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On the Morphology and Dynamics of Purple Membranes at the Solid-Liquid Junction [Elektronische Ressource] / Roelf-Peter Baumann. Betreuer: Norbert Hampp

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79 Pages
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OntheMorphologyandDynamicsofPurpleMembranesattheSolid-LiquidJunctionkumulativeDissertationzur Erlangung des Doktorgrades der Naturwissenschaften(Dr. rer. nat.)demFachbereich Chemieder Philipps-Universität Marburgvorgelegt vonRoelf-PeterBaumannausLübeckMarburg an der Lahn, 2011Abgabedatum: 03.08.2011Erstgutachter: Prof. Dr. Norbert HamppZweitgutachter: Prof. Dr. Gregor WitteWoroheKräftesinnloswalten,dakannsichkeinGebildgestalten.FRIEDRICH VON SCHILLER (1759-1805),Lied von der GlockeContents1 Introduction 12 PurpleMembranefromHalobacteriumSalinarum 43 AtomicForceMicroscopy 63.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63.2 Tapping Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73.3 Single Molecule Force Spectroscopy . . . . . . . . . . . . . . . . . . . . 83.4 Electrostatic Force Microscopy . . . . . . . . . . . . . . . . . . . . . . . 94 CumulativePartOfDissertation 11A4.1 Dynamics of Bacteriorhodopsin . . . . . . . . . . . . . . . . . . . . . . 12B4.2 Crystallinity of Purple Membranes . . . . . . . . . . . . . . . . . . . . 16C,D4.3 Bending of Purple . . . . . . . . . . . . . . . . . . . . . 185 ConclusionAndOutlook 246 Zusammenfassung 267 Acknowledgements 298 Bibliography 309 Publications 35A Dynamics of Bacteriorhodopsin in Solid-Supported Purple MembranesStudied with Tapping-Mode Atomic Force Microscopy . . . . . . . . .

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Published 01 January 2011
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On the Morphology and Dynamics of Purple Membranes at the Solid-Liquid Junction
kumulative Dissertation
zur Erlangung des Doktorgrades der Naturwissenschaften (Dr. rer. nat.)
dem Fachbereich Chemie der Philipps-Universität Marburg vorgelegt von
Roelf-Peter Baumann
aus Lübeck
Marburg an der Lahn, 2011
Abgabedatum: Erstgutachter: Zweitgutachter:
03.08.2011 Prof. Dr. Norbert Hampp Prof. Dr. Gregor Witte
Wo rohe da kann
Kräfte sinnlos walten, sich kein Gebild gestalten.
FRIEDRICH VONSLLERCHI(1759-1805), Lied von der Glocke
Contents 1 Introduction 1 2 Purple Membrane fromHalobacterium Salinarum4 3 Atomic Force Microscopy 6 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.2 Tapping Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.3 Single Molecule Force Spectroscopy . . . . . . . . . . . . . . . . . . . . 8 3.4 Electrostatic Force Microscopy . . . . . . . . . . . . . . . . . . . . . . . 9 4 Cumulative Part Of Dissertation 11 4.1 Dynamics of BacteriorhodopsinA 12. . . . . . . . . . . . . . . . . . . . . . 4.2 Crystallinity of Purple MembranesB. . . . . . . . . . . . . . . . . . . . 16 4.3 Bending of Purple MembranesC,D. . . . . . . . . . . . . . . . . . . . . 18 5 Conclusion And Outlook 24 6 Zusammenfassung 26 7 Acknowledgements 29 8 Bibliography 30 9 Publications 35 A Dynamics of Bacteriorhodopsin in Solid-Supported Purple Membranes Studied with Tapping-Mode Atomic Force Microscopy . . . . . . . . . 37 B Crystallinity of Purple Membranes Comprising the Chloride-Pumping Bacteriorhodopsin Variant D85T and its Modulation by pH and Salinity 45 C Bending of purple membranes in dependence on the pH analyzed by AFM and single molecule force spectroscopy . . . . . . . . . . . . . . . 51 D pH-dependent Bending In and Out of Purple Membranes Comprising BR-D85T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 E Photochemistry of Coumarin-Functionalized SiO2 68Nanoparticles . . . . i
1 Introduction
On one side there is the ongoing trend to reduce the dimensionality of materials in the context of nanotechnology, driven by the keen aspiration to gain access to novel and unique properties as well as advanced performance characteristics that emerge in the transition to the nanoworld. The key aspect of nanotechnology is, that upon a decrease in size to the nanoscale, certain properties of matter become size-dependent which results in materials that exhibit quantum effects and are qualitatively different from their bulk counterparts. Size-dependent properties include but are not limited to: optical and magnetic properties, capillary forces, melting points, conductivity, ion-ization potential and electron affinity, reactivity, surface and interfacial energy etc. On the other side is the thriving pursuit to understand biological processes and systems, living organisms and derivatives thereof, in order to utilize them for technological applications in the applied part of biology commonly referred to as biotechnology. At the interface resides nanobiotechnology, one, if not the main emerging field of re-search in science and engineering of this century. Merging the fields of nano- and biotechnology, nanobiotechnology deals with the investigation and utilization of the newly conceived nanobiomaterials, as well as the construction of novel functional-ized nano-bio-hybrid-systems. Among many others, essential parts of nanobiotech-nology employ solid-supported architectures such as membrane assemblies. Taking the multidisciplinary nature of nanobiotechnology into account, the study of such nanobiointerfaces is more than just a study of how nanomaterials interact with bio-logical systems, but on an advanced level, it also elucidates the interfacial inter-actions between life sciences and nanoelectronics. By combining biomaterials like DNA, proteins, biomembranes or entire cells with electronic systems new exciting devices, sensors, and systems may be formed.1–4The nanobio interface characterized by its morphology and dynamics and governed by both extrinsic and intrinsic factors comprises the dynamic interactions between nanomaterial surfaces, such as carbon nanotubes, graphene, nanoparticles and biological components like DNA, proteins, biomembranes and even cells. This interplay at the solid-liquid junction between morphology and dynamics, both extrinsically and intrinsically influenced as illus-
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Chapter 1. Introduction
trated based on figure 1.1 is to be studied by the paradigm of membrane proteins and biomembranes namely bacteriorhodopsin (BR) and purple membrane (PM).
Figure 1.1:characterizing biomembrane systems at the solid-liquid junctionInterplay
Key questions of this investigation are:
• Immobilization of membrane proteins on surfaces remains a challenge in nano-biotechnology because proper form and function is only retained in a near-native lipid environment. What does the nanobio interface in terms of morphol-ogy and dynamics of the extremely robust purple membrane under the extrinsic constraints of the solid-liquid junction look like?
• Beyond their importance for many physiological processes, dynamical transi-tions in biological membranes also bare implications for nanobiotechnology applications. Do solid-supported purple membranes exhibit such dynamics? What extrinsic and intrinsic factors constitute possible dynamic interactions and or changes?
• In their native host both sides of purple membranes are in touch with an aque-ous environment. Embedded bacteriorhodopsins therein are thus able to per-form large-scale conformational changes over the course of the photocycle with-
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Chapter 1. Introduction
out restriction by a solid support. In contrast to the native cell a solid-support represents a breaking of symmetry in terms of bending and is thus expected to have a profound influence on purple membrane form and function. To what ex-tend is transient or permanent bending of purple membrane influenced by the extrinsic constraints imposed by a solid-support and what implications arise from this confinement for technical applications? On a more fundamental level the question arises if membrane curvature is coupled intrinsically to bacteri-orhodopsin or governed extrinsically by the geometric constraints of theHalobac-terium salinarumcell or in this case the substrate surface?
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