Reaction 2: Dehydration of an alcohol
Two steps (Rx. 2 and 3) are required to isomerize the position
of the -OH group on citric acid. This first step is a dehydration
of an alcohol to make an alkene. The cis-aconitic acid remains
bound to the enzyme aconitase in readiness for the next step.
This reaction is catalyzed by aconitase.