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Dissertations / Theses on the topic 'Chemistry, Biochemistry. Chemistry, Organic'

Author: Grafiati

Published: 4 June 2021

Last updated: 5 February 2022

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1

Easton, Christopher J. "Aspects of biological and organic chemistry, particularly amino acid, cyclodextrin, and free radical chemistry /." Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09S.D/09s.de13.pdf.

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2

Orrling, Kristina M. "On the Versatility of Microwave-Assisted Chemistry : Exemplified by Applications in Medicinal Chemistry, Heterocyclic Chemistry and Biochemistry." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-101356.

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3

Ding, Xiao Dong. "Synthesis and characterization of heme models and spectroelectrochemical studies of heme proteins." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282523.

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To better understand the relationship between the structure and electronic properties of the iron center and the functions of heme proteins, both naturally occurring heme proteins and synthetically prepared heme models have been studied. The reduction potential (E°') and the pH dependence of E°' of nitrophorin 1 (NP1) and myoglobin (Mb) were determined by spectroelectrochemical techniques. The difference in the electrostatic interaction of the Fe(III) center with buried charged groups in the heme pocket of Mb and NP1 is the major factor that causes the 300 mV difference in E°. The pH dependenc

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4

Agha, Kazim Ally. "Synthesis, physicochemical and biochemical properties of C3'-modified 2',5'-linked oligonucleotides." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84457.

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Oligoribonucleotides comprising of 2',5' -linked internucleotide linkages are known to bind selectively to RNA over DNA. The ability to bind to RNA renders them suitable as probes for many biological applications, such as 'antisense technology'. Little is known about the effect of sugar structure (and conformation) on the binding properties of 2',5'-linked oligonucleotides. To get insight into the role of sugar conformation, 2 ',5'-linked oligonucleotides modified at the C3'-position of the furanose ring were synthesized via solid phase synthesis and their binding to complementary singl

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5

Morley, Krista Louise. "Focusing mutagenesis into the active site to improve hydrolase selectivity." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=111830.

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Occasionally, researchers need to modify enzymes through amino acid substitutions to make them more efficient catalysts for organic synthesis. There is still debate over the best protein engineering strategy for improving enzyme enantioselectivity: rational design or directed evolution. Rational design experiments focus mutations close to the active site, while directed evolution experiments often find mutations far from the active site.<br>In this thesis, a combination of the two strategies improved Pseudomonas fluorescens esterase (PFE) for production of a useful synthetic building block for

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6

Roman, Miguel Angel. "Synthesis of branched nucleosides and oligonucleotides containing flexible alkylamine linkers on the heterocyclic bases." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22797.

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The N3 position of thymidine was alkylated with different sized bromoalkyl phthalimide linkers in generally good yields, with no alkylation observed on the sugar ring. The free amino group, available after methylamine deprotection of the phthalimide linker, was protected with the levulinyl protecting group (e.g., 20). Branched 'Y'-shaped nucleic acids containing branching monomer 20 were synthesized using standard solid phase synthetic methodology and complexes of these branched nucleic acids with one and two mole-equivalents of linear complement dA$ sb{10}$ are investigated by thermal melting

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7

Park, Seongsoon. "Enhancing hydrolase activity and selectivity by medium, substrate, and protein engineering." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=83088.

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Researchers use enzymes for enantio- and regioselective reactions because of their high selectivity and activity toward natural substrates. However, researchers sometimes need to modify the reaction system or the enzyme itself to get reliable selectivity and activity when they deal with unnatural substrates. To obtain researcher's need, one can change the solvent, modify the substrates, or alter the enzyme itself. These processes are called medium, substrate, and protein engineering, respectively.<br>This thesis deals with hydrolases, which are classified by EC 3. We applied the proper

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8

Zhou, Wen-Qiang. "The synthesis of amide-linked 2',3'-cyclopropanated dinucleosides and the effect of their incorporation into DNA-strands on duplexation." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40024.

