• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1999년도 추계학술대회 논문집
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• pp.127-132
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• 1999

A mobile IP is proposed to support host mobility over the current Internet. One of the most important issues on the host mobility is location and routing schemes that allow mobile hosts to move effectively from one site to another. In a Mobile IP environment, frequent handoffs are likely to degrade the performance by minimizing the loss of datagrams during handoffs. The handoff scheme is using routing optimization and binding extension to improve the performance by minimizing the average transfer delay of messages and packet loss. Simulation details show the improvement of transport delays and packet loss rate.

• 대한약리학회지
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• 제21권2호
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• pp.79-89
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• 1985

심근 세포의 칼슘 조절에 중요한 역할을 하는 sarcoplasmic reticulum (SR)의 칼슘운반 능력이 허혈 심근에서 현저히 억제됨이 알려져 있다. 이와같은 허혈 심근에서의 SR 칼슘운반승력 저하에 유독성 산소 대사물이 관여할 것으로 생각되고 있으나 그 기전에 관하여는 아직 알려진 바 없다. 본 연구에서는 그 기전의 일단을 규명하기 위하여 산틴 산화효소계에 의하여 발생된 유독성 산소대사물긴 돼지 심실근에서 추출한 sarcoplasmic reticulum의 칼슘흡수 및 막지질 과산화, sulfhydryl group 그리고 단백질 변성에 미치는 영향을 관찰하여 다음과 같은 결과를 얻었다. 1) 산틴 산화 효소계와 반응시킨 sarcopl smic reticulum의 칼슘흡수는 반응시간 경과에 따라 현저히 억제되었다. 2) sarcoplasmic reticulum 막지질 과산화는 산딘 산화 효소계에 의하여 현저히 증가되었다 3) 항산화제 ${\beta}$-phenylenediamine은 막지질 과산화의 증가는 효과적으로 억제하였으나, 칼슘흡수 억제는 부분적으로 회복시켰다. 4) 산틴 산화 효소계에 의하여 SH-group은 현저히 감소되었으며, 항산화제 첨가에 의하여 그 감소가 일부 억제되었다. 5) sarcoplasmic reticulum을 DTNB로 처리하여 SH-group을 산소 대사물에 의한 산화반응으로부터 보호했을 경우 칼슘흡수의 억제가 부분적으로 방지되었다. 6) Sephadex G-200 크로마토그라피 상에서 산틴 산화효소계와 반응시킨 sarcoplasmic reticulum의 단백질분해가 관찰되었다. 7) 단백질의 polymerization은 관찰되지 않았으며, 아울러 polymerization을 억제하는 semicarbazide로 칼슘흡수 감소를 방지하지 못하였다. 이상의 결과에서 유독성 산소대사물에 의한 sarcoplasmic reticulum의 칼슘흡수 억제는 sarcoplasmic reticulum의 막지질 과산화, SH-group의 산화 및 막 반백절의 분해 등으로 초래되는 복합적인 기전으로 추정되었다.

• BMB Reports
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• 제33권3호
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• pp.228-233
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• 2000

The steady-state investigation of the mechanism of Dhydroxyisovalerate dehydrogenase was performed in order to understand this type of kinetic patterns. The initial velocity was measured with various amounts of both substrates, NADPH and 2-ketoisovalerate. Double reciprocal plots gave patterns that conversed on or near the abscissa. Binding studies indicated that NADPH bound first to the enzyme. The product $NADP^+$ was found to be a competitive inhibitor with respect to NADPH at a constant concentration of 2-ketoisovalerate. However, it showed noncompetitive inhibition against 2-ketoisovalerate at a fixed amount of NADPH. Another product, D-hydroxyisovalerate, was a non-competitive inhibitor versus NADPH and 2-ketoisovalerate at constant levels of 2-ketoisovalerate and NADPH, respectively. These results were comparable with an ordered bi-bi mechanism, in which NADPH bound first to the enzyme, followed by the binding of 2- ketoisovalerate. $NADP^+$ is the last product to be released. The ordered reaction manner of D-hydroxyisovalerate dehydrogenase from 2-ketoisovalerate to D-hydroxyisovalerate allows the accurate regulation of valine metabolism and it may lead to the regulation of total biosynthesis of enniatins in the Fusarium species.

