Dissertations / Theses on the topic 'Shifting boundaries'
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Archer, Carol, University of Western Sydney, of Performance Fine Arts and Design Faculty, and School of Design. "Skin to work : shifting materialities, ambiguous boundaries." THESIS_FPFAD_SD_Archer_C.xml, 1998. http://handle.uws.edu.au:8081/1959.7/380.
Full textMaster of Arts (Hons) (Visual Arts)
Archer, Carol. "Skin to work : shifting materialities, ambiguous boundaries /." View thesis, 1998. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030905.111802/index.html.
Full text"Submitted in part fulfillment for the degree of M(Hons) in Visual Arts, University of Western Sydney, Nepean" Bibliography : p. 40-42.
Cassidy, Margaret Jillian. "Shifting boundaries : the art of Eileen Mayo." Thesis, University of Canterbury. Art History, 2000. http://hdl.handle.net/10092/9694.
Full textAkyurek, Engin Ahmet. "Changing Conceptions Of European Identity And Shifting Boundaries." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12604993/index.pdf.
Full textHenwood, Melanie. "Shifting sands : contested boundaries in adult social care." Thesis, University of Kent, 2015. https://kar.kent.ac.uk/54339/.
Full textGoldmann, Gustave J. (Gustave Joseph) Carleton University Dissertation Sociology and Anthropology. "The shifting of ethnic boundaries: causes, factors and effects." Ottawa, 1994.
Find full textChen, Shining Sheue Yun. "State-press relations in Taiwan : the shifting boundaries of control." Thesis, University of Stirling, 1994. http://hdl.handle.net/1893/2187.
Full textKennedy, Fenella Kate. "Movement Writes: Four Case Studies in Dance, Discourse and Shifting Boundaries." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1563804914734557.
Full textChavez, Miguel Angel. "The Shifting Borders of Egypt." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc799465/.
Full textRoberts, Amanda. "“Shifting Boundaries and Unfixing Fixities”: Boundary Crossing in Pauline Melville’s The Ventriloquist’s Tale." Thesis, Stockholm University, Department of English, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-8677.
Full textA central theme in Pauline Melville’s novel, The Ventriloquist’s Tale, is the question of endogamy and exogamy, with the opposing alternatives embodied in Melville’s characters. This theme has received much attention in the critical commentaries generated by the novel, with a prevailing number of critics claiming that Melville proposes endogamy as the only option for indigenous communities to remain intact. However, such an argument overlooks the significant fact that Melville’s characters are always already the offspring of exogamous encounters, through which a multiplicity of boundaries have been permeated. Furthermore, the spatial motifs developed in the novel can be seen to undermine commonly accepted delimitations of supposedly homogenous groups, the nation-state constituting the prime example, and this in turn profoundly alters the notion of mixing. Consequently, contending that Melville even enters a debate on endogamy and exogamy stems from a predisposition to see the world in other terms than those Melville sets out in her novel. The nature of boundaries and borders in Melville’s fictitious world are therefore explored using Benedict Anderson’s Imagined Communities as a framework. This examination shows that the novel undermines the notion of the nation-state as a homogenous entity and reveals a global structure that dictates and drives interaction on a global scale. Consequently, instead of a debate on exogamy, we see in the novel an exploration and dismantling of notions of borders, boundaries and barriers between individuals and groups of people.
Kruger, Heidi Ann. "Shifting Interorganizational Boundaries: An Empirical Examination of the Implications of Strategic Alliance Exit." Doctoral thesis, Universitat Ramon Llull, 2019. http://hdl.handle.net/10803/667508.
