911 |
Uma análise exploratória de barreiras na implementação do plano de mobilidade urbana nas cidades de pequeno e médio porte no estado de São Paulo /Santos, Ana Laura Lordelo dos. January 2017 (has links)
Orientador: Bárbara Stolte Bezerra / Banca: Archimedes Azevedo Raia Junior / Banca: Gustavo Garcia Manzato / Resumo: O presente estudo objetiva contribuir com a promoção de uma mobilidade sustentável através da identificação das principais barreiras que dificultam a implementação dos Planos de Mobilidade Urbana (PMU), e m conformidade com a Lei n.12.587/2012, retardando o alcance e evolução de cidades mais sustentáveis e acessíveis. Tal identificação pode apoiar o planejamento estratégico através de informações objetivas que podem ser usadas para aconselhar políticos e de mais partes interessadas na promoção da mobilidade urbana sustentável nas cidades de pequeno e médio porte do Estado de São Paulo. Para responder esta questão foi utilizada uma pesquisa exploratória e quantitativa. A coleta de dados foi realizada através d o procedimento do tipo survey, utilizando um questionário semiestruturado enviado aos gestores públicos de cidades de pequeno e médio porte responsáveis pela mobilidade urbana, bem como para especialistas sobre o tema. Houve diferenças entre a percepção de barreiras entre os municípios de pequeno e médio porte, bem como entre os municípios e os especialistas. Para os municípios as principais barreiras encontram - se nas barreiras de recursos e nas barreiras sociais e culturais, já para os especialistas as bar reiras práticas e tecnológicas e as barreiras institucionais e políticas foram as mais relevantes. Na barreira de recursos foram apontadas limitações orçamentárias para investir em sistemas de transportes mais sustentáveis, limitações orçamentárias para a impleme... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The present study aims to contribute to the promotion of sustainable mobility by identifying the barriers that are an impediment for Urban Mobility Plans (UMP) implementation in accordance with Law no. 1287//2012, delaying the achieve ment and evolution of more sustainable and acce ssible cities. Thus, aim to support strategic planning through objective information that can be used to advise politicians and other interested parties in the promotion of sustainable urban mobility in the small and medium - sized cities of the State of São Paulo. To answer this question it was used an exploratory and quantitative analysis and the data collection was performed through the survey procedure using a semi - structured questionnaire, which was sent to public managers of small and medium - sized citie s, as well as experts on the subject. There were differences between the perception of barriers between small and medium sized municipalities, as well as between municipalities and specialists. For municipalities, the main barriers are found in resource ba rriers and in social and cultural barriers, while for practitioners, practical and technological barriers and institutional and political barriers were the most relevant. In the resource barrier, there were budgetary constraints to invest in more sustainab le transport systems, budget constraints for the implementation of the proposed measures, as well as the insufficient transfer of funds from the federal government to urban mobility. ... (Complete abstract click electronic access below) / Mestre
|
912 |
Aasenîkon! : Makushi travelogues from the borderlands of Southern GuyanaGrund, Lisa Katharina January 2017 (has links)
This ethnographic account focuses on the conceptions and practices of movement, as narrated by the Makushi people who live along the triple frontier of southern Guyana. The journeys - individual experiences, in particular of women – depict visits to other Makushi communities, to their neighbours and cities in Guyana, Brazil and Venezuela. The travelogues disclose Makushi premises on knowledge and its acquisition: gender, age, temporality and alterity. Exploring these concepts in practice, the ethnography points out the value the Makushi attribute to their encounters with others, situations in which risk and unpredictability are creatively incorporated as part of their sociality.
