• Bulletin of the Korean Chemical Society
• /
• 제28권5호
• /
• pp.730-736
• /
• 2007

The interaction of a polyoxometal (POM), K6SiW11Co(H2O)O39.10H2O (K6) as a Keggin, with human serum albumin (HSA) was studied by different methods and techniques. Binding studies show two sets of binding sites for interaction of POM to HSA. Binding analysis and isothermal calorimetery revealed that, the first set of binding site has lower number of bound ligand per mole of protein (ν), lower Hill constant (n), higher binding constant (K), more negative entropy (ΔS) and more electrostatic interaction in comparison to the second set of binding site. In addition, differential scanning calorimetery (DSC) and spectrophotometery data showed that, there are two energetic domains. The first domain is less stable (lower Tm and Cp) which corresponds to the tail segment of HSA and another with more stability is related to the head segment of HSA. Polyoxometal also decreases the stability of protein as Tm, secondary and tertiary structure as well as quenching of the fluorescence decrease. On other hand, perturbations in tertiary structure are more than secondary structure.

• 미생물학회지
• /
• 제49권3호
• /
• pp.253-261
• /
• 2013

본 연구에서는 숙성된 된장으로부터 분리된 유산균에 의한 aflatoxin $B_1$의 결합 정도를 배양조건에 따라 측정하였고, 물리화학적 처리조건이 aflatoxin $B_1$에 대한 유산균 세포의 결합력에 미치는 영향을 살펴보았다. Enterococcus faecium DJ22, Lactobacillus fermentum DJ35, Lactobacillus rhamnosus DJ42 및 Lactobacillus pentosus DJ47는 19.3-52.1% 정도의 aflatoxin $B_1$ 결합 효과를 나타내어 균종에 따라 결합력에 차이가 있었다. 하지만 E. faecalis DJ14, Lactobacillus panis DJ29 및 Pediococcus halophilus DJ50 균주는 aflatoxin $B_1$에 대한 결합력을 나타내지 않았다. Aflatoxin $B_1$에 대한 유산균의 결합력과 결합속도는 독소의 농도, 반응시간 및 온도와 초기 세포수 등의 배양 조건에 따라 유의한 차이가 있었다. Aflatoxin $B_1$의 결합력은 세척 횟수에 따라 현저하게 감소하였고, 감소율은 살아있는 세포와 가열 처리한 세포에서 비슷하게 나타났다. 가열, 산성 pH, ${\alpha}$-amylase, protease, lysozyme 혹은 sodium metaperiodate의 처리에 의해 결합력이 유의하게 감소된 것으로 보아 주로 세포벽에 존재하는 당이나 단백질에 aflatoxin $B_1$이 결합되며, urea의 처리에 의해 결합력에 낮아지는 것은 이들 사이에는 소수성 결합이 작용하는 것으로 추정되었다.

• The Korean Journal of Physiology and Pharmacology
• /
• 제1권2호
• /
• pp.117-125
• /
• 1997

The N-methyl-D-aspartate (NMDA) receptor-mediated glutamatergic neurotransmission is involved in synaptic plasticity, developmental processes, learning and memory and many neuropathological disorders including age-related diseases. In the present study, regulation of the NMDA receptor properties by various ligands was investigated using $[^3H]MK-801$ binding studies in the synaptic membranes of young and aged rat forebrains. The binding in the presence of glutamate and glycine increased dramatically with growth between 1 and 6 weeks old, and thereafter declined gradually with aging. Glutamate, glycine or spermine respectively increased the binding with growth. Glutamate maintained the binding during aging, while glycine or spermine significantly decreased the binding in the aged brain. The maximum stimulation by glycine varied depending on the ages of brains. Greater sensitivity to glycine was observed at 1 week and 3 months and the sensitivity was significantly reduced in the aged brain. In contrast, spermine showed similar stimulation patterns in young and aged rats. These results indicated that the functional properties of the NMDA receptor-ion channel complex in young and aged rat forebrains are differentially regulated by agonists, and the reduction of the receptor function with normal aging may be, in some degree, due to the reduction of the receptor sensitivity to glycine.

