• Journal of Photoscience
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• 제12권3호
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• pp.129-133
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• 2005

The psbC gene, encoding the intrinsic chlorophyll-binding protein of CP43, one of the PS core complex polypeptides, was cloned from the Panax ginseng chloroplast, which is composed of 1,422 nucleotides and the overall nucleotide sequence shows more than 84% identity to those of eukaryotic photosynthetic organisms. The predicted topology of CP43, based on hydropathy analysis, includes six membrane-spanning ${\alpha}-helices$ resulting in three lumenal and four stromal loops. The putative translation start codon for the psbC gene is located at 48 nucleotides upstream from the stop codon of the psbD gene whose product is also a component of the PSII reaction center, implying that the promoter of the psbC gene is possibly located in the middle of the structural gene of the psbD gene. Northern blot analysis of the in vivo accumulation of the psbC transcript from the plants grown under the various growth light intensities (5%, 10%, 20%, and 100%) of daylight indicated that the steady-state level of the psbC transcript was not significantly affected by light intensity.

• Fisheries and Aquatic Sciences
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• 제20권9호
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• pp.23.1-23.9
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• 2017

Two distinct cDNAs encoding aquaporins (mmAQPs 1a and 3a) were isolated and characterized from mud loach Misgurnus mizolepis. The identified mud loach AQP cDNAs encode for polypeptides of 260 and 302 amino acids. Topology predictions confirmed six putative membrane-spanning domains connected by five loops and the N- and C-terminal domains being cytoplasmic. The mud loach AQPs 1a and 3a showed broad distribution in multiple tissues including immune-responsive tissues as well as osmoregulatory tissues. Hence, the diversity of AQP distribution and expression possibly indicated its differential functions in the regulation of fluid movement in response to environmental stimuli. The transcription of mmAQP genes was differentially modulated by immune challenges. In particular, the mmAQP3a expression level in the liver was more responsive to immune challenges than that of mmAQP1a. Taken together, fish stimulation or infection resulted in significant modulation of mud loach AQP genes, suggesting potential functional roles of these proteins in piscine pathophysiological process.

• Bulletin of the Korean Chemical Society
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• 제30권3호
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• pp.623-629
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• 2009

We have performed replica-exchange molecular dynamics simulations on 41 residue peptide mainly composed of NAC (non A$\beta$ component) sequence in $\alpha$-Synuclein. To investigate conformational characteristics of intrinsically unstructured peptides, we carried out structural analysis on the ‘representative structures’ for ensemble of structures occurring at different temperatures. The secondary structure profile obtained from our simulations suggests that the NAC region of $\alpha$-synuclein can be divided into roughly three helical-like segments. It is found that the overall helix-turn-helix like topology is conserved even though the conformational fluctuations grow as the temperature increases. The coordinate-based and the distance-based representative structures exhibit noticeable differences at higher temperatures while they are similar at lower temperatures. It is found that structural variations for the coordinate-based representative structures are much larger, suggesting that distance-based representative structures provide more reliable information concerning characteristic features of intrinsically unstructured proteins. The present analysis also indicates that the conformational features of representative structures at high temperatures might be related to those in membrane or low pH environment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 춘계학술대회 논문집 에너지변화시스템부문
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• pp.266-268
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• 2009

In this paper, authors deal with a power conditioning system (PCS) of high efficiency for a proton exchange membrane fuel cell (PEMFC) generation system. Fuel cells are a direct current (DC) power generators. They generate electricity through an electrochemical process that converts the energy stored in a fuel directly into electricity. Fuel cells have many benefits, which produce no particulate matter, nitrogen or sulfur oxides. And they have few moving parts and produce little or no noise. When fueled by hydrogen, they yield only heat and water as byproducts. Their wide application can reduce our dependence on fossil fuels and foreign sources of petroleum. This paper studies on a novel PCS circuit topology of high efficiency using in PEMFC generation system The controlling switches in the PCS is operated to soft switching. Some digital simulation results and experimental results for the proposed PCS is confirmed to the validity of the analytical results.

• BMB Reports
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• 제53권5호
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• pp.260-265
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• 2020

Scorpion venom comprises a cocktail of toxins that have proven to be useful molecular tools for studying the pharmacological properties of membrane ion channels. HelaTx1, a short peptide neurotoxin isolated recently from the venom of the scorpion Heterometrus laoticus, is a 25 amino acid peptide with two disulfide bonds that shares low sequence homology with other scorpion toxins. HelaTx1 effectively decreases the amplitude of the K⁺ currents of voltage-gated Kv1.1 and Kv1.6 channels expressed in Xenopus oocytes, and was identified as the first toxin member of the κ-KTx5 subfamily, based on a sequence comparison and phylogenetic analysis. In the present study, we report the NMR solution structure of HelaTx1, and the major interaction points for its binding to voltage-gated Kv1.1 channels. The NMR results indicate that HelaTx1 adopts a helix-loop-helix fold linked by two disulfide bonds without any β-sheets, resembling the molecular folding of other cysteine-stabilized helix-loop-helix (Cs α/α) scorpion toxins such as κ-hefutoxin, HeTx, and OmTx, as well as conotoxin pl14a. A series of alanine-scanning analogs revealed a broad surface on the toxin molecule largely comprising positively-charged residues that is crucial for interaction with voltage-gated Kv1.1 channels. Interestingly, the functional dyad, a key molecular determinant for activity against voltage-gated potassium channels in other toxins, is not present in HelaTx1.

