• 한국환경보건학회지
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• 제38권4호
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• pp.351-359
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• 2012

Objectives: This study was conducted in order to investigate the specific correlation between physicochemical properties and bioactivity in ecdysteroids found in living organisms. Methods: The examined steroidal compounds were classified into three groups according to their relevance to ecdysone activity. Each compound molecule was completely drawn to automatically calculate its physicochemical parameters and docked against 20-hydroxyecdysone to calculate the total distance. Electronic charge distribution was also observed for each molecule. All procedures were conducted using a computational chemistry program. Results: Ecdysone agonists showed different ranges of parameter values, such as log P, hydrophilic-lipophilic balance (HLB), solubility parameter (SP), hydrophilic surface (HPS), hydrogen bond (HB) and Kappa 2, when compared with antagonists and steroids without ecdysone activity. They also showed a similar electronic charge distribution that is significantly different from the electron charge distribution of antagonists and steroids without ecdysone activity. The total distance values of agonists, estimated by docking them with 20-hydroxyecdysone, were relatively small but showed no correlation with binding affinity with receptor ligand. Conclusions: These results suggest that physicochemical properties such as steric and electronic effects, hydrophobicity and hydrogen bonding may operate in combination to determine the binding activity of ecdysteroids to the receptor protein.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.1020-1028
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• 2012

This work compares various models for geminate reversible diffusion influenced reactions. The commonly utilized contact reactivity model (an extension of the Collins-Kimball radiation boundary condition) is augmented here by a volume reactivity model, which extends the celebrated Feynman-Kac equation for irreversible depletion within a reaction sphere. We obtain the exact analytic solution in Laplace space for an initially bound pair, which can dissociate, diffuse or undergo "sticky" recombination. We show that the same expression for the binding probability holds also for "mixed" reaction products. Two different derivations are pursued, yielding seemingly different expressions, which nevertheless coincide numerically. These binding probabilities and their Laplace transforms are compared graphically with those from the contact reactivity model and a previously suggested coarse grained approximation. Mathematically, all these Laplace transforms conform to a single generic equation, in which different reactionless Green's functions, g(s), are incorporated. In most of parameter space the sensitivity to g(s) is not large, so that the binding probabilities for the volume and contact reactivity models are rather similar.

• 영어어문교육
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• 제4호
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• pp.207-228
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• 1998

This study investigated how Korean learners of English acquired the English reflexives. There is emphasis on the effects of the GCP and PAP(Wexler and Manzini, 1987). The purpose is to examine the major hypothesis that L2 learners are still constrained by Universal Grammar (UG), despite the influence of the parameter setting of their native language as well as the non-operation of the Subset Principle. The experimental group consisted of 30 middle school students (age 14-15), 30 high school students (age 16-17), and 30 university students (age 18-19) as well as 20 ESL students (age 16) studying English in the USA. Twenty native speakers of English served as a control group. The subjects responded to a test on reflexives that used a multiple-choice grammaticality judgement task. Findings show that L2 learners transfer their L1 parameter setting and, as a result, make errors in the choice of antecedents for reflexives. Therefore, I argue that the L2 learner is still constrained by UG.

• 한국자기공명학회논문지
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• 제8권2호
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• pp.77-85
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• 2004

$^1$H-detected $^{15}$N NMR was employed to investigated the effect of mutation (Y14F) on the dynamic properties of catalytic residues in ${\Delta}^5$-3- ketosteroid isomerase (KSI) from Conamonas testosteroni. In particular, the backbone dynamics of the catalytic residues have been studied in free enzyme and its complex with a steroid ligand, 19-nortestosterone hemisuccinate, by $^{15}$N relaxation measurements. The relaxation data were analyzed using the model-free formalism to extract the model-free parameters (S$^2$, ${\tau}_e$, and R$_{ex}$). The results show that the mutation causes a significant decrease in the order parameter (S$^2$) for the catalytic residues of free Y14F KSI, presumably due to breakdown of the hydrogen bond network by mutation. In addition, the order parameters of Phe-14 and Asp-99 increased slightly upon ligand binding, indicating a slight restriction of the high-frequency (pico- to nanosecond) internal motions of the residues in the complexed Y14F KSI, while the order parameter of Tyr-55 decreased significantly upon ligand binding.

• Journal of Microbiology and Biotechnology
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• 제6권4호
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• pp.250-254
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• 1996

MR-387A [(2S, 3R)-2-hydroxy-3-amino-4-phenylbutanoyl-L-valyl-L-prolyl-(2, 4-trans)- L-4-hydroxy-proline] reversibly inhibits aminopeptidase N (BC 3.4.11.2) in a process that is remarkable for its unusual degree of time dependence. The time required to inactivate the enzyme by 50$%$ ($t_{1/2}$) for establishing steady-state levels of $EI^*$complex was approximately 5 minutes. This indicates that the inhibition is a slow-binding process. In dissociation experiments of $EI^*$ complex, enzymic activity was regained slowly in a quadratic equation, indicating that the inhibition of aminopeptidase N by MR-387A is tight-binding and reversible. Thus, the binding of MR-387A by aminopeptidase N is slow and tight, with $K_{i}$ (for initial collision complex, EI) and $K_i{^*}$ (for final tightened complex, $EI^*$) of $2.2\times10^{-8}$ M (from Lineweaver-Burk plot) and $4.4\times10^{-10}$ M (from rate constants), respectively. These data indicate that MR-387A and aminopeptidase N are bound approximately 200-fold more tightly in the final $EI^*$complex than in the initial collision EI complex.

