• 제목/요약/키워드: K_{cat}/K_m$

검색결과 394건 처리시간 0.042초

EFFECT OF CIS-ELEMENT ON THE REGULATION Of TROUT LIVER CYTOCHROME P450IAl GENE EXPRESSION

  • Hwang, Jung E.;Sheen, Yhun Y.
    • 한국응용약물학회:학술대회논문집
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    • 한국응용약물학회 1996년도 춘계학술대회
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    • pp.188-188
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    • 1996
  • In order to gain insight into the mechanism of the regulation of cytochrome P450IAl by arylhydrocarbon, the 5'-flanking region of a trout CYP450IAl 5'flanking DNA was cloned into pCAT-basic vector and it was transfected into Hepa-1 cells. 3MC treatment to hepa Ⅰ cells transfected with fish CYP450IAl-CAT construct results in mRNA increased by 2.81 fold when it was compared with that of control This increase of mRNA was decreased by concomitantly treated flavonoids such as morin. The levels of CAT mRNA that was treated with morin was 29.2-58.0% of 3MC stimulated CAT mRNA. Further investigation to find out if there are DRE, XRE or negative regulatory cis element in CYP450IA1 gene was undertaken. Results of the deletion study of 5'flanking DNA of trout P450IA indicate the existance of the negative(-1600 ~ -1300). CAT mRNA was about two-fold higher in deleted trout CYP450IAl-CAT construct transfected cells compared to the wi Id type trout CYP450IAl-CAT construct transfected cells. And The stimulatory effect of 3MC was no longer observed in col Is containing deleted CAT construct. [Supported by grants from the Korean Ministry of Education]

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STUDY CYTOCHROME P450IA1 GENE EXPRESSION BY RTPCR.

  • Lee, Soo-Young;Yhun Y. Sheen
    • 한국응용약물학회:학술대회논문집
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    • 한국응용약물학회 1995년도 춘계학술대회
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    • pp.128-128
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    • 1995
  • To investigate the mechanism of the regulation of cytochrome P450IA1 gene expression, ethoxyresorufin deethylase(EROD) and benzo(a)pyrene hydroxylase in B6 mouse liver, in isolated perfused rat liver system. and in B6 mouse hepatocyte Hepa-I cells were examined. In C57BL/6N mouse, 3-methylcholan- throne( 3MC ) treatment have resulted in the stimulation of EROD activity based on fluorometry by 2.79 fold comparirng with that of control. Measurement of mRNA of cytochrome P450 was carried out by either nothern blot or dot blot analysis. Findings are similar to that of studies with enzymes. Furhtermore, when RTPCR method was applied to detect mRNA in Hepa I cell and liver tissues the results were more clear. Cytochrome P450IA1 upstream DNA containing CAT construct was transfected into Hepa-1 cells. After transfection of CAT construct, 3MC and flavonoids, such as, chrysin, hesperetin, kaempferol, morin, myricetin and aminoyrine were treated. 48 Hours after treatments, cells were harvested and assayed for CAT mRNA by RTPCR. 3MC treatment to hepa I cells transfected with trout P450IA1-CAT construct increased CAT mRNA by 2.81 fold when it was compared with that of control. This increase CAT mRNA was decreased by concomitantly treated flavonoids and aminopyrine. The level of CAT protein was 29.2-58.0% of 3MC stimulated CAT protein. Results of this study suggested that RTPCR seems to be a very good method to study regulation of gene expression in liver tissue or Hepa cells.

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Inhibitory effect of Ulmus davidiana Planch extracts on bone resorption mediated by processing of cathepsin K in cultured mouse osteoclasts

  • Park, Jun-Sung;Kim, Kyung-Ho;Jo, Hyun-Seog;Kim, Kap-Sung;Hwang, Min-Seob
    • Journal of Acupuncture Research
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    • 제22권2호
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    • pp.55-70
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    • 2005
  • Objective: Ulmus davidiana Planch (Ulmaceae) has long been known to have anti-inflammnatory in the traditional Korean medicine. UD has been reported as a good enhancer for bone healing. Methods : In this experiment, we investigate the Inhibitory effects of UD on bone resorption using the bone cells culture. Different concentrations of crude extract of UD were added to mouse bone cells culture. The mitochondria activity of the bone cells after exposure was determined by colorimetric MIT assay. It was demonstrated that UD has potential effects on bone cells culture without any cytotoxicity. The most effective concentration of UD on bone cells were $100\;{\mu}g/ml$. Cathepsin K (Cat K) is the major cysteine protease expressed in osteoclasts and is thought to play a key role in matrix degradation during bone resorption. Results : When mouse long bone cells including osteoclasts and osteoblast were treated with the PI3-Kinase inhibitor, wortmannin (WT), WT prevented the osteoclast-mediated intracellular processing of Cat K. Similarly, treatment of osteoclasts-containing long bone cells with UD extracts prevented the intracellular maturation of Cat K, suggesting that UD may disrupt the intracellular trafficking of pro Cat K. This is similar to that of WT. Since secreted proenzymes have the potential to reenter the cell via mannose-6-phosphate (M6P) receptor, to prevent this possibility, we tested WT and UD in the absence or presence of M6P. Inhibition of Cat K processing by WT or UD was observed in a dose-dependent manner. Furthermore, the addition of M6P resulted in enhanced potency of WT and UD. Conclusion : UD dose-dependently inhibited in vitro bone resorption with a potency similar to that observed for inhibition of Cat K processing.

