Table Of ContentT H E F R O N T I E R S C O L L E C T I O N
Ole G. Mouritsen
Luis A. Bagatolli
L I F E –
A S A M AT T E R
OF FAT
Lipids in a Membrane
Biophysics Perspective
2 n d e d i t i o n
123
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THE FRONTIERS COLLECTION
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Ole G. Mouritsen Luis A. Bagatolli
(cid:129)
–
LIFE AS A MATTER
OF FAT
Lipids in a Membrane Biophysics Perspective
Second Edition
123
OleG.Mouritsen LuisA.Bagatolli
Department ofPhysics, Chemistry Department ofBiochemistry andMolecular
andPharmacy Biology
MEMPHYS-Center for Biomembrane MEMPHYS-Center for Biomembrane
Physics Physics
Odense Odense
Denmark Denmark
ISSN 1612-3018 ISSN 2197-6619 (electronic)
THEFRONTIERS COLLECTION
ISBN978-3-319-22613-2 ISBN978-3-319-22614-9 (eBook)
DOI 10.1007/978-3-319-22614-9
LibraryofCongressControlNumber:2015946589
SpringerChamHeidelbergNewYorkDordrechtLondon
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Preface
The first English edition of the present book was published in 2005 and although
stillinusearoundtheworldthetextcouldbemuchimprovedbyatimelyupdateon
several counts. Since 2005 the field of membrane biophysics has expanded tre-
mendouslyandmovedcenterstageinthestudyofbiological membranes,notleast
due to a tremendous development in the experimental techniques that can be
appliedtomembranes.Itwasdeemedusefultopreparearevisededitionofthebook
byincorporatingsomeoftheadvancesinthefieldoverthelastdecade.Inaddition,
thebooknowincludesmore tutorial material onthebiochemistryof lipids andthe
principles of lipid self-assembly.
The second edition greatly owes its materialization to the efforts of one of the
authors (LAB), who undertook a revision of the first edition (single-authored by
OGM)forpreparationofaSpanisheditionthatwaspublishedin2014.Thepresent
secondEnglisheditionistoagreatextentarevisedversionoftheSpanishedition.
The research work underlying the picture offats, lipids, and membranes advo-
cated in the present book derives from many different scientists and students in
severallaboratoriesacrosstheworld.Thespecificexamplesanddatapresentedare,
however,biasedtowardtheworkcarriedoutbytheauthorsandtheircollaborators.
Therefore,thebookshouldnotbeconsideredanauthoritativemonographbutmore
a personal perspective on a diverse and rapidly expanding field of science.
ThebookisprovidedwithaBibliographycontainingaselectedlistofreferences
to books, review papers, and research articles accounting for most of the factual
statements made in the book. These references to the literature have been selected
according to a minimal principle. The rule has been adopted that references are
mostly made to recent publications and not necessarily to the original work. From
thereferencesgiven,theinterestedreadershouldbeabletotrackdowntheoriginal
literature. The reader is furthermore referred to the list of specialized books and
review papers for a more comprehensive list of references. We apologize in
advance to those authors and colleagues who may feel that their original work
should have been referenced and discussed in more detail.
v
vi Preface
The authors have over the years benefited from stimulating interaction and
fruitful collaboration with a large number of colleagues and students, in particular
from the Center for Biomembrane Physics (MEMPHYS) at the University of
Southern Denmark.
The authors have drawn on the help from a number of colleagues and the
permission to use some of their graphic material for preparing many of the figures
of this book. A list of the sources for the figures is provided at the end.
Odense Ole G. Mouritsen
May 2015 Luis A. Bagatolli
Contents
Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Prologue: Lipidology—The Science of Lipids . . . . . . . . . . . . . . . . . xiii
Part I The Overlooked Molecules
1 Life from Molecules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 The Three Kingdoms of Life . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 The Molecules of Life. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3 A Brief Historical Overview of Membrane Theory . . . . . . . . . 6
1.4 Membranes in Cellular Systems . . . . . . . . . . . . . . . . . . . . . . 9
1.5 The Post-genomic Era. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.6 A Call for Physics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2 Head and Tail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.1 Fat Family: Fats and Fatty Acids . . . . . . . . . . . . . . . . . . . . . 19
2.2 The Polar Lipids—Both Head and Tail . . . . . . . . . . . . . . . . . 22
2.3 Cholesterol—A Lipid of Its Own . . . . . . . . . . . . . . . . . . . . . 28
2.4 Strange Lipids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.5 Lipid Composition of Membranes. . . . . . . . . . . . . . . . . . . . . 30
3 Oil and Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.1 Water—The Biological Solvent. . . . . . . . . . . . . . . . . . . . . . . 31
3.2 The Hydrophobic Effect. . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.3 Mediating Oil and Water. . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.4 Self-assembly and the Lipid Aggregate Family. . . . . . . . . . . . 35
3.5 Thermodynamics of Lipid Self-assembly . . . . . . . . . . . . . . . . 38
3.6 Plucking Lipids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
vii
viii Contents
4 Lipids Speak the Language of Curvature. . . . . . . . . . . . . . . . . . . 45
