• 대한화학회지
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• 제29권3호
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• pp.304-310
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• 1985

송아지 흉선 nucleohistone의 DNase 1에 對한 susceptibility와 相互作用의 cooperativity에 미치는 spermine의 效果를 nucleostone의 構造變移와 關聯시켜 調査하였다. 이들 data로 부터 nucleohistone은 遊離 DNA와는 對照的으로 spermine에 의하여 monomoclecular condensation을 일으키지 않고 intermolecular aggregation을 이루며 nucleohistone의 DNase 1과의 相互作用 cooperativity가 spermine에 의하여 增加됨을 推理할 수 있다. Nucleohistine의 histone 部分의 cooperativity에 關한 機能的 役割을 究明하기 위하여 histone 部分을 단실化시킨 DNS-nucleohistone을 製造하여 DNase 1 과의 相互作用을 調査하여 보았는바 negative cooperativity로 나타났다. 이로 부터 nucleohistone의 histone部分은 nucleohistone의 cooperativity에 影響을 미치리라고 推理할 수 있다.

• 한국동물학회지
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• 제31권2호
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• pp.81-86
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• 1988

생쥐혹은 돼지의 난자-난구 복합체를 인공배양하면서 뇌하수체호르몬 혹은 세포내 cAMP의 농도를 높이는 시약을 사용하여 난자의 성숙과 난구세포의 분산을 조절하고 이 때 두 세토들 사이에 상호협력(metabolic cooperativity)관계가 어떻게 변하는지를 조사하여 보았다. 생귀와 돼지의 난구세포들은 뇌하수체호르몬이나 cAMP의 증가에 의해 분산이 유도됨과 동시에 배양액 내에서 있는 uridine의 흡수가 크게 촉진되었다. (대조군의 약 4배). 그러나 난구세포에 흡수된 uridine이 난자로 전달되는 물질이동율(transfer ratio)은 대조군과 같이 시간이 지남에 따라 감소하였으며 cAMP의 영향도 거의 받지 않았다. 또한 물질이동율의 감소는 난구세포의 부산여부나 난자의 성숙(핵붕괴) 여부에 크게 영향을 받지 않았다.단지 생쥐의 경우 호르몬에 의해 물질이동율의 감소가 더욱 두드러지게 나타나는 경우를 볼수 있었다. 따라서 물질이동율의 변화가 난구세포의 분산이나 난자의 성숙과 직접 관련이 없는 것으로 보여지며 두 세포들 사이의 metabolic cooperativity가 난자의 성숙조절에 중요한 요인이 되지 않는다는 것을 알았다.

• Bulletin of the Korean Chemical Society
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• 제22권7호
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• pp.693-698
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• 2001

Ab initio density functional calculations on the structural isomers, the hydration energies, and the hydrogen bond many-body interactions for gauche-, trans-protonated ethylenediamine-(water)3 complexes (g-enH+(H2O)3, t-enH+(H2O)3) have been performed. The structures and relative stabilities of three representative isomers (cyclic, tripod, open) between g-enH+(H2O)3 and t-enH+(H2O)3 are predicted to be quite different due to the strong interference between intramolecular hydrogen bonding and water hydrogen bond networks in g-enH+(H2O)3. Many-body analyses revealed that the combined repulsive relaxation energy and repulsive nonadditive interactions for the mono-cyclic tripod isomer, not the hydrogen bond cooperativity, are mainly responsible for the greater stability of the bi-cyclic isomer.

• BMB Reports
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• 제31권1호
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• pp.25-30
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• 1998

Kinetic studies of L-Alanine dehydrogenase from Bacillus subtilis-catalyzed reactions in the presence of $Zn^{2+}$ were carried out. The substrate (L-alanine) saturation curve is hyperbolic in the absence of the metal ion but it becomes sigmoidal when $Zn^{2+}$ is added to the reaction mixture indicating the positive cooperative binding of the substrate in the presence of zinc ion. The cooperativity of substrate binding depends on the xinc ion concentration: the Hill coefficients ($n_H$) varied from 1.0 to 1.95 when the zinc ion concentration varied from 0 to $60\;{\mu}m$. The inhibition of AlaDH by $Zn^{2+}$ is reversible and noncompetitive with respect to $NAD^+$ ($K_i\;=\;5.28{\times}10^{-5}\;M$). $Zn^{2+}$ itself binds to AlaDH with positive cooperativity and the cooperativity is independent of substrate concentration. The Hill coefficients of substrate biding in the presence of $Zn^{2+}$ are not affected by the enzyme concentration indicating that $Zn^{2+}$ binding does not change the polymerization-depolymerization equilibria of the enzyme. Among other metal ions, $Zn^{2+}$ appears to be a specific reversible inhibitor inducing conformational change through the intersubunit interaction. These results indicate that $Zn^{2+}$ is an allosteric competitive inhibitor and substrate being a non-cooperative per se, excludes the $Zn^{2+}$ from its binding site and thus exhibits positive cooperativity. The allosteric mechanism of AlaDh from Bacillus subtilis is consistent with both MWC and Koshland's allosteric model.

