Biological and model membranes

K. Kinosita, Jr., S. Kawato, and A. Ikegami, Dynamic structure of biological and model membranes Analysis by optical anisotropy decay measurement, Adv. Biophys. 17, 147-203 (1984). 

Measurement of the kinetic rates and surface diffusion of reversibly bound biomolecules at flattened biological and model membrane surfaces and at specifically derivatized glass surfaces (e.g., with immobilized enzymes). 

The structure of biological and model membranes is frequently viewed in the context of the fluid mosaic model [4], Since biological membranes are composed of a mixture of various lipids, proteins, and carbohydrates the supra-structure or lateral organization of the components is not necessarily random. In order to model biological membranes, lipid assemblies of increasing complexity were studied. Extensive investigation of multicomponent monolayers (at the air-water interface) as well as bilayers have been reported. 

We will discuss the chemical composition, size, and lifetime of domains in biological and model membranes. This area is currently under very active investigation, and we are likely to see further developments in the future. We will focus particularly on two types of membrane domains for which there is more evidence for their existence in biological membranes and more characterization of their properties. We can classify... 

Cheetham, J. J., Hpand, R. M., Andrews, M., and Flanagan, T. D. (1990). Cholesterol sulfate inhibits the fusion of Sendai virus to biological and model membranes. /. BieJ. Cfjcw. 265,12404-12409. 

An application of the optical microscopy to the detennination of the curvature elastic-modulus of biological and model membranes. Journal of Physics, 48 (5). 855-867. 

Petrov, A.G. and Bivas, 1. (1984) Elastic and flexoelectic aspects of out-of-plane fluctuations in biological and model membranes. Progress in Surface Science, 16 (4), 389-512. 

Bivas, P. Hanusse, P. Bothorel, J. Lalanne, and O. Aguerre-Chariol,/. Phys. (Paris), 48,855 (1987). An Application of the Optical Microscopy to the Determination of the Curvature Elastic Modulus of Biological and Model Membranes. 

The above properties and phenomena can be assessed with great sensitivity and precision by the measurement of rotational diffusion usually based upon the combined use of polarized excitation and deactivation processes. The faster motions alluded to above are particularly well adapted to the techniques of nuclear magnetic relaxation and fluorescence depolarization, the formalisms for which are extensively documented (references 2 and 3, respectively, and citations therein other chapters in this volume). Optical anisotropy decay measurements with longer time resolution have been very effective in studies of biological and model membrane systems (reviewed in 4-6). 

Kaprelyants, A., Suleimenov, M., Sorokina, A., Deborin, G., El-Registan, G., Stoyanovich, F., Lille, Yu., Ostrovsky, D. Structural-functional changes in bacterial and model membranes induced by phenolic lipids. Biological membranes, Vol.4, No.3, (March 1987), pp. 254-261, ISSN 0748-8653... 

A very brief description of biological membrane models, and model membranes, is given. Studies of lateral diffusion in model membranes (phospholipid bilayers) and biological membranes are described, emphasizing magnetic resonance methods. The relationship of the rates of lateral diffusion to lipid phase equilibria is discussed. Experiments are reported in which a membrane-dependent immunochemical reaction, complement fixation, is shown to depend on the rates of diffusion of membrane-bound molecules. It is pointed out that the lateral mobilities and distributions of membrane-bound molecules may be important for cell surface recognition. 

During recent decades, the use of artificial phospholipid membranes as a model for biological membranes has become the subject of intensive research. As discussed above, biological membranes are composed of complex mixtures of lipids, sterols, and proteins. Defined artificial membranes may therefore serve as simple models of membranes that have many striking similarities with biological membranes. A comparison of some important physicochemical properties of biological and artificial membranes is given in Table 1.8 [2]. 

Much of the interest in the interfaces between two immiscible electrolyte solutions (ITIES) derives from the fact that they can be regarded as models for biological and artificial membranes, which are currently actively studied by computer simulation methods (for an incomplete list, see Ref 270-275). 

Papahadjopoulos, D., Poste, G. and Vail, W.J. (1978) Studies on membrane fusion with natural and model membranes, in Methods in Membrane Biology (ed. E.D. Korn), Vol. 10, Plenum, New York, pp. 1-121. 

There is quite a large body of literature on films of biological substances and related model compounds, much of it made possible by the sophisticated microscopic techniques discussed in Section IV-3E. There is considerable interest in biomembranes and how they can be modeled by lipid monolayers [35]. In this section we briefly discuss lipid monolayers, lipolytic enzyme reactions, and model systems for studies of biological recognition. The related subjects of membranes and vesicles are covered in the following section. 

The first dynamical simulation of a protein based on a detailed atomic model was reported in 1977. Since then, the uses of various theoretical and computational approaches have contributed tremendously to our understanding of complex biomolecular systems such as proteins, nucleic acids, and bilayer membranes. By providing detailed information on biomolecular systems that is often experimentally inaccessible, computational approaches based on detailed atomic models can help in the current efforts to understand the relationship of the strucmre of biomolecules to their function. For that reason, they are now considered to be an integrated and essential component of research in modern biology, biochemistry, and biophysics. 

Seelig, J., and Seelig, A., 1981. Lipid conformadon in model membranes and biological membranes. Quarterly Review of Biophysics 13 19-61. 

Ion-selective bulk membranes are the electro-active component of ion-selective electrodes. They differ from biological membranes in many aspects, the most marked being their thickness which is normally more then 105 times greater, therefore electroneutrality exists in the interior. A further difference is given by the fact that ion-selective membranes are homogeneous and symmetric with respect to their functioning. However, because of certain similarities with biomembranes (e.g., ion-selectivity order, etc.) the more easily to handle ion-selective membranes were studied extensively also by many physiologists and biochemists as model membranes. For this reason research in the field of bio-membranes, and developments in the field of ion-selective electrodes have been of mutual benefit. 

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