• 제목/요약/키워드: $pK_a$

검색결과 82,261건 처리시간 0.086초

황의 친핵성 치환반응 (제13보). 메탄올-아세토니트닐계에서의 파라치환 염화벤젠술포닐의 가용매 분해반응 (Nucleophilic Displacement at Sulfur Center (ⅩⅢ). Solvolysis of para-Substituted Benzenesulfonyl Chlorides in MeOH-MeCN Mixtures)

  • 이익춘;구인선
    • 대한화학회지
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    • 제25권1호
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    • pp.7-12
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    • 1981
  • $p-CH_3, p-H, p-Cl 및 p-NO_2 기로 치환된 염화벤젠술포닐의 가용매분해반응을 MeOH-MeCN혼합용매계에서 연구하였다. 반응속도는 p-NO_2 > p-CH_3 > p-H > p-Cl의 순위로서 비직선 Hammett관계를 나타내어 S_N1-S_N2경계반응메카니즘으로 반응함을 알았다. 반응성은 모든 경우 약 90∼95% 메탄올용액에서 최대였으나, fi = \frac{k1}{ki}로 정의되는 각 기질의 메탄올 단위체 선택성(monomer selectivity)은 80% 메탄올 용액에서 최대이며, 그 크기 순위는 p-NO_2 > p-Cl > p-H > p-CH_3$로서 전이상태 구조가 tight할 수록 fi값이 크며 메탄올 단위체를 예민하게 선별 감지함을 알 수 있었다

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TP53 Polymorphisms in Sporadic North Indian Breast Cancer Patients

  • Sharma, Sarika;Sambyal, Vasudha;Guleria, Kamlesh;Manjari, Mridu;Sudan, Meena;Uppal, Manjit Singh;Singh, Neeti Rajan;Bansal, Darpan;Gupta, Arun
    • Asian Pacific Journal of Cancer Prevention
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    • 제15권16호
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    • pp.6871-6879
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    • 2014
  • Background: The purpose of this study was to evaluate the potential association of five (p.P47S, p.R72P, PIN3 Ins16bp, p.R213R and r.13494g>a) polymorphisms of TP53 with the risk of developing breast cancer in North Indian Punjabi population. Methods: We screened DNA samples of 200 sporadic breast cancer patients (197 females and 3 males) and 200 unrelated healthy, gender and age matched individuals for the polymorphisms. Results: For the p.P47S polymorphism, we observed the PP genotype in 99.5% of the patients and PS genotype in only 1 patient. All the controls had the wild type PP genotype. The frequency of RR, RP and PP genotype of p.R72P was 23.5% vs 33.5%, 51.5% vs 45.5% and 25% vs 21% in patients and controls respectively. Heterozygous (RP) genotype was increased in breast cancer patients as compared to controls (51.5 vs 45.5%) and showed 1.61 fold significantly increased risk for breast cancer (OR=1.61, 95% CI, 1.01-2.58, p=0.04). In breast cancer patients the frequencies of A1A1, A1A2 and A2A2 genotypes of PIN3 Ins16bp polymorphism were 67%, 26% and 7% respectively whereas in controls the genotype frequencies were 68.5%, 27.5% and 4% respectively, with no significant difference. For p.R213R (c.639A>G), all individuals had homozygous wild type genotype. The frequencies of GG, GA and AA genotypes of TP53 r.13494g>a polymorphism were 62 vs 67.5%, 33 vs 28% and 5 vs 4.5% in patients and controls respectively, again without significant difference. We observed that RP-A1A1 genotype combination of p.R72P and PIN3 Ins16bp and RP-GG combination of p.R72P and r.13494g>a polymorphism showed significant risk of breast cancer (OR=1.65, 95%CI: 0.98-2.78, p=0.05; OR=1.72, 95%CI: 1.01-2.92, p=0.04). Conclusion: The results of present study indicated that among the five TP53 polymorphisms investigated, the p.R72P polymorphism, and the RP-A1A1 and RP-GG genotype combination contribute to breast cancer susceptibility in North Indians.

p-ADIC HEIGHTS

  • Shim, Kyung-Ah;Woo, Sung-Sik
    • 대한수학회논문집
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    • 제15권1호
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    • pp.37-44
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    • 2000
  • In this paper, for a given p-adic quasicharacter $c_{v}$ : $k_{v}$longrightarrow $Q_{p}$ satisfying a special condition, we will explicitly construct an admissible pairing corresponding to $c_{v}$. We define a p-adic height on the arbitrary abelian varieties associated to divisors and $c_{v}$ by using admissible pairings at every nonarchimedean places. We also show that our p-adic height satisfies similar properties of Neron-Tate's canonical p-adic height.t.ght.t.t.