• 한국자기공명학회논문지
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• 제1권2호
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• pp.112-125
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• 1997

It has been demonstrated that mutant Hemoglobins (Hb) which have an altered ${\alpha}$1${\beta}$2 subunit interface can be designed. A compensatory mutation for a naturally occurring abnormal human Hb, Hb Kempsey (${\beta}$99Asp\longrightarrowAsn), has been designed, and this mutation allowed the molecule to regain its allosteric response. The calculated values for the difference in the free energy of cooperativity show excellent agreement with experimentally determined thermodynamic values, suggesting that the molecular dynamics simulation results can be used to obtain information about the specific interactions which contribute to the total free energy of cooperativity. These results provide encouragement to begin a systematic investigation of the molecular basis of the subunit interactions between the ${\alpha}$1 and ${\beta}$2 chains of Hb A by designing appropriate r Hbs. These studies could lead to the design of Hbs with desired cooperativity in the oxygenation process and to the restoration of functional properties of abnormal hemoglobins associated with hemoglobinopathies. Thus, the present results also have the implications in using gene therapy to treat patients with hemoglobinpathies.

• 한국응용곤충학회지
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• 제61권1호
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• pp.117-128
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• 2022

본 연구는 피레스로이드계 살충제인 퍼메트린이 Heliothis virescens의 중추신경세포의 나트륨채널에 어떻게 작용하는 가를 전기생리학적으로 관찰하였다. 퍼메트린은 나트륨채널의 꼬리전류(I_Na-tail)를 지속적으로 증가시켰으며 이러한 비정상적인 나트륨 전류증가가 나방류의 신경계에 과도한 흥분을 일으겨 살충작용을 하는 것으로 생각된다. 이러한 살충작용은 전갈독과 함께 사용했을때 약 8배의 증가가 있었음을 확인하였다. 전갈독이 살충제의 독성을 강화하는 분자생리학적 기전연구가 계속되면 해충방제에 많은 기여를 할 것으로 생각된다.

• Bulletin of the Korean Chemical Society
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• 제32권3호
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• pp.1045-1047
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• 2011

• 대한화학회지
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• 제29권5호
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• pp.533-538
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• 1985

Spermine에 의하여 誘發되는 凝縮 DNA 構造의 安定化에 있어서 hydrophobic interaction의 重要性을 試驗하기 위하여 spermine-DNA 複合體의 異例的 吸光度-溫度 樣相에 미치는 urea의 效果를 調査하였다. 그 結果 異例的 吸光度-溫度 樣相의 downward peak(trough) 領域에 이르는 相變移에 對한 cooperativity, enthalpy, midpoint의 값들이 Tm 領域의 값들 보다 urea에 敏感한 影響을 받았으며, urea의 濃度 增加에 따라 downward peak가 점차 사라졌다. 이 data는 異例的 吸光度-溫度 樣相을 構成하는 downward peak가 spermine에 의하여 誘發되는 hydrophobic interaction에 의한 凝縮된 tertiary structure의 形成을 나타내고 있다고 불 수 있다.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제9권1호
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• pp.23-34
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• 2004

Escherichia coli transcription termination factor Rho catalyzes the unwinding of RNA/DNA duplex in reactions that are coupled to ATP binding and hydrolysis. Fluorescence stopped-flow methods using ATP and the fluorescent 2'(3')-O-( N-methylanthraniloyl) derivatives (mant-derivatives) of ATP and ADP were used to probe the kinetics of nucleotide binding to and dissociation from the Rho-RNA complex. Presteady state nucleotide binding kinetics provides evidence for the presence of negative cooperativity in nucleotide binding among the multiple nucleotide binding sites on Rho hexamer. The binding of the first nucleotide to the Rho-RNA complex occurs at a bimolecular rate of 3.6${\times}$10$\^$6/ M$\^$-1/ sec$\^$-1/ whereas the second nucleotide binds at a slower rate of 4.7${\times}$10$\^$5/ M$\^$-1/ sec$\^$-1/ at 18$^{\circ}C$, RNA complexed with Rho affects the kinetics of nucleotide interaction with the active sites through conformational changes to the Rho hexamer, allowing the incoming nucleotide to be more accessible to the sites. Adenine nucleotide binding and dissociation is more favorable when RNA is bound to Rho, whereas ATP binding and dissociation step in the absence of RNA occurs significantly slower, at a rate ∼70- and ∼40-fold slower than those observed with the Rho-RNA complex, respectively.

• BMB Reports
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• 제45권12호
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• pp.748-753
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• 2012

A sequence of 10 amino acids at the C-terminus region of methylglyoxal synthase from Escherichia coli (EMGS) provides an arginine, which plays a crucial role in forming a salt bridge with a proximal aspartate residue in the neighboring subunit, consequently transferring the allosteric signal between subunits. In order to verify the role of arginine, the gene encoding MGS from a thermophile species, Thermus sp. GH5 (TMGS) lacking this arginine was cloned with an additional 30 bp sequence at the 3'-end and then expressed in form of a fusion TMGS with a 10 residual segment at the C-terminus ($TMGS^+$). The resulting recombinant enzyme showed a significant increase in cooperativity towards phosphate, reflected by a change in the Hill coefficient (nH) from 1.5 to 1.99. Experiments including site directed mutagenesis for Asp-10 in TMGS and $TMGS^+$, two dimentional structural survey, fluorescence and irreversible thermoinactivation were carried out to confirm this pathway.