• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2283-2287
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• 2007

Amyloid fibril formation of amyloid β/A4 protein (Aβ) is critical to understand the pathological mechanism of Alzheimer's disease and develop controlling strategy toward the neurodegenerative disease. For this purpose, dequalinium (DQ) has been employed as a specific modifier for Aβ aggregation and its subsequent cytotoxicity. In the presence of DQ, the final thioflavin-T binding fluorescence of Aβ aggregates decreased significantly. It was the altered morphology of Aβ aggregates in a form of the bundles of the fibrils, distinctive from normal single-stranded amyloid fibrils, and the resulting reduced β-sheet content that were responsible for the decreased fluorescence. The morphological transition of Aβ aggregates assessed with atomic force microscope indicated that the bundle structure observed with DQ appeared to be resulted from the initial multimeric seed structure rather than lateral association of preformed single-stranded fibrils. Investigation of the seeding effect of the DQ-induced Aβ aggregates clearly demonstrated that the seed structure has determined the final morphology of Aβ aggregates as well as the aggregative kinetics by shortening the lag phase. In addition, the cytotoxicity was also varied depending on the final morphology of the aggregates. Taken together, DQ has been considered to be a useful chemical probe to control the cytotoxicity of the amyloid fibrils by influencing the seed structures which turned out to be central to develop therapeutic strategy by inducing the amyloid fibrils in different shapes with varied toxicities.

• Composites Research
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• 제12권6호
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• pp.53-64
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• 1999

LCP원섬유(fibril)와 폴리아미드6 (PA6)수지로 사출성형된 복합재료 박판(molded thin composite plaques)의 미세구조와 굽힘강도에 대한 에폭시수지 함유율의 효과를 살펴보았다. 성형은 LCP원섬유의 용융점 이하에서 하였으며 이렇게 만들어진 판재는 횡방향 배향을 보이는 두께 $65-120{\mu\textrm{m}}$의 표피층(surface skin layer), 유동방향과 거의 일치하는 배향을 보이는 표피아래층(sub-skin layer), 아크형 곡선유동형태를 보이는 심층(core layer)으로 구성되어 있었다. 에폭시함유율이 달라도 각 층의 미세구조방향은 유사하였으나 에폭시함유율이 증가함에 따라 LCP영역(domain)이 원섬유상에서 층상구조로 변했고 거시적 파괴진로(fracture path)는 인장형에서 전단형으로 바뀌었다. 또한 에폭시 4.8vol%에서 가장 우수한 굽힘강도와 파단변형율을 보였다. 굽힘강도를 수치해석한 결과 에폭시성분을 복합재에 부가하면 각 층의 두께와 미세구조 같은 기하학적인 형태가 변하면서 각 층 자체의 탄성계수와 강도가 열등화 되었음을 알았다.

• 식물조직배양학회지
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• 제25권6호
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• pp.495-500
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• 1998

인삼(Panax ginseng C. A. Meyer) 캘러스로부터 분리한 원형질체를 배양하면서 배양시간에 따른 원형질체의 미세구조 변화와 원형질막 표면을 전자현미경으로 조사하였다. 3일 동안 배양된 원형질체에서는 조면소포체, 리보좀, 골기체, 미토콘드리아, 전색소체 등의 세포기관들의 수가 증가하였고 미소관도 관찰되었다. 골기체 주변에는 많은 골기소낭들이 형성되어 세포질 전반에 존재하였고, 이들 소낭들은 원형질막 바깥으로 돌출되어 돌기를 형성하기도 하였다. 소포체에서 유래된 액포속에는 액포의 함입에 의하여 골기소낭들이 들어 있는데, 이들 액포들은 융합에 의한 exocytosis로 원형질막 근처로 이동하여 원형질막과 융합한 다음, 세포벽 물질을 원형질막 바깥으로 방출하여 원형질막에 침적하였다. 전색소체는 많은 전분립을 함유하고 있었고, 미소관들은 원형질막 근처에서 막과 평형으로 배열하고 있었다. 배양된 원형질체의 표면에는 섬유소로 구성되어 있는 원섬유들이 서로 연결되어 있는 것이 관찰되었다.