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In order to establish if binding affinity could be improved by conformationally restricting the amide backbone, exo-amide-linked and endo-amide-linked 2$ sp prime$,3$ sp prime$-cyclopropanated dinucleoside analogs (e.g. dimers 35, 54, and 55) have been studied. The dimers were synthesized by coupling the corresponding cyclopropyl acids (5$ sp prime$-end building unit) with aminothymidines (3$ sp prime$-end building unit) by standard peptide synthesis methodology. After proper functionalizations, the dimers were incorporated into DNA sequences, and the effects of their incorporation into DNA-st

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9

Mangos, Maria M. "Factors governing the design, selection and cleavage of sugar-modified duplexes by ribonuclease H." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85579.

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The antisense principle bases its premise in the exquisite complementarity of a synthetic, chemically-modified oligonucleotide to tightly bind with a unique target RNA sequence. Rapid and selective genetic discrimination, as driven by the formation of multiple points of target contact, constitutes a central goal of oligonucleotide therapies. Most synthetic designs have, however, provided little structural insight on the role of the antisense oligonucleotide (AON) in triggering RNA cleavage of preformed hybrids, as catalyzed by a ubiquitous, intracellular enzyme known as ribonuclease H.

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10

Kutterer, Kristina M. K. "Urea and carbamate backbone modified DNA & work towards a synthesis of polyoxin L and analogues." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28808.

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Urea, N-methylurea and carbamate linked thymidine dimers, 38, 37 and 39 respectively, were synthesized efficiently and incorporated into 12- and 19-mer DNA oligonucleotide strands, via solid-phase synthesis. Thermal denaturation studies utilizing complementary single stranded DNA, RNA and duplex DNA, indicated selectivity of binding of all three backbone modified oligomers to single stranded DNA. The oligomer containing dimer 37 exhibited the strongest binding to single stranded DNA. Carbamate and 5$ sp prime$-N-methylurea modified dimers suitable for the preparation of longer nucleoside homop

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11

Chefson, Amandine. "Towards the use of P450 enzymes in synthesis : cofactor replacement and activity of CYP3A4 in non-aqueous media." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100784.

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Enantioselective synthesis is one of the most important challenges of today's synthetic chemists. In particular, the hydroxylation of non-activated C-H bonds remains a significant challenge that few chemical catalysts have succeeded to overcome. The P450 enzymes, a family of heme-containing monooxygenases including more than 5000 known isoforms, are gaining considerable attention due to their ability to catalyze the very difficult regio- and stereo-selective oxidation of inactivated C-H bonds. The use of such enzyme is however limited by their functional complexity, low activity, need for cofa

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12

Krupa, Joanne C. (Joanne Christine). "Coenzyme analogs in dehydrogenase-catalyzed reactions." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39934.

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To enhance the performance of dehydrogenases in synthetic organic chemistry, coenzyme analogs of NAD(P)$ sp+$/NAD(P)H were examined. Our study shows that dehydrogenases are more efficient with NAD(P)$ sp+$ than with the APAD(P)$ sp+,$ FPAD$ sp+$ or SPAD(P)$ sp+$ under non-regenerating oxidative conditions in terms of yields. Under regenerating conditions, APAD$ sp+$ often exceeded NAD$ sp+$ in terms of product formation. Lower yields were observed with SPAD(P)$ sp+$ and FPAD$ sp+.$ These coenzyme analogs also displayed reduced reactivity, but APAD$ sp+$ was the most promising of the three. In

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13

Qiu, Wei. "Design and synthesis of conformationally and topographically constrained amino acids as peptidomimetics." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/280486.