Full textLa terminación de las alianzas estratégicas ha atraído la atención de los académicos durante décadas. Desde los inicios de la investigación en materia de alianzas, los estudios han reconocido el carácter flexible y temporal de los acuerdos entre empresas. La terminación de una alianza constituye una fase importante del ciclo de vida de la misma y una actividad básica de la reestructuración del portfolio de alianzas. Investigaciones previas se han centrado en descubrir los motivos de la terminación, pero son pocos los estudios que han analizado sus consecuencias. Esto resulta sorprendente teniendo en cuenta la flexibilidad que define las alianzas estratégicas y la frecuencia de las terminaciones. Si bien es valioso saber por qué las empresas abandonan las alianzas, las organizaciones también deben entender las implicaciones de la terminación y cómo se relacionan con las condiciones que definen la alianza para abordar mejor las estrategias de colaboración. En consecuencia, el objetivo general de esta tesis doctoral es estudiar empíricamente las implicaciones de la terminación de una alianza desde la perspectiva de la organización. Para alcanzar este objetivo, se ha efectuado una recogida expansiva de datos sobre alianzas formadas entre 1990 y 2005 en el sector de las ciencias de la vida. El historial de las alianzas y sus terminaciones a lo largo de 2015 ha sido analizado a partir de notas de prensa de varias bases de datos. Además, la revisión de la literatura ha revelado que escasean las investigaciones empíricas sobre terminaciones que no correspondan a JV, así como la importancia de distinguir entre dos modos destacados de terminación: la disolución y la internalización (es decir, la adquisición tras la alianza), impulsado la incorporación de la gobernanza de las alianzas (JV-noJV) y del modo de terminación en todos los estudios. Dada la importancia de las alianzas para acceder a valiosos recursos externos (tácitos) y la reconfiguración de recursos inherentes a la terminación de las mismas, esta tesis se fundamenta en la concepción de la empresa basada en los recursos (RBV) y en el conocimiento (KBV). En concreto, se han desarrollado tres estudios con el fin de examinar los resultados organizativos relacionados con (1) el desempeño de la empresa, (2) la innovación y la construcción de conocimiento y (3) la necesidad de comprender la terminación de las alianzas por la vía de la internalización. Para comprender mejor las repercusiones sobre el desempeño de la empresa, en el primer estudio se ha utilizado el análisis de eventos y de regresión con el fin de examinar la relación existente entre el modo de terminación, el motivo del mismo, así como la gobernanza JV y la reacción del mercado ante el anuncio de la terminación. Los resultados demuestran que la disolución de la alianza tiene un efecto generalmente negativo sobre el valor de mercado de la empresa, mientras que la internalización de la alianza presenta unos coeficientes positivos, pero no significativos. La interacción significativa entre el modo de terminación de la alianza y el motivo de la terminación explica, además, que la internalización crea valor de mercado cuando la terminación viene motivada por el crecimiento y por una reestructuración, mientras que la disolución en estas condiciones tiene un efecto negativo. Los motivos de terminación relacionados con el desempeño y el aumento de las condiciones externas tienen un efecto negativo sobre el valor de la empresa en los dos modos de terminación, mientras que la gobernanza JV no influye en estas relaciones. En el segundo estudio, se analiza las repercusiones de la terminación de una alianza sobre la innovación y la construcción de conocimiento, aplicando el método DD y la estimación coincidente a una muestra de alianzas de I+D disueltas y no disueltas. Las conclusiones revelan que la terminación de una alianza reduce significativamente el desempeño de la innovación, que la construcción de conocimiento resulta menos diversa desde el punto de vista tecnológico y, contra todo pronóstico, menos orientada internamente tras la terminación. Sin embargo, los resultados no muestran un impacto significativo de la terminación en la construcción de conocimiento entre empresas, ni tampoco un efecto moderador de la gobernanza JV, la proximidad geográfica, las alianzas en el sector y la I+D interna. Por otro lado, el tamaño del portfolio de alianzas parece reducir significativamente el efecto negativo sobre el desempeño de la innovación, la diversidad tecnológica y la orientación interna. Con relación a los distintos efectos de la internalización de la alianza que se han evidenciado en el primer estudio y dadas las escasas investigaciones previas encontradas sobre el tema, el tercer estudio lleva a cabo una revisión sistemática de la internalización de la alianza para ofrecer una visión panorámica sobre la transición de las alianzas entre empresas a la organización interna. Esta revisión presenta un modelo de condiciones que guía la internalización de la alianza y analiza las evidencias de las implicaciones de la internalización sobre el desempeño. Además de las limitaciones del estudio, la tesis concluye con la discusión integrada de los resultados, sobre los que destaca la importancia del análisis de la terminación de las alianzas para el desarrollo de las teorías de la organización y la colaboración de forma más global.
