• Bulletin of the Korean Chemical Society
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• 제25권12호
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• pp.1791-1800
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• 2004

Angiotensin I, a model decapeptide, was glycosylated and partially hydrolyzed with HCl (6 N, 80 $^{\circ}C$, 4 h), aminopeptidase, and carboxypeptidase Y. A single peptide mass map obtained from truncated peptides in the partial acid hydrolysate of angiotensin and its glycosylation product mixture by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry enabled sequencing of angiotensin by a combinatorial procedure. MALDI-TOF and electrospray ionization (ESI) tandem mass spectrometric results indicate that both the N-terminal amino group of aspartic acid and the guanidinium group of the second residue arginine are glycosylated.

• Bulletin of the Korean Chemical Society
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• 제21권9호
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• pp.849-854
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• 2000

The protonation and divalent cation complexation equilibria of several quinolone antibiotics such as nalidixic acid (NAL),flumequine (FLU), oxolinic acid (OXO), ofloxacin (OFL), norfloxacin (NOR) and enoxacin (ENO) have been examined by potentiome tric titration and spectrophotometric method. The antibacterial activity of these drugs depends upon the pH and the concentration of metal cations such as Mg2+ , Ca2+ in solu-tion. The apparent ionization constants of NAL, FLU, OXO, OFL, NOR and ENO in aqueous solution were found to be 6.33, 6.51, 6.72, 7.18, 7.26, and 7.53, respectively. In aqueous solution, NAL, FLU and OXO were found to be present mainly as two chemical species : molecularand anionic; but OFL, NOR and ENO were present mainly as three chemical species : anionic, neutral zwitterionic and cationic form, in equilibrium. The pKa1 and pKa2are found to be 6.10 and 8.28 for OFL; 6.23 and 8.55 for NOR; 6.32 and8.62 for ENO, respec-tively. The complex formation constants between OFL, NOR or FLU and some divalent cations are measured at pH 7.5. The 1 : 1 complexes are formed mainly by ion-dipole interaction. FLU has somewhat larger Kf values than OFL and NOR because its molecular size is small and the FLU is present asanionic form at pH 7.5.

• Molecules and Cells
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• 제28권3호
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• pp.175-181
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• 2009

In hypertriglyceridaemic individuals, atherosclerogenesis is associated with the increased concentrations of very low density lipoprotein (VLDL) and VLDL-associated remnant particles. In vitro studies have suggested that VLDL induces foam cells formation. To reveal the changes of the proteins expression in the process of foam cells formation induced by VLDL, we performed a proteomic analysis of the foam cells based on the stimulation of differentiated THP-1 cells with VLDL. Using two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis, 14 differentially expressed proteins, containing 8 up-regulated proteins and 6 down-regulated proteins were identified. The proteins are involved in energy metabolism, oxidative stress, cell growth, differentiation and apoptosis, such as adipose differentiation-related protein (ADRP), enolase, S100A11, heat shock protein 27 and so on. In addition, the expression of some selected proteins was confirmed by Western blot and RT-PCR analysis. The results suggest that VLDL not only induces lipid accumulation, but also brings about foam cells diverse characteristics by altering the expression of various proteins.

• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.275-280
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• 2010

Actinobacillus actinomycetemcomitans is a gram-negative, nonmotile coccobacillus bacterium that is associated with several human diseases, including endocarditis, meningitis, osteomyelitis, subcutaneous abscesses and periodontal diseases. A full-length Omp1-like protein gene from A. actinomycetemcomitans was cloned into a pQE30 vector and overexpressed in Escherichia coli BL21(DE3) cells. The protein revealed sequence homologies to Seventeen kilodalton proteins (Skp) from Pasteurella multocida and E. coli that have been characterized as periplasmic chaperones. This soluble Omp1-like protein was successfully purified to homogeneity for further folding and functional studies. The purity, identity, and conformation of the protein were determined using sodium dodecyl sulfate polyacrylamide gel electrophoresis, matrix-assisted laser desorption ionization mass spectrometry, circular dichroism, fluorescence spectroscopic, and differential scanning calorimetric studies. We showed that the protein formed an oligomer larger than a tetramer. We found, further, that it is comprised of mostly $\alpha$-helices and boasts high thermal stability.

