings suggest that SFII inhibits osteoclastogenesis through redox regulation of MAPKs, Src, and CREB and attenuates the survival and resorption function by modulating the integrin pathway in osteoclasts. SFII has therapeutic potential in the treatment and prevention of bone diseases caused by excessive osteoclast activity.-Lee, J., Son, H. S., Lee, H. I., Lee, G.-R., Jo, Y.-J., Hong, S.-E., Kim, N., Kwon, M., Kim, N. Y., Kim, H. J., Lee, Y. J., Seo, E. K., Jeong, W. Skullcapflavone II inhibits osteoclastogenesis by regulating reactive oxygen species and attenuates the survival and resorption function of osteoclasts by modulating integrin signaling.
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Affiliation(s)
- Jiae Lee
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Han Saem Son
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Hye In Lee
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Gong-Rak Lee
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - You-Jin Jo
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Seong-Eun Hong
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Narae Kim
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Minjeong Kwon
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Nam Young Kim
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Hyun Jin Kim
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
| | - Yoo Jin Lee
- College of Pharmacy, Ewha Womans University, Seoul, South Korea
| | - Eun Kyoung Seo
- College of Pharmacy, Ewha Womans University, Seoul, South Korea
| | - Woojin Jeong
- Department of Life Science, Research Center for Cellular Homeostasis, Ewha Womans University, Seoul, South Korea
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Hong SE, Lee J, Seo DH, In Lee H, Ri Park D, Lee GR, Jo YJ, Kim N, Kwon M, Shon H, Kyoung Seo E, Kim HS, Young Lee S, Jeong W. Euphorbia factor L1 inhibits osteoclastogenesis by regulating cellular redox status and induces Fas-mediated apoptosis in osteoclast. Free Radic Biol Med 2017; 112:191-199. [PMID: 28774817 DOI: 10.1016/j.freeradbiomed.2017.07.030] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 07/11/2017] [Accepted: 07/29/2017] [Indexed: 02/01/2023]
Abstract
Excessive bone resorption caused by increased osteoclast number or activity leads to a variety of bone diseases including osteoporosis, rheumatoid arthritis and periodontitis. Thus, the therapeutic strategy for these diseases has been focused primarily on the inhibition of osteoclast formation and function. This study shows that euphorbia factor L1 (EFL1), a diterpenoid isolated from Euphorbia lathyris, inhibited osteoclastogenesis and induced osteoclast apoptosis. EFL1 suppressed osteoclast formation and bone resorption at both initial and terminal differentiation stages. EFL1 inhibited receptor activator of NF-κB ligand (RANKL)-induced NFATc1 induction with attenuated NF-κB activation and c-Fos expression. EFL1 decreased the level of reactive oxygen species by scavenging them or activating Nrf2, and inhibited PGC-1β that regulates mitochondria biogenesis. In addition, EFL1 induced apoptosis in differentiated osteoclasts by increasing Fas ligand expression followed by caspase activation. Moreover, EFL1 inhibited inflammation-induced bone erosion and ovariectomy-induced bone loss in mice. These findings suggest that EFL1 inhibits osteoclast differentiation by regulating cellular redox status and induces Fas-mediated apoptosis in osteoclast, and may provide therapeutic potential for preventing or treating bone-related diseases caused by excessive osteoclast.
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Affiliation(s)
- Seong-Eun Hong
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Jiae Lee
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Dong-Hyun Seo
- Department of Biomedical Engineering, College of Health Science, Institute of Medical Engineering, Yonsei University, Wonju, Republic of Korea
| | - Hye In Lee
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Doo Ri Park
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Gong-Rak Lee
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - You-Jin Jo
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Narae Kim
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Minjung Kwon
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Hansem Shon
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Eun Kyoung Seo
- College of Pharmacy, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Han-Sung Kim
- Department of Biomedical Engineering, College of Health Science, Institute of Medical Engineering, Yonsei University, Wonju, Republic of Korea
| | - Soo Young Lee
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Woojin Jeong
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, Republic of Korea.
