환경오염물질 검출을 위한 전기화학발광 프로브에 관한 연구

학위논문(박사) -- 서울대학교대학원 : 자연과학대학 화학부, 2022. 8. 홍종인.인간의 산업적 활동과 기술의 진보는 중금속, 준금속, 그리고 유기 오염물질과 같은 유해 폐기물의 대량 유출을 수반하여 심각한 환경오염을 야기하고 있다. 이러한 환경오염물질들은 일반적으로 잔류성, 생물축적성, 그리고 독성을 지니고 있어 인간의 건강에 심각한 문제를 일으킬 수 있다. 따라서, 자연에서 이러한 환경오염물질들을 검출하고, 지속적으로 모니터링하는 것이 매우 중요하다. 환경오염물질들을 검출하기 위한 방법 중 하나인 화학 센서는 최근 수년간 관련 연구자들에게 큰 관심을 끌어온 주제이다. 그중에서 전기화학적발광 기반 화학 센서는 기존에 있던 분석법들에 비해 더 낮은 바탕 신호, 뛰어난 재현성, 높은 감도 및 선택성 등의 장점들을 가지고 있다. 또한, 이것은 장비와 검출 방법들을 간소화 할 수 있기 때문에 독성오염물질의 현장 검출을 위한 유망기술로 평가받고 있다. 이 논문은 고리형 이리듐(III) 복합체를 활용해 환경오염물질 검출을 위한 전기화학적발광 센서의 개발에 대하여 기술하였다. 우리는 고리형 이리듐(III) 복합체에 반응 및 결합자리를 도입함으로써 다양한 목표분자들을 선택적으로 검출할 수 있는 분자들을 합성하였다. 이 분자들은 특정 환경오염물질과 반응 및 결합하여 분자의 전기적 성질의 변화가 유도되고, 전기화학적발광 신호의 변화가 나타나게 된다. 이를 기반으로, 우리는 이리듐(III) 기반 발광체, 반응 및 결합자리, 분석물질들에서 나타나는 화학적 상호작용에 대해 체계적으로 연구할 수 있었고, 최종적으로 이 센서들을 이용해서 다양한 환경오염물질에 대한 정량에 성공할 수 있었다. 1부는 전기화학적발광에 대한 전반적인 내용을 다룬다. 먼저, 전기화학적 발광에 대한 기초 이론과 발광체에 대해 정리한 후, 이리듐(III) 기반 전기화학적 발광체에 대해 자세히 기술하였다. 그리고 전기화학적발광 기반 단분자 센서를 개발하기 위한 기초적인 원리와 전략을 서술하였다. 2부는 고리형 이리듐(III) 복합체 기반 탐지체들을 이용하여 싸이오페놀과 황화수소 같은 활성 황 종들의 검출에 적용한 사례를 다룬다. 먼저, 싸이오페놀의 빠른 검출을 위한 고리형 이리듐(III) 복합체 기반 전기화학적발광 화학 정량계의 개발에 관해 기술하였다. 이 합성탐지체의 설계 전략은 다음과 같다.: 1) 강한 전기화학적 발광이 나타난다고 알려진 주리간드가 페닐이소퀴놀린이고, 보조리간드가 아세틸아세톤인 고리형 이리듐 복합체를 발광체로 선택하였다.; 2) 발광체에 광유발 전자 전달 소광 물질로 알려진 디니트로페닐(DNP)기를 싸이오페놀에 대한 반응자리로써 도입되었다.; 3) 전자 받개인 포르밀기는 반응 속도를 가속화시키기 위해 추가적으로 도입되었다. 이러한 원리에 근거하여 합성된 탐지체는 싸이오페놀 존재시 친핵성 방향족 치환 반응이 일어나 DNP기가 이탈되고, 전기화학적발광 신호의 증가가 유도되었다. 탐지체의 전기화학적발광 세기는 싸이오페놀의 농도와 0–200 µM 범위에서 선형 상관관계를 보여주었다. 또한, 다른 음이온이나 생체싸이올과 반응하지 않고 오직 싸이오페놀과만 반응함으로써 뛰어난 선택성을 보여주었다. 또한, 탐지체는 실제 물 시료에서 싸이오페놀의 농도를 정량하는데 성공함으로써 전기화학적발광 기반의 현장 검출을 위한 새로운 개념증명을 제공하였다. 다음으로, 황화수소 검출을 위한 이리듐(III) 복합체 기반의 전기화학적발광 화학센서의 개발에 대해 기술하였다. 이 탐지체의 설계 전략은 다음과 같다.: 1) 주리간드가 페닐피리딘이고, 보조리간드가 이미다졸-페난트롤린인 고리형 이리듐(III) 복합체를 발광체로 선정하였다.; 2) 광유발 전자 전달 소광체이자 황화수소에 대한 반응자리로써 두 개의 니트로벤조옥사디아졸(NBD)기를 보조리간드에 도입하였다. 탐지체에 도입된 두 NBD기는 계층적 반응성이 나타나 황화수소에 대해서만 선택적으로 모든 NBD기가 이탈될 수 있다. 따라서, 탐지체는 광발광분석에서 다양한 분석물들에 대해서 비특이적 바탕/간섭 신호를 나타냈지만, 전기화학적발광에서는 황화수소에 대해 선택적인 신호 증가가 유도될 수 있었다. 탐지체의 전기화학적발광 세기는 황화수소의 농도와 0–40 µM 범위에서 선형 상관관계를 보여주었다. 마지막으로, 이 탐지체는 수돗물 시료 및 상업용 황화암모늄 용액에서 황화수소를 성공적으로 정량함으로써 현장 검출에서의 사용 가능성을 보여주었다. 3부는 고리형 이리듐(III) 복합체 기반 탐지체들을 이용하여 수은 이온과 글리포세이트 같은 환경 오염물질들의 검출에 적용한 사례를 다룬다. 먼저, 수은 이온의 선택적 검출을 위한 고리형 이리듐(III) 복합체 기반 전기화학적발광 화학 정량계의 개발에 관해 기술하였다. 이 탐지체의 설계 전략은 다음과 같다.: 1) 주리간드가 페닐이소퀴놀린이고, 보조리간드가 바이피리딘인 고리형 이리듐(III) 복합체를 발광체로 선정하였다.; 2) 수은이온에 대한 반응자리 및 신호 조절자로써 o-아미노메틸페닐붕소산를 보조리간드에 도입하였다. 이러한 원리를 바탕으로 설계된 탐지체는 수은 이온과 즉각적인 금속 교환 반응을 통해 광유발 전자 전달 소광이 나타나는 물질을 생성으로써, 전기화학적발광 신호의 감소를 유도하였다. 탐지체의 전기화학적발광 세기는 수은 이온의 농도와 0–10 µM 범위에서 선형 상관관계를 보여 주었다. 또한, 탐지체는 다양한 금속 이온들로부터 수은 이온을 성공적으로 구별할 수 있었다. 마지막으로, 이 탐지체는 수돗물 시료에서 수은 이온의 농도를 성공적으로 정량함으로써 현장 검출을 위한 센서로의 가능성을 보여주었다. 다음으로는, 글리포세이트와 선택적인 결합 후에 전기화학적 발광 신호의 증가가 유도되는 합성탐지체에 대해 기술하였다. 이 탐지체의 설계 전략은 다음과 같다.: 1) 주리간드가 페닐이소퀴놀린이고, 보조리간드가 바이피리딘인 고리형 이리듐(III) 복합체를 발광체로 선정하였다.; 2) 글리포세이트에 대한 결합자리로써 구리(II)-다이피코릴아민(Cu(II)-DPA)를 메틸렌 연결부를 이용하여 주리간드에 도입하였다. 이러한 구조적 특성에 의해서 프로브의 전기화학적발광은 이리듐(III) 복합체의 여기 상태에서 상자성 Cu(II) 이온으로의 전자 전달에 의해 소광 되었다. 하지만, 글리포세이트가 DPA 리간드에 배위된 Cu(II) 이온에 결합하면 구리(II) 이온의 양전하가 감소하고 구리(II) 이온과 DPA 사이의 결합이 약해져서 프로브의 여기상태에서 Cu(II)로의 전자 전달이 무효화된다. 따라서, 프로브의 전기화학적발광 신호는 GlyP가 있을 때 크게 증가되었다. 탐지체의 전기화학적발광 세기는 글리포세이트의 농도와 0–200 µM 범위에서 선형 상관관계를 보여주었다. 또한, 탐지체는 다양한 음이온 및 제초제로부터 글리포세이트를 성공적으로 구별할 수 있었다. 마지막으로, 탐지체는 수돗물 시료에서 글리포세이트의 농도를 성공적으로 정량화하여 현장 검출을 위한 센서로의 잠재력을 입증하였다. 4부는 새로운 유기화합물 기반 전기화학적 발광체의 개발에 대해 다룬다. 기존에 전기화학적발광 분석에서 사용된 대표적인 발광체는 루미놀과 루테늄(II) 복합체이다. 하지만, 루미놀은 전기화학적 발광 과정 중에 물질이 소진되고, 높은 염기 상태가 요구 된다. 루테늄(II) 복합체의 경우, 낮은 금속 내 전이 상태 에너지로 인해 분자 구조의 개질을 통해 파장을 변화시키기 어렵다. 또한, 백금족 금속의 높은 가격과 제한된 공급도 큰 문제로 작용하고 있다. 따라서, 이들을 대체할 수 있는 새로운 전기화학적발광 분석용 발광체의 개발이 시급하다. 이러한 문제를 극복하고자, 우리는 새로운 유기 전기화학적 발광체 1–5개발하였다. 분자들의 기본 골격은 옥사아자보린이 공유결합으로 연결된 나프탈렌으로 ICT를 유도하기 위해 나프탈렌에 디에틸아미노 그룹을 도입하였다. 이 전기화학적 발광체들은 트리프로필아민 라디칼과 발광체 양이온 라디칼 사이의 반응 엔탈피가 충분하지 않아도 추가적인 보조의 전기화학적 발광 과정 덕분에 뛰어난 전기화학적 발광 효율을 보여주었다. 물질 중, 발광체 2는 Ru(bpy)32+ 대비 1.36배 높은 전기화학적발광 효율을 나타냄으로써 환경오염물질 검출을 위한 전기화학적발광 센서의 기본골격으로 활용될 가능성을 제시하였다.Industrial human activities and technological progress are accompanied by many hazardous waste such as heavy metals, metalloids, and organic pollutants, causing serious environmental pollution. These environmental pollutants are generally persistent, bioaccumulative and toxic substances, which can cause serious health problems. Therefore, it is crucial to detect and continuously monitor the environmental pollutants in nature. The chemosensor, which is one of the methods for detecting environmental pollutants, has attracted considerable attention from related researchers in recent decades. Among them, the electrochemiluminescent (ECL) chemosensors have advantages such as a low background signal, excellent reproducibility, high sensitivity, and selectivity compared to conventional analytical