• BMB Reports
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• 제29권3호
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• pp.210-214
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• 1996

The pH dependence of the kinetic parameters of mutant O-acetylserine sulfhydrylase (OASS) from Salmonella typhimurium LT-2 has been determined in order to obtain information on the chemical mechanism. The initial velocity pattern obtained by varying the concentrations of OAS at several fixed concentrations of TNB, shows an intersection on the left of the ordinate at pH 7.0, indicating that the kinetic mechanism is a sequential mechanism in which substrate inhibition by OAS is observed while the wild type enzyme showed a ping pong mechanism. The values of $V/E_t$, $V/K_{OAS}E_{t}$ and $V/K_{TNB}E_{t}$ decreased by about 68%, 14% and 16% as compared with the wild type enzyme. The $V/K_{OAS}E_{t}$ is a pK of 6.5 on the acid side of the pH profile, and the $V/K_{TNB}$ is pH independent. As compared with the wild type enzyme, the pKs in the V/K profiles are shifted, reflecting that binding of the cofactor in free E:OAS is less asymmetric.

• 대한화학회지
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• 제62권5호
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• pp.412-416
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• 2018

• Biomolecules & Therapeutics
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• 제2권1호
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• pp.28-33
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• 1994

In order to obtain insight into the repair mechanism of DNA containing thymine photo-dimer, the conformation of the duplex d(GCGGTTGGCG).d(CGCCAACCGC) with a thymine dimer incorporated has been studied by proton NMR. NOE data show that, although the local environment around the thymine dimer is altered, the gross structural changes are relatively small. T$_4$endonuclease V exhibited a conformational change on complex formation with DNA. This conformational change occurred around histidine 16 which was close to tyrosine 129 located in the aromatic segment (WYKYY) near the C-terminus. It is likely that the interaction between T$_4$endonuclease V and DNA is strong since the complex was not dissociated up to 1.6 M NaCl.

• Journal of Microbiology and Biotechnology
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• 제14권5호
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• pp.891-900
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• 2004

UDP-N-Acetylglucosamine(GlcNAc):$\beta$1,4-D-mannoside$\beta$-l ,4N-acetylglucosaminyltransferase-III (GnT-III) and UDP-N-GlcNAc:$\alpha$-6-D-mannosid$\beta$-1,6N-acetylglucosaminyltransferase-V(GnT - V) activities were determined in human hepatoma cell lines and metastatic colon cancer cells, and their activities were compared with those of normal liver cells and fetal hepatocytes. GnT-III activities were higher than those of GnT-V in hepatic carcinoma cells. When the two enzyme activities were assayed in highly metastatic colon cancer cells, GnT - V activities were much higher than those of GnT-III. When GlcN, GlcN-biant-PA and UDP-GlcNAc were used as substrates, the enzymes displayed different kinetic properties between hepatic and colon cancer cells, depending on their metastatic potentials. Normal cells of two origins had characteristically very low levels of GnT-III and -V activities, whereas hepatoma and colon cancer cells contained high levels of activities. These data were supported by RT-PCR and Northern blot analyses, showing that the expression of GnT-III and -V mRNAs were increased in proportion to the enzymatic activities. The increased GnT-III, md -V activities were also correlated with increased glycosylation of the cellular glycoproteins in hepatoma and colon cancer cells, as examined by lectin blotting analysis by using wheat germ glutinin (WGA), erythroagglutinating phytohemagglutinin (E-PHA), leukoagglutinating phytohemagglutinin (L-PHA), and concanavalin A (Con A). Treatment with retinoic acid, a differentiation agent, resulted in decreases of both GnT-III and -V activities of HepG2 and HepG3 cells. In colon carcinoma cells, however, treatment with retinoic acid resulted in a reduction of GnT-V activity, but not with GnT-III activity. Although the mechanism underlying the induction of these mzymes is unclear, oligosaccharides in many glycoproteins have been observed of cancer cells.

• 정보보호학회논문지
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• 제31권5호
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• pp.889-899
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• 2021

본 논문은 블록체인 기술에서 탈중앙화된 시스템 접근 방식을 활용하여 차량 인터넷(IoV)에서 신뢰할 수 있는 데이터 공유 체계를 제안한다. 스마트 계약에 기초한 인센티브 메커니즘을 채택하여, 차량은 올바른 교통 정보 메시지를 정직하게 공유함으로써 시스템으로부터 특정한 보상을 받게 된다. 이후 차량은 평판 등급을 생성하여 수신되는 모든 정보 메세지를 검증함으로서 메시지에 대한 신뢰성을 유지한다. 한편 네트워크 성능을 분석하기 위해 이산 이벤트 시뮬레이터를 사용하여 IoT 네트워크를 시뮬레이션하였고, 인센티브 모델은 분산형 접근 방식의 이더리움 스마트 계약을 활용하여 설계하였다.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2019년도 추계학술대회
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• pp.8-8
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• 2019