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Kim J, Lee GR, Kim H, Jo YJ, Hong SE, Lee J, Lee HI, Jang YS, Oh SH, Lee HJ, Lee JS, Jeong W. Effective killing of cancer cells and regression of tumor growth by K27 targeting sulfiredoxin. Free Radic Biol Med 2016; 101:384-392. [PMID: 27825965 DOI: 10.1016/j.freeradbiomed.2016.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 11/01/2016] [Accepted: 11/02/2016] [Indexed: 01/23/2023]
Abstract
Cancer cells have been suggested to be more susceptible to oxidative damages and highly dependent on antioxidant capacity in comparison with normal cells, and thus targeting antioxidant enzymes has been a strategy for effective cancer treatment. Sulfiredoxin (Srx) is an enzyme that catalyzes the reduction of sulfinylated peroxiredoxins and thereby reactivates them. In this study we developed a Srx inhibitor, K27 (N-[7-chloro-2-(4-fluorophenyl)-4-quinazolinyl]-N-(2-phenylethyl)-β-alanine), and showed that it induces the accumulation of sulfinylated peroxiredoxins and oxidative stress, which leads to mitochondrial damage and apoptotic death of cancer cells. The effects of K27 were significantly reversed by ectopic expression of Srx or antioxidant N-acetyl cysteine. In addition, K27 led to preferential death of tumorigenic cells over non-tumorigenic cells, and suppressed the growth of xenograft tumor without acute toxicity. Our results suggest that targeting Srx might be an effective therapeutic strategy for cancer treatment through redox-mediated cell death.
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Affiliation(s)
- Jiwon Kim
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea
| | - Gong-Rak Lee
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea
| | - Hojin Kim
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea
| | - You-Jin Jo
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea
| | - Seong-Eun Hong
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea
| | - Jiae Lee
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea
| | - Hye In Lee
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea
| | - Yeong-Su Jang
- Gachon Institute of Pharmaceutical Science, Gachon University, Incheon 406-840, South Korea
| | - Seung-Hyun Oh
- Gachon Institute of Pharmaceutical Science, Gachon University, Incheon 406-840, South Korea
| | - Hwa Jeong Lee
- College of Pharmacy, Ewha Womans University, Seoul 120-750, South Korea
| | - Ju-Seog Lee
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA
| | - Woojin Jeong
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea.
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Kim H, Lee GR, Kim J, Baek JY, Jo YJ, Hong SE, Kim SH, Lee J, Lee HI, Park SK, Kim HM, Lee HJ, Chang TS, Rhee SG, Lee JS, Jeong W. Sulfiredoxin inhibitor induces preferential death of cancer cells through reactive oxygen species-mediated mitochondrial damage. Free Radic Biol Med 2016; 91:264-74. [PMID: 26721593 DOI: 10.1016/j.freeradbiomed.2015.12.023] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 11/05/2015] [Accepted: 12/19/2015] [Indexed: 01/08/2023]
Abstract
Recent studies have shown that many types of cancer cells have increased levels of reactive oxygen species (ROS) and enhance antioxidant capacity as an adaptation to intrinsic oxidative stress, suggesting that cancer cells are more vulnerable to oxidative insults and are more dependent on antioxidant systems compared with normal cells. Thus, disruption of redox homeostasis caused by a decline in antioxidant capacity may provide a method for the selective death of cancer cells. Here we show that ROS-mediated selective death of tumor cells can be caused by inhibiting sulfiredoxin (Srx), which reduces hyperoxidized peroxiredoxins, leading to their reactivation. Srx inhibitor increased the accumulation of sulfinic peroxiredoxins and ROS, which led to oxidative mitochondrial damage and caspase activation, resulting in the death of A549 human lung adenocarcinoma cells. Srx depletion also inhibited the growth of A549 cells like Srx inhibition, and the cytotoxic effects of Srx inhibitor were considerably reversed by Srx overexpression or antioxidants such as N-acetyl cysteine and butylated hydroxyanisol. Moreover, Srx inhibitor rendered tumorigenic ovarian cells more susceptible to ROS-mediated death compared with nontumorigenic cells and significantly suppressed the growth of A549 xenografts without acute toxicity. Our results suggest that Srx might serve as a novel therapeutic target for cancer treatment based on ROS-mediated cell death.
