• Bulletin of the Korean Chemical Society
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• 제18권9호
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• pp.922-928
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• 1997

The conformational transition of poly(L-proline) (PLP), Form Ⅱ → Form Ⅰ and the intermolecular aggregation of the product, Form Ⅰ, during and after the transition in water-propanol (1:7, 1:9, 1:15.7, and 1:29 v/v) were studied. For the study, the viscosity change and excess light scattering intensity were measured in the course of the transition which was determined by the Form Ⅰ fraction, fI of the sample solution. For the PLP sample of molecular weight Mv=31,000 the experimental results show that the reaction course is roughly divided into three regions: in the first region [fI=0.27 to 0.40 (- [α]D=400 to 330)], the conformational change of Form Ⅱ → Form Ⅰ occurs with decrease of viscosity, in the second region [fI=0.40 to 0.80 (- [α]D=330 to 120)], a partial side-by-side (p-S-S) type aggregation in which Form Ⅰ blocks interact with each other, which induces the increase of viscosity, starts to occur, and in the third region [fI=0.80 to 1.00 (- [α]D=120 to 15)], a side-by-side type (raft like) aggregation of Form Ⅰ or an end-to-end (E-E) type aggregation occurs according to the solvent situation, i.e., in a water-rich medium [water-propanol (1:9 or 1:7 v/v)], the (S-S) type aggregation with a gross decrease in viscosity occurs while in a water-poor medium [water-propanol (1:29 or 1:15.7 v/v), the (E-E) type aggregation with a large increase in viscosity occurs. The (S-S) type aggregation was promoted at high temperatures. Based on the structure of PLP, a reasonable mechanism for the (p-S-S) and (S-S) aggregation which occurs with the transition of Form Ⅱ → Form Ⅰ is considered. The suggested mechanism was also supported by the result of chain length effect of PLP for the aggregation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.605-611
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• 2001

A numerical technique for simulating the aggregation of charged particles was presented with a Brownian dynamic simulation in the free molecular regime. The Langevin equation was used for tracking each particle making up an aggregate. A periodic boundary condition was used for calculation of the aggregation process in each cell with 500 primary particles of 16 nm in diameter. We considered the thermal force and the electrostatic force for the calculation of the particle motion. The morphological shape of aggregates was described in terms of the fractal dimension. The fractal dimension for the uncharged aggregate was $D_{f}=1.761$. The fractal dimension changed slightly for the various amounts of bipolar charge. However, in case of unipolar charge, the fractal dimension decreased from 1.641 to 1.537 with the increase of the average number of charges on the particles from 0.2 to 0.3 in initial states.

• BMB Reports
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• 제41권9호
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• pp.635-639
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• 2008

Acrolein is a highly reactive by product of lipid peroxidation and individuals with neurodegenerative disorders have been shown to contain elevated concentrations of this molecule in the brain. In the present study, we examined the pattern of neurofilament-L (NF-L) modification elicited by acrolein. When NF-L was incubated with acrolein, protein aggregation occurred in a acrolein concentration-dependent manner. Exposure of NF-L to acrolein also led to the generation of protein carbonyl compounds. Through the addition of free radical scavengers we observed a significant decrease in acrolein-mediated NF-L aggregation. These results indicate that free radicals may be involved in the modification of NF-L by acrolein. In addition, dityrosine crosslink formation was observed in acrolein-mediated NF-L aggregates and these aggregates displayed thioflavin T reactivity, reminiscent of amyloid. This study suggests that acrolein-mediated NF-L aggregation might be closely related to oxidative reactions, thus these reactions may play a critical role in neuro-degenerative diseases.

• Journal of Photoscience
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• 제9권2호
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• pp.66-69
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• 2002

Zinc chlorin 1 possessing tertiary 3$^1$_hydroxy and 13$^1$-oxo groups was synthesized as a model for the antenna chlorophylls of photosynthetic green bacteria. Self-aggregation of 1 in nonpolar organic solvents was examined and compared to 2 and 3 possessing a secondary and primary 3$^1$_hydroxy group, respectively. Zinc chlorin 1 self-aggregated in I％(v/v) CH$_2$Cl$_2$-hexane to form oligomers and showed a red-shifted Qy maximum at 704 nm compared to the monomer (648 nm in CH$_2$CI2$_2$). This red-shift is larger than that of 3$^1$S-2 (648 to 697 nm) and comparable to that of3$^1$R-2 (648 to 705 nm), but smaller than that of 1 (648 to 740 nm), indicating that while a single 3$^1$-methyl group (primary to secondary OH) suppressed tight and/or extended aggregation, the additional 3$^1$-methyl group (secondary to tertiary OH) did not further suppress aggregation. The relative stability of the aggregates was in the order 3> 3$^1$R-2∼ 1 > 3$^1$S-2 as determined by visible spectral analyses. Molecular modeling calculations on oligomers of zinc chlorins 1, 3$^1$ R-2 and 3 gave similar well-ordered energy-minimized structures, while 3 stacked more tightly than 3$^1$ R- 2 and 1. In contrast, 3$^1$S-2 gave a relatively disordered (twisted) structure. The calculated oligomeric structures could explain the visible spectral data of 1-3 in nonpolar organic solvents. Moreover, self- aggregation of synthetic zinc 13$^1$_oxo-hlorins 4-6 possessing a 2-hydroxyethyl, 3-hydroxypropyl and 3- hydroxy-I-propenyl group at the 3-position in nonpolar organic solvents was discussed.

