Biophysical studies of membrane proteins/peptides. Interaction with ...

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Finalmente, a agregação de fosfoinositol-4,5-bisfosfato (PI(4,5)P 2 ) em bicamadas de fosfocolinas foi estudada (Capítulo VI), de forma a testar a hipótese de agregação espontânea deste lípido numa matriz de fosfocolinas. Os resultados de extinção de fluorescência colisional obtidos com um derivado de PI(4,5)P 2 marcado com uma sonda fluorescente e de um estudo de FRET utilizando este lípido derivatizado como dador para uma sonda distribuida homogeneamente na membrana, são inequívocos na confirmação de uma distribuição homogénea de PI(4,5)P 2 na bicamada lipídica. No mesmo estudo, é demonstrado que a diferentes estados de protonação de PI(4,5)P 2 correspondem diferentes eficiências de partição para o ambiente lipídico, um fenómeno que pode apresentar relevância biológica significativa.
OUTLINE OUTLINE The last two decades, through a massive collective effort, allowed some insight into the nature of the interactions between the components of biomembranes and also the highly relevant biological consequences of these interactions. The Singer-Nicolson fluid mosaic model for biomembranes (1972), described a system where lipids were little else than a matrix where proteins were dispersed. The picture currently accepted is much more complex. Not only protein-protein interactions can be responsible for mediation of cellular functions, but also protein-lipid interactions are much more complex and important than originally thought. Detailed biophysical studies such as the ones described here, allow gathering of valuable information regarding the character of such interactions. Biomembranes delineate the boundaries of cellular life. They allow the differentiation of molecular environments through the control of permeability, creating the conditions for specialization within the cell. This task demands the expenditure of a massive amount of energy, emphasizing the dramatic importance of biomembranes. The foremost structural framework of biomembranes is the lipid bilayer, but lipids are far from being a homogeneous class of molecules. When the energies of interaction between lipid molecules are significantly different, large scale phase separation of lipid molecules in the membrane can occur, and even for small differences in lipid-lipid interaction energies, short-range heterogeneities are expected. Therefore, the lateral distribution of a multicomponent lipid bilayer is often heterogeneous. This portrait of biomembranes is made even more complex by the notion that lipids are not the only components found there. In fact, biomembranes are a mixture of different classes of molecules with different functions. Apart from lipids, the most notable component are proteins, which are highly concentrated in biomembranes and are largely responsible for the cellular functions operated there. Interactions between these quite different molecular species are very complex. Hydrogen bonds, electrostatic, and van der Waals forces, all operate simultaneously in dictating the equilibrium packing of proteins and lipids in bilayers. Notably, proteins and lipids will arrange in such a manner that their hydrophobic domains are shielded from the aqueous environment in order to prevent the entropy loss resulting from interaction with water molecules. As a consequence, membrane proteins and lipids will xxi
Page 1: UNIVERSIDADE TÉCNICA DE LISBOA INS
Page 4 and 5: Fernandes, F., Loura, L. M. S., Fed
Page 6 and 7: Ao Pedro e Hugo, amigos de longa da
Page 8 and 9: 2.2. - Peptides as models 2.3. - Am
Page 11 and 12: ABBREVIATIONS AND SYMBOL LIST ABBRE
Page 13: RESUMO RESUMO As biomembranas são
Page 17 and 18: SINOPSE SINOPSE Nas últimas duas d
Page 19 and 20: SINOPSE podem fornecer informação
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Page 25 and 26: OUTLINE membranes with a distributi
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In Figure I.21, theoretical simulat
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PROTEIN-PROTEIN AND PROTEIN-LIPID I
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2430 Biophysical Journal Volume 85
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2432 Fernandes et al. Coat protein
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2434 Fernandes et al. leads to an a
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2436 Fernandes et al. FIGURE 4 (A)
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2438 Fernandes et al. section of th
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2440 Fernandes et al. tein oligomer
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QUANTIFICATION OF PROTEIN-LIPID SEL
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FRET Study of Protein-Lipid Selecti
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BINDING OF INHIBITORS TO A PUTATIVE
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BINDING OF INHIBITORS TO A PUTATIVE
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INTERACTION OF THE INDOLE CLASS OF
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5272 Biochemistry, Vol. 45, No. 16,
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BINDING ASSAYS OF INHIBITORS TOWARD
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1778 F. Fernandes et al. / Biochimi
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apparently the most significant as
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110
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Introduction Quinolones are broad-s
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[9-12]. Having this into considerat
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any case, very similar, probably wi
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placement of the protein around the
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⎛ II t ⎛ R ⎞ 0 ρ () t = exp
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APPENDIX - Derivation of the FRET r
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2 2w J ( t) = '2 R − R + w / 1
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[14] L. Plançon, M. Chami, L. Lete
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acceptors) (Eqs. 4-6) (⋅-⋅-⋅)
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FIGURE 1A FIGURE 1B 130
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136
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dynamin. Soon after, the same group
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140
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142
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Introduction Control of membrane re
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Steady-state fluorescence measureme
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Rho-DOPE (acceptor). The increase o
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where η is the viscosity of the me
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ound conformation of the BAR domain
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19. Fernandes, F., L. M. S. Loura,
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Figure Legends Fig.1: N-terminal am
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FIG. 1A FIG.1B 17
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FIG. 3A FIG. 3B 19
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FIG.5A 21
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FIG 6. 23
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FIG. 8 A B 25
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The signalling functions of PI(4,5)
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172
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174
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zoxadiazol (NBD)-PC were obtained f
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Fig. 3. Fluorescence decays of diph
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CONCLUSIONS VII CONCLUSIONS Chapter
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CONCLUSIONS constants recovered by
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CONCLUSIONS Chapter IV ‐ Binding
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CONCLUSIONS Chapter VI - Clustering
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FINAL CONSIDERATIONS AND PROSPECTS
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BIBLIOGRAPHY IX BIBLIOGRAPHY Albert
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BIBLIOGRAPHY Phosphatidylinositol 4
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BIBLIOGRAPHY Glaubitz, C., Grobner,
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BIBLIOGRAPHY Koehorst, R. B. M., Sp
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BIBLIOGRAPHY Mishra, V. K., Palguna
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BIBLIOGRAPHY Pluschke, G., Hirota,
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BIBLIOGRAPHY Sperotto, M. M., and M
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BIBLIOGRAPHY Williamson, I. M., Alv
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