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BURP域家族是植物特有的一個蛋白家族，結構多樣，共同點是在羧基端都有一個保守的BURP域。迄今為止，關於BURP域家族成員的功能及細胞定位的研究非常有限。部分RD22-like的亞家族成員由於顯示出受非生物脅迫而誘導表達的特性，因此被認為功能可能與非生物脅迫回應相關。本研究對克隆到的一個受非生物脅迫誘導表達的大豆基因(GmRD22)進行了生物進化分析，并詳細分析了其在不同的大豆品種以及不同非生物脅迫下的表達模式，揭示了其表達豐度與大豆的抗非生物脅迫能力有關，並且使用不同的轉基因系統(細胞水準跟植物水準)揭示了其過量表達有助於減輕非生物脅迫對植物造成的影響。研究利用GFP融合蛋白追蹤技術和免疫電鏡技術揭示GmRD22蛋白定位於細胞壁，其中BURP域對於GmRD22定位于細胞壁起到關鍵作用。研究也揭示了GmRD22能夠與細胞外的一種過氧化物酶GmPer1相互作用，GmRD22在轉基因擬南芥和轉基因水稻中的過量表達能夠顯著提高脅迫條件下轉基因植株中木質素的含量。我們認為GmRD22通過與細胞壁過氧化物酶的相互作用來提高植物在脅迫條件下細胞壁的完整性從而增強植株的抗性。 / The BURP-domain protein family comprises a diverse group of plant-specific proteins that share a conserved BURP domain at the C terminus. However, there have been only limited studies on the functions and subcellular localization of these proteins. Members of the RD22-like subfamily are postulated to associate with stress responses due to the stress-inducible nature of some RD22-like genes. In this report, different expression patterns of a stress-inducible RD22-like protein from soybean (GmRD22) either in different soybean species or under different osmotic stress conditions were analyzed, different transgenic systems (cells and in planta) were used to show that the ectopic expression of GmRD22 can alleviate salinity and osmotic stress. The detailed microscopic studies were also performed using both fusion proteins and immuno-electron microscopic techniques to demonstrate the apoplast localization of GmRD22, for which the BURP domain is a critical determinant of the subcellular localization. The apoplastic GmRD22 interacts with a cell wall peroxidase and the ectopic expression of GmRD22 in both transgenic A. thaliana and transgenic rice resulted in increased lignin production when subjected to salinity stress. It is possible that GmRD22 regulates cell wall peroxidase and hence strengthens cell wall integrity under osmotic stress conditions. / Detailed summary in vernacular field only. / Wang, Hongmei. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 124-136). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstract --- p.i / Acknowledgements --- p.iii / Table of contents --- p.v / List of tables --- p.x / List of figures --- p.xi / General abbreviations --- p.xiii / Chemical abbreviations --- p.xv / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Abiotic stress in the world --- p.2 / Chapter 1.2 --- The advances of plant abiotic stress resistance mechanisms --- p.5 / Chapter 1.2.1 --- Sensor of salt stress --- p.7 / Chapter 1.2.2 --- Reestablishment of ionic homeostasis --- p.9 / Chapter 1.2.3 --- Osmoregulation by compatible osmolytes --- p.11 / Chapter 1.2.4 --- Oxidative stress management --- p.12 / Chapter 1.2.5 --- Transcription regulation of gene expression in osmotic stress --- p.14 / Chapter 1.3 --- The BURP-domain protein family --- p.19 / Chapter 1.3.1 --- Introduction of BURP-domain protein family --- p.19 / Chapter 1.3.2 --- Advances of BURP-domain protein studies --- p.20 / Chapter 1.3.3 --- The BURP-domain protein and osmotic stress --- p.21 / Chapter 1.4 --- Background information of this project --- p.22 / Chapter 1.5 --- Hypothesis and objectives --- p.25 / Chapter Chapter 2 --- Materials and Methods --- p.26 / Chapter 2.1 --- Bacterial strains, vectors and plasmids, cell lines and plant materials --- p.27 / Chapter 2.2 --- Chemicals and reagents --- p.32 / Chapter 2.3 --- Primers used in this study --- p.35 / Chapter 2.4 --- Molecular cloning of GmRD22 --- p.38 / Chapter 2.5 --- DNA and RNA extraction and Northern blot --- p.40 / Chapter 2.5.1 --- DNA and plasmid extraction --- p.40 / Chapter 2.5.2 --- RNA extraction from plant --- p.41 / Chapter 2.5.3 --- Generation of DIG-labeled PCR probe --- p.41 / Chapter 2.5.4 --- Northern blot --- p.43 / Chapter 2.6 --- Reverse transcription and Real-time analysis --- p.44 / Chapter 2.7 --- Phylogenetic analysis --- p.45 / Chapter 2.8 --- Basic molecular techniques --- p.46 / Chapter 2.8.1 --- Recombinant DNA --- p.46 / Chapter 2.8.2 --- Transformation of E. coli competent cells --- p.46 / Chapter 2.8.3 --- Transformation of A. tumefacien competent cells --- p.47 / Chapter 2.8.4 --- Gel electrophoresis --- p.48 / Chapter 2.8.5 --- Sequencing --- p.48 / Chapter 2.9 --- Establishment of transgenic models --- p.49 / Chapter 2.9.1 --- Establishment of transgenic BY-2 cell --- p.49 / Chapter 2.9.2 --- Establishment of transgenic A. thaliana --- p.50 / Chapter 2.9.3 --- Establishment of transgenic rice --- p.51 / Chapter 2.10 --- Cell viability assay under osmotic stress treatment --- p.51 / Chapter 2.11 --- Root elongation assay of transgenic A. thaliana --- p.52 / Chapter 2.12 --- Osmotic stresses treatment of transgenic rice lines --- p.52 / Chapter 2.13 --- Protein expression, production of antibodies and Western blot --- p.53 / Chapter 2.14 --- Subcellular localization of fusion protein by confocal microscopic study --- p.55 / Chapter 2.15 --- Electron microscopic study --- p.56 / Chapter 2.16 --- Immunoprecipitation and mass spectrometry --- p.57 / Chapter 2.17 --- Cell wall components analysis --- p.60 / Chapter 2.18 --- Statistical analysis --- p.61 / Chapter Chapter 3 --- Results --- p.62 / Chapter 3.1 --- GmRD22 gene --- p.63 / Chapter 3.1.1 --- GmRD22 encodes a BURP-domain protein in soybean --- p.63 / Chapter 3.1.2 --- Phylogenetic analysis of GmRD22 --- p.65 / Chapter 3.2 --- GmRD22 gene expression --- p.73 / Chapter 3.2.1 --- GmRD22 shows a biphasic induction by salinity stress and ABA treatment --- p.73 / Chapter 3.2.2 --- GmRD22 is also inducible by osmotic stress --- p.76 / Chapter 3.2.3 --- GmRD22 shows stronger and faster induction in WF 7 than Union --- p.76 / Chapter 3.3 --- Functional study --- p.78 / Chapter 3.3.1 --- Construction of GmRD22 transformants --- p.78 / Chapter 3.3.2 --- Ectopic expression of GmRD22 improve osmotic stresses tolerance in transgenic BY-2 cells --- p.80 / Chapter 3.3.3 --- Ectopic expression of GmRD22 alleviates osmotic stresses in transgenic A. thaliana --- p.83 / Chapter 3.3.4 --- Ectopic expression of GmRD22 alleviates osmotic stresses in transgenic rice --- p.86 / Chapter 3.4 --- GmRD22 is an apoplastic protein --- p.90 / Chapter 3.4.1 --- Western blot analysis in different soybean extracts --- p.90 / Chapter 3.4.2 --- Subcellular localization of GmRD22-GFP fusion protein in onion epidermal and A. thaliana root system --- p.93 / Chapter 3.4.3 --- GmRD22 localization in native soybean --- p.96 / Chapter 3.5 --- BURP domain is essential for the subcellular localization --- p.99 / Chapter 3.6 --- GmRD22 interacts with a putative apoplastic peroxidase --- p.103 / Chapter 3.6.1 --- Identification of GmRD22 interacting protein --- p.103 / Chapter 3.6.2 --- GmPer1 is a putative extracellular class III peroxidase --- p.107 / Chapter 3.6.3 --- Overexpression of GmRD22 affected lignin metabolism in transgenic rice and A. thaliana under salinity stress --- p.109 / Chapter 3.6.4 --- GmPer1 homologues increased expression under salinity stress --- p.113 / Chapter Chapter 4 --- Discussion and Conclusion --- p.115 / Chapter 4.1 --- GmRD22 as a member of RD22-like subfamily --- p.116 / Chapter 4.2 --- Induction mechanism of GmRD22 expression is related to ABA --- p.117 / Chapter 4.3 --- Biological function of GmRD22 providing protective effect under osmotic stress --- p.118 / Chapter 4.4 --- The BURP domain of GmRD22 plays a key role in its apoplastic targeting --- p.119 / Chapter 4.5 --- The interaction between GmRD22 and apoplastic peroxidase provides the clue for the mechanism of enhanced osmotic stress tolerance in GmRD22 transgenic plants --- p.120 / Chapter 4.6 --- Conclusion --- p.123 / References --- p.124 / Chapter Appendix I --- Restriction and modifying enzymes --- p.137 / Chapter Appendix II --- Chemicals --- p.138 / Chapter Appendix III --- Buffer, solution, gel and medium formulation --- p.143 / Chapter Appendix IV --- Equipment and facilities --- p.146

The acidities of 37 amino-substituted heterocyclic compounds have been determined using measurements of degree of ionization in DMSO/ water/0.011 M hydroxide ion and recently developed extrapolative procedures which are based on the Bunnett-Olseh (B.O.) and the Marziano-Cimino-Passerini (M.C.P.) methods. The compounds studied include 19 aminopyridines and pyrimidines and 18 derivatives of the biologically important nucleotide bases, cytosine, adenine and guanine. The UV/vis spectra of the neutral and anionic forms of the amino-pyridines and pyrimidines are well separated so that in evaluating the ionization ratios, changes of the spectra with medium composition were accounted for by measuring at the wavelength of maximum anionic absorption in each solution and by assuming that eA- and eHA vary linearly with HN . For the majority of the nucleotide derivatives, the neutral and anionic spectra were closely overlapping although different in shape. The ionization ratios were best evaluated by using the area under the spectral curve; spectral changes with solvent composition were accounted for by an adaptation of the method described above. Ionization ratios evaluated by the area method agreed well with those calculated by other methods as long as the anionic area was at least one and one-half times as great as the neutral area (or vice versa). The aminopyrimidines and purines define a new acidity function Hp . This function covers the range from water to 87.6 mole % DMSO and was established using 15 aminopyrimidines and purines. When Hp plotted against mole % DMSO, it rises less steeply than HN. This has been attributed to less extensive derealization of charge in the aminopyrimidine anion relative to that of an aniline (usually a nitroaniline) ionizing at the same solvent composition. The B.O. pKHA values of unsubstituted 2- and 4-aminopyridine, 2- and 4-aminopyrimidine and 2-amino-s-triazine, ranging from 23.50 to 14.91 are well-correlated by a Hammett plot using a values recently established for aza substituents and assuming the additivity of aza substituent effects, p. 4.99. The B.O. pKHA values of five substituted anilines, ranging from 25.50 to 23.13, fall close to this plot. All ten compounds are accommodated by a straight line, p value 5.10, which suggests that the aminoheterocycles may be considered to be aza-substituted anilines. It appears that the sensitivity of aniline and diphenylamine acidity to substituent effects is greater than previously believed. The findings in this work suggest that transmission of substituent effects through a heterocyclic and a benzene nucleus are equal and that an aza group may be regarded as a normal ring substituent. From the acidities of substituted aminopyridines and pyrimidines it appears that, to a first approximation, aza groups do not perturb the effects of other substituents on the same nucleus, although there may be a small resonance interaction between a +R group, such as chloro, and an aza group lying para to it. The same conclusion was reached from examination of the basicities of these compounds. / Science, Faculty of / Chemistry, Department of / Graduate