The stringent response (SR) is characterized as a bacterial defense mechanism in response to various growth-inhibiting stresses. It is activated by accumulation of a small nucleotide regulator, (p)ppGpp, and induces global changes in bacterial transcription and translation. Recent work from our group has shown that (p)ppGpp plays a critical role in virulence and survival in Vibrio cholerae. The genes, relA and relV, are involved in the production of (p)ppGpp, while the spoT gene encodes an enzyme that hydrolyzes it in V. cholerae. A mutant strain defective in (p)ppGpp production (i.e. ${\Delta}relA{\Delta}relV{\Delta}spoT$ mutant) lost the ability to produce cholera toxin (CT) and lost their viability due to uncontrolled production of organic acids, when grown with extra glucose. In contrast, the ${\Delta}relA{\Delta}spoT$ mutant, a (p)ppGpp overproducer strain, produced enhanced level of CT and exhibited better growth in glucose supplemented media via glucose metabolic switch from organic fermentation to acetoin, a neutral fermentation end product, fermentation. These findings indicates that (p)ppGpp, in addition to its well-known role as a SR mediator, positively regulates CT production and maintenance of growth fitness in V. cholerae. This implicates SR as a promising drug target, inhibition of which may possibly downregulate V. cholerae virulence and survival fitness. Therefore, we screened a chemical library and identified a compound that induces medium acidification (termed iMAC) and thereby loss of wild type V. cholerae viability under glucose-rich conditions. Further, we present a potential mechanism by which the compound inhibits (p)ppGpp accumulation. Together, these results indicate that iMAC treatment causes V. cholerae cells to produce significantly less (p)ppGpp, an important regulator of the bacterial virulence and survival response, and further suggesting that it has a therapeutic potential to be developed as a novel antibacterial agent against cholera.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 1996년도 정기총회 및 학술발표회
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• pp.18-18
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• 1996

Bacteriophage T4 endonuclease V initiates the repair of ultraviolet (UV)-induced pyrimidine dimer photoproducts in duplex DNA. The mechanism of DNA strand cleavage involves four sequential steps: linear diffusion along dsDNA, pyrimidine dimer-specific binding, pyrimidine dimer-DNA glycosylase activity, and AP lyase activity. (omitted)

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 춘계학술대회 논문집
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• pp.54-57
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• 1995

This study is to investigate the switching charac-teritics in the5V-programmable scaled MONOS nonvolatile memory devices, Modified Folwer-Nordheim tunneling mechanism become important when the electric field in the tunneling oxide is 6 MV/cm for E$\_$OT/ <6MV/cm the trap-assisted tunneling mechanism is dominant, The density of nitride bulk trap is found to be N$\_$T/=7.7${\times}$10$\^$18/ cm$\^$-3/ and the energy level of trap is determined to be ø$\_$T/=0.65 eV.

• 한국진공학회지
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• 제1권2호
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• pp.254-258
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• 1992

Iodine 화학수송법으로 성장한 Ni-doped CdGa2Se4와 undoped CdGa2Se4 단결정 의 PL 및 PLE 스펙트럼을 조사하였다. Undoped CdGa2Se4 단결정의 PL 스펙트럼에서는 전도대아래 준 연속적으로 분포된 electron trap과 deep level, 그리고 가전자대 위 0.07eV, 0.12eV에 있는 acceptor level 사이의 전자전이에 의한 2개의 emission band를 2.13eV와 1.20eV 영역에서 관측하였으며, Ni-doped 단결정에서는 Ni2+ 이온의 여기상태 3T1(3P)와 바 닥상태 3T1(3F) 사이의 전자전이에 의한 emission band를 1.48eV 영역에서 관측하였다. 이 러한 결과로부터 제안된 CdGa2Se4의 energy band model은 본 연구의 PL mechanism을 설명하는데 가능함을 보여주었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.291-294
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• 2000

The crystallization behavior and dc Conductivities of CuO-P$_2$O$_{5}$ -Nb$_2$O$_{5}$ -V$_2$O$_{5}$ glasses prepared by quenching on the copper plate were investigated. The conductivities of the glasses were range from 10$^{-5}$ s.$cm^{-1}$ / at room temperature, but the conductivities of the glass-ceramics were 10$^{-3}$ s.$cm^{-1}$ / increased by 10$^2$order. The crystalline product in the glass-ceramics was CuV$_2$O$_{6}$ . The linear relationship between in($\sigma$T) and T$^{-1}$ suggested that the electrical conduction in the present glass-ceramics would be due to a small polaron hopping mechanism.