methods. Furthermore, ECL is evaluated as a promising technology for the on-site detection of toxic pollutants since the instrument can be made into a miniaturized portable device and the analysis method can be simplified. This dissertation describes the development of ECL sensors based on a cyclometalated iridium(III) complex for the detection of environmental pollutants. We have developed probes that can selectively detect various target molecules by introducing a reaction or binding site into the cyclometalated iridium(III) complex. These probes react or bind with specific environmental pollutants to induce an alteration in the electronic properties of the molecules, thereby changing the ECL signals. Based on these characteristics, we could systematically study the chemical interactions between iridium(III)-based luminophore, reaction or binding sites, and analytes, and successfully quantify various environmental pollutants using these sensors. Part 1 describes a general introduction to ECL. First, the basic theory of ECL and ECL luminophores is summarized, and then the iridium (III) complex-based ECL luminophores are described in detail. The basic principles and strategies for the development of ECL-based molecular sensors are also described. Part 2 focuses on the development of cyclometalated iridium(III) complex-based probes for the detection of reactive sulfur species such as thiophenol (PhSH) and hydrogen sulfide (H2S). First, the development of a cyclometalated iridium (III) complex-based ECL chemodosimeter for the rapid detection of PhSH is described. The design strategy of this synthetic probe was based on the following: 1) A cyclometalated iridium (III) complex with phenylisoquinoline as a main ligand and acetylacetone as a ancillary ligand was selected as the luminophore because it exhibits strong ECL emission; 2) 2,4-dinitrophenyl (DNP) group, a well-known photoinduced electron transfer (PeT) quencher, was introduced as a reaction site for PhSH; 3) an electron-withdrawing formyl group was introduced to accelerate the reaction rate. Based on this rationale, the synthetic probe reacts with PhSH via a nucleophilic aromatic substitution, resulting in the cleavage of the DNP group and an increase in the ECL signal. The ECL intensity of the probe showed a linear correlation with the concentration of PhSH in the range of 0–200 µM. In addition, it exhibited remarkable selectivity toward PhSH over other anions and biothiols. Finally, the probe was successfully applied to quantify PhSH in real water samples, providing a new proof-of-concept for on-site detection based on ECL. Next, the development of an iridium(III) complex-based ECL chemodosimeter for the detection of H2S is described. The probes have two components: 1) A cyclometalated iridium(III) complex with phenylpyridine as the main ligand and imidazole-phenanthroline as the ancillary ligand was chosen as the ECL luminophore; 2) Two nitrobenzoxadiazole (NBD) groups, a well-known strong electron acceptor, was introduced into the ancillary ligand as a PeT quencher and a reaction site for H2S. The two NBD groups introduced into the iridium(III) complex have hierarchical reactivity, and all NBD groups could be selectively released only in the presence of H2S. Therefore, a selective signal enhancement of the probe toward H2S was observed in ECL analysis, while it showed non-specific background/interference signals for various analytes in PL analysis. The ECL intensity of the probe showed a linear correlation with the concentration of H2S in the range of 0–40 µM. Finally, the probe could successfully quantify H2S in tap water samples and commercial ammonium sulfide solutions, demonstrating the effectiveness of this probe for on-site detection. Part 3 presents the development of cyclometalated iridium(III) complex-based probes for the detection of environmental pollutants such as mercury ions (Hg2+) and glyphosate (GlyP). First, the development of a cyclometalated iridium(III) complex-based ECL chemodosimeter for the selective detection of Hg2+ ions is described. The design strategy of the probe was based on the following: 1) A cyclometalated iridium(III) complex with phenylisoquinoline as the main ligand and bipyridine as the ancillary ligand was selected as an ECL luminophore; 2) o-aminomethylphenylboronic acid was introduced into the ancillary ligand as an ECL signaling modulator and a reaction site for Hg2+ ions. Based on this rationale, the probe reacts with Hg2+ ions via transmetalation reaction to produce a molecule that exhibits PeT quenching, thereby decreasing the ECL signal. The ECL intensity of the probe showed a linear correlation with the concentration of Hg2+ ions in the 0–10 µM range. Additionally, the probe could successfully discriminate Hg2+ ions from various metal ions. Finally, the successful quantification of Hg2+ ion in tap water samples with ECL analysis demonstrated the effectiveness of the probe in on-site detection. Next, a synthetic probe in which an increase in the ECL signal is induced after selective binding with glyphosate is described. The design strategy of the probe toward GlyP was based on the following: 1) A cyclometalated iridium(III) complex with phenylisoquinoline as the main ligand and bipyridine as the ancillary ligand was selected as an ECL luminophore.; 2) Copper(II)-dipicolylamine (Cu-DPA) complex as a binding site for GlyP was tethered to the main ligand of the probes by a methylene linker. Based on these structural characteristics, ECL signals of the probes were quenched by electron transfer from the iridium(III) 3MLCT excited state to the paramagnetic Cu(II) ion. When GlyP is bound to the Cu(II) ion coordinated to the appended DPA ligand, the positive charge on Cu(II) ion was reduced and the bond between Cu(II) ions and DPA was weakened, thus nullifying electron transfer from an excited state of probes to Cu(II) center. Therefore, the ECL signal of the probe was significantly enhanced in the presence of GlyP. The ECL intensity of the probe showed a linear correlation with the concentration of GlyP in the range of 0–200 µM. In addition, the probe could successfully discriminate glyphosate from various anions and herbicides. Finally, the probe successfully quantified the concentration of GlyP ions in tap water samples, thus demonstrating the potential of the probe for on-site detection. Part 4 focuses on the development of novel organic ECL luminophores. Representative ECL luminophores used in ECL various analysis systems are luminol and tris(2,2-bipyridine)ruthenium(II) (Ru(bpy)32+). However, luminol is consumed during the process of ECL emission, and highly basic conditions are required. In the case of the Ru(bpy)32+, it is difficult to change the wavelength with the modification of molecular structure due to a low metal-centered state (MC state), which limits the use of multicolor analysis. In addition, the high price and limited supply of platinum group metals make it urgent to develop alternative ECL luminophores. To overcome these problems, we developed novel organic ECL luminophores. The basic skeleton of luminophores was the naphthalene directly linked through a covalent bond with oxazaborine, and a diethylamino group was introduced into naphthalene to induce intramolecular charge transfer (ICT). Although the reaction enthalpies between the tripropylamine radical and the radical cations of the luminophores were insufficient, compounds showed excellent ECL efficiencies due to the additional ECL processes. Among the compounds, 2 showed 1.36 times higher ECL efficiency relative to Ru(bpy)32+, suggesting its feasibility as an efficient ECL luminophore for the development of sensors that detect environmental pollutants.Part I. Background 1 Section 1. Electrochemiluminescence (ECL) 2 1. Introduction to ECL 2 2. ECL mechanisms 4 3. ECL luminophores 12 Section 2. Cyclometalated iridium(III) complexes 20 1. Color-tuning strategies in cyclometalated Iridium(III) complexes 20 2. Iridium(III) complexes for ECL 26 Section 3. Designing molecular ECL probes 30 1. General strategy 30 2. ECL signaling strategies 31 Part II. Electrochemiluminescent Probes for Detection of Reactive Sulfur Species Based on Cyclometalated Iridium(III) Complexes 37 Section 1. Background 38 1. Thiols 38 Section 2. Electrogenerated Chemiluminescent Chemodosimeter Based on a Cyclometalated Iridium(III) Complex for Sensitive Detection of Thiophenol 42 1. Introduction 42 2. Result and discussion 45 3. Conclusion 55 4. Experimental section 56 Section 3. Highly Selective Electrochemiluminescent Chemosensor for Sulfide Enabled by Hierarchical Reactivity 67 1. Introduction 67 2. Result and discussion 69 3. Conclusion 84 4. Experimental section 84 Part III. Electrochemiluminescent Probes for Toxic Pollutants Based on Cyclometalated Iridium(III) Complexes 96 Section 1. Background 97 1. Heavy metal ions and herbicides 97 Section 2. An Electrochemiluminescent Cyclometalated Iridium(III) Complex with Boronic Acid-Functionalized Ancillary Ligand for Detection of Mercury(II) Ion 102 1. Introduction 102 2. Result and discussion 104 3. Conclusion 116 4. Experimental section 116 Section 3. An Electrochemiluminescent Probe Based on Cyclometalated Iridium(III) Complex for Detection of Glyphosate 127 1. Introduction 127 2. Result and discussion 130 3. Conclusion 145 4. Experimental section 145 Part IV. Development of Organic ECL emitters 156 Section 1. Background 157 1. Organic ECL luminophores 157 Section 2. Electrochemiluminescence of Novel Oxazaborin Luminophores Based on Naphthalene Backbone 165 1. Introduction 165 2. Result and discussion 166 3. Conclusion 176 4. Experimental section 177 References and Notes 186 국문초록 199박