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A major goal of peptide research has been to elucidate or understand the relationships between a peptide's three-dimensional structure and its biological activity. De Novo design of peptide mimetics requires assembling all components necessary for molecular recognition and transduction, which needs the proper choice of a template that can place the key side chain residues in 3D space. Two widely used methods are novel β-substituted amino acids and conformationally constrained secondary structure mimetics. In this thesis, we report our efforts to fulfill the aforementioned criteria in synthesiz

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14

Labell, Rachel. "Synthesis and characterization of galactosyl lipids that bind HIV-1 gp120." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/289764.

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The HIV-1 virus has a protein, gp120, on its surface that is responsible for the initial recognition between the virus and human cells by binding to the CD4 receptor, which is found on many types of human cells. An alternative receptor, galactosylceramide (GalCer), has also been identified. It binds to HIV-1 gp120 and facilitates the infection of human cells via a CD4 independent mechanism. The goal of this research project was to design, synthesize, and test the effectiveness of galactosyl lipids that bind to gp120. A versatile synthesis was developed and used to synthesize five different Gal

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15

Bowen, Martina E. "I. Use of 9-methylfluorene as an indicator for organometallic titrations II. Synthesis of a branched polyethylene glycol linker for peptide ligands III. Synthesis of a linker for peptide ligands and a study of its pH sensitivity." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/290107.

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This work details the synthesis of some useful organic molecules: (I) 9-Methylfluorene was tested as an indicator in the titration of commonly used organometallic reagents. This indicator is readily prepared in three steps from fluorenone. In THF solution the deprotonated indicator is red and exhibits a sharp endpoint. The highly basic reagents sec-butyllithium and tert -butyllithium can be titrated in ether solution, where the color of the deprotonated indicator is yellow. (II) A branched, polyethylene glycol based linker for peptide ligands was designed and synthesized. The linker needed to

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16

Wallace, Clare E. "Investigating Conformational Changes in Sialylations by using a C-3 Labeled Sialyl Donor." Thesis, Southern Illinois University at Edwardsville, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1560926.

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<p> The synthesis of complex carbohydrates containing sialic acid is very challenging by chemical methods, in part due to the competing elimination reaction, as well as poor stereocontrol. One major disadvantage in the field is the limited knowledge of the mechanism of sialylations. The mechanism is believed to go through an oxacarbenium ion intermediate. Recent findings suggest the existence of an all-axial conformation of the oxacarbenium ion that might be important in controlling the overall efficiency of sialylations. As a part of a general research goal to gain a better understanding

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17

Simpson, Levi Samuel. "The development and application of methodologies for the study of sulfate monoesters in biological systems." [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3297086.

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Thesis (Ph. D.)--Indiana University, Dept. of Chemistry, 2007.<br>Title from dissertation home page (viewed Sept. 26, 2008). Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1019. Adviser: Theodore S. Widlanski.

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18

Amato, Nicholas J. "Impact of DNA Structure and Aeropyrum pernix Single-Strand DNA Binding Protein on Oxidative Damage to DNA." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1372296254.

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19

Mukherjee, Herschel. "On the Biological Activity of the Natural Product (+)-Avrainvillamide." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17467289.

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Nucleophosmin (NPM1) is a multifunctional phosphoprotein localized predominantly within the nucleoli of eukaryotic cells. Mutations within its C-terminal domain are frequently observed in patients with acute myeloid leukemia (AML), are thought to play a key role in the initiation and progression of the disease, and result in aberrant, cytoplasmic localization of the mutant protein. It has previously been demonstrated that the electrophilic antiproliferative natural product (+)-avrainvillamide binds to proteins, including nucleophosmin, by ¬S-alkylation of cysteine residues. In this thesis we r

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20

Tahira, Ambreen. "Synthesis of Bivalent Organothiophosphate Inhibitors and Their Inhibition of Butyrylcholinesterase| Studies towards a Potential Treatment of Cognitive Loss Associated with Alzheimer's Disease." Thesis, California State University, Long Beach, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10636600.

