近十年間，離子液體在生物催化和蛋白質化學方面的廣泛應用引起了鑒定蛋白質在離子液體中特性的研究興趣。本研究以古菌Pyrococcus horikoshii的酰基磷酸酶acylphosphatase (PhAcP) 和50% (v/v) 離子液體1-乙基-3-甲基咪唑四氟硼酸鹽 ([EMIM][BF₄]) 作為研究模型，首次利用多維核磁共振譜對蛋白質在離子液體中的結構和穩定性作高解析度的分析。我們首先通過蛋白質主鏈共振歸屬，得出PhAcP每個被歸屬的胺基酸在50% (v/v) [EMIM][BF₄] 中¹³C[superscript α]、¹³C[superscript β]、¹³CO、¹⁵N、H[superscript N]和H[superscript α]原子的化學位移。¹³C的化學位移相對無序纏捲狀態的¹³C化學位移的偏差分析 (¹³C secondary shift)，以及二級結構之間的nuclear Overhauser effect (NOE) 連接顯示PhAcP在50% (v/v) [EMIM][BF₄] 中的二級結構與PhAcP的自然結構大致相同，其三級結構亦無顯著變化。此外，我們以二維的¹H-¹⁵N HSQC實驗觀察在318K、328K和338K這三個溫度下的硫氰酸胍 (GdnSCN) 誘導蛋白質變性，發現同一溫度下無論50% (v/v) [EMIM][BF₄]是否存在，PhAcP的變性曲線都互相重疊，得到的 [GdnSCN]₁[subscript /]₂值也相同，由此可推斷50% (v/v) [EMIM][BF₄] 對PhAcP的穩定性沒有影響。 / The extensive application of ionic liquid in biocatalysis and protein chemistry in the past decade arouses interest in the characterization of protein behavior in ionic liquid. This study demonstrates the use of multi-dimensional nuclear magnetic resonance (NMR) spectroscopy to investigate the structure and conformational stability of protein in ionic liquid at a high resolution for the first time, with Pyrococcus horikoshii acylphosphatase (PhAcP) and 50% (v/v) 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF₄]) as a study model. The backbone amide resonances of PhAcP in 50% (v/v) [EMIM][BF₄] were assigned in order to obtain the chemical shifts of ¹³C[superscript α], ¹³C[superscript β], ¹³CO, ¹⁵N, HN and H[superscript α] of each assigned residue. The estimation of secondary structure by the ¹³C secondary shift analysis and the nuclear Overhauser effect (NOE) connectivities observed within secondary structures together suggest that PhAcP has secondary structures arranged in native-like topology and there is no major alteration in the tertiary structure in 50% (v/v) [EMIM][BF₄]. Guanidine thiocyanate (GdnSCN)-induced denaturation was performed at 318K, 328K and 338K and monitored by 2D ¹H-¹⁵N HSQC experiments to study the conformational stability of PhAcP in 50% (v/v) [EMIM][BF₄]. The overlapping denaturation curves and consistent [GdnSCN]₁[subscript /]₂ values obtained at each temperature indicate no observable trend of stability alteration. / Detailed summary in vernacular field only. / Lee, Tsz Ying. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 57-63). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese. / Abstract --- p.i / 摘要 --- p.ii / Acknowledgements --- p.iii / Contents --- p.iv / Abbreviations --- p.vii / List of Figures --- p.viii / List of Tables --- p.ix / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Introduction to ionic liquid --- p.1 / Chapter 1.1.1 --- Ionic liquid as reaction medium, co-solvent and additive in biocatalysis and protein chemistry --- p.1 / Chapter 1.1.2 --- The impact of ionic liquid on protein structure and stability is poorly understood --- p.3 / Chapter 1.2 --- PhAcP in [EMIM][BF₄] as a model to study the structure and stability of protein in ionic liquid by NMR spectroscopy --- p.6 / Chapter 1.2.1 --- The application of [EMIM][BF₄] with protein --- p.6 / Chapter 1.2.2 --- The background of PhAcP --- p.9 / Chapter 1.2.3 --- Overview of the study --- p.10 / Chapter Chapter 2 --- Materials and Methods --- p.12 / Chapter 2.1 --- Expression and purification of PhAcP --- p.12 / Chapter 2.1.1 --- Expression of PhAcP in Escherichia coli system --- p.12 / Chapter 2.1.2 --- Purification of PhAcP --- p.14 / Chapter 2.2 --- Solubility determination --- p.15 / Chapter 2.3 --- NMR experiments --- p.17 / Chapter 2.3.1 --- General procedures and sample preparation --- p.17 / Chapter 2.3.2 --- ¹H-¹⁵N HSQC spectra in various concentrations of [EMIM][BF₄] --- p.18 / Chapter 2.3.3 --- Structural characterization --- p.18 / Chapter 2.3.4 --- Stability characterization --- p.19 / Chapter Chapter 3 --- Results --- p.21 / Chapter 3.1 --- Can the solubility of PhAcP in [EMIM][BF₄] reach the millimolar range required for NMR study? --- p.21 / Chapter 3.2 --- Determination of the [EMIM][BF₄] concentration for a feasible NMR study --- p.23 / Chapter 3.3 --- Backbone resonance assignment of PhAcP in 50% (v/v) [EMIM][BF₄] --- p.26 / Chapter 3.4 --- Structural characterization of PhAcP in 50% (v/v) [EMIM][BF₄] --- p.29 / Chapter 3.4.1 --- Secondary structure estimation by ¹³C secondary shifts --- p.29 / Chapter 3.4.2 --- NOE connectivities within secondary structures --- p.35 / Chapter 3.5 --- Characterization of the conformational stability of PhAcP in 50% (v/v) [EMIM][BF₄] by guanidine thiocyanate-induced denaturation --- p.40 / Chapter Chapter 4 --- Discussion --- p.46 / Chapter 4.1 --- The structure of PhAcP in 50% (v/v) [EMIM][BF₄] resembles the native conformation --- p.46 / Chapter 4.2 --- The conformational stability of PhAcP has no observable change in 50% (v/v) [EMIM][BF₄] --- p.47 / Chapter 4.3 --- Insight into the application of enzyme in ionic liquid --- p.48 / Chapter 4.4 --- Limitation of the study --- p.49 / Chapter 4.5 --- Insight into future studies --- p.50 / Chapter Chapter 5 --- Conclusions --- p.51 / Appendix --- p.53 / References --- p.57