Strategic alliance exit has drawn scholarly attention for decades. Since the inception of alliance research, studies have recognized the flexible and temporal character of interfirm agreements. Alliance exit constitutes an important phase of the alliance life cycle and a key activity in alliance portfolio restructuring. Previous research has largely focused on uncovering the motives for alliance exit while scarce research has examined the implications of exit. This is surprising given the frequency of exit and considering flexibility is a defining feature of alliances. While it is valuable to know why firms exit alliances, organizations also need to understand the implications of exit, and how they relate to alliance, exit, and firm conditions to better inform collaborative strategy. Accordingly, the overarching objective of this PhD Thesis is to empirically investigate alliance exit implications from an organizational level perspective. To achieve this objective, an expansive data collection effort was undertaken on alliances formed from 1990-2005 in the Life Science industry. Alliance histories and exits were tracked through 2015 using press releases from various databases. Additionally, literature reviews revealed a lack of empirical research on non-JV exit and the important distinction between two prominent exit modes: dissolution and internalization (i.e. post alliance acquisition), prompting the incorporation of JV governance and exit mode throughout the studies. Provided the importance of alliances for accessing valuable external (tacit) resources, and the resource reconfiguration inherent in alliance exit, this thesis builds predominantly on the resource-based and knowledge-based views of the firm. Specifically, three studies were conducted to examine organizational outcomes related to (1) firm performance, (2) innovation and knowledge building, and (3) to nuance the understanding of alliance exit via internalization. To better understand firm performance implications, the first study employs an event-study methodology and regression models to examine the relationship between exit modes, motives, and JV governance and the market reaction to alliance exit announcements. The results demonstrate that alliance dissolution has an overall negative effect on firm market value while alliance internalization shows positive but non-significant coefficients. A significant interaction between alliance exit mode and motives further explains that internalization creates market value when exit is motivated by growth and refocusing, while dissolution under these conditions has a negative effect. Exit motives related to performance issues and external conditions growth have a negative impact on firm value under both exit modes while JV governance did not influence these relationships. To study the innovation and knowledge-building implications of alliance exit, the second study applies a difference-in-differences and matching estimation to a sample of exited and non-exited R&D alliances. The findings reveal that alliance exit significantly reduces innovation performance, knowledge building becomes less technologically diverse, and unexpectedly, less internally oriented after exit. However, the results do not show a meaningful impact of exit on interfirm knowledge building, nor a moderating effect of JV governance, geographic proximity, same industry alliances, and internal R&D. To the contrary, alliance portfolio size is shown to significantly reduce the negative effect on innovation performance, technological diversity, and internal orientation. Related to the distinct effects of alliance internalization revealed in the first study and the scarce initial research found on the topic, the third study, a systematic review on alliance internalization, offers cumulative insight on the transition from interfirm alliance to internal organization. The review presents a model of conditions driving alliance internalization and discusses the evidence on the performance implication of internalization. The thesis concludes with an integrated discussion of the findings and limitations and highlights the importance of alliance exit for comprehensive organizational and collaboration theory.
Llewellyn, Sue. "Integrating professional and managerial expertise : shifting boundaries in UK health and social services." Thesis, University of Edinburgh, 2002. http://hdl.handle.net/1842/24848.
Full textWolfenden, Neil Martin. "Non-standard employment contracts in the IT sector : the shifting boundaries of control." Thesis, University of Leeds, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436455.
Full textMcDonough, Sara Megan. "Assessing Shifting Racial Boundaries: Racial Classification of Biracial Asian Children in the 2000 Census." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/36341.
Full textMaster of Science
Barabantseva, Elena. "Shifting boundaries of the Chinese nation : : Ethnic minorities and overseas Chinese in China's modernisation project." Thesis, University of Manchester, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488386.
Full textRohregger, Barbara A. [Verfasser]. "Shifting Boundaries : Social Security in the Urban Fringe of Lilongwe City, Malawi / Barbara A Rohregger." Aachen : Shaker, 2006. http://d-nb.info/1186583762/34.