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<p> Recently, it has been shown that a decrease in activity of acetylcholinesterase (AChE) in AD patients is compensated by an increase in butyrylcholinesterase (BuChE) activity. Therefore, BuChE also becomes a significant target in the treatment of cognitive loss associated with Alzheimer’s disease. While the majority of drug development so far has centered on AChE inhibitors in order to increase the acetylcholine level in AD patients, the development of specific and potent BuChE inhibitors have also begun to attract attention. We recently synthesized and assayed a library of bisthiopho

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21

Priem, Jessica. "Main Group Elements Supported by pi-Conjugated, Nitrogen-Rich Ligand Frameworks and the Catalytic Formation of Guanidines." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28656.

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This thesis investigated the structure and reactivity of group 13 elements boron, aluminum and gallium supported by nitrogen rich ligand systems. The majority of this work deals with N,N',N"-trisubstituted guanidinate ligands and N,N'-disubstituted-1,8-diaminonaphthalene dianionic ligand frameworks. New methods for the catalytic formation of guanidines have also been explored. Chapter 1 outlines the basics of using nitrogen rich compounds as ligands. This includes the introduction of guanidinates as supporting ligands and the description of using a rigid backbone system such as an N,N'-disubst

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22

Kaye, P. T. """Of molecules and men"" : inaugural lecture delivered at Rhodes University." Rhodes University, Grahamstown, 1989. http://hdl.handle.net/10962/d1020712.

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23

Sua, Andy. "Using Metal-Organic Framework Film as a Drug-Eluting Stent Coating." Thesis, California State University, Long Beach, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=10975741.

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<p> Metal-organic frameworks have a wide range of applications including gas separation, gas capture, catalysis and drug delivery. Due to the in-stent thrombosis of the current drug-eluting stents we propose replacing the toxic polymer with a more biodegradable MOF thin film consisting of MIL-88b. The MIL-88b thin film was formed on functionalized gold through a direct crystallization method and was confirmed using x-ray diffraction (XRD) and Fourier- transform infrared spectroscopy (FTIR). Possible ibuprofen encapsulation and elution was confirmed through FTIR and UV-VIS spectroscopy. The MIL

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24

Cavagnero, Silvia 1962. "Structure-activity studies of delta-selective opioid analogues." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/278183.

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The two structurally different peptides DPDPE and Dermenkephalin show a similar remarkably high affinity and selectivity for the delta opioid receptor subtype. An effort has been made to gain some insight into the factors responsible for the recognition ability of these two molecules by synthesizing some DPDPE-Dermenkephalin peptide hybrids and some conformationally restricted Dermenkephalin analogues. The results of the binding and the in-vitro bioassays have been compared with those of the parent peptides. A general decrease in receptor affinity has been observed in the peptide hybrids while

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25

Ferguson, Ronald Dale 1966. "Design, synthesis and biological screening of combinatorial chemical libraries." Thesis, The University of Arizona, 1996. http://hdl.handle.net/10150/278584.

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Although combinatorial libraries owe their inception to applications in peptide and bacteriophage libraries, the breadth of current applications include solution phase chemical reaction optimization, material science investigation, natural products modifications, and agricultural research. As a conceptual application, combinatorial library techniques can enhance a researcher's ability to transcend beyond the examination of one or several compounds to that of thousands or millions of these species simultaneously. The work described here, limited to scaffolded combinatorial chemical libraries, f

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26

Joshi, Hemant K. "Synthetic, structural, spectroscopic and computational studies of metal-dithiolates as models for pyranopterindithiolate molybdenum and tungsten enzymes: Dithiolate folding effect." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280480.