|
913 |
Understanding Housekeeper's Perceived Labor Mobility and Job Satisfaction within the Hospitality Industry in Metropolitan Phoenix, Arizona, U.S.A.January 2011 (has links)
abstract: The objective of this study was to understand domestic and foreign-born housekeeper's individual perceptions of labor mobility and job satisfaction related to their jobs within the hospitality industry. Literature regarding the bridging of tourism, immigration, and labor supply was addressed to expose broad conceptual frameworks that lead to the development of this study. More specifically, literature regarding labor mobility within tourism industries, migrant decision making, and barriers to mobility and immigration helped to construct a narrowed conceptual framework specific to hospitality labor in Phoenix, Arizona. Similar and previous studies focused on perceived labor mobility during significant economic or industry shifts. This study included the addition of a policy factor to help determine to what degree state policy change effected hospitality workers' perceived labor mobility. Arizona's recently passed and implemented legislative act SB1070 regards immigrant identification and employment, and enforcement of the act in the state of Arizona; this serves as the implicated policy change. Data were collected via on-site survey administered February to May 2011. An overall score was created for the five motivational dimensions: 1 — Status; 2 — Economic; 3 — Refugee; 4 — Entrepreneurial; and, 5 — Political using principle component factor analysis using a varimax rotation with Kaiser normalization. Theory and literature suggest that the economic advancement, status advancement, and the refugee orientation are effective explanatory variables for motivating a career move into the tourism industry. A total of 82 questionnaires were delivered and completed (N = 82), and none were eliminated. The statistically-determined Economic Dimension was characterized by eleven statements explained 51% of the variation and was the overwhelming motivational force. The average coded response for change in job satisfaction was very positive at .75. Ten features of changes in job satisfaction were used as the basis of the second measure of change in job satisfaction. The first Principle Component of the ten features of job satisfaction change explained 45% of the variation in these features and loadings were positive near or above 0.60 for all items. The relationship between variations in each of the measurements of change in job satisfaction and motivating factors was explored using regression analysis. The two dependent variables were Overall Change and First Principle Component, and the independent variables for both regressions included the four motivating factors as measured by the rotated factors scores to represent dimensions of Economic, Status, Refugee and Entrepreneurial. In addition to the motivational factors, four demographic variables were included as independent variables to account for personal and situational differences. None of the regression coefficients were significant at even the 10% level. Although this result was expected, the positive sign of regression coefficients suggest that expectations of working as a housekeepers results in a positive outcome. Understanding this relationship further is necessary, and seeking larger sample sizes over a longer period of time would be most beneficial to this field of research. / Dissertation/Thesis / M.S. Recreation and Tourism Studies 2011
|
914 |
Mobilidade funcional em idosos: influência de parâmetros musculares e de treinamentoGuadagnin, Eliane Celina January 2018 (has links)
A manutenção da qualidade de vida e da independência dos idosos está diretamente relacionada com a funcionalidade, a qual depende da estrutura e função do sistema musculoesquelético. Entender a relação entre parâmetros musculares e a funcionalidade em idosos possibilita delinear programas de treinamento adequados para prolongar a independência funcional dessa população. Nesse sentido, estudos mostram que o treinamento de força leva a ganhos de estrutura e função muscular, e de funcionalidade. Tarefas funcionais são realizadas utilizando diferentes tipos de contrações musculares. Porém, na literatura não há um consenso sobre a relação entre os parâmetros musculares e a funcionalidade em idosos, nem os efeitos de treinamentos de força utilizando diferentes tipos de contrações sobre a estrutura e função musculares, e a funcionalidade. Assim, o presente estudo teve como objetivos (1) identificar quais parâmetros estruturais e de função muscular de membros inferiores apresentam melhor relação e podem explicar o desempenho em tarefas funcionais; (2) revisar sistematicamente a literatura quanto aos efeitos de treinos com diferentes tipos de contrações para idosos; e (3) investigar os efeitos de um treinamento de força concêntrico versus um treinamento concêntrico-excêntrico para a musculatura flexora e extensora do joelho sobre parâmetros de estrutura e função muscular e funcionalidade de homens idosos. Para atingir esses objetivos, a presente tese foi dividida em quatro capítulos. No Capítulo 1, verificou-se a relação entre parâmetros de estrutura e função muscular de membros inferiores (arquitetura muscular, eco intensidade e força isométrica) e parâmetros funcionais (testes Timed Up and Go e sentar-e-levantar, marcha no solo e marcha com transposição de obstáculo em velocidade preferida e máxima). No Capítulo 2, investigou-se parâmetros estruturais e de função muscular de flexores e