Biomembrane models

Elbert R, Laschewsky A and Ringsdorf H 1985 Hydrophilic spacer groups in polymerizable lipids— formation of biomembrane models from bulk polymerized lipids J. Am. Ohem. Soc. 107 4134-41... 

An exhaustive review by H. Ringsdorf (M. Ahlers, 1990) on biomembrane models and a recent book by F. Voegtle (1991) on supramolccular chemistry are recommended for further studies in this area. 

Lipophilicity is intuitively felt to be a key parameter in predicting and interpreting permeability and thus the number of types of lipophilicity systems under study has grown enormously over the years to increase the chances of finding good mimics of biomembrane models. However, the relationship between lipophilicity descriptors and the membrane permeation process is not clear. Membrane permeation is due to two main components the partition rate constant between the lipid leaflet and the aqueous environment and the flip-flop rate constant between the two lipid leaflets in the bilayer [13]. Since the flip-flop is supposed to be rate limiting in the permeation process, permeation is determined by the partition coefficient between the lipid and the aqueous phase (which can easily be determined by log D) and the flip-flop rate constant, which may or may not depend on lipophilicity and if it does so depend, on which lipophilicity scale should it be based ... 

Ottova A, Tvarozek V, Racek J, Sabo J, Ziegler W, Hianik T, Tien HT (1997) Self-assembled BLMs biomembrane models and biosensor applications. Supramol Sci 4 101-112... 

Thus far, it could be shown that stable liposomes can be prepared by polymerization of lipids. These vesicle systems, however, are still far away from being a real biomembrane model. As of now, they do not show any typical biological behavior such as surface recognition, enzymatic activities, variable lipid distribution, and the ability to undergo fusion. 

There are two ways different in principle, to approach the problem of creating a polymeric biomembrane model. One can start out from a completely synthetic system and increase the similarity to natural systems by introducing natural lipids and... 

Fig. 28. Schematic presentation of the build up of stable biomembrane models via partial polymerization of the membrane. Key I t>, natural or synthetic lipids Hi, polymerizable lipids >...

Sakai, N., Mareda, J., Matile, S., Rigid rod molecules in biomembrane models From hydrogen-bonded chains to synthetic... 

Lehmann T, Riihe J (1999) Polyethyloxazoline monolayers for polymer supported biomembrane models. Macromol Symp 142 1-12... 

Order and Mobility are two basic principles of mother nature. The two extremes are realized in the perfect order of crystals with their lack of mobility and in the high mobility of liquids and their lack of order. Both properties are combined in liquid crystalline phases based on the selforganization of formanisotropic molecules. Their importance became more and more visible during the last years in Material science they are a basis of new materials, in Life science they are important for many structure associated functions of biological systems. The main contribution of Polymer science to thermotropic and lyotropic liquid crystals as well as to biomembrane models consists in the fact that macromolecules can stabilize organized systems and at the same time retain mobility. The synthesis, structure, properties and phototunctionalization of polymeric amphiphiles in monolayers and multilayers will be discussed. 

Mouritsen OG, Andersen OS, eds. In Search of a New Biomembrane Model. 1998. Munksgaard, Copenhagen. 

R. A. Dluhy, S.M. Stephens, S. Widayatl and A.D. Williams, Vibrational Spectroscopy of Biophysical Monolayers. Applications of IR and Raman Spectroscopy to Biomembrane Model Systems at Interfaces, Spectrochim. Acta Part A51 (1995) 1413. (Review on biomembrane model systems studied by surface-sensitive vibrational spectroscopic methods. In particular the following methods are surveyed external reflectance IR spectroscopy, wave-guide Raman spectroscopy cmd SERS.)... 

W.W. (2003) Imaging coexisting fluid domains in biomembrane models coupling curvature and line tension. Nature, 425 (6960), 821-824. 

In this paper, we examine the Interactions of pyran copolymer with model biomembranes of two kinds 1) the human red blood cell membrane (or red cell "ghost") and 11) multilamellar suspensions (liposomes) of dlpalmltoylphosphatldylchollne (DFPC), a pure synthetic phospholipid. Each of these systems offers advantages In studies of polymer-cell surface Interaction The red cell membrane, idille complex. Is still the most readily Isolated and best understood of the membranes of nonnal human cells, and Its molecular architecture Is, In a general way at least, typical of such membranes. The pure phospholipids provide a much simpler biomembrane model, with the prospect of yielding more complete Interpretation of experimental observations. 

Nucleotides Peptides Biomembrane models, 350-351 Biotechnological procedures literature, 118 genetic engineering, 225-227, 350-351 in steroid synthesis, 278 2 -Bipyridines Cu(i) helicates from, 345-346 Birch reduction, 97-98... 

In this chapter, two subjects of our study were described. One was concerned with the catalysis by enzymes entrapped in water pools and photomerization at the level of a biomembrane model in vivo. Based on the study of the activity of yeast HK in the water pools, the activity of HK can be seen in noncharged polyoxyethylene mantles with relatively low micropolarity in which almost all the water molecules are bound up with EO chains. This suggests that yeast HK can work more actively in the vicinity of mitochondrial membranes in vivo. The photomerization of cysteine in the water pool with UV irradiation shows that cysteine is easily converted into cystine with lower Wg. This suggests that active oxygen is generated at the interface of the biomembrane rather than in bulk aqueous solution in vivo and SH groups of proteins in the cell membrane are oxidized similarly with UV irradiation. 

Antoloni, R., Gliozzi, A. and Gorio, A. (eds) (1982) Transport in Biomembranes Model Systems and Reconstitution, New York Raven Press. 

F. W. Wiegel, An Exactly Solvable Two-Dimensional Biomembrane Model, J. Stat. Phys. 13, 515-530 (1975). 

Micelles are recognized as simple biomembrane models. Biomembrane and micelles have amphiphilic properties and are anisotropic, providing hydrophobic and electrostatic interaction sites. MLC combines the unique characteristics of micelles and the capabilities of RPLC in quantitative retention-activity relationships studies. 

D. A. Cadenhead, Monomolecular films as biomembrane models in Structure and Properties of Cell Membranes. Methodology and Properties of Membranes Ed. G. Benga), CRC Press, Boca Raton, 1985, pp. 21—62, Vol. 3. 

The purpose of this paper is to establish the structural properties of totally artificial amphiphiles as biomembrane model and also, to investigate the water permeability of the composite membrane composed of polymer and artificial amphiphiles. 

---