Electrostatic contact

Weatherley (1998) has discussed all the relevant aspects of the separation of low molecular weight biologically produced molecules by solvent extraction. A high degree of selectivity can be realized by careful selection of the solvent. Problems associated with the rheology of the broth, the presence of surfactants and solid materials needs to be recognized. There is a scope to consider intensified electrostatic contact for broth dispersion and separation. Examples covered in this treatise include penicillin G and cA-dihydrodiols. 

In a real biological system, DNA is mostly surrounded by many proteins. Protein binding to DNA involves a number of hydrogen bonds and electrostatic contacts between two biopolymers, and induces not only structural deviation from the typical B-form structure, but also electronic perturbation of the -stacked array of base pairs. We tackled the electronic effects of protein binding on the efficiency of hole transport by using a restriction en-... 

Increasing the solvation causes the C,—Li contact to be gradually given up whereas the electrostatic contact of the lithium to the a-carbon is maintained. However, the estimation of the solvation number in the solid state shows the presence of two THF molecules per lithium. This study suggests that specific solvation increases the ability of the sulfur group to localize the negative charge on the a-carbon atom (a-heteroatom stabilization). 

Fuoss adopted the concept of the electrostatic contact ion-pair [60] and considered the anion as a point charge that may also penetrate the cation-conducting sphere of radius a. The final expression for the ion-pairing equilibrium constant,... 

Figure 10.21 Electrostatic contact and hydrophobic binding of a molecular model with anionic and hydrophobic properties.

The vanadate centre in the haloperoxidases not only is covalently bonded to a histidine, but also is in electrostatic contact with arginine and, through a hydrogen bonding network, with lysine, histidine, serine and water (Figure 4.16). The ionic interaction... 

The ct-3 helix of cl is called the recognition helix, because when cl is bound to DNA, its position deep within the major groove allows it to contact specific DNA bases and hence to determine sequence specificity of binding. The cn-2 helix is in contact primarily with DNA phosphates. These electrostatic contacts strengthen binding but do not contribute to specificity. 

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