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Coordination by an axial oxo and an equatorial ene-dithiolate group is a salient feature of the active sites of the mononuclear pyranopterin Mo/W enzymes. Discrete mononuclear model complexes encompassing these features are important in understanding the metal-ligand interactions in these active sites. The compounds (Tp*)ME(S-S) (M = Mo, W; E = O, NO) and Cp₂M(S-S) (M = Ti, Mo, W) (where Tp* is hydrotris(3,5-dimethyl-1-pyrazolyl)borate, Cp is η⁵-cyclopentadienyl, S-S represents a generic ene-1,2-dithiolate ligand for example 1,2-benzenedithiolate and 3,6-dichloro-1,2-benzenedithiolate) provide

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27

Clapp, Paula Jean 1968. "Visible-light induced reactions in lamellar phospholipid assemblies." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282185.

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Cyanine photosensitizers are visible-light absorbing dyes commercially useful in photography and available in a variety of structures with tunable redox, absorptivity and excited state properties. The areas of research described in this dissertation all utilize cyanine dyes to photosensitize various processes to visible-light within the confines of lamellar phospholipid assemblies. In Chapter III, an efficient three component, liposome-bound photochemical molecular device for transfer of energy and electrons is described. A porphyrin (free base or metallated) serves as the energy donor, a cyan

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28

Bondurant, Bruce. "Photoinduced release of contents from sterically stabilized liposomes." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284207.

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The design of sterically stabilized liposomes with surface grafted poly(ethylene glycol) (PEG-liposomes) for drug delivery requires a very low rate of leakage so that drugs will remain encapsulated during the 24 to 48 hr that these liposomes remain in circulation. This design can interfere with the rapid release of the encapsulated drugs at the site of action. An effective technique for the photodestabilization of PEG-liposomes is described. Photosensitive PEG-liposomes containing the polymerizable lipid 1,2-bis[10-(2',4 '-hexadienoyloxy)decanoyl]-sn-glycero-3-phosphatidylcholine (bis-SorbPC₁₇

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29

Oliver, John William Kidder. "Design and Improvement of the Biosynthesis of 2,3--Butanediol from CO2 by Metabolic Engineering of Cyanobacterium Synechococcus elongatus PCC7942." Thesis, University of California, Davis, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3685273.

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<p> This dissertation describes metabolic engineering of cyanobacterium <i> Synechococcus elongatus</i> PCC7942 as a photosynthetic host for the conversion of CO<sub>2</sub> into 2,3-butanediol. Current advances in pathway design, genetic tool development, and yield improvement are described (Chapter 1). A pathway for the synthesis of 2,3-butanediol is designed based on collective concepts of pathway strength, robustness, and irreversibility, and extensively tested through the generation of mutants (Chapter 2). This pathway is then optimized through modulation of translation by combinatorial m

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30

Onaran, Mehmet B. "Design and synthesis of bioactive small molecules and high-throughput identification of enantiomeric excess." View abstract/electronic edition; access limited to Brown University users, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3319114.

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31

Stein, Natalia. "Spectroscopic and electrochemical studies of Shewanella oneidensis cytochrome c nitrite reductase, and improving c-heme expression systems." Thesis, The University of Wisconsin - Milwaukee, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3685085.

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<p> In this work the redox properties of cytochrome c nitrite reductase (CcNiR), a decaheme homodimer that was isolated from <i>S. oneidensis,</i> were determined in the presence and absence of the strong-field ligands cyanide and nitrite. Four hemes per CcNiR protomer are hexa-coordinate with tightly bound axial histidines, while the fifth (active site) has one tightly bound lysine and a distal site that can be open, or contain exogenous ligands such as the substrate nitrite. Controlled potential electrolysis in combination with UV/visible absorption (UV-vis) and electron paramagnetic resonan

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32

Lamparski, Henry Gennady. "Polymerization in two-dimensional assemblies of sorbyl-containing lipids." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186492.

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Mono- and bis-substituted phosphatidylcholines (PC) containing a polymerizable sorbyl ester group at the acyl chain terminus were synthesized. The thermotropic phase behavior, two-dimensional polymerizability, and polymerized assemblies stability were investigated. The thermotropic phase behavior of mono- and bis-sorbylPCs was examined by differential scanning calorimetry. Each SorbPC exhibited a single endotherm which occurred at temperatures below the main phase transition (T(m)) of the corresponding linear saturated PC. Variations in the chain length of bis-SorbPC resulted in a pronounced o

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33

Colla, Alexander J. "Development of an efficient approach for the incorporation of a series of fluorotyrosines in peptides." Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1603748.

