• Smart Structures and Systems
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• 제8권1호
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• pp.17-37
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• 2011

The microcantilever (MCL) sensor is one of the most promising platforms for next-generation label-free biosensing applications. It outperforms conventional label-free detection methods in terms of portability and parallelization. In this paper, an overview of recent advances in our understanding of the coupling between biomolecular interactions and MCL responses is given. A dual compact optical MCL sensing platform was built to enable biosensing experiments both in gas-phase environments and in solutions. The thermal bimorph effect was found to be an effective nanomanipulator for the MCL platform calibration. The study of the alkanethiol self-assembly monolayer (SAM) chain length effect revealed that 1-octanethiol ($C_8H_{17}SH$) induced a larger deflection than that from 1-dodecanethiol ($C_{12}H_{25}SH$) in solutions. Using the clinically relevant biomarker C-reactive protein (CRP), we revealed that the analytical sensitivity of the MCL reached a diagnostic level of $1{\sim}500{\mu}g/ml$ within a 7% coefficient of variation. Using grazing incident x-ray diffractometer (GIXRD) analysis, we found that the gold surface was dominated by the (111) crystalline plane. Moreover, using X-ray photoelectron spectroscopy (XPS) analysis, we confirmed that the Au-S covalent bonds occurred in SAM adsorption whereas CRP molecular bindings occurred in protein analysis. First principles density functional theory (DFT) simulations were also used to examine biomolecular adsorption mechanisms. Multiscale modeling was then developed to connect the interactions at the molecular level with the MCL mechanical response. The alkanethiol SAM chain length effect in air was successfully predicted using the multiscale scheme.

• Journal of Microbiology and Biotechnology
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• 제25권11호
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• pp.1894-1901
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• 2015

A novel sulfatase gene, ary423 (1,536 bp ORF), encoding a protein of 511 amino acids with a calculated molecular mass of 56 kDa, was identified from Flammeovirga pacifica, which was isolated from deep-sea sediments of west Pacific Ocean. Amino acid sequence analysis revealed that Ary423 possessed a conserved C-X-A-X-R motif, which was recognized as the sulfatase signature. Phylogenetic analysis suggested that Ary423 belonged to arylsulfatases. After heterologous expression in Escherichia coli cells, the recombinant Ary423 was purified with a Ni⁺ affinity column, and was shown to be highly active at a broad range of temperatures from 30° to 70℃, with maximum activity at 40℃. Furthermore, recombinant Ary423 retained more than 70% and 40% of its maximum activity after 12 h of incubation at 50℃ and 60℃, respectively, exhibiting good thermostability at high temperatures. The optimal pH for Ary423 was determined to be 8.0 and the activity of Ary423 could be slightly enhanced by Mg²⁺. The recombinant enzyme could hydrolyze sulfate ester bonds in p-nitrophenyl sulfate (NPS) and Asparagus crude polysaccharides with a specific activity of 64.8 U/mg and 25.4 U/mg, respectively. These favorable properties could make Ary423 attractive for application in the desulfating process of agar production.

• Journal of Microbiology and Biotechnology
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• 제28권9호
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• pp.1482-1492
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• 2018

Fusarium oxysporum trypsin (FOT) is a fungal serine protease similar to mammal trypsin. The FOT could be successfully expressed in Pichiapastoris by engineering the natural propeptide APQEIPN. In this study, we constructed two recombinant enzymes with engineered amino acid sequences added to the N-terminus of FOT and expressed in P. pastoris. The N-terminal residues had various effects on the structural and functional properties of trypsin. The FOT, and the recombinants TE (with peptide YVEF) and TS (with peptide YV) displayed the same optimum temperature ($40^{\circ}C$) and pH (8.0). However, the combinants TE and TS showed significantly increased thermal stability at $40^{\circ}C$ and $50^{\circ}C$. Moreover, the combinants TE and TS also showed enhanced tolerance of alkaline pH conditions. Compared with those of wild-type FOT, the intramolecular hydrogen bonds and the cation ${\pi}$-interactions of the recombinants TE and TS were significantly increased. The recombinants TE and TS also had significantly increased catalytic efficiencies (referring to the specificity constant, $k_{cat}/K_m$), 1.75-fold and 1.23-fold than wild-type FOT. In silico modeling analysis uncovered that the introduction of the peptides YVEF and YV resulted in shorter distances between the substrate binding pocket (D174, G198, and G208) and catalytic triad (His42, Asp102, and Ser180), which would improve the electron transfer rate and catalytic efficiency. In addition, N-terminal residues modification described here may be a useful approach for improving the catalytic efficiencies and characteristics of other target enzymes.

