Generic and Specific Roles of Saccharides at Cell and Bacteria Surfaces (eBook)

Generic and Specific Roles of Saccharides at Cell and Bacteria Surfaces 3
Supervisor’s Foreword 8
Acknowledgments 10
Contents 11
1 Introduction 14
References 18
2 Theoretical Background 21
2.1…Lipid Membranes 21
2.1.1 Physics of Lipids and Lipid Membranes 21
2.1.1.1 Membrane Formation by Lipid Self-Assembling 21
2.1.1.2 Phase Behavior of Lipid Membranes 23
2.1.2 Inter-Membrane Interactions 24
2.1.2.1 Hardcore Repulsion 25
2.1.2.2 Van der Waals Interaction 25
2.1.2.3 Hydration Repulsion 26
2.1.2.4 Undulation Repulsion 26
2.1.2.5 Electrostatic Interaction 27
2.1.2.6 The Disjoining Pressure 27
2.1.2.7 Force--Distance Relationships 28
2.1.3 Mechanics of Solid-Supported Membrane Multilayers 28
2.1.3.1 The Discrete Smectic Hamiltonian 28
2.1.3.2 Height--Height Correlation Functions 30
2.1.3.3 Membrane Displacement Correlation Functions 31
2.1.4 Membrane Models 31
2.1.4.1 Langmuir Lipid Monolayers 31
2.1.4.2 Solid-Supported Lipid Monolayers 33
2.1.4.3 Solid-Supported Lipid Bilayers 33
2.1.4.4 Solid-Supported Membrane Multilayers 34
2.2…Principles of X-Ray and Neutron Scattering 35
2.2.1 Basic Principles 35
2.2.1.1 X-Ray versus Neutrons 36
2.2.1.2 Scattering from Oriented Planar Samples 36
2.2.2 Specular Scattering 38
2.2.2.1 Specular Reflectivity from a Single Ideal Interface 38
2.2.2.2 Interfacial Roughness 40
2.2.2.3 Stratified Interfaces 41
2.2.2.4 Periodic Multilayers 42
2.2.3 Off-Specular (Diffuse) Scattering 42
2.2.3.1 Scattering from a Single, Topologically Rough Interface 43
2.2.3.2 Scattering from Stratified Interfaces with Correlated Topological Roughness 46
References 48
3 Materials and Methods 51
3.1…Materials 51
3.1.1 DPPC and Synthetic Glycolipids 51
3.1.1.1 DPPC 51
3.1.1.2 Gentiobiose lipid and Lac1 lipid 51
3.1.1.3 LeX lipid 52
3.1.2 Lipopolysaccharides 53
3.1.3 Chemicals and Buffers 54
3.1.3.1 Calcium-Free Buffers 55
3.1.3.2 Calcium-Loaded Buffers 55
3.2…Preparation Methods 55
3.2.1 Preparation of Solutions/Suspensions 55
3.2.1.1 DPPC and Synthetic Glycolipids 55
3.2.1.2 Lipid A and Rough Mutant LPS 55
3.2.1.3 PAOLPS 56
3.2.2 Preparation of Solid-Supported Membrane Multilayers 56
3.2.3 Preparation of Rough Mutant LPS Monolayers at the Air/Water Interface 57
3.2.4 Preparation of Solid-Supported PAOLPS Monolayers 57
3.3…Scattering Techniques 58
3.3.1 X-Ray Scattering 58
3.3.1.1 Specular X-Ray Reflectivity Experiments 58
3.3.1.2 GIXOS Experiments at the Air/Water Interface 58
3.3.1.3 X-Ray Fluorescence Experiments 59
3.3.2 Neutron Scattering 60
3.3.3 Sample Environments 62
3.3.3.1 Humidity Chamber for Neutron Scattering under Vapor Conditions 62
3.3.3.2 Liquid Cell for Neutron Scattering under Bulk Water Conditions 63
3.3.3.3 Liquid Cell for High-Energy X-Ray Reflectivity Measurements 64
References 64
4 Theoretical Modeling 67
4.1…Determination of Mechanical Properties of Interacting Membranes 67
4.1.1 Membrane Displacement Correlation Functions 67
4.1.2 Calculation of Specular and Off-Specular Scattering Signals 69
4.1.2.1 Beyond the Kinematic Approximation 74
4.1.2.2 Multiple Scattering 74
4.1.3 Summary of Sect. 4.1 76
4.2…Electrostatic Interactions between Charged Lipid Membranes 76
4.2.1 A Single Charged Surface in an Electrolyte 77
4.2.2 Two Charged Surfaces in an Electrolyte 78
4.2.3 The Weak-Overlap Approximation 80
4.2.4 Summary of Sect. 4.2 81
4.3…Interpretation of X-Ray Fluorescence Signals 81
4.3.1 Calculation of Illumination Profiles 82
4.3.2 Calculation of X-Ray Fluorescence Intensities 85
4.3.2.1 Absorption and Buffer-Normalized Fluorescence Intensities 87
4.3.3 Summary of Sect. 4.3 89
References 89
5 Inter-Membrane Interactions and Mechanical Properties of Membranes Composed of Synthetic Glycolipids 91
5.1…Influence of Molecular Structure: Cylindrical and Bent Saccharides 91
5.1.1 Phase Transitions of Glycolipid Membranes 92
5.1.2 Modulation of Inter-Membrane Interactions via Saccharide Conformation 94
5.1.3 Influence of Saccharide Conformation on Membrane Mechanics 95
5.1.3.1 Glycolipid Multilayers under Bulk Water 98
5.1.4 Summary of Sect. 5.1 99
5.2…Role of Specific Saccharide--Saccharide Interactions in Membrane--Membrane Contacts 100
5.2.1 Influence of LewisX Trisaccharides on Inter-Membrane Interactions 101
5.2.2 Specific Saccharide--Saccharide Interactions under Compressional or Tensile Stress 102
5.2.2.1 Interactions of the Matrix (DPPC) Membranes 102
5.2.2.2 Modification of Matrix Membrane Interactions with Calcium Ions 104
5.2.2.3 Cross-Linking the Membranes: Forces and Energies 106
5.2.3 Influence of LewisX on the Mechanics of Membrane Multilayers 107
5.2.4 Summary of Sect. 5.2 109
References 110
6 Structure and Mechanical Properties of Bacteria Surfaces 112
6.1…Influence of Lipopolysaccharide Structure and Divalent Cations on the Mechanics of LPS Multilayers 112
6.1.1 Influence on Inter-Membrane Interactions 113
6.1.2 Influence on Mechanical Properties 115
6.1.3 Summary of Sect. 6.1 118
6.2…Influence of Divalent Cations on the Conformation of Wild-Type Lipopolysaccharides 118
6.2.1 Effect of Divalent Cations: Electron Density Profile of LPS Monolayers 119
6.2.2 Modeling of LPS Saccharide Conformation by Coarse-Grained Monte Carlo Simulations 121
6.2.3 Summary of Sect. 6.2 123
6.3…Concentration Profiles of Monovalent and Divalent Cations at Bacteria Surfaces 124
6.3.1 Influence of Divalent Cations on Molecular Interactions in Langmuir Monolayers of LPS Re 124
6.3.2 Influence of Divalent Cations on Electron Density Profiles of LPS Re Monolayers 125
6.3.3 Ion Concentration Profiles at LPS Re Monolayers 127
6.3.4 Modeling of Ion Concentration Profiles at LPS Re Monolayers by Coarse-Grained Monte Carlo Simulations 131
6.3.5 Summary of Sect. 6.3 132
References 133
7 Conclusions 135
8 Outlook 137