• 대한핵의학회지
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• 제16권2호
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• pp.59-61
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• 1982

To evaluate the diagnostic value of the ratio of serum tyroxine$(T_4)$/thyroxine-binding globulin (TBG) for the thyroid status in pregnancy and newborn serum thyroxine, TBG, triiodothyronine, and free thyroxine levels were radioimmunoassayed in normal pregnant women at each of the trimesters, and the calculated serum $T_4/TBG$ ratios were compared with other parameters such as $T_3/TBG$ ratio and free $T_4/TBG$ ratio and free $T_4/TBG$ ratio. Serum $T_4$ levels were elevated with the propotionate increase in TBG levels during pregnancy, leading to the nearly constant value of serum $T_4/TBG$ ratios as in normal non-pregnant controls. In contrast, serum $T_3/TBG$ and free $T_4/TBG$ ratios varied considerably during pregnancy. In newborn, $T_4$ levels were nearly not changed with compared non-pregnant control value and TBG levels were elevated. The results indicate that serum $T_4/TBG$ ratio is a better parameter than others in evaluating the thyroid status during pregnancy and but newborn is a no better.

• Clinical and Experimental Reproductive Medicine
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• 제25권1호
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• pp.1-8
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• 1998

항정자항체의 종류 및 존재부위가 정액성상 및 수정능력에 미치는 영향을 조사하였다. 항정자항체의 종류 및 존재부위는 immunobead binding test에 의하여 시행하였으며, 정자와 수정능력은 투명대제거 햄스터 난자 침입법에 의하여 시행하였다. 항정자항체는 정자수, 운동성 및 운동지수에 악영향을 끼쳤으며, 수정능력에도 악영향을 끼쳤다. 항정자항체의 존재부위에 따른 차이는 보이지 않았다. 항정자항체 IgG가 정자두부 혹은 정자미부에 존재할 경우 및 항정자항체 IgA가 정자미부에 존재할 경우 수정능력을 크게 감소시켰다.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1994년도 춘계학술대회 and 제3회 신약개발 연구발표회
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• pp.307-307
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• 1994

본 실험에서는 유전자 재조합으로 제조한 〔$^{125}$/I〕-labeled human GM-CSF를 사용하여 GM-CSF의 HL-60 cell의 표면에 존재하는 GM-CSF 수용체의 특성을 밝히고 수용체에 대한 binding parameter를 확인하고 Immunex(미국) 사에서 제조한 Prokine(Sargramostim)과 Sigma사에서 구입한 GM-CSF(C-9666)를 표준물질로 하여 (주) Lucky에서 제조한 GM-CSF(LBD-005)의 수용체에 대한 결합율을 측정, 각각 비교하고자 하였다. 한편 LBD-005는 glycosylation된 form과 안된 form의 혼합물이므로 당화의 정도가 수용체에 대한 결합에 미치는 영향을 알아보기 위해 glycosylated form과 혼합물(LBD-005)의 수용체에 대한 결합율을 측정 비교하였다.

• Journal of Microbiology and Biotechnology
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• 제20권9호
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• pp.1283-1287
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• 2010

In eukaryotes, eRF3 participates in translation termination and belongs to the superfamily of GTPases. In this work, the dissociation constants for nucleosides bound to Euplotes octocarinatus eRF3 in the presence and absence of eRF1a were determined using fluorescence spectra methods. Furthermore, a GTP hydrolyzing assay of eRF3 was carried out using an HPLC method, and the kinetic parameters for GTP hydrolysis by eRF3 were determined. Consistent with data from humans, the results showed that eRF1a promoted the binding of GTP to eRF3 and the GTP hydrolyzing activity of eRF3. However, in contrast to the lack of GTP binding in the absence of eRF1 in human eRF3, the E. octocarinatus eRF3 was able to bind GTP by itself. The nucleotide binding affinity of the E. octocarinatus eRF3 also differed from the human data. A structure model and amino acid sequence alignment of potential G domains indicated that these differences may be due to valine 317 and glutamate 452 displacing the conserved glycine and lysine involved in GTP binding.

• KSBB Journal
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• 제18권2호
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• pp.100-106
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• 2003

의학, 약학적으로 작용이 뛰어난 약리성분이 인체 내에서 상처 부위에 얼마나 빨리 도달하여 치료를 하는지를 알기 위하여 혈장 단백질과 약리성분의 결합력을 연구하는 새로운 연구 분야가 HPFA이다. 본 연구는 인체 내에 존재하는 혈장단백질과 항암제로서 알려져 있는 (S)-perillyl alcohol의 결합력과 결합 매개변수를 구하기 위하여 on-line frontal analysis HPLC system을 적용하였다. Develosil 100 Diol 5 (10 cm $\times$ 4.6 mm I.D.)의 HPFA 컬럼을 이용하였고, 이동상은 인산완충용액(pH = 7.4, I = 0.17)을 이용하였다. UV wavelength 205 nm에서 실험을 수행하였고, 주입 부피는 본 실험 조건인 혈장 단백질이 350 rM일 경우에 최대의 혈장 단백질과 결합되지 않은 약리성분의 농도를 갖게 되는 600 ${\mu}\ell$으로 정하였다. Scatchard analysis를 통한 연구 결과로 혈장 단백질인 HSA와 (S)-perillyl alcohol의 결합 매개변수(K)와 단위 HSA에 대한 S-POH의 결합 위치의 수(n)는 각각 K : 2.05 $\times$ $10^{6}$ [M$^{-1}$], n : 0.00428로 실험적으로 구하였다