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흰쥐 말초 혈액 림프구의 분자량 44 kD 단백의 인산화 (Phosphorylation of 44-kilodalton Proteins in Peripheral T-lymphocyte of Rat)

  • 안영수;주일로;오도연;임승욱;박경선
    • 대한약리학회지
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    • 제27권2호
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    • pp.135-144
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    • 1991
  • 흰쥐 말초혈액에서 얻은 T 림프구를 아드레날린성 ${\beta}-$수용체 효현제 및 concanavalin A(Con-A)로 자극해 다음과 같은 결과를 얻었다. 자극이 없는 상태에서의 주 인산화 단백은 분자량 44kD, 등전점 6.8의 단백이었으며 효현제로 자극시키면 분자량 44kD, 등전점 6.3의 단백이 새로이 인산화되어 나타났다. 이 분자량 44kD, 등전점 6.3의 단백은 forskolin에 의해 역시 인산화되며 A-kinase 억제제인 H-8을 전처치하면 인산화의 억제가 나타났다. 또한 Con-A로 자극시키면 44 kD/pI 6.3 단백의 인산화가 증가되었으며 이 인산화의 증가는 CaM kinase 억제제인 W-7 전처치에 의해 억제되었다. H-7은 분자량 44 kD, 등전점 6.8 단백의 인산화를 감소 시켰다. 이상의 결과로 분자량 44 kD 등전점 6.3의 단백은 A-kinase와 CaM kinase 모두에 의해 인산화 되는 기질단백으로서 tryptic peptide map상에서 44 kD/pI 6.8 단백과 44 kD/pI 6.3 단백은 서로 다른 단백임을 알 수 있었다.

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대장암 세포의 방사선저항성에 대한 p53의존성 PI3K의 역할 (Role of p53-dependent PI3K in Radioresistance of Colon Cancer Cells)

  • 이희관;김종석;권형철
    • 한국식품위생안전성학회지
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    • 제25권3호
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    • pp.258-262
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    • 2010
  • Radiotherapy is one of the major therapies for cancer treatment. p53 acts as a central mediator of the cellular response to stressful stimuli, such as radiation. Recently it has been known that activation of the phosphatidylinositol-3-kinase (PI3K) pathway is associated with radioresistance. In this study, we investigated whether X-irradiation up-regulates PI3K in a p53-dependent manner in human colon cancer cells. In order to study this phenomenon, we have treated p53-wild type and p53-mutant type HCT116 cells with X-ray. Treatment of wild type HCT116 cells with 8 Gy resulted in a marked increase in PI3K (p85), which paralleled an increase in PTEN, a counterpart of PI3K. However, these effects of X-rays in the p53-mutant cells were not observed. These results suggest that the X-irradiation-induced up-regulation of PI3K/PTEN pathway is p53-dependent.

고온, 호알칼리성 Bacillus sp. K-17 Xylanase 유전자의 Escherichia coli 에의 클로닝 및 발현 (Molecular Cloning and Expression of a Xylanase Gene from Thermophilic Alkalophilic Bacillus sp. K-17 in Escherichia coli)

  • Sung, Nack-Kie;Chun, Hyo-Kon;Shim, Ki-Hwan;Kang, In-Soo;Teruhiko Akiba
    • 한국미생물·생명공학회지
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    • 제17권3호
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    • pp.178-182
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    • 1989
  • 고온, 호알칼리성 Bacillus K-17 균주에서 한가지 xylanase 유전자를 pBR322를 벡터로 이용하여 클로닝시켰다. Xylan을 함유하는 LB 한천배지에서 분해환을 형성하는 대장균 형질전환주에서 재조합 플라스미드 pAXl13을 분리하였으며, 본 pAXl13 은 pBR322와 고온, 호알칼리성 Bacillus K-17균주 염색체 DNA의 4.3Kb HindIII 절편으로 구성되어 있었다. Biotin으로 표식된 pAXl13을 probe로 하여 상동성시험을 하여 본 결과, pAXl13에 존재하는 4.3Kb Hind III 절편은 고온, 호알칼리성 Bacillus K-17 균주 유래임을 확인하였다. pAXl13 을 가지는 E. coli 균주가 생성하는 xylanase는 균체외에 존재하였으며 그 효소학적 성질은 고온, 호알칼리성 Bacillus K-17 균주의 xylanase I 과 II중에서 xylanase I과 동일하였다.