4.1 How Large Is a Lipid Molecule?. . . . . . . . . . . . . . . . . . . . . . 45
4.2 Lipid Molecules Have Shape . . . . . . . . . . . . . . . . . . . . . . . . 47
4.3 Lipid Structures with Curvature . . . . . . . . . . . . . . . . . . . . . . 50
4.4 Microorganisms’ Sense for Curvature . . . . . . . . . . . . . . . . . . 52
5 A Matter of Softness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.1 Soft Matter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.2 Soft Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.3 Forces Between Soft Interfaces. . . . . . . . . . . . . . . . . . . . . . . 60
5.4 Lipid Membranes are Really Soft . . . . . . . . . . . . . . . . . . . . . 61
6 Soft Shells Shape Up. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
6.1 Bending Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
6.2 Spontaneous Curvature . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
6.3 Shaping Membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
6.4 Red Blood Cells Shape Up . . . . . . . . . . . . . . . . . . . . . . . . . 72
7 Biological Membranes—Models and Fashion . . . . . . . . . . . . . . . . 75
7.1 What Is a Model?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
7.2 Brief History of Membrane Models. . . . . . . . . . . . . . . . . . . . 77
7.3 Do We Need a New Membrane Model? . . . . . . . . . . . . . . . . 79
7.4 Theoretical and Experimental Model Systems. . . . . . . . . . . . . 81
Part II Lipids Make Sense
8 Lipids in Bilayers—A Stress-Full and Busy Life. . . . . . . . . . . . . . 85
8.1 Trans-Bilayer Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
8.2 The Lateral Pressure Profile. . . . . . . . . . . . . . . . . . . . . . . . . 87
8.3 How Thick are Membranes?. . . . . . . . . . . . . . . . . . . . . . . . . 89
8.4 Lively Lipids on the Move. . . . . . . . . . . . . . . . . . . . . . . . . . 90
9 The More We Are Together . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
9.1 Phase Transitions Between Order and Disorder. . . . . . . . . . . . 95
9.2 Lipids Have Phase Transitions . . . . . . . . . . . . . . . . . . . . . . . 98
9.3 Mixing Different Lipids. . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
9.4 Cholesterol Brings Lipids to Order . . . . . . . . . . . . . . . . . . . . 106
10 Lipids in Flatland. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
10.1 Gases, Liquids, and Solids in Two Dimensions. . . . . . . . . . . . 111
10.2 Langmuir and Langmuir-Blodgett Films. . . . . . . . . . . . . . . . . 113
10.3 Pattern Formation in Lipid Monolayers . . . . . . . . . . . . . . . . . 116
10.4 Lipids Make the Lung Work . . . . . . . . . . . . . . . . . . . . . . . . 119
Contents ix
11 Social Lipids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
11.1 Lateral Membrane Structure. . . . . . . . . . . . . . . . . . . . . . . . . 125
11.2 Imaging Lipid Domains. . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
11.3 Lateral Membrane Heterogeneity and Domains. . . . . . . . . . . . 132
11.4 Membrane Domains Carry Function . . . . . . . . . . . . . . . . . . . 138
11.5 Active Membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
12 Lively Lipids Provide for Function . . . . . . . . . . . . . . . . . . . . . . . 143
12.1 Leaky and Thirsty Membranes . . . . . . . . . . . . . . . . . . . . . . . 143
12.2 Repelling Membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
12.3 Enzymes Can Sense Membrane Transitions . . . . . . . . . . . . . . 147
12.4 Lipid Thermometer in Lizards . . . . . . . . . . . . . . . . . . . . . . . 149
13 Proteins at Lipid Mattresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
13.1 Coming to Terms with Lipids. . . . . . . . . . . . . . . . . . . . . . . . 151
13.2 Anchoring at Membranes. . . . . . . . . . . . . . . . . . . . . . . . . . . 153
13.3 Spanning the Membrane . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Part III Lipids in Action
14 Cholesterol on the Scene. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
14.1 Molecule of the Century . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
14.2 Evolutionary Perfection of a Small Molecule . . . . . . . . . . . . . 164
14.3 Cholesterol Fit for Life . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
14.4 Cholesterol as a Killer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
15 Lipids in Charge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
15.1 Lipids and Proteins Match Up . . . . . . . . . . . . . . . . . . . . . . . 173
15.2 Stressing Proteins to Function. . . . . . . . . . . . . . . . . . . . . . . . 179
15.3 Lipids Opening Channels. . . . . . . . . . . . . . . . . . . . . . . . . . . 183
15.4 Lipids Mediate Fusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
16 Being Smart—A Fishy Matter of Fat. . . . . . . . . . . . . . . . . . . . . . 189
16.1 The Essential Fatty Acids. . . . . . . . . . . . . . . . . . . . . . . . . . . 189
16.2 Evolution of the Human Brain . . . . . . . . . . . . . . . . . . . . . . . 191
16.3 Lipids at the Border of Madness. . . . . . . . . . . . . . . . . . . . . . 193
17 Liquor and Drugs—As a Matter of Fat. . . . . . . . . . . . . . . . . . . . 195
17.1 Lipids Are Targets for Drugs . . . . . . . . . . . . . . . . . . . . . . . . 195
17.2 Alcohol and Anesthesia. . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
17.3 Poking Holes in Membranes. . . . . . . . . . . . . . . . . . . . . . . . . 198
17.4 Gramicidin—The Portable Hole . . . . . . . . . . . . . . . . . . . . . . 200
