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Synthesis and evaluation of inhibitors targeting Coenzyme : a biosynthesis and metabolism in Staphylococcus aureus
Thesis (PhD)--University of Stellenbosch, 2010.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : University of Stellenbosch
2010
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| _version_ | 1867614067900809216 |
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| access_status_str | Open Access |
| author | Van der Westhuyzen, Renier |
| author2 | Strauss, Erick |
| author_browse | Strauss, Erick Van der Westhuyzen, Renier |
| author_facet | Strauss, Erick Van der Westhuyzen, Renier |
| author_sort | Van der Westhuyzen, Renier |
| collection | Thesis |
| dc_rights_str_mv | University of Stellenbosch |
| description | Thesis (PhD)--University of Stellenbosch, 2010. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/5464 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:46:09.042Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2010 |
| publishDateRange | 2010 |
| publishDateSort | 2010 |
| publisher | Stellenbosch : University of Stellenbosch |
| publisherStr | Stellenbosch : University of Stellenbosch |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/5464 Synthesis and evaluation of inhibitors targeting Coenzyme : a biosynthesis and metabolism in Staphylococcus aureus Van der Westhuyzen, Renier Strauss, Erick University of Stellenbosch. Faculty of Science. Department of Chemistry and Polymer Science Inhibitor Antibiotics Synthesis Enzyme Biochemistry Thesis (PhD)--University of Stellenbosch, 2010. ENGLISH ABSTRACT: The human pathogen Staphylococcus aureus is a major cause of hospital-, and more recently, community-acquired infections. The rate at which this organism is acquiring resistance to antibiotics is increasing while the development of new antibiotics is slowing down. There is therefore a desperate need for new antistaphylococcal agents, and in particular ones with novel mechanisms of action that can be used to circumvent established resistance pathways. Unlike humans, S. aureus employs the essential cofactor coenzyme A (CoA) as its major low molecular weight thiol. Together, CoA and the enzyme CoA disulfide reductase (CoADR) are responsible for maintaining the internal redox homeostasis in this organism, and disruption of this balance (or reduction of CoA levels) may therefore be potential mechanisms by which new antistaphylococcal agents may act. In this study we set out to achieve this by direct inhibition of CoADR, and by inhibition of one or more of the CoA biosynthetic enzymes. For the inhibition of CoADR CoA analogues containing Michael acceptors were designed and prepared by employing a chemo-enzymatic approach. This strategy involved the chemical synthesis of pantothenamides containing α,β-unsaturated ester, ketone and sulfone moieties as Michael acceptors, followed by their biotransformation into the corresponding CoA analogues by three CoA biosynthetic enzymes. The compounds prepared in this manner all inhibited CoADR potently. A full kinetic evaluation of the inhibition by these compounds suggested that these compounds act by alkylation of the single active site cysteine of CoADR in an irreversible fashion. In this study we also set out to determine the mechanism of action of the antistaphylococcal compound CJ-15,801, which is structurally similar to pantothenic acid, the biosynthetic precursor of CoA. Due to this similarity we proposed that the antibiotic properties of CJ-15,801 are based on the inhibition of enzymes involved in CoA biosynthesis and metabolism. Our investigations confirmed that the second enzyme of the CoA pathway, phosphopantothenoylcysteine synthetase (PPCS), acts as the main target of CJ-15,801. These studies were followed by an investigation into alternative synthetic methodologies for the preparation of CJ-15,801 and its analogues. As a result an established Pd-catalyzed coupling reaction was modified and applied in the third known total synthesis of CJ-15,801, as well as of several of its analogues. This protocol has several advantages over its predecessors, most importantly its suitability for preparing these compounds on large (up to one gram) scale. AFRIKAANSE OPSOMMING: Die menslike patogeen Staphylococcus