• Molecules and Cells
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• 제38권5호
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• pp.409-415
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• 2015

Low-barrier hydrogen bonds (LBHBs) have been proposed to have important influences on the enormous reaction rate increases achieved by many enzymes. ${\Delta}^5$-3-ketosteroi isomerase (KSI) catalyzes the allylic isomerization of ${\Delta}^5$-3-ketosteroid to its conjugated ${\Delta}^4$-isomers at a rate that approache the diffusion limit. Tyr14, a catalytic residue of KSI, has been hypothesized to form an LBHB with the oxyanion of a dienolate steroid intermediate generated during the catalysis. The unusual chemical shift of a proton at 16.8 ppm in the nuclear magnetic resonance spectrum has been attributed to an LBHB between Tyr14 $O{\eta}$ and C3-O of equilenin an intermediate analogue, in the active site of D38N KSI. This shift in the spectrum was not observed in Y30F/Y55F/D38N and Y30F/Y55F/Y115F/D38N mutant KSIs when each mutant was complexed with equilenin, suggesting that Tyr14 could not form LBHB with the intermediate analogue in these mutant KSIs. The crystal structure of Y30F/Y55F/Y115F/D38N-equilenin complex revealed that the distance between Tyr14 $O{\eta}$ and C3-O of the bound steroi was within a direct hydrogen bond. The conversion of LBHB to an ordinary hydrogen bond in the mutant KSI reduced the binding affinity for the steroid inhibitors by a factor of 8.1-11. In addition, the absence of LBHB reduced the catalytic activity by only a factor of 1.7-2. These results suggest that the amount of stabilization energy of the reaction intermediate provided by LBHB is small compared with that provided by an ordinary hydrogen bond in KSI.

• Applied Biological Chemistry
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• 제49권4호
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• pp.315-321
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• 2006

유기인계나 카바메이트 살충제는 신경전달계 효소인 Acetylcholinesterase(AchE)를 저해하므로 농산물중에서 농약의 잔류여부 확인이 가능하다. 이러한 바이오센서는 환경 관리를 위한 민감한 센서로 사용될 수 있으며, 최근에는 AchE를 이용한 잔류농약을 측정할 수 있는 바이오센서 기술이 주목을 받고 있다. 우리는 최근에 감광성고분자물질인 고정화물질을 이용하여 광기교화반응에 의해 AchE를 막에 고정화시켜 잔류농약을 측정할 수 있는 바이오센서를 개발하였다. 고정화시킨 효소는 $4^{\circ}C$에서 6개월 동안 안정하였으며, 유기인계와 카바메이트계의 농약에 대한 반응에서도 기존의 용액형태의 효소보다 민감한 반응을 보였다. 또한 본 연구개발로 제작된 바이오센서에 의한 잔류농약 측정법은 용액형태의 효소에 의한 잔류농약 측정법보다 신속 간편하여 5분 안에 잔류농약에 대한 효소의 억제율을 측정할 수 있었으며, chlorpyrifos, cabaryl, carbofuran methidathion에 대해 농약의 검출 능력이 정밀분석법에 의한 검출한계에 근접한 것으로 나타났다

• Journal of Preventive Medicine and Public Health
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• 제40권6호
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• pp.487-494
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• 2007

Objectives : Little is known about the physician-related factors that are associated with the management of Hypertension. The purpose of this study was to determine the physician-related factors associated with blood pressure control in hypertensive patients. Methods : We surveyed 154 physicians at 117 public health (subhealth) centers in Gyeonggi-do, Forty-one physicians completed the survey (response rates : 26.6%) and 31 physicians were finally included as the study subjects. Using the information obtained from the self-reported survey, we measured the physician-related factors associated with hypertension control, including their perception of hypertension, prescription patterns (combination prescription rates, specific antihypertensives prescription rates among patients with diabetes mellitus), and sociodemographic factors. We then collected data on blood pressure and medication use in patients seen by these physicians from the health center#s information system. We compared the physicians# perceived hypertension control rates with the actual rates, and then evaluated the rate of high overestimation (overestimation by more than 25% of the median degree of hypertension control rate overestimation) among the physicians. The physicians# antihypertensive prescription patterns were also evaluated. Multiple logistic regression analysis was used to evaluate the independent association between hypertension control and physician-related factors. Results : The physicians tended to overestimate the proportion of their patients with controlled blood pressure (79.5% perceived vs. 57.8% actual). The percentage of physicians with high overestimation was 35.5% (11 physicians). The physicians with lower control rates were more likely to highly overestimate their patients# control rates. Physicians with below-median actual control rates tended to prescribe fewer combination treatments for patients with uncontrolled blood pressure and angiotensin-converting enzyme inhibitors or fewer angiotensin receptor blockers for patients with diabetes mellitus. The rate of high overestimation by physicians was 1.31 times higher in patients with uncontrolled blood pressure than in patients with other conditions (OR=1.31, 95% CI : 1.17-1.48). Conclusions : Physicians have a tendency to overestimate the rates of hypertension control in their patients. Because physicians have a direct role in treatment outcomes, physicians# overestimation about hypertension management contributes to inadequate blood pressure control. Thus, interventions for improving physician# awareness regarding the management of patients with hypertension are needed.

