Enolization and enolate anion biochemistry

Let us now look at an example of how nature exploits the equivalent of enol and enolate anion chemistry. Enolization provides another application 

The enzymic processes appear exactly equivalent, except that protons are removed and supplied through the involvement of peptide side-chains. It is unlikely that a distinct enolate anion is formed instead, we should consider the process as concerted with a smooth flow of electrons. Thus, as a basic group removes a proton from one part of the molecule, an acidic group supplies a proton at another. 

The example of triose phosphate isomerase in Box 13.6 provides us with an easily understood analogy. 

Triose phosphate isomerase enotization via acid-base catalysis 

Triose phosphate isomerase is one of the enzymes of glycolysis (see Section 15.2) and is responsible for converting dihydroxyacetone phosphate into glyceraldehyde 3-phosphate by a two-stage enolization process. An intermediate enediol is involved - this common enol can revert to a keto form in two ways, thus providing the means of isomerization. 

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