Conservation of effective charge

Assuming that the changes in effective charge shown in Scheme 3 are conserve(C the p values relating rate and equilibria are given in Equation (1). The principle of conservation of effective charge enables the calculation of charges for reactions not easily accessible to direct measurement. 

Assuming the conservation of effective charge, construct a full effective charge map for an identity reaction of phenolate ions with... 

The Bronsted in the range of > pA a (7-10) is 0.95. The overall Peq for the reaction is 1.42. Draw an effective charge map for the reaction and apply the conservation of effective charge to show that the Peq for the second step (Keq(2)) is too large to support the stepwise process shown. 

Now we can ask what is likely to happen to the three-dimensional structure of a protein if we make a conservative replacement of one amino acid for another in the primary structnre. A conservative replacement involves, for example, substitution of one nonpolar amino acid for another, or replacement of one charged amino acid for another. Intnitively, one would expect that conservative replacements would have rather little effect on three-dimensional protein structure. If an isoleucine is replaced by a valine or leucine, the structnral modification is modest. The side chains of all of these amino acids are hydrophobic and will be content to sit in the molecnlar interior. This expectation is borne out in practice. We have noted earlier that there are many different molecnles of cytochrome c in nature, all of which serve the same basic function and all of which have similar three-dimensional structnres. We have also noted the species specificity of insulins among mammalian species. Here too we find a number of conservative changes in the primary structure of the hormone. Although there are exceptions, as a general rule conservative changes in the primary structnre of proteins are consistent with maintenance of the three-dimensional structures of proteins and the associated biological functions. 

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