• Molecules and Cells
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• 제24권2호
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• pp.268-275
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• 2007

Protein phosphorylation plays a key role in signal transduction in cells. Since phosphoproteins are present in low abundance, enrichment methods are required for their purification and analysis. Chemical derivatization strategies have been devised for enriching phosphoproteins and phosphopeptides. In this report, we employed a strategy that replaces the phosphate moieties on serine and threonine residues with a biotin-containing tag via a series of chemical reactions. Ribulose 1,5-bisphosphate carboxylase/oxygenase (RUBISCO)-depleted protein extracts prepared from Arabidopsis seedlings were chemically modified for 'biotin-tagging'. The biotinylated (previously phosphorylated) proteins were then selectively isolated by avidin-biotin affinity chromatography, followed by two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). This led to the identification of 31 protein spots, representing 18 different proteins, which are implicated in a variety of cellular processes. Despite its current technical limitations, with further improvements in tools and techniques this strategy may be developed into a useful approach.

• Bulletin of the Korean Chemical Society
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• 제5권5호
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• pp.175-178
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• 1984

Two series of membranes have been prepared by postcrosslinking highly syndiotactic and isotactic poly (2-hydroxyethyl methacrylate), P(HEMA). The crosslinker used was hexamethylene diisocyante (HMDIC). The distribution coefficients (K$_{D2}$) of the model solutes such as urea (and thiourea), their derivatives, homologous alcohol series and amide sreies in water-swollen tactic P(HEMA) membranes at $25^{\circ}C$ were mesaured. In addition, the concentration effects of acetamide and butyramid were also measured. On the basis of hydrophobic interaction and the structural factors of tactic P(HEMA) membranes, the hydrophobic adsorption of the solutes in the polymer matrix were discussed. The results showed that the more hydrphobic the solute is, the higher the $K_{D2}$ value is. And the polymer conformation also affects the distribution of solvents.

• Composites Research
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• 제32권6호
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• pp.319-326
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• 2019

본 연구에서는 재활용이 가능하며 열가소성 특성을 지닌 신규 고분자 수지를 개발하고 합성하였다. 이렇게 개발된 수지와 판상형 질화붕소(h-BN) 사이의 계면 친화성이 좋음을 계산과학을 통하여 확인하고 열압기(hot press)를 이용하여 복합소재를 제조하였다. 고분자 수지와 필러 사이의 계면 친화성과 함께 복합소재 제조시 발생되는 전단력(shear force) 만으로도 매우 높은 필러 정렬도를 지닌 복합소재를 제조할 수 있었고, 이러한 이유로 복합소재는 최대 13.8 W/mK의 높은 열전도도를 갖는 것을 확인하였다. 또한, 개발된 수지가 화학적으로 분해 가능한 장점을 이용하여 제조된 복합소재로부터 물리/화학적 변성 없이 필러를 회수할 수 있었고 이렇게 회수된 필러는 향후 다양한 신규 복합소재 제조에 재활용이 가능하다.

• KSBB Journal
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• 제30권6호
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• pp.296-301
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• 2015

Eggshell-based biocomposites have become attractive due to their exquisite nanostructure and biological properties, which are mainly composed of highly organized calcium carbonate crystals controlled by organic macromolecules such as proteins and polysaccharides. Here, we designed the recombinant fusion protein of a putative eggshell matrix protein named as GG1234 and a fluorescent reporter protein of DsRed. The protein was successfully over-expressed in E. coli and purified by Ni-NTA affinity chromatography. In vitro calcium carbonate crystallization was conducted in the presence of the fusion protein, and morphological change was investigated. The protein inhibited the calcite growth in vitro, and spherical calcium carbonate micro-particles with the diameter of about $20-30{\mu}m$ were obtained. We expect that this study would be helpful for better understanding of eggshell-based biomineralization.