젖산 유도 저산소증 반응의 핵심 물질인 NDRG3의 구조 및 생물리학적 정의

학위논문(박사)--서울대학교 대학원 :약학대학 약학과,2020. 2. 한병우.The N-Myc downstream-regulated gene (NDRG) has been known to play promiscuous roles in cell proliferation, differentiation, and hypoxia-induced cancer metabolism. Especially, NDRG3 is related to proliferation and migration of prostate cancer cells. Furthermore, it has been reported to implicate lactate-triggered hypoxia responses and tumorigenesis. However, molecular mechanisms of the functions of NDRG3 remain unclear. Here, I report the crystal structure of human NDRG3 at 2.2 Å resolution with one homohexamer in an asymmetric unit. Although NDRG3 adopts an α/β-hydrolase superfamily fold, complete substitution of non-catalytic residues for the canonical catalytic triad and steric hindrance around the pseudo-active site seem to disable catalytic functions of α/β-hydrolase. NDRG3 shares a high similarity to NDRG2 in terms of amino acid sequence and structure. Interestingly, NDRG3 exhibits remarkable structural differences in a flexible loop corresponding to helix α6 of NDRG2 that is responsible for tumor suppression. Thus, this flexible loop region seems to play a distinct role in oncogenic progression induced by NDRG3. Collectively, these studies could provide structural and biophysical insights into the molecular characteristics of NDRG3.N-Myc downstream-regulated gene 단백질은 α/β-hydrolase 구조를 지니고 있는 군으로 지금까지 세포 증식, 분화, 그리고 저산소증에서 유도되는 암세포의 대사에 큰 영향을 끼치는 것으로 보고되었다. NDRG 단백질 군은 4가지 동형 단백질이 존재하며 이 중 NDRG3 단백질은 전립선 암에서의 증식 및 전이와 밀접하게 관련이 있으며, 특히 젖산 유도의 저산소증 반응 및 종양 발생에서 핵심적인 역할을 할 것으로 밝혀졌다. 본 논문에서는 NDRG3 단백질의 결정 구조를 2.2 Å 해상도로 구조를 규명하고, NDRG3 단백질의 생물물리학적 특징을 제시하였다. NDRG3는 용액 상에서 단량체 혹은 이량체로 존재하며 결정 구조를 통해 이량체의 결합 구조를 제시하였다. NDRG3는 구조적으로 α/β-hydrolase 부류와 비슷하지만 활성 부위에 핵심적인 잔기가 비활성화된 잔기로 변형되어 있어 가수분해 기능이 없을 것으로 추측할 수 있다. 또한 NDRG3의 구조는 기존에 밝혀진 NDRG2 단백질과 아미노산 서열, 구조적으로 비슷하지만, NDRG2의 종양억제기능으로 핵심적인 α6 헬릭스 구조 부분이 유연한 루프 형태로 바뀐 것을 확인할 수 있었다. 이러한 구조적 차이를 토대로 NDRG3는 종양억제기능을 가진 NDRG2와는 다른 역할을 할 것으로 유추한다. 따라서, 본 연구결과는 NDRG3의 분자 범위에서의 연구를 수행하는데 구조적, 생물물리학적 특징을 제시하였다.1. Introduction 1 1.1. The α/β-hydrolase fold 1 1.2. N-Myc downstream-regulated gene family 3 1.3. Expression level and functions of NDRG3 10 1.4. Purpose of this study 17 2. Materials and Methods 18 2.1. Cloning, protein expression, and purification of NDRG3 18 2.2. Mutagenesis and purification of NDRG3 23 2.3. Crystallization 28 2.4. X-ray data collection, refinement and structure determination 34 2.5. Size exclusion chromatography with multi-angle light scattering (SEC-MALS) analysis 38 2.6. Circular Dichroism (CD) 39 2.7. Surface Plasmon Resonance (SPR) 39 2.8. Molecular dynamics and docking study 40 2.9. Data deposition 41 3. Results 42 3.1. Overall structure of human NDRG3 contains an α/β-hydrolase fold domain and a small cap-like domain. 42 3.2. Crystal packing of NDRG3 structure indicates dimeric interface. 50 3.3. Structural comparison with α/β-hydrolase supports loss of enzymatic function in NDRG3. 57 3.4. NDRG3 shows a structural similarity to NDRG2 and contains a distinctive disordered region and a solvent accessible cavity. 62 3.5. Unfolded helix α6 region of NDRG3 is a flexible loop. 71 3.6. In vitro binding assays on NDRG3 against lactate. 78 3.7. Crystal structures of NDRG3 supplemented with different L-lactate concentrations. 82 3.8. Computational docking simulation study on NDRG3 against L-lactate. 88 4. Discussion 91 5. Conclusion 100 References 101 초 록 106 Acknowledgements 108Docto

