Physics Of Biological Membranes

This book mainly focuses on key aspects of biomembranes that have emerged over the past 15 years. It covers static and dynamic descriptions, as well as modeling for membrane organization and shape at the local and global (at the cell level) scale. It also discusses several new developments in non-equilibrium aspects that have not yet been covered elsewhere. Biological membranes are the seat of interactions between cells and the rest of the world, and internally, they are at the core of complex dynamic reorganizations and chemical reactions. Despite the long tradition of membrane research in biophysics, the physics of cell membranes as well as of biomimetic or synthetic membranes is a rapidly developing field. Though successful books have already been published on this topic over the past decades, none include the most recent advances. Additionally, in this domain, the traditional distinction between biological and physical approaches tends to blur. This book gathers the most recent advances in this area, and will benefit biologists and physicists alike.

Physics, mathematics and chemistry all play a vital role in understanding the true nature and functioning of biological membranes, key elements of living processes. Besides simple spectroscopic observations and electrical measurements of membranes we address in this book the phenomena of coexistence and independent existence of different membrane components using various theoretical approaches. This treatment will be helpful for readers who want to understand biological processes by applying both simple observations and fundamental scientific analysis. It provides a deep understanding of the causes and effects of processes inside membranes, and will thus eventually open new doors for high-level pharmaceutical approaches towards fighting membrane- and cell-related diseases.

This book highlights recent advances in and diverse techniques for exploring the plasma membrane’s structure and function. It starts with two chapters reviewing the history of membrane research and listing recent advances regarding membrane structure, such as the semi-mosaic model for red blood cell membranes and the protein layer-lipid-protein island model for nucleated tissue cell membranes. It subsequently focuses on the localization and interactions of membrane components, dynamic processes of membrane transport and transmembrane signal transduction. Classic and cutting-edge techniques (e.g. high-resolution atomic force microscopy and super-resolution fluorescence microscopy) used in biophysics and chemistry are presented in a very comprehensive manner, making them useful and accessible to both researchers in the field and novices studying cell membranes. This book provides readers a deeper understanding of the plasma membrane’s organization at the single molecule level and opens a new way to reveal the relationship between the membrane’s structure and functions, making it essential reading for researchers in various fields.

An overview of recent experimental and theoretical developments in the field of the physics of membranes, including new insights from the past decade. The author uses classical thermal physics and physical chemistry to explain our current understanding of the membrane. He looks at domain and 'raft' formation, and discusses it in the context of thermal fluctuations that express themselves in heat capacity and elastic constants. Further topics are lipid-protein interactions, protein binding, and the effect of sterols and anesthetics. Many seemingly unrelated properties of membranes are shown to be intimately intertwined, leading for instance to a coupling between membrane state, domain formation and vesicular shape. This also applies to non-equilibrium phenomena like the propagation of density pulses during nerve activity. Also included is a discussion of the application of computer simulations on membranes. For both students and researchers of biophysics, biochemistry, physical chemistry, and soft matter physics.

This volume focuses on the modulation of biological membranes by specific biophysical properties. The readers are introduced to emerging biophysical approaches that mimick specific states (like membrane lipid asymmetry, membrane curvature, lipid flip-flop, lipid phase separation) that are relevant to the functioning of biological membranes. The first chapter describes innovative methods to mimic the prevailing asymmetry in biological membranes by forming asymmetrical membranes made of monolayers with different compositions. One of the chapters illustrates how physical parameters, like curvature and elasticity, can affect and modulate the interactions between lipids and proteins. This volume also describes the sensitivity of certain ion channels to mechanical forces and it presents an analysis of how cell shape is determined by both the cytoskeleton and the lipid domains in the membrane. The last chapter provides evidence that liposomes can be used as a minimal cellular model to reconstitute processes related to the origin of life. Each topic covered in this volume is presented by leading experts in the field who are able to present clear, authoritative and up-to-date reviews. The novelty of the methods proposed and their potential for a deeper molecular description of membrane functioning are particularly relevant experts in the areas of biochemistry, biophysics and cell biology, while also presenting clear and thorough introductions, making the material suitable for students in these fields as well.

