Electrostatic changing

J. Weiss, Proc. Roy. Soc. London A222 128 (1954). First electron transfer theory in terms of electrostatic changes, including energy of reorganization, opt and stat, adiabatic and nonadiabatic theory, and much else. 

The early part of the M phase is dominated by reactions in the extracellular region in response to the electrostatic changes at the Schiff base. The titration behavior of Asp-85 revealed that there is coupling between the protonation state of this aspartate and another protonatable group (Govindjee etal., 1996). All five M structures show that the means of this... 

Brown, L., Kamikubo, H., Zimanyi, L., Kataoka, M., Tokunaga, F., Verdegem, P., Lugten-burg, J., and Lanyi, J. K. (1997). A local electrostatic change is the cause of the large-scale protein conformation shift in bacteriorhodopsin. Proc. Natl. Acad. Sci. USA 94, 5040-5044. 

The structures of HNLs from several plant species have been elucidated, giving insight into the respective mechanisms of cyanohydrin formation. The origin of these enzymes and thus the mechanisms of their action differ widely. The (S)-HNL from Hevea brasiliensis has a catalytic triad in its active center, which effects deprotonation of HCN and site-selective attack of CN to the substrate, which is fixed in the active site. In contrast, the HNL from Prunus amygdalus is a flavo-en-zyme. However, the role of the flavin group in the catalytic cycle is unclear. The present hypothesis states that the enzyme seems to act via electrostatic change of... 

Fig. 8A-C. Molecular switches based on the binding ability of crown ethers. A A photo-switchable binding event based on conformational change upon azobenzene isomerization. B A photoswitchable binding event based on both conformational and electrostatic changes. C A redox-switchable calix[4]arene-crown ether...

The electrostatic nature of the binding between the DNA polyanion and the various cations is explained by the existence of a diffuse electrostatic change-effect, which induces the formation of the DNA-M " " adducts. 

The role of metals in associative mechanisms can be multifaceted. If the phosphate and nucleophile are anionic then the attack can be promoted by coordination of the cationic metal ion either to the nucleophile or to the phosphate ester. The resulting complex ha a lower electrostatic barrier to reaction. Beyond the electrostatic change, coordination of the metal to the phosphate anion should make the central phosphorus more electrophilic and lower the kinetic barrier for nucleophilic addition. 

Changes in chromatin structure (and resulting changes in transcriptional activity) as a result of histone modifications are thought to occur in one of two ways modifications may result in steric or electrostatic changes to histone tails which change the nature of the histones interactions with DNA, or, alternatively, modifications may recruit modification-specific binding domains... 

For some purposes, good electrical conductivity or resistance to development of electrostatic change is needed in a composite structure. A range of conductive fibres is available for incorporation to satisfy these requirements. These include fine metal fibres, already discussed, but also glass, carbon and other fibres coated or impregnated with conductive material, usually a metal such as aluminium. 

A consequence is that such tautomerizations can not only take place in the liquids but often also in the solid state. The reaction barriers depend strongly on the heavy atom distances 2 and the energy needed for their compression. The occurrence of major electrostatic changes in the transition or intermediate states will only lead to a barrier increase which might, however, be substantial. In the following examples, different reaction types are discussed, which have been studied using dynamic liquid and solid state NMR. 

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