• Mass Spectrometry Letters
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• 제9권3호
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• pp.81-85
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• 2018

In this study, the chemical composition of bacterial melanin isolated from the Streptomyces glaucescens strain was elucidated by ultra-high-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Ultra-high-resolution mass profiles of the microbial melanin product were acquired using a 15 Tesla FT-ICR mass spectrometer in positive and negative ion modes via electrospray ionization to obtain more complete descriptions of the molecular compositions of melanin-derived organic constituents. A mass resolving power of 500,000 (at m/z 400) was achieved for all spectra while collecting 400 scans per sample with a 4 M transient. The results of this analysis revealed that the melanin pigment isolated from S. glaucescens predominantly exhibits CHON and CHO species, which belong to the proteins class of compounds, with the mean C/O and C/N ratios of 4.3 and 13.1, thus suggesting that the melanin could be eumelanin. This analytical approach could be utilized to investigate the molecular compositions of a variety of natural or synthetic melanins. The compositional features of melanins are important for understanding their formation mechanisms and physico-chemical properties.

• 전자공학회논문지SC
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• 제48권3호
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• pp.53-59
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• 2011

본 논문에서는 DNA 올리고뉴클리오타이드(oligonucleotide)를 통한 전하 이동을 기반으로 하는 분자성 전자광학 스위칭 소자를 제시한다. DNA 올리고머(oligomer)가 흡착되어 있는 금전극에 전자들이 주입되어 전극으로부터 DNA 올리고머로 전하가 흘러가게 하고 이 전하의 이동도를 광학적 스위칭으로 확인할 수 있도록 제안되었다. DNA 올리고머의 흡착량이 증가함에 따라 DNA를 통한 전하의 이동성과 전극 표면에서의 전하전달 제한성으로 인해 전리전류는 감소하였다. DNA의 끝단에 합성된 Cy3 형광 분자의 점멸도를 전극 기반의 전하 주입법을 이용하여 확인하였다. 이러한 결과들은 DNA 올리고머를 이용한 새로운 분자성 전자광학 스위칭 소자에 이용될 수 있다.

• 한국축산식품학회지
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• 제43권1호
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• pp.184-194
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• 2023

Recently, interest in food-derived bioactive peptides as promising ingredients for the prevention and improvement of hypertension is increasing. The purpose of this study was to determine the structure and antihypertensive effect of an antioxidant peptide purified from velvet antler in a previous study and evaluate its potential as a various bioactive peptide. Molecular weight (MW) and amino acid sequences of the purified peptide were determined by quadrupole time-of-flight electrospray ionization mass spectroscopy. The angiotensin I-converting enzyme (ACE) inhibition activity of the purified peptide was assessed by enzyme reaction methods and in silico molecular docking analysis to determine the interaction between the purified peptide and ACE. Also, antihypertensive effect of the purified peptide in spontaneously hypertensive rats (SHRs) was investigated. The purified antioxidant peptide was identified to be a pentapeptide Asp-Asn-Arg-Tyr-Tyr with a MW of 730.31 Da. This pentapeptide showed potent inhibition activity against ACE (IC₅₀ value, 3.72 μM). Molecular docking studies revealed a good and stable binding affinity between purified peptide and ACE and indicated that the purified peptide could interact with HOH2570, ARG522, ARG124, GLU143, HIS387, TRP357, and GLU403 residues of ACE. Furthermore, oral administration of the pentapeptide significantly reduced blood pressure in SHRs. The pentapeptide derived from enzymatic hydrolysate of velvet antler is an excellent ACE inhibitor. It might be effectively applied as an animal-based functional food ingredient.