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독수리(Aegypius monachus)의 흡입마취에서 Capnography를 이용한 호기말 이산화탄소분압 모니터링 (Capnographic Monitoring of End-Tidal Partial Pressure of Carbon Dioxide in Anesthetized Cinereous vultures (Aegypius monachus))

  • 박원규;석성훈;박세진;이승용;김영기;황재민;정동혁;이희천;연성찬
    • 한국임상수의학회지
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    • 제32권4호
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    • pp.380-384
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    • 2015
  • The relationships between end-tidal partial pressure of carbon dioxide ($P_{ET}CO_2$) and arterial partial pressure of carbon dioxide ($P_aCO_2$), and between $P_{ET}CO_2$ and blood pH in isoflurane-anesthetized cinereous vultures were evaluated. Nine cinereous vultures (weighing 7.3-9.5 kg) were anesthetized via mask with isoflurane, intubated, and connected to a mechanical ventilator. By mechanical ventilator, respiratory rate was altered to achieve a $P_{ET}CO_2$ randomly selected among 30 to 35 mmHg. $P_aCO_2$ and blood pH were determined in serial arterial samples and compared with concurrent $P_{ET}CO_2$ measured with a sidestream capnography. Thirty six samples, nine cinereous vultures were tested 4 times each, were used to determine correlations coefficients between $P_aCO_2$ and $P_{ET}CO_2$, and between $P_{ET}CO_2$ and blood pH. Strong correlations were observed between $P_aCO_2$ and $P_{ET}CO_2$ (r = 0.951, P = 0.000, y = 1.679x - 30.236, $R^2=0.905$) as well as between $P_{ET}CO_2$ and blood pH (r = -0.728, P = 0.000, y = -0.024x + 8.389, $R^2=0.530$) with Pearson's correlation coefficient and simple linear regression. These results suggest that the capnography used provided a sufficiently accurate estimation of $P_aCO_2$ and blood pH. Thus, the monitoring of $P_{ET}CO_2$ can be useful method to prevent hypoventilation for cinereous vultures receiving mechanical ventilation.

The Study of Bfa1pE438K Suggests that Bfa1 Control the MitoticExit Network in Different Mechanisms Depending on DifferentCheckpoint-activating Signals

  • Kim, Junwon;Song, Kiwon
    • Molecules and Cells
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    • 제21권2호
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    • pp.251-260
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    • 2006
  • During mitosis, genomic integrity is maintained by the proper coordination of anaphase entry and mitotic exit via mitotic checkpoints. In budding yeast, mitotic exit is controlled by a regulatory cascade called the mitotic exit network (MEN). The MEN is regulated by a small GTPase, Tem1p, which in turn is controlled by a two-component GAP, Bfa1p-Bub2p. Recent results suggested that phosphorylation of Bfa1p by the polorelated kinase Cdc5p is also required for triggering mitotic exit, since it decreases the GAP activity of Bfa1p-Bub2p. However, the dispensability of GEF Lte1p for mitotic exit has raised questions about regulation of the MEN by the GTPase activity of Tem1p. We isolated a Bfa1p mutant, $Bfa1p^{E438K}$, whose overexpression only partially induced anaphase arrest. The molecular and biochemical functions of $Bfa1p^{E438K}$ are similar to those of wild type Bfa1p, except for decreased GAP activity. Interestingly, in $BFA1^{E438K}$ cells, the MEN could be regulated with nearly wild type kinetics at physiological temperature, as well as in response to various checkpoint-activating signals, but the cells were more sensitive to spindle damage than wild type. These results suggest that the GAP activity of Bfa1p-Bub2p is responsible for the mitotic arrest caused by spindle damage and Bfa1p overproduction. In addition, the viability of cdc5-2 ${\Delta}bfa1 $ cells was not reduced by $BFA1^{E438K}$, suggesting that Cdc5p also regulates Bfa1p to activate mitotic exit by other mechanism(s), besides phosphorylation.