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SecM에서 유래한 접착펩타이드에 의한 라이보솜 정지를 우회하는 SSU rRNA 돌연변이체 발굴을 위한 유전학적 시스템 개발 (Development of Genetic System for Isolation of SSU rRNA Mutants that Bypass SecM-Mediated Ribosome Stalling)

  • 하혜정;김홍만;염지현;이강석
    • 미생물학회지
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    • 제44권4호
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    • pp.271-276
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    • 2008
  • 최근 단백질 합성 과정 중 라이보솜의 일시적인 정지에 의한 라이보솜의 A자리에서 전사체가 분해되는 현상이 여러 생명체에서 보고되었다. 이러한 현상이 라이보솜의 작은 소단위체를 이루고 있는 SSU rRNA의 기능과 관련 있는지를 알아보기 위해, SecM에서 유래한 접착펩타이드에 의한 라이보솜 정지를 우회하는 SSU rRNA 돌연변이체 발굴을 위한 유전학적 시스템을 개발하였다. 이 시스템에서는 SecM에서 유래한 접착펩타이를 포함하는 CAT 단백질을 코딩하는 CAT-SecM 전사체가 플라스미드에서 유래한 SSU rRNA를 포함한 재조합 라이보솜에 의해서만 해독된다. 이러한 재조합 라이보솜은 접착펩타이드를 합성한 후 CAT-SecM mRNA 상에서 일시 정체하며, 재조합 라이보솜의 발현은 이 전사체의 양을 감소시키는 것을 확인하였다. 이러한 결과는 개발된 시스템을 이용해 라이보솜 검지를 우회하는 SSU rRNA 돌연변이체의 선별이 가능하다는 것을 보여주며, 이러한 변이체에 대한 연구는 단백질 합성 단계에서 일어나는 라이보솜 정지와 전사체 절단 현상에 있어서, SSU rRNA의 역할을 규명하는데 기여할 것이다.

제주마(濟州馬)의 catalase형(型)에 관(關)한 연구(硏究) (Studies on catalase type in Cheju native horse)

  • 현해성;김자권;장덕지
    • 대한수의학회지
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    • 제31권2호
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    • pp.167-170
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    • 1991
  • The catalase phenotypes and the gene frequencies in erythrocyte of 223 Cheju native horses were studied by starch gel electrophoresis. The results obtained were as follows: 1. In the catalase phenotypes, three phenotypes, CatF, CatM and CatS, which were controlled by two allelic genes, $Cat^F$ and $Cat^S$, were observed and their frequencies of appearance were 24.21%, 47.53%, and 28.25% respectively. 2. The distribution of gene frequency was calculated as 0.480 in $Cat^F$ and 0.520 in $Cat^S$.

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The Effect of pH and Various Cations on the GTP Hydrolysis of Rice Heterotrimeric G-protein α Subunit Expressed in Escherichia Coli

  • Seo, Hak-Soo;Jeong, Jin-Yong;Nahm, Min-Yeop;Kim, Sam-Woong;Lee, Sang-Yeol;Bahk, Jeong-Dong
    • BMB Reports
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    • 제36권2호
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    • pp.196-200
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    • 2003
  • Previously, we reported the biochemical properties of RGA1 that is expressed in Escherichia coli (Seo et al., 1997). The activities of RGA1 that hydrolyzes and binds guanine nucleotide were dependent on the $MgCl_2$ concentration. The steady state rate constant ($k_{cat}$) for GTP hydrolysis of RGA1 at 2 mM $MgCl_2$ was $0.0075{\pm}0.0001\;min^{-1}$. Here, we examined the effects of pH and cations on the GTPase activity. The optimum pH at 2 mM $MgCl_2$ was approximately 6.0; whereas, the pH at 2 mM $NH_4Cl$ was approximately 4.0. The result from the cation dependence on the GTPase (guanosine 5'-triphosphatase) activity of RGA1 under the same condition showed that the GTP hydrolysis rate ($k_{cat}=0.0353\;min^{-1}$) under the condition of 2mM $NH_4Cl$ at pH 4.0 was the highest. It corresponded to about 3.24-fold of the $k_{cat}$ value of $0.0109\;min^{-1}$ in the presence of 2 mM $MgCl_2$ at pH 6.0.

ROLE OF 5'FLANKING DNA FOR THE REGULATION OF CYP450IA1 GENE EXPRESSION

  • Sheen, Yhun-Y.
    • 한국응용약물학회:학술대회논문집
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    • 한국응용약물학회 1995년도 제3회 추계심포지움
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    • pp.153-155
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    • 1995
  • To investigate the mechanism of the regulation of cytochrome P450IAl, the 5'-flanking region of a trout cytochrome P4501Al was cloned into the CAT basic expression vector at HindⅢ site. This trout Cytochrome P450IAl upstream DNA containing CAT construct was transfected into Hepa-1 cells .3MC treatment to hepa I cells transfected with trout P450IAl-CAT construct increased CAT protein and mRNA by 2.81 fold when it was compared with that of control. This increase CAT protein and mRNA was decreased by concomitantly treated flavonoids and aminopyrine. The level of CAT protein was 29.2-58.0% of 3MC stimulated CAT protein.