• Applied Biological Chemistry
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• 제29권2호
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• pp.198-206
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• 1986

정제인삼(精製人蔘)사포닌의 수용액을 분자투석막(分子透析膜)(분자량(分子量) 12000)을 통(通)하여 투석(透析)하거나 Bio-Gel P-2(분자량(分子量) $200{\sim}2000$)gel을 통과시켜 분취(分取)하고 HPLC로 ginsenoside를 분석(分析)하였다. Ginsenoside는 분자결합양상(分子結合樣相)과 분자내(分子內) 친수성기(親水性基)의 공간배열(空間配列)에 따라 3군(群)으로 분류(分類)되었다. 제(第) I 군(群)은 거대(巨大)미셀 형성자(形成者)로 결합분자수(結合分子數)가 10이상이며 I면친수기형(面親水基形)이고 panaxadiol인 $Ginsenoside\;Rb_1$, $Rb_2$, Rc 및 Rd가 포함된다. 제(第)II군(群)은 소(小)미셀형성자(形成者)로 결합분자수(結合分子數)가 10이상(以上)에서 1까지이고 불완전(不完全) 양면친수기형(兩面親水基形)이며 triol인 $Rg_2$와 Rf 및 diol인 $Rg_3$가 포함된다. 제(第)III군(群)은 단분자(單分子)로 존재(存在)하며 양면친수기형(兩面親水基形)이고 triol인 Re와 $Rg_1$을 포함한다.

• 대한기계학회논문집B
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• 제36권8호
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• pp.873-876
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• 2012

Ionic Liquids (ILs) 는 표준상태에서 액체이온으로 존재하는 물질로 여러 가지 방법으로 다양한 특성을 띄게 할 수 있다. 이런 성질을 적절하게 이용하여 계면활성제 등 다양한 분야로의 응용이 가능하다. ILs의 한 종류인 1-10-alkyl-3-methylimidazolium bromide([C10mim][Br]) 은 특정한 환경에서 양친매성을 가진다. 이번 논문에서 우리는 분자동역학을 이용하여 수용액에서의 [C10mim][Br]의 응집 거동에 대한 연구를 진행하였다. 정준모듬(canonical ensemble)을 이용하여 모사 간 시스템의 부피와 온도를 일정하게 유지시키고 5ns 동안의 전산모사를 통하여 얻은 radial distribution function(RDF)을 이용하여 [C10mim][Br]과 물 분자간의 상호작용 및 그 분포의 특성에 대하여 논의하였다. 분자동역학적 계산을 위하여 LAMMPS 코드를 사용하였고, VMD 코드를 이용하여 후처리(post processing)을 진행하였다.

• Journal of Microbiology and Biotechnology
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• 제8권6호
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• pp.663-668
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• 1998

Several neurodegenerative diseases such as Huntington's disease, dentatorubralpallidoluysian atrophy, spinobulbar muscular atrophy, Machado-Joseph disease, and spinocerebellar ataxias type 1 are associated with the aggregation of expanded glutamine repeats within their proteins. Generally, in clinically affected individuals, the expansion of the polyglutamine sequences is beyond 40 residues. To address the length of polyglutamine that forms aggregation, we have constructed plasmids encoding glutathione S-transferase (GST) Machado-Joseph disease gene fusion proteins containing polyglutamine and investigated the formation of aggregates in E. coli. Surprisingly, even $(Gin)_8$, in the normal range as well as $(Gin)_{65}$ in the pathogenic range enhanced the formation of insoluble protein aggregates, whereas $(Ser)_8$, and $(Aia)_8$, did not form aggregates. Our results indicate that the formation of protein aggregates in GST-polyglutamine proteins is specifically mediated by the polyglutamine repeat sequence within their protein structure. Our study may contribute to the understanding of the molecular mechanism of the formation of protein aggregates in neurodegenerative disorders and the development of preventative strategies.