• Transactions on Electrical and Electronic Materials
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• 제17권2호
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• pp.57-68
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• 2016

In this study, we present the modern hybrid system based power generation for electric vehicle applications. We describe the hybrid structure of modified current source based DC - DC converters used to extract the maximum power from Photovoltaic (PV) and Fuel Cell system. Due to reduced dc-link capacitor requirement and higher reliability, the current source inverters (CSI) better compared to the voltage source based inverter. The novel control strategy includes Distributed Maximum Power Point Tracking (DMPPT) for photovoltaic (PV) and fuel cell power generation system. The proposed DC - DC converters have been analyzed in both buck and boost mode of operation under duty cycle 0.5>d, 0.5<d<1 and 0.5<d for capable electric vehicle applications. The proposed topology benefits include one common DC-AC inverter that interposes the generated power to supply the charge for the sharing of load in a system of hybrid supply with photovoltaic panels and fuel cell PEM. An improved control of Direct Torque and Flux Control (DTFC) based induction motor fed by current source converters for electric vehicle.In order to achieve better performance in terms of speed, power and miles per gallon for the expert, to accepting high regenerative braking current as well as persistent high dynamics driving performance is required. A simulation model for the hybrid power generation system based electric vehicle has been developed by using MATLAB/Simulink. The Direct Torque and Flux Control (DTFC) is planned using Xilinx ISE software tool in addition to a Modelsim 6.3 software tool that is used for simulation purposes. The FPGA based pulse generation is used to control the induction motor for electric vehicle applications. FPGA has been implemented, in order to verify the minimal error between the simulation results of MATLAB/Simulink and experimental results.

• Molecules and Cells
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• 제39권6호
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• pp.495-500
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• 2016

We have solved the crystal structure of a predicted fructose-specific enzyme $IIB^{fruc}$ from Escherichia coli ($EcEIIB^{fruc}$) involved in the phosphoenolpyruvate-carbohydrate phosphotransferase system transferring carbohydrates across the cytoplasmic membrane. $EcEIIB^{fruc}$ belongs to a sequence family with more than 5,000 sequence homologues with 25-99% amino-acid sequence identity. It reveals a conventional Rossmann-like ${\alpha}-{\beta}-{\alpha}$ sandwich fold with a unique ${\beta}$-sheet topology. Its C-terminus is longer than its closest relatives and forms an additional ${\beta}$-strand whereas the shorter C-terminus is random coil in the relatives. Interestingly, its core structure is similar to that of enzyme $IIB^{cellobiose}$ from E. coli ($EcIIB^{cel}$) transferring a phosphate moiety. In the active site of the closest $EcEIIB^{fruc}$ homologues, a unique motif CXXGXAHT comprising a P-loop like architecture including a histidine residue is found. The conserved cysteine on this loop may be deprotonated to act as a nucleophile similar to that of $EcIIB^{cel}$. The conserved histidine residue is presumed to bind the negatively charged phosphate. Therefore, we propose that the catalytic mechanism of $EcEIIB^{fruc}$ is similar to that of $EcIIB^{cel}$ transferring phosphoryl moiety to a specific carbohydrate.

• 생명과학회지
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• 제26권3호
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• pp.275-281
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• 2016

인체치료용 당단백질은 바이오의약품에 있어서 중요한 요소이며 특히, 단백질 말단에 결합되어있는 시알산은 의약품의 체내 활성이나 안정성에 큰 영향을 미친다. 최근 돼지유즙은 바이오의약품을 생산하기 위한 생체반응기로써 주목받고 있다. β-1,4-N-acetylglucosaminyltransferase A (MGAT4A)는 재조합단백질이 가지는 시알산 함량을 늘리기 위한 필수 효소 중 하나이다. 그러나 돼지 MGAT4A는 아직도 그 서열이나 기능이 불분명하다. 따라서 이번 연구에서는 돼지 MGAT4A의 서열 동정 및 기능분석을 하였다. 돼지 MGAT4A는 535개의 아미노산을 코딩하는 1,638개의 염기서열로 이루어져 있으며, 일반적인 당전이효소들의 특징인 type II membrane topology의 특성을 가지고 있다. Real-time PCR분석법을 통하여, 지금까지 알려진 것과는 조금 다르게 MGAT4A 유전자가 간이나 유선에서 많은 발현을 보였으나 소장이나 위, 방광에서는 그 발현량이 적다는 것도 확인하였다. 또한, 효소의 기능 분석을 위하여 PK-15 세포주에서 MGAT4A효소의 과발현을 유도하였다. 과발현이 확인된 세포주로 렉틴을 이용한 면역형광염색법과 ELISA방법으로 MGAT4A효소의 과발현이 β-1,4-N-acetylglucosamine의 함량을 증가시켰음을 확인하였다. 또한 기질반응을 통해 bi-antennary structure에 대한 반응성도 확인하였으며, MGAT4A의 과발현이 유도된 세포에서 약 3배 이상의 높은 기질 반응성을 보였다. 이러한 연구는 생체반응기로써 돼지를 이용하는데 있어서 중요한 기반이 될 것이라고 생각한다.