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Affiliation(s)
- Hojin Kim
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea
| | - Gong-Rak Lee
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea
| | - Jiwon Kim
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea
| | - Jin Young Baek
- College of Pharmacy, Ewha Womans University, Seoul 120-750, South Korea
| | - You-Jin Jo
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea
| | - Seong-Eun Hong
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea
| | - Sung Hoon Kim
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea
| | - Jiae Lee
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea
| | - Hye In Lee
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea
| | - Song-Kyu Park
- College of Pharmacy, Korea University, Sejong 339-700, South Korea
| | - Hwan Mook Kim
- College of Pharmacy, Gachon University of Medicine and Science, Incheon 406-799, South Korea
| | - Hwa Jeong Lee
- College of Pharmacy, Ewha Womans University, Seoul 120-750, South Korea
| | - Tong-Shin Chang
- College of Pharmacy, Ewha Womans University, Seoul 120-750, South Korea
| | - Sue Goo Rhee
- Yonsei Biomedical Research Institute, Yonsei University College of Medicine, Seoul 120-752, South Korea
| | - Ju-Seog Lee
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA
| | - Woojin Jeong
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 120-750, South Korea.
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Eom MJ, Kim K, Jo YJ, Yang JJ, Choi ES, Min BI, Park JH, Cheong SW, Kim JS. Dimerization-induced Fermi-surface reconstruction in IrTe2. Phys Rev Lett 2014; 113:266406. [PMID: 25615364 DOI: 10.1103/physrevlett.113.266406] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Indexed: 06/04/2023]
Abstract
We report a de Haas-van Alphen (dHvA) oscillation study on IrTe2 single crystals showing complex dimer formations. By comparing the angle dependence of dHvA oscillations with band structure calculations, we show distinct Fermi surface reconstruction induced by a 1/5-type and a 1/8-type dimerizations. This verifies that an intriguing quasi-two-dimensional conducting plane across the layers is induced by dimerization in both cases. A phase transition to the 1/8 phase with higher dimer density reveals that local instabilities associated with intra- and interdimer couplings are the main driving force for complex dimer formations in IrTe2.
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Affiliation(s)
- Man Jin Eom
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Kyoo Kim
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Y J Jo
- Department of Physics, Kyungpook National University, Daegu 702-701, Korea
| | - J J Yang
- Laboratory for Pohang Emergent Materials, Pohang University of Science and Technology, Pohang 790-784, Korea and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - E S Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - B I Min
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - J-H Park
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - S-W Cheong
- Laboratory for Pohang Emergent Materials, Pohang University of Science and Technology, Pohang 790-784, Korea and Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Piscataway, New Jersey 08854, USA
| | - Jun Sung Kim
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
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Jo YJ, Kim YH, Jo YH, Seong JG, Chang SY, Van Tyne CJ, Lee WH. Microporous Ti implant compact coated with hydroxyapatite produced by electro-discharge-sintering and electrostatic-spray-deposition. J Nanosci Nanotechnol 2014; 14:8439-8444. [PMID: 25958542 DOI: 10.1166/jnn.2014.9933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A single pulse of 1.5 kJ/0.7 g of atomized spherical Ti powder from 300 μF capacitor was applied to produce the porous-surfaced Ti implant compact by electro-discharge-sintering (EDS). A solid core surrounded by porous layer was self-consolidated by a discharge in the middle of the compact in 122 μsec. Average pore size, porosity, and compressive yield strength of EDS Ti compact were estimated to be about 68.2 μm, 25.5%, and 266.4 MPa, respectively. Coatings with hydroxyapatite (HAp) on the Ti compact were conducted by electrostatic-spray-deposition (ESD) method. As-deposited HAp coating was in the form of porous structure and consisted of HAp particles which were uniformly distributed on the Ti porous structure. By heat-treatment at 700 degrees C, HAp particles were agglomerated each other and melted to form a highly smooth and homogeneous HAp thin film consisted of equiaxed nano-scaled grains. Porous-surfaced Ti implant compacts coated with highly crystalline apatite phase were successfully obtained by using the EDS and ESD techniques.