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<p> Site-directed mutagenesis provides a powerful tool in the study of enzyme function. Residues suggested to be important for catalysis can be readily mutated and the energetic effects measured. However, the limited repertoire of naturally occurring amino acids constrains the substitutions that can be made. To obtain a deeper understanding of how enzymes work requires using unnatural amino acids to systematically perturb enzymatic residues. For example, hydrogen bonds in an ‘oxyanion hole’ are a common feature of enzyme active sites and often suggested to be important for catalysi

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Menegatti, Stefano. "Design, Selection, and Development of Novel Peptide Ligands for Bioseparations and Diagnostics." Thesis, North Carolina State University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3575894.

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<p> The relevance of protein-based biopharmaceuticals has increased dramatically in the past decades and a variety of products are now available for human therapy. Antibodies in particular are currently the most heavily consumed protein therapeutics, with a current market volume expected to reach 1 trillion US$ in 2015 and a compound annual growth rate (CAGR) of 3-6%. Meeting the increasing demand for these therapeutics at lower prices while complying with increasingly stringent regulatory environments, calls for the development of new technologies and platform approaches for efficient downstr

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Kriss, Caroline Theresa. "Conformational analysis of O-linked glycopeptides related to enkephalin and nuclear pore proteins." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/284116.

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The effect of O-linked glycosylation on peptide conformation has been studied in pursuit of understanding one of the natural roles of carbohydrates, and with an interest in drug design. Solution conformations were analyzed using a combination of NMR, molecular modeling, and kinetics techniques. Variations in peptide sequence, carbohydrate, and stereochemistry of linkage were made. Glycosylation of enkephalin analogs at the Ser⁶ position of the sequence Tyr-c-[D-cys-Gly-Phe-D-cys]-Ser-Gly-CONH₂ with a glucose moiety affected only the exocyclic portion of the molecule. An α-linkage constrained t

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Brotherton, Carolyn Adams. "Investigations of the Biosynthesis and Structure of Colibactin, a Cytotoxin Made by Human-Associated Escherichia Coli." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:26718729.

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Humans exist in symbiosis with trillions of bacteria that are collectively referred to as the human microbiota. While commensal microbes are essential for health, some resident microbes can promote disease. Certain strains of human-associated Escherichia coli cause double-strand breaks in host DNA through the production of colibactin, a genotoxin of unknown structure. To broaden our understanding of the chemistry of the human microbiota, we sought to elucidate the structure of colibactin and characterize its biosynthetic pathway. We first characterized the self-resistance mechanism in colibact

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Hamberg, Anders. "Serine Hydrolase Selectivity : Kinetics and applications in organic and analytical chemistry." Doctoral thesis, KTH, Biokemi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12831.

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The substrate selectivities for different serine hydrolases were utilized in various applications, presented in papers I-VI. The articles are discussed in the thesis in view of the kinetics of the enzyme catalysis involved. In paper I the enantioselectivities towards a range of secondary alcohols were reversed for Candida antarctica lipase B by site directed mutagenesis. The thermodynamic components of the enantioselectivity were determined for the mutated variant of the lipase. In papers II-III Candida antarctica lipase B was engineered for selective monoacylation using two different approach

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Shokeer, Abeer. "Design of Glutathione Transferase Variants for Novel Activities with Alternative Substrates." Doctoral thesis, Uppsala universitet, Institutionen för biokemi och organisk kemi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-119768.

