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Thien-Hoang Ho,Kyoungho Jung,Inho Lee,Kim-Hung Huynh,Diem-Quynh Nguyen,Hyunjae Park,Sang Hee Lee,Lin-Woo Kang 한국구조생물학회 2017 Biodesign Vol.5 No.1
The emergences of multi-drug resistant bacteria such as Acinetobacter baumanni have emphasized the necessity of new antibiotics. Peptidyl deformylase (PDF) catalyzes the removal of the formyl group from the N-terminal formylated methionine residue present in all nascent polypeptides in bacteria. In this study, the PDF gene from Acinetobacter baumannii K0420859 was cloned and its protein was overexpressed in E. coli, purified, and crystallized. The purified protein was crystallized using the hanging-drop vapour-diffusion method and the crystal diffracted to 2.4 Å resolution. The crystal belonged to the trigonal space group P3 2 with unit cell parameters of a = b= 39.4 Å and c = 187.9 Å. Two protomers were presented in the asymmetric unit with a corresponding V M of 2.10 Å 3 Da -1 and a solvent content of 41.5%.
Kim-Hung Huynh,홍명기,Clarice Lee,Huyen-Thi Tran,이상희,안예진,차선신,강린우 한국미생물학회 2015 The journal of microbiology Vol.53 No.11
Acinetobacter baumannii, which is emerging as a multidrugresistant nosocomial pathogen, causes a number of diseases, including pneumonia, bacteremia, meningitis, and skin infections. With ATP hydrolysis, the D-alanine-D-alanine ligase (DDL) catalyzes the synthesis of D-alanyl-D-alanine, which is an essential component of bacterial peptidoglycan. In this study, we determined the crystal structure of DDL from A. baumannii (AbDDL) at a resolution of 2.2 Å. The asymmetric unit contained six protomers of AbDDL. Five protomers had a closed conformation in the central domain, while one protomer had an open conformation in the central domain. The central domain with an open conformation did not interact with crystallographic symmetry-related protomers and the conformational change of the central domain was not due to crystal packing. The central domain of AbDDL can have an ensemble of the open and closed conformations before the binding of substrate ATP. The conformational change of the central domain is important for the catalytic activity and the detail information will be useful for the development of inhibitors against AbDDL and putative antibacterial agents against A. baumannii. The AbDDL structure was compared with that of other DDLs that were in complex with potent inhibitors and the catalytic activity of AbDDL was confirmed using enzyme kinetics assays.
( Kim-hung Huynh ),안재현,김형모,조아라,함은일,전봉현 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
In this work, 4-mercaptophenyl boronic acid (4-MPBA) was prepared for detect glucose by surface enhanced Raman scattering (SERS) on the surface of silver nanoparticle-embedded silica-coated graphene oxide (GO@SiO<sub>2</sub>@Ag NPs@MPBA). The SERS intensity of 4-MPBA on the GO@SiO<sub>2</sub>@Ag NPs was 2.2 times stronger than GO@Ag NPs. Also, silica-coated GO showed a low background signals comparing GO. The SERS intensity of GO@ SiO<sub>2</sub>@Ag NPs@MPBA peaked at 1 mM 4-MPBA. Then, pH-dependent behavior of 4-MPBA on the GO@SiO<sub>2</sub>@Ag NPs was investigated. The highest SERS signal intensity was indicated at pH 3. The 4-MPBA-incorporated GO@SiO<sub>2</sub>@Ag NPs which were united to glucose increased the SERS signals at both 1,072 and 1,588 cm<sup>-1</sup>. The range of glucose was estimated from 2 to 20 mM . These results provide a lot of application into detection of glucose and progress the SERS-based biosensors using graphene oxide as a substrate.