extensores de joelho (torque isométrico, concêntrico e excêntrico, potência, taxa de produção de força, eco intensidade e arquitetura muscular), considerando, assim, além dos parâmetros investigados no Capítulo 1, parâmetros de força dinâmica e os relacionando com diferentes testes funcionais (sentar-e-levantar, Timed Up and Go, equilíbrio, velocidade de marcha, caminhada de seis minutos, subida e descida de degraus e salto vertical). Os principais achados desses estudos demonstram que a estrutura dos músculos vasto lateral e tibial anterior, e o torque concêntrico de extensores de joelho foram os parâmetros com melhor relação com a funcionalidade. Para verificar a influência do treino de força com diferentes tipos de contração sobre parâmetros de estrutura e função muscular e funcionalidade, no Capítulo 3 realizou-se uma revisão sistemática de estudos envolvendo treinamento de força isocinética para membros inferiores em idosos. Verificamos que tanto o treino de força concêntrico quanto o excêntrico apresentam efeitos positivos sobre a função muscular e a funcionalidade. Porém, a capacidade funcional foi investigada em apenas um estudo, e a estrutura muscular em nenhum deles. Além disso, nenhum dos estudos realizou um treino combinando diferentes tipos de contração, o que poderia ser mais benéfico para os idosos. Portanto, no Capítulo 4 são apresentados dados preliminares do estudo envolvendo treinamento de força para homens idosos, onde um grupo realizou treinamento exclusivamente concêntrico e outro treino concêntrico-excêntrico para flexores e extensores de joelho. Os indivíduos foram avaliados quanto aos mesmos parâmetros do Capítulo 2 em três momentos: basal, duas semanas após a avaliação basal e ao final do treinamento. Os dados preliminares demonstram que ambos os grupos de treino apresentaram ganhos tanto musculares quanto funcionais após o treinamento. / Aging with quality of life is the biggest challenge for the elderly. Quality of life and independence maintenance are directly related to functionality, which depends on the musculoskeletal system structure and function. Understanding the relationship between muscular parameters and functionality in the elderly allows designing appropriate training programs to prolong this population’s functional independence. In this sense, studies show that the strength training lead to muscle structure and function and functionality gains. Functional tasks are performed utilizing different types of muscle contraction. However, there is no a consensus in the literature considering the relationship between muscle parameters and functionality in the elderly, nor considering the effects of strength trainings utilizing different contraction types on muscle’s structure and function, and on functionality. Thus, the present study had as objectives (1) to identify which lower limbs structural and muscular function parameters present better relation and can explain performance in functional tasks, (2) systematically review the literature about the effects of trainings with different contraction types for older subjects, and (3) to investigate the effects of concentric strength training versus concentric-eccentric training for knee flexors and extensors muscles on parameters of muscle structure and function and functionality in the elderly. To achieve these objectives, this thesis was divided into four chapters. In Chapter 1, the relationship between structural parameters and lower limb muscle function (muscular architecture, echo intensity and isometric strength) and functional parameters (Timed Up and Go and sit-to-stand tests, gait with and without obstacles at the preferred and maximum speed) was verified. In Chapter 2, the relationship between knee flexors and extensors structural parameters and muscle function (isometric, concentric and eccentric torque, power, rate of force production, echo intensity and muscular architecture) and functionality (sit-to-stand, Timed Up and Go, balance, walking speed, six-minute walk test, stair ascent and descent, and vertical jump) was investigated, considering, in addition to the parameters investigated in the Chapter 1, parameters of dynamic strength. The main findings demonstrate that the vastus lateralis and tibialis anterior muscles structure, and the knee extensor concentric torque were the parameters with better relation with functionality. In order to verify the influence of the strength training with different types of contractions on parameters of structure and muscular function and functionality, a systematic review of studies involving lower limb strength training in the elderly, performed on isokinetic dynamometers, was carried out in Chapter 3. We found that both concentric and eccentric strength training have positive effects on muscle function and functionality. However, functional capacity was investigated in only one study, while muscle structure in none of them. In addition, no studies performed a strength training combining different types of contraction, which could be more beneficial for older individuals. Therefore, Chapter 4 presents preliminary data from the study involving strength training for elderly men where one group performed exclusively concentric training and another concentric-eccentric training for knee flexors and extensors. Subjects were assessed for the same parameters of Chapter 2 at three different times: baseline, two weeks after baseline assessment and after training. Preliminary results indicate that both groups presented muscular and functional gains after the training period.