SCK 선암세포주에서 방사선 조사에 의해 유도되는 Apoptosis에 미치는 암유전자의 발현 (The Expression of Oncogenes on the Radiation-induced Apoptosis in SCK Mammary Adenocarcinoma Cell Line)

  • 이헝식;박홍규;문창우;윤선민;허원주;정수진;정민호;이상화
    • Radiation Oncology Journal
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    • 제17권1호
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    • pp.70-77
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    • 1999
  • 목적 : 연구자들은 배양 배지의 산성환경이 SCK 선암세포에서 apoptosis를 유도하는 것과 산성환경이 SCK 선암 세포주에서 방사선에 의해 유도되는 apoptosis를 억제시킨다고 관찰하고 apoptosis 관련 유전자들인 p53, p21/WAF/CIP, Bcl-2 및 Bax 들의 발현과 배양 배지 pH 환경과의 연관성을 관찰하였다. 대상 및 방법 : SCK 선암 세포주를 체외 방사선 조사기를 이용하여 방사선 120Gy 조사 후 규정된 시간에 DNA fragmentation을 전기 영동으로 관찰하였다. 실험 조작으로 apoptosis가 유발된 세포군을 정량적으로 분석하고 세포주기 분석을 위하여 FACScan을 이용하였다. Apoptosis 관련 유전자들인 p53, P21/WAF/CIP, Bcl-2 및 Bax 들의 발현은 western blot으로 관찰하였다. 결과 : SCK 선암 세포주에서 방사선에 의해 유도되는 apoptosis는 산성환경(pH 6.6)에서는 apoptosis의 유발이 억제 된다는 사실을 관찰할 수 있었다. 세포주기 분석에서는 방사선조사 후 apoptosis가 뚜렷히 관찰된 pH 7.5 배양 배지 조건에 비하여 pH 6.6 배양 배지 조건에서 현저한 G2/M arrest가 관찰 되었다. apoptosis 관련 유전단백 분석에서는 Bcl-2 유전단백은 두 군 공히 발현의 차이를 관찰할 수 없었고, p53 및 p21은 pH 7.5 배양 배지 환경에서 뚜렷한 발현의 증가를 관찰하였고, p21은 pH 6.6 배양 배지 환경에서는 발현을 관찰할 수 없었다. Bax는 pH 7.5 배양 배지 환경에서 pH 6.6 환경에 비해 경미한 발현의 증가 및 지속성을 관찰하였다. 결론 . 저자들은 SCK 선암 세포주를 대상으로 방사선조사 후 상이한 pH 7.5 와 6.6의 배양 배지 조건에 따른 apoptosis의 관찰에 영향을 주는 유전자 발현에 관한 연구에서 Bcl-2 family의 발현에 비해 세포주기 관련 유전단백들인 p53 발현과 이에 따른 p21의 발현차이가 확연한 p53-dependent apoptotic pathway를 확인하였다. 방사선 조사 후 pH 6.6의 배양 배지 조건에서의 apoptosis 현상을 관찰할 수 없었던 이유는 pH 6.6의 경우 50-60$\%$의 세포가 G2/M arrest에서 세포주기를 순환하지 못함을 확인하였기에 G2/M arrest의 해지와 더불어 순환되는 세포주기의 결과에 따른 post-mitotic apoptosis 현상의 장애로 추론하였다.

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뉴트럴레드가 고정화된 다공성 졸-겔 필름을 이용한 고감도 광섬유 pH 센서의 특성 (High-Sensitive Fiber-Optic pH Sensor Using Neutral Red Immobilized in Porous Sol-Gel Film)

  • 전다영;유욱재;신상훈;한기택;박장연;박병기;조승현;이봉수
    • 센서학회지
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    • 제21권3호
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    • pp.223-228
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    • 2012
  • In this study, a fiber-optic pH sensor based on a pH sol-gel film is fabricated. The sol-gel film is made by co-polymerizing tetramethoxysilane, trimethoxymethylsilane, ethanol and distilled water. As a pH indicator, a neutral red is immobilized in a thin porous film formed by the sol-gel process. The pH change in a sensing probe gives rise to a change in the color of the pH sol-gel film, and the absorbance of reflected light through the pH sol-gel film is also changed. By using a spectrometer, therefore, the spectra of reflected lights in the sensing probe with different pH values are measured. Also, the relationships between the pH values and the absorbance are analyzed on the basis of the color variations of the pH sol-gel films. In repeated experiments, the fiber-optic pH sensor shows that it has reversibility, a high reproducibility and a wide absorbance change in a pH range from pH 5 to 9. Also, we confirmed that the fabricated pH sol-gel film exhibits a fast response time, little or no pH indicator leaching and a dynamic range of 2.04 dB from pH 5 to 9. Based on the results of this study, a fiber-optic pH sensor can be developed for the pH monitoring in the harsh environments.