Xuan-Hung Pham,함은일,Kim-Hung Huynh,김형모,Byung Sung Son,Dae Hong Jeong,Bong-Hyun Jun 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.83 No.-
Toxic 4-aminophenol (4-AP) can be considered as a primary impurity during the synthesis and/or storageof N-acetyl-para-aminophenol (APAP). In this study, 4-AP was sensitively and selectively detected in thepresence of APAP using a gold–silver core–shell nanoparticle-embedded silica nanostructure(SiO2@Au@Ag). First, approximately 200 nm of SiO2@Au@Ag were successfully prepared based on theAu-seed (3 nm) mediated growth of Ag on the surface of SiO2 NP. Upon the incubation of 4-AP withSiO2@Au@Ag nanoparticles (NPs), the surface-enhanced Raman spectroscopy (SERS) intensity of 4-AP at1591 cm 1 increased proportionally in accordance with an increase in the concentration of 4-AP in therange of 0–800 mM, with a detection limit of 3.5 ppm. In addition, the APAP did not exhibit a significantRaman signal at high concentrations (5 mM) and under the NP incubation condition. In the presence of 1mM, 3 mM, and 5 mM of APAP, 4-AP was detected using SiO2@Au@Ag NPs within the range of 200–1000mM, although the slopes decreased from 0.083 cps/mM to 0.059 cps/mM, 0.068 cps/mM, and 0.035 cps/mM, respectively. This study provides a method for the detection of 4-AP in the presence of APAP by usingSiO2@Au@Ag for impurity detection in the pharmaceuticalfield.
Xuan-Hung Pham,함은일,Kim-Hung Huynh,Byung Sung Son,김형모,전봉현 한국바이오칩학회 2020 BioChip Journal Vol.14 No.2
The use of colorimetric bioassays for protein detection is one of the most promising diagnostic approaches, but their relatively poor detection limits have been a critical issue. In this study, we developed an efficient colorimetric bioassay based on antibody-coated peroxidase-mimicking Au nanoparticles (Au NPs) for the detection of prostate-specific antigen (PSA), which is one of the most widely used protein biomarkers for the diagnosis of prostate and breast cancers. Anti-PSA antibody adsorption on the Au NP surface result in 65% of the peroxidasemimicking properties of Au NPs was suppressed to maximize sensitivity of the assay. Anti-PSA antibody adsorption on the Au NP was optimized at 150 µg/mL anti-PSA4 antibody for 1 h incubation, and their surface was blocked with 2% BSA. The experimental conditions of the immunoassay detection were also investigated. A highest assay value was obtained at 10 µg/mL anti-PSA1 capture antibody using 3% BSA for surface blocking and at 2.5 pM anti- PSA4-Ab coated Au NPs for 1 h incubation with PSA antigen. As a result, PSA was detected at a wide range of 0.25 to 2,500 ng/mL with a detection limit of 0.23 ng/mL. The anti-PSA-Ab coated Au NP- based assay was simple, easy to operate, and sensitive. The proposed peroxidase-mimicking anti-PSA Ab-coated Au NPbased assay could be further developed to detect other protein biomarkers.