Full textCrye, Jennifer L. "Shifting Boundaries: Rethinking the nature of religion and religious change among minority peoples in late imperial Russia." Oxford, Ohio : Miami University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1249395999.
Full textMoise, Valentina. "The shifting borders of EU expansion : everyday experiences of removing and replacing boundaries on the Italian-Slovenian border." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/the-shifting-borders-of-eu-expansioneveryday-experiences-of-removing-and-replacing-boundaries-on-the-italianslovenian-border(8ad76a02-d829-4dc5-a25a-086e4a35e27a).html.
Full textDee, Jason. "Out of body experiences : a practice-led evaluation of the shifting boundaries shared by analogue films and their digital counterparts." Thesis, University of Newcastle upon Tyne, 2015. http://hdl.handle.net/10443/2851.
Full textTrisyani, Yanny. "An exploration of the role of nurses working in emergency care services in general hospitals in Indonesia." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/96103/1/Yanny_Trisyani_Thesis.pdf.
Full textSardzoska, Natasa [Verfasser], and Reinhard [Akademischer Betreuer] Johler. "From shifting borders towards liminal boundaries : The nomadic capture of morphing contouring spaces in the artwork and lives of some expatriated former Yugoslavian artists and writers / Natasa Sardzoska ; Betreuer: Reinhard Johler." Tübingen : Universitätsbibliothek Tübingen, 2013. http://d-nb.info/1162444827/34.
Full textSardzoska, Natasa Verfasser], and Reinhard [Akademischer Betreuer] [Johler. "From shifting borders towards liminal boundaries : The nomadic capture of morphing contouring spaces in the artwork and lives of some expatriated former Yugoslavian artists and writers / Natasa Sardzoska ; Betreuer: Reinhard Johler." Tübingen : Universitätsbibliothek Tübingen, 2013. http://d-nb.info/1162444827/34.
Full textMiller, Paul McLean. "Shifting boundaries : an ontology of with-being." Phd thesis, 2007. http://hdl.handle.net/1885/148224.
Full textScamardo, Tara Marie. "Blurring boundaries: shifting perceptions of femininity in the context of the English Civil War." 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1799.
Full textHuang, Ya-Hung, and 黃雅鴻. "Multiple Boundaries as Palimpsests: The Shifting Landscapes of Native Land Rights in Taiwan." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/hnkwqs.
Full text國立東華大學
族群關係與文化學系
102
This study illustrates how activists of the Amis Indigenous nation in Taiwan, whose traditional lands are located in Karowa in Hualien County, have physically and politically embodied their views in order to rewrite boundaries in accordance with their rights to traditional lands. The research framework consists of three parts. The first part analyses Karowa Amis social movement strategies and develops an appropriate research methodology based on the views possessed by the Karowa people on their traditional lands. The second part situates the research in current geographical theories related to Indigenous traditional land rights. The final part explores the history of Taiwan's Indigenous traditional land rights movements and for comparative purposes examines native title settlement in South Australia. The study finds that through a combination of commodity economics and colonialism, sugar industry capitalists have developed near-exclusive power to inscribe repeatedly a variety of epistemological, aesthetic and symbolic tropes—based on their preference for economic gain—that have superimposed new mental and physical landscapes over Karowa Amis’ traditional lands. Even after the Indigenous Peoples Basic Law was implemented in 2005, Taiwan Sugar Corporation has continued to use various forms of afforestation in plains areas—such as the creation of Tanong-Tafu Forest Park—to construct landscapes inscribed with spatial discourses implying that Karowa lands are “terra nullius”, where Indigenous- peoples “don’t exist” or “have been assimilated”. These new boundaries purport that the lands belong to the State and are not traditional Indigenous territory. The implementation of the Indigenous Peoples Basic Law recognizes the possibility of restructuring rights and creating special land boundaries. This has inspired Taiwanese Indigenous nations attempting to transform power structures, using the new conditions of acknowledged rights. In this light, the experience of the Karowa Amis—as in other cases in Taiwan—illustrates that “tribal mapping” represents a truly significant watershed for the Taiwanese Indigenous land rights movement. Unfortunately, Indigenous cultures in Taiwan have lacked the opportunity to exercise their rights fully. The only basis for the legitimacy of their rights is the Indigenous Peoples Basic Law, which affirms their right to traditional use. However, the lack of territorial rights and autonomy renders difficult the full practice of these rights to use traditional lands in everyday life. Therefore, Indigenous peoples have been frustrated when attempting to exercise their rights under the Indigenous Peoples Basic Law, due to such hegemonic political structures. Reflecting on the native title settlement process in South Australia, we found that Taiwan lacks not only a constitutional, comprehensive settlement structure encompassing social, administrative and legislative aspects of State-Indigenous relations, but also a means of understanding how the process of settlement is dependent upon the practice of Indigenous autonomy. This research suggests the need to produce a variety of erasing and re-writing tools in legal systems, administration, education, symbols, and everyday life practices for the attainment of spatial decolonization. Legal reform is not the only way to promote Indigenous traditional land rights. We suggest that erasing and re-writing colonial territorial tropes will also help bring about the long-term recognition of Indigenous traditional land rights.