• Applied Biological Chemistry
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• 제45권2호
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• pp.53-58
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• 2002

Quinacrine은 수소이온 농도변화에 민감한 형광 probe로서 양성자와 결합하지 않은 형광형이나, 양성자와 결합한 비형광형으로 존재한다. 따라서, quinacrine은 $H^+-ATPase$에 의한 수소이온이동 활성 측정에 이용된다. 본 연구에서는 토마조 뿌리조직에서 분리한 마이크로솜에서 quinacrine의 형광성을 이용한 $H^+-ATPase$ 활성측정의 최적 조건을 조사하였다. Quinacrine의 형광변화는 반응용액 중의 단백질 함량이 $0.43{\mu}g/{\mu}l$에서25-26% 감소하여 10%의 quinacrine 형광을 감소시키는 데 약 100nmo1/min의 $H^+-ATPase$ 활성이 필요함을 알 수 있었다. Quinacrine의 최대 형광변화는 pH 7.0-7.2 범위와 $2mM\;Mg^{2+}$ 조건에서 일어났다. 이것은 기존에 보고한 $H^+-ATPase$의 특성과 일치하여, quinacrine의 형광변화가 $H^+-ATPase$의 활성을 잘 반영하고 있음을 보인다. 원형질막 및 액포막 $H^+-ATPase$들의 선택적 저해제인 vanadate와 $NO_3-$는 각각의 효소에 의한 수소이온이동 활성을 저해하는데 성공적임을 확인하였다. 이상의 결과로 quinacrine이 토마토 뿌리조직에서 분리한 마이크로솜의 수소이온이동 활성측정에 유용하게 이용될 수 있음을 확인하였다.

• 고려인삼학회:학술대회논문집
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• 고려인삼학회 1984년도 학술대회지
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• pp.257-275
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• 1984

Enzymatic browning is considered desirable in tea and tobacco processing but undesirable in many fruits processing at the present time. It is necessary to understand the nature of the enzyme, phenoloxidase, in order to control browning reactions, and extend its effects to formation of browning products as antioxidants in ginseng. Ginseng exhibits antioxidant activity when incorporated with turkey dark meat patties. The activity in red ginseng showed about two times stronger than white ginseng. One of the phenolic antioxidants from fresh, white and reprocessed white ginseng was identified as phenol 2.6 Bis(1.1 dimethyl ethyl) 4-methyl among several unknown compounds by GC/mass spectrometer. In red ginseng, no phenol 2.6 Bis (1.1 dimethyl ethyl) 4-methyl was detected, the compound may be polymerized by phenoloxidase and form some higher molecular compounds which may possess high antioxidant activity. Phenoloxidase isozymes in fresh Korean ginseng (panax ginseng C.A. Meyer) were extracted with phosphate buffer at pH 7.3. The isozymes were purified through ammonium sulfate fractionation, dialysis and chromatography on a DEAE-cellulose column. Two groups of phenoloxidase were shown to be present, one in the floating agglomerated group and the other in the precipitate. group from the 0.85 saturation ammonium sulfate. The DEAE-cellulose column chromatography, the phenoloxidase isozyme present in the precipitate appears as the first peak (I), and that in the agglomerate in the second peak (II). Isozyme I showed higher activity with catechin and catechal, and isozyme II showed higher activity with p-cresol. The isozyme showed two optimum pH activity one at pH 4.5 and the other at 8.5 with catechin as substrate. Korean ginseng phenoloxidase has high heat stability. When heated at $75^{\circ}C$ for 2 hours, its activity remained $90\%\;and\;80\%$ on phenoloxidase I and II respectively. Phenoloxidase I was most active on (+) catechin followed by p-cresal, catechol and epicatechin. Phenoloxidase II was most active on p-cresal followed by (+) catechin, catechol, p-coumanic acid and epicatechin. Sodium bisulfite, sodium cyanide, ascorbic acid glutachion in the oxidized form, sodium diethyl dithiocarbomate and ethylendiamine tetra acetate (EDTA) acted as inhibitors. Red ginseng color development was initiated by phenoloxidase and finished by a followed sun drying process. The antiaging activity of ginseng may be initiated by the antioxidant in the ginseng.