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Jo YJ, Park J, Lee G, Eom MJ, Choi ES, Shim JH, Kang W, Kim JS. Valley-polarized interlayer conduction of anisotropic Dirac fermions in SrMnBi2. Phys Rev Lett 2014; 113:156602. [PMID: 25375728 DOI: 10.1103/physrevlett.113.156602] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Indexed: 06/04/2023]
Abstract
We report the valley-selective interlayer conduction of SrMnBi(2) under in-plane magnetic fields. The c-axis resistivity of SrMnBi(2) shows clear angular magnetoresistance oscillations indicating coherent interlayer conduction. Strong fourfold variation of the coherent peak in the c-axis resistivity reveals that the contribution of each Dirac valley is significantly modulated by the in-plane field orientation. This originates from anisotropic Dirac Fermi surfaces with strong disparity in the momentum-dependent interlayer coupling. Furthermore, we found a signature of broken valley symmetry at high magnetic fields. These findings demonstrate that a quasi-two-dimensional anisotropic Dirac system can host a valley-polarized interlayer current through magnetic valley control.
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Affiliation(s)
- Y J Jo
- Department of Physics, Kyungpook National University, Daegu 702-710, Korea
| | - Joonbum Park
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - G Lee
- Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Man Jin Eom
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - E S Choi
- National High Magnetic field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Ji Hoon Shim
- Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - W Kang
- Department of Physics, Ewha Womans University, Seoul 120-750, Korea
| | - Jun Sung Kim
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
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10
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Ok JM, Jo YJ, Kim K, Shishidou T, Choi ES, Noh HJ, Oguchi T, Min BI, Kim JS. Quantum oscillations of the metallic triangular-lattice antiferromagnet PdCrO2. Phys Rev Lett 2013; 111:176405. [PMID: 24206508 DOI: 10.1103/physrevlett.111.176405] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2013] [Revised: 07/15/2013] [Indexed: 06/02/2023]
Abstract
We report the electronic and transport properties of the triangular antiferromagnet PdCrO(2) at high magnetic fields up to 33 T, using measurements of the de Haas-van Alphen oscillations and the Hall resistivity. The de Haas-van Alphen oscillations below the magnetic ordering temperature T(N) reveal several two-dimensional Fermi surfaces of smaller size than those found in nonmagnetic PdCoO(2), consistent with the band structure calculations. This evidences Fermi surface reconstruction due to the 120° helical ordering of the localized Cr spins, suggesting significant coupling of the itinerant electrons to the underlying spin texture. This induces the nonlinear Hall resistivity at low temperatures via the magnetic breakdown in the reconstructed Fermi surface. Furthermore, such a coupling leads to the unconventional anomalous Hall effects near T(N) due to the field-induced spin chirality at high magnetic fields.
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Affiliation(s)
- Jong Mok Ok
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
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Oh SK, Song CG, Jang T, Kim KC, Jo YJ, Kwak JS. Reduction of gate leakage current on AlGaN/GaN high electron mobility transistors by electron-beam irradiation. J Nanosci Nanotechnol 2013; 13:1738-1740. [PMID: 23755582 DOI: 10.1166/jnn.2013.6987] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
This study examined the effect of electron-beam (E-beam) irradiation on the AIGaN/GaN HEMTs for the reduction of gate leakage. After E-beam irradiation, the gate leakage current significantly decreased from 2.68 x 10(-8) A to 4.69 x 10(-9) A at a drain voltage of 10 V. The maximum drain current density of the AIGaN/GaN HEMTs with E-beam irradiation increased 14%, and the threshold voltage exhibited a negative shift, when compared to that of the AIGaN/GaN HEMTs before E-beam irradiation. These results strongly suggest that the reduction of gate leakage current resulted from neutralization nitrogen vacancies and removing of oxygen impurities.