by So Mei Po. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 105-111). / Abstracts in English and Chinese. / Title Page --- p.i / Table of Contents --- p.ii / List of Tables --- p.v / List of Figures --- p.vii / Abbreviations --- p.xi / Acknowledgements --- p.xii / Abstract --- p.xiii / Chapter CHAPTER ONE --- INTRODUCTION / Chapter 1.1 --- Chiral Recognition Detected by Mass Spectrometry --- p.1 / Chapter 1.2 --- Fast Atom Bombardment Mass Spectrometry --- p.7 / Chapter 1.2.1 --- Desorption/Ionization in FAB --- p.7 / Chapter 1.2.1.1 --- Matrix --- p.8 / Chapter 1.2.1.2 --- Atom/Ion Guns --- p.9 / Chapter 1.3 --- Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry --- p.9 / Chapter 1.3.1 --- Development of Matrix-Assisted Laser Desorption/Ionization --- p.10 / Chapter 1.3.2 --- Matrix-Assisted Laser Desorption/Ionization --- p.11 / Chapter 1.3.2.1 --- The Matrix --- p.12 / Chapter 1.3.2.2 --- Mechanisms of Ion Formation --- p.12 / Chapter 1.3.2.2.1 --- Desorption --- p.13 / Chapter 1.3.2.2.2 --- Ionization --- p.13 / Chapter 1.4 --- Blackbody Infrared Radiative Dissociation (BIRD) --- p.14 / Chapter 1.4.1 --- Photodissociation --- p.15 / Chapter 1.4.2 --- Blackbody Infrared Radiative Dissociation --- p.15 / Chapter 1.5 --- Outline of the Present Work --- p.18 / Chapter CHAPTER TWO --- INSTRUMENTATION AND EXPERIMENTAL / Chapter 2.1 --- Time-of-flight Mass Spectrometry --- p.19 / Chapter 2.1.1 --- Delayed Extraction --- p.23 / Chapter 2.1.2 --- Instrumentation --- p.24 / Chapter 2.1.2.1 --- Laser System --- p.24 / Chapter 2.1.2.2 --- Ion Source --- p.26 / Chapter 2.1.2.3 --- Reflector --- p.27 / Chapter 2.1.2.4 --- Detector --- p.27 / Chapter 2.1.2.5 --- Data Acquisition and Computer Control --- p.27 / Chapter 2.2 --- Fourier Transform Ion cyclotron Resonance Mass Spectrometry --- p.28 / Chapter 2.2.1 --- Ion Source --- p.29 / Chapter 2.2.1.1 --- Fast Atom Bombardment Mass spectrometry (FABMS) --- p.29 / Chapter 2.2.2 --- Electrostatic Ion Focusing System --- p.31 / Chapter 2.2.3 --- ICR Analyzer Cell and Magnet --- p.34 / Chapter 2.2.4 --- Data Acquisition and Handling system --- p.38 / Chapter 2.3 --- Experimental --- p.38 / Chapter 2.3.1 --- Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry --- p.38 / Chapter 2.3.1.1 --- Sample Preparation --- p.38 / Chapter 2.3.1.2 --- Mass Spectrometric Analysis --- p.39 / Chapter 2.3.2 --- Fast Atom Bombardment Mass Spectrometry --- p.39 / Chapter 2.3.2.1 --- Sample preparation --- p.39 / Chapter 2.3.2.2 --- Blackbody Infrared Radiative Dissociation --- p.39 / Chapter CHAPTER THREE --- HOST-GUEST COMPLEXES DETECTED BY MATRIX- ASSISTED LASER DESORPTION/IONIZATION MASS SPECTROMETRY / Chapter 3.1 --- Introduction --- p.42 / Chapter 3.2 --- Sample Preparation --- p.45 / Chapter 3.3 --- Results and Discussions --- p.49 / Chapter 3.3.1 --- Cyclodextrins - Cyclic Maltooligosaccharides --- p.49 / Chapter 3.3.2 --- Maltooligosaccharide --- p.55 / Chapter 3.4 --- Conclusions --- p.64 / Chapter CHAPTER FOUR --- DIFFERENTIATION OF ENANTIOMERS USING MALDI-TOF-MS / Chapter 4.1 --- Introduction --- p.65 / Chapter 4.2 --- Experimental --- p.67 / Chapter 4.2.1 --- MALDI-MS