• 식물조직배양학회지
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• 제27권6호
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• pp.429-434
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• 2000

인삼 (Panax ginseng C. A. Meyer) 캘러스 조직으로부터 분리한 원형질체를 DMSO가 O％에서 8％까지 여러 가지 농도로 첨가된 원형질체 배양배지 (1 mg/L 2,4-D, 4 mg/L NAA, 1 mg/L BAP, 0.4 M mannitol 및 0.8% agar가 첨가된 MS배지)에서 배양하였다. DMSO가 첨가되지 않은 배지에서 배양된 원형질체의 세포벽 재생률은 약 62%이고 세포분열빈도는 약 7％이었다. 반면에, 1% DMSO가 첨가된 배지에서 배양된 원형질체의 세포벽 재생률과 세포분열빈도는 각각 약 83%와 약 27%로 높게 나타났다. 그러나 배양된 원형질체의 세포활성은 배지에 첨가된 DMSO의 유무나 농도와는 관계없이 모든 배지에서 83∼88%로 차이를 보이지 않았다. 1% DMSO가 첨가된 배지에서 3일 동안 배양된 원형질체를 투과전자현미경으로 관찰하면 원형질막 근처에 평행으로 배열하고 있는 미소관들이 관찰되었다. 또한 원형질막 표면에는 세포벽 성분인 cellulose fibril들이 연결되어 다발을 형성하고 있는 것이 주사전자현미경으로 관찰되었다. DMSO가 첨가되지 않은 배지에서 배양된 원형질체에서는 이러한 전자현미경적 구조들이 관찰되지 않았다. 원형질체 배양배지에 첨가된 DMSO는 미소관편제센타 (MTOC)의 형성에 의하여 세포벽 재생과 세포분열을 유도하는 것으로 생각된다.

• Asian-Australasian Journal of Animal Sciences
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• 제15권8호
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• pp.1204-1209
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• 2002

Polymerization of heated or unheated pig skin collagen using microbial transglutaminase (MTGase) was investigated. Pig skin collagen samples were heated or left unheated, then enzymatically polymerized with MTGase. SDS-PAGE was conducted to confirm the intermolecular polymer and the results showed similar bands between samples without MTGase and unheated samples with MTGase. The polymerized product of pig skin collagen was not formed in unheated samples, even when MTGase was added during incubation. Different results were obtained from samples heated at $80^{\circ}C$ and $100^{\circ}C$ for 2 min, whereas the SDS-PAGE pattern indicated that a polymer band was generated in both cases. The heat treatment successfully modified the native structure of collagen and also made collagen more reactable in the MTGase polymerization system. Scanning Electron Microscope (SEM) investigation of pig skin collagen showed a biopolymer structure through intermolecular collagen crosslinking, while there were no intermolecular crosslinks in samples not treated with MTGase. There were no significant differences in fibril diameter between treated samples and controls. These results suggest that heat treatment of native pig skin collagen enhanced the polymerization capability of MTGase.

• 한국의류학회지
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• 제32권7호
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• pp.1095-1103
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• 2008

The effects of resin finish and dyeabilities of four kinds of Iyocell fabrics that were manufactured by four kinds of pulps were investigated. The dyeabilities of Iyocell fabrics were similar, but differed from cotton fabric. In early stage of 30 minutes, cotton fabric was shown higher dye exhaustion ratio than Iyocell fabrics, however after then cotton fabric did not increase dye exhaustion, Iyocell fabrics increased continuously. At last, the dye exhaustion ratio of Iyocell fabrics were about 75% and that of cotton fabric was 65%. Two kinds of experimental procedures were applied for Iyocell fabrics. One was what the fabrics were treated with resins and washed with cellulase, and then dyed with reactive dyes. The other procedure was the fabrics were dyed with reactive dyes, and then applied the resin treatments and cellulase washing. After fibrillation and washing the undyed Iyocell fabric and the Iyocell fabric that was dyed with C.I.Reactive Red 120, their weight loss ratios were 3.5% and 2.8%, respectively. Dyeing with reactive dyes caused the crosslinking between cellulose and dyes and the crosslinking decreased fibrillation. The weight loss by enzyme washing of Iyocell fabrics decreased by the glyoxal and melamine resin treatments. The reduction of weight loss can be caused by fibrillation decrease. Dyeing and resin treating can be showed the synergic effect on the reduction of fibrillation. The effect of glyoxal resin on the reduction of fibrillation was a little better than that of melamine resin.

• Molecules and Cells
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• 제23권2호
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• pp.228-238
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• 2007

Since molecular structure of hnRNP is not available in foreseeable future, it is best to construct a working model for hnRNP structure. A geometric problem, assembly of $700{\pm}20$ nucleotides with 48 proteins, is visualized by a frame work in which all the proteins participate in primary binding, followed by secondary, tertiary and quaternary binding with neighboring proteins without additional import. Thus, 40S hnRNP contains crown-like secondary structure (48 stemloops) and appearance of 6 petal (octamers) rose-like architectures. The proteins are wrapped by RNA. Co-transcriptional folding for RNP fibril of FMR1 gene can produce 2,571 stem-loops with frequency of 1 stem-loop/15.3 nucleotides and 53 40S hnRNP beaded structure. By spliceosome driven reactions, there occurs removal of 16 separate lariated RNPs, joining 17 separate beaded exonic structures and anchoring EJC on each exon junction. Skipping exon 12 has 5'GU, 3'AG and very compact folding pattern with frequency of 1 stem-loop per 12 nucleotides in short exon length (63 nucleotides). 5' end of exon 12 contains SS (Splicing Silencer) element of UAGGU. In exons 10, 15 and 17 where both regular and alternative splice sites exist, SS (hnRNP A1 binding site) is observed at the regular splicing site. End products are mature FMR-1 mRNP, 4 species of Pri-microRNAs derived from introns 7,9,15 and 3'UTR of exon17, respectively. There may also be some other regulatory RNAs containing ALU/Line elements as well.