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Affiliation(s)
- S K Oh
- Department of Printed Electronics Engineering (WCU), Sunchon National University, Jeonnam 540-742, Korea
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12
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Hong CH, Jo YJ, Kim HA, Park MJ, Kwak JS. Improved electrical and optical properties of ITO/Ag/ITO films by using electron beam irradiation and their application to ultraviolet light-emitting diode as highly transparent p-type electrodes. J Nanosci Nanotechnol 2012; 12:4163-4167. [PMID: 22852364 DOI: 10.1166/jnn.2012.5934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We have investigated the effect of insertion of a Ag layer in ITO film as well as electron beam irradiation to the multilayer films on the electrical and optical properties of the ITO-based multilayer deposited by magnetron sputtering method at room temperature. Inserting a very thin Ag layer between ITO layers resulted in a significant decrease in sheet resistance and increased the optical band gap of the ITO/Ag/ITO multilayer to 4.35 eV, followed by a high transparency of approximately 80% at a wavelength of 375 nm. We have also fabricated ultraviolet light-emitting diodes (LED) by using the ITO/Ag/ITO p-type electrode with/without electron beam irradiation. The results show that the UV-LEDs having ITO/Ag/ITO p-electrode with electron beam irradiation produced 19% higher optical output power due to the low absorption of light in the p-type electrode.
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Affiliation(s)
- C H Hong
- Department of Printed Electronics Engineering (WCU), Sunchon National University, Jeonnam 540-742, Korea
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13
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Park J, Lee G, Wolff-Fabris F, Koh YY, Eom MJ, Kim YK, Farhan MA, Jo YJ, Kim C, Shim JH, Kim JS. Anisotropic Dirac fermions in a Bi square net of SrMnBi2. Phys Rev Lett 2011; 107:126402. [PMID: 22026779 DOI: 10.1103/physrevlett.107.126402] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Indexed: 05/31/2023]
Abstract
We report the observation of highly anisotropic Dirac fermions in a Bi square net of SrMnBi(2), based on a first-principles calculation, angle-resolved photoemission spectroscopy, and quantum oscillations for high-quality single crystals. We found that the Dirac dispersion is generally induced in the (SrBi)(+) layer containing a double-sized Bi square net. In contrast to the commonly observed isotropic Dirac cone, the Dirac cone in SrMnBi(2) is highly anisotropic with a large momentum-dependent disparity of Fermi velocities of ~8. These findings demonstrate that a Bi square net, a common building block of various layered pnictides, provides a new platform that hosts highly anisotropic Dirac fermions.
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Affiliation(s)
- Joonbum Park
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
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14
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Balicas L, Jo YJ, Shu GJ, Chou FC, Lee PA. Local moment, itinerancy, and deviation from Fermi-liquid behavior in NaxCoO2 for 0.71< or = x < or =0.84. Phys Rev Lett 2008; 100:126405. [PMID: 18517893 DOI: 10.1103/physrevlett.100.126405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Indexed: 05/26/2023]
Abstract
Here we report the observation of Fermi surface (FS) pockets via the Shubnikov-de Haas effect in NaxCoO2 for x=0.71 and 0.84, respectively. Our observations indicate that the FS expected for each compound intersects their corresponding Brillouin zones, as defined by the previously reported superlattice structures, leading to small reconstructed FS pockets, but only if a precise number of holes per unit cell is localized. For 0.71< or = x < 0.75 the coexistence of itinerant carriers and localized S=1/2 spins on a paramagnetic triangular superlattice leads at low temperatures to the observation of a deviation from standard Fermi-liquid behavior in the electrical transport and heat capacity properties, suggesting the formation of some kind of quantum spin-liquid ground state.
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Affiliation(s)
- L Balicas
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
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15
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Kang W, Osada T, Jo YJ, Kang H. Interlayer magnetoresistance of quasi-one-dimensional layered organic conductors. Phys Rev Lett 2007; 99:017002. [PMID: 17678182 DOI: 10.1103/physrevlett.99.017002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Indexed: 05/16/2023]
Abstract
We studied the interlayer magnetoresistance of the representative quasi-one-dimensional (Q1D) layered organic conductor, (TMTSF)2PF6, over the full range of magnetic field orientations in three dimensions, and constructed a stereographic conductivity plot. Our results show that the previously reported angular-dependent magnetoresistance phenomena in Q1D conductors are closely related to one another in intermediate field orientations. Based on a comparison with theories, we can conclude that the Lebed resonance is the only fundamental effect and that other effects result from the modulation of the Lebed resonance amplitude. Most of the observed phenomena can be explained within the framework of the conventional Fermi liquid; however, the anomalous enhancement of the interlayer conductivity under a field parallel to the conducting planes suggests the existence of a new electron state.