• 한국광학회지
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• 제9권3호
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• pp.162-167
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• 1998

CF4 이온빔보조증착법으로 굴절률이 유리보다 낮은 SiOxFy 박막을 제작하고 광학적, 구조적 및 화학적 특성을 연구하였다. End-Hall 이온총의 양극전압의 간소에 따라 SiOxFy 박막의 굴절률은 1.455까지 변하였으며, 이온빔 전류밀도의 증가에 따라서 굴절률은 1.462에서 1.430까지 변하였다. XPS와 FT-IR 분석으로부터 SiOxFy 박막의 F양이 증가함에 따라 Si-O 결합은 파수가 높은 쪽으로 이동하였고, F이 약 8.5at.%인 SiOxFy 박막은 OH 결합이 매우 감소하였으여, 박막 표면의 F이 H2O와 결합하여 탈착되는 것을 알았다. SiOxFy 박막의 응력은 0.3GPa 이하의 압축응력이었으며, 결정구조는 비정질이었다. SiOxFy 박막의 응용으로서 SiOxFy 박막과 흡수층 Si 박막을 이용하여 2층 반사방지막을 제작하였다.

• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3749-3754
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• 2013

Two 3D isomorphous and isostructural complexes, namely, $[Zn(BDOA)(bpy)(H_2O)_2]_n$ (1) and $[Cd(BDOA)-(bpy)(H_2O)_2]_n$ (2); (BDOA = Benzene-1,4-dioxyacetic acid, bpy = 4,4'-bipyridine) were synthesized under hydrothermal conditions and characterized by means of elemental analyses, thermogravimetric (TG), infrared spectrometry, and single crystal X-ray diffraction. Complexes 1 and 2 crystallize in the triclinic system, space group P-1 and each metal ion in the complexes are six-coordinated with the same coordination environment. In the as-synthesized complexes, $BDOA^{2-}$ anions link central metal ions to form a 1D zigzag chain $[-BDOA^{2-}-Zn(Cd)-BDOA^{2-}-Zn(Cd)-]_{\infty}$, whereas bpy pillars connect metal ions to generate a 1D linear chain $[-bpy-Zn(Cd)-bpy-Zn(Cd)-]_{\infty}$. Both infinite chains are interweaved into 2D grid-like layers which are further constructed into a 3D open framework, where hydrogen bonds play as the bridges between the adjacent 2D layers. Luminescent properties of complex 1 showed selectivity for $Hg^{2+}$ ion.

• Korean Chemical Engineering Research
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• 제50권6호
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• pp.1064-1067
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• 2012

최근 저가의 풍부한 재생 가능 천연자원인 식물성 오일에 대한 관심이 증가되고 있다. 식물성 오일은 친환경적인 생분해성 고분자 물질들의 원료로서 사용될 수 있다. 본 연구에서는 acrylated epoxidized soybean oil (AESO)과 2-aminoethanol의 중합 반응에 의해 poly(${\beta}$-amino ester)를 합성하였다. AESO와 2-aminoethanol의 몰비를 변화시켜 다양한 비율의 고분자 필름을 제조하였다. FT-IR을 이용하여 poly(${\beta}$-amino ester) 내의 C-N 결합의 생성을 확인하였으며, 98% 이상의 겔함량으로부터 가교 고분자 네트웍이 합성되었음을 확인하였다. 고분자 필름의 인장강도와 신장률은 각각 0.3~1.3 MPa, 32~55%였다. 고분자 필름은 lipase 효소가 첨가된 pH 7.2 완충용액에서 35일 경과 후 2~7%의 질량감소를 보였다.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2001년도 추계학술대회 및 정기총회
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• pp.94-94
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• 2001

Prostaglandin endoperoxide H synthase (PGHS) catalyzes the committed step in prostaglandins and thromboxane A$_2$-- oxygenation of arachidonic acid to the hydroperoxy endoperoxide PGG$_2$, followed by reduction PGG$_2$to the alcohol PGH$_2$. The two reactions by PGHS -- cyclooxygenase and peroxidase -- occur at distinct but structurally and functionally interconnected sites. The peroxidase reaction occurs at a heme-containing active site located near the protein surface. The cyclooxygenase reaction occurs in a hydrophobic channel in the core of the enzyme. Initially a peroxide reacts with the heme group, yielding Compound I and an alcohol derived from the oxidizing peroxide. Compound I next undergoes an intramolecular reduction by a single electron traveling from Tyr385 along the peptide chain to the proximal heme ligand, His388, and finally to the heme group. Following the binding of arachidonic acid, Tyr385 tyrosyl radical initiates the cyclooxygenase reaction by abstracting the 13-pro(5) hydrogen atom to give an arachidonyl radical, which sequentially reacts with two molecules of oxygen to yield PGG$_2$. In order to characterize PGHS peroxidase active site, we examined various lipid peroxides with purified recombinant ovine PGHS proteins and determined the rate constants. The results have shown that twenty-carbon unsaturated fatty acid hydroperoxides have similar efficiency in peroxidation by PGHS, irrespective of either the location of hydroperoxy group or the number of double bonds. It was also confirmed by the subsequent study with PGHS peroxidase active site mutants.