|
915 |
Carbon emissions of retail channels: the limits of available policy instruments to achieve absolute reductionsSeebauer, Sebastian, Kulmer, Veronika, Bruckner, Martin, Winkler, Eva 09 1900 (has links) (PDF)
Buying the same product at the neighborhood store or at a shopping mall implies different carbon emissions. This paper quantifies carbon impacts of consumer choices of retail channel and shop location (where to buy), extending footprint assessments of product choices (what to buy). Carbon emissions of shopping situations are shown in the current situation, in a business-as-usual projection in 2020, and in policy scenarios with changed market shares of shopping situations. The analysis covers the product categories: groceries, clothing, and electronics & computers, from the shopping situations: neighborhood store, town center, discount store, shopping mall, and mail order/online selling. Stages of the product life cycle which differ between shopping situations are examined: freight transport, warehousing, store operation, and the last mile of the consumers' trip to the store. Carbon emissions of shopping situations amount to 2.7% of overall Austrian emissions in the base year. Dominant car use on the last mile substantially contributes to the overall footprint. In the business-as-usual scenario, carbon emissions from shopping situations increase by +33% until 2020, corresponding to 4.2% of the overall Austrian emissions target for 2020. Restricting shopping malls or supporting neighborhood stores could limit this increase to +25% and +20%, respectively. Facilitating online selling achieves no notable effects. The study underlines that an absolute reduction in private demand for household goods is necessary, as available policy instruments aiming at shopping situations fail to compensate the steady growth in private consumption.
|
916 |
Rôle du vidéo streaming mobile qui dépend du contexte dans l'amélioration de la qualité d'expérience / Impact of mobility on QoE in wireless networksTriki, Imen 05 June 2018 (has links)
L'utilisation répandue des smartphones dans notre vie quotidienne et l'essor technologique que connait le monde aujourd'hui -offrant l'accès mobile à très haut débit- ont exponentiellement augmenté la demande sur les services de vidéo streaming mobile, ce qui justifie la tendance à explorer de nouvelles approches pour la distribution des contenus média. Afin d'assurer une qualité de streaming constante et acceptable, la majorité des approches proposent aujourd'hui d'adapter la distribution des flux média au contexte de l'utilisateur. Dans le but de garder l'utilisateur le plus longtemps connecté à sa session de streaming, ces approches s'intéressent plus particulièrement à l'amélioration de sa perception de la vidéo. Ce qui justifie l'intérêt croissant accordé à l'étude la qualité d'expérience (QoE). Pour assurer une bonne QoE, les solutions de vidéo streaming mobile exigent la connaissance au préalable du contexte de l'utilisateur, comme par exemple la capacité de son lien physique ou la disponibilité de sa bande passante. L'acquisition de telles informations contextuelles est devenue possible aujourd'hui grâce à l'utilisation des capteurs sans fils dans les appareils mobiles et à l'existence de plusieurs applications intelligentes dédiées, le principe étant majoritairement d'exploiter la forte corrélation entre le contexte de l'utilisateur et sa position géographique. Pour faciliter l'étude du contexte de l'utilisateur, plusieurs cartes radio ont été conçues, permettant le traçage spatio-temporel des caractéristiques radio comme par exemple le débit moyen ou la force moyenne du signal. En outre, plusieurs études menées sur les modèles de mobilité des usagers ont exhibé une quasi-régularité spatio-temporelle dans leurs trajets quotidiens, soit en prenant les transports publics ou en allant vers des endroits fréquemment visités. Couplés avec les cartes radio, ces études permettent une haute précision dans la prédiction du contexte de l'utilisateur le long de son trajet. Dans cette thèse, nous nous intéressons à analyser l'impact de l'adaptation du service vidéo streaming au contexte de l'utilisateur sur sa QoE finale. Nous commençons par proposer CAMS (Context Aware Mode Switching), un mécanisme d'allocation de ressources qui dépend du contexte et qui s'applique à la distribution du vidéo streaming réel (non-adaptatif), pour assurer le minimum d'interruptions de vidéo. CAMS est conçu pour être