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Affiliation(s)
- W Kang
- Department of Physics, Ewha Womans University, Seoul, Korea.
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16
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Jo YJ, Balicas L, Capan C, Behnia K, Lejay P, Flouquet J, Mydosh JA, Schlottmann P. Field-induced Fermi surface reconstruction and adiabatic continuity between antiferromagnetism and the hidden-order state in URu2Si2. Phys Rev Lett 2007; 98:166404. [PMID: 17501440 DOI: 10.1103/physrevlett.98.166404] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Indexed: 05/15/2023]
Abstract
Shubnikov-de Haas oscillations reveal at high fields an abrupt reconstruction of the Fermi surface within the hidden-order (HO) phase of URu2Si2. Taken together with reported Hall effect results, this implies an increase in the effective carrier density and suggests that the field suppression of the HO state is ultimately related to destabilizing a gap in the spectrum of itinerant quasiparticles. While hydrostatic pressure favors antiferromagnetism in detriment to the HO state, it has a modest effect on the complex H-T phase diagram. Instead of phase separation between HO and antiferromagnetism our observations indicate adiabatic continuity between both orderings with field and pressure changing their relative weight.
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Affiliation(s)
- Y J Jo
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, USA
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17
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Balicas L, Analytis JG, Jo YJ, Storr K, Zandbergen H, Xin Y, Hussey NE, Chou FC, Lee PA. Shubnikov-de Haas effect in the metallic state of Na0.3CoO2. Phys Rev Lett 2006; 97:126401. [PMID: 17025986 DOI: 10.1103/physrevlett.97.126401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Indexed: 05/12/2023]
Abstract
Shubnikov-de Haas oscillations for two well-defined frequencies, corresponding, respectively, to areas of 0.8 and 1.36% of the first Brillouin zone, were observed in single crystals of Na(0.3)CoO2. The existence of Na superstructures in Na0.3CoO2, coupled with this observation, suggests the possibility that the periods are due to the reconstruction of the large Fermi surface around the Gamma point. An alternative interpretation in terms of the long sought-after epsilon'(g) pockets is also considered but found to be incompatible with existing specific heat data.
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Affiliation(s)
- L Balicas
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32306, USA
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18
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Choi ES, Brooks JS, Kang H, Jo YJ, Kang W. Resonant nernst effect in the metallic and field-induced spin density wave States of (TMTSF)2ClO4. Phys Rev Lett 2005; 95:187001. [PMID: 16383935 DOI: 10.1103/physrevlett.95.187001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2005] [Indexed: 05/05/2023]
Abstract
We examine an unusual phenomenon where, in tilted magnetic fields near magic angles parallel to crystallographic planes, a "giant" resonant Nernst signal has been observed by Wu et al. [Phys. Rev. Lett. 91, 056601 (2003)] in the metallic state of an organic conducting Bechgaard salt. We show that this effect appears to be a general feature of these materials and is also present in the field-induced spin density wave phase with even larger amplitude. Our results place conditions on any model that treats the metallic state as a state with finite Cooper pairing.
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Affiliation(s)
- E S Choi
- NHMFL/Physics, Florida State University, Tallahassee, Florida 32310, USA
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19
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Abstract
The purpose of this report is to document an unusual case of implant infection in a patient who had undergone enucleation and hydroxyapatite orbital implant surgery. A 32-year-old woman presented with chronic orbital discomfort and discharge following a history of hydroxyapatite orbital implant surgery at another hospital 4 years previous. She exhibited profuse discharge with a yellow, creamy color and marked conjunctival chemosis. Granulation tissue was noted on the central conjunctival surface. Following the removal of the conjunctival granulation tissue, a central 3x5 mm conjunctival dehiscence was present with exposure of the hydroxyapatite implant. A culture of purulent drainage emanating from the exposed implant showed a growth of Clostridium acetobutylicum. Removal of the orbital implant was done. The implant was noted to be filled with pus. This case suggests that anaerobic infection may be suspected when the granulation tissue is observed and a discharge with a foul odor is found.