• 공업화학
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• 제17권3호
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• pp.310-316
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• 2006

본 연구에서는 수중 악취의 원인 물질인 용존 암모니아를 제거하기 위해 분말형태의 활성탄을 사용하였다. 특히, 일반적인 분말활성탄은 암모니아 흡착능이 좋지 않기 때문에 흡착능을 높이기 위해 분말활성탄의 표면을 산 용액으로 함침시킨 산 첨착활성탄을 제조하였다. 이렇게 제조한 산 첨착활성탄을 섬유 재질로 된 다공성 지지막($10{\sim}50{\mu}m$)의 표면에 압력에 의한 분리 활성 여과 층을 형성시켜 흡착과 분리를 동시에 할 수 있는 혼합 공정을 구성하였다. 그 결과 혼합공정에서 암모니아 제거율이 60% 이상 되어, 일반 분말활성탄에 비해 10~15% 더 높은 흡착능을 보였다. 그리고 층이 형성된 동적막의 순수투과성능 실험을 보면 수투과도는 400~700 LMH로 정밀여과(Microfiltration)막 수준의 역할을 한다. 이는 수처리에서 기존의 분리막 공정보다 고효율적인 처리 유량을 유지하는 효과가 기대된다.

• EDISON SW 활용 경진대회 논문집
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• 제3회(2014년)
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• pp.237-249
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• 2014

Deposition of amyloid-${\beta}$ ($A{\beta}$) proteins is the conventional pathological hallmark of Alzheimer's disease (AD). The $A{\beta}$ protein formed from the amyloid precursor protein is predominated by the 40 residue protein ($A{\beta}40$) and by the 42 residue protein ($A{\beta}42$). While $A{\beta}40$ and $A{\beta}42$ differ in only two amino acid residues at the C-terminal end, $A{\beta}42$ is much more prone to aggregate and exhibits more neurotoxicity than $A{\beta}40$. Here, we investigate the molecular origin of the difference in the aggregation propensity of these two proteins by performing fully atomistic, explicit-water molecular dynamics simulations. Then, it is followed by the solvation thermodynamic analysis based on the integral-equation theory of liquids. We find that $A{\beta}42$ displays higher tendency to adopt ${\beta}$-sheet conformations than $A{\beta}40$, which would consequently facilitate the conversion to the ${\beta}$-sheet rich fibril structure. Furthermore, the solvation thermodynamic analysis on the simulated protein conformations indicates that $A{\beta}42$ is more hydrophobic than $A{\beta}40$, implying that the surrounding water imparts a larger thermodynamic driving force for the self-assembly of $A{\beta}42$. Taken together, our results provide structural and thermodynamic grounds on why $A{\beta}42$ is more aggregation-prone than $A{\beta}40$ in aqueous environments.

• EDISON SW 활용 경진대회 논문집
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• 제4회(2015년)
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• pp.14-23
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• 2015

Alzheimer's disease is one of the most common types of degenerative dementia. As a considerable cause of Alzheimer's disease, neurotoxic plaques composed of 39 to 42 residue-long amyloid beta($A{\beta}$) fibrils have been found in the patient's brain in large quantity. A previous study found that erythrosine B (ER), a red color food dye approved by FDA, inhibits the formation of amyloid beta fibril structures. Here, in an attempt to elucidate the inhibition mechanism, we performed molecular dynamics simulations to demonstrate the conformational change of $A{\beta}40$ induced by 2 ERs in atomistic detail. During the simulation, the ERs bound to the surfaces of both N-terminus and C-terminus regions of $A{\beta}40$ rapidly. The observed stacking of the ERs and the aromatic side chains near the N-terminus region suggests a possible inhibition mechanism in which disturbing the inter-chain stacking of PHEs destabilizes beta-sheet enriched in amyloid beta fibrils. The bound ERs block water molecules and thereby help stabilizing alpha helical structure at the main chain of C-terminus and interrupt the formation of the salt-bridge ASP23-LYS28 at the same time. Our findings can help better understanding of the current and upcoming treatment studies for Alzheimer's disease by suggesting inhibition mechanism of ER on the conformational transition of $A{\beta}40$ at the molecular level.