déployé dans une topologie de réseau spécifique avec un modèle de mobilité particulier. Par la suite, nous explorons l'impact de la connaissance à l'avance du débit futur de l'utilisateur sur l'adaptation de la qualité de sa vidéo et sur le coût de sa transmission dans un contexte de streaming adaptatif. Nous proposons NEWCAST (aNticipating qoE With threshold sCheme And aScending biTrate levels), un algorithme proactif pour l'ajustement du coût et l'adaptation de la qualité sous réserve d'une prédiction parfaite du débit. Nous étendons cette étude, dans un deuxième temps, pour le cas où la prédiction du débit est imparfaite. Nous proposons, donc, d'autres algorithmes adaptatifs en nous inspirant de l'approche de NEWCAST. Pour étudier la faisabilité de ces algorithmes sur le plan pratique, nous menons quelques expérimentations dans un environnement émulé à l'aide du lecteur média DASH-IF-Reference. Finalement, nous explorons l'idée de coupler la connaissance parfaite du débit futur de l'utilisateur avec l'usage d'un mécanisme d'apprentissage automatique, pour améliorer la QoE dans un contexte de streaming adaptatif. Nous proposons, donc, un système à boucle fermée, basé sur le retour des utilisateurs, pour apprendre progressivement leurs préférences et pour optimiser adéquatement la transmission des futures vidéos. Ce système est particulièrement conçu pour être utilisé dans des populations hétérogènes avec des profils de QoE différents et inconnus à l'avance. / The strong emergence of smartphones on human daily life as well as the highbroadband access supplied by operators have triggered pervasive demand on videostreaming mobile services, requiring the exploration of novel approaches on videocontent delivery. To afford video streaming services at sustainable quality, the idea of adjusting the streaming to the time-varying users’ contexts has been actively investigatedduring the recent years. Since the users’ perceptions on the video qualitydirectly impact their engagement in video streaming sessions, many interests havebeen accorded to the user’s Quality of Experience (QoE).Today streaming solutions mostly rely on the user’s contextual information suchas his link capacity or his available bandwidth to provide an acceptable final QoE.Such contextual information can be easily acquired thanks to the existence of wirelesssensors and dedicated smart applications on today mobile devices. At the core, liesthe idea of exploiting the strong correlation between users’ locations and contexts. Tothat end, radio maps with historical average signal strength have been geographicallymapped. Various studies on users’ mobility patterns also showed that people dailyroutes exhibit a high degree of spatial and temporal regularity, especially on publictransportation or on road ways to/from frequently visited places. Coupled with radiomaps, these mobility patterns can give high accuracy on context predictability alongusers’ trips.In this thesis, we analyse the impact of adapting video streaming to the user’scontext on the final QoE.We start by proposing CAMS (Context Aware Mode Switching),a context-aware resource allocation mechanism, for real (i.e, non adaptive) videostreaming delivery to reduce the number of video stalling. CAMS is designed to beapplied in a particular network topology under a particular mobility of users. Then,we explore the impact of knowing the future throughput variations on video quality adaptation and delivery cost in adaptive video streaming. We propose NEWCAST(aNticipating qoE With threshold sCheme And aScending biTrate levels) as a proactivealgorithm for cost adjustment and quality adaptation under the assumption of aperfect throughput estimation. We then extend the study to the case where throughputprediction errors may exist and propose a bench of adaptive algorithms inspiredfrom NEWCAST. To explore the feasibility of implementing these algorithms in realworld streaming, we conduct some experiments with the DASH-If Reference playerin an emulated environment. Finally, we explore the impact of knowing the futurethroughput variations when exploited with machine learning on the global QoE enhancementin adaptive video streaming. We propose a closed-loop framework basedon users’ feedbacks to progressively learn their QoE profiles and to fittingly optimizevideo deliveries. This framework is in particular suited for heterogenous populationswhere the QoE profiles of users are quite different and unknown in advance.