aureus is 'n wesenlike oorsaak van hospitaal- en meer onlangs gemeenskap-verworwe infeksies. Terwyl die tempo waarteen hierdie organisme weerstandbiedig teenoor antibiotika raak toeneem, neem die ontwikkeling van nuwe antibiotiese middels af. Dit is dus van kardinale belang dat nuwe antistafilokokale middels ontwikkel word, en meer spesifiek antibiotika met 'n nuwe meganisme van aksie wat gebruik kan word om huidige weerstandbiedende padweë te ontwyk. In teenstelling met mense, gebruik S. aureus die essensiele kofaktor koënsiem A (KoA) as sy vernaamste lae molekulere gewig tiol. Die ensiem KoA disulfied reduktase (KoADR) en KoA is saam verantwoordelik om die interne redoks homeostase in hierdie organisme te handhaaf, en ontwrigting van die balans (of vermindering van KoA vlakke) kan dus potensieel 'n meganisme van aksie wees waardeur nuwe antistafilokokale middels kan optree. In hierdie studie het ons gepoog om dit te bewerkstellig deur KoADR direk te inhibeer, asook deur inhibisie van een of meer van die KoA biosintetiese ensieme. Vir die inhibisie van KoADR is KoA-analoë wat Michael-akseptor groepe bevat ontwerp en berei deur van 'n chemo-ensiematiese benadering gebruik te maak. Met hierdie strategie is pantoteenamiede gesintetiseer wat α,β-onversadigde ester, ketoon en vinielsulfoon funksionaliteite as Michael-akseptore bevat, gevolg deur biotransformasie na die ooreenstemmende KoA-analoë met behulp van drie CoA biosintetiese ensieme. Die verbindings gesintetiseer met hierdie metode het almal KoADR potent geinhibeer. 'n Omvattende kinetiese evaluasie het voorgestel dat al hierdie verbindings funksioneer deur alkielering van die enkele aktiewe setel sisteïen van KoADR op 'n onomkeerbare wyse. In die studie het ons ook gepoog om die meganisme van aksie van die antistafilokokale verbinding CJ-15,801 te bepaal. Hierdie verbinding is struktureel soortgelyk aan pantoteensuur, die biosintetiese voorganer van KoA. As gevolg van hierdie ooreenkomste het ons voorgestel dat die antibiotiese aktiwiteit van CJ-15,801 die gevolg is van die inhibisie van een of meer van die ensieme wat verantwoordelik is vir KoA biosintese en metabolisme. Ons ondersoeke het bevestig dat die tweede ensiem in die KoA biosintetiese padweg, naamlik fosfopantotenoïelsisteïensintetase, die hoofteiken van CJ-15,801 is. Hierdie studies is gevolg deur die ondersoek van alternatiewe metodologieë vir die sintese van CJ-15,801 en analoë daarvan. 'n Gevestigde Pd-gekataliseerde koppelings reaksie was gevolglik gemodifiseer en toegepas om slegs die derde totale sintese van CJ-15,801 te bewerkstelling, asook die sintese van verskeie analoë daarvan. Hierdie protokol hou verskeie voordele in vergelyking met sy voorgangers, waarvan die mees belangrikste die bereiding van hierdie verbindings op groot (tot een gram) skaal is. Doctoral 2010-11-22T05:52:42Z 2010-12-15T10:50:25Z 2021-02-01T03:00:15Z 2010-12 Thesis http://hdl.handle.net/10019.1/5464 en_ZA University of Stellenbosch application/pdf Stellenbosch : University of Stellenbosch |
| spellingShingle | Inhibitor Antibiotics Synthesis Enzyme Biochemistry Van der Westhuyzen, Renier Synthesis and evaluation of inhibitors targeting Coenzyme : a biosynthesis and metabolism in Staphylococcus aureus |
| title | Synthesis and evaluation of inhibitors targeting Coenzyme : a biosynthesis and metabolism in Staphylococcus aureus |
| title_full | Synthesis and evaluation of inhibitors targeting Coenzyme : a biosynthesis and metabolism in Staphylococcus aureus |
| title_fullStr | Synthesis and evaluation of inhibitors targeting Coenzyme : a biosynthesis and metabolism in Staphylococcus aureus |
| title_full_unstemmed | Synthesis and evaluation of inhibitors targeting Coenzyme : a biosynthesis and metabolism in Staphylococcus aureus |
| title_short | Synthesis and evaluation of inhibitors targeting Coenzyme : a biosynthesis and metabolism in Staphylococcus aureus |
| title_sort | synthesis and evaluation of inhibitors targeting coenzyme a biosynthesis and metabolism in staphylococcus aureus |
| topic | Inhibitor Antibiotics Synthesis Enzyme Biochemistry |
| url | http://hdl.handle.net/10019.1/5464 |
| work_keys_str_mv | AT vanderwesthuyzenrenier synthesisandevaluationofinhibitorstargetingcoenzymeabiosynthesisandmetabolisminstaphylococcusaureus |