• Asian Pacific Journal of Cancer Prevention
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• 제16권9호
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• pp.3817-3825
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• 2015

Background: The human protein methyl-transferase DOT1L catalyzes the methylation of histone H3 on lysine 79 (H3K79) at homeobox genes and is also involved in a number of significant processes ranging from gene expression to DNA-damage response and cell cycle progression. Inhibition of DOT1L activity by shRNA or small-molecule inhibitors has been established to prevent proliferation of various MLL-rearranged leukemia cells in vitro, establishing DOT1L an attractive therapeutic target for mixed lineage leukemia (MLL). Most of the drugs currently in use for the MLL treatment are reported to have low efficacy, hence this study focused on various natural compounds which exhibit minimal toxic effects and high efficacy for the target receptor. Materials and Methods: Structures of human protein methyl-transferase DOT1L and natural compound databases were downloaded from various sources. Virtual screening, molecular docking, dynamics simulation and drug likeness studies were performed for those natural compounds to evaluate and analyze their anti-cancer activity. Results: The top five screened compounds possessing good binding affinity were identified as potential high affinity inhibitors against DOT1L's active site. The top ranking molecule amongst the screened ligands had a Glide g-score of -10.940 kcal/mol and Glide e-model score of -86.011 with 5 hydrogen bonds and 12 hydrophobic contacts. This ligand's behaviour also showed consistency during the simulation of protein-ligand complex for 20000 ps, which is indicative of its stability in the receptor pocket. Conclusions: The ligand obtained out of this screening study can be considered as a potential inhibitor for DOT1L and further can be treated as a lead for the drug designing pipeline.

• Bulletin of the Korean Chemical Society
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• 제26권2호
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• pp.253-259
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• 2005

[$(tacn)_4Fe_4O_2(OH)_4]_2{\cdot}8Br{\cdot}9H_2O$ (tacn = 1,4,7-triazacyclononane), a tetranuclear iron(III) complex was synthesized by the hydrolysis of (tacn)FeCl3 and crystallizes in the orthorhombic space group, Pca2(1), with cell parameters, a = 37.574(3) $\AA$, b = 16.9245(12) $\AA$, c = 14.2830(11) $\AA$, V = 9082.9(12) ${\AA}^3$. [$(tacn)_4Fe_4O_2(OH)_4]^{4+}$ cations approach S4 point symmetry containing an adamantane skeleton. Four Fe(III) atoms have distorted octahedral environments with two hydroxo and an oxo bridges. Two [$(tacn)_4Fe_4O_2(OH)_4]^{4+}$ clusters having different Fe…Fe distances are connected to each other by the networked hydrogen bonds. The electrochemical behavior reveals irreversible three cathodic and two anodic peaks. Magnetic properties are characterized by antiferromagnetic (AF) interactions between Fe(III) ion spins. However, the low-lying states are still magnetic and exhibit a blocking behavior and a magnetic hysteresis at low temperatures.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2002년도 생물공학의 동향 (X)
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• pp.91-94
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• 2002

Arachidonic acid is a polyunsaturated fatty acid(PUFA) containing twenty carbon atoms with four double bonds. The family of w-6 PUFA, including arachidonic acid as well as r-linoleic acid, was served as intermediates in the formation of several key prostaglandin and leukotrienes. Several fungal strains of the genus Mortierella accumulate high amounts of arachidonic acid. In this study experiments were carried out to optimize the culture conditions for the mass production of fungus Mortierella alpina DSA -12 and lipid production with high proportion of polyunsaturated fatty acids, especially arachidonic acid. The batch culture was carried out in 500 L fermenter containing 50 g/L glucose, 18 g/L corn-steep powder and 100 mg/L MnS04 under $25^{\circ}C$, aeration rate of 0.5 vvm and agitation speed of 200 rpm without pH control. As a result, we could be obtained 22 g/L of cell mass with high contents of lipid 12.1 g/L) and arachidonic acid (5.1 g/L) The intermittent fed-batch culture was performed in the medium containing 20 g/L glucose and 10 g/L corn-steep powder. The final glucose concentration was 170 g/L and pH was maintained at 5.5 ${\sim}$ 6.0 by adding 14% ammonia solution. It was shown relatively high cell concentration (70.5 g/L) with high contents of lipid (45.8 g/L) and arachidonic acid 08.3 g/L). Therefore, when compared to batch cultures, the high concentration of arachidonic acid could be obtained by fed-batch culture using M. alpina DSA -12. These results imply that the fed-batch culture of M. alpina DSA -12 was feasible in industrial purpose and could be employed in the commercial production of arachidonic acid.