| Abstract: | A critical reappraisal of the concept of intramolecularity is attempted, but particulary focussed on the effective molarity (EM) criterion and the relationship of intramolecularity to enzymic reactivity. The prevalent ambiguities in the EM concept are addressed and a revised definition (EMrev) is suggested. It is argued that there are fundamental limitations to the use of intramolecular reactions as enzyme models. Although the simplest mechanism for enzymic reactivity is based on transition state stabilisation, an alternative (although complex) possibility is based on the stabilisation of the enzyme. Possible mechanisms for the utilisation of the enzymic free energy for effecting catalysis are discussed. |