• 대한한의학원전학회지
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• 제29권2호
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• pp.165-176
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• 2016

Objectives : This study was done to investigate the formation process of the 'The Spleen controls the blood(脾統血)' concept, to clarify what this concept means and the mechanism of its physiology. Methods : Contents including 'Controlling blood(統血)' and 'Binding blood(攝血)' were searched and analyzed in medical classics. Previous researches were applied. Results & Conclusions : The concept of 'Controlling blood' could be defined as the control of blood movement. This means that it sends blood to where it's needed, and inhibits flow from where it's excessive. 'The Spleen controls the blood' was not used as a physiologic term in early books like Huangdineijing(黃帝內經). It was first used in the 13C, then widely after the 16C. The mechanism of 'Controlling blood' could be classified as the function of 'Production', 'Distribution', and 'Adjustment' of blood. 'Production' of blood can reduce blood fever(血熱) and blood stasis(瘀血), and prevent bleeding. 'Distribution' of blood can reduce the symptoms raised by lack of blood in the five viscera and body. 'Adjustment' of blood means maintaining homeostasis and stability of the human body. Pi can adjust blood flow and prevent blood from being imbalanced.

• Bulletin of the Korean Chemical Society
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• 제21권12호
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• pp.1217-1221
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• 2000

L-alanine dehydrogenase from Bacillus subtilis exhibits allosteric kinetic properties in the presence of $ZN^{2+}$. $ZN^{2+}$ induces the binding of substrate (L-alanine) to be cooperative at pH 8.0. The effect of pH variation between pH 7.0 and pH 10.0 on the inhibition by $ZN^{2+}$ correlates with the pH effect on the $K_m$ values for L-alanine within these pH range indicating that $ZN^{2+}$ and substrate compete for the same site. No such cooperativity is induced by $ZN^{2+}$ when the reaction is carried out at pH 10. At this higher pH, $ZN^{2+}$ binds with the enzyme with lower affinity and noncompetitive with respect to L-alanine. Inhibition of L-alanine dehydrogenase by $ZN^{2+}$ depends on the ionic strength. Increase in KCI concentration reduced the inhibition, but allosteric property in $ZN^{2+}$ binding is conserved. A model for the regulatory mechanism of L-alanine dehydrogenase as a noncooperative substrate-cooperative cofactor allosteric enzyme, which is compatible in both concerted and the sequential allosteric mechanism, is proposed.

• Biomolecules & Therapeutics
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• 제29권5호
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• pp.562-570
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• 2021

Topoisomerase IIα has been a representative anti-cancer target for decades thanks to its functional necessity in highly proliferative cancer cells. As type of topoisomerase IIα targeting drugs, topoisomerase II poisons are frequently in clinical usage. However, topoisomerase II poisons result in crucial consequences resulted from mechanistically induced DNA toxicity. For this reason, it is needed to develop catalytic inhibitors of topoisomerase IIα through the alternative mechanism of enzymatic regulation. As a catalytic inhibitor of topoisomerase IIα, AK-I-191 was previously reported for its enzyme inhibitory activity. In this study, we clarified the mechanism of AK-I-191 and conducted various types of spectroscopic and biological evaluations for deeper understanding of its mechanism of action. Conclusively, AK-I-191 represented potent topoisomerase IIα inhibitory activity through binding to minor groove of DNA double helix and showed synergistic effects with tamoxifen in antiproliferative activity.

• 한국토양환경학회지
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• 제4권3호
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• pp.77-84
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• 1999

본 논문에서는 고농도의 중금속 (납, 구리)으로 오염된 세 가지의 토양을 대상으로 sequential extraction 방법을 사용하여 토양과 중금속의 차이에 따른 결합 특성을 밝혀내고자 하였다. 고농도의 납과 구리로 오염된 토양을 형태별로 추출하였을 때 토양의 특성과 중금속의 종류에 따라 다른 결과를 보였다. 납은 문화동 토양에서는 Carbonate 형태가 37.7%로 가장 높았고 농토는 Amorphous Fe oxide 형태가 23.9%, 공단 토양에서는 Exchangeable 형태가 22.9%로 나타났다. 이에 비하여 구리는 세 가지 토양에서 공통적으로 Organically bound 형태가 농토에서 26.1%, 문화동 토양은 20.4%. 공단 토양에서는 24.1%로 높게 나타났고 Carbonate 형태와 Amorphous Fe oxide형태의 비율도 높게 나타났다. 또한 Crystallized Fe oxide 형태와 Residuals 형태도 납보다 높은 비율을 나타냄으로서 구리가 납보다는 토양과 강한 결합을 형성하는 것으로 생각된다. 이러한 토양과 중금속의 결합 특성은 오염 토양의 복원시 유용한 자료가 될 수 있다.

