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Structural Insights into the Regulation of ACC2 by Citrate
권성중,조영순,허용석 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.2
Acetyl-CoA carboxylases (ACCs) play critical roles in fatty acid synthesis and oxidation by the catalytic activity of the carboxylation of acetyl-CoA to malonyl-CoA. It is known that ACCs are inactivated through reversible phosphorylation by AMP-activated protein kinase (AMPK) and allosterically activated by citrate. Here, we determined the crystal structures of biotin carboxylase (BC) domain of human ACC2 phosphorylated by AMPK in the presence of citrate in order to elucidate the activation mechanism by citrate. This structure shows that phosphorylated Ser222 is released from the dimer interface, and thereby facilitating the dimerization or oligomerization of the BC domain allosterically. This structural explanation is coincident with the experimental result that the phosphorylated Ser222 was dephosphorylated more easily by protein phosphatase 2A (PP2A) as the citrate concentration increases.
박승영,김기준,권성중 대한화학회 2024 Bulletin of the Korean Chemical Society Vol.45 No.1
Ammonia borane (AB) has garnered significant attention as a high‐efficiency energy source, prompting extensive investigations into its electrochemical oxidation. One prominent avenue of research focuses on the development of electrocatalysts to enhance the oxidation of AB. Employing the novel approach of single‐entity electrochemistry (SEE), the electrocatalytic properties of gold (Au), silver (Ag), and palladium (Pd) nanoparticles (NPs) for AB oxidation were explored. In the case of Au and Ag NPs, SEE experiments yielded no discernible current signal, in contrast to the electrocatalytic currents observed with bulk electrodes. However, when Pd NPs were utilized, characteristic staircase signals in the SEE measurements were observed. The variation of the SEE current signal for Pd NPs under different applied potentials, AB concentrations, and NP concentrations was further investigated. An analysis of the SEE signal elucidated the conditions under which Pd NPs can effectively catalyze AB oxidation at the single NP level. Ammonia borane (AB) has garnered significant attention as a high-efficiency energy source, prompting extensive investigations into its electrochemical oxidation. One prominent avenue of research focuses on the development of electrocatalysts to enhance the oxidation of AB. Employing the novel approach of single-entity electrochemistry (SEE), the electrocatalytic properties of gold (Au), silver (Ag), and palladium (Pd) nanoparticles (NPs) for AB oxidation were explored. In the case of Au and Ag NPs, SEE experiments yielded no discernible current signal, in contrast to the electrocatalytic currents observed with bulk electrodes. However, when Pd NPs were utilized, characteristic staircase signals in the SEE measurements were observed. The variation of the SEE current signal for Pd NPs under different applied potentials, AB concentrations, and NP concentrations was further investigated. An analysis of the SEE signal elucidated the conditions under which Pd NPs can effectively catalyze AB oxidation at the single NP level.
Detection of Single Au Nanoparticle Collisions Using Electrocatalytic Amplification Method
김동영,이상민,권성중 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.2
Detection of single gold (Au) nanoparticle (NP) collisions on a carbon-fiber (C-fiber) ultramicroelectrode (UME) was carried out successfully using the electrocatalytic amplification method. The C-fiber UME shows a low and quite stable background current for the hydrazine oxidation over a wide potential range. The electrocatalytic current transient generated by Au NP collision on the C-fiber UME was also detected simultaneously without any pretreatment of the UME or deformation of the Au NP. The magnitude and frequency of the transient current from Au NP collisions agree well with the calculated values based on the size and concentration of the Au NP.
산화 이리듐의 물의 산화반응에 대한 버블 과전압 현상과 촉매 특성 연구
김정중,최용수,권성중,Kim, Jeong Joong,Choi, Yong Soo,Kwon, Seong Jung 한국전기화학회 2013 한국전기화학회지 Vol.16 No.2
Iridium oxide is well known as an electrocatalyst for the water oxidation. Recently, Dr. Bard's group observed the electrocatalytic behavior of individual nanoparticle of Iridium oxide using the electrochemical amplification method by detecting the single nanoparticle collisions at the ultramicroelectrode (UME). However, the electrocatalytic current is decayed as a function of time. In this study, we investigated that the reason of electrocatalytic current decay of water oxidation at Iridium oxide nanoparticles. We identified it is due to the bubble overpotential because the cyclic current decay and recovery were synchronized to the oxygen bubble growth and coming away from an Iridium disk electrode. 산화 이리듐은 물의 산화반응에 대해 좋은 전기촉매 물질로서 많은 연구가 이루어 지고 있다. 최근 전기화학적 증폭방법을 이용하여 산화 이리듐 나노입자의 개별적인 촉매특성을 연구한 결과를 보면 촉매반응에 의한 전류가 지속적으로 유지되지 않고 시간에 따라 감소하는 결과가 얻어 졌다. 이러한 촉매특성의 사라짐에 대한 원인을 규명하고자 사이즈가 큰 이리듐전극을 산화시킨 산화이리듐 전극에서 물의 산화반응을 진행시켰다. 그 결과 나노입자에서와 유사하게 전류가 감소하는 현상이 관찰되었다. 큰 전극에서의 실험에서는 발생하는 산소방울을 관찰 할 수 있었는데 산소방울의 발생 주기가 전류의 증감주기와 일치하는 것으로 보아 전류의 감소는 산소방울에 의한 버블 과전압 때문으로 생각된다.
김기준,송예솔,박승영,오승준,권성중 대한화학회 2023 Bulletin of the Korean Chemical Society Vol.44 No.2
The concentration of human immunoglobulin E (IgE) in blood is an indicatorfor diagnosing an allergy. For detecting human IgE by an electrochemicalimmunosensor, redox mediator molecules were modified on a gold electrodeusing thiolated organic molecules, which can form self-assembled monolayerson the electrode surface. Ferrocene was used as a redox mediator, and the cur-rent signal was amplified via redox cycling using 4-aminophenol. Measure-ments were obtained after the immobilization of the target-captured antibody,target human IgE, biotin-conjugated secondary antibody, and avidin alkalinephosphatase in a sandwich-type immunosensor configuration. The preparedimmunosensor exhibited a limit of detection of 1 IU/mL and dynamic range of3–30 IU/mL.