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Catalase 첨가에 따른 돼지 정액 동결 및 융해 후 생존 정자에서 Hydrogen Peroxide의 감소 (The Reduction of Hydrogen Peroxide in Viable Boar Sperm Cryopreserved in the Presence of Catalase)

  • 김수희;이영준;강태운;김용준
    • 한국임상수의학회지
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    • 제28권1호
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    • pp.13-19
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    • 2011
  • 요 약: 정액 동결 과정은 활성산소종의 생성을 유발하며, 생성된 활성산소종은 정자의 손상을 일으키는 것으로 알려져 있다. 따라서 본 연구의 목적은 동결 과정 중 항산화 효소 중 하나인 catalase (CAT)를 첨가함으로써 융해 후 정자의 기능과 활성산소종의 수준에 미치는 효과를 알아보고자 하였다. 5마리 돼지에서 채취한 정액은 0 (대조군), 200, 400 U/mL CAT가 첨가되어 있는 동결 희석액으로 각각 동결하였다. 융해 후, 정자 운동성, 생존성, 정상 형태율, 형질막 온전성, 미토콘드리아 기능, 세포내 ROS를 평가하였다. CAT는 400 U/mL의 농도에서 전체 정자 운동성을 향상시켰지만 (P < 0.05), 전진 운동성, 생존성, 기형율, 형질막 온전성, 미토콘드리아 기능의 향상을 나타내지 않았다. 활성산소종의 평가에서, CAT는 융해된 생존 정자의 ${\cdot}O_2$의 감소에는 효과를 나타내지 않은 반면 $H_2O_2$를 감소시켰다(P < 0.05). 결론으로 CAT는 동결 및 융해된 정자의 질을 향상시키는 데 큰 효과를 나타내진 않았지만 생존 정자에서 $H_2O_2$을 제거함로써 생존정자의 산화적 손상을 감소시킬 수 있으리라 판단된다.

L-carnitine Supplemented Extender Improves Cryopreserved-thawed Cat Epididymal Sperm Motility

  • Manee-In, S.;Parmornsupornvichit, S.;Kraiprayoon, S.;Tharasanit, T.;Chanapiwat, P.;Kaeoket, K.
    • Asian-Australasian Journal of Animal Sciences
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    • 제27권6호
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    • pp.791-796
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    • 2014
  • Cryopreservation of epididymal sperm is an effective technique to preserve genetic materials of domestic cats and wild felids when they unexpectedly die. However, this technique inevitably causes detrimental changes of cryopreserved-thawed spermatozoa, for example, by physical damage and excessive oxidative stress. L-carnitine is an antioxidant that has been used to improve sperm motility in humans and domestic animals. This study aimed to investigate the effects of L-carnitine on cat epididymal sperm quality following cryopreservation and thawing. After routine castration, cauda epididymides were collected from 60 cat testes. The epididymal spermatozoa from 3 cauda epididymides were pooled as 1 replicate. Spermatozoa samples (16 replicates) were examined for spermatozoa quality and then randomly divided into 4 groups: 0 mM L-carnitine (control), 12.5 mM, 25 mM and 50 mM L-carnitine. The sperm aliquots were then equilibrated and conventionally frozen. After thawing, sperm motility, plasma membrane integrity, DNA integrity and acrosome integrity were evaluated. The 25 mM L-carnitine significantly improved sperm motility compared with a control group (p<0.05), although this was not significantly different among other concentrations. In conclusion, supplementation of 25 mM L-carnitine in freezing extender improves cauda epididymal spermatozoa motility. The effects of L-carnitine on the levels of oxidative stress during freezing and thawing remains to be examined.

In Vivo Quantitative Analysis of PKA Subunit Interaction and cAMP Level by Dual Color Fluorescence Cross Correlation Spectroscopy

  • Park, Hyungju;Pack, Changi;Kinjo, Masataka;Kaang, Bong-Kiun
    • Molecules and Cells
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    • 제26권1호
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    • pp.87-92
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    • 2008
  • We employed dual color Fluorescence Cross Correlation Spectroscopy (FCCS) to measure the interaction between PKA regulatory (RII) and catalytic subunits (CAT) in living cells. Elevation of intracellular cAMP with forskolin decreased the cross-correlation amplitude between RFP-fused RII (RII -mRFP) and GFP-fused CAT (CAT-EGFP) by 50%, indicating that cAMP elevation leads to dissociation of RII-CAT complexes. Moreover, diffusion coefficient analysis showed that the diffusion rate of CAT-EGFP was significantly increased, suggesting that the decreased RII-CAT association caused by cAMP generated free CAT subunits. Our study demonstrates that in vivo FCCS measurements and their quantitative analysis permit one not only to directly quantify protein-protein interactions but also to estimate changes in the intracellular cAMP concentration.