Effective Molarities for Intramolecular Reactions

The first step toward unravelling the mechanism of an enzyme-catalyzed reaction is to specify the mechanisms available for the reaction concerned. Many of these reactions are not observed when the relevant groups are allowed to come together in bimolecular processes in aqueous solution. For mechanistic work involving intermolecular reactions, it is necessary to use activated substrates. An attractive alternative is to study intramolecular reactions. These are generally faster than the corresponding intermolecular processes. Thus, groups like carboxyl and imidazole are involved at the active sites of many enzymes hydrolyzing aliphatic esters and amides. Therefore, mechanistic studies of intramolecular reactions play an important part in elucidating the chemistry of the groups involved in enzyme catalysis and in defining the mechanisms available for particular reactions.