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Glutathione transferases (GSTs) play a pivotal role in cellular defense, since they are main contributors to the inactivation of genotoxic compounds of exogenous and endogenous origins. Directed evolution was used to improve the catalytic activities of Theta class GST T1-1 toward different substrates. The library was constructed by recombination of cDNA coding for human GST T1-1 and rodent Theta class GSTs, resulting in the F2-F5 generations. The clones were heterologously expressed in Escherichia coli and screened for variants with enhanced alkyltransferase activity. A mutant, F2:1215, with a

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39

Houghton, Stephen Richard. "Improving access to biologically and pharmaceutically relevant molecules by understanding mechanisms of biosynthesis and improving chemical synthesis." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2008. http://wwwlib.umi.com/cr/syr/main.

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Marwitz, Adam John Von 1981. "The chemistry of 1,2-dihydro-1,2-azaborine and nitrated lipids." Thesis, University of Oregon, 2010. http://hdl.handle.net/1794/11299.

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xxv, 468 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.<br>1,2-Dihydro-1,2-azaborine is a six-membered aromatic heterocycle that is related to the quintessential aromatic molecule, benzene, via the replacement of a CC fragment in benzene with an isoelectronic BN bond-pair. Like the benzene motif, 1,2-dihydro-1,2-azaborine derivatives could provide opportunities in fields ranging from medicine to materials. Recent breakthroughs in the synthesis of 1,2-dihydro-1,2-azaborine have led to a burge

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Xiong, Chiyi. "Asymmetric synthesis of conformationally and topographically constrained amino acids as peptidomimetics: An approach to design and synthesis of opioid receptor selective ligands." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280393.

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As part of continuing efforts to obtain backbone and side chain conformationally constrained, novel amino acids,¹⁻⁷ we have successfully developed the asymmetric synthesis of β-phenyl-substituted cysteine, tryptophan, and serene derivatives. In this approach, the key intermediate, enantiomerically pure 3-phenylaziridine-2-carboxylic ester, was prepared from an α, β-unsaturated ester by employing the Sharpless asymmetric dihydroxylation. The aziridine was treated with 4-methoxybenzylthiol, indole, and acetic acid to give β-phenyl-substituted cysteine, tryptophan, and serine, respectively, in a

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Bonner, Grady Gregg 1965. "Synthesis, pharmacology, and structural analysis of opioid peptides: Cyclic somatostatin analogs which include unusual amino acids with conformationally restricted side-chain groups." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282318.

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This work relates the activities of Somatostatin-derived opioid peptides to their 3-dimensional structures. Due to the flexability of peptides, they adopt multiple conformations. This flexibility leads to ambiguity in the development of structure-activity profiles. Here flexibility is reduced by incorporation of amino acids with conformationally restricted side-chain groups. These groups are restricted to certain topographies by cyclization or biased through substitution at the beta carbon. The opioid activities of these peptides are determined by brain binding radioligand competition assay, i

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Liang, Tao. "Chiral Phosphoric Acids and Alkaline Earth Metal Phosphates Chemistry." Thesis, University of South Florida, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3632228.

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<p> Asymmetric synthesis and catalysis is one of the leading research areas in chemistry society, for its versatility and efficiency in obtaining chiral molecules that found the vast majority in natural active compounds and synthetic drugs. Developing asymmetric catalytic methodology is at the frontier in both industrial and academic research laboratories. Enantioselective organocatalysis has emerged as a powerful synthetic tool that is complementary to metal-catalyzed transformations. The development of chiral phosphoric acid and metal phosphate as catalysts has been a breakthrough in recent

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Armitage, Bruce Alan. "Photoinduced electron transfer, energy transfer and polymerization reactions in phospholipid membranes." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186212.

