Proteins liquid crystal phases

This suggests that the ordered structure is present in the resin solution as a liquid crystal and is maintained into the cured state. The presence of a liquid-crystal phase in natural proteins and synthetic polypeptides is well documented. The liquid-crystal structure is the result of an unique conformation which allows a highly ordered hydrogen bonding system to develop. 

It fits nicely into the picture of dual structure-phase views of biomesogenic organizations that objects of rod-like appearance , for instance the little world of the tobacco mosaic virus (which - its overall design reduced to a simple rod-like entity - became the starting point of Onsager s theory [37]), as well as much simpler protein and nucleic acid helices are typical mesophase formers in the classical liquid-crystal phase... 

Just like the traditional and obviously difficult to overcome scattered views of proteins, nueleic acids, membranes and carbohydrates as kingdoms of their own in molecular biology [7 a, 8 c, 33 p, q], the experimental findings in these new fields of liquid-crystal research constitute at present still a dispersed mosaic of details rather than the needed adequately complex and integrative picture [7 a, 17,18], While liquid-crystal phase investigations remain preferably limited to helical aspects of only a few con-... 

Evidence for surfactant aggregation into bilayers in protein-surfactant films was obtained by observing gel-to-liquid crystal-phase transitions by differential scanning calorimetry (DSC). This phase transition is related to the onset of fluidity of the hydrocarbon tails for surfactants arranged in bilayers [5-7]. Phase transition temperatures (T ) of Mb-surfactant films [19,24,25] were observed for all the surfactants in Fig. 2. For a given surfactant, values of films were within several °C of values for the corresponding vesicle dispersions. These results indicate that all of the surfactants are arranged in bilayers in the films. The presence of the protein does not seem to influence Tc in any consistent manner. 

DDAB films are in a lamellar liquid crystal phase at 25 C. The fluidity of this phase facilitates movement of the protein during voltammetry. In thick films, normal pulse voltammetry (NPV) limiting currents, a direct measure of [11,17] gave small NPV limiting currents for Mb-DD AB films at temperatures below the gel-to-Iiquid crystal phase transition temperature (T. ), where they are... 

Similar results were obtained in reconstitution experiments with Upophilin and proteolipid apoprotein-lecithin systems, sarcoplasmic reticulum Ca +, Mg +-ATPase, rhodopsin, and glycophorin. In all these cases deuterium NMR revealed only one lipid population while the epr spectra (as far as available) showed two components. The results further show that proteins either disorder orhave little effect on hydrocarbon chain order in membranes above the gel-to-liquid crystal phase transition temperature, Tc, of the pure lipids. 

Applying MD to systems of biochemical interest, such as proteins or DNA in solution, one has to deal with several thousands of atoms. Models for systems with long spatial correlations, such as liquid crystals, micelles, or any system near a phase transition or critical point, also must involve a large number of atoms. Some of these systems, including synthetic polymers, obey certain scaling laws that allow the estimation of the behaviour of a large system by extrapolation. Unfortunately, proteins are very precise structures that evade such simplifications. So let us take 10,000 atoms as a reasonable size for a realistic complex system. 

S-layer proteins adsorb preferentially at lipid films in the liquid-expanded phase [138] Crystalization is observed only at the liquid-condensed phase [138]... 

It has been shown by FM that the phase state of the lipid exerted a marked influence on S-layer protein crystallization [138]. When the l,2-dimyristoyl-OT-glycero-3-phospho-ethanolamine (DMPE) surface monolayer was in the phase-separated state between hquid-expanded and ordered, liquid-condensed phase, the S-layer protein of B. coagulans E38/vl was preferentially adsorbed at the boundary line between the two coexisting phases. The adsorption was dominated by hydrophobic and van der Waals interactions. The two-dimensional crystallization proceeded predominately underneath the liquid-condensed phase. Crystal growth was much slower under the liquid-expanded monolayer, and the entire interface was overgrown only after prolonged protein incubation. 

The first account is on Phase Incremented Pulses in NMR with Applications by S. Zhang, this is followed by Advances in NMR Studies of Liquid Crystals by R. Y. Dong, H. C. Bertram and H. J. Anderson report on Applications of NMR in Meat Science , NMR Characterization of Mechanical Waves is covered by G. Madelin, N. Baril, J. D. de Certaines, J.-M. Francone and E. Thiaudiere, the next account is on Aspects of Coherence Transfer in High Molecular Weight Proteins by P. Permi, the final chapter is on Local Dynamics in Polypeptides studied by Solid State 2H NMR by T. Hiraoki, S. Kitazawa and A. Tsutsumi. 

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