|
917 |
Land use, job accessibility and commuting efficiency under the hukou system in urban China: a case study in GuangzhouLiu, Yi 22 June 2017 (has links)
Job-housing relations, job accessibility and commuting efficiency have been the concerns of academics and policy makers alike, and a large body of literature has been published on relevant topics. Although various hypotheses from the West have been tested in research on some Chinese major cities, most neglects the role of the hukou system, the most essential and unique institution influencing every aspect of people's daily life in China. This thesis responds to this deficiency by placing hukou at the forefront in the analysis of job-housing relations and commute. The data used in this thesis is from a household survey in Guangzhou as well as the population and economic census. Firstly, it analyses the job-housing relationship and commuting patterns in Guangzhou as well as the influence of hukou system. Secondly, it examines the spatial pattern of job accessibility in Guangzhou and accessibility inequality between local and non-local hukou holders. Also, the differential influences of land use and mobility on different hukou holders' job accessibility are evaluated. Thirdly, it estimates and compares the commuting efficiency of Guangzhou with other cities, and evaluates the roles of hukou system and other socio-economic factors in the commuting efficiency of Guangzhou. Meanwhile, the present research highlights the mechanism underlying the interactions between hukou system, job-housing relations and commute, and discusses the influences of hukou system on job/housing market and public services/welfare provisions. Taking hukou into consideration, this thesis contributes to the fields of jobs-housing relationship and commute in urban China by addressing the complex influences of local context on job-housing relations and commute as well as providing a mapping of inequalities between different hukou holders.
|
918 |
Quality of life and depressive symptoms as predictors of participant adherence in a randomized trial conducted among older adults at risk of mobility disabilityZhu, Hao 12 March 2016 (has links)
Poor adherence is an issue in clinical trials with a striking magnitude and negative impact. Recent studies indicate that two widely used clinical screening tools, Short Form (SF-36) Health Survey and Center for Epidemiologic Studies Depression Scale (CES-D) can be used as risk stratifiers to identify participants who require extra interaction to stay adherent in specific population. There is, however, little evidence to support the implication of these tools in elderly individuals with mobility limitations. These individuals may be particularly vulnerable to the risks of poor adherence in the context of a demanding interventional scheme. This study fulfills this gap by analyzing the quality of life and adherence data from the VIVE2 study, which is a double-blinded randomized explanatory clinical trial assessing the benefits of nutritional supplements and daily exercises to elderly patients with mobility limitation. The preliminary results showed that in clinical studies targeting elderly population with mobility limitations, the summary scores of SF-36 trended to have weak and nonsignificant association with a decreased risk of poor adherence to both exercise completion and product consumption while CES-D has no association.