• 분석과학
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• 제8권3호
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• pp.299-304
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• 1995

정지상으로서 N, N'-bispalmtoyl 1, 12-diaza-3, 4:9,10-dibenzo-5, 8-cyclopentadecane (hexadecyl $NtnOenH_4$)-octadecylsilanized silicas(ODS)와 이동상으로 물을 사용하여 Ba(II), Cr(II), Fe(II) 및 Cu(II)의 흡착특성을 조사하였다. 수용액상 Ba(II), Cr(II), Fe(II) 및 Cu(II)의 결합상수와 흡착도를 조사한 결과 그 순위는 Ba(II)$NtnOenH_4$-octadecylsilanized silicas(ODS)에 흡측되는 금속이온의 농도 증가는 cation chelation mechanism에 의해 설명할 수 있었다. 또한 수용액상에서 Ba(II), Cr(II), Fe(II) 및 Cu(II)이 혼합된 용액에서 Cu(II)의 분리효율이 다른 이온들에 비해서 좋게 나타남을 알 수 있었다.

• 대한약리학회지
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• 제31권2호
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• pp.219-231
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• 1995

Vasoactive intestinal polypeptide(VIP) and ${\beta}-adrenergic$ agonists have immunomodultory effects on the peripheral blood T-lymphocytes of rat through their own receptors. Both of them utilize the same signal transduction pathway. That is, the stimulatory guanine nucleotide binding protein(G protein) mediates the receptor-adenylyl cyclase coupling, producing intracellular increase of cyclic adenosine monophosphate(cAMP). In the previous experiment, propranolol, a ${\beta}-adrenergic$ receptor blocker, inhibited the VIP-induced protein phosphorylation in lymphocytes. However, propranolol could not block the effect induced by forskolin. Therefore, this study was designed to elucidate the mechanism of the inhibitory action of propranolol on the effects of VIP. Using peripheral blood lymphocytes of rats, the effect of propranolol on the receptor binding characteristics of VIP was observed. And the effects of propranolol were compared to the effects of timolol on the cAMP increase induced by isoproterenol, VIP or forskolin. The results obtained are as follows. 1) Receptor binding study showed no significant differences in the affinity or density of VIP receptor between the control and propranolol-pretreated groups. 2) VIP-induced increase of cAMP was inhibited by propranolol, but not by timolol. 3) Both propranolol and timolol suppressed the isoproterenol-induced cAMP increase. 4) Propranolol also inhibited the histamine-induced cAMP increase. 5) Propranolol did not inhibit the increase of cAMP stimulated by forskolin. 6) Lidocaine did not block the VIP-induced cAMP increase. These results show that the inhibitory mechanism of propranolol is not related to ${\beta}-adrenergic$ receptor or its membrane stabilizing effect, and it is suggested that propranolol can block the effects of VIP by inhibiting the intermediate step between the VIP receptor and adenylyl cyclase.

• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.435-441
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• 2010

We report the preparation and characterization of a new and water soluble complex of palladium(II) with 1,10- phenanthroline and butyldithiocarbamate ligands. This compound has been studied through spectroscopic techniques, $^1H$ NMR, IR, electronic spectra and elemental analysis and conductivity measurements. The complex shows 50% cytotoxic concentration ($Ic_{50}$) value against chronic myelogenous leukemia cell line, K562, much lower than that of cisplatin. Thus the mode of binding of this complex to calf thymus DNA have been extensively investigated by isothermal titration UV-visible spectrophotometry, fluorescence, gel filteration and other methods. UV-visible studies show that the complex exhibits cooperative binding with DNA and remarkably denatures the DNA at extremely low concentration ($~13\;{\mu}M$). Fluorescence studies indicate that the complex intercalate into DNA. Gel filtration studies suggest that the binding of Pd(II) complex with DNA is strong enough that it does not readily break. In these interaction studies, several thermodynamic and binding parameters are also determined which may reflect the mechanism of action of this type of compound with DNA.