The results from the previous six papers are collated so as to allow the construction of the complete free energy profile for the reaction catalyzed by proline racemase. This profile includes the step that involves the isomerization of the two forms of free enzyme, which can become rate limiting at very high substrate levels (in "oversaturation"). The mechanism of the reaction has been defined, the results being best accommodated by a route that involves a transition state or unstable intermediate in which the proline carbanion is flanked by the two catalytic thiols of the enzyme.