朝鮮時代 使行과 使行記錄

The international relationship in traditional East Asia was based on a Tribute/recognition system(朝貢體制) and was performed through a diplomatic form of sahaeng(使行). The development of an issue, setting diplomatic goals, granting a name of sahaeng, and deciding the right time and size comprised the procedures of sahaeng. Especially, as the governing system of China, after the Ming Dynasty, was strictly based on documentation, the justification of sahaeng for delivering documents of the Joseon Dynasty King was emphasized, while individual diplomatic activities of sahaeng"s members were restricted. Due to such restriction, Tongsa(通事), based on language ability, acted as practical diplomats. While the diplomatic role of Tongsa increased, messengers and other staffs had enough time to experience various cultures during the period of sahaeng, and kept these accounts for the sahaeng record(使行記錄). Although Sasinbyeoldan(使臣別單), which is recorded in the diplomatic documentation of Joseon"s Tongmunhwigo(同文彙考), was not an official diplomatic document, it had the vale of an official sahaeng record. Sasinbyeoldan consisted of the byeoldan of sasin, the mungyeonsageon(聞見 事件) of seojangkwan, and the subon(手本) of yeogkwan, and was not restricted to any method of description. The official sahaeng record submitted to sengjeongwon formed the bases for private sahaeng records that were arranaged by individual sahaeng"s members, and the sahaeng"s members, who did not have the responsibility to submit records to seungjeongwon, left sahaeng records in collections more freely. Sahaeng records were a kind of an account of one"s trip to China. They showed the Joseon-China relationship and the overall cultural exchanges of East Asia in detail. They have meaning in that they show how the sadaebu of Joseon engaged in exchanges with Chinese scholars

Human Cytosolic Aspartyl-tRNA Synthetase에 대한 구조 연구

학위논문 (석사)-- 서울대학교 대학원 : 약학과, 2014. 2. 한병우.Human cytosolic aspartyl-tRNA synthetase (DRS)는 단백질의 translation 과정에 관여하는 aminoacyl-tRNA synthetase (aaRS)의 한 요소로써, aspartic acid와 그것을 인식하는 특정 tRNA를 연결하는 효소이다. 또한 DRS는 체내에서 multi-tRNA synthetase complex (MSC)를 이루는 단백질로 알려져 있으며 이들 MSC는 체내에서 aaRS들의 저장소의 역할을 하면서 translation과 non-canonical function을 조절한다고 알려져 있으나 DRS의 non-canonical function은 아직 밝혀지지 않은 실정이다. 본 연구에서는 X선을 이용하여 DRS의 결정으로부터 2.25 Å resolution의 회절자료를 얻어 DRS의 구조를 규명했다. DRS의 결정구조로부터 DRS는 homodimer이며 mitochondrial aspartyl-tRNA synthetase와 비교해 보았을 때, sequence상에서는 22.9%의 낮은 유사성을 띠나 구조적으로는 r.m.s.d. distance가 1.7 Å으로 유사한 것을 밝혔다. 그리고 DRS의 N-terminus 부분에서 N-helix를 유추할 수 있었고 이 구조가 DRS와 tRNAAsp간의 상호작용을 조절할 것으로 예상했다. 또한 post-translational modification (PTM) sites를 분석하여 새로운 PTM sites를 발견했으며 이 부분들이 DRS 와 tRNAAsp사이에 위치할 것으로 보아 이들간의 결합에 영향을 미칠 것으로 예상했다. 146번 serine은 dimeric interface이면서 인산화하는 부분으로 146번 serine의 인산화가 DRS의 구조 변화를 유도하여 DRS의 기능을 조절할 것으로 본다. DRS의 결정구조는 MSC상에서의 DRS의 결합상태를 확인하고 DRS의 새로운 기능을 밝히는데 도움이 될 것으로 기대한다.Human cytosolic aspartyl-tRNA synthetase (DRS), a component of aminoacyl-tRNA synthetase (aaRS), is an enzyme that attaches the aspartic acid to its cognate tRNA in RNA translation process. Also it composes multi-tRNA synthetase complex (MSC) in combination with 8 cytosolic aaRSs and 3 aminoacyl tRNA synthetase complex-interacting multifunctional proteins, which is known as a reservoir for aaRSs and regulates aaRSs between their translational functions and non-canonical functions. Non-canonical function of DRS has not been revealed yet. We solved the crystal structure of DRS at 2.25 Å resolution. From the crystal structure, we revealed that DRS is a homodimer with a dimer interface 3,750.5 Å2 which is 16.6% of the monomeric surface area. When compared with mitochondrial DRS, they share only 22.9% sequence identity but are structurally similar to each other with r.m.s.d. distance of 1.7 Å. Our structure supports the switching model of the N-helix in DRS which was proposed to control the binding affinity between DRS and tRNAAsp, by showing the C-terminal end of the N-helix. And post-translational modification (PTM) of DRS analyses found new PTM sites that seem to affect the interaction of DRS and tRNAAsp. Ser146 residue located in dimeric interface of DRS is one of phosphorylation sites, and we imply that the phosphorylation of Ser146 triggers the conformational change of DRS which could be related with unforseen function. Our structural study might help to elucidate its interactions in MSC and shed light on its non-canonical functions.Contents Abstract i Contents ii List of figures iii List of table iii I. Introduction II. Materials and Methods 1. Materials 2. Methods 2.1. Cloning 2.2. Overexpression 2.3. Purification 2.4. Crystallization 2.5. X-ray data collection and structure determination 2.6. Post-translational modification analysis 2.7. Mutagenesis 2.8. Structure determination of DRS S146D mutant III. Results and Discussion 1. Cloning 2. Overexpression and Purification 3. Crystallization 4. X-ray data collection and structure determination 5. Structural comparison between DRS and DRS2 6. N-terminal extension of DRS 7. PTM studies of DRS 8. Key intermolecular interaction of DRS dimer. 9. Site-directed mutations in DRS 10. Structure determination of DRS S146D mutant IV. References V. Acknowledgment Abstract in KoreanMaste