• Journal of Microbiology and Biotechnology
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• 제14권3호
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• pp.620-627
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• 2004

On the foundation of a database of genome sequences and protein analyses, the ability to clone a gene based on a peptide analysis is becoming more feasible and effective for identifying a specific gene and its protein product of interest. As such, the current study conducted a protein analysis using 2-D PAGE followed by MALDI- TOF and ESI-MS to identify a highly expressed gene product of C. parasitica. A distinctive and highly expressed protein spot with a molecular size of 47.2 kDa was randomly selected and MALDI-TOF MS analysis was conducted. A homology search indicated that the protein appeared to be a fungal enolase (enol). Meanwhile, multiple alignments of fungal enolases revealed a conserved amino acid sequence, from which degenerated primers were designed. A screening of the genomic $\lambda$ library of C. parasitica, using the PCR amplicon as a probe, was conducted to obtain the full-length gene, while RT-PCR was performed for the cDNA. The E. coli-expressed eno 1 exhibited enolase enzymatic activity, indicating that the cloned gene encoded the C. parasitica enolase. Moreover, ESI-MS of two of the separated peptides resolved from the protein spot on 2-D PAGE revealed sequences identical to the deduced sequences, suggesting that the cloned gene indeed encoded the resolved protein spot. Northern blot analysis indicated a consistent accumulation of an eno1 transcript during the cultivation.

• 한국군사과학기술학회지
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• 제14권1호
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• pp.147-153
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• 2011

A series of nonequilibrium molecular dynamics(NEMD) simulations are performed to investigate the kinetic energy and velocity distributions of molecules in shock waves. In the simulations, argon molecules are used as a medium gas through which shock waves are propagating. The kinetic energy distribution profiles reveals that as a strong shock wave whose Mach number is 27.1 is applied, 39.6% of argon molecules inside the shock wave have larger kinetic energy than molecular ionization energy. This indicates that an application of a strong shock wave to argon gas can give rise to an intense light. The velocity distribution profiles in z direction along which shock waves propagate clearly represent two Maxwell-Boltzmann distributions of molecular velocities in two equilibrium regions and one bimodal velocity distribution profile that is attributed to a nonequilibrium region. The peak appearing in the directional temperature in z direction is discussed on a basis of the bimodal velocity distribution in the nonequilibrium region.

• 한국식품영양과학회지
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• 제18권2호
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• pp.205-210
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• 1989

Capillary column GLC 및 GCMS를 병용하는 분석방법을 이용하여 식물유 트리글리세리드 분자종과 산화안정성과의 관계를 밝히기 위해서, 규산 컬럼으로 분획한 대두유 트리글리세리드를 모델 시료로 하여 $60^{\circ}C$, 암소에서 저장하면서 산화에 따른 트리글리세리드 각 분자종의 산화안정성을 조사하였다. 대두유 트리글리세리드의 주요 분자종은 LLL(19.6%), OLL(17.4%), PLL(14.2%), OLO(10.2%) 및 PLO(9.4%)이었으며, 트리글리세리드 분자종의 산화안정성은 전반적으로 구성불포차지방산의 이중결합수가 적을 수록 증가하는 경향을 보였다. 그런데 트리글리세리드를 구성하는 불포화지방산들의 이중결합수가 같을 경우는 불포화도가 낮은 지방산이 결합되어 있는 분자종의 산화안정성이 높았고, 또 결합되어 있는 불포화지방산의 이중결합수 및 불포화도가 똑같은 경우에는 공존하고 있는 포화지방산의 acyl의 사슬길이가 짧은 분자종의 산화안정성이 높은 것으로 밝혀져, 식물유 트리글리세리드 분자종의 산화안정성에는 구성불포화지방산의 이중결합수와 불포화도 및 공존하고 있는 포화지방산의 acyl기의 사슬길이가 중요한 영향을 미치는 인자임을 알 수 있었다.