Triadafilopoulos, Triadafilos. "Shifting boundaries : immigration, citizenship, and the politics of national membership in Canada and Germany /." 2004. http://wwwlib.umi.com/dissertations/gateway.
Full textTypescript. Includes bibliographical references (leaves 329-367). Also available in electronic format on the World Wide Web. Access restricted to users affiliated with the licensed institutions.
Schouls, Timothy A. "Shifting boundaries : aboriginal identity, pluralist theory, and the politics of self-government in Canada." Thesis, 2002. http://hdl.handle.net/2429/13235.
Full textLiu, Guan-Wei, and 劉官維. "What is "Indie"? The Production and Shifting of Boundaries in the Independent Music Scenes." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/zyvbks.
Full text國立清華大學
社會學研究所
103
People have different opinions on the idea of indie music, and this dissertation starts with the various opinions, hoping to redefine and illustrate the complicity and the ambiguous boundary of Taiwanese indie music. In my observation, I discover that there are three elements of Taiwanese indie music, which are the “Do it yourself” (as known as DIY), the orientation of participating in social movement, and the orientation of intense nationalism. With these elements, they form the unique structure of Taiwanese indie music. Also, the complicity and the vividly recognized identity within Taiwanese indie music are further established through different interpretations and practices by different artists. In order to capture the complicity and the flexibility in the image of Taiwanese indie music, I use “identity boundary” as my methodology by interviewing ten groups of indie music artists, a total of 19 people, through in-depth interviews and focus group interviews about three questions. First, how is the identity boundary in Taiwanese indie music communities formed? Second, what is the indie music artists’ experience during the formation, the shift, and the ambiguity of boundary and how do they react to the gradually established nature and ideology of Taiwanese indie music? Last but not least, how could the indie music artists come up with the claim that “music can intervene the society” and how could they put it into practice? Therefore, the core of this dissertation lies in discussing the definition of indie music and the reaction of the indie music artists to the already defined images of indie music through their subjective point of view to examine how they fortify and deconstruct their ideas of indie music so that we can reunderstand and redefine the indie music. The ultimate answer for me is finding the reason why indie music is indie music. Finally, I find out that the identity of Taiwanese indie music relies on the local music environment, which means that the recognition and imagination of “guà” (a group of people with the same belief) have influence on the practice and the formation of music producing of the indie music artists. Therefore, the indie music evolved into different styles based on the understanding of “guà.” Furthermore, I believe that Taiwanese indie music artists’ interpretation of “authenticity” lies in the center of their own identity formation. Therefore, they can identify themselves from others through the process of reinterpreting and imagining the authenticity.
Iancu, Zohar. "Between the physical and the symbolic : on shifting of boundaries within the Israeli culture." Master's thesis, 2018. http://hdl.handle.net/10400.14/27122.
Full textBharathi, V. "Shifting boundaries of the self: Represenation of women in the fiction of Patrick White and Margaret Laurence." Thesis, 1993. http://hdl.handle.net/2009/1223.