|
919 |
Studies of macromolecular trafficking across Arabidopsis homograftsPaultre, Danaé Simone Genevieve January 2017 (has links)
Micrografting was used to study the restoration of symplasmic transport at the graft union and to examine the long-distance transport of macromolecules between scion and rootstock. New techniques were established, such as correlative imaging and single-cell analysis in microfluidic devices, to study graft development both in vivo and in vitro. Imaging of Arabidopsis homografts showed that a symplasmic domain develops in the callus stele whose function may be to contain the spread of auxin into the surrounding ground tissue. It was demonstrated, also, that recent reports of organelle transfer at the graft union cannot be explained by the formation of secondary plasmodesmata (PD) at the graft interface. While fused calli did not exchange organelles in vitro, large aggregates of the SIEVE-ELEMENT OCCLUSION RELATED protein fused to YFP (SEOR-YFP; 112 kDa) were unloaded from mature sieve tubes into living cells of the graft partner in vivo, suggesting that vascular remodelling may be a prerequisite for the exchange of organelles at the graft interface. Fusion proteins expressing organelle-targeting signals were found to translocate across the graft junction, unloading into cell files adjacent to the root protophloem. The phloem mobility of a given fusion protein was assessed using bioinformatic and statistical analysis of publicly available data. The size of a protein and its relative abundance in CCs both emerged as defining factors for subsequent phloem transport. The recipient tissue for phloem-unloaded macromolecules was identified as the phloem-pole pericycle (PPP). This cell layer is required to remove macromolecules from the terminus of the protophloem. Induced callose deposition at the PD that connect protophloem SEs to the PPP caused a restriction in unloading and a subsequent arrest in root growth. A non-cell autonomous protein of CC origin, NaKR1-1, is proposed to affect the unloading of macromolecules either by increasing the size exclusion limit (SEL) of PD within the PPP or by enabling a build-up in pressure at the protophloem terminus, due to SUC2 activity, thus allowing phloem unloading.
|
920 |
Investigation of large protein and multimeric protein complex structures with mass spectrometry techniquesPacholarz, Kamila Jolanta January 2015 (has links)
The biophysical properties, biological activity and function of macromolecular systems are highly dependent on their structure. Structure-activity relationships of proteins and their binding partners are critical for drug discovery, biochemical and medical research. While the gas-phase environment might present as an unusual venue from which to explore protein structure, for over the past two decades, nano-electrospray ionization (nESI) coupled to mass spectrometry (MS) has been recognized as having great potential for analysis of protein structure and protein non-covalent complexes. In conjunction with related technique of ion mobility (IM), mass spectrometry (IM-MS) provides insights into protein native-like conformations and any structural changes in may undergo upon ligand binding or alternations induced via physical parameters such as temperature, pressure or solution conditions. As most proteins tend to exist as multiple domains; from the distribution of oligomeric states in the Protein Data Base (PDB) 86% of proteins exist as oligomers; the work presented in this thesis focuses on application of MS techniques to probe the tertiary and quaternary structure of various large and multimeric protein complexes, their dynamics and/or conformational changes. Wherever relevant, the gas-phase studies reported here are complemented by other techniques, such as hydrogen deuterium exchange MS (HDX), molecular modelling (MD) and analytical ultracentrifugation (AUC). Firstly, the dynamics of intact monoclonal antibodies (mAbs) and their fragments are explored with IM-MS. Variations observed in conformational landscapes occupied by two mAb isotypes are rationalized by differences in disulfide linkages and non-covalent interactions between the antibody peptide chains. Moreover, mAb intrinsic flexibility is compared to other multimeric protein complexes in terms of collision cross section distribution span. Secondly, variable temperature MS (VT-MS) and variable temperature IM-MS (IM-MS) are used to probe unfolding and dissociation of four standard multimeric protein complexes (TTR, avidin, conA and SAP) as a function of the of analysis environment temperature. VT-MS is found to allow for decoupling of their melting temperature (Tm) from the protein complex dissociation temperature (TGPD). Whereas, VT-IM-MS is used to investigate structural changes of these protein complexes at elevated temperatures and provide insights into the thermally induced dissociation (TID) mechanism, as well as strength of the non-covalent interactions between subunits. Thirdly, VT-(IM)-MS methodology is applied to study behaviour of three mAbs: IgG1, IgG4 and an engineered IgG4 of increased thermal stability. Such analysis shows to be promising for comparative thermal stability studies for proteins of therapeutic interest. Lastly, the structure of ATP-phosphoribosyltransferase (MtATPPRT), an enzyme catalysing the first step of the biosynthesis of L-histidine in Mycobacterium tuberculosis, is explored. Conformational changes occurring upon feedback allosteric inhibition by L-histidine are probed with MS, IM-MS, HDX-MS and AUC. Reported results serve as the basis for IM-MS/HDX-MS based screening method to be used for screening of a library of novel and promising anti-tuberculosis agents.
|
Page generated in 0.0712 seconds