Question

What is the relationship between the rate of an enzyme reaction and the rate of the corresponding uncatalyzed reaction? Do enzymes enhance the rates of slow uncatalyzed reactions as much as they enhance the rates of fast uncatalyzed reactions?

Answer 1

Usually for a reaction to proceed and give out products they have come over the activation energy barrier. When the heat is not sufficient then the reaction will not be fast. At times the reaction won't proceed at all.
An enzyme is a catalyst.
Catalysts decrease the activation energy by decreasing the activation energy,

Answer 2

In a slow uncatalyzed reaction the activation barrier is really high therefore the reaction is slow.
In a fast uncatalysed reaction the activation energy is no longer a barrier. Therefore I think enzymes have a more impact on slow uncatalyzed reaction.