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The differential physical properties found at different depths of a phospholipid membrane permit design of systems for vectorial reactions (which are not possible in isotropic solution). In the system described in Chapter IV, a hydrophobic electron donor (triphenylbenzylborate) binds to the membrane interior while a hydrophilic electron acceptor (a cyanine dye) binds to the surface. Irradiation with red light leads to vectorial electron flow via photoinduced electron transfer (PET), as monitored by fluorescence quenching and photobleaching techniques. The PET reaction efficiency is enhanced ov

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Lin, Ying. "Design and synthesis of conformationally constrained glucagon analogues to study the conformational features important for glucagon bioactivity." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186227.

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We have synthesized ten glucagon analogues that are either conformationally constrained systematically in the middle portion of the molecule, or modified from the known superagonist analogue [Lys¹⁷,¹⁸, Glu²¹]glucagon to study the structure-activity relationships of glucagon. The analogues were prepared using the solid-phase peptide synthesis method. Cyclizations were accomplished by forming the side chain lactam (amide) bridges on the resin. All peptide analogues were cleaved from the solid support, deprotected by the low-high HF procedure, and purified by a combination of gel filtration chrom

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Malasi, Wilhelm S. "Synthesis and complexation of functionalized mixes thia-aza-macrocyclic and medium sized ligands." Akron, OH : University of Akron, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1239210466.

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Thesis (Ph. D.)--University of Akron, Dept. of Chemistry, 2009.<br>"May, 2009." Title from electronic dissertation title page (viewed 11/25/2009). Advisor, Michael J. Taschner; Committee members, David Modarelli, Jun Hu, Wiley J. Youngs, Amy Milsted; Department Chair, Kim C. Calvo; Dean of the College, Chand Midha; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

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Azizeh, Bassem Yousef. "Structure-activity relationship analysis: Developing glucagon agonists and antagonists for studies of glucagon action in normal and diabetic states." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282252.

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Several glucagon analogues containing substitutions in the N-terminal region, in particular residues 1, 5, 6, 9 and 10 (histidine, threonine, phenylalanine, aspartic acid and tyrosine, respectively), were synthesized. In addition four β-methylphenylalanine isomers were introduced at position ten to assess the role of these topographical modifications on hormone activity, and to study the effect of constraint and biased conformational preferences of the side chain moieties on biological activity. All the analogues were synthesized by solid-phase methodology, purified to homogeneity by reverse-p

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Patel, Dharmesh J. "Biomimetic Studies of Oxidation Reactions by Metalloporphyrins through Ligand Effect and Kinetic Studies of Photo-Generated Porphyrin-Iron(Iv)- Oxocompound II Models." TopSCHOLAR®, 2018. https://digitalcommons.wku.edu/theses/2091.

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High-valent iron(IV)-oxo porphyrins are the central oxidizing species in hemecontaining enzymes and synthetic oxidation catalysts. Many transition metal complexes have been extensively studied as models of the ubiquitous cytochrome P450 enzymes to probe the sophisticated oxygen atom transfer (OAT) mechanism as well as to invent enzyme-like oxidation catalysts. In this work, two metalloporphyrin complexes have been successfully synthesized, and spectroscopically characterized. A new photochemical entry to porphyrin-iron(IV)-oxo derivatives, commonly referred to as compound II models, was also i

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Idippily, Nethrie. "EVALUATION OF A SMALL MOLECULE AGONIST OF EPHA2 RECEPTOR TYROSINE KINASE AND COPALIC ACID ANALOGS AS PROSTATE CANCER THERAPEUTICS." Cleveland State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=csu1525722508418914.

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Chen, Chou-Hsiung. "Total synthesis of argyrin A and analogues thereof." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/13296/.

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The cyclin dependent kinase inhibitor p27 is one of the most frequently dysregulated tumour suppressor protein in human cancers. A reduction in the level of cellular p27 is frequently due to increased proteasome-dependent degradation. Recently, studies show that the macrocyclic octapeptide argyrin A induced an increase in cellular p27 levels by preventing the turnover of the protein via inhibition of proteasome function. In order to investigate this interesting biological property, this project embarked on the total synthesis of argyrin A, a naturally occurring macrocyclic peptide originally i

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