Studies --- p.67 / Chapter 4.2.2 --- Calculation --- p.68 / Chapter 4.3 --- Results and Discussions --- p.69 / Chapter 4.3.1 --- MALDI-MS Studies --- p.69 / Chapter 4.3.2 --- Calculations --- p.74 / Chapter 4.4 --- Conclusion --- p.81 / Chapter CHAPTER FIVE --- BLACKBODY INFRARED RADIATION DISSOCIATION (BIRD) OF DIASTEREOCOMPLEXES / Chapter 5.1 --- Introduction --- p.86 / Chapter 5.2 --- Experimental --- p.88 / Chapter 5.3 --- Result and Discussion --- p.89 / Chapter 5.3.1 --- BIRD of Amino-acid/Cyclodextrin complexes --- p.89 / Chapter 5.3.2 --- BIRD of Proton-bound Amino Acid Dimers and Amino Acid/dipeptide Dimers --- p.91 / Chapter 5.4 --- Conclusion --- p.102 / Chapter CHAPTER SIX --- CONCLUSIONS AND FURTHER WORKS / Chapter 6.1 --- Conclusions --- p.103 / Chapter 6.2 --- Further Works --- p.104 / REFERENCES --- p.105

by Ho, Wai Fun. / Thesis (M.Sc.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 79-87). / LIST OF TABLES --- p.iv / LIST OF FIGURES --- p.vi / ACKNOWLEDGEMENTS --- p.vii / ABSTRACT --- p.viii / Chapter 1. --- INTRODUCTION --- p.1 / Chapter 1.1 --- METABOLIC DERANGEMENTS AND CACHEXIA IN CANCER --- p.1 / Chapter 1.2 --- PROTEIN METABOLISM IN MALIGNANCY --- p.4 / Chapter 1.3 --- REVIEW OF REPORTS ON AMINO ACID DISTURBANCES IN MALIGNANCY --- p.5 / Chapter 1.4 --- AMINO ACID ANALYSIS BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY --- p.10 / Chapter 1.4.1 --- Amino Acid Analysis by Ion-Exchange HPLC --- p.11 / Chapter 1.4.2 --- Amino Acid Analysis by Reversed-Phase HPLC --- p.13 / Chapter 1.4.3 --- Derivatizing Agents --- p.15 / Chapter 1.5 --- CHOICE OF CANCER PATIENTS AND METHODOLOGY FOR THIS STUDY --- p.19 / Chapter 1.5.1 --- Choice of Cancer Patients --- p.19 / Chapter 1.5.2 --- Methodology Chosen and Its Principle --- p.20 / Chapter 2. --- OBJECTIVES --- p.23 / Chapter 3. --- MATERIALS AND METHODS --- p.24 / Chapter 3.1 --- STUDY SUBJECTS --- p.24 / Chapter 3.1.1 --- Patients --- p.24 / Chapter 3.1.2 --- Control Subjects --- p.25 / Chapter 3.2 --- CLINICAL FEATURES --- p.25 / Chapter 3.3 --- BLOOD COLLECTION --- p.25 / Chapter 3.4 --- GENERAL BIOCHEMICAL TESTS --- p.26 / Chapter 3.5 --- PLASMA AMINO ACID ANALYSIS BY HPLC --- p.26 / Chapter 3.5.1 --- Apparatus --- p.26 / Chapter 3.5.2 --- Reagents --- p.27 / Chapter 3.5.3 --- Reagent Preparation --- p.28 / Chapter 3.5.3.1 --- Mobile phase --- p.28 / Chapter 3.5.3.2 --- Derivatizing reagent --- p.29 / Chapter 3.5.4 --- Standard Preparation --- p.29 / Chapter 3.5.4.1 --- Internal standard solution --- p.29 / Chapter 3.5.4.2 --- Composite standard solution --- p.30 / Chapter 3.5.4.3 --- Composite standard-internal standard mixture --- p.32 / Chapter 3.5.5 --- Sample Preparation --- p.32 / Chapter 3.5.5.1 --- Protein removal --- p.32 / Chapter 3.5.5.2 --- Addition of internal standard --- p.32 / Chapter 3.5.6 --- Preparation of Samples for the WISP Sample Processor --- p.33 / Chapter 3.5.7 --- Sample Queue for the WISP Sample Processor --- p.33 / Chapter 3.5.8 --- Automated Derivatization Procedure --- p.36 / Chapter 3.5.9 --- Chromatographic Conditions --- p.36 / Chapter 3.6 --- STATISTICAL STUDIES --- p.38 / Chapter 4. --- RESULTS --- p.40 / Chapter 4.1 --- ANALYTICAL PERFORMANCES --- p.40 / Chapter 4.1.1 --- Chromatograms --- p.40 / Chapter 4.1.2 --- Precision --- p.47 / Chapter 4.1.3 --- Linearity --- p.47 / Chapter 4.1.4 --- Analytical Recovery --- p.51 / Chapter 4.2 --- DATA DISTRIBUTION STUDIES --- p.53 / Chapter 4.3 --- PATIENTS' ANTHROPOMETRIC DATA AND BLOOD BIOCHEMISTRY --- p.55 / Chapter 4.4 --- FREE PLASMA AMINO ACID