An enzyme catalyzes the reaction by changing the shapes of the molecules that stress the bonds holding together. Therefore the bond is weaker and will break down faster.
The activation energy of a reaction is lowered by enzyme.
Adenylate cyclase (AC)
It provides the energy necessary for the reaction to occur.
Yes. For example, FabZ catalyzes the dehydration of beta-hydroxyacyl-ACP to trans-2-acyl-ACP.