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE / Includes bibliographical references. / by Steven Edward Hall. / Ph.D.

Typescript. / Digitized by Kansas Correctional Industries

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Includes bibliographical references. / Ph.D.

Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Chemistry. / Vita. / Includes bibliographical references. / Ph.D.

PART I Controllable Synthesis of Complex Members of the Resveratrol Oligomer Family Chapter 1. Synthesis and Biological Evaluation of Resveratrol Family Oligomeric Natural Products This introductory chapter traces the history of resveratrol, highlighting the substantial interest in elucidating its potential pharmacological benefits and the ensuing impact on the synthetic community. A plethora of research groups have sought to investigate strategies towards accessing higher order oligomers within the resveratrol family, and these approaches provide context for our own endeavors. Chapter 2. Uniquely Functionalized Resveratrol Dimers: Total Syntheses of Hopeanol and Hopeahainol A In this chapter, we expand upon the utility of a divergent strategy, which has enabled the synthesis of multiple oligomeric, resveratrol-based natural products from a common intermediate. We demonstrate applicability to two exceptional dimeric natural products of the resveratrol family, further developing the truly robust nature of this particular synthetic approach. Chapter 3. Harnessing Redox Reactivity: The Total Synthesis of (±)-Vaticanol A In the final installment of this section, we incorporate distinct methodology into the established chemical toolkit for accessing resveratrol oligomers. Targeting a formidable trimeric resveratrol-based natural product, this work takes advantage of several key insights generated from previous endeavors, particularly selective functionalization techniques. PART II Unexploited Paradigms for Chemical Probe Design, Focusing on Cancer Biology Chapter 1. Introduction to the Drug Discovery Landscape The introduction to Part II presents current approaches to the development of small molecule therapeutics and chemical probes, while concurrently obviating their limitations and the necessity to embrace underappreciated paradigms. Such endeavors could be capable of providing access to many elusive molecular targets. Chapter 2. Small Molecule Inhibitors of GPX4: Attempts at Targeted Covalent Inhibition This chapter discusses a recently validated protein target and our efforts to establish a platform for the development of highly selective, irreversible inhibitors. A unique mechanism of enzymatic activity informs a novel approach towards evaluating the capacity to target specific amino acid residues. Chapter 3. In Silico Design of Protein-Protein Interaction Inhibitors Targeted at the RAS Family of GTPases The final chapter embraces in silico inhibitor design as a strategy towards effectively modulating one of the most challenging protein targets of contemporary drug discovery efforts. As a caveat to traditional in silico approaches, this work sought to validate a multivalent ligand approach towards abrogating key protein-protein interactions.