CONCENTRATIONS IN NORMAL CONTROLS --- p.59 / Chapter 4.5 --- FREE PLASMA AMINO ACID CONCENTRATIONS IN CANCER PATIENTS --- p.59 / Chapter 5. --- DISCUSSION --- p.68 / Chapter 5.1 --- METHOD ESTABLISHMENT --- p.68 / Chapter 5.2 --- NORMAL CONTROLS --- p.68 / Chapter 5.3 --- CANCER PATIENTS --- p.71 / Chapter 5.3.1 --- Nasopharyngeal Cancer --- p.71 / Chapter 5.3.2 --- Lung Cancer --- p.71 / Chapter 5.3.3 --- Breast Cancer --- p.72 / Chapter 5.3.4 --- Colorectal Cancer --- p.74 / Chapter 5.4 --- SUMMARY OF THE PLASMA AMINO ACID PROFILES IN CANCER --- p.75 / Chapter 5.5 --- FURTHER STUDIES --- p.76 / Chapter 6. --- CONCLUSION --- p.78 / Chapter 7. --- REFERENCES --- p.79

Poon Wai Mei Emily. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 74-81). / Abstracts in English and Chinese. / Chapter Chapter 1: --- Introduction --- p.1 / Chapter 1.1. --- Importance of amino acids --- p.1 / Chapter 1.1.1. --- Clinical samples --- p.1 / Chapter 1.1.2. --- Food samples --- p.2 / Chapter 1.2. --- Reviews of amino acid analysis --- p.6 / Chapter 1.2.1. --- Ion-exchange chromatography --- p.6 / Chapter 1.2.2. --- Gas chromatography --- p.6 / Chapter 1.2.3. --- Thin layer chromatography --- p.8 / Chapter 1.2.4. --- Flow injection analysis --- p.8 / Chapter 1.2.5. --- Liquid chromatography --- p.9 / Chapter 1.2.6. --- Capillary electrophoresis --- p.10 / Chapter 1.2.7. --- Methods of detecting amino acid without derivatization --- p.11 / Chapter 1.3. --- Determination of amino acids by reversed-phase ion-pair chromatography --- p.12 / Chapter 1.4. --- The objectives of the study --- p.15 / Chapter Chapter 2: --- Experimental --- p.16 / Chapter 2.1. --- Materials --- p.16 / Chapter 2.2. --- Apparatus --- p.16 / Chapter 2.3. --- Samples --- p.16 / Chapter 2.4. --- Procedures --- p.17 / Chapter 2.4.1. --- Preparation of amino acid standard solution (stock solutions) --- p.17 / Chapter 2.4.2. --- Method development --- p.17 / Chapter 2.4.3. --- Samples preparation --- p.18 / Chapter 2.4.4. --- Preparation of Dowex column --- p.18 / Chapter 2.4.5. --- Extraction of amino acids from samples --- p.19 / Chapter 2.4.6. --- Recovery test --- p.20 / Chapter Chapter 3: --- Results and Discussions --- p.21 / Chapter 3.1. --- Optimization --- p.21 / Chapter 3.1.1. --- pH --- p.21 / Chapter 3.1.2. --- Ion-interacting reagent --- p.22 / Chapter 3.1.3. --- Organic solvent --- p.29 / Chapter 3.1.4. --- Temperature --- p.34 / Chapter 3.1.5. --- Chromatographic conditions --- p.36 / Chapter 3.2. --- Application --- p.45 / Chapter 3.2.1. --- Precision of injection --- p.45 / Chapter 3.2.2. --- Accuracy of the method --- p.46 / Chapter 3.2.3. --- The concentration of amino acids in food samples --- p.50 / Chapter 3.2.3.1. --- Citrus fruits --- p.50 / Chapter 3.2.3.2. --- Orange juice drinks --- p.60 / Chapter 3.2.3.3. --- Chinese honey --- p.65 / Chapter 3.2.3.4. --- New Zealand honey --- p.67 / Chapter 3.2.3.5. --- Energy drinks --- p.70 / Chapter Chapter 4 : --- Conclusion --- p.72 / Chapter Chapter 5 : --- Bibliographies --- p.74 / Chapter 6. --- Appendices --- p.82 / Chapter 6.1. --- Table 1 : Ingredients of orange juice drinks --- p.82 / Chapter 6.2. --- Table 2 : Honey samples --- p.83 / Chapter 6.3. --- Table 3 : Ingredients of energy drinks --- p.83

Abstract not available