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Affiliation(s)
- K S Park
- Department of Ophthalmology, School of Medicine, Chungnam National University, Taejeon, Korea
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20
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Lee J, Kang SU, Kim SY, Kim SE, Kang MK, Jo YJ, Kim S. Ester and hydroxamate analogues of methionyl and isoleucyl adenylates as inhibitors of methionyl-tRNA and isoleucyl-tRNA synthetases. Bioorg Med Chem Lett 2001; 11:961-4. [PMID: 11327600 DOI: 10.1016/s0960-894x(01)00095-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [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: 11/26/2022]
Abstract
The structure activity relationship on a series of ester and hydroxamate analogues of methionyl and isoleucyl adenylate has been investigated through introducing linkers between the 1'-position of ribose and adenine surrogates as methionyl-tRNA, and isoleucyl-tRNA synthetase inhibitors, respectively. The results indicate that ester analogue 23 was found to be a potent inhibitor of Escherichia coli methionyl-tRNA synthetase, and its interaction with the active site was proposed by a molecular modeling study.
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Affiliation(s)
- J Lee
- Laboratory of Medicinal Chemistry, College of Pharmacy, Seoul National University, Kwanak-Ku, South Korea.
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21
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Park SG, Jung KH, Lee JS, Jo YJ, Motegi H, Kim S, Shiba K. Precursor of pro-apoptotic cytokine modulates aminoacylation activity of tRNA synthetase. J Biol Chem 1999; 274:16673-6. [PMID: 10358004 DOI: 10.1074/jbc.274.24.16673] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [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: 11/06/2022] Open
Abstract
Endothelial monocyte activating polypeptide II (EMAPII) is a cytokine that is specifically induced by apoptosis. Its precursor (pro-EMAPII) has been suggested to be identical to p43, which is associated with the multi-tRNA synthetase complex. Herein, we have demonstrated that the N-terminal domain of pro-EMAPII interacts with the N-terminal extension of human cytoplasmic arginyl-tRNA synthetase (RRS) using genetic and immunoprecipitation analyses. Aminoacylation activity of RRS was enhanced about 2.5-fold by the interaction with pro-EMAPII but not with its N- or C-terminal domains alone. The N-terminal extension of RRS was not required for enzyme activity but did mediate activity stimulation by pro-EMAPII. Pro-EMAPII reduced the apparent Km of RRS to tRNA, whereas the kcat value remained unchanged. Therefore, the precursor of EMAPII is a multi-functional protein that assists aminoacylation in normal cells and releases the functional cytokine upon apoptosis.
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Affiliation(s)
- S G Park
- National Creative Research Initiatives Center for ARS Network, Sung Kyun Kwan University, Suwon, Kyunggido, 440-746, Korea
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22
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Abstract
Four stable analogues of methionyl adenylate (3-6) were designed as inhibitors of methionyl-tRNA synthetase and synthesized from 2',3'-isopropylideneadenosine. They strongly inhibited aminoacylation activity of methionyl-tRNA synthetases isolated from Escherichia coli, Mycobacterium tuberculosis, Saccharomyces cerevisiae and human. Among the microorganisms tested, however, these chemicals showed the growth inhibition effect only on E. coli.
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Affiliation(s)
- J Lee
- Laboratory of Medicinal Chemistry, College of Pharmacy, Seoul National University, Korea
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23
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Abstract
A series of methionine analogues have been synthesized as inhibitors of methionyl-tRNA synthetase and evaluated for their inhibitory activities of E. coli methionyl-tRNA synthetase and bacterial growth. Among them, L-methionine hydroxamate 20 has proved to be the best inhibitor of the enzyme with Ki = 19 microM and showed a growth inhibition against E.coli JM 109, P. vulganis 6059 and C. freundii 8090.