Full textCompagnoni, Melissa. "Shifting the boundaries between science and art : a case study of an exhibition of science and art." Thesis, 2000. http://hdl.handle.net/1885/147931.
Full textEbert, Maximilian. "Shifting the boundaries of experimental studies in engineering enzymatic functions : combining the benefits of computational and experimental methods." Thèse, 2016. http://hdl.handle.net/1866/19025.
Full textL'industrie chimique mondiale est en pleine mutation, cherchant des solutions pour rendre la synthèse organique classique plus durable. Une telle solution consiste à passer de la catalyse chimique classique à la biocatalyse. Bien que les avantages des enzymes incluent leur stéréo, régio et chimiosélectivité, cette sélectivité réduit souvent leur promiscuité. Les efforts requis pour adapter la fonction enzymatique aux réactions désirées se sont révélés d'une efficacité modérée, de sorte que des méthodes rapides et rentables sont nécessaires pour générer des biocatalyseurs qui rendront la production chimique plus efficace. Dans l’ère de la bioinformatique et des outils de calcul pour soutenir l'ingénierie des enzymes, le développement rapide de nouvelles fonctions enzymatiques devient une réalité. Cette thèse commence par un examen des développements récents sur les outils de calcul pour l’ingénierie des enzymes. Ceci est suivi par un exemple de l’ingénierie des enzymes purement expérimental ainsi que de l’évolution des protéines. Nous avons exploré l’espace mutationnel d'une enzyme primitive, la dihydrofolate réductase R67 (DHFR R67), en utilisant l’ingénierie semi-rationnelle des protéines. La conception rationnelle d’une librarie de mutants, ou «Smart library design», impliquait l’association covalente de monomères de l’homotétramère DHFR R67 en dimères afin d’augmenter la diversité de la librairie d’enzymes mutées. Le criblage par activité enzymatique a révélé un fort biais pour le maintien de la séquence native dans un des protomères tout en tolérant une variation de séquence élevée pour le deuxième. Il est plausible que les protomères natifs procurent l’activité observée, de sorte que nos efforts pour modifier le site actif de la DHFR R67 peuvent n’avoir été que modérément fructueux. Les limites des méthodes expérimentales sont ensuite abordées par le développement d’outils qui facilitent la prédiction des points chauds mutationnels, c’est-à-dire les sites privilégiés à muter afin de moduler la fonction. Le développement de ces techniques est intensif en termes de calcul, car les protéines sont de grandes molécules complexes dans un environnement à base d’eau, l’un des solvants les plus difficiles à modéliser. Nous présentons l’identification rapide des points chauds mutationnels spécifiques au substrat en utilisant l'exemple d’une enzyme cytochrome P450 industriellement pertinente, la CYP102A1. En appliquant la technique de simulation de la dynamique moléculaire par la force de polarisation adaptative, ou «ABF», nous confirmons les points chauds mutationnels connus pour l’hydroxylation des acides gras tout en identifiant de nouveaux points chauds mutationnels. Nous prédisons également la conformation du substrat naturel, l’acide palmitique, dans le site actif et nous appliquons ces connaissances pour effectuer un criblage virtuel d'autres substrats de cette enzyme. Nous effectuons ensuite des simulations de dynamique moléculaire pour traiter l’impact potentiel de la dynamique des protéines sur la catalyse enzymatique, qui est le sujet de discussions animées entre les experts du domaine. Avec la disponibilité accrue de structures cristallines dans la banque de données de protéines (PDB), il devient clair qu’une seule structure de protéine n’est pas suffisante pour élucider la fonction enzymatique. Nous le démontrons en analysant quatre structures cristallines que nous avons obtenues d’une enzyme β-lactamase, parmi lesquelles un réarrangement important des résidus clés du site actif est observable. Nous avons réalisé de longues simulations de dynamique moléculaire pour générer un ensemble de structures suggérant que les structures cristallines ne reflètent pas nécessairement la conformation de plus basse énergie. Enfin, nous étudions la nécessité de compléter de manière informatisée un hémisphère où l’expérimental n’est actuellement pas possible, à savoir la prédiction de la migration des gaz dans les enzymes. À titre d'exemple, la réactivité des enzymes cytochrome P450 dépend de la disponibilité des molécules d’oxygène envers l’hème du site actif. Par le biais de simulations de la dynamique moléculaire de type Simulation Implicite du Ligand (ILS), nous dérivons le paysage de l’énergie libre de petites molécules neutres de gaz pour cartographier les canaux potentiels empruntés par les gaz dans les cytochromes P450 : CYP102A1 et CYP102A5. La comparaison pour les gaz CO, N2 et O2 suggère que ces enzymes évoluent vers l’exclusion du CO inhibiteur. De plus, nous prédisons que les canaux empruntés par les gaz sont distincts des canaux empruntés par le substrat connu et que ces canaux peuvent donc être modifiés indépendamment les uns des autres.
