Positively charged groups

To be contrasted with a negatively charged metal surrounded by positively charged groups. The idea of neutral ligands with donor lone pairs will be considered in due course. 

Figure6-10. Mode of binding of 2,3-bisphosphoglycerate to human deoxyhemoglobin. BPG interacts with three positively charged groups on each p chain.

The effects that proximal positively charged groups can have on the DEA process were the primary focus in Ref. [5]. Specifically, we considered the Coulomb stabilization that one or more nearby positive groups (e.g., simulating the protonated Lys sites in the molecule shown in Fig. 1) can have on the nascent a anion. As an example of the effects of Coulomb interactions, in Fig. 3 we show the MeS-SMe neutral and MeS-SMe a anion potentials as in Fig. 2 but calculated in the presence of two +1 charges each 30 or 10 A from the midpoint... 

Picric acid (trinitrophenol) and trinitroresorcinol, when added to fixative solutions, give greater fine structural preservation of cells (11,12). These compounds cause coagulation of proteins by forming salts with positively charged groups of proteins (11). The protein precipitates that form retain their antigenicity (3). Picric acid or trinitroresorcinol are most often added to formalde-... 

Membranes can also be made of charge-modified pofyvinyfidenedifluo-ride binding NAs through electrostatic interaction of the positively charged groups of the membrane polymer with the phosphate backbone of the NA. 

A spectrophotometric technique showed that the isomeric vinyl phenyl dimethyl arsines reacted at similar rates in carbon tetrachloride solution, as did the isomeric allylphenyl dimethyl arsines 8). The bromination of the methiodides of the allyl compounds was studied to see if the presence of the positively charged group affected the reactivity of the... 

In every case an olefin is one of the products of the primary cracking step. Now by considering each reaction in reverse, a common denominator for all the designated cracking systems can be found in the chemistry of olefins. The answer lies in the character of the olefinic double bond, which comprises the normal valence pair electrons, and in addition two extra or pi electrons, which endow the double bond with the ability to attract positively charged groups, especially protons. This ability is expressed quantitatively by the proton affinity, which is shown below for propylene and isobutylene ... 

Still another and promising approach to mimic reactions catalyzed by protein-bound flavoquinone is the use of micellar and macromolecular systems so.iss-is ) In such systems the micro-environment of the flavin can be varied while negatively or positively charged groups can be located in the vicinity of the flavin. Available results indicate that the reactivity of flavin towards various reagents is enhanced in such systems as compared to the free system. 

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