• 한국응용과학기술학회지
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• 제25권1호
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• pp.15-22
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• 2008

The effects of fillers on the mechanical and thermal properties of glass/novolac composites have been studied. The matrix polymer and reinforcement were novolac type phenolic resin and milled glass fiber, respectively. Three different fillers, such as calcium carbonate, aluminum oxide, and wood powder were used for glass fiber reinforced plastic(GFRP) manufacture. Gravity, moisture content, tensile and flexural strength were measured to analyze the mechanical properties of GFRP and the final composites was burned in the electronic furnace at $1000^{\circ}C$ to confirm thermal properties GFRP containing aluminium oxide shows the highest thermal stability with 32% of weight loss at $1000^{\circ}C$ for one hour. GFRP containing calcium carbonate shows the maximum flexural strength (146 MPa), but that containing wood powder dose the highest tensile strength (65 MPa). Conclusively, we found that the characteristics of final composites strongly depend on several factors, such as types of materials, contents and chemical affinity of fillers. Therefore, it is very important to set up the combination of fillers for GFRP manufacturing to improve both mechanical and thermal properties at the same time.

• BMB Reports
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• 제28권2호
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• pp.162-169
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• 1995

Rat brain succinic semialdehyde dehydrogenase (EC 1.2.1.24 SSADH) activity was detected in mitochondrial, cytosolic and microsomal fractions. Brain mitochondrial soluble SSADH was purified by ammonium sulfate precipitation, DEAE Sephacel, and 5'-AMP Sepharose 4B affinity chromatography. The purified enzyme was shown to consist of four identical subunits, and the molecular weight of a subunit was 55 kD. The $K_m$ for short chain aliphatic aldehydes and aromatic aldehydes were at the $10^{-3}M$ level but that for succinic semialdehyde was 2.2 ${\mu}M$. Either $NAD^+$ or $NADP^+$ can be used as a cofactor but the affinity for $NAD^+$ was 10 times higher than that for $NADP^+$. The brain cytosolic SSADH was also purified by ammonium sulfate precipitation, DEAE Sephacel, Blue Sepharose CL-6B and 5'-AMP Sepharose 4B affinity chromatography and its Km for short chain aliphatic aldehydes was at the $10^{-3}$ level but that for succinic semialdehyde was 3.3 ${\mu}M$. $NAD^+$ can be used as a cofactor for this enzyme. We suppose that both enzyme might participate in the oxidation of succinic semialdehyde, which is produced during GABA metabolism. The activity of both cytosolic and mitochondrial SSADH was markedly inhibited when the concentration of succinic semialdehyde was high. The reciprocal plot pattern of product inhibition and initial velocity indicated a sequential ordered mechanism for mitochondrial matrix SSADH. Chemical modification data suggested that amino acid residues such as cysteine, serine and lysine might participate in the SSADH reaction.

• 멤브레인
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• 제28권1호
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• pp.55-61
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• 2018

급진적인 산업발전에 따른 무분별한 이산화탄소 배출로 인하여 지구온난화, 이상 기후 등의 문제가 불거지고 있으며 이는 한 나라에만 국한되지 않은 국제적인 문제가 되었다. 위와 같은 문제를 해결하고자 본 연구에서는 이산화탄소에 대해 높은 친화도를 가지고 있는 PEGBEM-g-POEM 가지형 공중합체를 합성하였으며 $CaCO_3$염을 첨가하여 염의 중량에 따른 혼합매질분리막의 이산화탄소/질소 투과 성능을 관찰하였다. $CaCO_3$염이 고분자 중량 대비 50% 첨가되었을 때 최적의 이산화탄소/질소 분리 투과성능을 보였으며, 선택도는 염을 추가하기 전 44.7에서 45.42로 크게 변하지 않은 반면 이산화탄소 투과도는 염을 첨가하기 전 22.5 GPU에서 28.16 GPU로 약 25% 향상되었다. 이는 첨가한 염과 이산화탄소간의 상호작용으로 인하여 향상된 고분자 복합막의 이산화탄소에 대한 용해도에 기인하는 것으로 생각된다. 또한 염을 과량으로 첨가한 경우에는 고분자가 복합막의 표면을 충분히 메우지 못하여 계면결함이 생성되었으며 이로 인해 이산화탄소 기체 분리성능이 감소하였다. 기체분리성능 향상을 위해서는 적정량의 염 첨가가 필수적인 것으로 분석되었다.