• 한국자기공명학회논문지
• /
• 제20권3호
• /
• pp.71-75
• /
• 2016

The replication protein A (RPA) plays a crucial role in DNA replication, recombination, and repair. RPA consists of 70, 32 and 14 kDa subunits and has high single-stranded DNA (ssDNA) binding affinity. The largest subunit, RPA70, mainly contributes to bind to ssDNA as well as interact with many cellular and viral proteins. In this study, we performed nuclear magnetic resonance experiments on the complex of the DNA binding domain A of human RPA70 (RPA70A) with ssDNA, d(CCCCC), at various pH, to understand the effect of pH on the ssDNA binding of RPA70A. The chemical shift perturbations of binding residues were most significant at pH 6.5 and they reduced with pH increment. This study provides valuable insights into the molecular mechanism of the ssDNA binding of human RPA.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제8권2호
• /
• pp.112-116
• /
• 2003

An immunosensor based on surface plasmon resonance (SPR) onto a protein G layer by Self-assembly technique was developed for detection of Legionella pneumophila. The protein G layer by self-assembly technique was fabricated on a gold (Au) surface by adsorbing the 11-mercaptoundecanoic acid (MUA) and an activation process for the chemical binding of the free amino (-NH$_2$) of protein G and 11-(MUA) using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDAC) in series. The formation of the protein G layer by self-assembly technique on the Au Substrate and the binding of the antibody and antigen in series were confirmed by SPR spectroscopy. The Surface topographies of the fabricated thin films on an Au substrate were also analyzed by using an atomic force microscope (AFM). Consequently, an immunosensor for the detection of L. pneumophila using SPR was developed with a detection limit of up to 10$^2$CFU per mL.

• Journal of Microbiology and Biotechnology
• /
• 제12권5호
• /
• pp.780-786
• /
• 2002

An immunosensor based on surface plasmon resonance (SPR) with a self-assembled protein G layer was developed for the detection of Escherichia coli O157:H7. A self-assembled protein C layer on a gold (Au) surface was fabricated by adsorbing the mixture of 11-mercaptoundecanoic acid (MUA) and hexanethiol at various molar ratios and by activating chemical binding between free amine (-$NH_2$) of protein G and 11-(MUA) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDAC) in series. The formation of a self-assembled protein G layer on an Au substrate and the binding of the antibody and antigen in series were confirmed by SPR spectroscopy. The surface morphology analyses of the self-assembled protein G layer on the Au substrate, monoclonal antibody (Mab) against E. coli O157:H7 which was immobilized on protein G, and bound E. coli O157:H7 extracts on Immobilized Mab against E. coii O157:H7 were performed by atomic force microscopy (AFM). The detection limit of the SPR-based immunosensor for E. coli O157:H7 was found to be about $10^4$ cells/ml.

• 한국고분자학회:학술대회논문집
• /
• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
• /
• pp.37-38
• /
• 2006

Conjugated diacetylene supramolecules are interesting biomimetic materials in view of application to chemical and label-free biological sensors. These supramolecules are unique in changing color from blue to red upon specific binding events. Various binding events including viruses, toxins, glucose, and ionic interactions have been reported detectible. Here, we focus on fabrication of polydiacetylene supramolecule dot array patterns on solid substrates by using a conventional microarrayer. Each dot is found to possess the color-changing property as well as the fluorescence self-emission. This technique allows us, for the first time, to fabricate biochips based on polydiacetylene supramolecules. Label-free detection of small molecules and biological targets will be discussed.

• Bulletin of the Korean Chemical Society
• /
• 제32권12호
• /
• pp.4337-4340
• /
• 2011

The vitamin D receptor binding peptide, VDRBP, was overexpressed as a fused form with the ubiquitin molecule in Rosetta(DE3)pLysS, a protein production strain of Escherichia coli harboring an induction controller plasmid. The fusion protein was bound to the immobilized metal ions, and the denaturation and renaturation of the fusion protein were performed as a part of the purification procedure. After the elution of the fusion protein, the peptide hormone was released from its fusion partner by using yeast ubiquitin hydrolase (YUH), and subsequently purified by reverse phase chromatography. The purity of the resulting peptide fragment was checked by MALDI-TOF mass and NMR spectroscopy. The final yields of the target peptide were around 5 and 2 mg per liter of LB and minimal media, respectively. The recombinant expression and purification of this peptide will enable structural and functional studies using multidimensional NMR spectroscopy and X-ray crystallography.

• Carbon letters
• /
• 제8권4호
• /
• pp.292-298
• /
• 2007

In order to investigate functional groups on the surface of Multi-walled Carbon Nanotubes (MWCNTs) induced by oxyfluorination, XPS (X-ray photoelectron spectroscopy) analysis was carried out. All core level spectra of MWCNTs were deconvoluted to several Pseudo-Voigt functions (sum of Gaussian-Lorentzian functions). Both O1s and F1s binding energy of oxyfluorinated MWCNTs shifted high value as increment of fluorine mixing ratio. The carbon-fluorine covalent bonding concentration increased as increment of fluorine mixing ratio. The shape and intensity of OF10-MWCNTs are similar with those of as-received MWCNTs. However, the intensity and binding energies of main peak position of OF20-MWCNTs and OF30-MWCNTs were dramatically increased by oxyfluorination.

• 한국미생물생명공학회:학술대회논문집
• /
• 한국미생물생명공학회 2005년도 2005 Annual Meeting & International Symposium
• /
• pp.334-334
• /
• 2005