Raman Scattering of 4-Aminobenzenethiol and Its Analog Molecules on Ag, Au, and Pt Nanostructures: Contribution of Photoinduced Charge-Transfer

학위논문 (박사)-- 서울대학교 대학원 : 화학부, 2013. 2. 김관.The surface-enhanced Raman scattering (SERS) of 4-aminobenzenehtiol (4-ABT) has seen a surge of interest recently, since its SERS spectral features are dependent not only on the kinds of SERS substrates but also on the measurement conditions. A problem was initially encountered in the interpretation of the SERS spectrum of 4-ABT due to difficulty in correlating several peaks therein with the normal Raman peaks, but the SERS spectral pattern of 4-ABT looked similar to that of 4,4′-dimercaptoazobenzene (4,4′-DMAB). To clarify the issue, the SERS characteristics of 4-ABT and its analog molecules adsorbed on metal surfaces are carefully reinvestigated to understand the charge-transfer chemical enhancement mechanism in this Ph.D. thesis. In chapter 1, the general overview of the Raman scattering theory and SERS mechanisms are described concisely. SERS is an abnormal surface optical phenomenon resulting in strongly increased Raman signals for molecules adsorbed onto nanostructured coinage metals. In recent years, it has been reported that even single-molecule detection is possible by surface-enhanced resonance Raman scattering (SERRS), suggesting that the enhancement factor (EF) can reach as much as 1014-1015. Two enhancement mechanisms, one called a long-range electromagnetic (EM) effect and the other called a short-range charge-transfer (CT) chemical effect, are simultaneously operative. Both mechanisms suggest the possibility of enhanced absorption and enhanced photochemistry for surface-adsorbed molecules. In chapter 2, the current status of SERS studies on 4-ABT are described. For a long time, 4-ABT, also known as p-aminothiophenol (PATP) or p-mercaptoaniline (pMA), is one of the important surface probe molecules in SERS community and the nanoscience field. The main reasons are that 4-ABT molecules are strongly and easily adsorbed onto the most metal substrates and generate a strong and unique SERS signal which is very sensitive to the type of substrates and measurement conditions. The normal Raman (NR) spectrum of 4-ABT is mostly featureless in the region of 1100~1500 cm-1, but three to four peaks appear newly in that region in its SERS spectra. Since these peaks can be assigned to the b2-type vibration, which are arising from charge transfer process through the Herzberg-Teller vibronic coupling term, 4-ABT has been regarded for two decades as a model adsorbate for probing the CM effect in SERS. Very recently, however, a number of researchers have come up with a different explanation for the appearance of these b2-type bands that the b2-type bands appearing in the SERS of 4-ABT must be the N=N stretching vibrations of 4,4-DMAB produced from 4-ABT via a catalytic coupling reaction on the metal substrates. The elucidation of the SERS characteristics of 4-ABT and its analog molecules including 4,4-DMAB is thus needed to see another or why we have made a wrong assignment during the past 15 years. In chapter 3, the SERS characteristics of 4-ABT and 4-ABT adsorbed on Pt nanoparticles are investigated. Pt is a well-known catalyst that has a high catalytic activity. It is found, however, that 4-nitrobenzenethiol (4-NBT) is barely subjected to photoreaction on a Pt surface. On the contrary, the SERS spectra of 4-ABT on Pt clearly show that the b2-type bands are increasing in relative intensity toward shorter wavelength. In addition, the SERS spectral pattern of 4-ABT on Pt is variable not only with changes in the electrode potential but also by altering the excitation wavelength. These spectral variations could be understood by presuming that the chemical enhancement mechanism is also operating in this system, along with the electromagnetic enhancement. Interestingly, similar spectral variation is also observed even under ambient conditions by exposure of 4-ABT on Ag to volatile organic chemicals (VOCs) such as acetone and ammonia. Based on the potential-dependent SERS data, the effect of acetone appeared to correspond to an application of +0.15 V to the Ag substrate vs a saturated Ag/AgCl electrode, while the effect of ammonia corresponded to the application of -0.45 V to Ag. In chapter 4, as one of several attempts to explore the origin of the b2-type bands observable in the SERS of 4-ABT, the pH dependence has been investigated. Consulting the claim that those b2-type bands might be associated with a surface-induced photoreaction product such as 4,4′-DMAB, the pH dependence of the SERS spectral feature of 4,4′-DMAB was also examined. Distinct differences were observed in the SERS spectra of 4-ABT and 4,4′-DMAB. The SERS spectral feature of 4,4′-DMAB had virtually no dependence either on the excitation wavelength or on the kind of metal substrate or even on the solution pH. On the other hand, the SERS spectral pattern of 4-ABT displayed substantial changes, depending not only on the excitation wavelength and the kind of SERS substrates but also on the solution pH. It is presumed that when the