• Elastomers and Composites
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• 제43권4호
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• pp.221-229
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• 2008

전분을 매트리스 고분자로 하여 아크릴 모노머인 2-ethylhexylacrylate와 methyl methacrylate, acrylic acid를 그래프트 중합하였다. 중합은 라디칼 유화중합에 의하여 전분의 함량을 증가시키면서 수행되었다. 효소인 $\alpha$-amylase 가 전분 대비 0.174% 투입되었을 때 가장 안정한 중합물이 얻어졌으며 전분의 함량이 증가함에 따라 중합물의 유리전이온도가 상승하였다. 전분 함량의 증가에 따라 계내의 -OH기가 많아짐에 따라 중합물의 입자 크기와 점도가 증가하였다. Peel strength는 전분 함량이 증가할수록 -OH기 증가에 의해 중합물이 피착체 표면과의 친화력 상승이 일어나서 증가하였다. 반면 초기 점착력은 전분 함량이 증가할수록 유리전이온도의 증가에 따라 필름의 경도가 증가하면서 감소하였다.

• 폴리머
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• 제39권1호
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• pp.136-143
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• 2015

초음파를 이용하여 poly(vinyl alcohol)(PVA)를 multiwalled carbon nanotube(MWCNT) 표면에 수상 그래프팅하였고, 개질된 MWCNT를 이용하여 PVA와 나노복합체를 제조하였다. PVA로 개질된 MWCNT는 PVA 매트리스에 높은 친화성을 띠고, 우수한 분산성을 가지며, 그 복합체는 균일한 물성을 가지고 있었다. 이로 인하여 0.1 wt% 함량의 MWCNT 첨가시에 전기전도도의 percolation threshold이 관찰되었다. 개질한 MWCNT를 3.0 wt%로 사용한 복합체는 순수 PVA 대비 인장강도는 약 50%, 파단 연신율은 약 430%, 모듈러스는 약 100% 증가하였다. 또한 개질된 MWCNT는 PVA 매트리스에 핵제로 작용하여 5.0 wt% 첨가 시, 결정화온도를 $8.5^{\circ}C$ 증가시키고 결정화도는 11.5% 증가하였다.

• 대한방사성의약품학회지
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• 제9권1호
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• pp.49-55
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• 2023

Tumors are encircled by various non-cancerous cell types in the extracellular matrix, including fibroblasts, endothelial cells, immune cells, and cytokines. Fibroblasts are the most critical cells in the tumor stroma and play an important role in tumor development, which has been highlighted in some epithelial cancers. Many studies have shown a tight connection between cancerous cells and fibroblasts in the last decade. Regulatory factors secreted into the tumor environment by special fibroblast cells, cancer-associated fibroblasts (CAFs), play an important role in tumor and vessel development, metastasis, and therapy resistance. This review addresses the development of FAP inhibitors, emphasizing the first, second, and latest generations. First-generation inhibitors exhibit low selectivity and chemical stability, encouraging researchers to develop new scaffolds based on preclinical and clinical data. Second-generation enzymes such as UAMC-1110 demonstrated enhanced FAP binding and better selectivity. Targeted treatment and diagnostic imaging have become possible by further developing radionuclide-labeled fibroblast activation protein inhibitors (FAPIs). Although all three FAPIs (01, 02, and 04) showed excellent preclinical and clinical findings. The final optimization of these FAPI scaffolds resulted in FAPI-46 with the highest tumor-to-background ratio and better binding affinity.