Synthetic chemistry has played a pivotal role in the evolution of modern life. More recently, the emerging field of synthetic biology holds the promise to bring about a paradigm shift with designer microbes to renewably synthesize complex molecules in a fraction of the time and cost. Still, given synthetic chemistry’s superior parsing powers to access a greater number of unnatural end products and nature’s virtuosity at stitching a staggering palette of carbon frameworks with ease, a hybrid approach that leverages the respective strengths of the two fields could prove advantageous for the efficient production of valuable natural molecules and their analogs. In a first demonstration of the hybrid approach where the biosynthesized intermediate is not part of the target molecule’s biosynthetic pathway, we engineered E. coli to produce Z,E-farnesol, which we subsequently transformed into a library of novel analogs of the commercially important amber fragrance Ambrox®, including the first synthetic patchouli scent. In a second demonstration of the hybrid approach, we produced the valuable tocotrienols (vitamin E) from yeast-produced geranylgeraniol in a single step C–C coupling with concomitant regioselective cycloetherification of the most proximal vinyl of the polyene, the first such process of its kind. The novel acid catalyst system that allowed for this unique regioselective cyclization holds promise as an asymmetric proton transfer tool and could open the door to facile asymmetric synthesis of vitamin E and other molecules.

This dissertation focuses on the development of cyclopentadienes as an emerging class of compounds for use in catalysis. Previous work in the Lambert group had established pentacarboxycyclopentadienes (PCCPs) as a promising class of Brønsted acids capable of being used as catalysts in acid-promoted reactions. The ease of their synthesis distinguished them from the comparable BINOL-derived phosphoric acids, and their unique mode of enantioinduction created opportunities for their use in enantioselective reactions. Initial efforts were focused on the synthesis of leading to the development of two complementary methods for their synthesis. Chapter 2 details the improvements made to the transesterification of penta(methoxycarbonyl)cyclopentadiene, which allowed for sterically encumbered alcohols to be used. Further, a new method for accessing the penta-acyl chloride intermediate was developed, leading to the ability for a wide array of electron-deficient PCCPs to be synthesized. The second half of the dissertation examines the use of electrophilic silicon reagents and their use as Lewis acids. Given our ability to access highly electron-deficient cyclopentadienes, the silyl cyclopentadienes were targeted as potential Lewis acids. Chapter 4 details the synthesis of these species, and their characterization. Having established a convenient route to silyl mono(carboxy)tetracyanocyclopentadienides, we examined their use as catalysts in halide abstraction reactions. Benzylic bromides could be activated and subsequently allylated, or arylated with a nucleophilic arene using allyltrimethylsilane as a sacrificial silyl source.

Lau Cheuk Man. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 93-98). / Abstracts in English and Chinese. / Table of Contents --- p.i / Acknowledgements --- p.iii / Abbreviations --- p.iv / Structural Abbreviations for Porphyrin Complexes --- p.v / Abstract --- p.vi / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- General Introduction --- p.1 / Chapter 1.2 --- Activation of Carbon-Hydrogen Bond (CHA) by Transition Metal --- p.2 / Chapter 1.2.1 --- Application of CHA by Transition Metals --- p.3 / Chapter 1.2.2 --- Thermodynamic in CHA by Transition Metals --- p.5 / Chapter 1.2.3 --- Types of Carbon-Hydrogen Activations --- p.6 / Chapter 1.3 --- Carbon-Hydrogen Bond Activation of Aldehydes --- p.14 / Chapter 1.3.1 --- Catalytic Application of CHA of Aldehydes by Transition Metals --- p.14 / Chapter 1.3.2 --- Stability of Intermediate M(COR) --- p.15 / Chapter 1.3.3 --- Issue in Selectivity --- p.16 / Chapter 1.4 --- Structural Features of Rhodium Porphyrins --- p.23 / Chapter 1.5 --- Objective of the work --- p.24 / Chapter Chapter 2 --- Carbon-Hydrogen Activation of Aldehydes by Rh(ttp)Cl and Rh(ttp)Me / Chapter 2.1 --- Introduction --- p.26 / Chapter 2.2 --- CHA of Aldehydes by Rh(ttp)Cl --- p.27 / Chapter 2.2.1 --- Preparation of Rh(ttp)Cl --- p.27 / Chapter 2.2.2 --- Solvents Screening --- p.27 / Chapter 2.2.3 --- Results and Discussion --- p.30 / Chapter 2.3 --- CHA of Aldehydes by Rh(ttp)Me --- p.33 / Chapter 2.3.1 --- Preparation of Rh(ttp)Me --- p.34 / Chapter 2.3.2 --- Results and Discussion --- p.35 / Chapter 2.4 --- Mechanistic Studies --- p.37 / Chapter 2.4.1 --- CHA of Aldehydes by Rh(ttp)Cl --- p.37 / Chapter 2.4.2 --- CHA of Aldehydes by Rh(ttp)R --- p.42 / Chapter 2.5 --- Comparison of the u(C=0) --- p.48 / Chapter 2.6 --- X-ray Data --- p.49 / Chapter 2.7 --- Summary --- p.50 / Chapter Chapter 3 --- CHA of Aldehydes by Rh(ttp)CH2CH2OH and Rh(ttp)+X- / Chapter 3.1 --- Introduction --- p.52 / Chapter 3.2 --- CHA of Aldehydes by Rh(ttp)CH2CH2OH --- p.53 / Chapter 3.2.1 --- Results and Discussion --- p.53 / Chapter 3.2.2 --- Mechanistic Studies --- p.61 / Chapter 3.3 --- CHA of Aldehydes by Rh(ttp)+X- --- p.65 / Chapter 3.4 --- Summary --- p.67 / Conclusion --- p.68 / Experimental --- p.69 / Reference --- p.93 / Appendix I Crystal Data and Processing Parameters --- p.99 / List of Spectra --- p.141 / Spectra --- p.143

