Electrostatic interactions hierarchy

The data presented in preceding sections demonstrate that there is a wide variety of distance and geometric dependences in the electrostatic interactions that occur in proteins. A distance dependence hierarchy of the potential energy of these electrostatic interactions is given below (the symbol is included to indicate dependence on spatial arrangement, and the symbol D is included to denote dependence on the relative orientation... 

The roles of the extensions in /3-crystallin subunit structure and function are matters of debate. It would seem, however, that they are involved in regulating interactions between the /3-crystallin subunits and their interactions with the Gland 7-crystallin subunits. As the concentration of proteins within the lens is very high, these interactions are of great importance in ensuring crystallin protein solubility and hence the maintenance of lens transparency. However, the specifics of which /3-crystallin subunits interact with each other, and the role of the extensions in this process, are not known, and extensive NMR analysis is required to elucidate the hierarchy of subunit interactions. Furthermore, the extensions in the /3-crystallin subunits undergo extensive post-translational modification, especially proteolysis, and these age-related changes alter the electrostatic interactions between the subunits. 

As one can easily note, a well-defined hierarchy of successive interaction energy approximations, varying from the most expensive MP2 method to the various electrostatic energy representation (the more simplified the theory, the less computationally demanding calculation), demonstrates the utility of this decomposition scheme (Figure 8-3) ... 

Interpreting bulk properties qualitatively on the basis of microscopic properties requires only consideration of the long-range attractive forces and short-range repulsive forces between molecules it is not necessary to take into account the details of molecular shapes. We have already shown one kind of potential that describes these intermolecular forces, the Lennard-Jones 6-12 potential used in Section 9.7 to obtain corrections to the ideal gas law. In Section 10.2, we discuss a variety of intermolecular forces, most of which are derived from electrostatic (Coulomb) interactions, but which are expressed as a hierarchy of approximations to exact electrostatic calculations for these complex systems. 

Spatial structure of protein molecules governs their essential properties, including surface activity. Native proteins (further, proteins) have the unique structure of molecules, ideal energetically balanced and created due to principle of structures hierarchy with optimal using of hydrogen bonds, dispersion, electrostatic, as well as hydrophobic interactions to stabilize the compact form of polypeptide chains. All structure elements of the protein molecule, including ordered ones (secondary structures), domains and globules, as well as protein... 

Components defined in such way naturally correspond to hierarchy of theoretical models of gradually decreasing complexity MP2, SCF, first order interaction energy E, electrostatic term E i, electrostatic multipole term be defined in the section 2.2). Such consistent division could be very useful in construction of simplified models based on more accurate theories. 

In summary, carboxylic acid prefers to bind to an N-heterocyclic moiety in preference to an amide moiety as Iraig as the base is sufficiently strong (e.g. pyridine, imidazole, and benzimidazole). However, if the basicity of the heterocycle is lowered enough, as was the case with 4-[(pyrazol-l-yl)methyl]-benzamide, the acid prefers to interact with the amide. We can therefore conclude that electrostatic charges provide a useful tool in establishing robust hydrogen-bond hierarchies that can be forged into effective supramolecular synthetic tools. 

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