amine group of 4-ABT is protonated at acidic pHs, the electron population in the benzene ring moiety decreases, resulting in the up-shift of the LUMO level of 4-ABT, as revealed by UV-vis spectra and from an ab initio calculation, thereby prohibiting the charge transfer resonance chemical enhancement. In chapter 5, the similarity and dissimilarity in the SERS of 4-ABT and 4,4′-DMAB, along with the SERS spectrum of their analog molecule 4,4′-dimercaptohydrazobenzene (4,4′-DMHAB) were carefully examined. Under ambient conditions, the SERS spectra of 4-ABT, 4,4′-DMAB, and 4,4′-DMHAB on Ag looked in fact comparable to one another, but the spectral dissimilarity was evidenced not only from the SERS spectra taken after treating the probing substrates with a borohydride solution but also from the potential-dependent SERS spectra. It was found that 4,4′-DMAB on Ag could convert to 4-ABT not only by contact with a 100 mM borohydride but also by lowering the potential below -1.0 V. The reverse reaction from 4-ABT on Ag to 4,4′-DMAB appeared insignificant electrochemically as well as photochemically. Furthermore, it was found that the conversion of 4,4′-DMAB to 4-ABT on Ag is a more feasible process upon irradiation with a 514.5-nm (not 632.8-nm) laser under ambient conditions. The SERS spectral pattern of 4,4-DMAB on Ag varied as a function of laser irradiation time, finally becoming the same as that of 4-ABT on Ag. The photoconversion of 4,4-DMAB upon 514.5-nm radiation was further confirmed not only by the coupling reaction with 4-cyanobenzoic acid to form amide bonds but also by the selective growth of calcium carbonate. After considering all the experiments conducted in the work, it is concluded that the appearance of the so-called b2-type bands in the SERS of 4-ABT must be attributed wholly to the involvement of the chemical enhancement mechanism, not due to the formation of 4,4′-DMAB.Contents Abstract (i) Contents (vi) List of Figures (x) List of Tables (xxi) List of Scheme (xxi) Chapter 1. General Concepts (1) 1. Raman Scattering Theory (2) 2. Raman Spectroscopy (5) 3. Surface-enhanced Raman Scattering (SERS) (7) 4. The Electromagnetic Theory of SERS (9) 5. SERS from Transition Metal (15) 6. The Chemical Enhancement Theory of SERS (18) References (24) Chapter 2. History of 4-Aminobenzenethiol (4-ABT) from SERS Field (28) 1. Introduction (29) 2. United Experimental Section (34) 3. References (40) Chapter 3. The SERS of 4-ABT on Pt and The Volatile Organic Chemicals (VOCs) Effects of 4-ABT on Ag (43) 3-1. SERS on Aggregates of Pt Nanoparticles with Definite Size (44) 1. Introduction (44) 2. Results and Discussion (46) 3. Summary and Conclusion (61) 4. References (62) 3-2. Effect of VOCs on SERS of 4-ABT on Ag: Comparison with the Potential Dependence (65) 1. Introduction (65) 2. Results and Discussion (68) 3. Summary and Conclusion (79) 4. References (81) Chapter 4. SERS of 4-ABT And 4,4-Dimercaptoazobenzene (4,4′-DMAB) on Ag And Au: pH Dependence of b2-Type Bands (84) 1. Introduction (85) 2. Results and Discussion (87) 3. Summary and Conclusion (97) 4. References (98) Chapter 5. Similarity and Dissimilarity in SERS of 4-ABT And Its Analog molecules (100) 5-1. Similarity And Dissimilarity in SERS of 4-ABT, 4,4-DMAB, And 4,4-Dimercaptohydrazobenzene (4,4-DMHAB) on Ag (101) 1. Introduction (101) 2. Results and Discussion (104) 3. Summary and Conclusion (118) 4. References (119) 5-2. Photoreduction of 4,4-DMAB on Ag Revealed by Raman Scattering Spectroscopy (122) 1. Introduction (122) 2. Results and Discussion (125) 3. Summary and Conclusion (138) 4. References (142) 5-3. Visible-Light Response of 4-ABT and 4,4-DMAB Silver Salts (145) 1. Introduction (145) 2. Results and Discussion (147) 3. Summary and Conclusion (160) 4. References (161) IV. Appendix 1. List of Publications (164) 2. List of Presentations (167) Abstract (Korean) (169)Docto

朝鮮後期 事大文書의 종류와 성격

Traditonal diplomacy places importance on proper forms and etiquette. Especially when envoys were representing the ruler of Joseon, proper form and etiquette became even more important; a great deal of meaning was attached to each action and every word. When these envoys went in place of the Joseon king, they represented him via documents on which were written characters expressing sadae (such as pyo(表), ju(奏), jon(箋), and ja(咨)); the envoys sent to Ching were represented by documents with the words jochik(詔勅) and jamun(咨文). Afterwards, the way of scripting these diplomatic documents became codified and efforts to continuously organize them ensued. In the late Joseon dynasty, the Joseon government felt an urgent need to take diplomatic documents it considered canon and systematically organize them, deal with problems that arose in documents used in Joseon-Ching relations and rectify them under the cultural policy of Joseon which were part of a publishing project, take the softening stance of the Ching towards Joseon into account while doing this, organize the records of how royal envoys dealt with the Ching, and improve the process of drafting documents expressing sadae so that errors could be corrected and not occur again

