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Chemical Modification of Brain Glutamate Dehydrogenase Isoproteins with Phenylglyoxal
Ahn, Jee-Yin,Cho, Eun-Hee,Lee, Kil-Soo,Choi, Soo-Young,Cho, Sung-Woo Korean Society for Biochemistry and Molecular Biol 1999 Journal of biochemistry and molecular biology Vol.32 No.5
Incubation of two types of glutamate dehydrogenase isoproteins from bovine brain with the arginine-specific dicarbonyl reagent phenylglyoxal resulted in a biphasic loss of enzyme activity. Reaction of the glutamate dehydrogenase isoproteins with phenylglyoxal caused a rapid loss of 53~62% of the enzyme activities and modification of two residues of arginine per enzyme subunit. Prolonged incubation of the glutamate dehydrogenase isoproteins with phenylglyoxal resulted in the modification of an additional four residues of arginine per enzyme subunit without further loss of the residual activities. Partial protection against inactivation was provided by the coenzyme NADH or substrate 2-oxoglutarate. The most marked decrease in the rate of inactivation was observed by the combined addition of NADH and 2-oxoglutarate, suggesting that the first two modified arginine residues are in the vicinity of the catalytic site. However, inactivation of the glutamate dehydrogenase isoproteins by phenylglyoxal appears to be partial with approximately 40% activity remained after an extended reaction time with excess reagent, suggesting that the modified arginine residues may not be directly involved in catalysis. The lack of complete protection by substrates also suggest the possibility that the modified arginine residues are not directly involved at the active site, and the partial loss of activity by the modification of arginine residues may be due to a conformational change. There were no significant differences between the two glutamate dehydrogenase isoproteins in sensitivities to inactivation by phenylglyoxal, indicating that the microenvironmental structures of the glutamate dehydrogenase isoproteins are very similar to each other.
HEV용 리튬이온 배터리의 양극물질로 사용되는 LiMn₂O₄의 용량에 대한 입자크기의 효과
지미정(Jee, Mi-Jung),최병현(Choi, Byung-Hyun),이대진(Lee, Dae-Jin),위인루(Wai, Yin-Loo),배현(Bae, Hyun) 한국신재생에너지학회 2007 한국신재생에너지학회 학술대회논문집 Vol.2007 No.11
HEV용 리튬이온 전지에 대한 연구는 최근에 많은 연구가 진행되고 있으며 그중 고용량 및 저렴한 가격, 환경에 대한 안정성으로 인해 Li-Mn spinel에 대한 성능향상 연구가 많이 이루어지고 있다. 본 연구에서는 Li-Mn spinel의 입자크기에 대한 기초 물성 과 전기적 특성을 측정하여 입자크기가 용량에 미치는 영향에 대한 고찰을 하였다. Li-Mn spinel의 비표면적, C-V 특성, 전기적 용량, coulomb efficiency 등을 통하여 입자의 크기와 전해액, Li의 구동등과 관련하여 용량특성에 향상을 가져오는 입자크기 조건을 정의하였고 그에 따라 온도별로 합성 한 후 입자사이즈에 대한 특성을 나타내었다.
HEV용 리튬 이차전지 양극물질 LiMn₂O₄에 Li₄Ti<SUB>5</SUB>O<SUB>12</SUB>코팅에 따른 영향
위인루(Wai, Yin-Loo),최병현(Choi, Byung-Hyun),지미정(Jee, Mi-Jung),이대진(Lee, Dae-Jin),신재수(Shin, Jae-Su),송광호(Song, Kwang-Ho) 한국신재생에너지학회 2007 한국신재생에너지학회 학술대회논문집 Vol.2007 No.11
In these recent years, low cost and stable battery electrode materials have been studied for HV/HEV application. Spinel cathode material LiMn₂O₄ is widely studied as a promising cathode material of lithium ion secondary batteries because of it is low cost, easily to be prepared and capable to be operated in high voltage range. In this study, LiMn₂O₄ was undergoing surface modification with spinel lithium titanium oxide by sol-gel method in order to enhance its capacity retention. Properties of both unmodified and surface-modified LiMn₂O₄ were characterized by XRD, SEM, particle size analyzer while their cycling performance was tested with charge and discharge tester.
CHO, SUNG-WOO,AHN, JEE-YIN,BAHN, JAE HOON,JEON, SEONG GYU,PARK JINSEU,LEE, KIL SOO,CHOI, SOO YOUNG 한국미생물 · 생명공학회 2000 Journal of microbiology and biotechnology Vol.10 No.5
Monoclonal antibodies against glutamate dehydrogenase (GDH) from Sulfolobus solfataricus were produced and characterized using epitope mapping and biosensor technology. Five monoclonal antibodies raised against S. solfataricus GDH were each identified as a single protein band that comigrated with purified S. solfataricus GDH on the SDS-polyacrylamide gel electrophoresis and immunoblot. Epitope mapping analysis showed that only one subgroup among the antibodies tested recognized the same peptide fragments of GDH. Using the anti-S. solfataricus GDH antibodies as probes, the cross-reactivities of GDHs from various sources were investigated and it was found that the mammalian GDH is not immunologically related to S. solfataricus GDH. The structural differences between the microbial and mammalian GDHs were further investigated using biosensor technology (Pharmacia BlAcore) and monoclonal antibodies against S. solfataricus and bovine brain. The binding affinity of S. solfataricus glutamate dehydrogenase anti-S. solfataricus for GDH (K_D=11nM) was much tighter than that of anti-bovine for GDH (K_D=450nM). These results, together with the epitope mapping analysis, suggest that there may be structural differences between the two GDH species, in addition to their different biochemical properties.