The chemical industry worldwide is at a turning point, seeking solutions to make classical organic synthesis more sustainable. One such solution is to shift from classical catalysis to biocatalysis. Although the advantages of enzymes include their stereo-, regio-, and chemoselectivity, their selectivity often reduces versatility. Past efforts to tailor enzymatic function towards desired reactions have met with moderate effectiveness, such that fast and cost-effective methods are in demand to generate biocatalysts that will render the production of fine and bulk chemical production more benign. In the wake of bioinformatics and computational tools to support enzyme engineering, the fast development of new enzyme functions is becoming a reality. This thesis begins with a review of recent developments on computational tools for enzyme engineering. This is followed by an example of purely experimental enzyme engineering and protein evolution. We explored the mutational space of a primitive enzyme, the R67 dihydrofolate reductase (DHFR), using semi-rational protein engineering. ‘Smart library design’ involved fusing monomers of the homotetrameric R67 DHFR into dimers, to increase the diversity in the resulting mutated enzyme libraries. Activity-based screening revealed a strong bias for maintenance of the native sequence in one protomer with tolerance for high sequence variation in the second. It is plausible that the native protomers procure the observed activity, such that our efforts to modify the enzyme active site may have been only moderately fruitful. The limitations of experimental methods are then addressed by developing tools that facilitate computational mutational hotspot prediction. Developing these techniques is computationally intensive, as proteins are large molecular objects and work in aqueous media, one of the most complex solvents to model. We present the rapid, substrate-specific identification of mutational hotspots using the example of the industrially relevant P450 cytochrome CYP102A1. Applying the adaptive biasing force (ABF) molecular dynamics simulation technique, we confirm the known mutational hotspots for fatty acid hydroxylation and identify a new one. We also predict a catalytic binding pose for the natural substrate, palmitic acid, and apply that knowledge to perform virtual screening for further substrates for this enzyme. We then perform molecular dynamics simulations to address the potential impact of protein dynamics on enzyme catalysis, which is the topic of heated discussions among experts in the field. With the availability of more crystal structures in the Protein Data Bank, it is becoming clear that a single protein structure is not sufficient to elucidate enzyme function. We demonstrate this by analyzing four crystal structures we obtained of a β-lactamase enzyme, among which a striking rearrangement of key active site residues was observed. We performed long molecular dynamics simulations to generate a structural ensemble that suggests that crystal structures do not necessarily reflect the conformation of lowest energy. Finally, we address the need to computationally complement an area where experimentation is not currently possible, namely the prediction of gas migration into enzymes. As an example, the reactivity of P450 cytochrome enzymes depends on the availability of molecular oxygen at the active-site heme. Using the Implicit Ligand Sampling (ILS) molecular dynamics simulation technique, we derive the free energy landscape of small neutral gas molecules to map potential gas channels in cytochrome P450 CYP102A1 and CYP102A5. Comparison of CO, N2 and O2 suggests that those enzymes evolved towards exclusion of the inhibiting CO. In addition, we predict that gas channels are distinct from known substrate channels and therefore can be engineered independently from one another.
Keating, Erin M. ""My masculine part" : or, The disappearance of the female body : the shifting boundaries between gender, status, and the body in the writing of Aphra Behn." Thesis, 2006. http://spectrum.library.concordia.ca/8995/1/MR20665.pdf.
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