Improvement of methane production efficiency of microbial electrolysis cells using transition metal nanoparticles and granular activated carbon composites

Electromethanogenesis is a form of electrobiofuel production through a microbial electrolysis cell (MEC) where methane (CH4) is directly produced from an electrical current and carbondioxide (CO2) using a cathode. With the aim of maximizing methanogenesis in an MEC, this study utilized granular activated carbon (GAC) and a transition metal catalyst to fabricate nickel (Ni) nanoparticle (NP) loaded GAC (Ni-NP/GAC) composites and incorporated these into MECs. In this set-up, GAC acted as the main electrical conduit for direct interspecies electron transfer (DIET) between exoelectrogens and methanogenic electrotrophs, and the Ni NPs served as a catalyst to further improve microbe-to-GAC electron transfer. The Ni-NP/GAC-composites were prepared using two different methods (microwave irradiation and solution plasma ionization). The Ni NPs were determined to be well doped on the GAC surface according to a field emission scanning electron microscope (FE-SEM) and energy-dispersive X-ray (EDX) spectroscopy analysis. Adding GAC into MECs improved CH4 production. The Ni-NP/GAC composites prepared by solution plasma ionization showed the highest CH4 production (20.7mL), followed by the Ni-NP/GAC composite prepared by microwave irradiation (19.6mL), bare GAC (15.6mL), and GAC-free control (9.6mL). In the methanogenic MECs, 40.6% of CH4 was produced from an electrode reaction (i.e., reduction of CO2 to CH4), and the remaining 59.4% was generated by nonelectrode reactions. KEY WORDS: Microbial electrolysis cell 미생물전해전지; Solution plasma 솔루션 플라즈마; Direct interspecies electron transfer 종간전자직접전달; Electromethanogenesis 전기적메탄생산; Metal nanoparticle-activated carbon composite 금속 나노입자-활성탄 복합체제 1 장 서론 1 제 2 장 문헌연구 4 2.1 미생물전해전지 4 2.1.1 혐기성 소화의 기본원리 4 2.1.2 미생물전해전지의 기본원리 7 2.2 Direct interspecies electron transfer 9 2.2.1 Direct interspecies electron transfer의 기본원리 9 2.2.2 Direct interspecies electron transfer에 관여하는 미생물 11 2.2.3 Direct interspecies electron transfer의 최근 연구동향 14 2.3 Ni/Np-GAC 복합체 16 2.3.1 Microwave irradiation 16 2.3.2 Solution plasma 17 제 3 장 실험 재료 및 방법 20 3.1 실험 장치 20 3.1.1 미생물전해전지 구성 20 3.1.2 Ni/Np-GAC 복합체 제작 22 3.2 운전조건 24 3.3 분석과 계산 26 3.3.1 미생물전해전지의 메탄가스 생산량 26 3.3.2 복합체 증착효율 평가 27 제 4 장 실험 결과 및 고찰 28 4.1 Ni/Np-GAC 복합체의 특성평가 28 4.1.1 Ni/Np-GAC 복합체의 표면특성 및 니켈 부착량 계산 28 4.2 미생물전해전지의 성능평가 31 4.2.1 미생물전해전지의 메탄가스 생산량 평가 31 4.2.2 미생물전해전지에서 발생하는 메탄의 기원 34 제 5 장 결론 38 감사의글 40 참고문헌 41Maste

공동주택 온수분할공급 난방방식의 경제성 평가에 관한 연구

학위논문(석사)--서울대학교 대학원 :건축학과,1998.Maste

Surface enrichment of Ag atoms in AuAg alloy nanoparticle revealed by surface enhanced raman scattering spectroscopy

Thesis(master`s)--서울대학교 대학원 :화학부 물리화학전공,2005.Maste

사람 기도점액 상피세포에서 베르베린이 Interleukin-1β 로 인한 MUC5AC 유전자 발현에 미치는 영향

Dept. of Medicine/석사Berberine is a bitter-tasting, yellow plant alkaloid with a long history ofmedicinal use in Chinese and Ayurvedic medicine. There is some evidence tosupport its use in the treatment of heart failure, malaria, diabetes, glaucoma,hypercholesterolemia, diarrhea, trachoma, and leishmaniasis. Traditionally, it hasbeen used as anti-fungal, anti-inflammatory, anti-viral agents, and also inrespiratory disorders. However, there is no evidence that berberine can suppressmucin secretion in human airway. Therefore, the aim of this study was toinvestigate whether berberine suppresses IL-1β-induced MUC5AC gene expressionin human airway epithelial cells and, if so, to examined which mitogen-activatedprotein kinases (MAPKs) were related to MUC5AC gene suppression. MUC5ACmRNA and protein were measured using reverse transcription-polymerase chainreaction (RT-PCR), real-time PCR, and western blot analysis in culturedNCI-H292 human airway epithelial cells. Extracellular signal-regulated kinase(ERK) and p38 MAPK protein levels were analyzed by Western blot. When thecells were pretreated with 25 μM of berberine, expression of IL-1β-inducedMUC5AC mRNA and protein was significantly suppressed compared to the controlgroup. MAPKs proteins were determined by Western blot analysis afterpretreatment with 25 μM berberine. Berberine suppressed phosphorylation ofextracellular signal regulated kinase (ERK) and p38 MAPK, but there was nochange in the expression of α-tubuline. Suppression of IL-1β-induced MUC5ACmRNA was also observed in cells pretreated with ERK- or p38 MAPK-specificinhibitors, suggesting that berberine suppression of IL-1β- induced MUC5ACmRNA operated via the ERK- and p38 MAPK-dependent pathways. Berberinesuppresses IL-1β-induced MUC5AC gene expression in human airway epithelialcells via the ERK- and p38 MAPK-dependent pathways. Therefore, berberine maybe considered a possible anti-hypersecretory agent.ope