The first volume of the Handbook deals with the amazing world of biomembranes and lipid bilayers. Part A describes all aspects related to the morphology of these membranes, beginning with the complex architecture of biomembranes, continues with a description of the bizarre morphology of lipid bilayers and concludes with technological applications of these membranes. The first two chapters deal with biomembranes, providing an introduction to the membranes of eucaryotes and a description of the evolution of membranes. The following chapters are concerned with different aspects of lipids including the physical properties of model membranes composed of lipid-protein mixtures, lateralphase separation of lipids and proteins and measurement of lipid-protein bilayer diffusion. Other chapters deal with the flexibility of fluid bilayers, the closure of bilayers into vesicles which attain a large variety of different shapes, and applications of lipid vesicles and liposomes. Part B covers membrane adhesion, membrane fusion and the interaction of biomembranes withpolymer networks such as the cytoskeleton. The first two chapters of this part discuss the generic interactions of membranes from the conceptual point of view. The following two chapters summarize the experimental work on two different bilayer systems. The next chapter deals with the process ofcontact formation, focal bounding and macroscopic contacts between cells. The cytoskeleton within eucaryotic cells consists of a network of relatively stiff filaments of which three different types of filaments have been identified. As explained in the next chapter much has been recently learned aboutthe interaction of these filaments with the cell membrane. The final two chapters deal with membrane fusion.

Biophysics represents perhaps one of the best examples of interdisciplinary research areas, where concepts and methods from disciplines such as physics, biology, b- chemistry, colloid chemistry, and physiology are integrated. It is by no means a new ?eld of study and has actually been around, initially as quantitative physiology and partly as colloid science, for over a hundred years. For a long time, biophysics has been taught and practiced as a research discipline mostly in medical schools and life sciences departments, and excellent biophysics textbooks have been published that are targeted at a biologically literate audience. With a few exceptions, it is only relatively recently that biophysics has started to be recognized as a physical science and integrated into physics departments’ curr- ula, sometimes under the new name of biological physics. In this period of cryst- lization and possible rede?nition of biophysics, there still exists some uncertainty as to what biophysics might actually represent. A particular tendency among phy- cists is to associate biophysics research with the development of powerful new te- niques that should eventually be used not by physicists to study physical processes in living matter, but by biologists in their biological investigations. There is value in that judgment, and excellent books have been published that introduce the int- ested reader to the use of physical principles for the development of new methods of investigation in life sciences.

This book aims to cover a broad range of topics in statistical physics, including statistical mechanics (equilibrium and non-equilibrium), soft matter and fluid physics, for applications to biological phenomena at both cellular and macromolecular levels. It is intended to be a graduate level textbook, but can also be addressed to the interested senior level undergraduate. The book is written also for those involved in research on biological systems or soft matter based on physics, particularly on statistical physics. Typical statistical physics courses cover ideal gases (classical and quantum) and interacting units of simple structures. In contrast, even simple biological fluids are solutions of macromolecules, the structures of which are very complex. The goal of this book to fill this wide gap by providing appropriate content as well as by explaining the theoretical method that typifies good modeling, namely, the method of coarse-grained descriptions that extract the most salient features emerging at mesoscopic scales. The major topics covered in this book include thermodynamics, equilibrium statistical mechanics, soft matter physics of polymers and membranes, non-equilibrium statistical physics covering stochastic processes, transport phenomena and hydrodynamics. Generic methods and theories are described with detailed derivations, followed by applications and examples in biology. The book aims to help the readers build, systematically and coherently through basic principles, their own understanding of nonspecific concepts and theoretical methods, which they may be able to apply to a broader class of biological problems.

An Introduction to Biological Membranes: From Bilayers to Rafts covers many aspects of membrane structure/function that bridges membrane biophysics and cell biology. Offering cohesive, foundational information, this publication is valuable for advanced undergraduate students, graduate students and membranologists who seek a broad overview of membrane science.