Chemical Modification of Brain Glutamate Dehydrogenase Isoproteins with Phenylglyoxal
Cho, Sung-Woo,Ahn, Jee-Yin,Cho, Eun-Hee,Lee, Kil-Soo,Choi, Soo-Young The Korea Science and Technology Center 1999 BMB Reports Vol.32 No.5
Incubation of two types of glutamate dehydrogenase isoproteins from bovine brain with the arginine-specific dicarbonyl reagent phenylglyoxal resulted in a biphasic loss of enzyme activity. Reaction of the glutamate dehydrogenase isoproteins with phenylglyoxal caused a rapid loss of 53∼62% of the enzyme activities and modification of two residues of arginine per enzyme subunit. Prolonged incubation of the glutamate dyhydrogenase isoproteins with phenylglyoxal resulted in the modification of an additional four residues of arginine per enzyme subunit without further loss of the residual activities. Partial protection against inactivation was provided by the coenzyme NADH or substrate 2-oxoglutarate. The most marked decreased in the rate of inactivation was observed by the combined addition of NADH and 2-oxoglutarate, suggesting that the first two modified arginine residues are in the vicinity of the catalytic site. However, inactivation of the glutamate dehydrogenase isoproteins by phenylglyoxal appears to be partial with approximately 40% activity remained after an extended reaction time with excess reagent, suggesting that the modified arginine residues may not be directly involved in catalysis. The lack of complete protection by substrates also suggest the possibility that the modified arginine residues are not directly involved at the active site, and the partial loss of activity by the modification of arginine residues may be due to a conformational change. There were no significant differences between the two glutamate dehydrogenase isoproteins in sensitivities to inactivation by phenylglyoxal, indicating that the microenvironmental structures of the glutamate dehydrogenase isoproteins are very similar to each other.
Suppression of Lipopolysaccharide-Induced Microglial Activation by a Benzothiazole Derivative
Kim, Eun-A,Kim, Han-Wook,Ahn, Jee-Yin,Hahn, Hoh-Gyu,Kim, Key-Sun,Kim, Tae-Ue,Cho, Sung-Woo Korean Society for Molecular and Cellular Biology 2010 Molecules and cells Vol.30 No.1
We previously reported that KHG21834, a benzothiazole derivative, attenuates the beta-amyloid (A${\beta}$)-induced degeneration of both cortical and mesencephalic neurons in vitro. Central nervous system inflammation mediated by activated microglia is a key event in the development of neurodegenerative disease. In this study, we show that KHG21834 suppresses inflammation-mediated cytokine upregulation. Specifically, KHG21834 induces significant reductions in the lipopolysaccharide-induced activation of microglia and production of proinflammatory mediators such as tumor necrosis factor-${\alpha}$, interlukin-1${\beta}$, nitric oxide, and inducible nitric oxide synthase. In addition, KHG21834 blocks the expression of mitogen-activated protein kinases, including ERK, p38 MAPK, JNK, and Akt. In vivo intracerebroventricular infusion of KHG21834 also leads to decreases the level of interleukin-1${\beta}$ and tumor necrosis factor-${\alpha}$ in brain. These results, in combination with our previous findings on A${\beta}$-induced degeneration, support the potential therapeutic efficacy of KHG21834 for the treatment of neurodegenerative disorders via the targeting of key glial activation pathways.
Le Xuan Nguyen, Truong,Ahn, Jee-Yin Korean Society for Biochemistry and Molecular Biol 2007 Journal of biochemistry and molecular biology Vol.40 No.6
Src homology (SH) domains of phospholipase C-$\gamma1$ (PLC-$\gamma1$) impair NGF-mediated PC12 cells differentiation. However, whether the enzymatic activity is also implicated in this process remains elusive. Here, we report that the enzymatic activity of phospholipase C-$\gamma1$ (PLC-$\gamma1$) is at least partially involved to the blockage of neuronal differentiation via an abrogation of MAPK activation, as well as sustained Akt activation. By contrast, Overexpression of WT-PLC-$\gamma1$ exhibited sustained NGF-induced MAPK activation, and triggered transient Akt activation resulting in profound inhibition of neurite outgrowth. However, lipase-inactive mutant (LIM) PLC-$\gamma1$ cells fail to suppress neurite outgrowth, although it contains intact SH domains, specifically enhancing the expression of cyclin D1 and p21 proteins, which regulate the function of retinoblastoma Rb protein. These observations show that the lipase inactive mutant of PLC-$\gamma1$ does not alter NGF-induced neuronal differentiation via enzymatic inability and the modulation of cell cycle regulatory proteins independent on SH3 domain.