Pham, Xuan-Hung,Hahm, Eunil,Huynh, Kim-Hung,Son, Byung Sung,Kim, Hyung-Mo,Jeong, Dae Hong,Jun, Bong-Hyun MDPI AG 2019 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.20 No.19
<P>In this study, SiO2@Au@4-MBA@Ag (4-mercaptobenzoic acid labeled gold-silver-alloy-embedded silica nanoparticles) nanomaterials were investigated for the detection of thiram, a pesticide. First, the presence of Au@4-MBA@Ag alloys on the surface of SiO2 was confirmed by the broad bands of ultraviolet-visible spectra in the range of 320-800 nm. The effect of the 4-MBA (4-mercaptobenzoic acid) concentration on the Ag shell deposition and its intrinsic SERS (surface-enhanced Raman scattering) signal was also studied. Ag shells were well coated on SiO2@Au@4-MBA in the range of 1-1000 µM. The SERS intensity of thiram-incubated SiO2@Au@4-MBA@Ag achieved the highest value by incubation with 500 µL thiram for 30 min, and SERS was measured at 200 µg/mL SiO2@Au@4-MBA@Ag. Finally, the SERS intensity of thiram at 560 cm−1 increased proportionally with the increase in thiram concentration in the range of 240-2400 ppb, with a limit of detection (LOD) of 72 ppb.</P>
Tran, Phi-Long,Kim, Okwha,Tran, Huynh Nguyen Khanh,Tran, Manh Hung,Min, Byung-Sun,Hwangbo, Cheol,Lee, Jeong-Hyung Elsevier 2019 Food and chemical toxicology Vol.129 No.-
<P><B>Abstract</B></P> <P>The flower buds of <I>Cleistocalyx operculatus</I> are used as an important ingredient in herbal tea and herbal products in several tropical countries. However, their protective effects and underlying mechanisms on lipopolysaccharide (LPS)-induced endotoxic shock remain unclear. The aim of this study was to investigate the anti-inflammatory effects of ethanol extract of <I>C. operculatus</I> flower buds (ECO) and its major constituent 2′,4′-dihydroxy-6′-methoxy-3′,5′-dimethylchalcone (DMC) in macrophages and in an experimental LPS-induced sepsis mouse model. ECO inhibited the LPS-induced production and expression of pro-inflammatory mediators in macrophages. In an endotoxic shock mouse model, the oral administration of ECO rescued LPS-induced mortality, and attenuated LPS-induced increases in the serum levels of pro-inflammatory mediators, and damage of the lung and liver tissues. ECO increased the nuclear translocation of the nuclear factor erythroid 2-related factor 2 (Nrf2), as well as the expression of Nrf2 target genes, including heme oxygenase-1 (HO-1), in macrophages. Similar to the effects of ECO, DMC also inhibited the LPS-induced inflammatory response in macrophages and endotoxic shock in mice, and activated the Nrf2/HO-1 pathway. In conclusion, our findings suggested that ECO and its major constituent, DMC, attenuated LPS-induced endotoxic shock by activating the Nrf2/HO-1 pathway.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The flower buds of Cleistocalyx operculatus are used as an ingredient in herbal products in several tropical countries. </LI> <LI> The anti-inflammatory effects of C. operculatus flower buds (ECO) and its major constituent DMC are demonstrated. </LI> <LI> ECO and DMC attenuates lipopolysaccharide-induced inflammatory response in macrophages and endotoxic shock in mice. </LI> <LI> The Nrf2/HO-1 pathway is attributable to the anti-inflammatory properties of ECO and DMC in macrophages. </LI> <LI> The mechanism explains the anti-inflammatory effects of ECO and DMC. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Crystal Structure of XoLAP, a Leucine Aminopeptidase, from Xanthomonas oryzae pv. oryzae
김진광,Sampath Natarajan,박한슬,Kim-Hung Huynh,이상희,김정구,안예진,강린우 한국미생물학회 2013 The journal of microbiology Vol.51 No.5
Aminopeptidases are metalloproteinases that degrade N-terminal residues from protein and play important roles in cell growth and development by controlling cell homeostasis and protein maturation. We determined the crystal structure of XoLAP, a leucyl aminopeptidase, at 2.6 Å resolution from Xanthomonas oryzae pv. oryzae, causing the destructive rice disease of bacterial blight. It is the first crystal structure of aminopeptidase from phytopathogens as a drug target. XoLAP existed as a hexamer and the monomer structure consisted of an N-terminal cap domain and a C-terminal peptidase domain with two divalent zinc ions. XoLAP structure was compared with BlLAP and EcLAP (EcPepA) structures. Based on the structural comparison, the molecular model of XoLAP in complex with the natural aminopeptidase inhibitor of microginin FR1 was proposed. The model structure will be useful to develop a novel antibacterial drug against Xoo.