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Affiliation(s)
- J Lee
- Laboratory of Medicinal Chemistry, College of Pharmacy, Seoul National University, Korea
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24
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Abstract
A genomic sequence encoding mitochondrial methionyl-tRNA synthetase (MetRS) was determined from a pathogenic fungi Candida albicans. The gene is distinct from that encoding the cytoplasmic MetRS. The encoded protein consists of 577 amino acids (aa) and contains the class I defining sequences in the N-terminal domain and the conserved anticodon-binding amino acid, Trp, in the C-terminal domain. This protein showed the highest similarity with the mitochondrial MetRSs of Saccharomyces cerevisiae and Shizosaccharomyces pombe. The mitochondrial MetRSs of these fungi were distinguished from their cytoplasmic forms. The protein lacks the zinc binding motif in the N-terminal domain and the C-terminal dimerization appendix that are present in MetRSs of several other species. Escherichia coli tRNAMet was a substrate for the encoded protein as determined by genetic complementation and in vitro aminoacylation reaction. This cross-species aminoacylation activity suggests the conservation of interaction mode between tRNAMet and MetRS.
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Affiliation(s)
- S W Lee
- Department of Biology, Sung Kyun Kwan University, 300 Chunchundong, Jangangu, Suwon, Kyunggido 440-746, South Korea
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25
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Kim S, Jo YJ, Lee SH, Motegi H, Shiba K, Sassanfar M, Martinis SA. Biochemical and phylogenetic analyses of methionyl-tRNA synthetase isolated from a pathogenic microorganism, Mycobacterium tuberculosis. FEBS Lett 1998; 427:259-62. [PMID: 9607323 DOI: 10.1016/s0014-5793(98)00417-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mycobacterium tuberculosis methionyl-tRNA synthetase (MetRS) has been cloned and characterized. The protein contains class I signature sequences but lacks the Zn2+ binding motif and the C-terminal dimerization appendix that are found in MetRSs from several organisms including E. coli MetRS. Consistent with these features, the enzyme behaved as a monomer in a gel filtration chromatography and did not contain the bound Zn2+. Nonetheless, it was active to the tRNAMet of E. coli as determined by in vivo genetic complementation and in vitro reaction. Phylogenetic analysis separated the M. tuberculosis and E. coli MetRSs into prokaryote and eukaryote-archaea group, respectively. This result is consistent with the taxonomic locations of the organism but is an interesting contrast to the case of its paralogous protein, isoleucyl-tRNA synthetase, and suggests that the two enzymes evolved in separate idiosyncratic pathways.
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Affiliation(s)
- S Kim
- Sung Kyun Kwan University, Department of Biology, Suwon, Kyunggido, South Korea.
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26
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Abstract
Aminoacyl-tRNA synthetases (tRNA synthetases) of higher eukaryotes form a multiprotein complex. Sequence elements that are responsible for the protein assembly were searched by using a yeast two-hybrid system. Human cytoplasmic isoleucyl-tRNA synthetase is a component of the multi-tRNA synthetase complex and it contains a unique C-terminal appendix. This part of the protein was used as bait to identify an interacting protein from a HeLa cDNA library. The selected sequence represented the internal 317 amino acids of human bifunctional (glutamyl- and prolyl-) tRNA synthetase, which is also known to be a component of the complex. Both the C-terminal appendix of the isoleucyl-tRNA synthetase and the internal region of bifunctional tRNA synthetase comprise repeating sequence units, two repeats of about 90 amino acids, and three repeats of 57 amino acids, respectively. Each repeated motif of the two proteins was responsible for the interaction, but the stronger interaction was shown by the native structures containing multiple motifs. Interestingly, the N-terminal extension of human glycyl-tRNA synthetase containing a single motif homologous to those in the bifunctional tRNA synthetase also interacted with the C-terminal motif of the isoleucyl-tRNA synthetase although the enzyme is not a component of the complex. The data indicate that the multiplicity of the binding motif in the tRNA synthetases is necessary for enhancing the interaction strength and may be one of the determining factors for the tRNA synthetases to be involved in the formation of the multi-tRNA synthetase complex.
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Affiliation(s)
- S B Rho
- Department of Biology, Sung Kyun Kwan University, Suwon, Kyunggido, South Korea
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