Base-promoted CHA of unstrained alkanes with 5,10,15,20-tetratolylporphyrinatorhodium complexes, Rh(ttp)X (X = Cl, H, Rh(ttp)), has been achieved. Rh(ttp)Cl, reacted with n-pentane, n-hexane, n-heptane, c-pentane and c-hexane in the presence of potassium carbonate at 120 °C in 6 to 24 h to give rhodium porphyrin alkyls, Rh(ttp)R, in 29--76% yields. Mechanistic investigations suggested that Rh 2(ttp)2 and Rh(ttp)H are key intermediates for the parallel CHA step. The roles of base are (i) to facilitate the formation of Rh(ttp)Y (Y- = OH-, KCO3 -), (ii) to enhance the CHA rate with alkane and generate Rh(ttp)H by a Rh(ttp)Y species which is more reactive than Rh(ttp)Cl, and (iii) to provide a parallel CHA pathway by Rh2(ttp)2. / c-Octane reacted with Rh(ttp)Cl at 120 °C in 7.5 h in the presence of K2CO3 to yield Rh(ttp)( n-octyl) and Rh(ttp)H in 33% and 58% yields, respectively. Mechanistic investigations indicate that the CCA product is generated from the Rh II(ttp)-catalyzed 1,2-addition of c-octane with Rh(ttp)H. Reaction of c-octane and Rh(ttp)H/Rh2(ttp) 2 (10:1) selectively yielded Rh(ttp)(n-octyl) in 73% at 120 °C in 15 h. The catalyst RhII(ttp) radical cleaves the C-C bond of c-octane to form to a Rh(ttp)-alkyl radical, which then abstracts a hydrogen atom from Rh(ttp)H to generate the Rh(ttp)( n-octyl), and subsequently leading to regeneration of the Rh II(ttp) radical. (Abstract shortened by UMI.) / K2CO3-promoted CHA of the ring-strained cycloheptane with Rh(ttp)Cl at 120 °C in 6 h gave the CHA product Rh(ttp)( c-heptyl) and together with, unexpectedly, the CCA product Rh(ttp)Bn, in 30% and 24% yields, respectively. Mechanistic studies revealed that Rh(ttp)( c-heptyl) undergoes beta-hydride elimination in neutral condition or beta-proton elimination in basic condition followed by reprotonation to give rhodium(III) porphyrin hydride, Rh(ttp)H, and c-heptene. Successive base-promoted CHA of c-heptene with Rh(ttp)H, followed by beta-proton elimination, generates cycloheptatriene. The CHA of cycloheptatriene with Rh(ttp)H formed Rh(ttp)(c-heptatrienyl), which underwent rearrangement with carbon-carbon cleavage at 120 °C in 16 d to yield Rh(ttp)Bn in 96% yield. / The objectives of this research focus on the investigation of carbon-hydrogen bond activation (CHA) and carbon-carbon bond activation (CCA) of alkanes by rhodium porphyrin complexes as well as the mechanistic understanding. / Chan, Yun Wai. / Adviser: Kin Shing Chan. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.