• 대한임상검사과학회지
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• 제51권1호
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• pp.34-41
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• 2019

혈소판 응집은 혈관 손상의 경우 지혈 플러그 형성에 필수적이다. 그러나, 과도한 혈소판 응집은 혈전증, 죽상 동맥 경화증 및 심근 경색과 같은 순환기 장애를 일으킬 수도 있다. Scopoletin은 Scopolia 또는 Artemisia 속 식물의 뿌리에서 발견되는 성분으로, 항응고 및 항말라리아 작용을 가지는 것으로 알려져 있다. 본 연구는 collagen에 의해 유발된 혈소판 응집에 scopoletin이 미치는 영향을 조사하였다. Scopoletin은 활성화된 혈소판에서 생성되는 응집 유도 분자인 thromboxane $A_2$ ($TXA_2$) 및 세포 내 $Ca^{2+}$ 동원 ($[Ca^{2+}]_i$)의 하향 조절을 통해 항 혈소판 효과를 나타내었다. 한편, scopoletin은 세포 내 $Ca^{2+}$-길항제인 것으로 알려져 있는 cyclic adenosine monophosphate(cAMP)와 cyclic guanosine monophosphate (cGMP) 수치를 증가시켰다. 특히, scopoletin은 cGMP보다 cAMP 수준을 강력하게 증가함으로써 콜라겐에 의해 유발된 사람 혈소판 응집에서의 ${\alpha}IIb/{\beta}_3$에 대한 피브리노겐 결합을 억제하였다. 또한, scopoletin은 용량 의존적으로 collagen에 의해 증가된 adenosine trisphosphate (ATP)의 방출을 억제하였다. 이 결과는 혈소판 내 과립 분비를 통한 응집 증폭작용이 scopoletin에 의해 억제되었음을 의미한다. 따라서, 본 연구는 scopoletin이 강력한 항혈소판 효과를 가지며 혈소판-유래의 혈관 질환을 예방할 가능성이 크다는 것을 입증하였다.

• 생약학회지
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• 제51권3호
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• pp.151-157
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• 2020

When blood vessels are damaged, a rapid hemostatic reaction occurs to minimize blood loss and maintain normal circulation. Platelet activation and aggregation is essential in this process. However, excessive platelet aggregation or abnormal platelet aggregation may be the cause of cardiovascular disease, such as thrombosis, stroke and atherosclerosis. Therefore, it is important to prevent and treat cardiovascular disease by finding substances that can regulate platelet activation and suppress aggregation reactions. Isoscopoletin, which is mainly found in the roots of plants Artemisia or Scopolia, has been reported to have potential pharmacological effects on anticancer and Alzheimer's disease, but its role and mechanisms for platelet aggregation and thrombus formation are unknown. This study confirmed the effect of isoscopoletin on major regulation of collageninduced human platelet aggregation, TXA₂ production and intracellular granular secretion (ATP and serotonin release). In addition, the effects of isoscopoletin on phosphorylation of phosphorylated proteins PI3K/Akt and MAPK involved in signal transduction in platelet aggregation was studied. As a result, isoscopoletin significantly inhibited the phosphorylation of PI3K/Akt and MAPK, significantly inhibiting platelet aggregation through TXA₂ production and intracellular granular secretion (ATP and serotonin release). Therefore, we suggest that isoscopoletin is an anti-platelet substance that regulates phosphorylation of phosphorus proteins such as PI3K/Akt and MAPK and is valuable as a preventive and therapeutic agent for platelet-derived cardiovascular disease.

• Journal of Applied Biological Chemistry
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• 제66권
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• pp.221-226
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• 2023

혈소판의 적절한 활성화와 응집이 필요하지만 과도하거나 비정상적인 응집은 뇌졸중, 혈전증, 동맥경화증과 같은 심혈관 질환을 유발할 수 있다. 따라서 이러한 질병을 예방하고 치료하기 위해서는 혈소판 응집을 조절하거나 억제할 수 있는 물질을 찾는 것이 중요하다. 여러 연구에서 Panax 인삼의 특정 ginsenoside 화합물이 혈소판 응집을 억제할 수 있음이 알려져 있다. 이들 화합물 중 Panax ginseng의 Rk3 (G-Rk3)는 혈소판 응집 억제의 기전이 불확실 하기에 이를 밝히기 위한 연구가 필요하다. G-Rk3는 cAMP의 양을 강하게 증가시켰고 cAMP 의존성 kinase의 기질인 VASP 및 IP3R의 인산화를 유도했다. 또한, G-Rk3의 효과는 PI3K/Akt 인산화의 억제를 일으켜 세포 내 과립의 분비를 감소시켰다. 궁극적으로 G-Rk3는 혈소판 응집을 효과적으로 억제하였다. 따라서 우리는 과도한 혈소판 응집으로 인한 심혈관 질환의 예방 또는 치료제로서의 G-Rk3의 가능성을 제안한다.