The electrochemical detector provides a promising detection mode for capillary electrophoresis (CE) due to its excellent sensitivity, good portability, high selectivity, easy miniaturization, low capital and running cost. To widen its scope for determining trace analytes in complex samples, three dual-electrode detectors were fabricated to enable the determination of electro-inactive analytes, to assess co-eluted peaks and to give a large enhancement of the detection sensitivity by modifying electrode surface using multi-walled carbon nanotubes (MWNTs). To determine trace non-electroactive amino acids present in human tears, a serial dual-electrode detector was developed using an upstream on-capillary Pt film electrode to oxidize bromide to bromine at +1.0 V and a downstream Pt disk electrode to detect the residual bromine at +0.2 V after their reaction with amino acids eluted out from the separation capillary. The bromide reagent was introduced after CE separation by a newly designed coaxial post-column reactor fabricated onto the PMMA chip. Using optimized CE buffer containing 20 mM borate, 20 mM SDS at pH 9.8, L-glutamine, L-alanine and taurine were baseline separated with detection limits ranging from 0.56-0.65 μM and a working range of 2-200 μM for L-glutamine and of 2-300 μM for both L-alanine and taurine. Method reliability was established by close to 100% recoveries for spiked amino acids and good agreement between the measured and the literature reported amino acid concentrations in tears. For the determination of polyphenols in wine, a microchip-CE device was fabricated with a dual-opposite carbon fiber microelectrode operated in a parallel mode to assess peak purity. Under optimized conditions, (+)-catechin, trans-resveratrol, quercetin, (-)-epicatechin and gallic acid were baseline separated within 16 min with detection limits ranging from 0.031- 0.21 mg/L and repeatability of 2.0-3.3 % (n=5). The use of an opposite dual-electrode enables the simultaneous determination of peaks and measurement of their current ratios at +0.8 V and +1.0 V vs Ag/AgCl. The capability of using current ratio to identify the presence of co-migrating impurities was demonstrated in a mixed standard solution with overlapping (+)-catechin and (-)-epicatechin peaks and in a commercial red wine with interfering impurities. Matching of both the migration time and the current ratio reduce false positive and validate polyphenol quantitation in red wine. Lastly, a dual-opposite MWNTs modified carbon fiber microelectrode (CFME) was developed to determine the biomarkers (4-nitrophenol, 4-nitrophenyl-glucuronide and 4-nitrophenyl-sulfate) needed to assess exposure to methyl parathion. Use of the MWNTs modified CFME showed a much higher sensitivity than bare CFME, with a detection limit of 0.46 μM for 4-nitrophenol. Baseline separation of all three biomarkers was obtained within 31 min by a 45 cm long capillary under 12 kV in a 20 mM phosphate buffer at pH 7.0. The method developed was successfully utilized to determine low levels of biomarkers in human urine without using complex pretreatment steps and delivered recoveries ranging from 95.3 - 97.3% and RSDs within 5.8% (n=3). Using a parallel dual-electrode detector was shown to deliver reliable results with matching current ratios and comparable migration time to those obtained from biomarker standards. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

Diss. (sammanfattning) Stockholm : Karol. inst., 2001. / Härtill 5 uppsatser.

Thesis (Ph.D)--Biology, Georgia Institute of Technology, 2008. / Committee Chair: Skolnick, Jeffrey; Committee Member: Fernandez, Facundo; Committee Member: Jordan, King; Committee Member: McDonald, John; Committee Member: Sherrill, David. Part of the SMARTech Electronic Thesis and Dissertation Collection.