• 한국자원식물학회지
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• 제25권2호
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• pp.285-292
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• 2012

본 연구는 사과의 자가불화합성 현상에 효과적인 저해제와 활력제를 탐색하기 위해 여러 종류의 물질을 조사하였다. 후지 사과의 화주조직에서 분비되는 S RNase에 대한 저해효과를 조사하기 위해 $In$ $vitro$ 상에서 효소 저해제를 넣어 효소활성을 측정한 결과, Iron(II) Sulfate에서 현저하게 활성이 24.3% 감소되어 저해효과가 뛰어난 것으로 나타났다. $In$ $vitro$ 상에서 후지 사과의 화분관 신장 억제 효과를 분석한 결과, 후지 사과의 화분은 2% Sucrose 신장배지 보다 10% Sucrose 신장배지에서 약 90% 이상의 높은 발아율을 나타났다. 또한 저해제와 첨가제 처리에 의한 안동지역과 영주지역의 Field에서 후지 사과 착과율 조사 결과, 안동지역에서는 $A^+$+V6 2회 처리가 86.1%로 중심화착과율이 가장 높았으며, 영주지역에서는 $A^+$+V1 1회 처리가 91.9%로 중심화 착과율이 가장 높은 것으로 나타났다.

• 대한수의학회지
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• 제38권1호
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• pp.29-42
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• 1998

$Mg^{2+}$ is one of the most abundant divalent cations in mammalian body(0.2~1.0mM) and the important physiological roles are : first, the cofactor of many enzyme activities, second, the regulator of glycolysis and DNA synthesis, third, the important role of bioenergetics by regulating of phosphorylation, fourth, the influence of cardiac metabolism and function. In this work we have investigated the regulation of the $Mg^{2+}$ induced by ${\alpha}_1-adrenoceptor$ stimulation in perfused guinea pig hearts and isolated myocytes. The $Mg^{2+}$ content of the perfusate or the supernatant was measured by atomic absorbance spectrophotometry. The elimination of $Mg^{2+}$ in the medium increased the force of contraction of right ventricular papillary muscles, and the left ventricular pressure. Phenylephrine also enhanced the force of contraction in the presence of $Mg^{2+}-free$ medium. ${\alpha}_1-Agonists$ such as phenylephrine and methoxamine were found to induce $Mg^{2+}$ efflux in both perfused hearts and myocytes. These effects were blocked by prazosin, an ${\alpha}_1-adrenoceptor$ antagonist. The $Mg^{2+}$ influx could also be induced by phenylephrine and R59022, a diacylglycerol kinase inhibitor. In the presence of protein kinase C(PKC) inhibitors, phenylephrine produced an increase in $Mg^{2+}$ efflux from perfused hearts. Furthermore, $Mg^{2+}$ efflux by phenylephrine was amplified by phorbol 12-myristate 13-acetate(PMA). This enhancement of $Mg^{2+}$ efflux by PMA was blocked by prazosin in perfused hearts. By contrast, the $Mg^{2+}$ influx could be induced by verapamil, nifedipine, ryanodine in perfused hearts, but not in myocytes. $W^7$, a $Ca^{2+}$/calmodulin antagonist, completely blocked the phenylephrine-induced $Mg^{2+}$ efflux in perfused hearts. In conclusion, $Mg^{2+}$ is responsible for the cardiac activity associated with ${\alpha}_1-adrenoceptor$ stimulation. The mobilization of $Mg^{2+}$ is decreased or increased by ${\alpha}_1-adrenoceptor$ stimulation in guinea pig hearts. These responses may be related specifically to the respective pathways of signal transduction. A decrease in $Mg^{2+}$ efflux by ${\alpha}_1-adrenoceptor$ stimulation in hearts can be through PKC dependent and intracellular $Ca^{2+}$ levels.

• Archives of Pharmacal Research
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• 제21권5호
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• pp.581-590
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• 1998

We developed a novel water-soluble camptothecin analobue, CKD602, and evaluated the inhibition of topoisomerase I and the antitumor activities against mammalian tumor cells and human tumor xenografts. CKD602 was a nanomolar inhibitor of the topoisomerase I enzyme in the cleavable complex assay. CKD602 was found to be 3 times and slightly more potent than topotecan and camptothecin as inhibitors of topoisomerase, respecitively. In tumor cell cytotoxicity, CKD602 was more potent than topotecan in 14 out of 26 human cancer cell lines tested, while it was comparable to camptothecin. CKD602 was tested for the in vivo antitumor activity against the human tumor xenograft models. CKD602 was able to imduce regression of established HT-29, WIDR and CX-1 colon tumors, LX-1 lung tumor, MX-1 breast tumor and SKOV-3 ovarian tumor as much as 80, 94, 76, 67, 87% and 88%, respectively, with comparable body weight changes to those of topotecan. Also the therapeutic margin (R/Emax: maximum tolerance dose/$ED-{58}$) of CKD602 was significantly higher than that of topotecan by 4 times. Efficacy was determined at the maximal tolerated dose levels using schedule dependent i.p. administration in mice bearing L1210 leukemia. On a Q4dx4 (every 4 day for 4 doses) schedule, the maximum tolerated dose (MTD) was 25 mg/kg per administration, which caused great weight loss and lethality in <5% tumor bearing mouse. this schedule brought significant increase in life span (ILS), 212%, with 33% of long-term survivals. The ex vivo antitumor activity of CKD602 was compared with that of topotecan and the mean antitumor index (ATI) values recorded for CKD602 were significantly higher than that noted for topotecan. From these results, CKD602 warrants further clinical investigations as a potent inhibitor of topoisomerase I.

• 한국식품과학회지
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• 제41권4호
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• pp.435-440
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• 2009

잎녹차 추출물 보다는 분말녹차 추출물의 경우가 그리고 저장된 sample보다는 fresh sample의 AChE 저해활성이 상대적으로 높았고 이는 생리활성 물질의 추출효율성과 생리활성 물질의 특성 변화 측면에서 기인되는 것으로 판단된다. 또한 본 연구팀에서 구성한 저장 조건에서, 4주간의 짧은 저장기간이 3개월 저장조건보다는 우수한 효소 저해활성도를 나타냈다. 수분활성도 측면에서는 수분활성도 0.81의 조건을 갖는 sample에서의 효과가 비교적 우수했고, 3개월 저장하는 동안의 저장온도 조건은 효소 저해 활성도에 큰 차이를 보이는 요소로 작용하지 못했다. 다만 상온이나 냉장조건 보다는 냉동상태의 저장조건이 다소 우수한 것으로 판단된다. 결국 생리활성물질을 보다 효율적으로 추출할 수 있는 녹차의 상태와 처리 또는 섭취 농도가 더욱 중요한 것으로 사료되고, 추출 효율을 증가시키기 위해서는 잎 보다는 분말의 상태가 더 우수한 것으로 판단된다. 따라서 녹차 추출물은 acetylcholine성 신경세포의 기능을 강화시켜줄 수 있는 AChE 저해제로서 활용가치가 높을 것이다.

• Parasites, Hosts and Diseases
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• 제33권3호
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• pp.211-218
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• 1995

간흡충의 병원성과 단백분해효소 활성도의 상관성을 밝히기 위하여 간흡충 추출물과 분비배설물 의 단백분해효소 활성도와 세포독성을 평가하였고 분비배설물에서 단백분해효소를 부분정제하고 생화학적 성질을 규명하였다. 여러 가지 단백분해효소 억제제를 사용하여 단백분해효소의 활성을 측정한 결과 간흡충에는 Rf값을 서로 달리하는 효소분획으로 되어있음이 관찰되었으며. 이러한 효소 분획은 azocasein을 기질로 한 활성부위 잔기 억제 실험에서 서로 상이한 활성부위잔기를 갖고 있음을 알 수 있었다. 간흡충 분비배설물의 세포독성은 단백질 농도를 $120\mu\textrm{g}/ml$까지 증가시키자 세포독성이 3배 증가했고. 이 효과는 NEM과 ntipain에 의해 억제되었다. 이 사실은 cysteine 단백 분해효소가 세포독성에 관여하는 것을 보여주고 있었다 이 단백분해효소는 최적활성치가 pH 7.5 이었다. 이 효소를 분비배설물로부터 23배 정제하였고 이때 회수율은 14.5%이었다. 부분정제한 단백분해효소의 분자량은 24 kDa이었다. 이 효소는 NEM, antipain에 의해 효소활성이 억제되었고, 동시에 세포독성도 억제되었다. 이 사실로부터 부분정제한 효소의 활성부위잔기는 cysteine이고 이 효소가 또한 분비배설되어 세포독성을 나타낸다는 것을 알 수 있었다.